JP2003003224A - High-strength titanium alloy material, method of manufacturing for the same and golf club head using the alloy material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a fatique resistance characteristic. SOLUTION: This high-strength titanium alloy material consists of the titanium alloy expressed by the composition formula, Ti100-x-y M1xM2y (all the numerical values are atomic %), where M1 is one or >=2 kinds of the elements selected from Zr and Hf; M2 is one or >=2 kinds of the elements selected from V, Nb, Ta, Mo, Cr and W and x+y<=50 (0<x<50, 0<y<50). This material is constituted by subjecting the alloy to cold rolling after hot forging and is used for at least a portion of a head 1.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a high-strength titanium alloy material capable of improving fatigue resistance, a method for producing the same, and a golf club head using the alloy material.

[0002]

2. Description of the Related Art For example, in a wood type golf club head, in order to increase the flight distance of a hit ball, it is preferable to use a metal material having a high resilience for the face portion hitting the ball. Has been done. In recent years, Ti-15M has been used as a metal material with excellent resilience.
β-type titanium alloys such as o-3Cr-3Sn-3Al are being widely used.

However, in recent years, it has been desired to improve the strength of the face member, in particular, to improve the fatigue strength which influences the durability of the head, due to the thinning of the face portion and the improvement of the golfer's head speed accompanying the improvement of golf equipment. Be done.

The present invention has been made in view of the above problems, and is basically formed by using a titanium alloy having a constant composition and performing hot forging and then cold rolling. It is an object of the present invention to provide a high-strength titanium alloy material capable of further improving strength and fatigue resistance and a method for producing the same. Further, the invention according to claim 5 aims to provide a golf club head which is useful for improving durability, based on the fact that the alloy material is used for at least a part of the face portion.

[0005]

The invention according to claim 1 of the present invention comprises a titanium alloy represented by the following compositional formula and is formed by hot forging and then cold rolling. It is a high strength titanium alloy material. Ti100-xy M1x M2y (all numerical values are atomic%) where M1 is one or more elements selected from Zr and Hf, and M2 is V, Nb, Ta, Mo, Cr, W
One or more elements selected from, and x + y ≦ 5
0 (0 <x <50, 0 <y <50).

The invention according to claim 2 is the rolled high-strength titanium alloy material according to claim 1, wherein the hot forging process has a thickness reduction rate of 10% or more.

The invention according to claim 3 is the high-strength titanium alloy rolled material according to claim 1 or 2, wherein the cold rolling process has a rolling reduction of 10% or more.

The invention according to claim 4 is a step of hot forging a titanium alloy represented by the following composition formula, and a step of cold rolling a raw material obtained by this hot forging. And a method of manufacturing a high-strength titanium alloy material. Ti100-xy M1x M2y (all numerical values are atomic%) where M1 is one or more elements selected from Zr and Hf, and M2 is V, Nb, Ta, Mo, Cr, W
One or more elements selected from, and x + y ≦ 5
0 (0 <x <50, 0 <y <50).

According to a fifth aspect of the present invention, there is provided a golf club head in which the high-strength titanium alloy material according to the first to third aspects is used for at least a part of a face portion for hitting a ball. is there.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the case where the high strength titanium alloy material of the present invention is used for a face member of a golf club head will be described as an example with reference to the drawings. FIG. 1 is a front view of a golf club head (hereinafter, may be simply referred to as “head”) 1 of the present embodiment, FIG. 2 is an end view taken along the line YY, and FIG.
2A and 2B are perspective views each showing a face member as a single body, and FIGS. 1 and 2 each show a reference state in which the head 1 is placed on the horizontal plane HP at a specified lie angle α and loft angle β.

In the figure, a head 1 according to the present embodiment has a face portion 2 for hitting a ball, a crown portion 3 which is continuous with the upper edge 2a of the face portion 2 and constitutes the upper surface of the head, and a lower edge 2b of the face portion 2. The sole portion 4 which is continuous with the bottom portion and forms the bottom surface of the head, the side portion 5 which extends between the crown portion 3 and the sole portion 4 from the toe 2t of the face portion 2 to the heel 2h through the back face, and a shaft (not shown) are attached. And a shaft mounting portion 6. Further, the head 1 of the present embodiment is exemplified by a wood type head made of a metal material and having a hollow inside.

