JP2003129189A - Low density iron-base alloy material for golf club head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low density iron-base alloy material for a golf club head, which can be applied to the club head made especially by casting or forging, has density in a range of 6.1-6.6 g/cm<3> , has a high rust-preventive effect, and can further exhibit an excellent forged surface. SOLUTION: This low density iron-base alloy material comprises 28.0-31.5 wt.% Mn, 7.8-10.0 wt.% Al, 0.90-1.10 wt.% C, 0.35-2.5 wt.% Ti, and the balance Fe, having density of 6.1-6.6 g/cm<3> , and made of its surface roughness to 3 μm or less by hot-forging the above material at 900-1,100 deg.C.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is particularly applicable to a club head made by casting or forging, and has 6.1 to 6.6 g / cm ³
The present invention relates to a low density iron-based alloy material for a golf club head, which has a density in the range of 1, a high rust preventive effect, and can provide an excellent forged surface.

[0002]

2. Description of the Related Art Generally, a golf club set has a wood club, an iron club, a pitching wedge, a sound wedge, a putter, etc., which are club heads,
It consists of a shaft (metal type or carbon resin type), hosel and rubber grip.

Since the rear portion of the wood club head is generally circular and the shaft is relatively long, it is mainly used for the first shot and long distance, and the head of each wood club is used. With different loft angle and shaft length, Driver (No. 1), Brushy (No. 2), Spoon (No. 3), Buffy (No. 4) and Creek (No. 5)
In recent years, numbers 7 and 9 have come to be used depending on individual technique, physical fitness, and taste. Further, the shaft length of the driver is in the range of 43.5 to 46.5 inches, and the loft angle is between 7.0 to 11.5 degrees, and clubs under the driver have the shaft length reduced by 0.5 inches in steps. In addition, the loft angle increases by 3 degrees, and generally, the longer the shaft, the greater the flight distance of the hit ball, and the larger the loft angle, the higher the hit ball.

Persimmon (persimmon tree) was mainly used as the material for the wooden club head.
Metallic materials are being changed in terms of toughness and strength.
Pure titanium and titanium alloy 6-
4, SP-700, 15-3-3-2, 2041, and duplex stainless steel 220
5, stainless steel 17-4PH, AISI431, AISI455, AISI456
And aviation Al-Li alloys and Be-Cu alloys, among which pure titanium, titanium alloys 6-4, SP-700, 15-3-3-
Although 2,2041 is a very expensive material, it has a higher usage ratio than wood due to its excellent material properties.

As described above, there are iron clubs, pitching wedges, sound wedges, and the like as iron clubs, the main purpose of which is to accurately hit the ball to the target point, and the characteristic is the wood club ( Compared to drivers, brassies, spoons, buffies, creeks, etc.), the flight distance is shorter, but the hit ball is high and it is easy to hit in the target direction. Also, the length of the shaft of the 1st iron is about 39.5 inches and the loft angle is 14 degrees. For the 1st iron and below, the length of the shaft is shortened by 0.5 inches and the loft angle is increased by 4 degrees. Thereby, the user calculates the distance to the target and selects and uses an appropriate iron club.

When manufacturing the head portion of the iron club, pitching wedge, and sound wedge, stainless steel-based materials such as AISI455, stainless steel 17-4PH, AISI are used.
431, duplex stainless steel 2205, AISI455, AISI456, Be-Cu
Alloy or forged soft iron is used, but other than that, after forming the head part with titanium alloy 6-4, SP-700, 15-3-3-2, 2041 forged or roller-rolled thin plate, A method of fitting stainless steel 17-4PH, AISI431, duplex stainless steel 2205, AISI455 or AISI456 to the head portion may be adopted.

Further, in recent years, a hollow iron club head having a long distance and accuracy performance which are characteristics of an iron club and a conventional wood club has been developed.

A pitching wedge for a short distance such as near the green and a sound wedge for a bunker are included in an iron club, and both have a heavy head portion and a large loft angle. Therefore, it is easy to raise the flying ball and it is easy to control the ball.

Furthermore, the putter has a striking surface perpendicular to the ground, the purpose of which is to prevent the ball from rising, and the putter provides an excellent striking feel.
Usually made from soft materials such as soft iron, copper alloys, aluminum alloys, etc., but in some cases titanium alloys or
AISI304 etc. are also used.

