STAINLESS STEEL ALLOY FOR GOLF CLUB HEAD

Abstract

A stainless steel alloy adapted for a golf club head includes 0.03 wt % of carbon, 0.01 wt % of phosphorus, 0.1 wt % of silicon, 0.05 wt % of calcium, 0.03 wt % of zirconium, 0.1 wt % of manganese, 0.01 wt % of sulfur, 4 wt % to 5.1 wt % of molybdenum, 18 wt % to 19 wt % of nickel, 7 wt % to 12 wt % of cobalt, 0.05 wt % to 0.15 wt % of aluminum, 0.1 wt % to 0.8 wt % of titanium, and a balance of iron based on 100 wt % of the stainless steel alloy, wherein the content of iron is more than 0 wt %.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Taiwanese Patent Application No. 102135351, filed on Sep. 30, 2013.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a stainless steel alloy, more particularly to a stainless steel alloy adapted for a golf club head.

2. Description of the Related Art

Golf sport involves a player twisting his/her waist to swing a golf club and strike a golf ball using a golf club head. Thus, in addition to having relatively high mechanical strength and abrasion resistance to enhance stroke stability, the golf club head is required to have a suitable weight to minimize player fatigue when swinging the golf club. Furthermore, in order to satisfy general requirements of golfers, an increase in manufacturing cost needs to be avoided when making the golf club head with good mechanical strength and abrasion resistance. Therefore, the golf equipment industry has been aggressive in searching and developing new materials for golf club heads, particularly in alloys having different compositions to prepare the golf club head with various properties.

Taiwan Patent Publication No. 200630141 discloses an alloy material (referred as a stainless steel alloy hereinafter) for manufacturing the golf club head. The stainless steel alloy includes carbon in an amount ranging from 0.08 wt % to 0.15 wt %, silicon in an amount ranging from 0.5 wt % to 1.5 wt %, manganese in an amount ranging from 0.4 wt % to 1.2 wt %, copper in an amount less than 0.55 wt %, nickel in an amount ranging from 3.5 wt % to 6.0 wt %, chromium in an amount ranging from 13.5 wt % to 17.0 wt %, molybdenum in an amount ranging from 1.5 wt % to 2.6 wt %, nitrogen in an amount ranging from 0.07 wt % to 0.13 wt %, and a balance of iron based on 100 wt % of the stainless steel alloy. The golf club head made from the stainless steel alloy disclosed in Taiwan Patent Publication No. 200630141 has a tensile strength ranging from 216.9 ksi to 219.2 ksi (1495.8 Mpa to 1511.7 Mpa), and a yield strength ranging from 175.8 ksi to 180.9 ksi (1212.36 Mpa to 1247 Mpa). However, the overall strength of the golf club head made from the aforesaid stainless steel alloy is not rigid enough to maintain its original shape and is thus susceptible to deformation.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a stainless steel alloy for use in a golf club head.

According to a first aspect of this invention, there is provided a stainless steel alloy adapted for a golf club head. The stainless steel alloy includes carbon in an amount of 0.03 wt %; phosphorus in an amount of 0.01 wt %; silicon in an amount of 0.1 wt %; calcium in an amount of 0.05 wt %; zirconium in an amount of 0.03 wt %; manganese in an amount of 0.1 wt %; sulfur in an amount of 0.01 wt %; molybdenum in an amount ranging from 4 wt % to 5.1 wt %; nickel in an amount ranging from 18 wt % to 19 wt %; cobalt in an amount ranging from 7 wt % to 12 wt %; aluminum in an amount ranging from 0.05 wt % to 0.15 wt %; titanium in an amount ranging from 0.1 wt % to 0.8; and a balance of iron based on 100 wt % of the stainless steel alloy, wherein the content of iron is more than 0 wt %.