The head 1 has a plate-shaped face member 7 which is at least a part of the face portion 2, which is a main portion in this example, and a main body portion 9 having an opening for arranging the face member 7 on the ball striking face side. An example is one formed by integrally fixing and. In FIG. 1, the boundary of the face member 7 is shown by a chain line, and the total surface area S of the face portion 2 is S.
1 and the surface area S2 of the face member 7 (S2 / S1)
Is preferably set to, for example, 0.9 or more.

The body portion 9 is formed by appropriately welding one member or two or more members, and a titanium alloy is preferably used. In this example, the head body 9 is α +
As the β type titanium alloy, Ti-6Al-4V integrally formed by lost wax casting will be exemplified. Further, the shaft mounting portion 6 is formed so as to project upward in this example, and a shaft mounting hole 6a into which a shaft (not shown) can be inserted and fixed by an adhesive agent or the like is formed therein. Since the hole center line CL of the shaft attachment hole 6a substantially coincides with the axial center line of the shaft to be attached later, in this specification, the lie angle α is defined with reference to the hole center line CL.

For the face member 7, a high strength titanium alloy material made of a titanium alloy represented by the following composition formula (1) and formed by hot forging and cold rolling is used. Has been. Ti100-xy M1x M2y (all numerical values are atomic%) (1) where M1 is one or more elements selected from Zr and Hf, and M2 is V, Nb, Ta, Mo, Cr, W
One or more elements selected from, and x + y ≦ 5
0 (0 <x <50, 0 <y <50).

As a result of the experiments conducted by the present inventors, the titanium alloy represented by the above formula (1) has a large Young's modulus and a large elastic elongation and a large plastic elongation while having a large tensile strength and hardness. For the sake of showing, it has been found that it is suitable for a face member having high resilience. The high strength and hardness of such a titanium alloy are mainly due to solid solution strengthening due to solid solution of elements having a large atomic radius difference, for example, an atomic radius difference of 10% or more from the above combination, and a low Young's modulus. Is that the constituent elements do not have an attractive interaction with each other, so that atoms can move reversibly at low stress. Furthermore, the large elastic elongation limit is due to the variety of reversible transfer sites due to many kinds of elements that have no interaction. It is believed that this is because reversible atom transfer can occur up to a high strain region due to the property, and the increase of deformation stress is less likely to occur.

Particularly, by solid-dissolving the constituent elements containing at least two elements having a large difference in atomic radius as described above, rearrangement of atoms becomes difficult to occur and the diffusivity is lowered. Therefore, for example, quenching the molten metal. Even if it is slowly cooled, a β-type titanium alloy mainly containing the bcc solid solution single phase or the bcc solid solution can be obtained. By subjecting such a solid solution to hot forging, mechanical strength is improved and hardness is stabilized so that the strength level of the base material can be improved and the ductility can be improved. Further, by cold rolling the raw material obtained by hot forging, work hardening is caused and higher strength can be imparted more effectively.

In the above formula (1), when the titanium content is less than 50 atomic%, excellent mechanical properties of the alloy described above can be exhibited, but the specific gravity tends to increase, so that the head has When applied, it tends to increase weight, cost, and melting point. Further, when the element of Zr or Hf is not contained, it tends to be difficult to form a solid solution with a large amount of metal elements having a large difference in atomic radius, and solid solution strengthening tends to be impossible. On the other hand, if the total content of Zr and Hf elements exceeds 50 atomic%, there are problems that the specific gravity increases and the melting point increases. Furthermore, when one or two elements selected from V, Nb, Ta, Mo, Cr and W are not contained, the strength and the corrosion resistance are likely to decrease. On the other hand, if the total content of these elements exceeds 50 atomic%, the specific gravity of the alloy becomes large, the melting point becomes high, and the cost tends to increase. Particularly preferred is a combination of Ti, Zr, Nb and Ta. That is, let M1 be Zr and M2
Are Nb and Ta. Zr is more preferably 10
It is desirable to set the content to ˜40 at%, more preferably 15 to 30 at%, and the balance should be composed substantially of Nb and Ta.

