Patent Application
20240218487
The present invention relates 5XXX series alloy aluminium sheet and their method of making, particularly useful for the automotive industry.
Usually an automotive component such as a car hood is mainly made of two parts: an outer part and an inner part. The first is visible from outside the car and the second is not visible unless for example in case of opening of the hood.
The components need to encompass many requirements among which there are the pedestrian safety and the quality of the surface for painting performance. Therefore, the outer part is usually developed to have a high painting aspect quality. The inner part or automobile hood inner is usually not subjected to the same requirements regarding painting aspect quality. The inner part is usually developed in view of pedestrian safety in case of collision which means in particular low in-service strength. Those parts are usually close to the engine and there is a need for thermal stability. The inner part needs also to be apt to receive a surface treatment.
Various aluminium alloys are used in the form of sheets or blanks for automotive usages. Among these alloys, AA6xxx aluminium alloys series, such as AA6016-T4 are known to combine interesting chemical and mechanical properties such as hardness, strength, forming and even corrosion resistance.
Specific products usually for inner parts without requirements of surface quality have also been developed for improved pedestrian safety.
Patent application WO2006/056481 discloses an aluminium alloy sheet for automotive applications for improved pedestrian safety, having a chemical composition in weight percent: 0.80≤Si≤1.20−0.10≤Fe≤0.30−0.05≤Mn≤0.20−0.10≤Mg≤0.30−u≤0.30−Ti≤0.15− other elements up to 0.05 each, up to 0.15 in total Al balance, in T4 temper condition having a yield strength (Rp) of at least 50 MPa, a uniform elongation (Au) of at least 20% and a total elongation (A80) of at least 22%.
Patent application WO2018/033537 discloses an aluminum alloy for vehicle applications with a moderate strength level, the produced strip showing only a low tendency for curing from the state T4 than can be used for pedestrian impact. The aluminum alloy has the following alloying constituents (in percent by weight): 0.4 wt. %≤Si≤0.55 wt. %, 0.15 wt. %≤Fe≤0.25 wt. %, Cu≤0.06 wt. %, 0.15 wt. %≤Mn≤0.4 wt. %, 0.33 wt. %≤Mg≤0.4 wt. %, Cr≤0.03 wt. %, 0.01 wt. %≤Ti≤0.10 wt. %, the remainder Al and unavoidable impurities of at most 0.05 wt. % individually and at most 0.15 wt. % in total.
The patent application US20120234437 discloses a car component with at least one first component of sheet metal of a first aluminum alloy and at least one second component of sheet metal of a second aluminum alloy, the first and second aluminum alloys are of type AlMgSi and in the sheet metal of the second aluminum alloy a substantial part of the elements Mg and Si, which are required to achieve artificial ageing in solid solution, is present in the form of separate Mg2Si and/or Si particles in order to avoid artificial ageing.
Other approaches to improve pedestrian safety have been to provide clad sheets or other types of composite products.
The patent application EP2328748 relates to an automotive clad sheet product comprising a core layer and at least one clad layer wherein the core comprises an alloy of the following composition in weight %: Mg 0.45-0,8, Si 0.45-0.7, Cu 0.05-0.25, Mn 0.05-0.2, Fe up to 0,35, other elements (or impurities)<0.05 each and <0.15 in total, balance aluminium; and the at least one clad layer comprises an alloy of the following composition in weight %: Mg 0.3-0.7, Si 0.3-0.7, Mn up to 0,15, Fe up to 0.35, other elements (impurities)<0.05 each and <0.15 in total, balance aluminium. However clad products are usually expensive and monolithic products (not cladded) are preferable. The patent application EP2121419 provides a thin vehicle closure panel design that substantially reduces a thickness of a vehicle hood and the impact effect on the head of a pedestrian struck by a motor vehicle by incorporating a foam core positioned between and bonded to the outer and/or the inner panel of the hood shell.
The patent application WO2020/120267 s directed to a method for producing a 6xxx series aluminium sheet comprising the steps of homogenizing an ingot made from a 6XXX series aluminium alloy comprising in wt. % Si: 0.4-0.7, Mg: 0.2-0.4, Mn: 0.05-0.30, Fe: 0.03 to 0.4, Cu up to 0.3, Cr up to 0.05, Zn up to 0.15, Ti up to 0.1 wt %, rest aluminium and unavoidable impurities up to 0.05 each and 0.15 total, rough hot rolling on a reversible mill to a rough hot rolling exit thickness with a rough hot rolling exit temperature less than 420° C., finish hot rolling the ingot to a hot rolling final thickness with a tandem mill and coiling at the hot rolling final thickness with a hot rolling exit temperature less than 300° C., cold rolling to obtain a cold rolled sheet. The products obtained according to the method of the invention are particularly useful for automobile hood inners as they have the requested mechanical properties for pedestrian safety and surface quality.
