Method for forming a golf club head assembly

Abstract

To provide a method for forming a golf club head assembly.SOLUTION: A golf club head assembly formation step comprises: a step S62 for positioning a face plate on a recess of a club head; a step S66 for welding the face plate to the club head; a step S70 for, after welding, heating the club head and the face plate, to at least a solvus temperature of the face plate for a prescribed period; and a step S74 for, after heating, air cooling the club head and the face plate.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] Cross - reference to related applications This is a non - provisional patent application of U.S. Provisional Patent Application No. 61 / 941,117, filed on Feb. 18, 2014, and further claims the priority of U.S. Patent Application No. 14 / 228,503, filed on Mar. 28, 2014. The entire contents of all of the above are hereby incorporated by reference in their entirety into this specification.

[0002] The present invention relates to a golf club, and more particularly, to a method of forming a golf club head assembly.

Background Art

[0003] Conventional golf club head assemblies include a face plate that is welded to the club head. The face plate has a slightly rounded shape in order to provide a more straight and / or longer flight path for a golf ball, even when the ball is struck off - center with respect to the face plate. The face plate has a bulge dimension, i.e., the curvature from the toe end to the heel end, and a roll dimension, i.e., the curvature from the crown edge to the sole edge.

Summary of the Invention

[0004] Aspects of the present invention will become more apparent by considering the detailed description and the accompanying drawings.

Brief Description of the Drawings

[0005] [Figure 1] Perspective view of the club head and the face plate. [Figure 2] Perspective view of the club head with the face plate removed. [Figure 3] Top view of the club head assembly. [Figure 4] Side cross - sectional view of the club head assembly of FIG. 3 taken along section 4 - 4. [Figure 5]Figure 3 is a side view of the club head assembly. [Figure 6] This is a schematic diagram of the process for forming a golf club head assembly. [Figure 7] This chart shows experimental bulge and roll measurements for faceplates subjected to various heat treatment processes. [Figure 8] This chart shows experimental roll measurements for faceplates with various geometric shapes. [Figure 9] This chart shows experimental bulge and roll measurements for faceplates subjected to various heat treatment processes. [Figure 10] This chart shows durability measurements for faceplates with various material compositions. [Modes for carrying out the invention]

[0006] Before describing embodiments of the present invention in detail, it should be understood that the present invention is not limited in its application to the details of the structure and arrangement of components described in the following description or illustrated in the following drawings. Other embodiments of the present invention are possible and can be practiced or implemented in various ways. It should also be understood that the expressions and terminology used herein are for illustrative purposes only and should not be considered limiting. The use herein of “including,” “comprising,” and “having,” and their variations, means that the items listed thereafter and their equivalents, as well as additional items, are included. All weight percentage (wt%) numbers described below are total weight percentages.

[0007] Figures 1 to 3 show a golf club head 10 and a face plate 14. In one embodiment, the golf club head 10 is formed from a cast material, and the face plate 14 is formed from a rolled material. Furthermore, in the illustrated embodiments, the golf club head 10 is for a metal wood driver; in other embodiments, the golf club head 10 is for a fairway wood; in other embodiments, the golf club head 10 is for a hybrid club; and in other embodiments, the golf club head 10 is for an iron club. The club head 10 may also include a hosel and a hosel transition (shown as 18). For example, the hosel may be located at or near the heel end 34. The hosel may extend from the club head 10 through the hosel transition 18. To form a golf club, the hosel may receive the first end of the shaft 20. The shaft 20 may be fixed to the golf club head 10 by an adhesive bonding process (e.g., epoxy) and / or other suitable bonding processes (e.g., mechanical bonding, soldering, welding, and / or brazing). Furthermore, to complete the golf club, a grip (not shown) may be fixed to the second end of the shaft 20.

[0008] As shown in Figure 2, the club head 10 further includes a recess or opening 22 for receiving the face plate 14. In the illustrated embodiment, the opening 22 includes a lip portion 26 extending around the periphery of the opening 22. The face plate 14 is aligned with the opening and abuts against the lip portion 26. The face plate 14 is fixed to the club head 10 by welding, forming the club head assembly 30. In one embodiment, the welding is a pulsed plasma welding process.

[0009] The faceplate 14 includes a heel end 34 and a toe end 38 opposite the heel end 34. The heel end 34 is positioned near the hosel portion (hosel and hosel transition 18), where the shaft 20 (Figure 1) is connected to the club head assembly 30. The faceplate 14 further includes a crown edge 42 and a sole edge 46 opposite the crown edge 42. The crown edge 42 is positioned adjacent to the upper edge of the club head 10, while the sole edge 46 is positioned adjacent to the lower edge of the club head 10. As shown in Figure 3, the faceplate 14 has a bulge curvature in the direction extending between the heel end 34 and the toe end 38. As shown in Figures 4 and 5, the faceplate 14 also has a roll curvature in the direction extending between the crown edge 42 and the sole edge 46. In one embodiment, the faceplate may have a minimum wall thickness of 1.5 mm, 1.4 mm, 1.3 mm, 1.2 mm, 1.1 mm, 1.0 mm, 0.9 mm, 0.8 mm, 0.7 mm, 0.6 mm, 0.5 mm, and 0.4 mm. In one embodiment, the faceplate may have a minimum wall thickness of 0.7 mm.

[0010] The faceplate 14 is formed from a titanium alloy. In one embodiment, the faceplate 14 is an α-β titanium (α-βTi) alloy. The α-βTi alloy may contain neutral alloying elements such as tin, as well as α-stabilizers such as aluminum and oxygen. The α-βTi alloy may also contain β-stabilizers such as molybdenum, silicon, and vanadium. All numbers described below in terms of weight percentage are total weight percentages (wt%). The total weight percentage of aluminum as an α-stabilizer in the α-βTi alloy may be between 2 wt% and 10 wt%, between 3 wt% and 9 wt%, between 4 wt% and 8 wt%, or between 5 wt% and 7 wt%. The total weight percentage of oxygen as an α-stabilizing element in the α-βTi alloy may be between 0.05 wt% and 0.35 wt%, or between 0.10 wt% and 0.20 wt%. The total weight percentage of molybdenum as a β-stabilizing element in the α-βTi alloy may be between 0.2 wt% and 1.0 wt%, or between 0.6 wt% and 0.8 wt%, or may be trace amounts. The total weight percentage of vanadium as a β-stabilizing element in the α-βTi alloy may be between 1.5 wt% and 7 wt%, or between 3.5 wt% and 4.5 wt%. The total weight percentage of silicon as a β-stabilizing element in the α-βTi alloy may be between 0.01 wt% and 0.10 wt%, or between 0.03 wt% and 0.07 wt%. The α-βTi alloy may be Ti-6Al-4V (or Ti6-4), Ti-9S (or T-9S), Ti-662, Ti-8-1-1, Ti-65K, Ti-6246, or IMI550. The combination of α and β stabilizing elements allows the α-βTi alloy to be heat-treated.