In the present embodiment, the titanium alloy represented by the above formula (1) is first hot forged. The hot forging can reduce the force required for processing and can bring the shape of the face member close to the finished face member, so that the formability of the face member 7 can be improved. In hot forging, voids existing inside the titanium alloy can be compressed by forging, which improves quality such as densification of crystal structure, reduction of internal defects, and uniformization of segregation, which is useful for improving fatigue resistance. Furthermore, by hot forging, titanium alloy suppresses variations in mechanical properties such as tensile strength and hardness, and grain flows along the product shape are obtained, improving toughness and further improving fatigue resistance. It also helps to improve.

The hot forging is a molding method in which a lump-shaped material (billet) is heated to a temperature higher than the recrystallization temperature and hit or pressed to be molded into a predetermined shape. It does not include so-called rolling in which the raw material is caught in the roll and stretched. The forging temperature T, which is the heating temperature of the material during forging, is preferably 600 to 2000.
C., more preferably 700 to 1500.degree. C. is desirable. Since the melting point of the titanium alloy represented by the above formula (1) tends to be relatively high, the forging temperature T is 600.
If the temperature is less than ℃, composition flow of the material is difficult to occur and workability deteriorates, so that a high-power forging device is required, and cracks and cracks tend to occur during processing. On the other hand, if the forging temperature T exceeds 2000 ° C., high-power forging equipment is required, which tends to increase the manufacturing cost and easily causes material deterioration.

Further, the forming method in forging includes various ones such as free forging, die forging (including open die, closed die or semi-enclosed die), high speed forging or isothermal forging, and the material undergoes compression plastic deformation. Any appropriate material can be adopted as long as it can. Preferably, it is desirable to use a closed die forging method or the like in which an oxide film (scale) is less likely to occur on the surface of the blank obtained by forging.

In the hot forging step, a raw material a such as a billet having a prismatic shape (however, a cylindrical shape and other shapes may be used) as shown in FIG. 4 is prepared. Then, after heating this material a to a predetermined temperature, it is forged by a forging machine to obtain a raw material. In hot forging, the deformation resistance of the material is smaller than that in cold rolling, so the thickness reduction rate represented by the following formula (2) is 10% or more, more preferably 40 to 90%, and further preferably It is desirable to raise it to about 75 to 85%. Thickness reduction rate = {(h1-h2) / h1} × 100 [%] (2) (where h1 is the maximum thickness of the material before forging, and h2 is the thickness after forging)

If the thickness reduction rate during hot forging is less than 10%, the composition flow is small and the mechanical properties such as bending strength and fatigue strength cannot be improved by forging, which is not preferable. On the other hand, if the rate of decrease in thickness is too large, cracks may occur during forging, and it is necessary to raise the forging temperature in order to prevent cracks.
This is not preferable because it tends to increase equipment costs and processing costs.

The hot forging process is performed at the forging temperature T
It is desirable that the ratio (T / R) of (° C.) to the thickness reduction rate R (%) is 10 or more, more preferably 15 or more, and further preferably 20 or more. If the ratio (T / R) is less than 10, the forging temperature becomes low with respect to the thickness reduction rate,
Workability tends to deteriorate and cracks and the like tend to occur.
The upper limit of the ratio (T / R) is not particularly limited, but if it is too large, the forging temperature will be excessively increased with respect to the thickness reduction rate, and there is a problem in practical use. 100 or less in combination with the lower limit of
It is more preferably set to 75 or less, and further preferably set to 50 or less.