The head portion of the putter has four types of mallet type (semi-circular), PIN type, T-shaped type and L-shaped type. Among them, the mallet type head has a thick bottom portion, which is stable. There is a feeling, but the feeling of hitting is not excellent. The PIN type head has a concave portion on the back surface, and the concave portion is connected to the neck portion and has a wide striking surface, so the center of the ball can be reliably caught,
The occurrence of miss shots can be reduced. Since the shaft is joined to the center of the T-shaped head, the center of the ball can be reliably captured. Like other clubs, the L-shaped head part has a shaft joined to the base of the head part, so that the swing can be performed smoothly, but there is a drawback in that the center of the ball can be easily removed when hit.

Next, a method of manufacturing the iron-based alloy golf club head will be described. As shown in FIG. 1, there are two types of current iron head manufacturing methods, a precision casting method such as the lost wax method and a forging method, and another method is surface plating (for example, nickel, cobalt, diamond). Etc.) or fitting process, etc. As a whole, the lost wax casting method is low in cost and the forging process method is excellent in various fields. FIG. 2 shows the mechanical properties of the alloy for manufacturing the iron head by the lost wax casting method and the forging processing method.

The current iron head is designed in consideration of how to hit accurately,
Some of the effects will be described below. 1. Head size of: In general, but the volume of the wood club head is between 280cm ³ ~310cm ^3, while others reach 400 cm ^3, there is also iron head oversized. Their purpose is to enlarge the face surface (sweet spot), increase the success rate of hitting, and extend the flight distance. 2. Low center of gravity: With the current state of the art, lowering the center of gravity allows the face surface to be struck accurately and increases the torsional inertia, thus enabling a longer flight distance. 3. Low air resistance and enhanced face surface: Computer-aided design (CAD) has recently changed the shape of the head to provide a stable swing, hit the face surface accurately, and prevent the loss of twisting energy By doing so, different centers of gravity and faces with reduced air resistance coefficients are formed, and iron or wood face surfaces are manufactured by the high-pressure pushing method.

Further, club heads currently mass-produced are required to meet the following requirements. 1. Corrosion resistance requirement: Normally, precipitation-hardened 17-
It is common to perform a salt spray test on 4 PH stainless steel, in which case temperature: 35 ° C, NaCl: 5%, time: 48 hours.
Done in the environment. 2. Material Performance Requirements Used for Wood Club Heads:
Generally, the tensile strength is required to be in the range of 1100 to 1500 Mpa and the elongation is basically required to be 10%, but naturally the higher the tensile strength and the numerical value of the elongation are, the better. And the space of the sweet spot is expanded. 3. Material performance requirements for iron club heads: Generally, tensile strength is required to be in the range of 700 to 1000Mpa and elongation is basically required to be 10%, but naturally tensile strength and elongation are high. The more preferable, the more they increase the volume of the head portion, and the longer the contact time between the ball and the head portion, which ultimately leads to the improvement of the controllability of the ball.

Since there are standards for golf clubs and the standards are set by the weight of the club head, it is necessary to appropriately select the material density or the material strength when manufacturing the club head. A conventional metal club head is an iron-based material, for example, a corrosion-resistant material such as stainless steel or tool steel is used, and its density is in the range of 7.8 to 8.1 (/ cm ³ and is an aluminum-based material. , For example, when an aluminum alloy subjected to a precipitation hardening treatment is used, its density is within the range of 2.7 to 2.8 (/ cm ³ , and the specific strength (strength / density) of both is 1.8 × 10 ⁴ m The smaller, specific strength and some mechanical properties of the material are shown in FIG.

In recent years, the development and mass production of titanium alloys having a density in the range of 4.5 to 4.8 (/ cm ³ ) and a specific strength of 2.3 × 10 ⁴ m or more has brought about a great change in the design of golf clubs. But this titanium alloy is very expensive,
In other words, if a new material with low density, excellent elongation and toughness, constant strength, and low price is developed, the hit ball will be stabilized with appropriate strength and the face thickness will be reduced. At the same time, the controllability of the ball can be improved with excellent elongation and toughness.