AA5xxx alloys which do not necessitate a solution heat treatment such as T4 temper may be an interesting alternative.
The patent application EP0593034 A2 discloses an aluminum alloy sheet which has a high level of strength and excels in formability consisting essentially of about 3 to 10 wt % of Mg and a total of about 0.3 to 2.0 wt % of Fe and Si, the aluminum alloy sheet being provided with a lubricant surface coating and having a sliding resistance of not more than about 0.11. It may also contain strengthening elements, such as Cu, Mn, Cr, Zr and Ti. The patent application WO2011/011744 discloses a 5xxx aluminum alloy consisting essentially of: from about 2.5 wt. % to about 7 wt. % Mg; from about 0.05 wt. % to about 2 wt. % Cu; from about 0.3 wt. % to about 1.5 wt. % Mn; optionally up to 2.0 wt. % Zn; optionally up to 1.0 wt. % total of additives, wherein the additives are selected from the group consisting of Zr, Cr, V, Sc, Hf, Ti, B, C, Ca, Sr, Be, Bi, Cd, Ge, In, Mo, Nb, Ni, Sn, Y; and the balance being aluminum and unavoidable impurities.
The patent application WO2016/077044 discloses an aluminum alloy comprising ≥1.5% Mg, ≤ 0.8% Cu, ≤ 0.5% Fe, ≤ 0.4% Mn, 0.2-0.4% Si, ≤ 0.5% Zn, and ≤ 0.25% Cr by weight, the remainder being Al and unavoidable impurities, produced by a process comprising cold-rolling to a final gauge and solutionizing at temperatures above 480° C., wherein the process comprises specifically T4 temper.
The patent application WO2018/005442 discloses an aluminum alloy, comprising 0.10-0.30 wt. % Fe, 0.10-0.30 wt. % Si, 0-0.25 wt. % Cr,2.0-3.0 wt. % Mg, 0.05-0.10 wt. % Mn, 0.02-0.06 wt. % Cu, unavoidable impurities up to 0.05 wt. % for each impurity, up to 0.15 wt. % for total impurities, and the balance aluminum.
The patent application WO98/24940 discloses an aluminium alloy in the AA5XXX series has the composition: Si 0.10-0.25%; Fe 0.18-0.30%; Cu up to 0.5%; Mn 0.4-0.7%; Mg 3.0-3.5%; Cr up to 0.2%; and Ti up to 0.1%.
The patent application WO2008/010352 discloses a high strength aluminum alloy sheet having a chemical composition containing Mg: 2.0 to 3.3 mass %, Mn: 0.1 to 0.5 mass %, and Fe: 0.2 to 1.0 mass %, having a balance of unavoidable impurities and Al.
The patent application US20070217943 A1 discloses an aluminum alloy sheet consisting of 2.0-8.0 wt % of Mg, 0.06-0.2 wt % of Si, 0.1-0.5 wt % of Fe, 0.1-0.5 wt % of Mn, and the balance of Al and unavoidable impurities.
WO2004/090184 discloses an aluminum alloy which has the following alloy proportions in weight percentages: 2<=Mg<=5, Mn<=0.5, Cr<=0.35, Si<=0.4, Fe<=0.4, Cu <=0.3, Zn<=0.3, Ti<=0.15, other elements totaling no more than 0.15 and separately not exceeding 0.05, and the remainder consists of Al.
Among uses of aluminum alloys as automotive components are reinforcements which are located at specific locations and enable local improvement of mechanical properties.
Inners may be in specific cases considered as reinforcements. In electric vehicles these reinforcements can also be located around the battery.
Patent application JP09279281 discloses a problem to solved: To produce an Al alloy baking finished sheet for a can top material excellent in corrosion resistance without deteriorating its strength and the formability of a rivet or the like.
SOLUTION: This Al alloy baking finished sheet has a comprising containing by weight, 2.0 to <3.0% Mg, 0.20 to 0.70% Mn, 0.01 to 0.15% Cu, <+0.35% Fe and <+0.20% Si, also satisfying Mn/Si>=2.0, furthermore containing, one or two kinds of <+0.10% Cr and <+0.05% Ti, and the balance Al with inevitable impurities. Then, in the metallic structure of the cross section parallel to the rolling direction, the area fraction of Mg2Si compounds having >=1·mu·m average grain size is regulated to <+1.2%, and the amount of precipitates having >=0.1·mu·m average grain size among precipitates containing Cu is regulated to <+0.40% by the amount expressed in terms of Cu.