In the hot forging step, it is possible to perform forging in a plurality of stages by changing the processing tools such as roughing and finishing. When an oxide film is formed on the surface of the face member after hot forging, the oxide film is removed by polishing the surface of the blank b.

Next, the raw material b obtained by hot forging is
It is cooled to room temperature and cold-rolled. The raw material b whose mechanical strength is improved and hardness is stabilized by hot forging is rolled by cold rolling,
A large number of dislocations and other lattice defects are introduced into the material, and mechanical strength and fatigue resistance can be further improved.

In the rolling process, for example, as shown in FIG. 4C, the raw material b obtained by hot forging is frictionally caught between a pair of rotating rolls R, R, and is cut without thickening. This is a process that reduces the area. In addition, cold rolling is performed by rolling at room temperature without intentionally heating the material, and is distinguished from warm or hot rolling in which the material is heated and rolled. Specifically, as cold rolling, -20 to 100 ° C, more preferably 0 to 100, in consideration of the ambient temperature and the heat generated by the material during rolling.
It is desirable to process at a temperature of 15 ° C, more preferably 15-100 ° C. This temperature means the material temperature during processing.

When the temperature during the cold rolling process exceeds 100 ° C., rearrangement and recrystallization of dislocations in the crystal of the material occur, work hardening cannot be fully expected, and eventually mechanical strength is improved. And the improvement of fatigue resistance cannot be fully expected, and conversely -20
If the temperature is lower than 0 ° C, cracks and the like are likely to occur on the side edges of the rolled rolled material at right angles to the rolling direction, and the yield of the material tends to deteriorate. Further, in the cold rolling process, the deformation resistance of the material is larger than that in the hot rolling process, so the rolling reduction (thickness reduction amount) in one rolling process is, for example, about 0.1 to 0.5 mm, It is preferable to form the rolled material 10 having a desired thickness by repeating this a plurality of times. In this embodiment, a rolled material (high-strength titanium alloy material) 10 having a thickness of about 3 mm is prepared.

On the other hand, if the reduction ratio in cold working is too small, the dislocation density of the titanium alloy cannot be increased, and the effect of improving the mechanical strength by work hardening becomes low. For this reason,
Preferably, the rolling reduction is 10% or more, more preferably 30% or more, and further preferably 50% or more. On the other hand, if the rolling reduction is too large, there is no particular problem from the viewpoint of improving the strength of the material, but since large processing equipment is required, practically, 90% or less in combination with any of the above lower limits, Preferably 85
% Or less, and particularly preferably 80% or less. By thus controlling the rolling reduction during cold rolling, the tensile strength can be further improved by work hardening while maintaining the low Young's modulus of the titanium alloy.
The rolling reduction is calculated by the following formula: rolling reduction = {(h2−h3) / h2} × 100 [%], where h2 is the thickness before rolling and h3 is the thickness after rolling.

As a result of various experiments conducted by the inventors, it is desirable that the reduction ratio E (%) during the cold rolling process and the thickness reduction ratio R (%) during the hot forging process satisfy the following expressions. I knew that. (1-R / 100) × (1-E / 100) ≦ 0.55 If the value on the left side of the above equation exceeds 0.55, the thickness reduction rate R and / or the rolling reduction E becomes small, so In some cases, the improvement of the mechanical strength may not be sufficiently obtained. More preferably, the value on the left side of the above formula is 0.50 or less, and even more preferably 0.
It is preferably 40 or less. The lower limit of the value on the left side is not particularly limited, but is preferably 0.10 or more, more preferably 0.15 or more.

In the cold rolling process, the rolling direction K
Although a single direction (shown in FIG. 4C) may be used, rolling is preferably performed in two or more kinds of directions intersecting with each other. That is, since the rolling direction and the direction perpendicular to the rolling direction have different strengths against bending, the anisotropy such as the mechanical strength of the material can be increased by using two or more kinds that intersect the rolling direction. It is preferable to reduce it as much as possible.
The crossing angle of the rolling direction is preferably 40 to 90 °.

