JP2002000776A - Maraging steel plate for golf club head and golf club head using the steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a maraging steel plate for a golf club head having excellent vibration isolation characteristics and a golf club head using the steel plate. SOLUTION: The maraging steel sheet of the present invention has a chemical composition in which Ni: 15 to 19% and Co: 8 to 15 by mass%.
%, Mo: 4 to 7%, Ti: 0.2 to 1.8% and the balance substantially Fe as essential components, and one of the Ti segregation ratio and the Mo segregation ratio in the plate thickness direction is 1.
3 or more, and both the Ti segregation ratio and the Mo segregation ratio are 2.5 or less. In the golf club head 1 of the present invention, a face portion 4 having a hitting surface S is formed on a head main body 2, and at least the face portion 4 is formed of the maraging steel plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a maraging steel plate for a golf club head having a sufficient strength and an excellent ability to absorb a shock when hit, and a golf club head having a face portion formed of the steel plate.

[0002]

2. Description of the Related Art The progress of golf club materials has been remarkable. The flight distance of the golf ball has been further improved by improving the material strength, specific strength, elongation, moment of inertia, head capacity, etc. of the metal golf club head together with the improvement of the material of the golf club shaft. Metal golf club heads are roughly classified into wood club heads and iron club heads. Conventionally, wood club heads include martensitic stainless steel (for example, JIS SUS630 stainless steel), titanium alloy (for example,
6Al-4V titanium alloy) and the like, and the iron club head is made of mild steel, martensitic stainless steel,
Austenitic stainless steel (for example, JIS standard S
US 304 stainless steel) or the like.

However, conventional metal golf club heads have various drawbacks because the strength of the metal material used as the head material is low. For example, there is a problem that the thickness of the face portion of the golf club head must be set thick to withstand a high impact force at the time of hitting. If the thickness of the face portion is increased, the center of gravity of the head cannot be made deeper toward the rear side, so that the directional stability of the hit ball decreases. In addition, it is necessary to increase the thickness of each part of the head in order to secure the strength, and there is a problem that the weight of the head increases.

[0004] In order to overcome the above drawbacks, Japanese Patent No. 2789 is disclosed.
As disclosed in JP-A-304, JP-A-7-308410, JP-A-8-89604, etc., the face portion of the head can be formed of a Ni-based maraging steel sheet having excellent tensile strength. It is being done.

[0005]

The weight of the head, especially the weight of the face portion, has been reduced by forming the face portion and the like of the metal golf club head from the maraging steel plate. In addition, the flight distance of the golf ball hit by the face portion is improved.

However, since the maraging steel sheet is inferior in anti-vibration properties, the impact at the time of hitting is transmitted directly to the golfer's arm, and the feel of hitting feels hard.

The present invention has been made in view of such a problem, and provides a maraging steel sheet for a golf club head having excellent vibration isolation characteristics, and a golf club head using the steel sheet.

[0008] Japanese Utility Model Registration No. 3029832 discloses that a clad material in which a tough metal layer and a soft metal layer are alternately joined in a laminating manner on a face portion of a golf club head is used. Has resilience,
Moreover, it is described that a soft shot feeling can be obtained. However, when the face portion is formed of the clad material, even if the hard tough metal layer of the clad material is formed of maraging steel, since the soft metal layer has low strength, the face portion is required to obtain the same strength. Is inevitably thicker than in the case of forming maraging steel alone, which is against weight reduction. Further, when the clad material is used, there is a problem that the production cost is higher than when the maraging steel material is used alone.

[0009]

According to the maraging steel sheet of the present invention, the chemical composition is as follows: Ni: 15 to 19% by mass%;
o: 8 to 15%, Mo: 3 to 7%, Ti: 0.2 to 1.
8% and the balance substantially Fe as an essential component, one of the Ti segregation ratio and the Mo segregation ratio in the thickness direction is 1.3 or more, and the Ti segregation ratio and Mo
Each of the segregation ratios was set to 2.5 or less.

As other chemical components of the maraging steel sheet, C: 0.015% or less, Si: 0.04% or less,
Mn: 0.04% or less, P: 0.008% or less, S:
0.005% or less, Al: 0.01 to 0.2%, N:
0.008% or less. In addition, the maraging steel sheet is subjected to an aging treatment, whereby an intermetallic compound is finely precipitated, and high strength can be achieved.