Patent application JP07197176 discloses: To produce an Al alloy sheet for food can full open-end having excellent can openability.
CONSTITUTION: This Al alloy sheet for food can full open-end has the chemical composition composed of 1.70-2.70% Mg, 0.30-0.60% Mn, 0.10-0.30% Fe as the essential components, and as necessary, further containing one or more kinds of <+0.30% Si, <+0.20% Ti and <+0.20% Cu and the balance Al with inevitable impurities and 0.3-1.0% area possessing ratio with Al—Fe—Mn intermetallic compound of 3-20·mu·m when observing from the surface of the product sheet and has excellent can openability. After executing homogenizing treatment at 470-530 deg.C to an Al alloy cast ingot having this chemical composition, hot-rolling is applied, and further, cold-rolling is applied at >=30%, and after applying intermediate annealing in the temp. range of 360-540 deg.C, the cold-rolling is applied at 30-80% to produce the objective Al alloy sheet adjustable its strength without applying the annealing.
Patent application JP2002212661 discloses a problem to solved: To provide an aluminum alloy sheet for embossing used for building materials such as a siding material, and an aluminum alloy coated sheet in which cracking is hard to be generated in embossing, and which is firm so as to correspond to the request for thinning.
SOLUTION: An aluminum alloy sheet for embossing consists of a soft material having a composition containing 1.3 to 2.3% Mg, and in which the content of Si is controlled to <+0.3%, and Fe to <+0.3%, and the balance Al with inevitable impurities, and in which elongation in a direction perpendicular to the rolling direction is >=27%, and tensile strength is >=140 N/mm2. In addition to the above the aluminum alloy sheet for embossing contains one or more selected from 0.06 to 0.3% Cu, 0.06 to 0.3% Mn and 0.06 to 0.3% Cr. Aluminum alloy coated sheets for embossing is obtained by further applying coating to the surfaces of the above aluminum alloy sheets.
Patent application WO2020/185920 discloses a new aluminum alloy products and methods of making these alloys. The aluminum alloy products are age-hardenable, display high strength and formability, and allow for the use of recycled scrap. The aluminum alloys can serve as the core in a clad aluminum alloy product. The alloy products can be used in a variety of applications, including automotive, transportation, and electronics applications.
Patent application WO2005/080619 discloses A method of making aluminum alloy sheet in a continuous in-line process is provided. A continuously-cast aluminum alloy strip is optionally quenched, hot or warm rolled, annealed or heat-treated in-line, optionally quenched, and preferably coiled, with additional hot, warm or cold rolling steps as needed to reach the desired gauge. The process can be used to make aluminum alloy sheet of T or O temper having the desired properties, in a much shorter processing time. Patent application WO2006/026330 discloses a method for producing aluminum vehicular structural parts or members such as from molten aluminum alloy using a continuous caster to cast the alloy into a slab. The method comprises providing a molten aluminum alloy consisting essentially of 2.7 to 3.6 wt. % Mg, 0.1 to 0.4 wt. % Mn, 0.02 to 0.2 wt. % Si, 0.05 to 0.30 wt. % Fe, 0.1 wt. % max. Cu, 0.25 wt. % max. Cr, 0.2 wt. % max. Zn, 0.15 wt. % max. Ti, the remainder aluminum, incidental elements and impurities and providing a continuous caster such as a belt caster, block caster or roll caster for continuously casting the molten aluminum alloy. The molten aluminum alloy is cast into a slab which is rolled into a sheet product and then annealed. The sheet has an improved distribution of intermetallic particles (Al—Fe, Al—Fe—Mn or Mg2Si) and improved formability. Thereafter, the sheet product is formed into the vehicular structural part or member with sufficient strength and formability required by automotive industry.
Patent application FR2878255 disclosed an aluminium alloy sheet for automotive applications for improved pedestrian safety, having a chemical composition in weight percent: −0.80=Si=1.20−0.10=Fe=0.30−0.05=Mn=0.20−0.10=Mg=0.30−Cu=0.30−Ti=0.15− other elements up to 0.05 each, up to 0.15 in total Al balance, in T4 temper condition having a yield strength (Rp) of at least 50 MPa, a uniform elongation (Au) of at least 20% and a total elongation (A80) of at least 22%.