[0011] In one embodiment, after welding the faceplate 14 to the club head 10, the club head 10 and the faceplate 14 may be heated for a predetermined period to the sorbus temperature of the faceplate, to a temperature just above the sorbus temperature, or to a temperature higher than the sorbus temperature. In another embodiment, after welding the faceplate 14 to the club head 10, the club head assembly 30 may be heat-treated for a predetermined period at the α-βTi sorbus temperature, to a temperature just above the α-βTi sorbus temperature, or to a temperature higher than the α-βTi sorbus temperature. In yet another embodiment, after welding the faceplate 14 to the club head 10, the club head assembly 30 may be heat-treated for a predetermined period at the α-βTi sorbus temperature, to a temperature just above the α-βTi sorbus temperature, or to a temperature higher than the α-βTi sorbus temperature. During this step, an inert gas may be pumped into the heating chamber containing the club head assembly 30 to remove all oxygen for a predetermined period as discussed below. When cooling the club head assembly 30 as discussed below, additional inert gas may be pumped back into the chamber, and the club head assembly 30 may be left to cool in the chamber to room temperature.

[0012] As described above, after heating the club head assembly 30 (or the club head 10 and the welded faceplate 14), the club head assembly 30 is cooled to room temperature. In another embodiment, after heat treatment, the club head assembly 30 may be air-cooled to slowly reduce the temperature of the club head assembly. Cooling of the club head assembly 30 may be carried out in an inert gas environment or an uncontained environment (open air). In another embodiment, the club head assembly 30 may be cooled in an inert gas to slowly reduce the temperature of the club head assembly and reduce the opportunity for oxidation. The inert gas may be selected from the group consisting of nitrogen (N), argon (Ar), helium (He), neon (Ne), krypton (Kr), and xenon (Xe), or mixtures thereof. After heating to the α-βTi sorbus temperature, just above the α-βTi sorbus temperature, or above the α-βTi sorbus temperature, the inert gas may be pumped back into a vacuum chamber containing the club assembly 30, ensuring that oxygen is not present to prevent oxidation of the titanium face plate 14 and the club head surface 10.

[0013] As will be understood by those skilled in the art, the solvous temperature of an alloy is the temperature barrier at which smaller constituent molecules dissolve within the overall matrix of the material, resulting in greater fluidity. The solvous temperatures of most α-βTi alloys are verified in scientific literature or information published by material suppliers and are readily available. Where published data is not available, the temperature value can be estimated and experimentally confirmed, as it depends on the chemistry of the material. The solvous temperature of α-βTi may be above 400°C and below 600°C.

[0014] In one embodiment, α-βTi may be Ti6-4 containing 6 wt% aluminum (Al) and 4 wt% vanadium (V), with the remaining alloy composition being titanium and optionally some trace elements. In some embodiments, Ti6-4 contains between 5.5 wt% and 6.75 wt% Al, between 3.5 wt% and 4.5 wt% V, up to 0.08 wt% carbon (C), up to 0.03 wt% silicon (Si), up to 0.3 wt% iron (Fe), up to 0.2 wt% oxygen (O), up to 0.015 wt% tin (Sn), and trace amounts of molybdenum (Mo), with the remaining alloy composition being titanium. In some embodiments, Ti6-4 contains 5.5 wt% to 6.75 wt% Al, 3.5 wt% to 4.5 wt% V, less than 0.08 wt% carbon (C), less than 0.03 wt% silicon (Si), less than 0.3 wt% iron (Fe), less than 0.2 wt% oxygen (O), less than 0.015 wt% tin (Sn), and trace amounts of molybdenum (Mo), with the remaining alloy composition being titanium. Ti6-4 is Grade 5 titanium. The sorbus temperature of Ti6-4 is between 540°C and 560°C. In some embodiments, Ti6-4 has a load of 0.1597 lb / in 3 It has a density of 4.37 g / cc. Furthermore, Ti-6-4 may be designated as T-65K.

[0015] In other embodiments, the face plate 14 of the golf club head 10 may be another α-βTi alloy such as Ti-9S (or T-9S), which contains 8 wt% Al, 1 wt% V, and 0.2 wt% Si, with the remaining alloy composition being titanium and optionally some trace elements. In some embodiments, Ti-9S (or T-9S) contains 6.5 wt% to 8.5 wt% Al, between 1 wt% and 2 wt% V, up to 0.08 wt% C, up to 0.2 wt% Si, up to 0.3 wt% Fe, up to 0.2 wt% O, up to 0.05 wt% N, trace amounts of Mo, and trace amounts of Sn, with the remaining alloy composition being titanium. In some embodiments, Ti-9S (or T-9S) contains 6.5 wt% to 8.5 wt% Al, between 1 wt% and 2 wt% V, less than 0.1 wt% C, up to 0.2 wt% Si, up to 0.4 wt% Fe, up to 0.15 wt% O, less than 0.05 wt% N, trace amounts of Mo, and trace amounts of Sn, with the remaining alloy composition being titanium. In some embodiments, Ti-9S (or T-9S) contains 6.5 wt% to 8.5 wt% Al, between 1 wt% and 2 wt% V, less than 0.1 wt% C, less than 0.2 wt% Si, less than 0.4 wt% Fe, less than 0.15 wt% O, less than 0.05 wt% N, trace amounts of Mo, and trace amounts of Sn, with the remaining alloy composition being titanium. The sorbus temperature of Ti-9S (or T-9S) is between 560°C and 590°C. In some embodiments, Ti-9S (or T-9S) will have a higher porosity and a lower yield value than Ti8-1-1. Ti-9S (or T-9S) has a yield of approximately 0.156 lb / in 3 From 0.157 lb / in 3 It has a density of (4.32~4.35 g / cc). Ti-9S (or T-9S) has a density of 0.156 lb / in 3 It has a density of 4.32 g / cc.