Further, in the golf club head according to the present invention, a face portion having a hitting surface is formed on the head body, and at least the face portion is formed of the maraging steel plate.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have studied the segregation of components of a maraging steel sheet and found that Mo, T
It has been found that by appropriately segregating i in a laminated state, it is possible to improve the shock absorbing ability from the hardness difference caused by segregation without impairing the strength, ductility and toughness, and have completed the present invention. That is, in the maraging steel sheet of the present invention, the chemical components are Ni: 15 to 19%, Co: 8 to 15%, Mo: 3 to 7%, Ti: 0.2 to 1.8% by mass%, and the balance. Substantially contains Fe as an essential component, and either the Ti segregation ratio or the Mo segregation ratio in the thickness direction is 1.3 or more, and both the Ti segregation ratio and the Mo segregation ratio are 2.5 or less. It is said that. The component segregation ratio of Ti and Mo refers to Ti,
The ratio of the maximum density to the minimum density of Mo (maximum density / minimum density).

First, the reasons for limiting the chemical components will be described. Ni: 15 to 19% Ni is an indispensable element for forming a matrix structure having a high toughness, and a content of 15% or more is required to achieve a tensile strength of 1600 MPa or more. But,
If it exceeds 19%, a martensitic single phase structure cannot be obtained,
The strength is reduced. Therefore, 15-19
%, Preferably 17 to 18.5%.

Co: 8 to 15% Co promotes precipitation of an intermetallic compound containing Mo, but when the content exceeds 15%, toughness is reduced. Also, 8%
If it is less than 10, the strength is reduced. Therefore, it is set to 8 to 15%. Preferably it is 8 to 12%.

Mo: 3 to 7% Mo is an element that precipitates intermetallic compounds of Fe ₂ Mo and Ni ₃ Mo by aging treatment and is effective for strengthening steel. However, if the content is less than 3%, the reinforcement becomes insufficient, and
%, Microsegregation in steel increases, and the toughness decreases. Therefore, the content is 3 to 7%, preferably 4 to 5%.

Ti: 0.2-1.8% Ti is an element effective for strengthening steel like Mo by precipitating an intermetallic compound of Ni ₃ Ti by aging treatment. However, if the content is less than 0.2%, the reinforcement is insufficient, and if it exceeds 1.8%, the micro segregation in the steel increases remarkably, and the toughness is reduced. In addition, Ti (C, N) -based nonmetallic inclusions increase and deteriorate durability. Therefore, the content is set to 0.2 to 1.8%, preferably 0.5 to 1.2%.

[0017] The maraging steel sheet of the present invention contains, in addition to the above components, the balance of Fe as an essential component.
An appropriate element can be added as long as the effect is not hindered. For example, the following elements can be contained in the described range.

C: 0.015% or less C forms carbides, and the amount of precipitation of intermetallic compounds is reduced to lower the tensile strength.
It is good to keep it at 0.015% or less, preferably 0.010% or less.

Si: 0.04% or less Since Si forms nonmetallic inclusions such as SiO ₂ and reduces ductility and toughness, the smaller the amount of Si, the better.
%.

Mn: 0.04% or less Mn forms nonmetallic inclusions such as MnO ₂ and reduces ductility and toughness. Therefore, the smaller the amount of Mn, the better.
%.

P: not more than 0.008% P decreases ductility and toughness due to grain boundary embrittlement and formation of nonmetallic inclusions, so it is desirable that P be as small as possible, and 0.008% or less, preferably 0.005% or less. , More preferably 0.
It is better to keep it below 002%.

S: 0.005% or less S reduces ductility and toughness due to grain boundary embrittlement and formation of nonmetallic inclusions.
%.

Al: 0.01 to 0.2% Al is added for deoxidation, but if it is less than 0.01%, deoxidation becomes insufficient, and if it exceeds 0.2%, alumina-based oxides increase. Therefore, it is preferable to limit the amount to 0.2% or less because the durability is reduced.

N: 0.008% or less N is a harmful element that adversely affects ductility and toughness.
It is important to reduce the content to 8% or less, and if it exceeds 0.008%, mainly the TiN sharply increases and moreover, it becomes a dot array, so that the ductility and toughness are remarkably reduced. TiN
In order to completely suppress the adverse effect of N, it is desirable to limit N to 0.003% or less.

Next, the M of the maraging steel sheet of the present invention
The reasons for limiting the component segregation ratio of o and Ti will be described.