According to a second aspect of this invention, there is provided a stainless steel alloy adapted for a golf club head. The stainless steel alloy includes carbon in an amount ranging from 0.024 wt % to 0.036 wt %; phosphorus in an amount ranging from 0.008 wt % to 0.012 wt %; silicon in an amount ranging from 0.08 wt % to 0.12 wt %; calcium in an amount ranging from 0.04 wt % to 0.06 wt %; zirconium in an amount ranging from 0.024 wt % to 0.036 wt %; manganese in an amount ranging from 0.08 wt % to 0.12 wt %; sulfur in an amount ranging from 0.008 wt % to 0.012 wt %; molybdenum in an amount ranging from 4 wt % to 5.1 wt %; nickel in an amount ranging from 18 wt % to 19 wt %; cobalt in an amount ranging from 7 wt % to 12 wt %; aluminum in an amount ranging from 0.05 wt % to 0.15 wt %; titanium in an amount ranging from 0.1 wt % to 0.8 wt %; and a balance of iron based on 100 wt % of the stainless steel alloy, wherein the content of iron is more than 0 wt %.

In the present invention, addition of silicon may increase the flowability of the stainless steel alloy during a forming process. Addition of titanium and molybdenum may enhance the mechanical strength and abrasive resistance of the stainless steel alloy by virtue of fine crystal grains, so that a golf club head having superior mechanical strength and abrasive resistance may be manufactured.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A stainless steel alloy adapted for a golf club head according to the present invention includes:

carbon in an amount ranging from 0.024 wt % to 0.036 wt %, preferably ranging from 0.027 wt % to 0.033 wt %, more preferably ranging from 0.0285 wt to 0.0315 wt %, and most preferably of 0.03 wt %;

phosphorus in an amount ranging from 0.008 wt % to 0.012 wt %, preferably ranging from 0.009 wt % to 0.011 wt %, more preferably ranging from 0.0095 wt % to 0.0105 wt %, and most preferably of 0.01 wt %;

silicon in an amount ranging from 0.08 wt % to 0.12 wt %, preferably ranging from 0.09 wt % to 0.11 wt %, more preferably ranging from 0.095 wt % to 0.105 wt %, and most preferably of 0.1 wt %;

calcium in an amount ranging from 0.04 wt % to 0.06 wt %, preferably ranging from 0.045 wt % to 0.055 wt %, more preferably ranging from 0.0475 wt % to 0.0525 wt %, and most preferably of 0.05 wt %;

zirconium in an amount ranging from 0.024 wt % to 0.036 wt %, preferably ranging from 0.027 wt % to 0.033 wt %, more preferably ranging from 0.0285 wt to 0.0315 wt %, and most preferably of 0.03 wt %;

manganese in an amount ranging from 0.08 wt % to 0.12 wt %, preferably ranging from 0.09 wt % to 0.11 wt %, more preferably ranging from 0.095 wt % to 0.105 wt %, and most preferably of 0.1 wt %;

sulfur in an amount ranging from 0.008 wt % to 0.012 wt %, preferably ranging from 0.009 wt % to 0.011 wt %, more preferably ranging from 0.0095 wt % to 0.0105 wt %, and most preferably of 0.01 wt %;

molybdenum in an amount ranging from 4 wt % to 5.1 wt %;

nickel in an amount ranging from 18 wt % to 19 wt %;

cobalt in an amount ranging from 7 wt % to 12 wt %;

aluminum in an amount ranging from 0.05 wt % to 0.15 wt %;

titanium in an amount ranging from 0.1 wt % to 0.8 wt %; and

a balance of iron based on 100 wt % of the stainless steel alloy, wherein the content of iron is more than 0 wt %.

In addition to precipitate carbide, carbon is an element in a stationary phase of austenite (referred as α-Fe hereinafter). While carbon content is increasing, ferrite (referred as γ-Fe hereinafter) is decreasing and α-Fe is more stable.

Silicon could prevent void formation, improve contraction, and enhance flowability of steel fluid. Therefore, the aforesaid specific amount of silicon is added to increase flowability of the stainless steel alloy and improve the alloy casting processability.

Titanium and carbon are liable to form into stable carbide, enhance the precipitation strengthening of the stainless steel alloy, and inhibit overgrowth of crystal grains in the alloy so as to maintain a relatively fine size of the crystal grains in the alloy. Therefore, the mechanical strength and abrasive resistance of the golf club head made from the stainless steel alloy of the present invention may be improved.