The face member 7 can be obtained by punching the rolled material 10 thus obtained into a predetermined shape. Further, the face member 7 is subjected to press working if necessary, and is given a curvature such as a face roll or a face bulge. At this time, it is desirable that the press working is performed at a temperature of 400 ° C. or lower. When the temperature during pressing exceeds 400 ° C, new strain-free crystal grains nucleate in the titanium alloy, which grows by eating the regions with high dislocations, and eventually the new crystal grains completely cover the material. This is because the mechanical strength and fatigue resistance of the titanium alloy, which have been enhanced by the cold rolling, are lost. More preferably, the temperature at the time of press working is 350 ° C. or lower, more preferably 300 ° C. or lower, further preferably 200 ° C. or lower, particularly preferably 100 ° C. or lower, and further preferably at room temperature. The mechanical strength of can be maintained.

Regarding the lower limit temperature during press working,
Although not particularly limited, if the temperature is extremely low, the toughness is impaired, so in combination with any value of the upper limit temperature, for example, -20 ° C or higher, preferably 0 ° C or higher, more preferably 15 ° C or higher, Particularly preferably 20
It is desirable to set the temperature above ℃. Note that this temperature is the temperature of the rolled material 10.

The thickness t (shown in FIG. 2) of the finished face member 7 is not particularly limited, but is, for example, 1.0 to 4.0 mm, more preferably 2.0 to 3.0 mm.
More preferably, the thickness t is 2.2 to 2.7 mm. When the thickness t is less than 1.0 mm, the practical strength tends to be insufficient and the durability tends to decrease, and conversely 4.
If it exceeds 0 mm, the rigidity of the face part 2 will be excessively increased,
The resilience performance tends to decrease, and the flight distance of a hit ball tends to decrease.

The face member 7 made of titanium alloy thus obtained has a maximum bending stress (JI).
SZ2204) is preferably 1700 MPa or more, more preferably 1800 MPa or more, and particularly preferably 1900 MPa or more. Such bending maximum stress can be increased by increasing the thickness reduction rate R during hot forging or the reduction rate E during cold rolling.

Even if the maximum bending stress is large, the absolute thickness t of the face member 7 is small, and conversely, even if the thickness t of the face member 7 is large, the maximum bending stress is extremely low. In each case, the practical strength of the head 1 tends to be insufficient. From this point of view, the maximum bending stress k of the face member 7 and the thickness t of the face member 7 are
The value of the product k x t (MPa · mm) is 4300 to 700
0, more preferably 4500 to 7000, and particularly preferably 4800 to 7000 is desirable.

Face member 7 molded as described above
Is fixed to the ball striking face side of the main body portion 9 by a fixing means such as adhesion, caulking, welding, pressure welding, brazing or the like to form the head 1.

FIG. 5 shows another embodiment of the present invention.
In FIG. 4, the hot-forged raw material b has a substantially uniform thickness, but as shown in FIG. 5A, in the hot forging process, the thin-walled portion b1 and the thick-walled portion b2 are formed. It is also possible to form a blank b having a uniform thickness and having a thickness. As shown in FIG. 5 (B), such a raw material b is cold-rolled to have a uniform thickness, for example, so that the thin portion b1 is formed.
It is possible to obtain a rolled material 10 having a small rolling reduction and a large rolling reduction at the thick portion b2 (needless to say, it is not necessary to roll to a uniform thickness).

In such a rolled material 10, the high rolling portion 10a having a large reduction rate is the low rolling portion 10 having a small reduction rate.
It is harder and has a higher bending strength than b. Therefore, it is desirable to use the high-rolled portion 10a in the central region including the sweet spot of the face portion 2 which often has a direct contact with the golf ball. On the other hand, low rolling section 1
0b is softer and easier to bend than the high rolling portion 10a.
Therefore, by disposing the low rolling portion 10b on the outside of the high rolling portion 10a in the face portion 2, both high strength and improvement in resilience performance can be achieved. Moreover, such a head 1
Is also preferable in that the feel at impact can be softened and the feel at impact can be improved. Although not shown, a similar rolled material 10 can be manufactured by rolling a raw material that has been hot forged to a uniform thickness to have a non-uniform thickness.