In the maraging steel sheet of the present invention, Mo,
Ti is an element that is easily segregated, and the intermetallic compound increases in a portion where these elements are segregated, and the hardness increases in comparison with a non-segregated portion. That is, in the maraging steel sheet, segregated portions, that is, hard portions, and unsegregated portions, that is, soft portions are alternately formed in layers in the thickness direction in a microscopic view. For this reason, the impact absorbing ability can be improved without reducing the strength, ductility, and toughness in the direction parallel to the plate surface. When the degree of segregation of Mo and Ti is expressed by using a component segregation ratio, as is clear from the examples described later, when both of the component segregation ratios of Ti and Mo are less than 1.3, the shock absorbing ability is reduced. Become like Therefore, in the present invention, one of the component segregation ratios of Ti and Mo is set to 1.3 or more, preferably 1.4 or more, more preferably 1.5 or more. On the other hand, if any of the component segregation ratios of Ti and Mo exceeds 2.5,
Since the boundary between the high hardness portion segregated at a high concentration of Ti or Mo and the soft portion not segregated becomes a base point of fracture, ductility and toughness are reduced. On the other hand, when the segregation ratio exceeds 3.0, retained austenite is generated in a portion where segregation has a high concentration, and the strength is rather reduced. Therefore,
In the present invention, each of the segregation ratios of Ti and Mo is limited to 2.5 or less, preferably 2.2 or less.

[0027] The maraging steel sheet of the present invention melts the steel having the chemical composition, preferably in a vacuum atmosphere.
The molten steel is cast, the resulting ingot is hot forged, and then subjected to a soaking treatment (homogenization heat treatment) if necessary, and then hot-rolled and cast to a desired thickness. It is manufactured by further performing cold rolling as needed.

The component segregation ratio of Ti or Mo in the thickness direction of the maraging steel sheet is as follows: forging ratio in hot forging (cross-sectional area before forging / cross-sectional area after forging), processing temperature in soaking processing, and processing temperature. It can be adjusted by controlling the time (total holding time at the processing temperature). In order to secure the component segregation ratio of Ti and Mo according to the present invention, the forging ratio in the hot forging of the steel ingot is set to about 3 or more, and the soaking process is not performed, or the processing temperature is lower than 1200 ° C. , Preferably 1
It is recommended to perform the treatment at a temperature of 150 ° C. or less and a treatment time of about 100 hr or less, preferably about 24 hr or less. It should be noted that the segregation ratio of Ti and Mo in the forged piece after the soaking treatment hardly changes even if plastic working such as rolling is performed thereafter, and the substantially same segregation ratio is maintained.

In the production of a normal maraging steel sheet, if the component segregation generated at the time of casting is not removed by hot working or heat treatment, a band structure is generated and the ductility in the direction perpendicular to the rolling direction and the ductility are reduced. Since toughness is reduced, it is desired that component segregation is small. For this reason, as the soaking treatment conditions, usually, the treatment temperature is 1200 ° C. or more, and the treatment time is 10 to 20 hours. However, if the sheet thickness is 5 mm or less, the reduction in ductility and toughness in the direction perpendicular to the rolling direction or in the sheet thickness direction can be almost ignored.

The maraging steel sheet of the present invention is formed into a desired shape, subjected to a solution treatment if necessary, and then subjected to an aging treatment to increase the strength. The solution treatment is a heat treatment for heating the austenite region for homogenization, for example, at a temperature of about 750 to 900 ° C. for about 1 to 5 hours, preferably at a temperature of about 780 to 830 ° C. for about 30 min to 2 hours. I do. The aging treatment is a heat treatment for improving the strength by finely depositing an intermetallic compound. For example, the aging treatment is performed at a temperature of about 400 to 550 ° C. for one hour.
The temperature is maintained for about 10 to 10 hours, preferably about 480 to 520 ° C. for about 2 to 5 hours.

The maraging steel sheet of the present invention is suitably used for a face portion of a golf club head. FIG.
1 shows an iron club head 1 and a head body 2 having a neck portion 3 to which a shaft is attached formed at an end portion.
A face portion 4 formed of the maraging steel plate of the present invention is attached to the front surface of the head. On the other hand, FIG. 2 shows a wood club head 11, in which a face portion 14 made of a maraging steel plate of the present invention is provided on the front surface of a hollow shell-shaped head body 12 having a neck portion 13 formed at an end. It is attached. The front surfaces of the face portions 4 and 14 have a hitting surface S. It goes without saying that the maraging steel sheet of the present invention can be applied to the face portion of the putter club head in addition to the club heads 1 and 11. The club heads 1 and 11 are assembled by welding a head body member made of, for example, stainless steel and a face member formed of a maraging steel plate of the present invention,
It is manufactured by performing solution treatment and aging treatment. In the case of the wood club head 11, the head body 1
2 can also be formed by the maraging steel sheet of the present invention. In this case, the head body member is appropriately divided,
Each of the divided parts can be assembled by welding. The golf club head according to the present invention includes not only a finished product subjected to the solution treatment and the aging treatment but also a semi-finished product before performing these treatments.

Next, the present invention will be specifically described with reference to examples, but the present invention is not construed as being limited to such examples.

