Martensitic heat-resisting steel excellent in HAZ-softening resistance and process for producing the same

Abstract

A martensitic heat-resisting steel comprises, in terms of % by mass, 0.01 to 0.30% of C, 0.02 of 0.80% of Si, 0.20 to 1.00% of Mn, 5.00 to 18.00% of Cr, 0.005 to 1.00% of Mo, 0.20 to 3.50% of W, 0.02 to 1.00% of V, 0.01 to 0.50% of Nb, 0.01 to 0.25% of N, and at least one element selected from the group consisting of Ti, Zr, Ta and Hf in an amount of 0.005 to 2.0% for each of the elements, the volume of (Ti %+Zr %+Ta %+Hf %) in the metal component M of M.sub.23 C.sub.6 type carbides therein being from 5 to 65%. The heat-resisting steel is produced by a process comprising the steps ofadding Ti, Zr, Ta and Hf to a molten steel having chemical components as mentioned above, during the period from 10 minutes before completion of refining to completion of refining, casting said molten steel, working the resulting casting, solution treating said worked product, subjecting said worked product to temporary cooling stop at a temperature from 950.degree. to 1,000.degree. C. in the course of cooling said hot worked product, and holding said worked product at the temperature for 5 to 60 minutes. The heat-resisting steel is excellent in HAZ-softening resistance, and exhibits a high creep strength at high temperature of at least 550.degree. C.

Description

FIELD OF THE INVENTION

The present invention relates to a martensitic heat-resisting steel, and more in detail, to a martensitic heat-resisting steel excellent in HAZ-softening resistance and used in a high temperature and high pressure environment.

BACKGROUND OF THE INVENTION

Boilers of thermal power plants have been operated under conditions of markedly high temperature and high pressure in recent years. Part of them are planned to be operated at 566.degree. C. and 316 bar. It is estimated that some of them will operate at 649.degree. C. and 352 bar in the future. Accordingly, materials for such boilers will be used under extremely harsh conditions.

When the operation temperature exceeds 550.degree. C., materials used in the boilers will be changed, for example, from ferritic 21/4% Cr-1% Mo steel to an austenitic steel of high grade such as 18-8 stainless steel in view of oxidation resistance and high temperature strength. Thus, materials of very high grade and high cost are currently used.

Steel materials having an intermediate grade between 21/4% Cr-1% Mo steel and austenitic stainless steel have been searched for in the past several decades. Boiler tube steels containing an intermediate amount of Cr such as 9% Cr steel or 12% Cr steel have been developed on the basis of the demands described above. Some of the steels have attained a high temperature strength and a creep strength comparable to austenitic steels by precipitation strengthening or solid solution strengthening effected by adding a variety of alloying elements as base material components.

The creep strength of heat-resisting steels is governed by solid solution strengthening when the steels have been aged for a short period of time and by precipitation strengthening when they have been aged over a long period of time. This is because solid solution strengthening elements dissolved in the steels are precipitated at first as stable carbides such as M.sub.23 C.sub.6 by aging in many cases. However, when the steels are aged for a still longer period of time, the precipitates are coalescence coarsened, and as a result the creep strength is lowered. Many studies have, therefore, been performed on maintaining the solid solution strengthening elements in a solution state in the steels over a long period of time without precipitation in order to maintain the high creep strength of the heat-resisting steels.

For example, Japanese Patent Unexamined Publication (Kokai) Nos. 63-89644, 61-231139 and 62-297435 disclose ferritic heat-resisting steels which can achieve a creep strength far higher than a conventional Mo-added type ferritic heat-resisting steel by the use of W as a solid solution strengthening element. Many of these steels have a tempered martensite single phase as their structure, and are expected to become the next generation of materials for use in high temperature and high pressure environments due to their advantage as ferritic steels excellent in steam oxidation resistance and due to their high strength properties.

On the other hand, ferritic heat-resisting materials utilize the high strength of a martensite structure containing a large amount of dislocations or its tempered structure formed by the supercooling phenomenon of phase transformation from an austenite single phase region to (ferrite+carbide precipitate) the phase to be produced as a result of cooling during heat treatment. Accordingly, when the structure is subjected to a heat cycle of being reheated to the austenite single region, for example, when the structure is subjected to weld heat affection, the dislocations of high density are relieved again, and the strength is sometimes locally decreased in the weld HAZ (heat-affected zone).

Particularly among those portions which are reheated to a temperature of at least a ferrite-austenite transformation point, portions which has been heated to a temperature near the transformation point, for example, about from 900.degree. to 1,000.degree. C. in the case of 9% Cr steel, and recooled in a short period of time are subjected to martensite transformation while austenite grains do not grow sufficiently to become a fine grain structure. In addition, M.sub.23 C.sub.6 type carbides which are a principal factor in improving the materials strength by precipitation strengthening do not redissolve, and mechanisms for inducing a decrease in the high temperature strength such as alteration of the constituent components of the carbides, or carbide coarsening, may compositely act on the portion to locally become a softened zone. The softening zone-forming phenomenon is termed "HAZ-softening" for convenience.

DISCLOSURE OF THE INVENTION

The present inventors have carried out detailed studies on the softening zone, and found that the decrease in strength is caused mainly by a change of the constituent elements in M.sub.23 C.sub.6 type carbides. As the result of further investigation, they discovered that when high strength martensitic heat-resisting steel is being subjected to the weld heat affection, Mo or W particularly essential to solid solution strengthening thereof is dissolved in the constituent element M of M.sub.23 C.sub.6 in a large amount and precipitates at grain boundaries of the fine grain structure, and that as a result, a Mo- or W-depleted zone is formed near the austenite grain boundaries, resulting in a local decrease in the creep strength.

Accordingly, the decrease in the creep strength caused by weld heat affection is critically disadvantageous to heat-resisting materials. It is obvious that the prior art aiming at optimization of heat treatment and welding cannot solve the problems. In addition, it is evident that a countermeasure of completely austenitizing a welded portion again which had been recognized as the sole solution cannot be practiced when the process of construction and execution of works in power plant is taken into consideration. Accordingly, it is clear that manifestation of the "HAZ-softening" phenomenon is inevitable in a conventional heat-resisting martensitic or ferritic steel.

An object of the present invention is to overcome the disadvantage of the conventional steel, namely to avoid the formation of a local softening zone in a weld HAZ caused by alteration and coarsening of M.sub.23 C.sub.6 type carbides.

A further object of the present invention is to prevent Mo or W from being dissolved in M.sub.23 C.sub.6 in a large amount while the steel material is being subjected to weld heat affection.

To achieve the objects as mentioned above in the present invention, the composition and the precipitation size of M.sub.23 C.sub.6 type carbides in a weld HAZ are controlled.

As the result of intensively investigating the "HAZ-softening" phenomenon to achieve the objects as mentioned above, the present inventors have discovered that Ti, Zr, Ta and Hf each have an extremely strong affinity with C in the component system of the steel according to the present invention, that carbides of these elements become precipitation nuclei of M.sub.23 C.sub.6 carbides to be precipitated in the tempered martensite structure of the steel according to the present invention, and these elements dissolve in solid solution state at the same time in the metal component M in the carbides, that when the solid solution amount in the metal component M is within a specific range, the creep rupture strength of the weld HAZ falls down to only an extremely small value within the deviation of the creep rupture strength of the base material compared with the rupture strength thereof, and that as a result, the weld HAZ does not exhibit the "HAZ-softening" phenomenon any more.

The following process has been developed to realize the discovery.

First, since the precipitates of Ti, Zr, Ta and Hf are each required to become fine and appropriate, that is, since all of the precipitates must become carbides and carbonitrides, these elements are each added to the molten steel in a state of a low oxygen concentration immediately before completion of refining. Second, since these precipitates of Ti, etc. are required to become precipitation nuclei of M.sub.23 C.sub.6 to be precipitated within the tempered martensite structure and to be dissolved in solid solution state in the resultant carbides in suitable amounts, the steel slab is processed as follows: the steel slab having been subjected to a solid solution heat treatment is subjected to cooling stop at a temperature of 950.degree. to 1,000.degree. C. in the course of cooling; and the steel slab is held at the temperature for a predetermined period of time to sufficiently precipitate fine carbides of Ti, etc.

As described above, when a steel material having a martensite structure in which fine carbides of Ti, etc. are precipitated is tempered, M.sub.23 C.sub.6 type carbides are precipitated while the carbides of Ti, etc. are utilized as the precipitation nuclei. M.sub.23 C.sub.6 carbides and the fine carbides of Ti, Zr, Ta and Hf are mutually dissolved in each other, and finally M.sub.23 C.sub.6 type carbides in which Ti, Zr, Ta and Hf are solid solubled in the prescribed range in the metal component M, are formed in the tempered martensite structure. As a result, the creep rupture strength of the weld HAZ is significantly improved.

That is, the present invention provides a martensitic heat-resisting steel which comprises, in terms of % by mass, 0.01 to 0.30% of C, 0.02 to 0.80% of Si, 0.20 to 1.00% of Mn, 5.00 to 18.00% of Cr, 0.005 to 1.00% of Mo, 0.20 to 3.50% of W, 0.02 to 1.00% of V, 0.01 to 0.50% of Nb, 0.01 to 0.25% of N, up to 0.030% of P, up to 0.010% of S, up to 0.020% of O, at least one element selected from the group consisting of Ti, Zr, Ta and Hf in an amount of 0.005 to 2.0% for each of the elements, if necessary at least one element selected from the group consisting of Co, Ni and Cr in an amount of 0.2 to 5.0% for each of Co and Ni and 0.2 to 2.0% for Cu, and the balance Fe and unavoidable impurities, and which has in the tempered martensite structure precipitated M.sub.23 C.sub.6 type carbides, the value of (Ti %+Zr %+Ta %+Hf %) in the metal component M thereof being from 5 to 65%. The present invention provides a process for producing said heat-resisting steel comprising the steps of adding at least one element selected from the group consisting of Ti, Zr, Ta and Hf to a molten steel during the period from 10 minutes before completion of refining to completion thereof, subjecting the steel to temporary cooling stop at a temperature of 950.degree. to 1,000.degree. C. in the course of cooling the steel after solution heat treatment, holding the steel at that temperature for 5 to 60 minutes, and tempering it.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a butt groove shape of a welded joint.

FIG. 2 is a view showing a procedure for sampling test pieces for analyzing precipitates in a weld HAZ.

FIG. 3 is a diagram showing the relationship between the addition time of Ti, Zr, Ta and Hf, and the form and the average particle size of precipitates of Ti, Zr, Ta and Hf in the steel.

FIG. 4 shows graphs each showing the relationship between a temporary cooling stop temperature after solution treatment and a holding time thereat, and the particle size of the precipitated carbides.

FIG. 5 is a diagram showing the relationship between a temporary cooling stop temperature after solution treatment, and the form and the structure of the precipitates in a weld HAZ.

FIG. 6 is a graph showing the relationship between a difference (D-CRS) between the creep rupture strength at 600.degree. C. for 100,000 hours estimated by linear extrapolation of a base steel and that of a weld HAZ, and the value of M % (Ti %+Zr %+Ta %+Hf %) in M of M.sub.23 C.sub.6 type carbides in the weld HAZ.

FIG. 7 is a graph showing the relationship between the creep rupture strength at 600.degree. C. for 100,000 hours estimated by linear extrapolation of a base steel and the value of Ti %+Zr %+Ta %+Hf % in the base steel.

FIG. 8 is a graph showing the relationship between the value of M % (Ti %+Zr %+Ta %+Hf %) in M of M.sub.23 C.sub.6 type carbides in the weld HAZ and the toughness thereof.

FIG. 9(a) and FIG. 9(b) are views showing a procedure for sampling a creep rupture strength test piece from a steel tube and a procedure therefor from a plate or sheet, respectively.

FIG. 10(a) and FIG. 10(b) are views showing a procedure for sampling a creep rupture test piece from a weld zone of a steel tube and a procedure therefor from a weld zone of a plate or sheet, respectively.

FIG. 11(a) and FIG. 11(b) are views showing a procedure for sampling a Charpy impact test piece from a weld zone of a steel tube and a procedure therefor from a weld zone of a plate or sheet, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be explained.

First, the reasons for restricting the contents of components in the molten steel in the present invention as mentioned above are described below. A content expressed in terms of % signifies a content in terms of % by mass.

Though C is necessary for maintaining the strength of the steel, C in a content of less than 0.01% is insufficient for ensuring the strength of the steel. When the content of C exceeds 0.30%, the weld HAZ is markedly hardened, and as a result cold cracking is formed at the time of welding. Accordingly, the content range of C is defined to be from 0.01 to 0.30%.

Si is important in ensuring the oxidation resistance of the steel, and it is also a necessary element as a deoxidizing agent. Si in a content of less than 0.02% is insufficient, and Si in a content exceeding 0.80% lowers the creep strength of the steel. Accordingly, the content range of Si is defined to be from 0.02 to 0.80%.

Mn is a component necessary not only for deoxidization but also for maintaining the strength of the steel. Addition of Mn in a content of at least 0.20% is necessary for obtaining a sufficient effect. Mn in a content exceeding 1.00% may sometimes lower the creep strength of the steel. Accordingly, the content range of Mn is defined to be from 0.20 to 1.00%.

Cr is an element essential to the oxidation resistance of the steel. Cr combines with C at the same time in forms of Cr.sub.23 C.sub.6 .multidot.Cr.sub.7 C.sub.3, etc. to form fine precipitates in the base steel matrix, and thus contributes to an increase in the creep strength of the steel. From the standpoint of oxidation resistance, the lower limit of the Cr content is defined to be 5.0%. The upper limit thereof is defined to be 18.0% from the standpoint of ensuring a high temperature strength of the steel and in view of the limit for achieving a martensite single phase.

W is an element significantly enhancing the creep strength of the steel through solution hardening. W particularly increases the long term creep strength at high temperatures of at least 550.degree. C. When K is added in a content exceeding 3.5%, it precipitates mainly at grain boundaries as intermetallic compounds in a large amount. As a result, the toughness and the creep strength of the base steel are markedly lowered. The upper limit of the W content is, therefore, defined to be 3.5%. Moreover, W in a content of less than 0.20% is insufficient for achieving the effect of solid solution strengthening. Accordingly, the lower limit of the W content is defined to be 0.20%.

Mo also enhances the high temperature strength of the steel through solid solution strengthening. Mo in a content of less than 0.005% is insufficient for achieving the effect. Since Mo.sub.2 C type carbide is precipitated in a large amount or Mo.sub.2 Fe type intermetallic compound is precipitated when the content of Mo exceeds 1.00%, simultaneous addition of Mo and W may considerably lower the toughness of the base steel. Accordingly, the upper limit of the Mo content is defined to be 1.00%.

V is an element which significantly enhances the high temperature creep rupture strength of the steel when it is precipitated as precipitates or when it is dissolved in the matrix in the same manner as W. In the present invention, V in a content of less than 0.02% is insufficient for precipitation strengthening the steel with V precipitates, and on the other hand V in a content exceeding 1.00% forms clusters of V type carbides or carbonitrides which lower the toughness of the steel. Accordingly, the V content is defined to be from 0.02 to 1.00%.

Nb precipitates as NX type carbides or carbonitrides to increase the high temperature strength of the steel and contribute to solid solution strengthening. When the Nb content is less than 0.01%, the addition effects are not noticeable. When the Nb content exceeds 0.50%, coarse precipitates are formed to lower the toughness. Accordingly, the addition content range of Nb is defined to be from 0.01 to 0.50%.

N is dissolved in the matrix or precipitates as nitrides and carbonitrides. N contributes to solution hardening and precipitation hardening of the steel principally in the forms of VN, NbN or their carbonitrides. N in an addition content of less than 0.01% exhibits almost no contribution to strengthening of the steel. Moreover, the upper limit of the addition content thereof is defined to be 0.25% while the upper limit of the addition content thereof in molten steel in accordance with the Cr addition content of up to the maximum value of 18% is taken into consideration.

The addition of Ti, Zr, Ta and Hf constitutes the foundation of the present invention. The addition of these elements and the process according to the present invention realizes prevention of the "HAZ-softening" in the steel of the invention. Ti, Zr, Ta and Hf have an extremely strong affinity with C in the component system of the steel of the invention, and dissolve in M of M.sub.23 C.sub.6 as constituent elements to raise the decomposition temperature thereof. Accordingly, these elements are effective in preventing M.sub.23 C.sub.6 from coarsening in the "HAZ-softening" zone. In addition, these elements prevent W and Mo from dissolving in M.sub.23 C.sub.6, and, therefore, a zone depleted in W and Mo is not formed around the precipitates. These elements may be added singly or compositely in a mixture of at least two of them. These elements each in a content of at least 0.005% already show the effects. Since any one of these elements in a content of at least 2.0% forms coarse MX type carbides and deteriorates the toughness of the steel, the addition content range of each of them is defined to be from 0.005 to 2.0%.

P, S and O are mixed into the steel of the invention as impurities. However, in view of displaying the effect of the invention, P and S lower the strength, and O precipitates as an oxide and lowers the toughness of the steel. Accordingly, the upper limits of P, S and O are defined to be 0.03, 0.01 and 0.02%, respectively.

Though the fundamental components of the steel of the present invention are as described above, the steel of the invention may optionally contain one or at least two elements selected from the group consisting of Ni, Co and Cu. The steel of the invention may contain from 0.1 to 5.0% of Ni, from 0.1 to 5.0% of Co and from 0.1 to 2.0% of Cu.

Ni, Co and Cu are all potent elements for stabilizing austenite structure. Particularly when large amounts of ferrite-stabilizing elements, namely Cr, W, Mo, Ti, Zr, Ta, Hf, Si, etc., are added, Ni, Co, Cu are necessary for obtaining complete martensite or its tempered structure, and these elements are useful. At the same time, Ni and Co are effective in improving the toughness and the strength of the steel, respectively, and Cu is effective in improving the strength and corrosion resistance thereof. A content of each of these elements of less than 0.1% is insufficient for achieving these effects. When Ni or Co are each added in a content exceeding 5.0% or when Cu is added in a content exceeding 2.0%, it is inevitable that coarse intermetallic compounds are precipitated in the case of adding Ni or Co, and that intermetallic compounds are formed in a film form along grain boundaries in the case of adding Cu.

These elements are, therefore, added in the content ranges as mentioned above. However, since the above-mentioned effects of adding these elements become significant when they are each added in a content of at least 0.2%, the lower limit of the addition content of each of these elements is desirably 0.2%.

To obtain appropriate effects of adding Ti, Zr, Ta and Hf, the value of (Ti %+Zr %+Ta %+Hf %) in the metal component M of M.sub.23 C.sub.6 type carbides existing in the weld HAZ is required to be from 5 to 65%. To satisfy the requirement through precipitation of these elements in the form of appropriate carbides in the steel, the steel production process is carried out as follows: Ti, Zr, Ta and Hf are added during the period from 10 minutes before completion of refining to completion of refining; cooling the steel subsequent to solution treatment which is usually performed by holding the steel at temperature of 900.degree. to 1,350.degree. C. for a period of 10 minutes to 24 hours is temporarily stopped at a temperature from 950.degree. to 1,000.degree. C., and the steel is held at the temperature for a period of 5 to 60 minutes to control the precipitated forms of the carbides. The precipitates thus obtained can be utilized as precipitation nuclei of M.sub.23 C.sub.6 mainly containing Cr to be precipitated subsequent tempering, which is usually carried out by holding the steel at a temperature of 300.degree. to 850.degree. C. for a period of 10 minutes to 24 hours. The effects of adding Ti, Zr, Ta and Hf can be appropriately manifested and the object of the invention can be achieved only by applying the process as mentioned above. The intended effects of the present invention cannot be achieved even if a steel is produced merely by a conventional process using materials having the adjusted chemical composition of the invention. That is, the value of (Ti %+Zr %+Ta %+Hf %) in the metal component M of M.sub.23 C.sub.6 type carbides existing in the weld HAZ cannot be controlled to be from 5 to 65%.

The production process and the composition range of carbides as mentioned above have been determined by experiments as described below.

A molten steel having a chemical composition as claimed in the claims of the present invention except for Ti, Zr, Ta and Hf was prepared by using a VIM (vacuum induction heating furnace) or EF (electric furnace), and selecting and using an AOD (argon-oxygen blowing decarbonization refining unit), a VOD (vacuum exhausting oxygen blowing decarbonization unit) or LF (molten steel ladle refining unit), and cast into a slab having a cross section of 210.times.1,600 mm by a continuous casting unit. The influence of the addition time of Ti, Zr, Ta and Hf on the composition and the shape of precipitates after casting was investigated by adding these elements at any of the following times: at the start of melting, during melting or 5 minutes before completion of melting in a VIM or EF; at the start of refining process or 10 minutes before completion thereof in an AOD, a VOD or LF. Each of the slabs thus cast was sectioned so that each piece thus obtained had a length of 2 to 5 m and plates each having a thickness of 25.4 mm were formed. The plates were then solution treated under the conditions of the maximum heating temperature of 1,100.degree. C. and a holding time of 1 hour. In the course of cooling the plates, cooling was stopped at a temperature of 1,050.degree., 1,000.degree., 950.degree., 900.degree., 850.degree. or 800.degree. C., and the plates were held at the temperature for up to 24 hours in the furnace and air cooled. Precipitates in the plates were then subjected to residue-extraction analysis, and the precipitation forms of carbides in the plates were examined using a transmission electron microscope with a micro X-ray analysis apparatus.

Furthermore, each of the steel plates thus obtained was tempered at 780.degree. C. for 1 hour, subjected to edge preparation for V-shaped butt welding with a groove angle of 45 degrees, and used for welding experiments. The experiments were carried out by using TIG arc welding under a selected heat input condition of 15,000 J/cm which is a general heat input for martensitic heat-resisting materials.

The welded joint samples thus obtained were subjected to post weld heat treatment at 740.degree. C. for 6 hours, and thin film disc samples for transmission electron microscopic observation and block test pieces for extraction-residue analysis were sampled from the HAZ portions of the samples by procedures as shown in FIG. 2.

FIG. 3 shows the relationship between the addition time of Ti, Zr, Ta and Hf, and the form and the average particle size of precipitates of Ti, Zr, Ta and Hf in the steel. In order that the precipitates of Ti, Zr, Ta and Hf may become precipitation nuclei of M.sub.23 C.sub.6 and solid soluble in the constituent metal element M of M.sub.23 C.sub.6, these elements must exist as fine carbides (including carbonitrides) in advance in the molten metal. It is understood that to satisfy the requirement, these elements are required to be added to molten steel having a low oxygen concentration, that is, these elements must be added to molten steel during the period from 10 minutes before completion of refining in a VOD or LF to at the time of completion thereof. The average particle size of carbides at this time, namely carbides in steels produced by casting the molten steels or ingot-making thereof has been found to be approximately 0.15 .mu.m by electron microscopic observation of the carbides.

The particle size of the precipitates should desirably be made as small as possible in view of the precipitation strengthening mechanism.

When the cast slab, etc. thus obtained is subjected to hot working, solution treatment, cooling (air cooling) to room temperature, working and tempering, carbides of Ti, etc. precipitated in the tempered worked product become fine. However, the amount of the carbides thus formed is only about half as much as that of carbides of Ti, etc. having been precipitated in the slab at the time of its production. In addition, the carbides are precipitated as MC type carbides other than M.sub.23 C.sub.6 type carbides. As a result, the "HAZ-softening" phenomenon takes place in the tempered worked product.

