GOLF CLUB HEAD ALLOY AND METHOD FOR PRODUCING GOLF CLUB HEAD

Abstract

A golf club head alloy includes 7-8 wt % of aluminium, 2-3 wt % of molybdenum, 1.4-2.0 wt % of chromium, 0.5-1.1 wt % of vanadium, 0.35-1 wt % of silicon, with the balance being titanium and inevitable impurities. A method of using the golf club head alloy to produce a golf club head is also disclosed.

Claims

1. A golf club head alloy comprising 7-8 wt % of aluminum, 2-3 wt % of molybdenum, 1.4-2.0 wt % of chromium, 0.5-1.1 wt % of vanadium, 0.35-1 wt % of silicon, with the balance being titanium and inevitable impurities.

2. The golf club head alloy as claimed in claim 1, wherein the golf club head alloy comprises 2.2-2.8 wt % of molybdenum.

3. The golf club head alloy as claimed in claim 1, wherein a phase tissue of the golf club head after ageing treatment includes 60-80% of α phase, 5-15% of β phase, and 15-26% of Ti.sub.3Al.

4. A method for producing a golf club head, comprising: using the golf club head alloy set forth in claim 1 to produce a golf c lib head; and heating the golf club head for 0.5-1.5 hours at 400-700° C. to carry out an ageing treatment.

5. The method for producing the golf club head as claimed in claim 4, wherein the golf club head is heated for 0.5-1.5 hours at 450-550° C. to carry out the ageing treatment.

6. The method for producing the golf club head as claimed in claim 4, wherein the golf club head after the ageing treatment has a phase tissue including 60-80% of α phase, 5-15% of β phase, and 15-26% of Ti.sub.3Al.

7. A method for producing a golf club head, comprising: using the golf club head alloy set forth in claim 1 to produce a striking plate; welding the striking plate to a club head body to form a golf club head; and heating the golf club head for 0.5-1.5 hours at 400-700° C. to carry out an ageing treatment.

8. The method for producing the golf club head as claimed in claim 7, wherein the golf club head is heated for 0.5-1.5 hours at 450-550° C. to carry out the ageing treatment.

9. The method for producing the golf club head as claimed in claim 7, wherein the golf club head after the ageing treatment has a phase tissue including 60-80% of α phase, 5-15% of β phase, and 15-26% of Ti.sub.3Al.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0017] A preferred embodiment of a golf club head alloy according to the present invention includes 7-8 wt % of aluminum (Al), 2-3 wt % of molybdenum (Mo), 1.4-2.0 wt % of chromium (Cr), 0.5-1.1 wt % of vanadium (V), 0.35-1 wt % of silicon (Si), with the balance being titanium (Ti) and inevitable impurities. The golf club head alloy may include 2.2-2.8 wt % of molybdenum. Furthermore, the inevitable impurities may include at least one of tungsten (W), tin (Say), oxygen (O), niobium (Nb), Tantalum (Ta), nickel (Ni), cobalt (Co), Manganese (Mn), and zirconium (Zr).

[0018] Specifically, chromium, silicon, molybdenum, and vanadium provide the golf club head alloy with a predetermined strength. Furthermore, molybdenum and vanadium provide the golf club head alloy with better plasticity to benefit subsequent casting process, Furthermore, molybdenum and vanadium can avoid segregation while casting the golf club head alloy. 100181 The molybdenum equivalent [Mo].sub.eq and the aluminum equivalent [l].sub.eq affect the composition of α phase and β phase in the golf club head alloy. The molybdenum equivalent and the aluminum equivalent refer to different metal elements that can generate the same effects of molybdenum and aluminum. As shown by the following equation conducted at a certain multiplier, when an alloy includes elements capable of producing the same effect as molybdenum or aluminum, the weight percentage of each element is multiplied by the certain multiplier to obtain a product, and the total effect that can achieved by the molybdenum or aluminum in the alloy is the sum of the products. The molybdenum equivalent of the golf club head is shown in Equation 1.