Manganese combines with sulfur easily to eliminate hot shortness that is generated by sulfur affecting the stainless steel alloy, and manganese could remove the oxide in the stainless steel alloy. Therefore, manganese usually coexists with iron. In addition, manganese could stabilize the α-Fe having FCC (face-centered cubic) structure. When the aforesaid specific amount of manganese is added to the stainless steel alloy of the present invention, the hot shortness may be eliminated and the alloy casting processability may be improved.

Molybdenum increases hot strength, creep strength and hot hardness of the stainless steel alloy, and thus, the golf club head could be made to have increased abrasion resistance and strength.

Nickel is added to the stainless steel alloy to enhance anticorrosive and anti-oxidative properties and stabilize the α-Fe having FCC structure of the stainless steel alloy.

Cobalt is an essential element added to super-hard high-speed steel and non-super-hard high-speed steel nowadays, and may increase secondary hardenability, red hardness, and hot hardness. Since cobalt dissolves in α-Fe and γ-Fe to enhance covalent bonds of Co—Fe bond and Fe—Fe bond, no matter at room temperature or at high temperature, cobalt could enhance a substrate of alloy and raise a melting point of iron-based alloy.

Aluminum is an excellent deoxidizer which could inhibit overgrowth of the crystal grain in the stainless steel alloy forming dispersive oxide and nitride, thereby maintaining the stainless steel alloy with a small grain size that enhances ductility, workability and toughness of the stainless steel alloy.

Compositions of the stainless steel alloys in Examples 1 to 3 according this invention are listed in Table 1.

TABLE 1
Examples	C	P	Si	Ca	Zr	Mn	S	Mo	Ni	Co	Al	Ti	Iron
Ex. 1	0.03	0.01	0.1	0.05	0.03	0.1	0.01	4.0-5.1	18-19	7-12	0.05-0.15	0.1-0.3	63.12-70.52
Ex. 2	0.03	0.01	0.1	0.05	0.03	0.1	0.01	4.0-5.1	18-19	7-12	0.05-0.15	0.3-0.5	62.92-70.32
Ex. 3	0.03	0.01	0.1	0.05	0.03	0.1	0.01	4.0-5.1	18-19	7-12	0.05-0.15	0.5-0.8	62.62-70.12

The golf club head can be made from the alloy of the present invention using a conventional method for fabricating a golf club head that includes a former processing stage and a latter processing stage. The former processing stage involves precision casting technology, and generally includes the steps of mold-making, wax injection, hanging, dipping, dewaxing, casting, cutting, heat treating, etc. The latter processing stage includes the steps of surface grinding, washing, lacquering, punching, embedding, assembling, torque testing, polishing, etc.

• • The golf club head made from the stainless steel alloy of the present invention has the following advantages:
  • 1. Mechanical strength: manganese, carbon, and titanium were added to the stainless steel alloys in specific amounts listed in Table 1, and tensile strength is 1624 MPa and yield strength is 1616 MPa as shown in Table 2. Therefore, the golf club head made from the stainless steel alloys of the present invention may be made with the best conditions for satisfying consumers' requirements.
  • 2. Corrosion resistance: a substantial amount of nickel was added to the stainless steel alloys to achieve superior atmospheric corrosion resistance.

Table 2 shows performances of tensile strength, yield strength, and elongation in Examples 1 to 3 and Comparative Example, wherein the stainless steel alloys of the present invention are represented as Examples 1 to 3 and that of the prior art is represented as Comparative Example. Referring to the results in Table 2, the golf club head made from the stainless steel alloys of the present invention has superior tensile strength and yield strength.