As a result of investigating the relationship between cooling conditions after solution treatment and precipitated carbides using cast slabs (having chemical components the contents of which are in the range as claimed in the claims of the present invention) produced by the process of EF-LF-CC, the present inventors have clarified that the cooling stop temperature subsequent to solution treatment and the holding time at the temperature have an extremely important relationship with the particle size of the precipitated carbides.

That is, it has been confirmed that the average particle size of carbides precipitated in the steels becomes smallest when the cooling stop temperature and the holding temperature are from 950.degree. to 1,000.degree. C. and that most of the carbides having been precipitated in the cast slabs are reprecipitated when the slabs are held for a holding time of 5 to 60 minutes.

Taking the research results as described above into consideration, the present inventors carried out the following experiments: cast slabs, etc. used in FIG. 3 were worked, solution treated, subjected to air cooling which was stopped at a variety of temperatures including 950.degree. C. and 1,000.degree. C., held at respective cooling stop temperatures for 30 minutes, and further air cooled to room temperature; the samples thus obtained were tempered at 780.degree. C. for 1 hour; the samples were welded, and heat treated; and the relationship between the forms and compositions of the principal precipitates in the weld HAZ, and the cooling stop temperature was investigated. The results thus obtained are shown in FIG. 5. It is seen from FIG. 5 that the carbides which take the finest precipitation forms prior to tempering (carbides in the steels which have been subjected to cooling stop at a temperature of 950.degree. C. or 1,000.degree. C.) become precipitation nuclei of M.sub.23 C.sub.6, that the carbides and M.sub.23 C.sub.6 precipitated during tempering mutually dissolve in each other to finally form M.sub.23 C.sub.6 type carbides, and that Ti, Zr, Ta and Hf are dissolved in the constituent metal element M in a proportion of 5 to 65% in total.

Furthermore, it has been found that the weld HAZ as mentioned above has a very high creep rupture strength at high temperature.

FIG. 6 shows the relationship between a difference (D-CRS (MPa)) between the creep rupture strength of the base steels at 600.degree. C. for 100,000 hours and that of the weld HAZ, and the value of M % (Ti %+Zr %+Ta %+Hf %) in M.sub.23 C.sub.6 type carbides in the weld HAZ. When M % is from 5 to 65, the creep rupture strength of the weld HAZ decreases by only up to 7 MPa compared with that of the base steels. Since the difference is within the deviation of the creep rupture strength data of the base steels (10 MPa), it is understood that the weld HAZ no longer exhibits HAZ-softening. It can be concluded that the experimental results are brought about for the following reasons: M.sub.23 C.sub.6 type carbides containing from 5 to 65% of Ti, Zr, Ta and Hf in the constituent element M have a high decomposition temperature compared with ordinary M.sub.23 C.sub.6 type carbides containing mainly Cr in M, and are not subject to be coalescence coarsening even after weld heat affection; moreover, W and Mo are extremely difficult to dissolve in place of or in addition to Ti, Zr, Ta and Hf due to their chemical affinities and phase diagrams.

In addition, each of the elements Ti, Zr, Ta and Hf influences the creep strength of the base steels.

FIG. 7 shows the relationship between the creep rupture strength of the base steels at 600.degree. C. for 100,000 hours and the value of Ti %+Zr %+Ta %+Hf % in the base steels. It is evident from FIG. 7 that excessive addition of Ti, Zr, Ta and Hf causes precipitate coarsening, and that as a result the creep rupture strength of the base steels themselves decreases. When the total amount of Ti %+Zr %+Ta %+Hf % in the base steels is up to 8%, the creep rupture strength thereof becomes at least the evaluation standard value of 130 MPa and causes no problem. When the upper limit of the total amount of Ti, etc. is 8%, the content of each of the elements Ti, Zr, Ta and Hf does not exceed 2%, and is within the content range as claimed in the present invention.

Next, the toughness of the weld HAZ of the steel according to the present invention will be explained. FIG. 8 shows the relationship between the value of Ti %+Zr %+Ta %+Hf %, namely M % in M.sub.23 C.sub.6 in the weld HAZ and the toughness of the weld HAZ. It is understood from FIG. 8 that when M % exceeds 65%, the precipitates are coarsened and the toughness of the weld HAZ decreases, and that the toughness falls below the evaluation standard value of 50 J.

In addition, in the toughness test, a 2 mmV-notched Charpy impact test piece 11 in accordance with JIS No.4 was cut out of a portion containing a weld zone and located in the direction normal to the weld line as shown in FIG. 11(a) and FIG. 11(b). The notch was formed at a weld bond 9, which was represented by the hardest portion and shown. The evaluation standard value was defined to be 50 J at 0.degree. C. while the construction conditions of heat-resisting materials were taken into consideration. The reference numeral 10 designates a weld HAZ.

As described above, the steel of the invention having a value of 5 to 65% as M % is also excellent in toughness.

The process of the present invention has been determined as claimed in the claims on the basis of the results as mentioned above. When a steel having a chemical composition according to the present invention is produced without applying the process of the present invention, it is impossible to obtain in the weld HAZ M.sub.23 C.sub.6 carbides having the same composition as mentioned in the present invention.

There is no limitation on the method for melting the steel of the invention. The process can be determined in a satisfactory way taking into consideration converters, induction heating furnaces, arc melting furnaces, electric furnaces, etc., and chemical components and the cost of the steel. The unit used in the refining step is required to be equipped with a hopper which can add Ti, Zr, Ta and Hf and which is capable of controlling the oxygen concentration in the molten steel at a sufficiently low one so that at least 90% of these added elements can be precipitated as carbides. Accordingly, an LF equipped with an Ar-blowing unit, an arc heating unit or plasma heating unit, or a vacuum degassing unit is advantageously used. The use of them will enhance the effects of the invention.

Furthermore, in the subsequent rolling step or tube milling step in the case of producing a steel tube, solution treatment is essential for the purpose of uniformly redissolving the precipitates. There is required an installation capable of stopping the cooling of the steel at a given temperature in the course of cooling after solution treatment, and holding at that temperature, and a furnace which can heat the steel up to 1,350.degree. C. is required. There can be applied production steps other than those mentioned above, concretely, all production steps recognized as necessary or useful for producing a steel or a steel product by the present invention, for example, forging, rolling, heat treatment, tubing, welding, sectioning, inspection, and the like. Their application by no means impairs the effects of the present invention.

Particularly in the production of steel tubes, the following production processes of steel tubes can be applied to the present invention under the condition that the processes comprise the production steps of the present invention without fail: a process for producing a seamless pipe or tube comprising the steps of working a steel to form a round or square billet, and hot extruding or seamless rolling the billet in various ways; a process for producing an electric welded tube comprising the steps of hot rolling and cold rolling a steel sheet, and resistance welding the rolled sheet; and a process for producing a welded steel tube comprising carrying out TIG arc welding, MIG welding, SAW, LASER welding and EB welding singly or in combination. Furthermore, there can be additionally practiced after carrying out each of the processes as mentioned above any of hot or warm SR (squeeze rolling), sizing rolling, and a variety of levelling steps. The applicable size of the steel of the invention can thus be expanded.

The steel of the present invention may further be provided in the form of a plate or sheet. The plate or sheet having been subjected to necessary heat treatment may be used as a heat-resisting material with various shapes, and exerts no adverse effects in the present invention.

Still furthermore, there may be applied to the process of the present invention powder metallurgy processes such as HIP (hot isostatic press sintering unit), CIP (cold isostatic pressing unit) and sintering. Products having a variety of shapes can be obtained by subjecting the resultant compacted products to indispensable heat treatment.

The steel tubes, steel plates and heat-resisting steel materials of various shapes thus obtained may be subjected to respective heat treatments depending on the object and application. These heat treatments are important to obtain sufficient effects of the present invention.

Usually, the products of the invention are obtained through the steps of normalizing (solution treatment) and tempering. The products may further be retempered and/or normalized, and the step is useful. In addition, cooling stop at a temperature of the steel and holding it at the temperature after solution treatment are essential to the process of the invention.

When the steel of the invention has a relatively high content of nitrogen or carbon, when the steel contains austenite-stabilizing elements such as Co, Ni and Cu in a large amount or when the steel has a low Cr equivalent, the so-called sub-zero treatment wherein the steel is cooled to up to 0.degree. C. may be applied thereto to avoid retained austenite phase formation. The treatment is effective in sufficiently manifesting the mechanical properties of the steel of the invention.

Each of the steps mentioned above may also be applied at least twice so long as the repetition of the steps is necessary for sufficiently manifesting the material properties, and the repetition exerts no adverse effects in the present invention.

The steps as mentioned above may suitably be selected and applied to the process for producing the steel of the present invention.

EXAMPLES

A molten steel having components except for Ti, Zr, Ta and Hf as shown in some of Table 1-1 to Table 25-3 was prepared in an amount of 300 ton, 120 ton or 60 ton by the blast furnace pig iron-converter blowing process, using a VIM or EF, and refined in an LF unit having an arc reheating unit and capable of blowing Ar. At least one of the elements Ti, Zr, Ta and Hf was added to the molten steel in amounts as shown in the table 10 minutes before completion of refining, and the molten steel was continuously cast to obtain a slab. The slab thus obtained was hot rolled to give a plate 50 mm thick and a sheet 12 mm thick, or the slab was worked to give a round billet which was hot extruded to give a tube having an outer diameter of 74 mm and a thickness of 10 mm or which was seamless rolled to give a pipe having an outer diameter of 380 mm and a thickness of 50 mm. The sheet was formed, and electric welded to give an electric welded steel tube having an outer diameter of 280 mm and a thickness of 12 mm.

All the plates, sheets and tubes thus obtained were solution treated at 1,100.degree. C. for 1 hour, subjected to a temporary cooling stop at a temperature of 950.degree. to 1,000.degree. C. and held at that temperature for 5 to 60 minutes in the furnace, air cooled, and tempered at 780.degree. C. for 1 hour.

The plates and sheets thus obtained were subjected to edge preparation exactly in the same manner as shown in FIG. 1. A groove which was the same as in FIG. 1 was formed in each of the tubes thus obtained at the edge in the circumferential direction. The worked plates and sheets were welded and the worked tubes were subjected to circular joint welding, by TIG arc welding or SAW welding. All the welded portions were locally subjected to softening annealing (PWHT) by heating them at 740.degree. C. for 6 hours.

The creep characteristics of the base steels were obtained as follows: a creep test piece 5 having a diameter of 6 mm was cut out of a portion other than a weld zone and a weld HAZ in a steel tube 1 in the direction parallel to the tube axis direction 2 as shown in FIG. 9(a), or a creep test piece 5 of the same size was cut out of the same portion as mentioned above in a plate 3 in the direction parallel to the rolling direction 4 as shown in FIG. 9(b); a creep rupture strength was measured at 600.degree. C. on the test piece, and the data thus obtained were linearly extrapolated to obtain a creep rupture strength for 100,000 hours. The creep characteristics of a weld zone was obtained as follows: a creep rupture test piece 8 having a diameter of 6 mm was cut out of each of the welded tubes or plates in a direction 7 normal to a weld line 6 as shown in FIG. 10(a) or FIG. 10(b); the results of measuring creep rupture strength at 600.degree. C. were linearly extrapolated to 100,000 hours. The creep characteristics thus obtained were compared with those of the base steels and evaluated. For convenience of description in the present invention, a "creep rupture strength" (HAZCRS (MPa)) signifies a creep rupture strength at 600.degree. C. for 100,000 hours estimated by linear extrapolation. A difference between the creep rupture strength of a base steel and that of a weld HAZ (D-CRS (MPa)) was used as an index of the "HAZ-softening" resistance of a weld zone. Although the value of D-CRS is somewhat influenced by the method of sampling a creep rupture test piece in the rolling direction of a sample, it has been empirically found by a preliminary experiment that the influence is within 5 MPa. Accordingly, a D-CRS value of up to 10 MPa signifies that the HAZ-softening resistance of the steel material is extremely good.

Test pieces for precipitates of a HAZ portion were sampled by the procedure as shown in FIG. 2, and subjected to extraction-residue analysis by acid dissolution to identify M.sub.23 C.sub.6, followed by determining the composition in M by a scanning type micro X-ray analysis apparatus. Ti %+Zr %+Ta %+Hf % thus obtained were represented by M %, and the precipitates were evaluated. The standard reference based on the experimental results is defined to be from 5 to 65%.

The values of D-CRS, HAZCRS and M % were shown in Table 1-3, Table 2-3 to Table 25-3 in the form of numerical data together with chemical components.

It is evident from the tables that the steels of the present invention No. 1 to No. 381 exhibited the maximum value of D-CRS of 7 MPa, the maximum value of HAZCRS of 180 MPa and the minimum value of HAZCRS of 130 MPa. Accordingly, the HAZ-softening resistance of the steels of the invention was extremely good.

For comparison, steels which did not correspond to any of the claims of the present invention were evaluated in the same manner. The chemical components and the values of D-CRS, HAZCRS and M % among the evaluation results are shown in Table 26-1 to Table 26-2.

Experimental results about comparative steels in Table 26-1 to Table 26-2 are as described below. Though No. 721 steel and No. 722 steel had the same chemical components as the steel of the invention, Ti and Zr were added at the time of melting. As a result, the value of M % became up to 5%, and the HAZ-softening resistance deteriorated. In No. 723 steel and No. 724 steel, Ti, Zr, Ta and Hf were not sufficiently added. As a result, M % became low, and the HAZ-softening resistance deteriorated. No. 725 steel, No. 726 steel, No. 727 steel and No. 728 steel were instances wherein a number of coarse MX type carbides were precipitated, composition control of M.sub.23 C.sub.6 in the weld HAZ could not be achieved, and as a result the HAZ-softening resistance deteriorated, due to excessive addition of Ti in the case of No. 725 steel, excessive addition of Zr in the case of No. 726 steel, excessive addition of Ta in the case of No. 727 steel and excessive addition of Hf in the case of No. 728 steel. Since a temporary cooling stop was not practiced after solution treatment in the production of No. 729 steel, composition control of M.sub.23 C.sub.6 therein could not be achieved, and the HAZ-softening resistance deteriorated. In the production of No. 730 steel, since the holding time was 240 minutes which was overly long after solution treatment and the temporary cooling stop, the precipitates therein were coarsened, and composition control of M.sub.23 C.sub.6 could not be achieved. As a result, the HAZ-softening resistance deteriorated.