There is a need in the automotive industry for an improved monolithic aluminium sheet product which combines careful balance between different criteria: controlled strength for the car mechanical properties and pedestrian safety, which is related to low in-service strength, as well as forming ability and thermal stability.
A first object of the invention is a monolithic aluminium sheet made of a 5xxx series aluminium sheet comprising in wt. %
Another object of the invention is a method for producing a monolithic 5xxx series aluminium sheet according to the invention comprising the steps of
Still another object of the invention is the use of a 5xxx series aluminium sheet according to the invention for automobile manufacturing preferably as an automotive inner and/or a reinforcement.
All aluminium alloys referred to in the following are designated using the rules and designations defined by the Aluminium Association in Registration Record Series that it publishes regularly, unless mentioned otherwise.
Metallurgical tempers referred to are designated using the European standard EN-515.
All the alloy compositions are provided in weight % (wt. %).
Unless otherwise specified, the definitions of standard EN 12258 (2012) apply.
The tensile tests were performed according to ISO/DIS 6892-1.
The Lankford coefficient, also called r value or anisotropy coefficient or perpendicular anisotropy or plastic strain ratio is measured according to DIN EN ISO 10113. It is the ratio of the true plastic width strain &b to the true plastic thickness strain &a in the uniform elongation region of a sample subjected to uniaxial tensile test.
The crystallographic texture can be described by a 3-dimensional mathematical function. This function is known in the trade as the Orientation Density Function (ODF). It is defined as the volume fraction of material dV/V having a g±dg orientation:
where (ϕ1,Φ,ϕ2) are the Euler angles describing the orientation g.
The ODF of each sheet was measured by using the method of spherical harmonics from four pole figures measured by X-ray diffraction on a conventional texture goniometer. In the context of the invention the pole figure measurements were performed on the full thickness of the considered sample. Similarly, in order to obtain statistically representative measurements, the sample size was adapted to the grain size.
To simplify the information in the ODF the volume fraction of crystallites that have a specific orientation is calculated. To do this, one arbitrarily defines the reference orientation and an angle of maximum disorientation around this orientation. The ODF is then integrated into the domain so defined, which makes it possible to deduce the relative volume of orientations in this domain relative to the total volume. The present inventor used a tolerance of 15° around “cube”, “R”, “Q” and “CH” orientations in order to describe the texture obtained. The “cube”, “brass”, “Q” and “CH” crystallographic orientations are known to those skilled in the art and are described in the Table 1 below.
The inventors have found improved 5xxx aluminium alloy sheets which combine careful balance between different criteria: controlled strength for the car mechanical properties and pedestrian safety as well as sufficient surface quality. The products obtained by the method of the invention are monolithic, i.e. not cladded, and combine high pedestrian safety properties and good formability properties, such as good drawability.
The Mg content is from 1.7 wt. % to 2.1 wt. % and preferably from 1.8 wt. % to 2.0 wt. %. Mg is the main alloying element of the alloy and it contributes to strength improvement. When the Mg content is under 1.7% wt. %, strength improvement may be insufficient. On the other hand, a content exceeding 2.1 wt. % may result in a strength detrimental to pedestrian safety. Minimum Mg content of 1.8 wt. %, or 1.82 wt. % or 1.85 wt. % may be advantageous. Maximum Mg content of 2.0 wt. %, or 1.95 wt. % or 1.93 wt. % may be advantageous. In an embodiment the Mg content is from 1.8 wt. % to 2.0 wt. %.
Mn is also an effective element for strength improvement, crystal grain refining and structure stabilization. The Mn content is from 0.1 wt. % to 0.5 wt. % and preferably from 0.2 wt. % to 0.5 wt. %, and more preferably from 0.35 wt. % to 0.45 wt. %.
When the Mn content is under 0.1 wt. %, the aforementioned effect is insufficient. On the other hand, a Mn content exceeding 0.5 wt. % may not only cause a saturation of the above effect but also cause the generation of multiple intermetallic compounds that could have an adverse effect on formability. Minimum Mn content of 0.2 wt. %, or 0.26 wt. % or 0.30 wt. % or 0.32 wt. % or 0.35 wt. % may be advantageous. Maximum Mn content of 0.50 wt. %, or 0.48 wt. % or 0.45 wt. % may be advantageous. In an embodiment the Mn content is from 0.2 wt. % to 0.5 wt.