[Mo].sub.eq=1Mo+-1 25V+0.59W+0.28b+0.22Ta+1 9:3Fe+1.84Cr+1.5Cu+2. 46Ni+2.67Co+2.26Mn+0.3Sn+0.47Zr+3.01Si-1.47Al   Equation 1:

[0019] The aluminum equivalent of the golf club head is shown in Equation 2.

[Al].sub.eq=1Al+1/3Sn+1/6Zr   Equation 2:

[0020] By adjusting the composition proportion of the golf club head alloy, the golf club head alloy may have desired predetermined molybdenum equivalent and desired predetermined aluminum equivalent. In this embodiment, the molybdenum equivalent of the golf club head alloy ranges from −6.20 to −1.38, and the aluminum equivalent of the golf club head alloy ranges from 7.7 to 8.7. The molybdenum equivalent and the aluminum equivalent can increase β phase of the golf club head alloy to form α+β phase. Thus, golf club heads of high yield strength can be produced from the golf club head alloy, providing golf club heads with excellent strength.

[0021] To prove the golf club heads produced from the golf club head alloy indeed have excellent strength, tests are conducted on golf club heads (group 1) produced from current Ti-72S alloy and golf club heads (group 2) produced from the golf club head alloy according to the present invention (see Table 1). The mechanical properties of the golf club heads after ageing treatment for one hour at an ageing temperature of 600° C. are shown in Table 2.

TABLE-US-00001 TABLE 1 composition proportion of golf club head alloy of each group in tests group Al Mo V Cr Si O N Fe Ti 1 7.25 — — — 0.14 0.13 0.01 1.83 Bal 2 7.41 2.54 0.76 1.62 0.35 0.13 0.02 — Bal

TABLE-US-00002 TABLE 2 mechanical properties of alloy of each group tensile strength yield strength Young's modulus group (ksi) (ksi) (Gpa) 1 155-175 145-165 110-130 2 176-185 170-180 110-130

[0022] According to the above test results, the tensile strength and yield strength of the golf club heads produced from the golf club head alloy according to the present invention are higher than those of the golf club heads produced from Ti-72S. This shows that the golf club heads produced from the golf club head alloy according to the present invention indeed have high strength.

[0023] It is noted that an alloy in the solid state has two isomers: α phase at room temperature and β phase at high temperature. A phase change between α phase and β phase occurs during a temperature increasing procedure of the alloy. When heat treatment is conducted on the alloy at a predetermined ageing temperature, a second phase other than α phase and β phase can be precipitated. The second phase is a general term for any phase other than α phase and β phase. Presence of the second phase is helpful in increasing the yield strength to thereby increase the hardness of material, which is called “precipitation hardening.” By observing the phase tissue heated at an ageing temperature of 600° C., the golf club head alloy includes 70-90% of α phase, 5-15% of β phase, and 10-26% of Ti.sub.3Al phase. Furthermore, as can be seen from the phase tissue heated at an ageing temperature of 500° C., the golf club head alloy includes 60-80% of α phase, 545% of β phase, and 15-26% Ti.sub.3Al phase. Thus, the golf club head can have better yield strength and excellent hardness through precipitation of 10-25% of Ti.sub.3Al phase, Furthermore, observation of the proportion of the phase tissues (formed at the ageing temperature of 600° C. and 500° C.) of examples of Ti-72s and the golf club head alloy of an embodiment according to the present invention is conducted to observe precipitation of the second phase, and the results are shown in Table 3.

TABLE-US-00003 TABLE 3 phase proportion of alloy of each group group phase type proportion group 1 ageing α 90.1%  temperature 600° C. β 9.4% Ti.sub.5Si.sub.3 0.5% group 2 ageing α 78.2%  temperature 600° C. β .sup. 9% Ti.sub.3Al 11.4%  Ti.sub.5Si.sub.3 .sup. 1% Laves 0.4% group 2 aging α 66.0%  temperature 500° C. β 5.2% Ti.sub.3Al 25.9%  Ti.sub.5Si.sub.3 1.1% Laves 1.8%