TABLE 1-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________1 0.26 0.24 0.46 16.73 0.753 1.88 0.69 0.33 0.172 0.24 0.63 0.68 16.40 0.126 0.92 0.44 0.44 0.033 0.05 0.30 0.69 15.19 0.120 2.65 0.68 0.40 0.214 0.06 0.29 0.79 11.23 0.082 1.57 0.26 0.11 0.205 0.10 0.48 0.84 8.84 0.841 2.08 0.50 0.49 0.086 0.25 0.74 0.70 12.33 0.250 0.38 0.26 0.48 0.057 0.18 0.16 0.25 13.11 0.128 2.48 0.35 0.47 0.078 0.14 0.56 0.55 15.41 0.301 2.87 0.60 0.15 0.109 0.06 0.24 0.67 17.20 0.625 2.72 0.87 0.41 0.1010 0.20 0.27 0.47 9.83 0.427 1.44 0.50 0.44 0.15______________________________________ TABLE 1-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________1 1.790 -- -- -- -- -- --2 1.816 -- -- -- -- -- --3 0.952 -- -- -- -- -- --4 0.843 -- -- -- -- -- --5 1.168 -- -- -- -- -- --6 1.617 -- -- -- -- -- --7 -- 1.597 -- -- -- -- --8 -- 1.940 -- -- -- -- --9 -- 0.310 -- -- -- -- --10 -- 1.352 -- -- -- -- --______________________________________ TABLE 1-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________1 0.0259 0.002 0.012 2 170 192 0.0013 0.002 0.003 2 135 263 0.0239 0.005 0.003 3 164 184 0.0151 0.004 0.018 4 133 155 0.0287 0.003 0.007 0 172 196 0.0155 0.008 0.015 1 158 247 0.0003 0.002 0.019 2 168 208 0.0229 0.003 0.006 1 180 209 0.0190 0.003 0.012 1 171 1610 0.0280 0.004 0.014 2 171 20______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 2-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________11 0.22 0.49 0.64 17.23 0.050 3.46 0.30 0.41 0.2112 0.22 0.41 0.63 17.66 0.814 3.30 0.13 0.48 0.2413 0.15 0.28 0.32 15.59 0.078 2.05 0.79 0.07 0.0914 0.10 0.75 0.78 8.84 0.157 0.82 0.17 0.09 0.1915 0.17 0.52 0.67 14.68 0.395 2.36 0.55 0.47 0.1516 0.18 0.26 0.26 5.12 0.130 1.20 0.31 0.37 0.0417 0.07 0.21 0.22 10.58 0.199 1.75 0.27 0.46 0.1918 0.22 0.64 0.42 9.12 0.924 3.43 0.74 0.17 0.1919 0.17 0.64 0.73 11.97 0.665 0.80 0.11 0.15 0.1320 0.15 0.10 0.63 16.90 0.246 3.19 0.18 0.32 0.0921 0.25 0.03 0.36 15.00 0.487 1.78 0.76 0.35 0.1522 0.15 0.32 0.21 17.52 0.755 2.72 0.26 0.18 0.0223 0.07 0.46 0.84 15.56 0.858 0.42 0.45 0.44 0.0424 0.13 0.31 0.93 7.19 0.653 2.65 0.21 0.33 0.1525 0.13 0.53 0.34 16.17 0.961 0.58 0.34 0.24 0.0926 0.15 0.57 0.92 14.13 0.114 0.25 0.18 0.35 0.1627 0.02 0.74 0.08 12.43 0.972 1.21 0.10 0.35 0.2228 0.13 0.50 0.76 8.64 0.356 2.86 0.41 0.38 0.2229 0.12 0.51 0.94 7.18 0.102 1.35 0.44 0.36 0.2530 0.10 0.24 0.59 12.46 0.044 2.76 0.54 0.23 0.0231 0.03 0.73 0.37 15.70 0.017 1.57 0.54 0.13 0.0932 0.28 0.31 0.95 8.42 0.864 2.23 0.29 0.25 0.1933 0.24 0.40 0.20 7.98 0.920 2.52 0.60 0.24 0.1534 0.14 0.09 0.79 5.65 0.518 1.92 0.34 0.04 0.1835 0.23 0.43 1.00 12.41 0.496 3.17 0.80 0.04 0.1236 0.17 0.50 0.68 13.01 0.682 2.41 0.85 0.17 0.1737 0.05 0.57 0.50 11.87 0.915 2.43 0.81 0.36 0.1638 0.27 0.13 0.34 13.42 0.051 2.69 0.55 0.02 0.0639 0.05 0.21 0.87 8.96 0.896 2.65 0.86 0.06 0.0740 0.21 0.29 0.75 9.27 0.298 3.37 0.10 0.16 0.04______________________________________ TABLE 2-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________11 -- 1.738 -- -- -- -- --12 -- 1.155 -- -- -- -- --13 0.139 1.257 -- -- -- -- --14 1.612 1.716 -- -- -- -- --15 1.252 0.233 -- -- -- -- --16 1.732 0.455 -- -- -- -- --17 1.697 0.052 -- -- -- -- --18 0.825 1.705 -- -- -- -- --19 -- -- 0.095 -- -- -- --20 -- -- 0.340 -- -- -- --21 -- -- 0.989 -- -- -- --22 -- -- 0.779 -- -- -- --23 -- -- 1.339 -- -- -- --24 -- -- 0.354 -- -- -- --25 0.981 -- 0.498 -- -- -- --26 1.649 -- 1.420 -- -- -- --27 0.561 -- 1.818 -- -- -- --28 1.351 -- 1.373 -- -- -- --29 1.702 -- 1.729 -- -- -- --30 1.288 -- 1.569 -- -- -- --31 -- 0.689 0.535 -- -- -- --32 -- 1.635 1.354 -- -- -- --33 -- 0.709 0.668 -- -- -- --34 -- 1.582 1.156 -- -- -- --35 -- 1.931 0.482 -- -- -- --36 -- 1.429 0.321 -- -- -- --37 1.355 1.736 1.335 -- -- -- --38 1.996 1.543 0.220 -- -- -- --39 0.922 0.512 0.631 -- -- -- --40 1.786 1.310 0.238 -- -- -- --______________________________________ TABLE 2-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________11 0.0156 0.009 0.009 1 156 2512 0.0214 0.008 0.014 5 154 1613 0.0106 0.008 0.015 5 143 2214 0.0232 0.003 0.019 4 175 3415 0.0246 0.001 0.013 1 179 1816 0.0248 0.005 0.004 2 156 3117 0.0037 0.004 0.016 5 135 2018 0.0163 0.001 0.010 5 144 2619 0.0278 0.005 0.020 2 135 820 0.0183 0.003 0.004 5 136 821 0.0129 0.009 0.007 6 150 1422 0.0218 0.007 0.007 4 154 1223 0.0247 0.010 0.001 4 177 2024 0.0023 0.002 0.014 2 170 1025 0.0090 0.004 0.006 0 162 1726 0.0251 0.007 0.010 4 155 3727 0.0161 0.004 0.015 3 152 2628 0.0067 0.006 0.007 6 131 3529 0.0219 0.009 0.013 0 145 3830 0.0264 0.001 0.009 7 146 3031 0.0163 0.004 0.012 6 162 1732 0.0160 0.003 0.019 2 146 2833 0.0207 0.009 0.008 2 175 2434 0.0255 0.008 0.014 3 178 2635 0.0107 0.007 0.004 0 131 2736 0.0157 0.005 0.004 2 164 2137 0.0061 0.009 0.012 4 177 4138 0.0221 0.008 0.014 2 150 3439 0.0284 0.002 0.008 1 135 2940 0.0056 0.003 0.019 5 159 32______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M % : Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 3-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________41 0.27 0.25 0.24 12.41 0.100 1.06 0.10 0.22 0.0342 0.05 0.35 0.43 16.05 0.123 1.77 0.19 0.18 0.0143 0.06 0.46 0.38 11.75 0.713 1.63 0.70 0.44 0.0744 0.26 0.45 0.74 10.09 0.699 1.78 0.50 0.19 0.1545 0.18 0.20 0.21 15.83 0.436 1.69 0.40 0.08 0.1246 0.05 0.36 0.65 13.54 0.736 2.41 0.24 0.26 0.1547 0.26 0.40 0.31 7.68 0.945 1.81 0.84 0.20 0.1048 0.04 0.60 0.69 15.73 0.411 0.98 0.58 0.27 0.1749 0.21 0.05 0.43 9.45 0.950 1.03 0.26 0.41 0.1950 0.15 0.17 0.21 12.60 0.411 3.05 0.23 0.30 0.2551 0.09 0.45 0.71 16.81 0.629 3.25 0.81 0.08 0.0652 0.13 0.37 0.58 13.24 0.932 1.02 0.36 0.43 0.0853 0.09 0.19 0.50 6.30 0.161 2.45 0.68 0.02 0.2454 0.19 0.17 0.72 13.28 0.645 0.39 0.15 0.01 0.1755 0.26 0.59 0.34 6.17 0.724 0.89 0.07 0.08 0.0656 0.23 0.12 0.41 8.81 0.740 1.79 0.78 0.13 0.2357 0.22 0.21 0.89 12.55 0.029 2.54 0.64 0.10 0.1658 0.17 0.74 0.97 15.27 0.420 0.94 0.48 0.15 0.1759 0.18 0.79 0.41 8.33 0.251 1.40 0.61 0.19 0.2260 0.20 0.64 0.57 9.10 0.855 3.36 0.89 0.39 0.0461 0.19 0.52 0.93 8.94 0.576 1.37 0.17 0.18 0.0662 0.09 0.72 0.55 5.73 0.246 1.46 0.74 0.22 0.1263 0.01 0.32 0.91 10.33 0.696 3.09 0.96 0.42 0.0764 0.04 0.37 0.28 7.70 0.776 2.45 0.69 0.22 0.1065 0.14 0.73 0.52 8.57 0.808 2.26 0.24 0.26 0.0666 0.11 0.50 0.29 10.86 0.136 1.99 0.94 0.23 0.0367 0.04 0.33 0.68 5.87 0.583 2.73 0.64 0.04 0.2068 0.19 0.49 0.74 17.63 0.505 0.69 0.67 0.34 0.1869 0.07 0.06 0.75 17.85 0.223 1.86 0.86 0.08 0.0570 0.20 0.46 0.56 17.30 0.563 2.43 0.56 0.16 0.24______________________________________ TABLE 3-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________41 1.270 0.627 0.732 -- -- -- --42 1.055 0.131 0.780 -- -- -- --43 -- -- -- 1.282 -- -- --44 -- -- -- 1.087 -- -- --45 -- -- -- 1.833 -- -- --46 -- -- -- 1.168 -- -- --47 -- -- -- 1.763 -- -- --48 -- -- -- 0.323 -- -- --49 0.239 -- -- 0.471 -- -- --50 0.589 -- -- 0.930 -- -- --51 0.276 -- -- 0.342 -- -- --52 1.979 -- -- 1.398 -- -- --53 0.346 -- -- 1.758 -- -- --54 0.098 -- -- 0.098 -- -- --55 -- 1.453 -- 1.079 -- -- --56 -- 1.997 -- 0.375 -- -- --57 -- 1.774 -- 0.651 -- -- --58 -- 0.499 -- 0.599 -- -- --59 -- 1.816 -- 1.869 -- -- --60 -- 1.395 -- 1.144 -- -- --61 -- -- 1.682 1.102 -- -- --62 -- -- 1.723 0.420 -- -- --63 -- -- 1.419 1.755 -- -- --64 -- -- 1.434 0.781 -- -- --65 -- -- 0.457 0.180 -- -- --66 -- -- 1.131 1.596 -- -- --67 -- 1.565 0.174 0.751 -- -- --68 -- 0.516 1.211 0.262 -- -- --69 -- 1.779 1.935 1.829 -- -- --70 -- 0.041 1.021 0.130 -- -- --______________________________________ TABLE 3-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________41 0.0084 0.008 0.004 4 176 2642 0.0168 0.003 0.002 2 163 2343 0.0111 0.010 0.006 4 173 2444 0.0161 0.002 0.006 1 133 1945 0.0272 0.003 0.006 1 172 2346 0.0091 0.002 0.005 0 142 2247 0.0023 0.010 0.008 7 170 2748 0.0016 0.007 0.003 1 160 1049 0.0170 0.003 0.006 6 140 1550 0.0142 0.003 0.004 4 136 1751 0.0175 0.003 0.003 0 177 1552 0.0076 0.005 0.011 0 166 3553 0.0093 0.007 0.004 0 179 2554 0.0026 0.004 0.009 2 171 755 0.0275 0.007 0.012 1 168 2656 0.0193 0.003 0.011 3 149 2957 0.0179 0.002 0.002 1 141 2658 0.0034 0.003 0.020 2 171 1659 0.0158 0.005 0.005 3 169 3360 0.0205 0.002 0.001 6 160 3261 0.0272 0.005 0.016 7 174 3162 0.0167 0.005 0.017 4 162 2863 0.0132 0.005 0.020 6 178 3464 0.0122 0.002 0.003 6 149 3165 0.0088 0.009 0.019 2 178 1566 0.0128 0.002 0.020 7 168 3067 0.0196 0.006 0.019 6 147 2568 0.0090 0.003 0.005 5 142 2669 0.0065 0.008 0.003 6 130 5270 0.0216 0.002 0.009 1 141 23______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 4-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________71 0.12 0.04 0.47 14.15 0.389 1.88 0.59 0.25 0.2572 0.06 0.58 0.71 12.41 0.506 1.27 0.79 0.02 0.0273 0.26 0.03 0.80 16.86 0.283 1.78 0.03 0.14 0.1374 0.10 0.21 0.56 12.06 0.531 2.80 0.59 0.03 0.0575 0.25 0.60 0.29 9.07 0.105 0.55 0.35 0.34 0.2276 0.09 0.29 0.25 12.17 0.327 2.70 0.62 0.26 0.2477 0.29 0.70 0.30 12.77 0.044 0.48 0.26 0.45 0.0878 0.08 0.55 0.72 15.14 0.576 1.57 0.57 0.08 0.0579 0.29 0.10 0.58 10.74 0.275 0.50 0.91 0.31 0.2480 0.28 0.77 0.53 16.79 0.957 1.65 0.13 0.31 0.1281 0.30 0.10 0.45 11.82 0.476 1.20 0.04 0.01 0.1382 0.15 0.69 0.62 6.58 0.663 0.27 0.47 0.31 0.1283 0.08 0.46 0.89 11.99 0.845 1.58 0.77 0.38 0.0584 0.19 0.45 0.74 12.88 0.373 1.33 0.29 0.41 0.2485 0.28 0.15 0.43 7.25 0.577 0.62 0.35 0.30 0.0486 0.16 0.22 0.65 12.39 0.792 2.21 0.29 0.22 0.1587 0.08 0.12 0.84 13.14 0.855 2.25 0.93 0.34 0.1588 0.12 0.13 0.90 13.94 0.605 1.85 0.15 0.32 0.0289 0.25 0.11 0.66 12.44 0.861 0.44 0.72 0.10 0.1890 0.12 0.34 0.43 13.31 0.983 2.49 0.05 0.31 0.1291 0.26 0.27 0.44 7.63 0.289 2.44 0.40 0.16 0.1792 0.21 0.19 0.59 13.01 0.619 3.10 0.66 0.29 0.0493 0.04 0.74 0.33 14.16 0.316 0.61 0.16 0.37 0.0594 0.01 0.63 0.33 15.50 0.214 2.69 0.70 0.34 0.0595 0.21 0.11 0.47 8.31 0.632 0.49 0.16 0.09 0.1196 0.16 0.61 0.60 16.59 0.924 1.80 0.34 0.06 0.0897 0.25 0.07 0.21 5.61 0.424 1.06 0.59 0.14 0.0398 0.28 0.30 0.36 5.85 0.466 2.76 0.28 0.03 0.0599 0.21 0.80 0.53 8.72 0.893 1.38 0.69 0.38 0.21100 0.27 0.64 0.97 11.99 0.537 2.95 0.20 0.37 0.12______________________________________ TABLE 4-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________71 -- 0.959 0.136 0.829 -- -- --72 -- 0.207 1.931 0.576 -- -- --73 1.690 -- 0.124 1.077 -- -- --74 1.669 -- 1.346 1.982 -- -- --75 1.132 -- 0.292 0.976 -- -- --76 0.733 -- 1.636 0.741 -- -- --77 1.144 -- 1.047 0.932 -- -- --78 1.047 -- 0.175 1.207 -- -- --79 1.103 1.777 -- 0.273 -- -- --80 1.962 1.910 -- 1.785 -- -- --81 1.337 1.417 -- 0.404 -- -- --82 0.868 0.962 -- 0.806 -- -- --83 1.253 0.256 -- 0.676 -- -- --84 1.139 0.928 -- 1.675 -- -- --85 0.236 0.671 0.100 0.467 -- -- --86 1.171 0.156 0.291 0.738 -- -- --87 0.654 0.051 0.247 1.156 -- -- --88 1.329 1.029 0.669 0.394 -- -- --89 0.872 1.763 0.209 0.132 -- -- --90 1.956 1.935 1.548 1.028 -- -- --91 1.262 -- -- -- 0.63 -- --92 1.455 -- -- -- 4.01 -- --93 1.218 -- -- -- 3.88 -- --94 0.200 -- -- -- 1.89 -- --95 0.077 -- -- -- 2.04 -- --96 1.534 -- -- -- 1.15 -- --97 -- 1.537 -- -- 3.24 -- --98 -- 0.293 -- -- 2.57 -- --99 -- 0.537 -- -- 3.35 -- --100 -- 0.912 -- -- 2.34 -- --______________________________________ TABLE 4-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________71 0.0049 0.001 0.012 7 150 2372 0.0109 0.005 0.008 0 137 3373 0.0202 0.006 0.013 6 179 3574 0.0126 0.005 0.004 4 154 4975 0.0286 0.003 0.008 4 138 3076 0.0031 0.003 0.002 6 136 3877 0.0058 0.010 0.002 1 149 2978 0.0171 0.002 0.015 5 156 2479 0.0022 0.002 0.017 7 160 3580 0.0009 0.003 0.017 2 163 4981 0.0081 0.004 0.019 2 142 3082 0.0195 0.007 0.003 4 176 3383 0.0295 0.008 0.002 3 142 2884 0.0188 0.004 0.013 4 168 4185 0.0119 0.007 0.006 3 131 2286 0.0194 0.002 0.005 2 160 3187 0.0208 0.002 0.017 3 157 3088 0.0118 0.010 0.011 3 175 3589 0.0024 0.005 0.001 2 167 3790 0.0171 0.010 0.005 1 135 5991 0.0213 0.008 0.018 5 157 1792 0.0254 0.008 0.009 5 161 1793 0.0089 0.008 0.004 4 175 1694 0.0272 0.006 0.019 5 151 795 0.0007 0.007 0.002 7 167 896 0.0140 0.007 0.009 0 176 1997 0.0172 0.002 0.015 2 155 2498 0.0202 0.007 0.019 1 133 1099 0.0036 0.007 0.009 2 161 12100 0.0073 0.003 0.008 5 168 16______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 5-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________101 0.14 0.08 0.75 6.87 0.220 1.96 0.61 0.40 0.11102 0.20 0.19 0.95 11.03 0.298 2.89 0.29 0.41 0.12103 0.11 0.04 0.64 9.24 0.601 1.85 0.55 0.05 0.24104 0.26 0.67 0.88 5.76 0.456 1.61 0.25 0.01 0.19105 0.17 0.39 0.34 11.41 0.206 3.27 0.20 0.18 0.17106 0.07 0.27 0.49 17.82 0.686 1.33 0.24 0.48 0.14107 0.21 0.53 0.40 16.09 0.733 0.25 0.71 0.11 0.19108 0.26 0.30 0.73 17.14 0.675 1.06 0.46 0.19 0.14109 0.16 0.59 0.56 12.45 0.852 1.59 0.80 0.43 0.21110 0.17 0.12 0.55 6.22 0.109 1.35 0.11 0.23 0.12111 0.22 0.72 0.58 16.08 0.273 1.42 0.66 0.01 0.17112 0.27 0.29 0.51 7.19 0.686 2.91 0.35 0.43 0.23113 0.29 0.68 0.22 10.02 0.682 1.98 0.48 0.43 0.24114 0.21 0.18 0.37 9.45 0.098 1.38 0.89 0.41 0.16115 0.28 0.22 0.82 9.57 0.754 0.54 0.91 0.04 0.21116 0.16 0.68 0.64 14.96 0.993 0.59 0.41 0.23 0.20117 0.24 0.26 0.92 10.54 0.173 1.03 0.20 0.17 0.24118 0.04 0.79 0.31 7.23 0.613 2.93 0.60 0.26 0.04119 0.09 0.57 0.28 15.69 0.146 0.81 0.96 0.18 0.04120 0.06 0.27 0.71 8.04 0.121 0.75 0.16 0.09 0.20121 0.03 0.13 0.65 14.25 0.842 0.46 0.45 0.40 0.23122 0.25 0.02 0.78 6.38 0.170 2.77 0.71 0.29 0.23123 0.10 0.22 0.56 14.90 0.439 2.21 0.30 0.18 0.15124 0.25 0.22 0.69 5.34 0.500 3.21 0.05 0.24 0.19125 0.08 0.66 0.62 14.29 0.666 0.21 0.74 0.13 0.20126 0.11 0.23 0.20 7.25 0.295 2.62 0.28 0.26 0.13127 0.02 0.77 0.52 14.51 0.203 3.28 0.46 0.07 0.19128 0.03 0.58 0.25 7.90 0.724 3.29 0.63 0.21 0.21129 0.26 0.71 0.84 17.89 0.210 0.46 0.14 0.36 0.03130 0.21 0.64 0.58 9.84 0.986 2.52 0.78 0.18 0.11______________________________________ TABLE 5-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________101 -- 0.140 -- -- 1.17 -- --102 -- 1.860 -- -- 3.80 -- --103 1.404 1.731 -- -- 4.68 -- --104 1.667 1.445 -- -- 3.01 -- --105 0.575 1.664 -- -- 0.40 -- --106 1.760 0.058 -- -- 3.27 -- --107 1.915 0.313 -- -- 3.63 -- --108 1.701 1.081 -- -- 0.65 -- --109 -- -- 1.638 -- 0.80 -- --110 -- -- 1.980 -- 0.86 -- --111 -- -- 0.209 -- 4.82 -- --112 -- -- 1.014 -- 4.72 -- --113 -- -- 1.072 -- 2.21 -- --114 -- -- 0.075 -- 1.31 -- --115 1.592 -- 0.651 -- 3.56 -- --116 0.673 -- 0.501 -- 3.42 -- --117 1.451 -- 0.278 -- 2.48 -- --118 0.584 -- 1.652 -- 2.31 -- --119 1.764 -- 1.303 -- 2.20 -- --120 1.626 -- 1.925 -- 1.37 -- --121 -- 1.168 0.162 -- 3.77 -- --122 -- 0.784 1.701 -- 3.87 -- --123 -- 0.018 0.215 -- 0.84 -- --124 -- 1.470 0.326 -- 1.03 -- --125 -- 0.880 0.754 -- 1.34 -- --126 -- 0.911 0.183 -- 3.44 -- --127 1.756 1.252 0.281 -- 1.69 -- --128 0.436 1.545 0.696 -- 4.86 -- --129 0.861 1.463 1.103 -- 4.96 -- --130 1.714 0.693 1.188 -- 3.68 -- --______________________________________ TABLE 5-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________101 0.0264 0.004 0.006 5 157 8102 0.0258 0.001 0.007 5 155 21103 0.0011 0.002 0.010 6 164 39104 0.0216 0.004 0.019 0 164 22105 0.0080 0.002 0.005 5 155 22106 0.0298 0.008 0.010 0 167 23107 0.0228 0.007 0.014 3 177 30108 0.0264 0.006 0.003 6 162 33109 0.0060 0.004 0.012 6 151 25110 0.0016 0.004 0.019 1 146 24111 0.0229 0.010 0.002 5 174 10112 0.0058 0.009 0.015 0 139 17113 0.0199 0.006 0.007 0 143 22114 0.0155 0.009 0.005 6 164 12115 0.0024 0.001 0.013 4 155 31116 0.0209 0.009 0.010 6 168 15117 0.0208 0.004 0.012 7 132 26118 0.0271 0.003 0.005 3 149 28119 0.0205 0.004 0.017 3 146 29120 0.0107 0.010 0.015 0 152 39121 0.0227 0.001 0.014 6 168 21122 0.0219 0.009 0.003 1 174 27123 0.0029 0.008 0.006 4 171 16124 0.0205 0.002 0.001 1 137 27125 0.0256 0.003 0.015 7 151 26126 0.0134 0.005 0.005 5 164 16127 0.0234 0.006 0.016 5 155 38128 0.0210 0.005 0.018 6 151 26129 0.0158 0.005 0.005 0 131 35130 0.0185 0.009 0.004 7 146 37______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 6-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________131 0.14 0.64 0.53 7.51 0.891 2.28 0.93 0.09 0.03132 0.13 0.55 0.55 15.34 0.760 0.90 0.91 0.49 0.12133 0.28 0.28 0.92 11.68 0.928 2.74 0.07 0.09 0.21134 0.26 0.06 0.70 7.24 0.721 0.67 0.70 0.02 0.04135 0.16 0.18 0.56 6.61 0.491 2.41 0.19 0.20 0.03136 0.22 0.10 0.77 14.08 0.069 2.49 0.35 0.08 0.03137 0.12 0.10 0.81 14.55 0.288 0.33 0.52 0.05 0.25138 0.23 0.04 0.54 12.41 0.988 0.38 0.05 0.03 0.03139 0.23 0.20 0.63 5.54 0.016 2.09 0.74 0.20 0.07140 0.05 0.04 0.94 11.20 0.684 3.25 0.95 0.46 0.20141 0.24 0.61 0.95 14.26 0.833 1.64 0.54 0.25 0.15142 0.01 0.61 0.52 6.09 0.811 3.37 0.79 0.22 0.22143 0.06 0.30 0.33 17.26 0.956 1.30 0.10 0.30 0.04144 0.18 0.35 0.64 12.88 0.093 1.45 0.25 0.15 0.02145 0.04 0.62 0.93 10.57 0.068 1.69 0.12 0.20 0.15146 0.03 0.20 0.26 8.05 0.211 1.43 0.50 0.11 0.25147 0.09 0.12 0.89 9.42 0.336 1.72 0.26 0.03 0.04148 0.18 0.65 0.29 6.32 0.302 0.45 0.70 0.15 0.10149 0.11 0.12 0.34 9.76 0.454 0.40 0.71 0.38 0.13150 0.12 0.34 0.92 17.51 0.620 1.00 0.11 0.16 0.10151 0.02 0.79 0.27 14.38 0.136 1.70 0.70 0.37 0.09152 0.19 0.56 0.68 11.14 0.818 0.27 0.35 0.21 0.18153 0.16 0.31 0.81 5.80 0.037 1.20 0.39 0.33 0.10154 0.01 0.68 0.93 15.75 0.107 0.60 0.16 0.15 0.03155 0.15 0.39 0.51 12.78 0.363 1.23 0.95 0.34 0.18156 0.08 0.07 0.21 7.67 0.645 0.90 0.67 0.32 0.16157 0.04 0.78 0.32 17.99 0.293 0.72 0.61 0.26 0.16158 0.29 0.04 0.68 15.40 0.139 3.45 0.62 0.08 0.15159 0.18 0.07 0.38 10.97 0.022 0.30 0.04 0.18 0.20160 0.27 0.35 0.89 8.87 0.266 0.63 0.67 0.24 0.15______________________________________ TABLE 6-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________131 0.647 1.902 1.623 -- 4.99 -- --132 1.348 1.760 0.077 -- 3.27 -- --133 -- -- -- 0.962 4.97 -- --134 -- -- -- 1.168 4.50 -- --135 -- -- -- 1.762 1.05 -- --136 -- -- -- 0.437 3.44 -- --137 -- -- -- 1.831 1.30 -- --138 -- -- -- 0.643 1.01 -- --139 0.032 -- -- 0.561 4.23 -- --140 0.020 -- -- 1.225 0.56 -- --141 0.800 -- -- 0.314 3.59 -- --142 0.091 -- -- 1.513 0.57 -- --143 0.542 -- -- 1.455 2.60 -- --144 1.809 -- -- 1.849 1.78 -- --145 -- 1.395 -- 1.367 4.55 -- --146 -- 0.851 -- 0.674 0.52 -- --147 -- 1.029 -- 0.440 0.85 -- --148 -- 1.604 -- 0.336 4.77 -- --149 -- 1.249 -- 0.028 4.27 -- --150 -- 1.610 -- 1.176 0.97 -- --151 -- -- 1.696 0.475 1.32 -- --152 -- -- 0.524 1.620 4.58 -- --153 -- -- 0.473 0.262 0.29 -- --154 -- -- 1.208 1.053 2.06 -- --155 -- -- 1.419 0.689 1.93 -- --156 -- -- 1.769 0.830 1.48 -- --157 -- 1.492 0.925 1.141 2.35 -- --158 -- 0.991 1.568 0.313 1.35 -- --159 -- 1.284 1.367 0.995 4.86 -- --160 -- 0.032 1.984 1.878 4.93 -- --______________________________________ TABLE 6-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________131 0.0237 