Further, Fe-Al-Mn alloys have been extensively studied by experts both in Japan and abroad, and by adjusting the alloy composition, the Fe-Al-Mn alloys have excellent strength, toughness, and cold resistance. It was found that the material has properties such as heat resistance, heat resistance, and abrasion resistance. The followings are the literatures related to these studies. 1. 1988 “Effect of Manganese” by CHKao et al.
on the Oxidationof Fe-Mn-Al-C Alloys ”(Journal of
Materials Science Vol. 23, p. 744). 2. 1990 “Effect of Potential” by JBDuh and others
on the Corrosion Fatigue Crack Growth Rate of Fe-A
l-Mn Alloy in 3.5% NaCl Solution (Corrosion No. 46
Volume 983). 3. “An Assessment of F” by JC Benz, etc. in 1985
e-Mn-Al Alloys as Substitutes for Stainless Steel
s ”(Journal of Metals 36 pages) 4. 1988“ Age Hardening o ”by Kzunori Sato et al.
f an Fe-30Mn-9Al-0.9C Alloy by Spinodal Decompositi
on ”(Scripta Metallurgica, Vol. 22, Vol. 6, page 899) 5. 1998“ A Further Contribut ”by KH Han et al.
ion to the Phase Constitution in (Fe _0.65 Mn _0.35 )
_0.83 Al _0.17 -xC Pseudo-Binary System ”(Scripta Metal
lurgica Vol. 22, page 1873). 6. 1990 “The Microstructures a” by KHHan
nd Mechanical Prorerties of an Austenitic Nb-beari
ng Fe-Mn-Al-C Alloy Processed by Controlled
Rolling ”(Pages of Materials Science and Engineering). 7. 1990 US Patent No. 4968357 by TFLiu.
“Hot-Rolled Alloy Steel Plate”. 8. 1986 “The Microstructur” by SCTjong et al.
e and Stress CorrosionCreaking Behavior of Precip
itation-Hardened Fe-8.7Al-29Mn-1.04C Alloyin 20%
NaCl Solution ”(Materials Sciene and Engineering 2
(Page 03). 9. 1996 “Experimental Study” by XJ Liu et al.
of the Phase Equilibria in the Fe-Al-Mn System ”(M
et allurgical Transactions A Vol. 27, page 2429). 10. 1960 Schmatz, DJ “Structure and P
roperties of Austentic Alloys Containing Aluminum a
nd Silicon ”(Trans.ASM Vol. 52, page 898). 11. 1975“ Phase Tras ”by Krivonogov, GS and others.
formation Kinetics inSteel 9G28Yu9MVB ”(Phys.Met.
& Metallog Vol. 4, p. 29). 12. April 1978 Ban Anji, SK “An Ansteni
tic Stainless SteelWithout Nickel or Chromium ”(M
et.Prog. page 59). 13. 1981 “Phase Decomposi” by Charles, J. et al.
tion of RapidlySolidified Fe-Mn-Al-C Austenitic Al
loys ”(Met. Prog. 71 pages). 14. 1982“ Development of Ox ”by Grcia, J. et al.
idation Resistant Fe-Mn-Al Alloys ”(Met. Prog. 47
page). 15. 1983 “New Stainless Stee” by Wang, R.
l Without Nickel or Chromium for Alloys Applicati
ons ”(Met. Prog. page 72).