[0016] In other embodiments, the material may be another α-βTi alloy such as Ti-6-6-2, Ti-6246, or IMI550. Titanium 662 may contain 6 wt% Al, 6 wt% V, and 2 wt% Sn, with the remaining alloy composition being titanium and optionally some trace elements. Ti-6-6-2 has a density of 0.164 lb / in 3 It has a density of (4.54 g / cc). The sorbus temperature of Ti662 is between 540°C and 560°C. Titanium 6246 may contain 6 wt% Al, 2 wt% Sn, 4 wt% zirconium (Zr), and 6 wt% Mo, with the remaining alloy composition being titanium and optionally some trace elements. The sorbus temperature of Ti6246 is between 570°C and 590°C. Ti-6246 has a density of 0.168 lb / in 3 It has a density of 4.65 g / cc. IMI550 may contain 6 wt% Al, 2 wt% Sn, 4 wt% Mo, and 0.5 wt% Si, with the remaining alloy composition being titanium and optionally some trace elements. The sorbus temperature of IMI550 is between 490°C and 510°C. IMI550 has a density of 0.157 lb / in 3 It has a density of 4.60 g / cc.

[0017] In other embodiments, the material can be another α-βTi alloy such as Ti-8-1-1, which may contain 8 wt% Al, 1.0 wt% Mo, and 1 wt% V, with the remaining alloy composition being titanium and optionally some trace elements. In some embodiments, Ti-8-1-1 may contain 7.5 wt% to 8.5 wt% Al, 0.75 wt% to 1.25 wt% Mo, 0.75 wt% to 1.25 wt% V, up to 0.08 wt% C, up to 0.3 wt% Fe, up to 0.12 wt% O, up to 0.05 wt% N, up to 0.015 wt% H, up to 0.015 wt% Sn, and trace amounts of Si, with the remaining alloy composition being titanium. The sorbus temperature of Ti-8-1-1 is between 560°C and 590°C. In some embodiments, Ti-8-1-1 is 0.1580 lb / in 3It has a density of (4.37 g / cc).

[0018] Figure 6 shows a process for forming the club head assembly 30. In a first step 62, the face plate 14 is aligned with the club head 10. A second step 66 includes welding the face plate 14 to the club head 10. In a third step 70, the club head 10 and the face plate 14 are heated to the solvus temperature of the face plate 14 material or above. Finally, in a fourth step 74, the club head 10 and the face plate 14 are air cooled.

[0019] In one embodiment, the club head assembly 30 is heat treated in a third step 70 for between 1 hour and 6 hours at or above the solvus temperature of the α-β Ti alloy. In one embodiment, the club head assembly 30 is heat treated in a third step 70 for between 1 hour and 2 hours at or above the solvus temperature of the α-β Ti alloy. In one embodiment, the club head assembly 30 is heat treated in a third step 70 for between 1 hour and 4 hours at or above the solvus temperature of the α-β Ti alloy. In one embodiment, the club head assembly 30 is heat treated in a third step 70 for between 4 hours and 6 hours at or above the solvus temperature of the α-β Ti alloy. In one embodiment, the club head assembly 30 is heat treated in a third step 70 for between 1.5 hours and 5.5 hours at or above the solvus temperature of the α-β Ti alloy. In one embodiment, the club head assembly 30 is heat treated in a third step 70 for between 2 hours and 5 hours at or above the solvus temperature of the α-β Ti alloy. In one embodiment, the club head assembly 30 is heat treated in a third step 70 for between 2.5 hours and 4.5 hours at or above the solvus temperature of the α-β Ti alloy. In one embodiment, the club head assembly 30 is heat treated in a third step 70 for between 3 hours and 4 hours at or above the solvus temperature of the α-β Ti alloy.

[0020] In one embodiment, the club head assembly 30 is heat-treated in the third step 70 at the sorbus temperature of the α-βTi alloy or a higher temperature for at least 1 hour. In one embodiment, the club head assembly 30 is heat-treated in the third step 70 at the sorbus temperature of the α-βTi alloy or a higher temperature for at least 1.5 hours. In one embodiment, the club head assembly 30 is heat-treated in the third step 70 at the sorbus temperature of the α-βTi alloy or a higher temperature for at least 2 hours. In one embodiment, the club head assembly 30 is heat-treated in the third step 70 at the sorbus temperature of the α-βTi alloy or a higher temperature for at least 2.5 hours. In one embodiment, the club head assembly 30 is heat-treated in the third step 70 at the sorbus temperature of the α-βTi alloy or a higher temperature for at least 3 hours. In one embodiment, the club head assembly 30 is heat-treated in the third step 70 at the sorbus temperature of the α-βTi alloy or a higher temperature for at least 3.5 hours. In one embodiment, the club head assembly 30 is heat-treated in the third step 70 at the sorbus temperature of the α-βTi alloy or a higher temperature for at least 4 hours. In one embodiment, the club head assembly 30 is heat-treated in the third step 70 at the sorbus temperature of the α-βTi alloy or a higher temperature for at least 4.5 hours. In one embodiment, the club head assembly 30 is heat-treated in the third step 70 at the sorbus temperature of the α-βTi alloy or a higher temperature for at least 5 hours. In one embodiment, the club head assembly 30 is heat-treated in the third step 70 at the sorbus temperature of the α-βTi alloy or a higher temperature for at least 5.5 hours.In one embodiment, the club head assembly 30 is heat-treated in the third step 70 at or above the sorbus temperature of the α-βTi alloy for at least 6 hours.

[0021] In one embodiment, the club head assembly 30 is heat-treated between 400°C and 630°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated between 425°C and 550°C. In one embodiment, the club head assembly 30 is heat-treated between 450°C and 525°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated between 550°C and 625°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated in the third step 70 at 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, or 630°C for 30 minutes, 60 minutes, 90 minutes, 120 minutes, 150 minutes, 180 minutes, 210 minutes, 240 minutes, 270 minutes, 300 minutes, 330 minutes, or 360 minutes.

[0022] In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 400°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 420°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 440°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 460°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 475°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 480°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 500°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 520°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 540°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 560°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 575°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 580°C. In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 600°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 620°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 625°C in the third step 70. In one embodiment, the club head assembly 30 is heat-treated at a temperature of at least 630°C in the third step 70.