The control of Fe is critical to reach the desired properties of the sheets of the invention. The Fe content is from 0.10 wt. % to 0.22 wt. % and preferably from 0.12 wt. % to 0.20 wt. %.
The present inventors have found that unexpectedly an Fe content above 0.22 wt. % and even above 0.20 wt. % results in a deterioration of the Lankford coefficient which renders forming ability to decrease. Although they are not bound to a particular theory the present inventors believe that this behaviour may be related to the influence of Fe on cube texture development. A Fe content under 0.10 wt. % may not produce a sufficient effect while an Fe content above 0.22 wt. % may not sufficiently promote cube texture. Consequently, the Fe content is set within a range of 0.10 wt. % to 0.22 wt. % and preferably 0.12 wt. % to 0.20 wt. %. Minimum Fe content of 0.13 wt. %, or 0.14 wt. % or 0.15 wt. % may be advantageous. Maximum Fe content of 0.20 wt. %, or 0.19 wt. % or 0.18 wt. % may be advantageous.
The Si content is from 0.05 wt. % to 0.25 wt. % and preferably from 0.08 wt. % to 0.20 wt. %. Excessive addition of Si may generate more Mg2Si phases that could have an adverse effect on formability. Minimum Si content of 0.09 wt. %, or 0.10 wt. % or 0.12 wt. % may be advantageous. Maximum Si content of 0.20 wt. %, or 0.19 wt. % or 0.18 wt. % may be advantageous.
The Cu content is from 0.01 wt. % to 0.20 wt. % and preferably from 0.02 wt. % to 0.15 wt. %. Minimum Cu content of 0.02 wt. %, or 0.03 wt. % or 0.04 wt. % may be advantageous as Cu in solid solution may be beneficial for formability. Maximum Cu content of 0.15 wt. %, or 0.10 wt. % or 0.08 wt. % may be advantageous as formation of Cu containing phases may have an adverse effect on formability. In an embodiment the Cu content is from 0.04 wt. % to 0.08 wt. %.
The Cr content is up to 0.1 wt. %, preferably up to 0.05 and more preferably up to 0.03 wt. %. In an embodiment some Cr may be added for strength improvement, crystal grain refining and structure stabilization with a content from 0.01 wt. % to 0.04 wt %, preferably 0.03 wt. %. In another embodiment the Cr content is less than 0.01 wt. %.
Zn may be added up to 0.15 wt. % and preferably up to 0.10 wt. % without departing from the advantages of the invention. In an embodiment Zn is among the unavoidable impurities.
Zr may be added up to 0.1 wt. % and preferably up to 0.05 wt. % without departing from the advantages of the invention. In an embodiment Zr is among the unavoidable impurities.
Grain refiners comprising Ti are typically added with a total Ti content of up to 0.05 wt. % and preferably between 0.005 and 0.04 wt. % and even more preferably between 0.01 and 0.03 wt. %.
The rest is aluminium and unavoidable impurities up to 0.05 wt. % each and 0.15 wt. % total.
According to the invention, an ingot is prepared by casting, typically Direct-Chill casting, using 5xxx series aluminium alloys of the invention. The ingot thickness is preferably at least 250 mm, or at least 350 mm and preferentially a very thick gauge ingot with a thickness of at least 400 mm, or even at least 500 mm or 600 mm in order to improve the productivity of the process. Preferably the ingot is from 1000 to 2000 mm in width and 2000 to 8000 mm in length. Preferably the ingot is scalped.
The ingot is then pre-heated typically at a temperature between 440° C. and 520° C. and hot rolled in two successive steps in order to obtain a sheet with a first hot rolling step on a reversible rolling mill also known as roughing mill up to a thickness of typically between 12 and 40 mm and a second hot rolling step on a tandem mill also known as finishing mill up to a thickness of typically between 3 and 12 mm. A tandem mill is a rolling mill in which several cages supporting rolling mill rolls, typically 2, 3, 4 or 5 act successively (“in tandem”). According to the invention rough hot rolling on the reversible mill is done with a rough hot rolling entry temperature of more than 440° C. and preferably more than 460° ° C. The first step on a reversible mill can be carried out on one or even two reversible mills placed successively.
In the second hot rolling step the final temperature which is the hot rolling exit temperature should be at least 280° C., preferably at least 300° C. and most preferably at least 335° C. so that preferably the hot rolled sheet obtained after finish hot rolling exhibit at least 50% recrystallization rate and preferably at least 80% recrystallization rate.