The embodiment of the present invention has been described above by taking the wood type golf club head as an example.
It is needless to say that the present invention is not limited to wood type golf club heads, and can be suitably applied to iron type, putter type and utility type heads.

[0040]

EXAMPLES Next, examples of the present invention will be described more specifically. (Example 1) A titanium alloy satisfying the above formula (1) having a composition of "Ti50Zr30Nb10Ta10" (atomic radius difference is minimum-maximum of about 11.7%) was manufactured by the following method. First, the constituent elements are melted in a vacuum arc melting furnace in an atmosphere that is evacuated and replaced with argon, and the molten metal having the above composition is cooled by a mold to form a rectangular ingot (width 70 mm).
X length 70 mm x thickness 10 mm) was obtained. Then, this ingot was preheated to 1000 ° C. and hot-die forged by a 350 ton crank type press machine to obtain a plate-shaped raw material having a thickness of 7 mm (thickness reduction rate R = 30%). Next, in order to remove the oxide film formed on both sides of this base material, it was ground by a milling machine to a thickness of 6 mm and cold-rolled at room temperature (23 ° C) to obtain a rolled material with a thickness of 3 mm ( The rolling reduction E = 50%) was obtained (the total thickness reduction rate corresponds to 67%).

(Examples 2 to 4) The same ingot was manufactured in the same process by changing the thickness reduction rate R and the reduction rate E.

Comparative Example 1 A plate material having the same composition as in Example 1 and having a thickness of 10 mm was heated to room temperature (23 ° C.) without heating.
Cold rolled with a plate-shaped rolled material with a thickness of 3.3 mm (reduction ratio E =
67%), and both sides of this rolled material were polished to obtain a plate material having a thickness of 3 mm.

(Comparative Example 2) A plate material having the same composition as in Example 1 and having a thickness of 10 mm was heated to 1000 ° C. and hot-rolled, and a plate-shaped rolled material having a thickness of 3.3 mm (reduction ratio E = 67%)
While molding, rolled both sides of this rolled material to a thickness of 3
A plate material of mm was obtained.

(Comparative Example 3) A plate material having the same composition as in Example 1 and having a thickness of 10 mm was heated to 1000 ° C. and hot forged to obtain a plate-shaped raw material having a thickness of 3.3 mm (thickness reduction). Rate R = 67
%), And both sides of this rolled material were polished to obtain a plate material having a thickness of 3 mm. The test method is as follows.

<Fatigue resistance test (bending fatigue test)> A strip-shaped test piece having a width of 20 mm, a length of 50 mm and a thickness of 3 mm was cut out from each test material, and one end of the test piece was fixed and the other end had a frequency of 2 Hz. A bending load varying along a sin curve having an amplitude of 350 MPa (700 MPa at peak to peak) was applied and the number of loads (1 cycle was counted once) until the test piece was broken was measured. It is shown that the fatigue resistance is more excellent as the number of times of loading is increased.

<Bending maximum stress (bending test)> In order to examine the mechanical strength of each test material, JIS Z2204 was used.
No. 3 test piece was manufactured in accordance with the above, and a bending test was performed to measure the bending maximum stress (n = 3).

<Elastic Elongation (Yield Elongation)> JISZ220
No. 5 test piece was prepared from each of the above plate materials in accordance with No. 1 (n =
3), using a tensile tester conforming to JIS B7721
A tensile test based on Z2241 was performed. Table 1 shows the test results and the like.