Next, scholars and experts of the past Fe-Al-
The research results of Mn alloys will be explained. 1. Corrosion resistance: Fe-Al-Mn is already used by scholars and experts in Japan and abroad
Studies have been conducted on uniform corrosion, stress corrosion, bubble corrosion, high temperature corrosion, pitting corrosion and hydrogen diffusion of alloys.The results of research by Charles et al. Show that the content of aluminum element in Fe-Al-Mn alloy is 6.5 wt% or more. At that time, a single protective layer (Al ₂ O ₃ ) is formed on the surface, which is superior in corrosion resistance to ordinary carbon steel and low alloy steel at room temperature, and has properties similar to AISI 4xx stainless steel in a neutral environment. Have.
Furthermore, in 1987, SC Chang et al. Proposed austenitic, ferritic and biphasic Fe-Al-Mn alloys with pH values of 5-5.
The linear corrosion rate in the Fe-Al-Mn alloy when immersed in artificial seawater in the range of 8 was obtained. According to the research results, when elements such as aluminum (Al), chromium (Cr), silicon (Si) and molybdenum (Mo) are added, the uniform corrosion resistance of Fe-Al-Mn alloy in seawater is improved. In the case of a dual-phase Fe-Al-Mn alloy, pitting corrosion easily occurs in the ferrite phase, and when the element of molybdenum (Mo) is added, the uniform corrosion and pitting corrosion of the alloy are reduced. all right. Also, in 1988 J.
According to a study on corrosion fatigue phenomenon of Fe-Al-Mn alloy in NaCl solution by B. Duh et al., The stacking fault energy of Fe-Al-Mn alloy is AISI316.
It was confirmed to be lower than stainless steel. Thereby,
It was found that the Fe-Al-Mn alloy has excellent fatigue resistance. 2. Heat resistance: According to a study on the thermal oxidation resistance of Fe-Al-Mn alloy by SCChang et al.
It was confirmed that the addition of Si: 1% and Cr: 3% improves the thermal oxidation resistance of the alloy, while increasing the C content decreases the thermal oxidation resistance. Also, in 1989 WSYang
According to his research, it has been found that when the Fe-Al-Mn alloy is placed in a high-temperature air atmosphere or a nitrogen atmosphere, nitrogen infiltrates to easily form an AIN structure. 3. Castability and fluidity: Fe-Al-Mn alloy has face-centered cubic (FCC) structure at room temperature, and its ductility is superior to that of body-centered cubic (BCC) commercial cast steel and cast iron. Further, as can be seen from the research results by scholars and experts in the past, the Fe-Al-Mn alloy has excellent castability and fluidity, but the cast Fe-Al-Mn alloy is more mechanical. It has been found that the properties are improved. For example, the brittleness of an aluminum alloy having a high content or a normal content, the toughness of an alloy of a normal content of aluminum and a low content of manganese, and the toughness of a low content of aluminum are both excellent. Further, it was also confirmed that more excellent strength and elongation can be obtained by performing precipitation hardening by heat treatment after forming a cast member by casting.

In 1999, in a paper by Liu Xingfan, a master's student of Pingtung University of Science and Technology of the Republic of China, taught by the present inventor,
During the study of iron-based alloy sheets with l: 10% -Mn: 5-40% -C: 1.0%, the following was discovered. (1) The thin plate has a typical microstructure of α + γ dual-phase steel, and when observed with an electron microscope, the γ phase shows γ + κ +
It is a mixed section of κ ', and the α phase is a mixed section of DO ₃ + κ ¹¹ ,
Kappa phase therein Hitsuideka Ll ₂ structure (Fe, Mn) ₃ is AlC _X carbide, kappa 'is Tsuideka (Order) L'l of ₂ structures (Fe, Mn) ₃ AlC _X
It is a carbide. Furthermore, they reduce the area of the α phase in the biphasic tissues due to the increased Mn content. (2) The Mn content in the alloy is 5 to 40 w.t. When adjusted to%, the hardness value will be in the range of HR _c 31 to 44, the tensile strength value will be in the range of 65 to 91 Kg / mm ² , and the elongation will be 16%.
Within the range of ~ 30%. Further, the Mn content is 15 w.t. When adjusted to%, the hardness value of the Fe-Al-Mn alloy becomes HR _c 43.3 and the tensile strength value becomes 90.5 Kg / mm ² , and both maximum values can be obtained. 4. High strength and high toughness alloy: High strength and high toughness Fe-A
The l-Mn alloy steel has both the ductility of austenite-based stainless steel and the strength after quenching and tempering of general alloy steel, but over the years of research, the Fe-Al-Mn alloy with high strength and high toughness has been developed. It has been found that it is necessary to perform the following processing steps in order to obtain steel. (1) The composition range of Fe-Al-Mn element content is Al: 8.0-1
0.0wt. %, Mn: 25.0-30.0 wt. %, C: 1.0 wt. %. (2) By performing solution heat treatment at a temperature of 950 to 1200 ° C., a complete austenite phase having a face centered cubic (FCC) structure is obtained. (3) Next, by performing aging treatment at a temperature of 450 to 750 ° C. for a predetermined time, fine (F
e, Mn) ₃ AlC _X Phase carbide is precipitated.