0.006 0.003 0 174 1132 0.0266 0.004 0.006 0 143 36133 0.0078 0.006 0.013 3 132 16134 0.0215 0.007 0.018 3 167 14135 0.0033 0.004 0.001 7 177 25136 0.0231 0.004 0.015 5 139 17137 0.0011 0.008 0.019 5 131 26138 0.0072 0.004 0.010 5 180 17139 0.0217 0.003 0.004 7 164 19140 0.0246 0.006 0.006 3 137 15141 0.0111 0.009 0.015 6 176 22142 0.0061 0.004 0.017 4 157 24143 0.0191 0.010 0.009 4 161 29144 0.0161 0.008 0.017 0 138 39145 0.0220 0.006 0.009 6 167 36146 0.0020 0.003 0.010 6 176 21147 0.0254 0.009 0.018 2 167 16148 0.0131 0.007 0.010 1 168 28149 0.0196 0.007 0.001 1 131 19150 0.0102 0.005 0.009 5 135 35151 0.0251 0.006 0.020 5 157 28152 0.0296 0.002 0.012 6 150 26153 0.0184 0.008 0.011 6 142 13154 0.0168 0.005 0.014 7 135 28155 0.0048 0.006 0.007 1 132 26156 0.0223 0.003 0.017 6 161 31157 0.0196 0.009 0.001 4 174 36158 0.0068 0.010 0.015 3 175 27159 0.0233 0.007 0.016 5 141 42160 0.0201 0.009 0.003 4 174 42______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 7-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________161 0.19 0.75 0.45 13.56 0.218 2.24 0.39 0.43 0.09162 0.21 0.37 0.97 16.56 0.721 2.96 0.02 0.43 0.10163 0.27 0.24 0.30 15.55 0.602 2.24 0.39 0.38 0.02164 0.18 0.63 0.7 08.38 0.691 2.83 0.35 0.47 0.04165 0.18 0.24 0.45 12.52 0.337 2.54 0.23 0.12 0.25166 0.23 0.10 0.21 6.25 0.857 0.80 0.83 0.46 0.25167 0.26 0.49 0.65 13.37 0.602 2.04 0.05 0.45 0.11168 0.25 0.49 0.85 12.46 0.906 2.46 0.19 0.26 0.05169 0.29 0.77 0.27 7.78 0.110 1.49 0.58 0.03 0.02170 0.18 0.40 0.78 16.70 0.537 0.22 0.58 0.43 0.10171 0.19 0.44 0.64 11.08 0.034 1.42 0.51 0.16 0.13172 0.20 0.75 0.54 8.30 0.926 2.89 0.21 0.10 0.20173 0.08 0.41 0.32 12.57 0.052 2.43 0.49 0.18 0.01174 0.07 0.49 0.27 15.46 0.749 1.19 0.73 0.08 0.15175 0.25 0.07 0.27 14.93 0.869 1.93 0.75 0.21 0.07176 0.30 0.59 0.56 8.71 0.735 0.79 0.39 0.24 0.11177 0.15 0.34 0.23 7.61 0.679 0.51 0.96 0.33 0.23178 0.05 0.78 0.73 16.09 0.047 2.23 0.83 0.41 0.03179 0.11 0.59 0.75 12.48 0.661 0.42 0.33 0.39 0.06180 0.12 0.05 0.54 14.09 0.366 2.83 0.76 0.44 0.17181 0.05 0.18 0.78 12.39 0.497 0.64 0.99 0.23 0.20182 0.13 0.48 0.93 5.14 0.880 1.55 0.36 0.42 0.10183 0.16 0.42 0.87 16.27 0.869 3.40 0.20 0.19 0.21184 0.11 0.66 0.86 11.14 0.788 2.33 0.81 0.45 0.11185 0.07 0.29 0.36 7.11 0.974 1.09 0.08 0.12 0.02186 0.14 0.74 0.86 15.01 0.764 2.46 0.80 0.12 0.12187 0.12 0.33 0.62 13.30 0.498 0.95 0.84 0.11 0.03188 0.26 0.09 0.30 12.80 0.503 0.93 0.04 0.27 0.07189 0.21 0.29 0.58 11.32 0.126 0.26 0.69 0.25 0.06190 0.09 0.80 0.93 13.34 0.694 1.68 0.18 0.49 0.22______________________________________ TABLE 7-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________161 -- 0.907 0.105 0.625 0.75 -- --162 -- 0.587 0.391 1.902 1.12 -- --163 1.594 -- 0.512 0.388 0.49 -- --164 0.508 -- 1.154 0.759 0.46 -- --165 1.338 -- 1.981 1.673 2.62 -- --166 1.761 -- 0.663 1.823 3.82 -- --167 0.476 -- 1.885 0.880 3.27 -- --168 1.154 -- 0.315 1.493 2.53 -- --169 1.447 0.255 -- 0.337 0.84 -- --170 0.041 1.529 -- 0.098 2.23 -- --171 0.597 0.681 -- 0.450 1.13 -- --172 1.775 0.354 -- 1.066 1.51 -- --173 0.262 1.210 -- 0.612 2.65 -- --174 1.757 1.947 -- 1.763 3.71 -- --175 1.909 0.205 1.307 1.158 3.80 -- --176 0.377 1.649 1.502 0.482 2.23 -- --177 0.853 0.995 0.970 0.450 0.70 -- --178 1.998 1.905 1.364 0.722 3.17 -- --179 0.493 0.040 1.344 1.935 1.58 -- --180 0.988 0.083 0.597 1.782 4.79 -- --181 0.188 -- -- -- -- 3.17 --182 0.712 -- -- -- -- 0.69 --183 0.283 -- -- -- -- 1.48 --184 0.562 -- -- -- -- 2.43 --185 1.198 -- -- -- -- 0.30 --186 1.887 -- -- -- -- 1.56 --187 -- 0.798 -- -- -- 2.98 --188 -- 1.187 -- -- -- 3.75 --189 -- 1.520 -- -- -- 3.12 --190 -- 1.477 -- -- -- 2.74 --______________________________________ TABLE 7-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________161 0.0220 0.006 0.009 3 154 18162 0.0238 0.004 0.003 4 156 34163 0.0208 0.002 0.010 3 159 29164 0.0230 0.003 0.009 4 142 33165 0.0107 0.006 0.015 2 155 47166 0.0088 0.010 0.005 3 178 44167 0.0123 0.008 0.007 2 162 32168 0.0162 0.007 0.006 5 137 33169 0.0157 0.007 0.009 3 178 24170 0.0062 0.006 0.005 0 165 27171 0.0273 0.002 0.017 5 175 19172 0.0294 0.008 0.014 2 135 37173 0.0078 0.003 0.013 4 173 26174 0.0170 0.010 0.019 6 143 50175 0.0218 0.003 0.011 5 171 40176 0.0029 0.004 0.013 2 161 44177 0.0156 0.003 0.005 3 140 36178 0.0098 0.003 0.010 3 137 57179 0.0103 0.002 0.018 2 177 35180 0.0120 0.002 0.013 2 165 37181 0.0255 0.008 0.014 5 154 7182 0.0009 0.009 0.017 2 145 12183 0.0223 0.002 0.009 1 142 10184 0.0260 0.001 0.015 2 173 12185 0.0067 0.008 0.004 2 165 18186 0.0192 0.004 0.010 6 145 23187 0.0289 0.010 0.013 3 142 18188 0.0008 0.006 0.017 6 134 23189 0.0196 0.004 0.011 2 147 22190 0.0209 0.008 0.019 2 135 19______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 8-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________191 0.27 0.33 0.81 10.22 0.553 1.33 0.31 0.39 0.14192 0.13 0.68 0.49 12.62 0.520 1.98 0.42 0.14 0.03193 0.05 0.18 0.64 12.12 0.945 1.44 0.36 0.13 0.09194 0.13 0.27 0.34 13.18 0.177 2.50 0.96 0.05 0.03195 0.04 0.41 0.65 13.48 0.033 1.27 0.56 0.05 0.18196 0.16 0.49 0.63 10.87 0.351 0.56 0.50 0.07 0.13197 0.30 0.37 0.56 16.37 0.473 3.09 0.60 0.01 0.10198 0.12 0.32 0.71 8.10 0.222 1.67 0.69 0.28 0.15199 0.15 0.58 0.92 16.48 0.429 2.40 0.13 0.32 0.01200 0.20 0.67 0.70 7.17 0.464 3.16 0.73 0.30 0.24201 0.23 0.44 0.70 16.85 0.149 3.36 0.86 0.37 0.09202 0.18 0.15 0.39 10.83 0.303 0.78 0.34 0.45 0.22203 0.16 0.46 0.44 13.07 0.771 1.49 0.98 0.47 0.13204 0.26 0.07 0.72 14.80 0.395 1.65 0.66 0.34 0.25205 0.29 0.80 0.69 7.58 0.508 0.75 0.69 0.23 0.18206 0.05 0.18 0.63 15.23 0.445 1.50 0.90 0.06 0.13207 0.08 0.42 0.40 9.31 0.031 1.73 0.65 0.23 0.05208 0.05 0.23 0.67 7.59 0.616 0.90 0.76 0.19 0.02209 0.04 0.66 0.52 14.30 0.038 1.78 0.57 0.33 0.02210 0.30 0.78 0.20 14.34 0.625 0.53 0.42 0.34 0.22211 0.20 0.08 0.80 11.98 0.714 1.52 0.12 0.36 0.13212 0.13 0.39 0.56 11.60 0.635 0.93 0.53 0.09 0.17213 0.20 0.41 0.98 17.71 0.248 1.56 0.99 0.18 0.07214 0.19 0.78 0.32 15.07 0.366 1.18 0.83 0.06 0.15215 0.08 0.22 0.84 7.95 0.323 2.51 0.39 0.12 0.01216 0.09 0.15 0.80 7.38 0.467 1.76 0.48 0.30 0.09217 0.05 0.44 0.49 11.21 0.633 1.71 0.48 0.27 0.11218 0.18 0.19 0.57 17.16 0.145 3.39 0.19 0.44 0.03219 0.15 0.05 0.91 10.31 0.857 1.41 0.95 0.24 0.18220 0.07 0.29 0.98 14.37 0.096 3.39 0.12 0.08 0.15______________________________________ TABLE 8-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________191 -- 0.724 -- -- -- 4.15 --192 -- 0.919 -- -- -- 4.15 --193 1.414 1.737 -- -- -- 1.99 --194 1.662 1.868 -- -- -- 4.10 --195 1.995 0.968 -- -- -- 4.86 --196 0.112 0.729 -- -- -- 1.15 --197 0.652 1.798 -- -- -- 4.10 --198 0.270 1.867 -- -- -- 0.94 --199 -- -- 1.997 -- -- 0.51 --200 -- -- 1.618 -- -- 4.42 --201 -- -- 0.590 -- -- 2.15 --202 -- -- 0.612 -- -- 0.32 --203 -- -- 0.376 -- -- 2.88 --204 -- -- 0.521 -- -- 1.81 --205 1.236 -- 1.723 -- -- 3.54 --206 0.913 -- 1.670 -- -- 2.48 --207 1.757 -- 0.032 -- -- 0.25 --208 0.433 -- 1.456 -- -- 3.23 --209 0.603 -- 0.634 -- -- 1.05 --210 0.952 -- 1.214 -- -- 2.47 --211 -- 1.529 0.895 -- -- 4.41 --212 -- 0.011 0.342 -- -- 1.20 --213 -- 0.565 0.231 -- -- 1.71 --214 -- 0.844 1.209 -- -- 2.64 --215 -- 0.545 1.976 -- -- 0.98 --216 -- 0.338 1.198 -- -- 2.99 --217 0.551 0.877 1.540 -- -- 3.18 --218 1.440 0.847 0.689 -- -- 0.69 --219 0.559 1.905 1.286 -- -- 2.00 --220 1.563 0.76 0.050 -- -- 1.47 --______________________________________ TABLE 8-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________191 0.0145 0.002 0.001 7 151 16192 0.0106 0.002 0.011 2 172 12193 0.0041 0.009 0.016 1 176 30194 0.0202 0.010 0.014 6 166 32195 0.0238 0.009 0.002 1 144 29196 0.0256 0.009 0.005 6 139 18197 0.0051 0.008 0.011 3 177 24198 0.0023 0.006 0.016 4 137 26199 0.0126 0.005 0.007 2 147 24200 0.0009 0.003 0.010 6 134 25201 0.0218 0.003 0.004 7 175 14202 0.0264 0.005 0.013 1 149 11203 0.0097 0.003 0.015 4 159 15204 0.0259 0.002 0.016 5 156 19205 0.0108 0.008 0.015 3 170 33206 0.0045 0.004 0.016 3 176 26207 0.0165 0.007 0.007 0 180 25208 0.0273 0.003 0.014 5 132 25209 0.0019 0.003 0.015 5 161 16210 0.0249 0.001 0.015 3 145 30211 0.0022 0.005 0.012 4 161 25212 0.0035 0.009 0.013 1 136 15213 0.0086 0.002 0.004 3 150 12214 0.0129 0.001 0.010 5 179 24215 0.0118 0.010 0.011 2 176 33216 0.0295 0.007 0.003 4 169 26217 0.0022 0.006 0.010 3 160 37218 0.0138 0.005 0.002 1 178 33219 0.0153 0.007 0.013 0 150 35220 0.0012 0.002 0.012 7 154 29______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 9-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________221 0.02 0.37 0.64 14.25 0.193 0.58 0.99 0.11 0.01222 0.25 0.18 0.97 14.38 0.985 2.32 0.46 0.27 0.23223 0.28 0.76 0.24 12.56 0.823 3.16 0.82 0.23 0.15224 0.06 0.03 0.70 13.02 0.518 2.47 0.41 0.14 0.21225 0.26 0.58 0.62 7.33 0.417 1.44 0.08 0.43 0.02226 0.26 0.35 0.30 12.90 0.374 2.84 0.16 0.03 0.01227 0.16 0.38 0.39 7.95 0.202 2.75 0.48 0.33 0.04228 0.06 0.14 0.34 16.35 0.737 2.34 0.38 0.27 0.04229 0.19 0.68 0.85 10.11 0.334 1.07 0.70 0.02 0.24230 0.22 0.32 0.98 6.50 0.315 3.32 0.29 0.22 0.23231 0.24 0.48 0.99 9.89 0.019 0.32 0.46 0.07 0.21232 0.22 0.65 0.35 11.64 0.776 3.05 0.55 0.22 0.14233 0.10 0.30 0.93 9.52 0.421 2.71 0.39 0.33 0.21234 0.26 0.48 1.00 14.56 0.306 0.47 0.34 0.10 0.16235 0.09 0.28 0.83 5.06 0.252 2.34 0.22 0.41 0.06236 0.25 0.36 0.69 11.45 0.104 1.20 0.86 0.21 0.12237 0.13 0.19 0.84 11.98 0.189 1.44 0.62 0.39 0.16238 0.25 0.04 0.76 11.14 0.848 0.89 0.81 0.40 0.05239 0.13 0.17 0.31 13.18 0.418 0.63 0.78 0.38 0.08240 0.15 0.06 0.97 9.52 0.730 1.79 0.38 0.01 0.23241 0.14 0.37 0.59 11.08 0.132 0.52 0.40 0.20 0.22242 0.17 0.56 0.66 9.08 0.438 1.24 0.23 0.13 0.12243 0.22 0.15 0.64 8.14 0.510 1.77 0.17 0.22 0.02244 0.22 0.54 0.79 5.96 0.671 1.54 0.56 0.12 0.24245 0.27 0.44 0.99 6.88 0.754 1.67 0.25 0.26 0.01246 0.05 0.51 0.31 8.74 0.595 1.62 0.07 0.06 0.03247 0.21 0.61 0.60 15.93 0.528 2.46 0.34 0.17 0.12248 0.15 0.23 0.96 13.52 0.402 2.07 0.42 0.28 0.14249 0.10 0.79 0.43 5.61 0.046 3.16 0.14 0.06 0.03250 0.15 0.24 0.89 16.22 0.789 0.26 0.81 0.40 0.13______________________________________ TABLE 9-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________221 0.118 1.041 0.597 -- -- 0.72 --222 0.915 0.451 1.641 -- -- 1.38 --223 -- -- -- 0.338 -- 2.68 --224 -- -- -- 0.103 -- 3.76 --225 -- -- -- 0.754 -- 1.52 --226 -- -- -- 0.945 -- 2.34 --227 -- -- -- 0.339 -- 0.58 --228 -- -- -- 1.617 -- 2.73 --229 0.410 -- -- 0.455 -- 3.20 --230 0.260 -- -- 0.507 -- 1.13 --231 0.398 -- -- 1.461 -- 0.59 --232 1.468 -- -- 1.955 -- 3.11 --233 0.153 -- -- 1.729 -- 3.26 --234 0.146 -- -- 0.403 -- 4.91 --235 -- 0.893 -- 0.643 -- 4.92 --236 -- 1.458 -- 0.163 -- 2.55 --237 -- 1.227 -- 1.607 -- 1.75 --238 -- 0.846 -- 0.642 -- 4.15 --239 -- 1.017 -- 1.958 -- 4.18 --240 -- 0.399 -- 0.226 -- 1.03 --241 -- -- 1.741 0.097 -- 3.51 --242 -- -- 1.531 0.248 -- 1.25 --243 -- -- 1.912 1.371 -- 0.65 --244 -- -- 0.554 0.116 -- 3.33 --245 -- -- 0.145 0.176 -- 1.31 --246 -- -- 0.350 0.219 -- 3.42 --247 -- 0.335 1.823 0.900 -- 1.63 --248 -- 0.570 0.249 1.891 -- 4.74 --249 -- 1.069 1.298 0.885 -- 4.80 --250 -- 0.499 0.648 0.540 -- 1.04 --______________________________________ TABLE 9-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________221 0.0120 0.010 0.006 2 168 20222 0.0271 0.003 0.018 6 143 32223 0.0277 0.007 0.009 3 159 9224 0.0230 0.006 0.014 3 168 13225 0.0086 0.004 0.019 4 147 18226 0.0089 0.009 0.002 2 174 19227 0.0194 0.004 0.009 3 177 10228 0.0204 0.008 0.016 2 134 26229 0.0067 0.004 0.002 2 173 18230 0.0034 0.009 0.011 0 170 17231 0.0054 0.008 0.012 4 180 28232 0.0227 0.010 0.020 1 179 36233 0.0212 0.002 0.013 1 170 29234 0.0099 0.003 0.016 7 132 18235 0.0147 0.005 0.018 6 142 24236 0.0153 0.008 0.014 4 177 19237 0.0220 0.006 0.012 0 165 33238 0.0147 0.009 0.017 4 160 25239 0.0184 0.005 0.018 4 138 29240 0.0283 0.004 0.020 3 153 13241 0.0096 0.004 0.010 2 157 26242 0.0171 0.001 0.015 0 178 19243 0.0012 0.006 0.011 1 169 37244 0.0164 0.004 0.007 5 157 15245 0.0286 0.003 0.016 6 170 9246 0.0176 0.010 0.009 5 136 14247 0.0082 0.010 0.018 1 133 33248 0.0253 0.002 0.004 1 139 31249 0.0195 0.002 0.012 2 155 34250 0.0158 0.008 0.018 4 161 25______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 10-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________251 0.12 0.76 0.21 17.18 0.976 1.07 0.81 0.49 0.03252 0.10 0.30 0.26 12.84 0.941 3.40 0.46 0.01 0.05253 0.04 0.26 0.90 13.98 0.512 3.38 0.57 0.34 0.15254 0.05 0.54 0.82 5.66 0.537 0.52 1.00 0.19 0.06255 0.21 0.61 0.25 11.51 0.332 2.45 0.09 0.19 0.09256 0.20 0.73 0.69 16.68 0.764 0.51 0.65 0.04 0.21257 0.25 0.40 0.41 12.40 0.647 2.29 0.43 0.12 0.25258 0.18 0.63 0.46 15.82 0.315 2.32 0.10 0.39 0.18259 0.07 0.15 0.33 12.23 0.620 1.77 0.15 0.49 0.07260 0.17 0.77 0.67 12.23 0.886 1.68 0.52 0.11 0.02261 0.30 0.03 0.95 13.70 0.948 1.55 0.57 0.39 0.09262 0.25 0.13 0.66 14.65 0.159 0.84 0.13 0.03 0.01263 0.12 0.57 0.85 6.34 0.834 0.64 0.02 0.42 0.22264 0.02 0.03 0.99 12.60 0.319 0.38 0.09 0.25 0.20265 0.18 0.73 0.95 11.85 0.441 2.87 0.65 0.17 0.03266 0.12 0.21 1.00 8.44 0.550 0.95 0.08 0.35 0.04267 0.23 0.67 0.21 6.70 0.468 0.67 0.19 0.22 0.05268 0.02 0.05 0.84 11.14 0.047 1.52 0.31 0.19 0.04269 0.04 0.55 0.78 6.58 0.613 2.94 0.30 0.19 0.08270 0.08 0.09 0.29 10.30 0.502 2.72 0.47 0.36 0.14271 0.09 0.10 0.82 7.14 0.545 0.32 0.66 0.15 0.17272 0.04 0.46 0.65 8.10 0.588 1.81 0.23 0.44 0.01273 0.02 0.26 0.86 10.97 0.960 3.38 0.98 0.20 0.11274 0.27 0.16 0.92 13.67 0.010 1.15 0.78 0.30 0.19275 0.16 0.79 0.67 13.99 0.551 1.18 0.94 0.19 0.09276 0.08 0.48 0.41 9.82 0.933 2.93 0.82 0.26 0.12277 0.13 0.27 0.39 5.54 0.494 0.92 0.73 0.21 0.13278 0.11 0.41 0.89 5.52 0.563 2.83 0.52 0.18 0.08279 0.27 0.79 0.97 7.62 0.973 3.21 0.53 0.34 0.05280 0.27 0.10 0.50 16.16 0.574 1.50 0.09 0.13 0.11______________________________________ TABLE 10-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________251 -- 1.532 1.968 1.534 -- 2.25 --252 -- 1.831 0.924 1.529 -- 0.42 --253 0.803 -- 1.189 1.203 -- 1.98 --254 1.794 -- 0.446 1.234 -- 3.76 --255 1.178 -- 1.347 0.282 -- 4.92 --256 0.669 -- 1.568 0.006 -- 2.30 --257 1.865 -- 1.787 0.110 -- 2.35 --258 1.510 -- 1.686 1.249 -- 4.24 --259 0.248 0.985 -- 1.109 -- 2.42 --260 0.747 1.654 -- 0.344 -- 3.26 --261 0.690 1.627 -- 0.621 -- 3.56 --262 0.733 0.594 -- 0.632 -- 2.61 --263 1.562 1.228 -- 0.042 -- 4.34 --264 1.829 0.192 -- 1.507 -- 0.81 --265 0.239 0.167 0.176 1.724 -- 0.82 --266 0.432 0.819 0.623 0.357 -- 1.19 --267 1.083 1.821 0.789 1.070 -- 1.12 --268 1.896 1.854 0.352 0.550 -- 2.25 --269 0.526 1.566 0.959 1.438 -- 1.33 --270 1.625 0.646 0.293 0.424 -- 4.80 --271 0.875 -- -- -- 4.92 4.72 --272 1.948 -- -- -- 1.30 2.68 --273 0.540 -- -- -- 1.21 0.25 --274 0.300 -- -- -- 3.89 1.47 --275 1.883 -- -- -- 1.33 0.73 --276 0.993 -- -- -- 4.81 2.10 --277 -- 1.883 -- -- 1.49 2.39 --278 -- 1.083 -- -- 2.60 3.16 --279 -- 1.692 -- -- 4.94 1.25 --280 -- 0.390 -- -- 0.53 3.06 --______________________________________ TABLE 10-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________251 0.0093 0.002 0.019 6 158 51252 0.0095 0.004 0.003 6 174 45253 0.0271 0.009 0.015 4 137 31254 0.0121 0.005 0.004 2 176 33255 0.0193 0.006 0.004 1 166 28256 0.0288 0.008 0.013 2 162 31257 0.0210 0.007 0.017 5 141 36258 0.0208 0.006 0.015 1 156 47259 0.0233 0.007 0.002 4 134 30260 0.0086 0.004 0.004 4 154 31261 0.0164 0.006 0.018 6 142 29262 0.0124 0.005 0.012 2 177 23263 0.0212 0.006 0.012 1 137 36264 0.0232 0.006 0.005 6 148 38265 0.0132 0.004 0.008 5 140 27266 0.0018 0.007 0.006 4 139 22267 0.0133 0.002 0.017 2 173 44268 0.0283 0.003 0.008 4 146 48269 0.0116 0.002 0.015 3 134 41270 0.0186 0.004 0.015 5 141 37271 0.0142 0.009 0.006 0 144 19272 0.0086 0.002 0.012 6 172 29273 0.0114 0.004 0.002 4 151 12274 0.0184 0.009 0.011 3 159 9275 0.0239 0.005 0.016 6 150 22276 0.0087 0.007 0.006 4 150 14277 0.0127 0.002 0.006 4 164 21278 0.0157 0.003 0.003 0 168 15279 0.0279 0.008 0.002 3 140 23280 0.0296 0.003 0.002 3 157 11______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 11-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________281 0.21 0.16 0.55 9.60 0.692 0.45 0.04 0.45 0.24282 0.04 0.07 1.00 11.83 0.171 1.18 0.69 0.47 0.03283 0.15 0.09 0.50 14.04 0.827 1.50 0.42 0.37 0.05284 0.05 0.48 0.93 7.76 0.514 0.83 0.03 0.06 0.24285 0.13 0.33 0.95 16.76 0.069 0.36 0.37 0.20 0.10286 0.20 0.30 0.84 13.00 0.319 1.12 0.28 0.46 0.06287 0.07 0.65 0.86 13.75 0.599 2.61 0.10 0.27 0.21288 0.13 0.07 0.49 10.48 0.256 2.63 0.64 0.29 0.02289 0.03 0.40 0.39 7.51 0.118 2.29 0.27 0.19 0.06290 0.17 0.72 0.43 15.69 0.023 1.04 0.79 0.38 0.04291 0.20 0.13 0.48 6.91 0.801 1.64 0.08 0.29 0.18292 0.08 0.05 0.80 17.97 0.794 0.25 0.43 0.32 0.17293 0.05 0.36 0.87 7.79 0.338 2.92 0.21 0.41 0.24294 0.07 0.15 0.95 13.30 0.768 2.54 0.73 0.47 0.10295 0.22 0.08 0.52 6.30 0.424 1.85 0.35 0.41 0.06296 0.18 0.40 0.65 17.17 0.631 0.29 0.39 0.17 0.22297 0.19 0.21 0.79 17.72 0.737 2.30 0.20 0.39 0.16298 0.20 0.55 0.42 12.37 0.565 2.34 0.59 0.25 0.10299 0.15 0.51 0.61 11.99 0.964 3.24 0.42 0.41 0.11300 0.16 0.74 0.43 14.49 0.270 2.76 0.04 0.31 0.03301 0.02 0.34 0.54 17.69 0.808 2.03 0.73 0.35 0.19302 0.13 0.75 0.43 6.51 0.925 0.51 0.88 0.21 0.18303 0.29 0.64 0.34 11.22 0.948 2.58 0.81 0.05 0.08304 0.15 0.30 0.56 16.62 0.212 1.09 0.84 0.27 0.22305 0.27 0.76 0.55 7.85 0.066 2.15 0.82 0.32 0.08306 0.15 0.73 0.98 8.57 0.328 0.23 0.59 0.10 0.08307 0.17 0.07 0.90 16.38 0.324 1.35 0.49 0.02 0.09308 0.15 0.21 1.00 16.52 0.413 3.37 0.79 0.02 0.17309 0.19 0.26 0.36 7.00 0.945 0.84 0.92 0.50 0.17310 0.09 0.10 0.43 11.53 0.243 3.12 0.70 0.40 0.06______________________________________ TABLE 11-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________281 -- 1.822 -- -- 0.53 0.58 --282 -- 0.712 -- -- 4.25 2.69 --283 0.574 0.683 -- -- 1.21 3.71 --284 1.971 1.393 -- -- 2.64 0.50 --285 0.951 0.559 -- -- 0.57 4.25 --286 0.147 1.851 -- -- 1.46 2.28 --287 1.251 1.941 -- -- 2.12 0.94 --288 1.925 0.495 -- -- 1.71 1.80 --289 -- -- 0.602 -- 4.25 1.71 --290 -- -- 0.709 -- 4.21 4.71 --291 -- -- 0.651 -- 3.13 0.35 --292 -- -- 1.113 -- 0.25 4.68 --293 -- -- 1.738 -- 1.96 2.45 --294 -- -- 0.233 -- 0.29 2.57 --295 1.277 -- 1.252 -- 4.05 4.16 --296 1.752 -- 1.482 -- 0.48 1.73 --297 1.867 -- 1.586 -- 0.75 1.61 --298 0.258 -- 1.229 -- 4.10 3.06 --299 1.616 -- 0.091 -- 4.93 0.46 --300 1.633 -- 1.842 -- 2.47 2.65 --301 -- 0.207 0.156 -- 0.70 4.02 --302 -- 0.750 0.712 -- 3.68 1.40 --303 -- 0.823 1.165 -- 0.99 1.22 --304 -- 1.106 1.196 -- 1.43 0.25 --305 -- 0.272 1.475 -- 1.84 4.92 --306 -- 0.980 1.667 -- 1.38 4.80 --307 0.959 1.913 1.452 -- 4.15 3.97 --308 0.239 1.730 1.484 -- 2.05 1.60 --309 0.234 0.142 0.479 -- 1.62 4.15 --310 0.586 0.789 1.078 -- 4.41 