Method for single-step heat treatment of titanium alloys, golf club striking faces, and golf club heads
A method for manufacturing a golf club head includes forming a pre-forged striking face insert from an α-β titanium alloy having a Molybdenum equivalency of about 6 to 12 or an Al equivalency of about 2 to 7, and forging the pre-forged striking face insert into a forged striking face insert having a specified geometry or curvature. In some embodiments, the method may also include performing only a single-step heat treatment on the striking face insert including heating the striking face insert to a temperature below a beta transus temperature of the α-β titanium alloy for a period of time, and thereafter cooling the striking face insert to ambient temperature. In some other embodiments, the method may further include attaching the forged striking face insert to an aft body portion to form a golf club head, and performing the single-step heat treatment and cooling on the golf club head.
1 . A method for manufacturing a striking face insert configured for use in a golf club head, the method comprising:
forming a pre-forged striking face insert from an alpha-beta (α-β) titanium alloy having an Al equivalency as calculated using Equation 2 of about 2 to about 7;
forging the pre-forged striking face insert into a forged striking face insert having a specified geometry or curvature;
performing only a single-step heat-treatment on the forged striking face insert, the single-step heat-treatment comprising heating the forged striking face insert in a heating chamber to a temperature of about 780 C to about 880 C for about 15 to about 45 minutes; and
thereafter cooling the forged striking face insert to ambient temperature,
Al Eq.=( wt % Al)+0.33( wt % Sn)+0.16( wt % Zr)+10[( wt % O)+( wt % C)+2( wt % N)]. Equation 2
2 . The method according to claim 1 , wherein the α-β titanium alloy comprises a Ti—Al—V—Mo—Fe or Ti—Al—V—Fe—Cr alloy and has a Molybdenum equivalency as calculated using Equation 1 of about 6 to about 12:
Mo Eq.=( wt % Mo)+0.2( wt % Ta)+0.28( wt % Nb)+0.4( wt % W)+0.67( wt % V)+1.25( wt % Cr)+1.25( wt % Ni)+1.7( wt % Mn)+1.7( wt % Co)+2.9( wt % Fe). Equation 1
3 . The method according to claim 1 , wherein the forging the pre-forged striking face insert comprises heat exposure of the pre-forged striking face, and deforming the pre-forged striking face insert during or after the heat exposure to form the forged striking face insert having the specified geometry or curvature.
4 . The method according to claim 3 , wherein the heat exposure comprises heating the pre-forged striking face to an exposure temperature below the beta transus temperature of the α-β titanium alloy.
5 . The method according to claim 3 , wherein the heat exposure comprises heating the pre-forged striking face to a temperature of about 740 C to about 780 C.
6 . The method according to claim 1 , wherein the cooling comprises flooding the heating chamber with an inert gas.
7 . The method according to claim 6 , wherein the inert gas comprises argon gas.
8 . The method according to claim 1 , wherein the striking face insert has a Young's Modulus of at least about 100 gigapascals (GPa).
9 . The method according to claim 1 , wherein the striking face insert has a Young's Modulus of about 100 GPa to about 115 GPa.
10 . The method according to claim 1 , wherein the single-step heat-treatment is performed under vacuum.
11 . A method for manufacturing a golf club head, the method comprising:
forming a pre-forged striking face insert from an alpha-beta (α-β) titanium alloy having an Al equivalency as calculated using Equation 2 of about 2 to about 7;
forging the pre-forged striking face insert into a forged striking face insert having a specified geometry or curvature;
attaching the forged striking face insert to an aft body portion to form a golf club head;
performing only a single-step heat-treatment on the golf club head, the single-step heat-treatment comprising heating the golf club head in a heating chamber to a temperature of about 780 C to about 880 C for about 15 to about 45 minutes; and
thereafter cooling the golf club head to ambient temperature:
Al Eq.=( wt % Al)+0.33( wt % Sn)+0.16( wt % Zr)+10[( wt % O)+( wt % C)+2( wt % N)]. Equation 2
12 . The method according to claim 11 , wherein the α-β titanium alloy comprises a Ti—Al—V—Mo—Fe or Ti—Al—V—Fe—Cr alloy and has a Molybdenum equivalency as calculated using Equation 1 of about 6 to about 12:
Mo Eq.=( wt % Mo)+0.2( wt % Ta)+0.28( wt % Nb)+0.4( wt % W)+0.67( wt % V)+1.25( wt % Cr)+1.25( wt % Ni)+1.7( wt % Mn)+1.7( wt % Co)+2.9( wt % Fe). Equation 1
13 . The method according to claim 11 , wherein the forging the pre-forged striking face insert comprises heat exposure of the pre-forged striking face, and deforming the pre-forged striking face insert during or after the heat exposure to form the forged striking face insert having the specified geometry or curvature.
14 . The method according to claim 13 , wherein the heat exposure comprises heating the pre-forged striking face to an exposure temperature below the beta transus temperature of the α-β titanium alloy.
15 . The method according to claim 13 , wherein the heat exposure comprises heating the pre-forged striking face to a temperature of about 740 C to about 780 C.
16 . The method according to claim 11 , wherein the cooling comprises flooding the heating chamber with an inert gas.
17 . The method according to claim 16 , wherein the inert gas comprises argon gas.
18 . The method according to claim 11 , wherein the striking face insert has a Young's Modulus of at least about 100 gigapascals (GPa).
19 . The method according to claim 11 , wherein the striking face insert has a Young's Modulus of about 100 GPa to about 115 GPa.
20 . The method according to claim 11 , wherein the single-step heat-treatment is performed under vacuum.