Cold rolling is realized directly after the hot rolling step to further reduce the thickness of the aluminium sheets. With the method of the invention annealing after hot rolling or during cold rolling is not necessary to obtain sufficient strength, formability, surface quality and corrosion resistance. Preferably no annealing after hot rolling or during cold rolling is carried out. The sheet directly obtained after cold rolling is referred to as the cold rolled sheet. The cold rolled sheet thickness is typically between 0.5 and 2.5 mm and preferably between 0.7 and 2 mm.
In an embodiment, the cold rolling reduction is at least 40%, or at least 50%. Typically, the cold rolling reduction is at most 70%.
Advantageous embodiments of cold rolling reduction may enable to obtain improved mechanical properties in particular advantageous Lankford coefficient.
After cold rolling, the cold rolled sheet is preferably annealed in order to obtain a O temper which has a fully recrystallized microstructure, preferably in a continuous annealing line. Preferably the continuous annealing line is operated in such a way that a temperature of at least 320° C., preferably at least 340° C. and at most 500° C. or preferably at most 440° C. is reached by the sheet, most preferably between 360° C. and 400° C.
Typically, the continuous annealing line is operated such that the heating rate of the sheet is at least 10° C./s and the time above 340° C. is between 5 s and 25 s. The coiling temperature after annealing is preferably up to 85° C., preferably up to 65° C. and more preferably between 40° C. and 60° C.
Alternatively, the annealing may be carried out by batch annealing at a temperature of at most 440° C.
After annealing the sheet may be cut and formed to its final shape, painted and bake hardened.
In another embodiment, a thermal treatment is carried to obtain a H2X temper, preferably a H24 temper.
The 5xxx series aluminium sheets of the invention in the O temper have a Lankford coefficient of at least 0.605, preferably of at least 0.610. In an embodiment wherein the maximum Fe content is 0.20 wt. %, the sheets of the invention in the O temper have Lankford coefficient of at least 0.615. The 5xxx series aluminium sheets of the invention in the O temper have a volume fraction of cube texture of at least 13%, preferably 13.0%, preferably of at least 14%, preferably 14.0%, preferentially of at least 15% and preferably at least 15.0%. The 5xxx series aluminium sheets of the invention in the O temper have a volume fraction of R texture of at most 11.0%, preferably of at most 10.0%. In an embodiment wherein the maximum Fe content is 0.20 wt. %, the sheets of the invention in the O temper have a volume fraction of cube texture of at least 14%, preferably 14.0%, preferentially of at least 15% and preferably 15.0%. In an embodiment wherein the maximum Fe content is 0.20 wt. %, the sheets of the invention in the O temper have a volume fraction of R texture of at most 10.0%. The products of the invention in the O temper have preferably a TYS in the LT direction, referred to as TYS(LT)o, between 50 MPa and 100 MPa, advantageously between 60 MPa and 98 MPa and preferably between 65 MPa and 95 MPa.
The products of the invention in the O temper have after bake hardening (5% stretching and 20 min at 185° C.), a TYS in the LT direction referred to as TYS(LT)BH, between 90 MPa and 150 MPa, advantageously between 95 MPa and 140 MPa and preferably between 100 MPa and 135 MPa.
The use of the 5xxx series aluminium sheets according to the invention for automobile manufacturing is advantageous, in particular for applications requesting low strength in service. In particular, the use of the sheets according to the invention as an automotive inner and/or reinforcement preferably a hood inner, which need to meet pedestrian safety requirement, is advantageous.
In this example several ingots with an alloy having the composition disclosed in Table 2 were cast by DC-casting technology.
The ingots were pre-heated at 490° C. and hot rolled with a starting temperature as disclosed in Table 3.
The recrystallization rate of the hot rolled strips after hot rolling was more than 50%. The sheets were annealed at 380° C. in a continuous annealing line to a fully recrystallized O-temper and conversion coated. The sheets are fully recrystallized as shown in the
The mechanical properties are provided in Table 4.
The 0.2% tensile yield strength, TYS, and ultimate tensile strength, UTS, of the O temper and bake hardened sheets (5% stretching and 20 min at 185° C.) from those O temper sheets were determined in the transverse direction using methods known to one of ordinary skill in the art. The tensile tests were performed according to ISO/DIS 6892-1. The results are provided in Table 4.
The Lankford coefficient measured according to ISO 10113, and the volume fraction of the texture components identified previously are provided in Table 5 when available.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR2104165 | Apr 2021 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/060442 | 4/20/2022 | WO |