1.21 --______________________________________ TABLE 11-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________281 0.0006 0.008 0.018 3 149 19282 0.0259 0.009 0.019 6 142 19283 0.0106 0.004 0.010 7 139 17284 0.0248 0.009 0.018 4 167 39285 0.0186 0.006 0.010 4 131 19286 0.0028 0.010 0.012 6 156 28287 0.0166 0.006 0.012 1 172 36288 0.0106 0.008 0.015 5 156 29289 0.0243 0.008 0.010 1 134 17290 0.0235 0.009 0.012 1 137 10291 0.0029 0.007 0.017 3 140 13292 0.0171 0.007 0.004 7 172 15293 0.0018 0.009 0.009 4 160 20294 0.0268 0.003 0.017 4 133 16295 0.0125 0.004 0.016 3 167 34296 0.0286 0.007 0.014 1 141 38297 0.0256 0.002 0.015 6 133 31298 0.0133 0.009 0.009 6 169 18299 0.0016 0.009 0.019 6 179 21300 0.0008 0.009 0.005 6 139 41301 0.0209 0.008 0.002 4 177 15302 0.0271 0.009 0.016 2 171 17303 0.0147 0.006 0.015 0 174 22304 0.0232 0.003 0.007 0 164 28305 0.0032 0.005 0.015 4 143 26306 0.0239 0.004 0.009 1 139 33307 0.0065 0.006 0.005 2 180 40308 0.0204 0.006 0.018 1 143 33309 0.0012 0.006 0.008 7 131 14310 0.0183 0.002 0.018 0 172 31______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 12-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________311 0.10 0.74 0.29 14.89 0.132 1.34 0.43 0.12 0.14312 0.03 0.13 0.20 8.54 0.953 3.26 0.95 0.33 0.14313 0.10 0.47 0.84 16.34 0.552 1.73 0.14 0.45 0.03314 0.29 0.07 0.46 10.07 0.749 2.80 0.77 0.41 0.23315 0.24 0.76 0.95 7.19 0.887 2.62 0.23 0.11 0.24316 0.21 0.05 0.56 5.37 0.799 2.30 0.31 0.45 0.25317 0.14 0.18 0.76 15.68 0.326 2.95 0.87 0.40 0.22318 0.28 0.62 0.63 16.48 0.800 0.76 0.26 0.34 0.24319 0.14 0.06 0.44 12.09 0.065 3.41 0.30 0.44 0.02320 0.26 0.35 0.84 6.87 0.444 2.10 0.81 0.14 0.12321 0.15 0.56 0.52 11.65 0.278 2.91 0.67 0.09 0.16322 0.21 0.56 0.54 17.85 0.403 0.32 0.67 0.45 0.19323 0.23 0.24 0.36 10.32 0.656 0.43 0.67 0.16 0.08324 0.17 0.63 0.67 6.44 0.375 1.02 0.50 0.37 0.13325 0.29 0.05 0.52 17.17 0.401 1.58 0.51 0.27 0.07326 0.08 0.31 0.99 14.24 0.060 1.53 0.03 0.50 0.10327 0.23 0.12 0.74 15.10 0.691 2.00 0.37 0.50 0.06328 0.26 0.52 0.84 11.02 0.629 0.79 0.88 0.18 0.03329 0.26 0.22 0.77 12.93 0.212 0.64 0.41 0.44 0.21330 0.19 0.25 0.38 5.69 0.273 1.06 0.29 0.48 0.21331 0.28 0.09 0.35 13.06 0.640 1.43 0.84 0.45 0.09332 0.21 0.40 0.95 13.62 0.668 2.94 0.91 0.28 0.07333 0.21 0.67 0.85 11.63 0.684 3.36 0.85 0.36 0.09334 0.23 0.36 0.31 11.46 0.026 0.51 0.97 0.39 0.14335 0.09 0.54 0.81 17.53 0.522 0.44 0.13 0.03 0.04336 0.03 0.66 0.61 8.04 0.019 2.60 0.15 0.43 0.23337 0.28 0.62 0.37 6.98 0.339 1.51 0.85 0.03 0.20338 0.22 0.67 0.78 12.20 0.327 1.57 0.10 0.24 0.14339 0.10 0.29 0.90 8.67 0.824 2.27 0.71 0.47 0.03340 0.15 0.53 0.60 7.17 0.663 3.05 0.54 0.40 0.17______________________________________ TABLE 12-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________311 1.965 0.352 1.955 -- 2.43 3.98 --312 0.054 0.505 1.795 -- 4.50 2.06 --313 -- -- -- 1.693 0.23 4.31 --314 -- -- -- 1.243 0.81 0.29 --315 -- -- -- 0.129 3.07 3.63 --316 -- -- -- 0.034 1.47 3.98 --317 -- -- -- 0.616 4.78 0.50 --318 -- -- -- 1.532 2.57 2.03 --319 1.707 -- -- 0.482 1.32 2.97 --320 1.592 -- -- 1.121 2.61 2.54 --321 1.218 -- -- 1.121 3.243 4.73 --322 0.266 -- -- 0.167 2.46 3.99 --323 1.393 -- -- 1.917 1.86 4.32 --324 0.313 -- -- 1.054 3.06 2.51 --325 -- 0.257 -- 0.237 0.45 4.98 --326 -- 1.130 -- 1.148 2.86 3.76 --327 -- 0.652 -- 0.44 4.71 2.88 --328 -- 1.522 -- 0.823 2.82 1.52 --329 -- 1.408 -- 1.947 3.61 1.32 --330 -- 0.965 -- 0.483 3.85 3.85 --331 -- -- 1.949 1.098 2.78 1.15 --332 -- -- 1.906 1.463 1.98 1.98 --333 -- -- 0.919 0.267 3.09 0.85 --334 -- -- 1.668 0.168 0.56 1.74 --335 -- -- 1.800 0.808 3.05 3.71 --336 -- -- 0.987 1.876 0.29 1.33 --337 -- 0.199 0.960 1.110 1.18 1.10 --338 -- 1.373 1.368 1.138 4.86 2.12 --339 -- 0.261 0.847 1.601 0.87 3.55 --340 -- 0.544 1.096 0.207 2.89 4.68 --______________________________________ TABLE 12-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________311 0.0076 0.003 0.018 5 169 47312 0.0083 0.006 0.003 2 149 26313 0.0161 0.003 0.009 5 141 18314 0.0256 0.003 0.014 2 171 24315 0.0026 0.003 0.015 1 168 14316 0.0016 0.003 0.008 7 159 10317 0.0027 0.004 0.019 6 172 12318 0.0012 0.003 0.006 1 135 21319 0.0218 0.005 0.005 2 151 24320 0.0299 0.009 0.013 1 172 27321 0.0206 0.001 0.007 6 175 30322 0.0189 0.006 0.004 2 140 14323 0.0199 0.009 0.009 4 168 33324 0.0036 0.008 0.020 1 162 23325 0.0100 0.002 0.014 1 151 16326 0.0193 0.003 0.007 5 161 23327 0.0266 0.010 0.016 6 170 18328 0.0273 0.003 0.017 2 156 32329 0.0012 0.003 0.019 3 148 40330 0.0180 0.008 0.007 6 147 23331 0.0281 0.009 0.007 6 156 35332 0.0264 0.003 0.016 6 153 36333 0.0086 0.008 0.013 6 166 16334 0.0139 0.003 0.002 2 148 21335 0.0224 0.006 0.011 6 151 31336 0.0149 0.005 0.006 3 153 28337 0.0166 0.008 0.005 6 132 24338 0.0220 0.006 0.003 6 166 38339 0.0262 0.004 0.018 0 131 33340 0.0095 0.007 0.016 7 157 27______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 13-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________341 0.04 0.08 0.54 5.41 0.168 3.33 0.89 0.19 0.17342 0.30 0.77 0.60 8.00 0.184 2.60 0.64 0.02 0.22343 0.16 0.13 0.23 12.67 0.053 2.00 0.10 0.28 0.18344 0.14 0.37 0.92 17.37 0.596 0.93 0.11 0.41 0.24345 0.21 0.59 0.94 6.88 0.665 2.20 0.49 0.34 0.11346 0.03 0.66 0.54 5.17 0.092 0.30 0.11 0.22 0.01347 0.26 0.44 0.40 10.05 0.206 2.93 0.28 0.46 0.01348 0.30 0.60 0.39 6.34 0.342 2.94 0.34 0.49 0.20349 0.07 0.22 0.38 18.00 0.346 3.10 0.63 0.48 0.16350 0.13 0.34 0.63 16.75 0.539 2.88 0.98 0.10 0.11351 0.13 0.06 0.61 7.17 0.277 3.38 0.26 0.01 0.25352 0.03 0.04 0.20 6.57 0.387 2.43 0.76 0.13 0.17353 0.20 0.53 0.46 6.21 0.201 1.10 0.83 0.13 0.20354 0.18 0.62 0.86 17.01 0.057 2.16 0.81 0.42 0.17355 0.05 0.18 0.47 10.84 0.782 3.42 0.54 0.42 0.05356 0.06 0.64 0.35 11.51 0.730 2.69 0.85 0.07 0.03357 0.17 0.33 0.79 10.50 0.230 2.75 0.58 0.01 0.09358 0.02 0.28 0.43 5.52 0.600 2.99 0.05 0.16 0.05359 0.02 0.35 0.34 7.34 0.681 2.89 0.10 0.44 0.12360 0.11 0.43 0.42 14.27 0.844 2.01 0.59 0.30 0.02361 0.25 0.40 0.53 11.04 0.407 3.04 0.36 0.13 0.20362 0.09 0.12 0.52 14.75 0.187 2.10 0.21 0.09 0.12363 0.18 0.62 0.27 10.49 0.036 2.00 0.97 0.10 0.12364 0.03 0.23 0.85 9.05 0.284 2.18 0.04 0.10 0.15365 0.16 0.38 0.53 8.42 0.777 2.12 0.20 0.49 0.06366 0.11 0.54 0.37 12.80 0.344 2.88 0.79 0.44 0.03367 0.25 0.60 0.64 7.02 0.311 0.65 0.66 0.37 0.04368 0.25 0.02 0.42 15.15 0.529 1.50 0.16 0.21 0.17369 0.21 0.25 0.77 15.44 0.331 3.23 0.10 0.11 0.13370 0.07 0.77 0.76 12.22 0.544 0.32 0.31 0.23 0.13______________________________________ TABLE 13-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________341 -- 0.887 1.780 1.610 0.52 2.29 --342 -- 0.994 0.592 1.507 2.62 0.45 --343 0.348 -- 0.174 1.543 1.10 0.69 --344 1.622 -- 0.191 0.385 4.84 2.25 --345 1.781 -- 1.336 1.719 1.03 1.95 --346 1.478 -- 0.290 0.230 0.91 3.83 --347 0.402 -- 1.705 1.569 1.28 2.27 --348 0.205 -- 1.264 1.418 1.34 1.28 --349 1.566 1.846 -- 1.445 0.31 4.89 --350 0.166 0.064 -- 1.322 2.21 2.70 --351 1.679 1.062 -- 1.712 1.41 1.11 --352 0.775 0.508 -- 1.290 4.35 1.72 --353 1.108 1.097 -- 1.754 0.70 3.83 --354 0.365 0.493 -- 1.750 1.60 4.18 --355 0.197 0.371 0.494 1.962 3.91 4.41 --356 0.307 1.385 0.353 1.051 4.39 1.30 --357 0.354 0.230 0.404 1.689 2.27 3.65 --358 1.966 1.537 1.288 0.549 1.58 1.13 --359 0.872 1.011 1.703 1.293 1.49 4.89 --360 0.766 1.341 1.345 0.632 3.70 4.63 --361 1.274 -- -- -- -- -- 0.78362 0.074 -- -- -- -- -- 1.77363 1.826 -- -- -- -- -- 1.57364 1.239 -- -- -- -- -- 0.80365 0.962 -- -- -- -- -- 0.95366 0.660 -- -- -- -- -- 1.73367 -- 1.386 -- -- -- -- 1.95368 -- 0.581 -- -- -- -- 1.32369 -- 0.640 -- -- -- -- 1.31370 -- 0.253 -- -- -- -- 0.76______________________________________ TABLE 13-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________341 0.0268 0.009 0.015 4 170 44342 0.0284 0.003 0.020 2 149 37343 0.0094 0.005 0.019 6 146 30344 0.0242 0.006 0.008 7 138 26345 0.0236 0.005 0.014 5 180 51346 0.0028 0.007 0.014 6 148 20347 0.0164 0.004 0.004 1 169 40348 0.0144 0.002 0.002 4 173 27349 0.0075 0.005 0.002 5 161 43350 0.0200 0.002 0.013 1 161 26351 0.0026 0.009 0.003 5 177 40352 0.0098 0.003 0.005 4 136 26353 0.0222 0.005 0.008 5 164 42354 0.0199 0.004 0.019 2 166 26355 0.0128 0.008 0.004 2 170 30356 0.0109 0.006 0.010 4 176 32357 0.0239 0.005 0.003 6 165 26358 0.0029 0.005 0.011 5 162 46359 0.0019 0.004 0.009 0 146 50360 0.0018 0.004 0.006 0 146 45361 0.0121 0.010 0.016 3 137 24362 0.0282 0.005 0.008 5 173 9363 0.0151 0.002 0.008 6 133 26364 0.0279 0.004 0.012 4 168 20365 0.0018 0.010 0.008 3 156 18366 0.0213 0.008 0.002 3 175 13367 0.0223 0.002 0.020 6 153 22368 0.0293 0.005 0.020 0 168 17369 0.0077 0.009 0.018 6 146 16370 0.0122 0.005 0.011 3 167 11______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 14-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________371 0.08 0.27 0.26 16.45 0.018 2.17 0.65 0.02 0.01372 0.20 0.20 0.73 6.46 0.575 3.27 0.94 0.12 0.09373 0.08 0.02 0.45 6.10 0.063 3.07 0.05 0.46 0.08374 0.12 0.79 0.49 6.75 0.806 2.70 0.26 0.21 0.07375 0.11 0.43 0.71 12.68 0.144 3.22 0.92 0.03 0.02376 0.02 0.76 0.58 8.94 0.916 0.85 0.91 0.34 0.25377 0.23 0.07 0.78 12.81 0.463 3.28 0.53 0.31 0.12378 0.25 0.22 0.37 9.20 0.114 1.71 0.13 0.12 0.20379 0.19 0.28 0.41 8.84 0.204 0.54 0.03 0.41 0.07380 0.15 0.13 0.38 16.29 0.071 0.58 0.07 0.36 0.07381 0.21 0.80 0.54 16.16 0.047 2.22 0.09 0.41 0.03382 0.19 0.22 0.77 12.97 0.962 0.66 0.42 0.44 0.15383 0.03 0.21 0.94 17.69 0.675 0.67 0.40 0.16 0.16384 0.28 0.65 0.50 8.60 0.509 3.34 0.38 0.20 0.14385 0.02 0.63 0.55 16.04 0.796 3.15 0.18 0.25 0.04386 0.20 0.41 0.53 5.40 0.872 2.90 0.63 0.46 0.06387 0.07 0.24 0.31 6.94 0.081 2.01 0.58 0.03 0.18388 0.15 0.40 0.57 5.67 0.747 1.62 0.86 0.34 0.10389 0.24 0.75 0.79 5.97 0.219 2.81 0.81 0.33 0.14390 0.02 0.39 0.81 5.60 0.327 3.43 0.28 0.16 0.04391 0.15 0.74 0.92 15.52 0.905 1.25 0.08 0.01 0.23392 0.02 0.52 0.58 7.52 0.787 2.33 0.04 0.28 0.19393 0.15 0.75 0.87 5.49 0.322 1.19 1.00 0.40 0.11394 0.21 0.15 0.83 13.76 0.326 0.60 0.34 0.04 0.10395 0.29 0.55 0.77 10.90 0.159 3.33 0.84 0.11 0.09396 0.20 0.23 0.53 7.47 0.628 2.16 0.37 0.03 0.05397 0.04 0.27 0.79 8.05 0.094 1.60 0.75 0.22 0.19398 0.20 0.12 0.21 16.99 0.876 1.04 0.82 0.35 0.22399 0.19 0.05 0.66 12.52 0.822 3.27 0.91 0.33 0.22400 0.11 0.73 0.82 5.70 0.768 2.80 0.88 0.33 0.05______________________________________ TABLE 14-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________371 -- 0.091 -- -- -- -- 0.28372 -- 0.838 -- -- -- -- 1.35373 1.534 1.141 -- -- -- -- 0.98374 1.298 0.693 -- -- -- -- 0.69375 1.068 0.158 -- -- -- -- 1.96376 1.546 0.191 -- -- -- -- 0.91377 0.417 1.485 -- -- -- -- 1.75378 1.320 1.709 -- -- -- -- 0.58379 -- -- 1.218 -- -- -- 0.70380 -- -- 0.977 -- -- -- 0.92381 -- -- 0.050 -- -- -- 0.94382 -- -- 1.100 -- -- -- 0.46383 -- -- 0.792 -- -- -- 0.99384 -- -- 1.824 -- -- -- 1.34385 0.337 -- 1.856 -- -- -- 0.31386 0.783 -- 0.562 -- -- -- 1.20387 0.325 -- 1.566 -- -- -- 1.01388 0.636 -- 0.619 -- -- -- 0.37389 1.374 -- 1.370 -- -- -- 1.68390 1.231 -- 0.468 -- -- -- 1.01391 -- 1.846 0.600 -- -- -- 1.71392 -- 0.615 0.427 -- -- -- 0.75393 -- 0.388 0.627 -- -- -- 0.56394 -- 0.845 1.877 -- -- -- 1.72395 -- 1.652 0.850 -- -- -- 0.36396 -- 0.485 1.208 -- -- -- 1.57397 1.632 1.997 0.622 -- -- -- 1.45398 1.522 1.895 1.780 -- -- -- 1.51399 1.575 0.817 1.332 -- -- -- 1.47400 0.458 0.455 1.965 -- -- -- 1.02______________________________________ TABLE 14-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________371 0.0084 0.009 0.016 3 158 12372 0.0210 0.002 0.019 7 146 20373 0.0002 0.004 0.017 3 159 31374 0.0011 0.006 0.017 5 175 24375 0.0184 0.009 0.005 1 172 23376 0.0028 0.005 0.009 3 177 28377 0.0239 0.004 0.005 0 143 23378 0.0024 0.005 0.009 5 149 29379 0.0226 0.007 0.008 3 146 21380 0.0200 0.009 0.010 6 162 19381 0.0048 0.003 0.020 3 175 11382 0.0167 0.003 0.006 3 163 19383 0.0058 0.003 0.014 2 153 12384 0.0274 0.009 0.002 6 149 21385 0.0167 0.003 0.005 5 178 28386 0.0132 0.009 0.009 3 167 22387 0.0125 0.009 0.014 2 145 25388 0.0247 0.001 0.004 5 165 23389 0.0299 0.002 0.017 3 153 31390 0.0227 0.009 0.019 5 138 19391 0.0138 0.004 0.017 7 147 31392 0.0276 0.008 0.008 1 158 13393 0.0149 0.005 0.008 6 150 21394 0.0152 0.008 0.014 1 173 34395 0.0091 0.006 0.014 2 158 30396 0.0210 0.007 0.003 7 180 24397 0.0016 0.009 0.008 5 168 42398 0.0056 0.001 0.006 6 175 47399 0.0133 0.001 0.014 4 178 38400 0.0046 0.002 0.018 2 155 29______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 15-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________401 0.20 0.06 0.54 13.75 0.541 2.37 0.55 0.28 0.24402 0.13 0.27 0.52 8.69 0.489 1.47 0.25 0.10 0.06403 0.28 0.43 1.00 14.23 0.934 2.83 0.32 0.42 0.17404 0.17 0.44 0.65 15.29 0.219 0.94 0.09 0.20 0.18405 0.19 0.54 0.56 16.25 0.678 0.26 0.89 0.34 0.16406 0.15 0.21 0.57 8.35 0.646 1.85 0.10 0.27 0.21407 0.14 0.51 0.57 9.18 0.465 0.25 0.99 0.14 0.03408 0.11 0.52 0.82 16.50 0.964 3.17 0.46 0.13 0.08409 0.02 0.12 0.80 15.18 0.984 3.45 0.30 0.39 0.18410 0.25 0.73 0.75 9.38 0.845 2.16 0.85 0.37 0.07411 0.19 0.67 0.98 16.87 0.910 0.50 0.48 0.46 0.06412 0.20 0.59 0.53 15.88 0.010 2.85 0.99 0.10 0.23413 0.26 0.76 0.48 17.11 0.459 2.03 0.74 0.19 0.19414 0.01 0.66 0.29 12.13 0.611 0.83 0.07 0.16 0.25415 0.14 0.53 0.24 5.06 0.293 0.33 0.76 0.17 0.13416 0.02 0.27 0.98 13.47 0.848 1.67 0.22 0.38 0.16417 0.18 0.52 0.80 15.67 0.112 2.64 0.24 0.47 0.17418 0.29 0.37 0.36 16.09 0.914 2.72 0.67 0.37 0.01419 0.15 0.09 0.73 12.59 0.107 1.37 0.36 0.48 0.12420 0.29 0.33 0.98 15.88 0.997 1.30 0.61 0.23 0.09421 0.24 0.57 0.57 17.53 0.946 2.01 0.29 0.02 0.02422 0.08 0.67 0.58 15.17 0.280 1.30 0.23 0.03 0.21423 0.21 0.13 0.47 13.45 0.340 1.95 0.25 0.18 0.15424 0.14 0.38 0.51 16.45 0.446 3.35 0.19 0.37 0.04425 0.12 0.50 0.57 9.23 0.450 1.73 0.88 0.05 0.09426 0.10 0.76 0.53 15.66 0.189 3.11 0.69 0.11 0.12427 0.17 0.25 0.64 14.01 0.981 0.37 0.42 0.47 0.10428 0.15 0.41 0.38 15.19 0.190 1.23 0.92 0.32 0.24429 0.27 0.32 0.42 10.62 0.630 1.82 0.53 0.31 0.13430 0.06 0.65 0.22 11.12 0.646 3.26 0.58 0.12 0.10______________________________________ TABLE 15-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________401 0.848 1.455 1.334 -- -- -- 0.74402 1.406 0.521 1.130 -- -- -- 0.37403 -- -- -- 0.647 -- -- 1.41404 -- -- -- 1.144 -- -- 1.76405 -- -- -- 0.462 -- -- 0.23406 -- -- -- 0.253 -- -- 1.01407 -- -- -- 1.189 -- -- 1.12408 -- -- -- 1.944 -- -- 0.25409 0.479 -- -- 0.181 -- -- 0.82410 0.577 -- -- 1.580 -- -- 0.72411 1.898 -- -- 0.818 -- -- 1.47412 1.113 -- -- 1.575 -- -- 1.88413 1.885 -- -- 1.512 -- -- 0.73414 1.885 -- -- 0.287 -- -- 0.43415 -- 0.946 -- 0.587 -- -- 1.60416 -- 1.300 -- 1.065 -- -- 1.22417 -- 0.795 -- 0.427 -- -- 0.82418 -- 1.075 -- 0.310 -- -- 1.90419 -- 0.840 -- 1.414 -- -- 1.46420 -- 1.756 -- 0.398 -- -- 1.89421 -- -- 1.768 1.928 -- -- 0.22422 -- -- 1.066 1.688 -- -- 0.64423 -- -- 1.890 1.344 -- -- 1.95424 -- -- 1.902 0.556 -- -- 0.27425 -- -- 0.821 1.035 -- -- 0.71426 -- -- 0.277 1.420 -- -- 0.25427 -- 1.683 1.936 1.383 -- -- 1.31428 -- 0.951 0.485 1.593 -- -- 0.90429 -- 1.417 0.591 1.732 -- -- 1.40430 -- 0.760 1.950 0.497 -- -- 1.66______________________________________ TABLE 15-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________401 0.0047 0.003 0.006 7 134 45402 0.0234 0.007 0.014 5 142 38403 0.0112 0.003 0.008 4 132 16404 0.0230 0.003 0.015 1 133 17405 0.0238 0.002 0.013 4 146 18406 0.0240 0.002 0.007 3 149 11407 0.0035 0.002 0.005 1 171 16408 0.0169 0.009 0.003 4 139 20409 0.0151 0.005 0.008 4 130 18410 0.0074 0.009 0.007 2 173 22411 0.0195 0.008 0.016 2 145 26412 0.0163 0.003 0.012 6 173 27413 0.0078 0.008 0.003 2 136 40414 0.0039 0.007 0.012 7 162 22415 0.0149 0.002 0.010 1 177 26416 0.0208 0.007 0.002 2 160 30417 0.0018 0.002 0.005 0 139 14418 0.0127 0.002 0.004 2 166 18419 0.0190 0.003 0.018 4 169 22420 0.0153 0.008 0.003 0 151 25421 0.0121 0.004 0.015 4 139 42422 0.0043 0.006 0.011 3 161 27423 0.0018 0.002 0.009 4 146 36424 0.0149 0.004 0.005 2 169 24425 0.0240 0.003 0.014 3 161 26426 0.0085 0.004 0.005 6 172 26427 0.0089 0.003 0.004 2 131 52428 0.0201 0.002 0.007 4 141 34429 0.0222 0.005 0.002 5 179 37430 0.0257 0.005 0.014 6 173 32______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 16-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________431 0.19 0.08 0.86 8.06 0.572 3.36 0.41 0.15 0.10432 0.03 0.05 0.59 12.20 0.236 1.55 0.84 0.09 0.22433 0.26 0.44 0.51 8.61 0.483 2.27 0.72 0.33 0.05434 0.11 0.72 0.85 14.45 0.648 1.68 0.40 0.31 0.03435 0.11 0.38 0.71 8.35 0.574 2.56 0.70 0.20 0.14436 0.21 0.436 0.75 7.52 0.092 1.03 0.45 0.15 0.20437 0.22 0.44 0.43 16.23 0.519 3.12 0.97 0.34 0.18438 0.24 0.58 0.82 12.89 0.711 1.74 0.65 0.43 0.04439 0.08 0.38 0.60 8.48 0.502 1.28 0.28 0.35 0.10440 0.26 0.46 0.44 7.36 0.227 2.87 0.70 0.02 0.08441 0.16 0.72 0.99 13.74 0.713 1.00 0.28 0.09 0.06442 0.03 0.63 0.53 6.15 0.813 3.39 0.81 0.24 0.24443 0.10 0.46 0.54 8.40 0.850 2.87 0.17 0.13 0.10444 0.04 0.46 0.86 11.81 0.661 2.22 0.16 0.44 0.09445 0.23 0.50 0.99 14.35 0.090 0.90 0.62 0.33 0.15446 0.04 0.08 0.78 13.83 0.463 1.66 0.40 0.46 0.03447 0.17 0.23 0.90 14.57 0.618 2.32 0.82 0.27 0.02448 0.26 0.05 0.83 8.08 0.402 0.70 0.27 0.17 0.23449 0.27 0.57 0.83 11.65 0.143 1.18 1.00 0.31 0.23450 0.29 0.50 0.77 16.57 0.669 1.59 0.42 0.38 0.25451 0.29 0.10 0.52 7.82 0.828 1.38 0.82 0.29 0.23452 0.21 0.03 0.34 15.62 0.446 1.63 0.56 0.21 0.14453 0.29 0.54 0.52 5.58 0.371 1.86 0.46 0.30 0.06454 0.05 0.72 0.90 14.33 0.928 3.14 0.86 0.48 0.06455 0.18 0.45 0.57 13.87 0.463 3.28 0.12 0.19 0.24456 0.17 0.39 0.60 15.03 0.303 3.39 0.54 0.31 0.19457 0.15 0.79 0.84 9.06 0.777 1.26 0.46 0.28 0.22458 0.19 0.34 0.37 7.00 0.239 2.98 0.24 0.27 0.07459 0.26 0.11 0.27 6.71 0.517 1.40 0.70 0.19 0.05460 0.30 0.74 0.79 12.50 0.448 0.94 0.68 0.22 0.24______________________________________ TABLE 16-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________431 -- 0.639 1.211 0.524 -- -- 1.34432 -- 0.726 0.049 0.494 -- -- 1.06433 0.765 -- 1.131 1.079 -- -- 0.54434 1.520 -- 1.120 0.937 -- -- 1.25435 1.628 -- 1.707 0.763 -- -- 0.21436 1.741 -- 0.571 0.229 -- -- 0.75437 0.521 -- 0.369 0.994 -- -- 1.65438 0.678 -- 1.778 0.745 -- -- 1.73439 1.855 1.633 -- 0.136 -- -- 1.57440 1.728 1.576 -- 0.842 -- -- 1.78441 0.993 1.759 -- 0.519 -- -- 1.17442 0.294 1.893 -- 1.869 -- -- 1.25443 0.312 1.621 -- 0.568 -- -- 1.72444 0.709 0.615 -- 0.247 -- -- 1.40445 0.170 1.548 1.008 1.616 -- -- 0.86446 1.375 1.100 0.448 1.332 -- -- 0.75447 1.970 1.952 0.558 0.087 -- -- 1.64448 0.671 1.758 1.983 1.521 -- -- 1.45449 0.094 0.199 1.411 1.326 -- -- 0.77450 0.950 1.927 0.503 0.154 -- -- 0.22451 0.901 -- -- -- 4.33 -- 0.42452 0.608 -- -- -- 2.63 -- 1.03453 0.758 -- -- -- 1.95 -- 0.89454 0.010 -- -- -- 3.93 -- 