	TABLE 2
	Example and	Tensile	Yield
	Comparative	strength	strength	Elongation	Density
	Examples	(MPa)	(MPa)	(%)	(g/cm3)
	Example 1	1624	1616	10	7.95-8.15
	Example 2	1758	1724	12	7.95-8.15
	Example 3	2027	1999	11	7.95-8.15
	Comparative	1511	1247	22.4	—
	Example

To sum up, in the stainless steel alloy adapted for a golf club head according to this invention, addition of silicon may increase the flowability in the stainless steel alloy, and addition of titanium and molybdenum may enhance the mechanical strength of the stainless steel alloy. Moreover, addition of aluminum may stabilize the ductility of the stainless steel alloy, so that the ductility would not be considerably decreased when the strength of the stainless steel alloy is increased. Accordingly, the golf club head made from the stainless steel alloy according to the present invention has comparatively lower processing cost, superior processability, and abrasion resistance relative to that made from a conventional stainless steel alloy.

While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.

Claims

1. A stainless steel alloy adapted for a golf club head, comprising: carbon in an amount of 0.03 wt %;phosphorus in an amount of 0.01 wt %;silicon in an amount of 0.1 wt %;calcium in an amount of 0.05 wt %;zirconium in an amount of 0.03 wt %;manganese in an amount of 0.1 wt %;sulfur in an amount of 0.01 wt %;molybdenum in an amount ranging from 4 wt % to 5.1 wt %;nickel in an amount ranging from 18 wt % to 19 wt %;cobalt in an amount ranging from 7 wt % to 12 wt %;aluminum in an amount ranging from 0.05 wt % to 0.15 wt %;titanium in an amount ranging from 0.1 wt % to 0.8; anda balance of iron based on 100 wt % of said stainless steel alloy,wherein the content of iron is more than 0 wt %.

2. The stainless steel alloy according to claim 1, wherein said stainless steel alloy has a density ranging from 7.95 g/cm3 to 8.15 g/cm3.

3. A stainless steel alloy adapted for a golf club head, comprising: carbon in an amount ranging from 0.024 wt % to 0.036 wt %;phosphorus in an amount ranging from 0.008 wt % to 0.012 wt %;silicon in an amount ranging from 0.08 wt % to 0.12 wt %;calcium in an amount ranging from 0.04 wt % to 0.06 wt %;zirconium in an amount ranging from 0.024 wt % to 0.036 wt %;manganese in an amount ranging from 0.08 wt % to 0.12 wt %;sulfur in an amount ranging from 0.008 wt % to 0.012 wt %;molybdenum in an amount ranging from 4 wt % to 5.1 wt %;nickel in an amount ranging from 18 wt % to 19 wt %;cobalt in an amount ranging from 7 wt % to 12 wt %;aluminum in an amount ranging from 0.05 wt % to 0.15 wt %;titanium in an amount ranging from 0.1 wt % to 0.8 wt %; anda balance of iron based on 100 wt % of said stainless steel alloy, wherein the content of iron is more than 0 wt %.

4. The stainless steel alloy according to claim 3, wherein: carbon is in an amount ranging from 0.027 wt % to 0.033 wt %;phosphorus is in an amount ranging from 0.009 wt % to 0.011 wt %;silicon is in an amount ranging from 0.09 wt % to 0.11 wt %;calcium is in an amount ranging from 0.045 wt % to 0.055 wt %;zirconium is in an amount ranging from 0.027 wt % to 0.033 wt %;manganese is in an amount ranging from 0.09 wt % to 0.11 wt %; andsulfur is in an amount ranging from 0.009 wt % to 0.011 wt %, based on 100 wt % of said stainless steel alloy.

5. The stainless steel alloy according to claim 4, wherein: carbon is in an amount ranging from 0.0285 wt to 0.0315 wt %;phosphorus is in an amount ranging from 0.0095 wt % to 0.0105 wt %;silicon is in an amount ranging from 0.095 wt % to 0.105 wt %;calcium is in an amount ranging from 0.0475 wt % to 0.0525 wt %;zirconium is in an amount ranging from 0.0285 wt to 0.0315 wt %;manganese is in an amount ranging from 0.095 wt % to 0.105 wt %; andsulfur is in an amount ranging from 0.0095 wt % to 0.0105 wt %, based on 100 wt % of said stainless steel alloy.