[0023] In one embodiment, the club head assembly 30 is heat-treated in the third step 70 at a temperature between 475°C and 500°C for 4 to 6 hours. In another embodiment, the club head is heat-treated in the third step 70 at a temperature between 575°C and 625°C for 1 to 2 hours. In yet another embodiment, the club head is heat-treated at approximately 550°C for 1 to 4 hours. In yet another embodiment, the faceplate 14 may be formed from a different alloy in the third step 70. In yet another embodiment, the heat treatment process may be performed at different temperatures and for different durations. In addition, the heat treatment may be applied to a variety of materials and different welding types.

[0024] Unlike conventional club head metal aging processes that occur at low temperatures, heat-treating the club head assembly 30 over a sorbus temperature after welding the faceplate 14 relieves stress within the faceplate 14 and between the weld and the metal matrix of the club head 10. Post-weld stress relief dissipates stress associated with the weld-metal heat-affected zone (HAZ), or the area around the weld where the material properties have been altered due to the welding process. Due to the completely different mechanical properties between the HAZ and the rest of the metal matrix, the HAZ is more susceptible to cracking and defects. Previous post-weld treatments were performed under a sorbus temperature for short durations. These processes simply aged the metal but did not address the increased stress transmitted to the weld area. Moreover, the faceplate was not sufficiently strong and flattened or lost its curvature relatively quickly. In contrast, heat treatment over a sorbus temperature dissipates stress within the weld metal HAZ. Heat treatment improves the durability of the HAZ by relieving stress. In addition, heat-treating the club head assembly 30 above the Solbus temperature reduces the possibility of titanium-aluminum (Ti3Al) crystal formation along the weld.

[0025] The grain boundaries of the faceplate alloy are aligned to a crown-to-sole orientation before heat treatment. The orientation of the alloy grain boundaries from crown to sole allows for elongation in the same direction. In some embodiments, the grain boundaries of the faceplate α-β titanium (α-βTi) alloy may be aligned to a crown-to-sole orientation before heat treatment. The orientation of the α-βTi alloy grain boundaries from crown to sole allows for elongation in the same direction. In some embodiments, the grain boundaries of the faceplate Ti-6Al-4V (or Ti6-4), Ti-9S (or T-9S), Ti-662, Ti-8-1-1, Ti-65K, Ti-6246, or IMI550 alloy may be aligned to a crown-to-sole orientation before heat treatment. The orientation of the grain boundaries of Ti-6Al-4V (or Ti6-4), Ti-9S (or T-9S), Ti-662, Ti-8-1-1, Ti-65K, Ti-6246, or IMI550 alloys from crown to sole allows for elongation in the same direction.

[0026] Furthermore, the heat treatment improves the strength of the faceplate 14. The improved strength allows the faceplate 14 to be made thinner without sacrificing durability, thereby reducing the club head weight. The reduced weight of the faceplate 14 shifts the center of gravity of the club head assembly 30, allowing additional weight to be added to another configuration of the club to further adjust the center of gravity. Increasing the strength of the faceplate 14 also increases the durability of the faceplate 14, allowing the faceplate 14 to withstand a very large number of impacts from golf balls, and to maintain the slightly curved or rounded shape of the faceplate throughout the life of the club while enduring hundreds or thousands of impacts from golf balls. Thus, the club is more forgiving when the ball is hit off-center. This is because the rounded shape of the faceplate 14 provides a "gear effect" between the ball and the faceplate 14.

[0027] As shown in Figure 7, experiments were conducted to compare the effects of various heat treatment temperatures on the faceplate 14 over 2,000 strokes or ball hits. The faceplate 14 was formed from a Ti-9S (or T-9S) alloy. One clubhead assembly was heated to 400°C, below the sorbus temperature of the Ti-9S (or T-9S) alloy. A second clubhead assembly was heated to 600°C, above the sorbus temperature of the Ti-9S (or T-9S) alloy. The measurement data provided in Figure 7 represent the percentage change in radius of curvature of the bulge and roll dimensions compared to the original radius of curvature. The radius of curvature increases as the faceplate becomes flatter. A clubhead assembly with a faceplate 14 made of Ti-9S treated at 400°C became considerably flatter in both its roll and bulge dimensions within 25 strokes to a golf ball. In contrast, the club head assembly with a Ti-9S faceplate treated at 600°C maintained its curvature much better after 2,000 hits than the first club head assembly. The Ti-9S faceplate treated at 600°C maintained its curvature better after 2,000 hits than the first club head assembly with an untreated Ti-6-4 faceplate 14, maintaining curvature in both roll and bulge dimensions.

[0028] With regard to heat treatment at a sorbus temperature (e.g., 400°C), the Ti3Al particles become more fluid and can precipitate into the α-matrix. Some of the Ti3Al particles accumulate at the grain boundary boundaries, causing the material to age harden. In contrast, with regard to heat treatment above the sorbus temperature (e.g., 600°C), the Ti3Al particles instead dissolve into the α-matrix, relieving stress in the material. This stress relief process allows the club head assembly 30 to withstand the tensile and compressive forces during impact with the golf ball.

[0029] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at the sorbus temperature of Ti-9S (or T-9S) is maintained within 2 wt% of its original bulge curvature and roll curvature after about 25 blows. In another embodiment, a faceplate 14 formed from Ti6-4 and heat-treated at the sorbus temperature of Ti6-4 is maintained within 3 wt% of its original roll curvature and within 8 wt% of its original bulge curvature after about 25 blows.

[0030] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at the sorbus temperature of Ti-9S (or T-9S) is maintained within 8 wt% of its original bulge curvature and roll curvature after about 50 blows. In another embodiment, a faceplate 14 formed from Ti6-4 and heat-treated at the sorbus temperature of Ti6-4 is maintained within 5 wt% of its original roll curvature and within 10 wt% of its original bulge curvature after about 50 blows.

[0031] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at the sorbus temperature of Ti-9S (or T-9S) is maintained within 10 wt% of its original bulge curvature and roll curvature after about 75 blows. In another embodiment, a faceplate 14 formed from Ti6-4 and heat-treated at the sorbus temperature of Ti6-4 is maintained within 13 wt% of its original roll curvature and within 10 wt% of its original bulge curvature after about 75 blows.

[0032] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at the sorbus temperature of Ti-9S (or T-9S) is maintained within 10 wt% of its original bulge curvature and roll curvature after about 100 blows. In another embodiment, a faceplate 14 formed from Ti6-4 and heat-treated at the sorbus temperature of Ti6-4 is maintained within 14 wt% of its original roll curvature and within 10 wt% of its original bulge curvature after about 100 blows.