1.50455 1.046 -- -- -- 0.49 -- 0.74456 1.534 -- -- -- 0.53 -- 1.06457 -- 0.062 -- -- 0.83 -- 0.33458 -- 1.419 -- -- 3.00 -- 1.86459 -- 1.131 -- -- 3.86 -- 0.85460 -- 1.846 -- -- 4.98 -- 1.52______________________________________ TABLE 16-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________431 0.0101 0.006 0.012 0 176 32432 0.0157 0.006 0.001 3 166 22433 0.0226 0.003 0.008 2 144 32434 0.0108 0.005 0.020 2 140 37435 0.0053 0.002 0.014 3 131 40436 0.0165 0.006 0.006 4 144 33437 0.0242 0.010 0.013 6 132 23438 0.0088 0.009 0.012 2 172 38439 0.0099 0.005 0.009 3 169 33440 0.0078 0.002 0.002 6 149 36441 0.0124 0.003 0.007 5 141 31442 0.0190 0.006 0.010 1 171 36443 0.0226 0.001 0.017 3 167 28444 0.0036 0.009 0.009 1 159 23445 0.0015 0.010 0.008 6 172 41446 0.0268 0.002 0.013 4 135 37447 0.0146 0.004 0.010 1 150 47448 0.0197 0.007 0.006 6 170 52449 0.0074 0.007 0.017 3 174 31450 0.0176 0.006 0.003 6 138 33451 0.0007 0.008 0.006 3 141 15452 0.0114 0.002 0.005 0 135 18453 0.0149 0.009 0.016 3 173 13454 0.0214 0.009 0.017 3 133 11455 0.0107 0.002 0.005 3 142 18456 0.0084 0.007 0.005 5 178 26457 0.0091 0.002 0.004 5 144 11458 0.0229 0.002 0.010 5 143 24459 0.0152 0.002 0.008 7 152 16460 0.0107 0.004 0.006 3 149 25______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 17-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________461 0.27 0.54 0.21 15.79 0.868 2.70 0.03 0.01 0.01462 0.13 0.55 0.80 7.85 0.113 1.18 0.06 0.24 0.15463 0.25 0.26 0.41 6.09 0.014 0.77 0.11 0.07 0.03464 0.30 0.30 0.93 14.73 0.397 2.59 0.51 0.18 0.19465 0.23 0.57 0.62 12.45 0.620 2.82 0.12 0.47 0.14466 0.14 0.54 0.55 9.95 0.021 2.57 0.27 0.13 0.18467 0.28 0.09 0.59 11.56 0.409 2.93 0.28 0.31 0.16468 0.01 0.24 0.60 15.14 0.641 3.35 0.99 0.43 0.03469 0.02 0.49 0.46 5.65 0.550 1.67 0.27 0.18 0.25470 0.25 0.72 0.44 13.48 0.473 0.64 0.90 0.20 0.04471 0.08 0.78 0.80 16.87 0.738 1.34 0.26 0.17 0.21472 0.18 0.56 0.61 13.71 0.186 3.25 0.66 0.26 0.24473 0.22 0.70 0.94 14.90 0.146 0.85 0.45 0.37 0.10474 0.29 0.68 0.86 5.26 0.960 1.91 0.94 0.44 0.21475 0.06 0.38 0.23 15.27 0.969 2.54 0.04 0.39 0.19476 0.21 0.47 0.55 10.34 0.013 0.58 0.98 0.13 0.11477 0.25 0.40 0.86 14.23 0.918 0.44 0.69 0.07 0.05478 0.13 0.05 0.62 11.72 0.517 3.18 0.94 0.14 0.10479 0.11 0.48 0.53 7.37 0.157 1.72 0.13 0.49 0.21480 0.26 0.38 0.84 5.44 0.166 0.43 0.52 0.07 0.11481 0.12 0.79 0.22 10.31 0.878 0.43 0.50 0.26 0.11482 0.07 0.41 0.55 13.34 0.637 2.82 0.39 0.26 0.18483 0.20 0.28 0.47 5.80 0.764 2.09 0.51 0.22 0.03484 0.04 0.29 0.28 11.76 0.117 1.05 0.72 0.06 0.24485 0.12 0.28 0.63 15.93 0.014 2.40 0.84 0.20 0.15486 0.09 0.55 0.60 9.73 0.294 0.71 0.23 0.31 0.09487 0.06 0.55 0.85 10.58 0.799 0.36 0.21 0.06 0.14488 0.27 0.57 0.85 9.79 0.363 0.78 0.58 0.10 0.02489 0.23 0.06 0.87 11.59 0.812 1.47 0.74 0.12 0.17490 0.05 0.09 0.39 7.64 0.499 0.22 0.49 0.04 0.07______________________________________ TABLE 17-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________461 -- 0.284 -- -- 0.84 -- 0.86462 -- 0.053 -- -- 2.56 -- 0.37463 1.029 0.881 -- -- 2.58 -- 1.59464 0.305 0.413 -- -- 3.94 -- 1.50465 0.086 1.331 -- -- 1.93 -- 0.68466 1.035 0.284 -- -- 0.30 -- 1.57467 1.834 1.978 -- -- 0.66 -- 0.27468 1.127 0.071 -- -- 2.23 -- 1.89469 -- -- 1.350 -- 1.78 -- 1.60470 -- -- 1.931 -- 0.92 -- 1.83471 -- -- 0.305 -- 3.74 -- 0.51472 -- -- 1.140 -- 2.19 -- 0.89473 -- -- 1.093 -- 2.73 -- 1.83474 -- -- 0.834 -- 4.53 -- 1.19475 1.094 -- 0.052 -- 1.99 -- 0.49476 1.700 -- 1.388 -- 3.94 -- 0.33477 0.871 -- 1.545 -- 2.39 -- 0.43478 0.274 -- 1.194 -- 3.81 -- 0.50479 0.595 -- 1.995 -- 4.95 -- 0.23480 0.478 -- 0.636 -- 2.62 -- 0.21481 -- 1.988 1.762 -- 0.90 -- 1.08482 - 1.189 0.072 -- 3.74 -- 1.62483 -- 0.864 0.220 -- 0.76 -- 0.65484 -- 1.683 0.881 -- 3.17 -- 1.45485 -- 0.327 0.723 -- 2.97 -- 1.04486 -- 0.457 1.435 -- 1.82 -- 1.83487 0.262 1.739 1.663 -- 3.70 -- 1.72488 0.936 0.868 0.105 -- 3.02 -- 0.41489 1.241 0.503 0.415 -- 1.41 -- 0.31490 0.844 1.313 1.270 -- 0.44 -- 0.22______________________________________ TABLE 17-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________461 0.0195 0.003 0.019 3 162 9462 0.0220 0.002 0.007 1 144 13463 0.0282 0.004 0.014 4 147 26464 0.0182 0.007 0.017 1 149 12465 0.0165 0.005 0.004 5 177 23466 0.0189 0.001 0.001 3 161 19467 0.0202 0.004 0.014 3 176 41468 0.0008 0.001 0.010 5 151 17469 0.0150 0.006 0.016 6 165 22470 0.0282 0.004 0.019 6 143 28471 0.0061 0.005 0.007 2 139 16472 0.0182 0.006 0.014 3 132 23473 0.0148 0.003 0.008 4 173 23474 0.0206 0.009 0.006 4 141 17475 0.0160 0.009 0.013 2 162 16476 0.0260 0.002 0.018 4 166 34477 0.0157 0.009 0.007 1 154 24478 0.0105 0.009 0.016 3 154 21479 0.0050 0.002 0.004 6 170 26480 0.0243 0.009 0.014 4 178 20481 0.0040 0.005 0.015 1 157 40482 0.0286 0.008 0.005 5 158 21483 0.0185 0.002 0.008 4 161 15484 0.0136 0.003 0.011 2 168 32485 0.0089 0.006 0.012 2 156 14486 0.0147 0.005 0.008 4 153 25487 0.0110 0.008 0.015 7 137 41488 0.0228 0.003 0.009 3 136 23489 0.0152 0.003 0.008 1 177 30490 0.0283 0.002 0.008 5 164 38______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 18-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________491 0.11 0.52 0.86 8.60 0.255 3.11 0.18 0.26 0.04492 0.22 0.44 0.96 12.39 0.406 1.30 0.62 0.45 0.05493 0.18 0.12 0.55 10.29 0.285 2.52 0.68 0.29 0.05494 0.10 0.59 0.71 6.80 0.746 2.96 0.68 0.19 0.24495 0.06 0.18 0.91 12.91 0.623 2.06 0.46 0.32 0.23496 0.03 0.70 0.61 6.71 0.744 0.94 0.84 0.36 0.09497 0.11 0.46 0.87 12.13 0.441 0.67 0.19 0.45 0.03498 0.23 0.12 0.39 14.14 0.553 0.73 0.30 0.04 0.13499 0.21 0.32 0.99 16.95 0.917 0.58 0.53 0.26 0.10500 0.15 0.16 0.59 12.09 0.371 1.32 0.72 0.07 0.15501 0.15 0.30 0.63 16.91 0.259 0.80 0.22 0.36 0.24502 0.16 0.21 0.58 16.24 0.900 3.39 0.34 0.06 0.08503 0.12 0.16 0.33 14.50 0.146 0.29 0.41 0.32 0.25504 0.29 0.79 0.51 9.34 0.813 2.54 0.78 0.09 0.21505 0.18 0.03 0.63 5.44 0.262 2.99 0.32 0.02 0.06506 0.18 0.10 0.94 13.51 0.811 2.75 0.80 0.02 0.11507 0.09 0.48 0.90 11.93 0.804 2.91 0.60 0.01 0.21508 0.01 0.64 0.39 17.95 0.566 1.27 0.05 0.17 0.18509 0.05 0.45 0.88 16.71 0.448 2.28 0.46 0.40 0.12510 0.14 0.58 0.23 5.75 0.275 0.41 0.70 0.15 0.22511 0.11 0.50 0.72 15.75 0.393 1.77 0.11 0.07 0.08512 0.04 0.48 0.22 11.89 0.129 2.46 0.97 0.30 0.15513 0.18 0.77 0.98 11.56 0.319 0.32 0.19 0.06 0.03514 0.19 0.08 0.88 6.15 0.302 3.04 0.05 0.47 0.03515 0.03 0.62 0.98 12.92 0.405 1.82 0.88 0.23 0.24516 0.08 0.70 0.38 10.44 0.978 1.11 0.09 0.25 0.14517 0.29 0.58 0.91 9.47 0.854 0.35 0.43 0.44 0.17518 0.04 0.53 0.45 7.77 0.857 2.25 0.29 0.23 0.04519 0.29 0.42 0.48 16.33 0.833 3.04 0.97 0.02 0.08520 0.13 0.50 0.46 13.55 0.621 0.51 0.84 0.49 0.14______________________________________ TABLE 18-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________491 1.420 0.968 1.336 -- 1.78 -- 0.74492 1.612 0.146 0.286 -- 4.58 -- 1.59493 -- -- -- 1.815 0.92 -- 0.66494 -- -- -- 0.475 1.99 -- 0.36495 -- -- -- 1.386 2.13 -- 1.29496 -- -- -- 0.238 3.04 -- 1.37497 -- -- -- 0.718 1.53 -- 0.29498 -- -- -- 1.476 1.57 -- 1.37499 1.378 -- -- 1.204 4.81 -- 0.69500 1.877 -- -- 1.555 0.83 -- 0.68501 1.073 -- -- 0.228 0.89 -- 1.03502 0.634 -- -- 0.848 1.70 -- 1.45503 1.207 -- -- 1.123 2.60 -- 0.74504 0.492 -- -- 0.742 2.77 -- 0.42505 -- 0.599 -- 0.337 1.40 -- 1.09506 -- 1.634 -- 0.592 4.87 -- 0.64507 -- 1.272 -- 1.196 2.87 -- 0.58508 -- 1.182 -- 0.802 4.15 -- 1.53509 -- 1.043 -- 0.094 0.75 -- 1.38510 -- 1.511 -- 1.722 3.86 -- 1.63511 -- -- 1.968 0.357 0.65 -- 1.08512 -- -- 1.807 0.712 4.83 -- 1.25513 -- -- 0.631 0.404 1.12 -- 1.83514 -- -- 1.130 1.153 0.84 -- 1.65515 -- -- 1.970 0.608 3.14 -- 0.41516 -- -- 0.844 0.450 2.44 -- 0.48517 -- 1.406 1.361 1.320 0.29 -- 1.60518 -- 1.987 0.280 1.939 3.22 -- 0.77519 -- 1.217 1.199 1.948 0.76 -- 1.29520 -- 0.797 1.829 1.029 4.15 -- 1.04______________________________________ TABLE 18-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________491 0.0123 0.002 0.006 3 173 39492 0.0071 0.003 0.008 7 157 21493 0.0079 0.003 0.012 2 146 24494 0.0245 0.006 0.004 5 165 15495 0.0233 0.003 0.010 3 143 16496 0.0113 0.005 0.008 0 157 8497 0.0017 0.009 0.014 5 136 16498 0.0032 0.008 0.005 2 156 25499 0.0261 0.002 0.008 1 147 30500 0.0208 0.003 0.009 4 135 38501 0.0119 0.009 0.005 7 148 25502 0.0095 0.009 0.003 4 164 19503 0.0092 0.003 0.018 6 160 25504 0.0205 0.002 0.020 4 165 18505 0.0240 0.005 0.014 4 131 15506 0.0143 0.010 0.016 5 136 26507 0.0018 0.007 0.014 6 133 24508 0.0262 0.007 0.013 1 149 25509 0.0082 0.010 0.002 1 162 23510 0.0021 0.004 0.006 1 150 38511 0.0033 0.003 0.012 6 140 32512 0.0220 0.004 0.017 1 136 30513 0.0080 0.006 0.018 4 164 17514 0.0020 0.002 0.002 5 153 23515 0.0135 0.001 0.014 7 131 34516 0.0224 0.001 0.003 1 175 22517 0.0097 0.006 0.013 5 163 39518 0.0295 0.003 0.013 3 148 41519 0.0026 0.002 0.019 1 157 39520 0.0285 0.005 0.008 1 143 41______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 19-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________521 0.09 0.67 0.26 16.70 0.548 2.34 0.72 0.07 0.04522 0.11 0.77 0.96 17.31 0.463 3.08 0.45 0.16 0.24523 0.17 0.31 0.41 13.03 0.187 2.15 0.85 0.42 0.09524 0.05 0.31 0.89 8.43 0.069 0.70 0.29 0.29 0.15525 0.15 0.26 0.27 14.18 0.923 3.06 0.07 0.18 0.02526 0.28 0.42 0.41 15.26 0.613 0.54 0.05 0.02 0.03527 0.24 0.67 0.78 16.12 0.466 2.46 0.05 0.44 0.25528 0.13 0.49 0.86 14.48 0.808 3.32 0.90 0.16 0.17529 0.20 0.53 0.92 14.76 0.484 0.91 0.47 0.30 0.22530 0.10 0.27 0.41 14.93 0.335 1.34 0.08 0.06 0.01531 0.22 0.75 0.81 12.70 0.682 0.72 0.05 0.10 0.10532 0.08 0.68 0.39 12.54 0.873 3.49 0.72 0.33 0.09533 0.08 0.31 0.22 5.73 0.240 0.83 0.44 0.17 0.17534 0.29 0.69 0.55 16.06 0.103 0.43 0.53 0.29 0.07535 0.25 0.13 0.87 9.12 0.824 1.81 0.83 0.12 0.11536 0.20 0.46 0.25 15.12 0.223 2.73 0.20 0.30 0.13537 0.08 0.36 0.94 12.48 0.146 1.04 0.93 0.03 0.21538 0.28 0.12 0.83 12.06 0.418 1.13 0.41 0.45 0.20539 0.04 0.77 0.98 11.84 0.884 2.45 0.43 0.25 0.16530 0.03 0.22 0.84 15.87 0.871 1.14 0.84 0.09 0.19541 0.06 0.31 0.71 15.93 0.728 1.65 0.98 0.13 0.24542 0.22 0.52 0.84 16.03 0.282 1.77 0.70 0.05 0.16543 0.18 0.32 0.31 7.84 0.873 0.98 0.33 0.25 0.14544 0.03 0.37 0.58 14.93 0.328 0.32 0.18 0.41 0.14545 0.01 0.15 0.32 9.32 0.984 2.62 0.10 0.22 0.01546 0.09 0.71 0.60 15.01 0.200 0.74 0.93 0.31 0.19547 0.07 0.74 0.49 16.69 0.784 0.70 0.02 0.37 0.15548 0.04 0.52 0.26 12.21 0.582 1.96 0.18 0.31 0.22549 0.24 0.67 0.57 12.50 0.928 0.69 0.75 0.06 0.12550 0.20 0.70 0.90 8.91 0.161 2.94 0.09 0.02 0.17______________________________________ TABLE 19-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________521 -- 1.365 0.836 0.848 2.98 -- 0.67522 -- 1.611 0.870 0.066 3.68 -- 0.75523 1.828 -- 0.653 1.394 3.12 -- 1.91524 0.234 -- 1.815 1.474 0.44 -- 1.14525 1.435 -- 0.036 1.973 4.44 -- 1.74526 0.149 -- 0.984 1.575 4.77 -- 1.64527 0.015 -- 1.338 0.941 0.62 -- 0.50528 0.706 -- 1.753 0.750 0.81 -- 1.65529 0.888 1.824 -- 1.679 4.58 -- 0.31530 1.249 0.694 -- 0.401 1.52 -- 0.67531 0.462 1.294 -- 0.588 2.86 -- 1.52532 0.187 1.268 -- 1.879 2.94 -- 1.69533 0.075 1.335 -- 1.002 3.49 -- 0.89534 0.827 0.153 -- 0.607 1.28 -- 0.60535 0.120 0.372 1.380 1.348 2.68 -- 1.44536 0.595 0.675 0.614 0.903 2.09 -- 1.29537 0.960 1.725 0.976 0.955 3.62 -- 0.79538 1.869 0.194 0.113 1.146 1.54 -- 0.51539 1.982 1.779 0.737 0.198 2.41 -- 1.98530 2.000 0.144 1.500 1.749 2.97 -- 1.31541 0.566 -- -- -- -- 2.44 0.88542 0.386 -- -- -- -- 4.35 1.31543 1.093 -- -- -- -- 2.05 0.50544 1.369 -- -- -- -- 2.00 0.86545 1.909 -- -- -- -- 3.39 1.19546 1.372 -- -- -- -- 3.02 1.18547 -- 0.694 -- -- -- 4.87 1.45548 -- 1.400 -- -- -- 3.45 0.82549 -- 0.936 -- -- -- 0.29 0.76550 -- 0.968 -- -- -- 1.88 1.02______________________________________ TABLE 19-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________521 0.0127 0.001 0.016 3 134 34522 0.0249 0.008 0.001 4 157 26523 0.0009 0.009 0.008 0 142 38524 0.0100 0.009 0.015 1 163 36525 0.0025 0.005 0.018 6 151 39526 0.0036 0.006 0.005 2 158 31527 0.0229 0.005 0.010 4 161 25528 0.0112 0.005 0.013 1 138 35529 0.0084 0.005 0.018 1 166 46530 0.0243 0.003 0.014 3 175 30531 0.0091 0.003 0.016 1 165 31532 0.0029 0.002 0.002 1 165 37533 0.0011 0.005 0.017 3 178 26534 0.0282 0.004 0.010 1 131 19535 0.0048 0.008 0.006 2 153 34536 0.0004 0.005 0.012 4 170 34537 0.0252 0.004 0.005 7 162 45538 0.0297 0.004 0.002 1 154 38539 0.0090 0.006 0.009 4 175 43530 0.0178 0.005 0.003 4 154 54541 0.0063 0.004 0.001 3 167 11542 0.0146 0.006 0.009 3 142 16543 0.0225 0.001 0.015 4 157 20544 0.0106 0.005 0.014 3 140 20545 0.0037 0.003 0.015 5 169 26546 0.0266 0.003 0.013 6 146 25547 0.0297 0.008 0.015 4 148 17548 0.0233 0.002 0.017 6 180 21549 0.0022 0.007 0.008 2 168 13550 0.0067 0.008 0.003 4 165 21______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 20-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________551 0.16 0.47 0.70 5.73 0.609 1.57 0.50 0.36 0.21552 0.06 0.25 0.67 14.06 0.626 1.03 0.35 0.26 0.08553 0.01 0.68 0.65 12.02 0.032 0.72 0.45 0.13 0.21554 0.25 0.48 0.93 10.68 0.669 3.45 0.65 0.14 0.22555 0.15 0.67 0.56 7.65 0.862 2.01 0.29 0.46 0.07556 0.10 0.36 0.22 7.62 0.968 0.89 0.68 0.26 0.18557 0.19 0.59 0.98 8.28 0.317 2.81 0.21 0.45 0.05558 0.24 0.06 0.71 14.01 0.235 2.28 0.16 0.46 0.23559 0.05 0.58 0.86 16.07 0.052 2.00 0.37 0.43 0.21560 0.15 0.08 0.92 5.99 0.622 1.56 0.22 0.32 0.06561 0.21 0.39 0.35 14.08 0.772 0.31 0.99 0.03 0.11562 0.17 0.21 0.62 12.26 0.843 2.71 0.58 0.21 0.07563 0.15 0.18 0.40 11.34 0.171 1.60 0.28 0.29 0.03564 0.22 0.58 0.76 15.69 0.086 1.39 0.43 0.44 0.07565 0.06 0.10 0.77 16.73 0.427 3.20 0.87 0.34 0.15566 0.06 0.56 0.29 12.23 0.028 3.16 0.45 0.39 0.23567 0.30 0.28 0.40 6.64 0.228 2.42 0.48 0.02 0.14568 0.16 0.68 0.95 17.20 0.850 2.03 0.81 0.13 0.10569 0.04 0.48 0.63 15.87 0.745 1.48 0.29 0.15 0.17570 0.16 0.69 0.49 6.96 0.736 0.20 0.22 0.49 0.09571 0.06 0.05 0.41 14.39 0.179 2.68 0.47 0.10 0.17572 0.26 0.75 0.66 16.58 0.888 3.35 0.36 0.35 0.13573 0.13 0.73 0.71 11.34 0.224 1.72 0.73 0.20 0.18574 0.21 0.62 0.42 16.10 0.006 0.53 0.42 0.04 0.03575 0.16 0.31 0.48 15.72 0.075 0.90 0.27 0.06 0.12576 0.23 0.05 0.72 7.87 0.252 2.23 0.10 0.39 0.06577 0.06 0.10 0.24 16.61 0.389 0.74 0.74 0.24 0.04578 0.06 0.35 0.91 7.32 0.818 2.47 0.55 0.26 0.16579 0.03 0.65 0.57 10.25 0.876 1.92 0.85 0.37 0.23580 0.21 0.11 0.72 10.38 0.409 1.88 0.99 0.48 0.12______________________________________ TABLE 20-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________551 -- 1.163 -- -- -- 2.58 1.27552 -- 0.203 -- -- -- 4.02 0.33553 0.758 1.720 -- -- -- 0.52 0.57554 1.744 1.419 -- -- -- 1.01 1.73555 0.717 1.982 -- -- -- 2.27 0.83556 1.334 0.065 -- -- -- 1.11 0.23557 0.274 1.342 -- -- -- 3.95 1.47558 0.186 1.479 -- -- -- 2.80 0.65559 -- -- 0.968 -- -- 1.65 1.95560 -- -- 0.609 -- -- 4.54 1.50561 -- -- 0.498 -- -- 3.47 0.78562 -- -- 1.290 -- -- 4.81 0.42563 -- -- 1.690 -- -- 3.06 1.92564 -- -- 1.357 -- -- 4.57 1.37565 1.501 -- 1.926 -- -- 1.35 1.18566 1.464 -- 0.140 -- -- 4.65 1.97567 1.448 -- 1.617 -- -- 4.04 1.62568 0.145 -- 0.046 -- -- 1.21 1.67569 0.196 -- 1.116 -- -- 4.89 0.89570 0.293 -- 1.467 -- -- 4.74 0.80571 -- 1.772 0.787 -- -- 4.76 0.21572 -- 0.587 1.743 -- -- 1.72 1.49573 -- 0.327 1.014 -- -- 4.49 1.70574 -- 1.695 1.273 -- -- 0.28 1.41575 -- 0.357 0.190 -- -- 0.28 0.34576 -- 1.963 0.423 -- -- 3.72 1.78577 0.748 0.217 1.659 -- -- 4.99 1.84578 1.401 0.776 1.577 -- -- 3.29 1.12579 0.159 1.287 1.805 -- -- 2.67 0.22580 0.669 1.461 1.073 -- -- 4.73 0.67______________________________________ TABLE 20-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________551 0.0015 0.008 0.008 5 148 17552 0.0267 0.004 0.002 6 172 8553 0.0026 0.006 0.019 6 163 32554 0.0141 0.007 0.008 4 174 29555 0.0117 0.005 0.015 3 133 27556 0.0051 0.003 0.016 1 143 23557 0.0043 0.010 0.009 5 131 18558 0.0048 0.009 0.020 2 175 22559 0.0162 0.009 0.015 6 177 18560 0.0189 0.003 0.003 4 167 19561 0.0078 0.004 0.008 7 145 9562 0.0080 0.006 0.018 2 141 16563 0.0296 0.006 0.010 2 131 23564 0.0226 0.009 0.019 7 144 20565 0.0272 0.003 0.014 4 131 35566 0.0237 0.005 0.002 3 147 17567 0.0067 0.005 0.017 6 144 35568 0.0019 0.006 0.017 2 174 8569 0.0037 0.006 0.020 3 165 22570 0.0074 0.004 0.002 2 144 25571 0.0084 0.002 0.018 1 141 29572 0.0012 0.005 0.007 1 132 25573 0.0263 0.005 0.014 6 145 24574 0.0189 0.001 0.017 7 157 28575 0.0038 0.006 0.012 6 148 18576 0.0061 0.009 0.016 3 168 31577 0.0210 0.008 0.007 4 171 29578 0.0134 0.006 0.019 6 136 36579 0.0085 0.003 0.010 6 138 39580 0.0162 0.009 0.008 2 157 33______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 21-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________581 0.26 0.15 0.42 5.47 0.232 1.78 0.31 0.04 0.01582 0.29 0.27 0.73 13.00 0.693 1.08 0.61 0.17 0.24583 0.09 0.31 0.32 17.77 0.126 0.89 0.75 0.31 0.15584 0.06 0.56 0.27 11.16 0.864 2.33 0.09 0.39 0.19585 0.29 0.49 0.83 10.43 0.250 3.19 0.90 0.07 0.08586 0.02 0.37 0.69 7.15 0.614 1.28 0.10 0.25 0.15587 0.06 0.06 0.51 12.08 0.794 1.05 0.95 0.13 0.22588 0.07 0.60 0.94 16.45 0.616 0.23 0.82 0.34 0.15589 0.16 0.71 0.68 11.92 0.437 3.29 0.07 0.34 0.02590 0.13 0.26 0.78 15.66 0.573 3.08 0.49 0.02 0.01591 0.22 0.66 0.32 6.08 0.875 2.37 0.45 0.06 0.10592 0.10 0.64 0.77 7.16 0.181 2.24 0.76 0.11 0.25593 0.29 0.44 0.38 16.55 0.306 0.50 0.28 0.36 0.17594 0.18 0.73 0.63 6.24 0.100 3.23 0.82 0.46 0.07595 0.29 0.20 0.59 6.57 0.893 1.61 0.74 0.10 0.14596 0.28 0.66 0.92 8.93 0.029 1.71 0.86 0.43 0.24597 0.26 0.45 0.31 11.18 0.341 1.35 0.53 0.37 0.07598 0.17 0.21 0.20 17.68 0.164 3.28 0.08 0.10 0.08599 0.26 0.19 0.49 13.31 0.331 2.03 0.34 0.27 0.23600 0.19 0.29 0.22 15.47 0.684 1.99 0.16 0.06 0.24601 0.06 0.75 0.48 90.00 0.559 2.61 0.35 0.38 0.07602 0.25 0.27 0.73 11.25 0.289 1.71 0.27 0.41 0.04603 0.14 0.69 0.84 13.59 0.208 0.40 0.25 0.31 0.23604 0.26 0.69 0.67 7.38 0.652 3.06 0.12 0.24 0.13605 0.27 0.55 0.90 10.01 0.958 0.96 0.71 0.39 0.17606 0.13 0.52 1.00 12.72 0.456 3.36 0.86 0.15 0.07607 0.07 0.48 0.42 13.60 0.998 1.58 0.93 0.22 0.16608 0.20 0.69 0.66 16.91 0.910 1.62 0.25 0.23 0.04609 0.03 0.63 0.76 14.01 0.526 1.29 0.13 0.14 0.02610 0.24 0.57 0.20 9.22 0.685 3.35 0.90 0.33 0.18______________________________________ TABLE 21-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________581 1.622 1.938 0.020 -- -- 1.45 0.35582 0.687 1.423 1.327 -- -- 1.73 1.69583 -- -- -- 1.260 -- 4.65 1.65584 -- -- -- 1.256 -- 2.37 0.89585 -- -- -- 1.984 -- 1.20 1.78586 -- -- -- 0.122 -- 2.79 0.43587 -- -- -- 1.345 -- 3.91 1.94588 -- -- -- 1.320 -- 1.47 0.65589 0.546 -- -- 0.716 -- 4.16 1.60590 0.644 -- -- 0.228 -- 1.69 1.86591 1.916 -- -- 1.515 -- 2.86 0.20592 1.005 -- -- 0.252 -- 2.05 0.83593 1.589 -- -- 0.094 -- 3.26 0.77594 0.356 -- -- 1.712 -- 3.31 0.59595 -- 1.529 -- 1.801 -- 3.84 0.92596 -- 1.422 -- 0.017 -- 4.03 1.45597 -- 1.391 -- 0.041 -- 3.13 1.90598 -- 1.101 -- 1.535 -- 0.31 1.97599 -- 1.223 -- 1.181 -- 2.05 1.38600 -- 1.421 -- 0.639 -- 2.66 0.69601 -- -- 1.739 1.583 -- 1.42 1.44602 -- -- 0.303 1.700 -- 2.36 1.54603 -- -- 1.329 0.655 -- 2.26 0.67604 -- -- 0.498 0.114 -- 2.76 0.37605 -- -- 1.481 0.756 -- 3.05 1.21606 -- -- 0.943 1.241 -- 2.30 1.10607 -- 0.662 0.552 1.241 -- 4.57 1.55608 -- 0.723 0.986 0.437 -- 4.28 1.36609 -- 0.908 1.908 1.479 -- 2.98 1.14610 -- 1.901 0.016 1.085 -- 2.39 1.50______________________________________ TABLE 21-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________581 0.0168 0.002 0.017 0 170 35582 0.0054 0.001 0.016 3 154 38583 0.0068 0.002 0.002 6 138 15584 0.0015 0.006 0.019 4 149 19585 0.0291 0.009 0.017 7 164 26586 0.0103 0.004 0.001 2 163 9587 0.0143 0.003 0.017 0 172 18588 0.0221 0.004 0.013 3 169 16589 0.0280 0.007 0.005 5 156 22590 0.0276 0.005 0.010 7 138 19591 0.0161 0.001 0.006 6 141 33592 0.0032 0.008 0.017 5 142 21593 0.0289 0.010 0.012 6 171 25594 0.0283 0.010 0.007 6 154 30595 0.0268 0.007 0.017 2 169 32596 0.0193 0.003 0.003 7 144 19597 0.0009 0.008 0.017 3 157 17598 0.0265 0.009 0.018 6 160 28599 0.0167 0.010 0.013 5 157 27600 0.0257 0.009 0.018 2 149 29601 0.0193 0.005 0.010 6 140 34602 0.0224 0.006 0.006 5 158 25603 0.0152 0.001 0.012 6 179 27604 0.0076 0.007 0.015 0 132 10605 0.0247 0.008 0.003 4 170 27606 0.0015 0.003 0.020 2 170 25607 0.0229 0.009 0.015 0 135 29608 0.0095 0.010 0.014 2 143 27609 0.0159 0.010 0.003 4 172 38610 0.0075 0.007 0.010 4 173 33______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 22-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________611 0.06 0.75 0.85 6.96 0.221 0.67 0.93 0.24 0.13612 0.16 0.68 0.97 5.05 0.465 0.93 0.06 0.28 0.07613 0.20 0.61 0.85 14.50 0.765 0.34 0.09 0.13 0.20614 0.15 0.40 0.74 13.63 0.956 3.29 0.87 0.43 0.24615 0.24 0.73 0.92 6.76 0.871 0.98 0.26 0.38 0.03616 0.27 0.28 0.85 11.21 0.341 1.10 0.06 0.14 0.12617 0.07 0.10 0.80 11.88 0.697 1.47 0.61 0.36 0.01618 0.15 0.43 0.23 6.61 0.290 3.21 0.27 0.23 0.13619 0.18 0.40 0.63 12.80 0.940 2.46 0.84 0.15 0.20620 0.11 0.25 0.26 15.43 0.505 0.37 0.22 0.30 0.18621 0.19 0.25 0.58 5.71 0.799 1.30 0.18 0.10 0.04622 0.08 0.26 0.26 7.56 0.172 1.43 0.09 0.20 0.09623 0.17 0.16 0.78 5.84 0.449 0.22 0.76 0.29 0.06624 0.11 0.61 0.41 11.42 0.473 0.43 0.06 0.27 0.14625 0.16 0.69 0.60 9.18 0.081 1.51 0.79 0.07 0.06626 0.25 0.27 0.43 9.97 0.104 2.91 0.33 0.11 0.13627 0.21 0.79 0.58 11.66 0.378 0.82 0.96 0.29 0.20628 0.13 0.57 0.50 12.18 0.247 1.29 0.58 0.30 0.23629 0.10 0.63 0.47 15.79 0.038 2.10 0.96 0.05 0.17630 0.22 0.08 0.34 7.35 0.583 2.72 .0.98 0.44 0.24631 0.02 0.34 0.81 17.28 0.726 0.96 0.48 0.17 0.14632 0.30 0.50 0.92 10.90 0.297 2.86 0.26 0.13 0.08633 0.01 0.45 0.95 5.68 0.645 1.34 0.67 0.50 0.15634 0.27 0.06 0.38 5.99 0.101 2.42 0.08 0.45 0.17635 0.16 0.75 0.27 9.63 0.992 0.62 0.77 0.15 0.12636 0.05 0.43 0.88 7.89 0.657 0.30 0.12 0.26 0.19637 0.05 0.56 0.89 11.77 0.438 0.98 0.44 0.20 0.22638 0.12 0.23 0.96 6.15 0.172 2.10 0.58 0.15 0.18639 0.20 0.07 0.97 8.23 0.674 3.08 0.36 0.25 0.02640 0.10 0.74 0.38 9.49 0.309 3.44 0.15 0.20 0.07______________________________________ TABLE 22-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________611 -- 1.381 0.967 0.900 -- 1.64 0.34612 -- 0.010 0.436 1.594 -- 2.40 1.87613 1.738 -- 1.064 0.821 -- 3.80 1.28614 0.015 -- 0.569 1.286 -- 2.72 1.88615 0.557 -- 0.610 1.656 -- 0.78 0.70616 0.062 -- 1.833 1.572 -- 1.89 1.89617 1.170 -- 0.944 0.755 -- 0.64 0.72618 1.575 -- 0.590 1.822 -- 3.24 1.33619 1.956 0.861 -- 1.500 -- 1.90 0.79620 0.979 0.857 -- 1.441 -- 0.52 0.56621 0.312 1.024 -- 1.287 -- 3.11 0.36622 1.631 1.064 -- 0.743 -- 4.11 0.79623 0.603 0.650 -- 1.475 -- 2.74 0.66624 0.890 1.443 -- 1.153 -- 2.98 1.46625 0.186 0.115 0.895 0.440 -- 1.67 0.21626 0.151 0.336 0.101 1.003 -- 2.78 1.11627 0.464 1.771 0.887 0.537 -- 0.78 1.17628 1.782 0.127 1.952 0.700 -- 4.45 0.98629 1.789 0.039 0.951 0.176 -- 1.03 0.27630 0.150 0.207 1.569 1.629 -- 1.74 1.42631 0.528 -- -- -- 2.19 0.92 1.45632 1.613 -- -- -- 1.89 0.24 1.85633 0.079 -- -- -- 2.42 3.69 0.54634 0.592 -- -- -- 3.05 0.91 0.81635 0.808 -- -- -- 2.96 3.10 0.59636 1.428 -- -- -- 1.37 4.66 1.36637 -- 1.490 -- -- 2.29 4.81 1.02638 -- 1.763 -- -- 2.49 0.33 1.99639 -- 1.309 -- -- 3.66 2.50 1.27640 -- 1.828 -- -- 2.54 3.24 0.35______________________________________ TABLE 22-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________611 0.0243 0.004 0.011 6 176 35612 0.0015 0.009 0.013 7 132 27613 0.0087 0.007 0.012 4 170 37614 0.0263 0.010 0.006 4 142 24615 0.0050 0.007 0.020 6 176 28616 0.0134 0.005 0.013 1 175 34617 0.0031 0.009 0.019 6 166 29618 0.0129 0.002 0.017 2 152 41619 0.0240 0.007 0.013 3 161 37620 0.0158 0.007 0.013 6 145 39621 0.0137 0.006 0.015 4 133 34622 0.0127 0.003 0.015 2 152 31623 0.0077 0.009 0.010 4 179 29624 0.0089 0.010 0.006 4 144 31625 0.0112 0.008 0.019 1 172 27626 0.0099 0.007 0.009 1 143 24627 0.0003 0.005 0.010 2 133 42628 0.0069 0.009 0.018 5 171 40629 0.0251 0.010 0.013 0 133 35630 0.0202 0.009 0.009 1 174 38631 0.0020 0.002 0.013 5 170 10632 0.0104 0.005 0.013 6 175 19633 0.0109 0.007 0.005 2 166 12634 0.0281 0.006 0.005 6 171 12635 0.0127 0.002 0.001 2 142 19636 0.0043 0.006 0.018 4 158 24637 0.0130 0.008 0.005 6 171 24638 0.0188 0.006 0.007 5 158 25639 0.0025 0.008 0.011 6 149 17640 0.0030 0.004 0.005 1 144 23______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 23-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________641 0.07 0.17 0.66 14.30 0.390 0.93 0.23 0.14 0.04642 0.20 0.18 0.47 14.07 0.774 3.34 0.50 0.26 0.02643 0.30 0.65 0.91 13.22 0.294 3.48 0.75 0.47 0.09644 0.17 0.65 0.61 15.86 0.761 0.77 0.84 0.19 0.20645 0.06 0.06 0.27 7.07 0.039 1.33 0.60 0.09 0.08646 0.22 0.33 0.54 10.71 0.948 1.29 0.85 0.32 0.17647 0.01 0.15 0.50 51.0 0.336 1.78 0.46 0.07 0.08648 0.11 0.17 0.40 7.60 0.529 0.58 0.73 0.49 0.22649 0.19 0.25 0.93 9.53 0.359 0.44 0.51 0.02 0.11650 0.19 0.28 0.35 15.27 0.173 0.85 0.15 0.06 0.04651 0.21 0.13 0.52 16.32 0.798 2.91 0.46 0.28 0.22652 0.21 0.05 0.92 16.90 0.086 1.14 0.29 0.35 0.02653 0.29 0.71 0.63 15.04 0.360 3.24 0.97 0.44 0.11654 0.10 0.41 0.69 8.44 0.952 0.41 0.86 0.23 0.22655 0.17 0.59 0.60 8.03 0.211 2.00 0.27 0.12 0.18656 0.18 0.33 0.99 11.57 0.949 0.86 0.04 0.03 0.19657 0.22 0.29 0.57 17.19 0.536 3.10 0.99 0.37 0.22658 0.09 0.34 0.38 9.48 0.282 1.54 0.99 0.09 0.23659 0.19 0.36 0.70 12.49 0.532 2.26 0.87 0.07 0.05660 0.02 0.21 0.20 11.01 0.622 1.39 0.45 0.25 0.01661 0.28 0.16 0.75 9.37 0.385 3.33 0.07 0.29 0.19662 0.17 0.46 0.21 11.99 0.656 2.64 0.07 0.36 0.19663 0.11 0.22 0.85 16.73 0.273 0.38 0.76 0.38 0.09664 0.16 0.07 0.94 8.41 0.574 0.99 0.04 0.28 0.09665 0.02 0.30 0.76 17.55 0.400 0.62 0.67 0.20 0.15666 0.20 0.36 0.97 9.41 0.081 2.04 0.06 0.33 0.11667 0.07 0.55 0.24 14.37 0.947 3.03 0.96 0.33 0.17668 0.03 0.32 0.83 17.23 0.339 1.41 0.30 0.36 0.17669 0.03 0.72 0.62 15.87 0.096 1.59 0.34 0.11 0.08670 0.16 0.07 0.67 14.75 0.548 3.03 0.94 0.47 0.09______________________________________ TABLE 23-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________641 -- 0.967 -- -- 0.82 4.30 0.78642 -- 0.431 -- -- 2.47 4.79 1.33643 1.039 0.860 -- -- 1.92 1.56 0.81644 1.958 1.934 -- -- 0.75 0.99 1.63645 0.320 1.331 -- -- 0.57 4.70 0.76646 0.776 1.709 -- -- 3.01 2.31 0.66647 1.028 0.752 -- -- 2.48 2.63 1.00648 1.708 1.127 -- -- 3.02 2.50 1.49649 -- -- 1.216 -- 1.42 1.11 0.95650 -- -- 0.082 -- 4.09 4.87 1.77651 -- -- 0.652 -- 0.62 0.97 1.84652 -- -- 0.621 -- 4.67 3.08 0.90653 -- -- 1.640 -- 1.01 0.75 0.43654 -- -- 1.396 -- 3.27 0.43 1.93655 1.643 -- 1.563 -- 1.07 1.32 1.53656 1.141 -- 1.798 -- 3.23 0.26 0.72657 0.131 -- 0.793 -- 4.13 1.22 1.01658 0.304 -- 0.200 -- 0.60 3.44 1.19659 0.304 -- 0.704 -- 3.87 1.33 1.88660 1.823 -- 1.946 -- 3.48 3.63 1.85661 -- 0.176 1.644 -- 1.16 2.52 0.88662 -- 0.786 1.458 -- 3.26 1.88 0.41663 -- 0.819 1.059 -- 4.22 3.38 1.07664 -- 1.909 0.090 -- 3.16 1.36 0.75665 -- 0.777 0.258 -- 4.20 2.31 0.97666 -- 0.072 0.221 -- 4.11 3.01 0.53667 1.272 1.462 1.647 -- 4.49 2.64 0.92668 0.081 1.588 0.181 -- 4.48 2.79 1.83669 1.461 1.159 1.159 -- 0.97 2.71 1.19670 1.063 1.859 1.360 -- 0.47 4.15 0.54______________________________________ TABLE 23-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________641 0.0015 0.005 0.013 6 172 20642 0.0224 0.005 0.015 3 161 17643 0.0162 0.008 0.006 1 139 22644 0.0226 0.007 0.002 2 133 39645 0.0067 0.006 0.011 2 171 19646 0.0088 0.007 0.009 6 180 31647 0.0089 0.009 0.003 7 139 22648 0.0021 0.002 0.010 6 174 32649 0.0132 0.002 0.006 0 165 18650 0.0228 0.008 0.009 1 139 10651 0.0107 0.004 0.014 7 173 11652 0.0018 0.008 0.019 4 170 11653 0.0213 0.008 0.020 4 158 18654 0.0045 0.003 0.005 7 164 19655 0.0212 0.001 0.009 4 167 35656 0.0068 0.005 0.009 4 143 30657 0.0010 0.004 0.013 0 147 13658 0.0288 0.001 0.016 1 155 14659 0.0259 0.009 0.017 5 170 13660 0.0165 0.003 0.010 5 170 37661 0.0118 0.009 0.004 6 133 28662 0.0061 0.008 0.014 0 161 26663 0.0245 0.001 0.009 0 132 21664 0.0173 0.007 0.003 2 149 30665 0.0243 0.005 0.014 4 140 20666 0.0261 0.008 0.009 1 132 8667 0.0022 0.009 0.013 7 154 48668 0.0222 0.007 0.015 5 132 20669 0.0074 0.010 0.002 4 145 45670 0.0275 0.007 0.008 7 170 47______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 24-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________671 0.09 0.57 0.86 5.19 0.536 1.89 0.96 0.38 0.17672 0.06 0.16 0.25 17.61 0.897 2.60 0.23 0.50 0.15673 0.16 0.65 0.72 17.33 0.464 1.27 0.55 0.25 0.12674 0.07 0.73 0.52 8.61 0.571 0.70 0.29 0.05 0.15675 0.02 0.30 0.33 15.51 0.063 1.98 0.28 0.06 0.21676 0.25 0.38 0.82 16.27 0.759 1.27 0.34 0.20 0.02677 0.13 0.07 0.65 8.78 0.012 1.33 0.81 0.39 0.01678 0.06 0.03 0.50 16.98 0.150 1.62 0.55 0.06 0.04679 0.28 0.12 0.64 12.62 0.008 1.61 0.87 0.11 0.05680 0.16 0.60 0.53 13.18 0.919 0.73 0.62 0.45 0.14681 0.08 0.57 0.43 16.48 0.239 3.42 0.14 0.28 0.13682 0.15 0.29 0.63 13.87 0.277 0.88 0.25 0.25 0.24683 0.02 0.41 0.59 16.07 0.377 2.42 0.27 0.02 0.06684 0.08 0.02 0.97 8.22 0.880 2.63 0.58 0.02 0.15685 0.15 0.56 0.85 14.11 0.131 2.58 0.99 0.16 0.24686 0.17 0.35 0.50 5.62 0.952 1.74 0.85 0.12 0.04687 0.24 0.40 0.97 12.92 0.675 1.16 0.48 0.06 0.23688 0.17 0.23 0.96 8.12 0.651 0.38 0.23 0.38 0.18689 0.20 0.07 0.31 13.99 0.707 2.13 0.91 0.04 0.08690 0.28 0.20 0.51 5.39 0.677 0.89 0.39 0.41 0.02691 0.22 0.48 0.99 15.95 0.884 2.69 0.96 0.44 0.07692 0.12 0.78 0.46 5.78 0.681 2.08 0.50 0.04 0.09693 0.07 0.21 0.38 11.85 0.914 0.24 0.35 0.13 0.14694 0.03 0.20 0.22 6.02 0.414 3.17 0.81 0.14 0.07695 0.10 0.23 0.64 12.12 0.513 2.09 0.75 0.45 0.20696 0.08 0.17 0.72 14.91 0.043 3.03 0.98 0.03 0.14697 0.08 0.28 0.72 5.86 0.342 0.53 0.86 0.49 0.19698 0.18 0.43 0.91 8.83 0.252 0.64 0.22 0.30 0.08699 0.05 0.50 0.36 8.64 0.098 1.13 0.86 0.10 0.02700 0.22 0.73 0.53 9.51 0.714 1.50 0.17 0.06 0.08______________________________________ TABLE 24-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________671 0.585 0.375 1.370 -- 2.11 3.79 1.36672 1.672 1.328 1.207 -- 2.69 3.25 1.53673 -- -- -- 1.975 1.41 4.13 0.77674 -- -- -- 1.491 2.36 0.92 0.61675 -- -- -- 0.211 2.28 4.76 1.62676 -- -- -- 0.808 0.37 0.46 1.70677 -- -- -- 0.951 3.09 4.04 0.58678 -- -- -- 0.321 2.40 0.32 0.64679 0.907 -- -- 0.578 4.75 2.92 1.60680 1.795 -- -- 1.402 2.14 3.85 1.38681 0.320 -- -- 0.487 3.42 4.74 1.46682 1.134 -- -- 1.480 2.97 4.79 0.66683 0.888 -- -- 1.045 2.37 0.76 1.37684 1.317 -- -- 1.871 0.88 3.93 1.50685 -- 0.402 -- 1.643 4.94 3.92 1.67686 -- 0.344 -- 1.999 4.09 4.66 0.65687 -- 1.828 -- 1.636 2.38 3.08 0.89688 -- 1.534 -- 1.224 1.44 0.72 0.27689 -- 0.116 -- 0.414 2.81 3.94 0.28690 -- 0.232 -- 0.888 0.98 4.86 0.65691 -- -- 0.816 1.329 4.74 2.62 1.96692 -- -- 1.278 1.395 3.65 1.26 1.24693 -- -- 0.685 1.771 4.21 2.40 1.79694 -- -- 1.689 1.116 3.20 2.85 1.50695 -- -- 0.985 0.118 2.21 4.22 0.99696 -- -- 1.222 1.416 0.44 0.87 1.75697 -- 1.047 0.086 1.724 4.36 4.11 0.80698 -- 1.789 1.247 1.695 1.16 1.09 0.54699 -- 1.128 1.370 1.991 4.41 3.02 0.67700 -- 1.750 0.152 1.312 3.81 1.97 0.90______________________________________ TABLE 24-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________671 0.0028 0.005 0.011 3 135 31672 0.0178 0.008 0.009 6 168 43673 0.0078 0.001 0.017 6 146 29674 0.0281 0.005 0.013 0 173 17675 0.0285 0.004 0.013 4 175 15676 0.0042 0.006 0.014 2 156 19677 0.0250 0.001 0.013 1 144 15678 0.0261 0.001 0.015 5 141 7679 0.0179 0.004 0.019 6 175 21680 0.0253 0.010 0.010 6 148 32681 0.0135 0.006 0.016 5 139 11682 0.0221 0.001 0.004 3 150 26683 0.0017 0.003 0.018 5 158 22684 0.0220 0.005 0.008 6 168 33685 0.0186 0.006 0.009 5 156 22686 0.0158 0.009 0.007 5 150 23687 0.0245 0.008 0.001 1 152 38688 0.0244 0.002 0.006 2 141 31689 0.0252 0.006 0.009 4 169 16690 0.0077 0.002 0.017 2 165 21691 0.0262 0.006 0.007 5 155 28692 0.0165 0.008 0.015 6 167 26693 0.0184 0.001 0.008 6 155 29694 0.0120 0.007 0.013 1 170 27695 0.0221 0.002 0.007 7 167 16696 0.0291 0.002 0.006 2 146 27697 0.0281 0.010 0.016 6 137 35698 0.0141 0.002 0.015 4 167 48699 0.0269 0.004 0.010 6 163 39700 0.0172 0.006 0.017 5 154 37______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 25-1______________________________________STEEL OF INVENTION(Mass. %)No. C Si Mn Cr Mo W V Nb N______________________________________701 0.21 0.24 0.91 9.56 0.450 2.84 0.43 0.35 0.10702 0.11 0.45 0.54 6.45 0.127 2.97 0.52 0.39 0.17703 0.04 0.06 0.91 17.65 0.088 2.98 0.27 0.11 0.12704 0.07 0.50 0.68 15.12 0.185 2.36 0.99 0.40 0.15705 0.02 0.09 0.92 9.65 0.220 0.56 0.55 0.45 0.11706 0.28 0.26 0.70 5.48 0.547 1.95 0.26 0.42 0.08707 0.08 0.10 0.29 13.64 0.508 2.73 0.47 0.23 0.13708 0.08 0.26 0.36 6.01 0.935 2.36 1.00 0.30 0.24709 0.25 0.61 0.78 6.28 0.160 0.27 0.21 0.29 0.23710 0.25 0.25 0.61 6.03 0.523 0.90 0.42 0.13 0.19711 0.02 0.23 0.93 9.59 0.862 2.06 0.48 0.23 0.08712 0.26 0.79 0.39 8.10 0.500 1.49 0.20 0.50 0.09713 0.03 0.64 0.88 12.65 0.286 2.04 0.92 0.38 0.08714 0.01 0.05 0.66 8.10 0.055 3.13 0.02 0.27 0.13715 0.02 0.05 0.39 5.22 0.632 0.88 0.28 0.10 0.18716 0.30 0.53 0.76 8.47 0.369 3.08 0.07 0.02 0.08717 0.07 0.17 0.42 9.12 0.586 0.88 0.70 0.21 0.16718 0.30 0.03 0.45 11.69 0.139 2.02 0.04 0.34 0.02719 0.22 0.37 0.31 13.79 0.332 0.94 0.87 0.08 0.20720 0.07 0.65 0.66 13.50 0.034 2.15 0.11 0.09 0.09______________________________________ TABLE 25-2______________________________________STEEL OF INVENTION(Mass. %)No. Ti Zr Ta Hf Co Ni Cu______________________________________701 -- 1.320 1.239 1.310 3.31 1.89 1.83702 -- 1.487 0.298 1.641 2.09 2.01 0.47703 1.220 -- 0.025 1.004 4.23 3.95 1.02704 1.510 -- 0.055 0.054 1.70 4.49 1.37705 1.549 -- 1.089 1.455 0.90 0.46 0.35706 1.018 -- 0.804 0.923 1.13 0.73 1.26707 1.560 -- 1.858 0.093 1.51 2.03 1.99708 0.886 -- 1.929 0.641 3.71 3.61 0.46709 0.631 1.371 -- 1.234 2.11 2.30 1.77710 1.504 0.654 -- 0.556 0.72 4.48 1.13711 1.160 0.598 -- 0.273 3.54 4.56 0.92712 1.235 1.864 -- 1.048 0.22 1.76 1.77713 1.457 1.158 -- 1.581 4.39 4.95 1.59714 0.470 0.131 -- 1.527 0.82 1.28 0.97715 0.946 0.427 0.199 0.537 0.68 4.31 1.40716 0.571 0.776 0.577 1.322 0.90 1.37 0.81717 1.005 1.793 1.990 0.532 3.01 3.62 0.71718 0.923 1.196 1.157 1.843 1.45 0.69 1.69719 0.972 1.619 0.713 1.907 2.57 3.69 0.72720 1.877 1.728 0.321 1.400 0.80 4.72 0.25______________________________________ TABLE 25-3______________________________________STEEL OF INVENTION(Mass. %)No. P S O D-CRS HAZCRS M %______________________________________701 0.0096 0.010 0.003 6 166 39702 0.0291 0.010 0.004 3 179 32703 0.0261 0.009 0.007 2 169 31704 0.0253 0.006 0.009 5 164 21705 0.0221 0.005 0.007 5 167 40706 0.0117 0.002 0.017 3 131 34707 0.0040 0.007 0.007 6 134 41708 0.0088 0.008 0.003 5 152 35709 0.0064 0.004 0.010 6 165 38710 0.0220 0.007 0.008 4 149 32711 0.0205 0.002 0.001 3 133 26712 0.0270 0.001 0.016 4 144 36713 0.0220 0.003 0.012 6 159 42714 0.0151 0.002 0.013 4 158 29715 0.0162 0.004 0.017 5 166 29716 0.0208 0.009 0.002 7 138 30717 0.0240 0.007 0.002 2 176 52718 0.0208 0.008 0.006 2 157 46719 0.0206 0.004 0.018 0 159 46720 0.0044 0.009 0.017 2 161 52______________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone TABLE 26-1__________________________________________________________________________COMPARATIVE STEEL(Mass. %)C Si Mn Cr Mo W V Nb N Ti Zr Ta Hf Co__________________________________________________________________________721 0.096 0.637 0.307 13.8 0.32 2.21 0.540 0.144 0.026 1.974 -- 0.797 -- --722 0.063 0.070 0.862 17.3 0.04 0.52 0.205 0.011 0.022 - 1.546 -- -- 0.67723 0.025 0.520 0.599 10.8 0.95 1.57 0.684 0.150 0.217 -- 0.002 -- -- --724 0.072 0.339 0.461 8.0 0.94 2.50 0.538 0.211 0.194 -- -- -- -- 4.29725 0.077 0.187 0.497 12.4 0.27 3.22 0.913 0.286 0.222 2.243 0.252 -- 0.001 2.95726 0.012 0.016 0.994 14.6 0.60 2.15 0.099 0.061 0.170 -- 3.105 -- -- 1.86727 0.117 0.032 0.495 6.2 0.39 0.33 0.372 0.035 0.175 -- -- 2.007 -- --728 0.109 0.195 0.328 16.2 0.74 0.69 0.534 0.060 0.090 -- -- 1.559 3.511 4.15729 0.276 0.777 0.640 13.3 0.01 2.61 0.811 0.253 0.016 1.938 -- 1.287 -- --730 0.066 0.013 0.265 5.0 0.16 3.00 0.480 0.229 0.131 -- 1.535 -- 0.180 1.56__________________________________________________________________________ TABLE 26-2__________________________________________________________________________COMPARATIVE STEEL(Mass. %) Addition time of Ti, Zr,Ni Cu P S O D-CRS HAZCRS M % Ta and Hf__________________________________________________________________________721 4.76 -- 0.015 0.004 0.006 42 84 0 During melting step722 -- -- 0.014 0.009 0.006 77 105 1 During melting step723 -- 1.24 0.009 0.001 0.010 81 77 2 During refining step, 10 min. before tapping724 -- 1.57 0.008 0.008 0.013 42 80 0 During refining step, 10 min. before tapping725 -- -- 0.022 0.04 0.14 54 91 71 During refining step, 10 min. before tapping726 -- 1.52 0.024 0.003 0.011 25 85 84 During refining step, 10 min. before tapping727 0.90 1.97 0.023 0.001 0.008 40 93 90 During refining step, 10 min. before tapping728 2.23 -- 0.017 0.002 0.016 39 106 68 During refining step, 10 min. before tapping729 -- -- 0.016 0.003 0.001 29 100 2 During refining step, 10 min. before tapping730 3.56 1.65 0.012 0.003 0.006 36 98 2 During refining step, 10 min. before tapping__________________________________________________________________________ D-CRS: Difference between the creep rupture strength at 600.degree. C. fo 100,000 hours estimated by linear extrapolation of a base steel and that of a weld heataffected zone (MPa) HAZCRS: Creep rupture strength of a weld zone at 600.degree. C. for 100,000 hours estimated by linear extrapolation (MPa) M %: Value of (Ti % + Zr % + Ta % + Hf %) in M of M.sub.23 C.sub.6 type carbides in a weld heataffected zone