[0024] According to the above results, the precipitated second phase of conventional golf club bead alloy Ti-72S (group 1) is only 0.5% (Ti.sub.5Si.sub.3), whereas the precipitated second phase of the golf club head alloy according to the present invention includes 12.8-28.8% (Ti.sub.3Al, Ti.sub.5Si.sub.3, and Laves phase). This shows that the golf club head alloy according to the present invention can precipitate more amount of second phase and, thus, have high strength, Furthermore, partial irregular arrangement of the atoms in the alloy crystal causes dislocation movement of the crystal lattice (so-called “dislocation”). The dislocation is deemed as a deficiency in alloy and will cause deformation of metal, The metal can be hardened if the dislocation can be avoided. Thus, the golf club head alloy according to the present invention has better strength. Namely, the composition of the golf club head alloy according to the present invention can also avoid dislocation to reduce generation of deficiencies in the alloy. In comparison with conventional Ti-72S alloy, the golf club head produced from the golf club head alloy according to the present invention may have better mechanical properties (tensile strength and yield strength) and may avoid the produced golf club head from segregation and dislocation, thereby improving the quality of the golf club head produced from the golf club head alloy.

[0025] For example, the golf club head alloy according to the present invention can be used to produce a golf club head or a part of the golf club head, which is not limited in this invention. In this embodiment, the golf club head alloy is used to produce a striking plate of a golf club head. The golf club head alloy can be used to produce a striking plate of a predetermined shape according to the type and model of the club head. Then, the striking plate is welded to a chub head body to form the golf club head. The golf club head is heated at 400-700° C. for 0.5-1.5 hours to conduct an ageing treatment. Preferably, the golf club head is heated at 450-550° C. for 0.5-1.5 hours to conduct an ageing treatment. Thus, the mechanical properties and the plasticity of the striking plate are changed. As a result, the striking plate has a tensile strength of 176-200 ksi, a yield strength of170-190 ksi and a density of 4.39-4.43 g/cm.sup.3. These mechanical properties are excellent, Furthermore, the striking plate is welded to the club head body prior to the ageing treatment to avoid a change in the size of the striking plate that might prohibit welding of the striking plate to the club head body.

TABLE-US-00004 TABLE 4 mechanical properties obtained from different ageing temperatures Ageing Tensile strength Yield strength Young's Modulus temperature (ksi) (ksi) (Gpa) 600° C. 176-185 170-180 110-130 500° C. 186-200 181-190 131-150

[0026] Furthermore, the mechanical properties of an example (group 2 in Table 1) according to the present invention after ageing treatments respectively at 500° C. and 600° C. are measured, and the results are shown in Table 3. The mechanical properties of the golf club head obtained through ageing treatment at 500° C. are better than those of the golf club head obtained through ageing treatment at 600° C.

[0027] In view of the foregoing, in the golf club head alloy according to the present invention, more amount of second phase can be precipitated through the composition proportion of aluminum, molybdenum, chromium, vanadium, and silicon. Thus, the golf club head alloy is better in tensile strength, yield strength, and hardness. As a result, the golf club head produced from the golf club head alloy has better strength. Furthermore, by the composition of the golf chub head alloy according to the present invention (such as replacing iron in current golf club head alloy with chromium and including molybdenum and vanadium), non-uniform arrangement of atoms in the alloy crystal is avoided, thereby avoiding deficiencies of segregation and dislocation. This is helpful in increasing the strength of the golf club head alloy, such that the golf club head (or its striking plate) produced from the golf club head alloy is less likely to deform or break during hitting, thereby improving the quality of the golf club head. Furthermore, when the golf club head alloy according to the present invention is used to produce a golf club head, the golf club head produced avoided from deficiencies, and high-strength golf club heads can be produced, increasing the yield of golf club heads.

[0028] Although the present invention has been described with respect to the above preferred embodiments, these embodiments are not intended to restrict the present invention. Various changes and modifications on the above embodiments made by any person skilled in the art without departing from the spirit and scope of the present invention are still within the technical category protected by the present invention. Accordingly, the scope of the present invention should be defined by the appended claims.