[0033] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at the sorbus temperature of Ti-9S (or T-9S) is maintained within 10 wt% of its original bulge curvature and roll curvature after about 150 blows. In another embodiment, a faceplate 14 formed from Ti6-4 and heat-treated at the sorbus temperature of Ti6-4 is maintained within 15 wt% of its original roll curvature and within 11 wt% of its original bulge curvature after about 150 blows.

[0034] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at the sorbus temperature of Ti-9S (or T-9S) is maintained within 10 wt% of its original bulge curvature and roll curvature after about 300 blows. In another embodiment, a faceplate 14 formed from Ti6-4 and heat-treated at the sorbus temperature of Ti6-4 is maintained within 15 wt% of its original roll curvature and bulge curvature after about 300 blows.

[0035] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at the sorbus temperature of Ti-9S (or T-9S) is maintained within 10 wt% of its original bulge curvature and roll curvature after about 1,000 blows. In another embodiment, a faceplate 14 formed from Ti6-4 and heat-treated at the sorbus temperature of Ti6-4 is maintained within 23 wt% of its original roll curvature and within 17 wt% of its original bulge curvature after about 1,000 blows.

[0036] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at the sorbus temperature of Ti-9S (or T-9S) is maintained within 10 wt% of its original bulge curvature and roll curvature after approximately 2,000 blows. In another embodiment, a faceplate 14 formed from Ti6-4 and heat-treated at the sorbus temperature of Ti6-4 is maintained within 24 wt% of its original roll curvature and within 18 wt% of its original bulge curvature after approximately 2,000 blows.

[0037] Furthermore, experiments were conducted to compare the effects of various heat treatment temperatures on the faceplate 14 over 2,000 strokes or ball impacts. The faceplate 14 was formed from an α-βTi alloy. One clubhead assembly was heated to 400°C, below the sorbus temperature of the α-βTi alloy. A second clubhead assembly was heated to 600°C, above the sorbus temperature of the α-βTi alloy. The clubhead assembly treated at 400°C became very flat in both its roll and bulge dimensions within 25 strokes against a golf ball. In contrast, the clubhead assembly treated at 600°C did not begin to flatten until 225 strokes against a golf ball, and after 2,000 strokes, it maintained its curvature much better than the first clubhead assembly.

[0038] In one embodiment, a club head assembly treated at 600°C maintained its original bulge curvature and roll curvature after 25 strokes. In another embodiment, a club head assembly treated at 600°C maintained its original bulge curvature and roll curvature after 50 strokes. In yet another embodiment, a club head assembly treated at 600°C maintained its original bulge curvature and roll curvature after 75 strokes. In yet another embodiment, a club head assembly treated at 600°C maintained its original bulge curvature and roll curvature after 100 strokes. In yet another embodiment, a club head assembly treated at 600°C maintained its original bulge curvature and roll curvature after 125 strokes. In yet another embodiment, a club head assembly treated at 600°C maintained its original bulge curvature and roll curvature after 150 strokes. In one embodiment, a club head assembly treated at 600°C maintained its original bulge curvature and roll curvature after 175 strokes. In another embodiment, a club head assembly treated at 600°C maintained its original bulge curvature and roll curvature after 200 strokes. In yet another embodiment, a club head assembly treated at 600°C maintained its original bulge curvature and roll curvature after 225 strokes.

[0039] In one embodiment, a club head assembly treated at 600°C substantially maintained its bulge curvature and roll curvature after 250 strokes. In another embodiment, a club head assembly treated at 600°C substantially maintained its bulge curvature and roll curvature after 275 strokes. In yet another embodiment, a club head assembly treated at 600°C substantially maintained its bulge curvature and roll curvature after 300 strokes. In yet another embodiment, a club head assembly treated at 600°C substantially maintained its bulge curvature and roll curvature after 500 strokes. In yet another embodiment, a club head assembly treated at 600°C substantially maintained its bulge curvature and roll curvature after 1,000 strokes. In yet another embodiment, a club head assembly treated at 600°C substantially maintained its bulge curvature and roll curvature after 1,500 strokes. In one embodiment, a club head assembly treated at 600°C substantially maintained its bulge curvature and roll curvature after 2,000 strokes.

[0040] In one embodiment, a club head assembly treated at 600°C maintained its original bulge curvature after 250 strokes, while its roll radius of curvature increased from 11 inches to 13 inches. In another embodiment, a club head assembly treated at 600°C maintained its original bulge curvature and a roll radius of curvature of 13 inches after 275 strokes. In yet another embodiment, a club head assembly treated at 600°C increased its bulge radius of curvature from 12 inches to 13 inches and maintained a roll radius of curvature of 13 inches after 300 strokes. In yet another embodiment, a club head assembly treated at 600°C maintained its bulge radius of curvature of 13 inches and a roll radius of curvature of 13 inches after 500 strokes. In yet another embodiment, a club head assembly treated at 600°C maintained its bulge radius of curvature of 13 inches and increased its roll radius of curvature from 13 inches to 14 inches after 1,000 strokes. In one embodiment, a club head assembly treated at 600°C maintained its bulge radius of curvature of 13 inches and its roll radius of curvature of 14 inches after 1,500 strokes. In another embodiment, a club head assembly treated at 600°C maintained its bulge radius of curvature of 13 inches and its roll radius of curvature of 14 inches after 2,000 strokes.

[0041] Furthermore, as shown in Figure 8, follow-up experiments were conducted to compare the effects of 600°C heat treatment on three different faceplate geometric shapes. Roll measurements for all three faceplate geometric shapes were consistent, confirming that the stress-relaxing heat treatment increased the faceplate's capacity while maintaining its curvature. The faceplates contained Ti-9S (or T-9S) alloy.

[0042] Referring here to Figure 9, experiments were conducted to compare the effects of various heat treatment temperatures on the faceplate 14 over 2,000 blows or ball strikes. The faceplate 14 was formed from a Ti-9S (or T-9S) alloy. One clubhead assembly was heated to 550°C, below the sorbus temperature of the Ti-9S (or T-9S) alloy. A second clubhead assembly was heated to 575°C, and a third clubhead was heated to 600°C, above the sorbus temperature of the Ti-9S (or T-9S) alloy. The measurement data provided in Figure 9 represent the percentage change in radius of curvature of the bulge and roll dimensions compared to the original radius of curvature. The radius of curvature increases as the faceplate becomes flatter. The clubhead assembly treated at 550°C became considerably flatter in both its roll and bulge dimensions within a few blows against a golf ball. In contrast, the club head assembly treated at 600°C maintained its curvature much better after 2,000 hits than the club head assembly treated at 600°C.