In addition, “Hot-Rolled A” developed by Professor Liu Masufeng of Materials Research Institute of the University of Transport, Republic of China was developed by a new alloy design.
"Lloy Steel Plate" patent application.
-Al-Mn alloy steel does not need to be further heat treated after hot rolling, and its mechanical properties are better than those of commercial or military QT alloy steel sheets that have undergone austenitizing, quenching and tempering. It was confirmed to be excellent. Also, adjusting the content of the components of the Fe-Al-Mn-C alloy,
By carrying out solution heat treatment, quenching treatment and aging treatment, the tensile strength is within the range of 80 to 200 ksi and the yield strength is 70 to
In the range of 160 ksi, mechanical properties with elongation in the range of 50-25% were obtained. Furthermore, the content of elements such as aluminum, manganese, and carbon is appropriately adjusted, and a small amount of titanium, niobium, and vanadium elements (Ti + Nb + V ≦ 0.5 wt.)
When the alloy is added and subjected to a sophisticated alloy design and hot rolling (no further heat treatment is required after that treatment), the tensile strength is 120
Within the range of ~ 200ksi, the yield strength is within the range of 80-160ksi, while the elongation is within the range of 60-30% and the impact strength is within the range of 180-40ft-lb. The mechanical properties have been found to be superior to austenitized, quenched and tempered commercial or military QT alloy steel sheets, as described, for example, in U.S. Pat. No. 4,968,357.

FIG. 4 shows the results of a scholar's study of typical components and mechanical properties of Fe-Al-Mn alloys.

The present inventor has Al: 9.2%, Mn: 30%, C: 1.0%
As a result of conducting research and analysis on iron-base alloys containing Al and 7.8%, Mn: 30%, C: 0.8%, etc., Al: 10%, M
When heat-treated for 1 hour at 1050 ° C. on an iron-based alloy with n: 30% and C: 1.0%, its hardness value is HR _b 94.7-88.4, and tensile strength value is 922-805 Mpa. , The yield strength was 640-560Mpa, the elongation was 48-57%, and the density was 6.68-6.84g / cm ³ . Furthermore, as a result of conducting a salt spray test with 5% salt water for 48 hours, its corrosion resistance is not excellent,
Moreover, the surface roughness of the material after hot forging at 1080 ° C. was Ra = 3.2 to 6.1 μm. Also, Mn: 25-31%, Al: 6.
When an iron-based alloy containing 3 to 7.8%, C: 0.65 to 0.85%, and Cr: 5.5 to 9.0% is subjected to appropriate forging and heat treatment, good results are obtained in a salt spray test and the elongation is also increased. It was found to be retained within the range of 60-80%.

[0022]

[Problems to be Solved by the Invention] As described above, Fe-A
Since the l-Mn alloy has excellent mechanical properties and low density properties, it can be applied to any golf club head. Therefore,
For example, as shown in ROC Patent No. 58525, golf club heads using Fe-Al-Mn alloy steel have been developed one after another in Japan in recent years. However, the density of the alloy steel is about 6.65.
It is in the range of up to 6.95 g / cm ³ and is not excellent in corrosion resistance.

[0023]

Means for Solving the Problems The present invention provides Mn: 28.0 to 3
1.5wt%, Al: 7.8-10.0wt%, C: 0.90-1.10wt
%, Ti: 0.35 to 2.5 wt% and the balance of Fe.
An iron-based alloy material that is 6.1 to 6.6 g / cm ³ , by hot forging the iron-based alloy material at a temperature of 900 to 1100 ° C.,
A low-density iron-based alloy material for a golf club head, the surface roughness of which is 3 μm or less.

[0024]

The present invention is to solve the above-mentioned problems.
n: 28.0 to 31.50 wt. %, Al: 7.8 to 10.0 wt. %, C: 0.90
~ 1.10 wt. % And Ti: 0.35 to 2.5 wt. % As the main composition component, and Si: 0.8-1.50w with excellent atmospheric corrosion resistance.
t. % Or Cr: 5.0 to 7.0 wt. % May be added, and the other component is Fe. Further, by cooling the cast member or after plastic working, by heat treatment at a temperature of 950 to 1270 ° C. for 1 to 24 hours, it is possible to obtain an austenite base and a different proportional (Ti, Fe) C _X precipitation phase, Since this material density is in the range of 6.1 to 6.6 g / cm ³ , it is possible to provide a material for a golf club head which has a low density and is excellent in rust prevention.