POSSIBILITY OF UTILIZATION IN THE INDUSTRY

As described above in detail, the present invention provides a martensitic heat-resisting steel excellent in HAZ-softening resistance and exhibiting a high creep strength at high temperature of at least 550.degree. C. The present invention can, therefore, provide materials at low cost which can withstand operation conditions at high temperature and high pressure in thermal power plant boilers, etc. Accordingly, the present invention extremely contributes to the development of the industry.

Claims

1. A martensitic heat-resisting steel having a tempered martensite structure and excellent in HAZ-softening resistance consisting essentially of, in terms of % by mass, 0.01 to 0.30% of C, 0.02 to 0.80% of Si, 0.20 to 1.00% of Mn, 5.00 to 18.00% of Cr, 0.005 to 1.00% of Mo, 0.20 to 3.50% of W, 0.02 to 1.00% of V, 0.01 to 0.50% of Nb, 0.01 to 0.25% of N, up to 0.030% of P, up to 0.010% of S, up to 0.020% of O, at least one element selected from the group consisting of Ti, Zr, Ta and Hf in an amount of 0.005 to 2.0% for each of the elements, and the balance Fe and unavoidable impurities, the volume of (Ti %+Zr %+Ta %+Hf %) in the metal component M of M.sub.23 C.sub.6 type carbides precipitated in the tempered martensite structure of the steel being from 5 to 65%.

2. The martensitic heat-resisting steel according to claim 1, wherein said steel further consists essentially of, in terms of % by mass, at least one element selected from the group consisting of Co, Ni and Cu in an amount of 0.1 to 5.0% for Co or Ni, and 0.1 to 2.0% for Cu.

3. A process for producing a martensitic heat-resisting steel excellent in HAZ-softening resistance, comprising the steps of

adding at least one element selected from the group consisting of Ti, Zr, Ta and Hf in an amount of 0.005 to 2.0% for each of the elements, in terms of % by mass, to a molten steel consisting essentially of 0.01 to 0.30% of C, 0.02 to 0.80% of Si, 0.20 to 1.00% of Mn, 5.00 to 18.00% of Cr, 0.005 to 1.00% of Mo, 0.20 to 3.50% of W, 0.02 to 1.00% of V, 0.01 to 0.50% of Nb, 0.01 to 0.25% of N, up to 0.030% of P, up to 0.010% of S, up to 0.020% of O, and the balance Fe and unavoidable impurities, during the period from 10 minutes before completion of refining to completion of refining,

casting said molten steel,

hot working the resulting casting,

solution treating the hot worked product thus obtained,

subjecting said hot worked product having been solution treated to cooling stop at a temperature from 950.degree. to 1,000.degree. C. in the course of cooling said hot worked product from the solution treating temperature to room temperature,

holding said hot worked product at the temperature for 5 to 60 minutes, and

tempering said worked product.

4. The process for producing a martensitic heat-resisting steel according to claim 3, wherein said molten steel further consisting essentially of, in terms of % by mass, at least one element selected from the group consisting of Co, Ni and Cu in an amount of 0.1 to 5.0% for Co or Ni, and 0.1 to 2.0% for Cu.

5. The process for producing a martensitic heat-resisting steel according to claim 3, wherein said hot working is rolling for producing a plate product and a tube product.

6. The process for producing a martensitic heat-resisting steel according to claim 3, wherein said hot working is forging.