[0043] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 600°C is maintained after 25 blows within 1 wt% of its original roll curvature and within 3 wt% of its original bulge curvature. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 575°C is maintained after 25 blows within 24 wt% of its original roll curvature and within 11 wt% of its original bulge curvature. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 550°C is maintained after 25 blows within 19 wt% of its original roll curvature and within 9 wt% of its original bulge curvature.

[0044] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 600°C retains its original roll curvature and is within 4 wt% of its original bulge curvature after 50 blows. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 575°C maintains within 28 wt% of its original roll curvature and within 13 wt% of its original bulge curvature after 50 blows. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 550°C maintains within 23 wt% of its original roll curvature and within 15 wt% of its original bulge curvature after 50 blows.

[0045] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 600°C retains its original roll curvature and is within 5 wt% of its original bulge curvature after 75 blows. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 575°C maintains within 28 wt% of its original roll curvature and within 12 wt% of its original bulge curvature after 75 blows. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 550°C maintains within 28 wt% of its original roll curvature and within 23 wt% of its original bulge curvature after 75 blows.

[0046] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 600°C retains its original roll curvature and is within 6 wt% of its original bulge curvature after 100 blows. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 575°C maintains within 30 wt% of its original roll curvature and within 13 wt% of its original bulge curvature after 100 blows. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 550°C maintains within 29 wt% of its original roll curvature and within 22 wt% of its original bulge curvature after 100 blows.

[0047] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 600°C retains its original roll curvature and is within 7 wt% of its original bulge curvature after 150 blows. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 575°C maintains within 28 wt% of its original roll curvature and within 13 wt% of its original bulge curvature after 150 blows. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 550°C maintains within 31 wt% of its original roll curvature and within 24 wt% of its original bulge curvature after 150 blows.

[0048] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 600°C is maintained after 300 blows within 5 wt% of its original roll curvature and within 5 wt% of its original bulge curvature. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 575°C is maintained after 300 blows within 28 wt% of its original roll curvature and within 14 wt% of its original bulge curvature. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 550°C is maintained after 300 blows within 34 wt% of its original roll curvature and within 26 wt% of its original bulge curvature.

[0049] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 600°C is maintained after 1,000 blows within 4 wt% of its original roll curvature and within 7 wt% of its original bulge curvature. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 575°C is maintained after 1,000 blows within 27 wt% of its original roll curvature and within 13 wt% of its original bulge curvature. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 550°C is maintained after 1,000 blows within 34 wt% of its original roll curvature and within 27 wt% of its original bulge curvature.

[0050] In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 600°C is maintained after 2,000 blows within 5 wt% of its original roll curvature and within 6 wt% of its original bulge curvature. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 575°C is maintained after 2,000 blows within 25 wt% of its original roll curvature and within 15 wt% of its original bulge curvature. In one embodiment, a faceplate 14 formed from Ti-9S (or T-9S) and heat-treated at 550°C is maintained after 2,000 blows within 34 wt% of its original roll curvature and within 28 wt% of its original bulge curvature.

[0051] As shown in Figure 10, experiments were conducted to compare the durability of the faceplate 14 when composed of either a Ti-6-4 alloy or a Ti-9S (T-9S) alloy. The experiments tracked the number of hits from an air cannon until the faceplate 14 broke. One clubhead assembly used a Ti6-4 alloy as the faceplate material. A second clubhead assembly used a different model clubhead with a Ti6-4 alloy as the faceplate material (data not shown). A third clubhead assembly used a third model clubhead with a Ti6-4 alloy as the faceplate material (data not shown). A fourth clubhead assembly used the same model clubhead as the third clubhead assembly, but with a T-9S (or Ti-9S) alloy as the faceplate material. The measurement data provided in Figure 10 represent the number of hits until the faceplate broke. Clubhead assemblies with T-9S (or Ti-9S) alloy faceplates showed increased durability compared to assemblies with Ti6-4 alloy faceplates. The same club head model, with a faceplate made of Ti6-4 alloy, showed an increased durability of approximately 3,200 shots before failure compared to 2,600 shots before failure when using a faceplate made of T-9S (or Ti-9S) alloy.

[0052] Therefore, the present invention provides, in particular, a method for forming a golf club head assembly. While the present invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent embodiments of the present invention as described.

[0053] Clause 1. A method for forming a golf club head assembly, comprising the steps of: providing a face plate formed from an α-β titanium alloy; aligning the face plate with a recess in the club head; welding the face plate to the club head; heating the club head and face plate to a temperature higher than the sorbus temperature of the face plate for a predetermined period of time; and allowing the club head and face plate to cool in an inert gas.

[0054] Clause 2. The method according to Clause 1, wherein the α-β titanium alloy comprises aluminum (Al) between 6.5 wt% and 8.5 wt%, vanadium (V) between 1.0 wt% and 2.0 wt%, oxygen (O) of 0.20 wt% or less, and silicon (Si) of 0.20 wt% or less.

[0055] Clause 3. The α-β titanium alloy as described in Clause 2, further comprising 0.30% or less iron (Fe), 0.08 wt% or less carbon (C), 0.05 wt% or less nitrogen (N), trace amounts of molybdenum (Mo), trace amounts of tin (Sn), and the remaining weight percent being titanium (Ti).

[0056] Clause 4. The step of welding the faceplate is the method according to Clause 1, including a pulsed plasma welding process.

[0057] Clause 5. The method according to Clause 1, which provides a faceplate having a minimum thickness of 0.7 mm.

[0058] Clause 6. The method according to Clause 1, wherein the inert gas in step (e) is selected from the group consisting of nitrogen (N), argon (Ar), helium (He), neon (Ne), krypton (Kr), and xenon (Xe), or mixtures thereof.

[0059] Clause 7. The method according to Clause 6, wherein the inert gas is nitrogen (N) or argon (Ar).

[0060] Clause 8. The method according to Clause 1, wherein the step of heating the club head and faceplate includes the step of heating the club head and faceplate to a temperature between 400°C and 630°C for a period of 1 to 6 hours.