[0048]

[Table 1]

As is clear from Comparative Example 1 and Comparative Example 2, hot rolling improves the ductility (elastic elongation) of the material as compared with cold rolling, but on the other hand, bending maximum stress and fatigue resistance It can be seen that Further, in Comparative Example 3 in which hot forging processing was performed, maximum bending stress, elastic elongation,
Both fatigue resistance characteristics are improved. Furthermore, Examples 1 to 1
As shown in No. 3, in the case of performing cold rolling after hot forging, the fatigue resistance and the maximum bending stress were significantly improved as compared with Comparative Example 3 without substantially impairing the elastic elongation. You can confirm that it has been realized. When such a high strength titanium alloy material is used for a face member of a golf club head, it is useful for providing a golf club head having excellent durability. It can also be confirmed that in the examples, the durability and the maximum bending stress are improved as the thickness reduction rate and the rolling reduction increase. Further, since the Young's modulus does not substantially change, it is possible to prevent a problem such as a reduction in the resilience performance of the head.

[0050]

As described above, the high-strength titanium alloy material according to claim 1 is made of a titanium alloy represented by a specific composition formula, and is formed by hot forging and then cold rolling. As a result, mechanical strength, especially fatigue resistance, can be significantly improved.

When the thickness reduction rate in the hot forging process or the rolling reduction rate in the cold rolling process is limited to a certain range as in the second to third aspects of the present invention, cracks in the forging and rolling processes occur. It is possible to realize higher fatigue resistance while preventing the occurrence of cracks, and to improve the quality or yield of the alloy material.

According to the invention of claim 4, it is possible to easily manufacture a high-strength titanium alloy material capable of greatly improving mechanical strength, especially fatigue resistance.

According to the invention of claim 5, a high strength titanium alloy material is used for at least a part of the face portion of the golf club head to provide a golf club head having excellent durability. Further, as a result of being able to secure a large elastic elongation, it is also possible to prevent reduction of the resilience performance, which is useful for increasing flight distance.

[Brief description of drawings]

FIG. 1 is a front view of a golf club head of a present embodiment in a standard state.

FIG. 2 is an end view of the Y-Y line.

FIG. 3 is a perspective view showing an example of a face member.

4A is a schematic diagram showing an ingot, FIG. 4B is a raw material obtained by hot forging the ingot, and FIG. 4C is a schematic diagram showing a rolled material.

5A and 5B are schematic diagrams showing, as another embodiment of the present invention, FIG. 5A is a raw material having a non-uniform thickness obtained by hot forging, and FIG.

[Explanation of symbols]

1 golf club head 2 face part 3 Crown 4 sole part 5 side parts 6 Shaft mounting part 7 Face member

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B21J 13/02 B21J 13/02 B B21K 17/00 B21K 17/00 C22F 1/18 C22F 1/18 H / / C22F 1/00 630 1/00 630A 630G 673 673 682 682 683 683 685 685 685Z 694 694A F term (reference) 2C002 AA02 AA03 MM04 PP02 PP03 SS02 4E087 BA05 CB01 CB03 HA88

Claims (5)

[Claims] 1. A high-strength titanium alloy material comprising a titanium alloy represented by the following composition formula and formed by hot forging and then cold rolling. Ti100-xy M1x M2y (all numerical values are atomic%) where M1 is one or more elements selected from Zr and Hf, M2 is 1 selected from V, Nb, Ta, Mo, Cr and W Or two or more elements, and x + y ≦ 50 (0 <x <
50, 0 <y <50). 2. The hot forging process has a thickness reduction rate of 10%.
The high-strength titanium alloy rolled material according to claim 1, which is the above. 3. The high-strength titanium alloy rolled material according to claim 1, wherein the cold rolling process has a rolling reduction of 10% or more. 4. A hot-forging process of a titanium alloy represented by the following composition formula, and a cold-rolling process of a blank obtained by the hot-forging process. Method for producing high strength titanium alloy material. Ti100-xy M1x M2y (all numerical values are atomic%) where M1 is one or more elements selected from Zr and Hf, M2 is 1 selected from V, Nb, Ta, Mo, Cr and W Or two or more elements, and x + y ≦ 50 (0 <x <
50, 0 <y <50). 5. A golf club head, wherein the high-strength titanium alloy material according to any one of claims 1 to 3 is used for at least a part of a face portion for hitting a ball.