[0025]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 5 is a comparative view showing the components of the low density iron-based alloy material for a golf club head according to the present invention.
Is a comparative table showing the mechanical properties of the low density iron-based alloy material for a golf club head according to the present invention, and FIG. 7 is the hot forging temperature and surface of the low density iron-based alloy material for a golf club head according to the present invention. It is a diagram showing the relationship with roughness,
FIG. 8 shows (a) a metallographic phase diagram and (b) a scanning electron microscope SEM diagram of a low-density iron-based alloy material for a golf club head according to the present invention after heat treatment at a temperature of 1100 ° C. for 2 hours. 9 (a), 9 (b), and 9 (c) are graphs showing the (Ti, Fe) _Cx precipitation phase content of the alloy made of the low-density iron-based alloy material for a golf club head according to the present invention. FIG. 10 is a component composition diagram by an energy dispersive X-ray spectrometer (EDS) of the (Ti, Fe) C _X precipitation phase in the alloy made of the low density iron-based alloy material for a golf club head according to the present invention. ,
11 (a), (b), and (c) show [001] and [-] in the (Ti, Fe) _Cx precipitation phase of the alloy made of the low-density iron-based alloy material for golf club heads according to the present invention, respectively. 12 (a) and 12 (b) are scanning electron microscopes (SEM) of the low-density iron-based alloy material for a golf club head according to the present invention, respectively. Microscopic photograph by [1
FIG. 13 is a photograph of a cast head for a golf club and a forged face plate manufactured from the low density iron-based alloy material for a golf club head according to the present invention.

The low-density iron-based alloy material for a golf club head according to the present invention contains Fe, Mn, Al, C and Ti elements as main composition components, and Si and Cr elements may be further added thereto. . More specifically, the Mn content is 28.0 to 31.5 wt. %, And the Al content is 7.8 to 10.0 wt. %, And the content of C is
0.90 to 1.10 wt. %, And the Ti content is 0.35 to 2.5 wt.
%, And the Cr content is 5.0 to 7.0 wt. %, And the Si content is 0.8 to 1.5 wt. %, And the other components are occupied by Fe. The ranges of these components are shown in FIG.
No. 1 to 10 of them are the component ranges of the present invention, and No. 11 to
20 is a comparative example.

As shown in FIG. 6, the No. 2 alloy is 1
It is a value when heat treatment is performed at a temperature of 100 ° C for 2 hours. According to it, the tensile strength is 986Mpa and the yield strength is
763.4Mpa, elongation 38.5%, density 6.518g
/ with cm is ^3, as a result of the 48-hour salt spray test with 5% salt water, and the results hitting test was Tsu issued 3000 was passed together. The No. 6 alloy is the value when heat-treated at a temperature of 1100 ° C for 2 hours, and the tensile strength is
The yield strength is 1247.4 Mpa, the yield strength is 895.6 Mpa, and the elongation is 10.1%, all of which meet the standard values for normal club head manufacturing. Furthermore, the density is 6.273 g / cm ³
The results of the salt spray test with 5% salt water for 48 hours and the result of the impact test 3000 issued were both acceptable. The No. 11 alloy is that shown in U.S. Pat.No. 4,968,357, its tensile strength is 1321.4 Mpa and its yield strength is 1
242.8Mpa, elongation is 36.9%, density is 6.871g
It was / cm ³ . The No. 12 alloy is also shown in U.S. Pat.No. 4,968,357, its tensile strength is 878.5 Mpa, yield strength is 635.7 Mpa, elongation is 27.8%, density is 6.695 g / It was cm ³ . 5% for materials No. 11 and 12 above
The results of both the salt spray test with salt water for 48 hours and the impact test of 3000 shots failed, did not reach the ideal standard value, and the density exceeded the preset target value.

The No. 19 alloy is the value when heat-treated at a temperature of 1100 ° C. for 2 hours, and its tensile strength is 834.5 Mpa.
The yield strength is 632.9 Mpa, the elongation is 37.5%, the density is 6.738 g / cm ^{3, and} it is 48% with 5% salt water.
Both the result of the time salt spray test and the result of the impact test 3000 issued were acceptable, but the density exceeded the preset target value. The No. 20 alloy is a value when heat-treated at a temperature of 1100 ° C. for 2 hours, its tensile strength is 821.5 Mpa, yield strength is 618.9 Mpa, and elongation is 43.5%. The density is 6.649 g / cm ³ and
The result of issuing the impact test 3000 and the result of the salt spray test with 5% salt water for 48 hours were acceptable, and the density did not exceed the preset target value.