[0061] Clause 9. The method according to Clause 8, wherein the step of heating the club head and faceplate includes heating the club head and faceplate to a temperature between 475°C and 625°C for a period of 1 to 6 hours.

[0062] Clause 10. The method according to Clause 9, wherein the step of heating the club head and faceplate includes heating the club head and faceplate to a temperature between 475°C and 550°C for a period of 4 to 6 hours.

[0063] Clause 11. The method according to Clause 10, wherein the step of heating the club head and faceplate includes heating the club head and faceplate to a temperature between 475°C and 500°C for a period of 4 to 6 hours.

[0064] Clause 12. The method according to Clause 8, wherein the step of heating the club head and faceplate includes heating the club head and faceplate to a temperature between 550°C and 625°C for a period of one to two hours.

[0065] Clause 13. The method according to Clause 12, wherein the step of heating the club head and faceplate includes heating the club head and faceplate to a temperature between 575°C and 625°C for a period of 1 to 2 hours.

[0066] Clause 14. A method for forming a golf club head assembly, comprising the steps of: providing a face plate; aligning the face plate with a recess in a club head; welding the face plate to the club head; heating the club head and face plate to a temperature higher than the sorbus temperature of the face plate for a predetermined period of time after the step of welding the face plate; and allowing the club head and face plate to cool in an inert gas after the step of heating the club head and face plate.

[0067] Clause 15. The faceplate is made of α-β titanium alloy, as described in Clause 14.

[0068] Clause 16. The α-β titanium alloy as described in Clause 15, comprising 6.5 wt% to 8.5 wt% aluminum (Al), 1.0 wt% to 2.0 wt% vanadium (V), 0.20 wt% or less oxygen (O), 0.20 wt% or less silicon (Si), 0.30% or less iron (Fe), 0.08 wt% or less carbon (C), 0.05 wt% or less nitrogen (N), trace molybdenum (Mo), trace tin (Sn), and the remaining weight percent being titanium (Ti).

[0069] Clause 17. The step of welding the faceplate is the method according to Clause 14, including a pulsed plasma welding process.

[0070] Clause 18. The step of heating the club head and faceplate is the method of Clause 14, comprising the step of heating the club head and faceplate for a period of 1 to 6 hours.

[0071] Clause 19. The step of heating the club head and faceplate is the method according to Clause 18, comprising the step of heating the club head and faceplate to a temperature between 400°C and 630°C.

[0072] Clause 20. The method according to Clause 19, wherein the step of heating the club head and faceplate includes heating the club head and faceplate to a temperature between 475°C and 625°C for a period of 1 to 6 hours.

[0073] Clause 21. The method according to Clause 20, wherein the step of heating the club head and faceplate includes heating the club head and faceplate to a temperature between 475°C and 550°C for a period of 4 to 6 hours.

[0074] Clause 22. The method according to Clause 21, wherein the step of heating the club head and faceplate includes heating the club head and faceplate to a temperature between 475°C and 500°C for a period of 4 to 6 hours.

[0075] Clause 23. The method according to Clause 19, wherein the step of heating the club head and faceplate includes heating the club head and faceplate to a temperature between 550°C and 625°C for a period of one to two hours.

[0076] Clause 24. The method according to Clause 23, wherein the step of heating the club head and faceplate includes the step of heating the club head and faceplate to a temperature between 575°C and 625°C for a period of 1 to 2 hours.

[0077] Clause 25. The method according to Clause 14, wherein the inert gas in step (e) is selected from the group consisting of nitrogen (N), argon (Ar), helium (He), neon (Ne), krypton (Kr), and xenon (Xe), or mixtures thereof.

[0078] Clause 26. The method according to Clause 25, wherein the inert gas is nitrogen (N) or argon (Ar).

[0079] Clause 27. A method for forming a golf club head assembly, comprising the steps of (a) providing a face plate formed from an α-β titanium alloy, wherein the α-β titanium alloy comprises aluminum (Al) in an amount between 6.5 wt% and 8.5 wt%, vanadium (V) in an amount between 1.0 wt% and 2.0 wt%, oxygen (O) in an amount of 0.20 wt% or less, and silicon (Si) in an amount of 0.20 wt% or less; (b) aligning the face plate to a recess in the club head; (c) welding the face plate to the club head; (d) heating the club head and the face plate to a temperature higher than the sorbus temperature of the face plate for a predetermined period of time; and (e) allowing the club head and the face plate to cool in an inert gas, wherein step (d) is carried out at a temperature between 525°C and 625°C for an amount of time between 1 hour and 6 hours.

[0080] Clause 28. The α-β titanium alloy as described in Clause 27, further comprising 0.30 wt% or less iron (Fe), 0.08 wt% or less carbon (C), 0.05 wt% or less nitrogen (N), trace amounts of molybdenum (Mo), trace amounts of tin (Sn), and the remaining weight percent being titanium (Ti).

[0081] Clause 29. The welding step of step (c) is the method of Clause 27, which includes a pulsed plasma welding process.

[0082] Clause 30. The method according to Clause 29, wherein the inert gas in step (e) is selected from the group consisting of nitrogen (N), argon (Ar), helium (He), neon (Ne), krypton (Kr), and xenon (Xe), or mixtures thereof.

[0083] Clause 31. The method according to Clause 30, wherein the inert gas is nitrogen (N) or argon (Ar).

[0084] Clause 32. The faceplate of step (a) has a minimum thickness of 0.7 mm, as described in Clause 27.

[0085] Clause 33. The method according to Clause 27, wherein step (d) includes heating the club head and face plate at a temperature between 550°C and 625°C for 1 to 2 hours.

[0086] Clause 34. The method according to Clause 33, wherein the step of heating the club head and faceplate includes the step of heating the club head and faceplate to a temperature between 575°C and 625°C for a period of one to two hours.

[0087] Clause 35. A method for forming a golf club head assembly, comprising the step of providing a face plate formed from an α-β titanium alloy, wherein the α-β titanium alloy comprises aluminum (Al) between 6.5 wt% and 8.5 wt%, vanadium (V) between 1.0 wt% and 2.0 wt%, oxygen (O) less than or equal to 0.20 wt%, silicon (Si) less than or equal to 0.20 wt%, iron (Fe) less than or equal to 0.30 wt%, carbon (C) less than or equal to 0.08 wt%, nitrogen (N) less than or equal to 0.05 wt%, trace molybdenum (Mo), trace tin (Sn), and the remainder by weight. A method comprising the steps of: 1) making a titanium (Ti) faceplate; 2) aligning a faceplate with a recess in a club head; 3) welding the faceplate to the club head; 4) heating the club head and faceplate to a temperature higher than the sorbus temperature of the faceplate for a predetermined period of time after the welding step; and 5) allowing the club head and faceplate to cool in an inert gas environment after the heating step.