[0033]

EXAMPLE A steel having the chemical composition shown in Table 1 below was melted by a vacuum induction melting method, and a cast piece (500 kgf) of the melted steel was hot forged in accordance with the manufacturing conditions shown in Table 2 to obtain a forged piece. And then hot rolling and cold rolling were performed to obtain cold-rolled steel sheets having a thickness of 2 mm and 4 mm.

From a cold-rolled steel sheet having a thickness of 2 mm, a test piece material for measuring vibration isolation characteristics having a length of 60 mm and a width of 10 mm was sampled along the rolling direction. Further, a tensile test specimen material having a parallel portion of φ3.3 mm and a length of 20 mm was sampled from a cold-rolled steel sheet having a thickness of 4 mm along the rolling direction. 820 ° C-1h for these test piece materials
The solution treatment of r and the aging treatment at 480 ° C. for 4 hours were performed to obtain a test piece for measuring vibration damping properties and a tensile test piece.

Using the test piece for measuring the vibration isolation characteristics, a high-temperature elastic modulus measuring device (manufactured by Nippon Techno Plus Co., Ltd.) for measuring the elastic modulus based on the natural vibration resonance method at room temperature torsional vibration damping rate (internal wear, Q ^-1 ) was measured.
Further, a tensile test was performed using the tensile test piece, and the tensile strength and the draw ratio were determined. On the other hand, the plate thickness 2mm
A test piece for measuring the segregation ratio was collected from the cold-rolled steel sheet, and thereby the component segregation ratio of Ti and Mo in the thickness direction was determined. The component segregation ratio is determined by EPMA in the thickness direction of the test piece.
The distributions of the Ti concentration and the Mo concentration in the thickness direction were obtained by performing a line analysis with, and were calculated from the maximum value / minimum value using the maximum value and the minimum value. FIG. 3 is a graph showing an example of the concentration distribution of the segregation component in the thickness direction (Ti concentration distribution of Sample No. 3 in Table 2). Table 2 also shows the results of these measurements.

[0036]

[Table 1]

[0037]

[Table 2]

From Table 2, it can be seen that the examples (Sample Nos. 2, 3, 5-
7, 10, 11), it can be seen that the tensile strength is about 2200 MPa or more, the drawing ratio is 30% or more, and high strength and high ductility and high toughness are provided. Moreover,
Internal wear is about 8.7 × 10 ^-4 or more.
It can be seen that it has excellent vibration damping ability and vibration damping ability.
In particular, when the component segregation ratio of Mo and Ti is 1.5 or more, the internal wear is 9.2 × 10 ⁻⁴ or more, and the vibration damping ability and vibration damping ability are excellent.

[0039]

According to the maraging steel sheet of the present invention,
Since Mo and Ti are segregated so as to have a predetermined component segregation ratio in the thickness direction, a hard segregated portion and a soft non-segregated portion are laminated, and the vibration damping property is maintained without deteriorating the strength and toughness. Excellent vibration damping. In addition, the golf club head of the present invention also has excellent vibration proof characteristics because at least the face portion is formed of the maraging steel plate.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a vertical section passing through a face portion of an iron club head according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view of a wood club head according to another embodiment of the present invention in a vertical cross section passing through a face portion.

FIG. 3 is a graph showing an example of a concentration distribution diagram of a segregation component (Ti) in a plate thickness direction in Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Iron club head 11 Wood club head 2,12 Head body 4,14 Face part S

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masami Ueda 2-191-1, Minami Suita, Suita-shi, Osaka Sumitomo Special Metals Co., Ltd. (72) Inventor Akio Hashimoto 2--19 Minami Suita, Suita-shi, Osaka No. 1 Sumitomo Tokushu Metal Co., Ltd. Suita Works F-term (reference) 2C002 AA02 LL01 MM04

Claims (4)

[Claims] 1. The chemical composition is essentially: mass: Ni: 15 to 19%, Co: 8 to 15%, Mo: 3 to 7%, Ti: 0.2 to 1.8%, and the balance substantially Fe. For a golf club head which contains as an active component, one of the Ti segregation ratio and the Mo segregation ratio in the thickness direction is 1.3 or more, and both the Ti segregation ratio and the Mo segregation ratio are 2.5 or less. Maraging steel sheet. 2. Chemical components: C: 0.015% or less, Si: 0.04% or less, Mn: 0.04% or less, P: 0.008% or less, S: 0.005% or less, Al The maraging steel sheet for a golf club head according to claim 1, comprising: 0.01 to 0.2%, and N: 0.008% or less. 3. The maraging steel sheet for a golf club head according to claim 1, which has been subjected to an aging treatment. 4. A golf club head having a face portion having a hitting surface formed on a head body, wherein at least the face portion is any one of claims 1 to 3.
14. A golf club head formed of the maraging steel sheet described in the item 5.