[0088] Clause 36. The step of welding the faceplate is the method according to Clause 35, including a pulsed plasma welding process.

[0089] Clause 37. The step of heating the club head and faceplate is the method of Clause 35, comprising the step of heating the club head and faceplate for a period of 1 to 6 hours.

[0090] Clause 38. The step of heating the club head and faceplate is the method according to Clause 37, which includes the step of heating the club head and faceplate to between 400°C and 630°C.

[0091] Clause 39. The step of heating the club head and faceplate is the method of Clause 38, comprising the step of heating the club head and faceplate to a temperature between 475°C and 625°C for a period of 1 to 6 hours.

[0092] Clause 40. The method according to Clause 39, wherein the step of heating the club head and faceplate includes heating the club head and faceplate to a temperature between 475°C and 550°C for a period of 4 to 6 hours.

[0093] Clause 41. The method according to Clause 40, wherein the step of heating the club head and faceplate includes heating the club head and faceplate to a temperature between 475°C and 500°C for a period of 4 to 6 hours.

[0094] Clause 42. The method according to Clause 38, wherein the step of heating the club head and faceplate includes heating the club head and faceplate to a temperature between 550°C and 625°C for a period of one to two hours.

[0095] Clause 43. The method according to Clause 42, wherein the step of heating the club head and faceplate includes heating the club head and faceplate to a temperature between 575°C and 625°C for a period of one to two hours.

[0096] Clause 44. The method according to Clause 35, wherein the inert gas in step (e) is selected from the group consisting of nitrogen (N), argon (Ar), helium (He), neon (Ne), krypton (Kr), and xenon (Xe), or mixtures thereof.

[0097] Clause 45. The method according to Clause 44, wherein the inert gas is nitrogen (N) or argon (Ar).

[0098] Clause 46. The method according to Clause 35, wherein the faceplate of step (a) has a minimum thickness of 0.7 mm.

[0099] Clause 47. A golf club head comprising a crown, a sole, a toe end, a heel end, recesses positioned between the crown and the sole, and between the toe end and the heel end, a hosel positioned adjacent to the heel end, and a face plate aligned with the recess and welded to the club head, wherein the face plate has a bulge curvature extending between the heel end and the toe end, and the face plate comprises an α-β titanium alloy, the α-β titanium alloy comprising 6.5 wt% to 8.5 wt% aluminum (Al), and 1.0 wt% to 2.0 A golf club head containing wt% vanadium (V), less than 0.20 wt% oxygen (O), less than 0.20 wt% silicon (Si), less than 0.30 wt% iron (Fe), less than 0.08 wt% carbon (C), less than 0.05 wt% nitrogen (N), trace amounts of molybdenum (Mo), and trace amounts of tin (Sn), with the remaining weight percent being titanium (Ti), and the club head and face plate being heated between 525°C and 625°C for 1 to 6 hours after the face plate is welded to the club head, and then cooled in an inert gas. Clause 48. The method according to Clause 1, wherein the step of heating the club head and faceplate is carried out at a temperature between 400°C and 625°C for a period of 1 to 6 hours.

Claims

1. A method for forming a golf club head assembly, (a) Providing a faceplate formed from an α-β titanium alloy, wherein the α-β titanium alloy consists of an α-β stabilizing element and titanium, the α-β stabilizing element contains 6.5 wt% to 8.5 wt% aluminum (Al) of the α-β titanium alloy, the α-β titanium alloy further contains 1.0 wt% to 2.0 wt% vanadium (V), 0.30 wt% or less iron (Fe), 0.08 wt% or less carbon (C), 0.05 wt% or less nitrogen (N), 0.2 wt% or less silicon (Si), 0.2 wt% or less oxygen (O), trace amounts of molybdenum (Mo), and trace amounts of tin (Sn), and the remaining weight percent is titanium (Ti), the step of providing, (b) The step of aligning the face plate with the recess of the club head, (c) The step of welding the face plate to the club head, (d) The steps of heating the club head and the face plate to a temperature higher than the Solvas temperature of the face plate for a predetermined period of time, (e) a step of allowing the club head and the face plate to be cooled in an inert gas Includes, The method involves heating at a temperature between 525°C and 1050°C for 1 to 6 hours in step (d).

2. The method according to claim 1, wherein the welding step of step (c) includes a pulsed plasma welding process.

3. The method according to claim 1 or 2, wherein the inert gas in step (e) is selected from the group consisting of nitrogen (N), argon (Ar), helium (He), neon (Ne), krypton (Kr), and xenon (Xe), or a mixture thereof.

4. The method according to claim 3, wherein the inert gas is nitrogen (N) or argon (Ar).

5. The method according to any one of claims 1 to 4, wherein the faceplate in step (a) has a minimum thickness of 0.7 mm.

6. The method according to any one of claims 1 to 5, wherein step (d) includes heating the club head and the face plate at a temperature between 550°C and 1050°C for 1 to 2 hours.

7. The method according to claim 6, wherein the step of heating the club head and the face plate includes heating them at a temperature between 575°C and 1050°C for one to two hours.

8. The method according to any one of claims 1 to 7, wherein step (d) includes heating the club head and the face plate at a temperature between 800°C and 1050°C for one to two hours.

9. It is a golf club head, A faceplate formed from an α-β titanium alloy, wherein the α-β titanium alloy consists of an α-β stabilizing element and titanium, and the α-β stabilizing element contains 6.5 wt% to 8.5 wt% aluminum (Al) of the α-β titanium alloy, comprising the faceplate. The α-β titanium alloy further contains 1 wt% to 2 wt% vanadium (V), 0.30 wt% or less iron (Fe), 0.08 wt% or less carbon (C), 0.05 wt% or less nitrogen (N), 0.2 wt% or less silicon (Si), 0.2 wt% or less oxygen (O), trace amounts of molybdenum (Mo), and trace amounts of tin (Sn), with the remaining weight percentage being titanium (Ti), for a golf club head.

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