Further, as shown in FIG. 7, the No. 2 alloy is forged into a golf club head at a temperature of 900 to 1200 ° C., and the surface roughness at that time increases as the temperature rises.
It was found to change from 2.4 μm to 5.8 μm. Therefore, it is necessary to perform hot forging at a temperature of 1100 ° C. or less in order to achieve a high surface roughness of 3 μm or less.

The reasons for limiting the components of various additive elements will be described in detail below. Mn: Usually, Mn coexists with Fe and easily bonds with S, so that the adverse effect of S on the alloy due to thermal embrittlement can be prevented and the oxide in the alloy can be removed. Furthermore, in the high carbon steel state, Mn combines with C to form Mn ₃ C, and at the same time forms a solid solution with Fe ₃ C to form (Fe, Mn) ₃ C, thus enhancing the strength and hardness of the alloy. You can Therefore, when the Mn content is less than 23.5 wt%, a ferrite phase is likely to occur after the manufacturing process or after completion, which may adversely affect the workability and elongation, and when the Mn content is 32 w.t.% or more. Is β-Mn
Since the phase precipitates at grain boundaries and becomes brittle, the Mn content in the alloy of the present invention should be 28.0 wt% to 31.5 wt%.
Need to be limited between.

Al: Al is an excellent oxygen scavenger, can suppress the growth of crystal grains, can form oxides or nitrides in a dispersed manner, and can also improve the corrosion resistance, extensibility, workability and toughness of the alloy. And so on. Therefore, the Al content is
If it is more than 7.3 wt%, excellent corrosion resistance can be obtained, and if the Al content is more than 10.5 wt%, B2 or DO ₃ will be precipitated and brittleness will increase, so the Al content range in the alloy will be limited. The limit must be between 7.8wt% and 10.0wt%.

C: The C element not only has the function of precipitating carbides, but also stabilizes the austenite phase by increasing the C content and decreasing the ferrite phase. Therefore, when the C content is more than 0.5 wt%, the material can stably form an austenite phase, but when Ti is added to the alloy,
It is necessary to adjust the C content to 0.9 wt% or more. For example, the No. 17 alloy in FIGS. 5 and 6 has a C content of 0.81.
wt%, and when it was heat-treated at a temperature of 1100 ° C. for 2 hours, its density was 6.517 g / cm ³ , which was lower than the set target, but the result of the salt spray test was unacceptable. Further, when the C content was 1.3 wt%, the amount of carbide precipitated at the grain boundaries increased and the ductility was poor. Therefore, it is necessary to limit the C content in the material of the present invention to the range of 0.90 to 1.10 wt%.

Cr: When Cr is added to the material, not only the corrosion resistance and oxidation resistance of the material can be enhanced, but also the hardness and high temperature strength of the material can be enhanced, and especially the wear resistance of high carbon steel is remarkable. Although effective, club heads made of the material cannot pass the salt spray test if the Cr content is less than 5.5 wt%. For example, as shown in FIGS. 5 and 6, the Cr content in the No. 20 alloy is 3.82 wt%
In the case of, the result of the salt spray test is unacceptable, and when the Cr content is 8.0 wt%, both phases of austenite and ferrite are formed in the alloy and the corrosion resistance of the alloy decreases, so that The club head cannot pass the salt spray test, and the alloy No. 19 also cannot pass the salt spray test because the Cr content is 8.77 wt%. Therefore, the Cr content in the material of the present invention is 5.0 to 7.0 w.
It is necessary to limit the range to t.%.

Si: Si prevents the formation of pores in the alloy, enhances the shrinkage action, and also improves the fluidity of the molten steel, but the alloy becomes brittle when the Si content is more than 1.5 wt%. It will be easier. For example, the alloy No. 15 has a Si content of 2.01 wt% and is not excellent in elongation. Therefore,
The addition of 0.8 wt% to 1.5 wt% Si to the alloy can achieve the elongation target.

Ti: Ti can reduce the density of the material and enhance the corrosion resistance of the material, but the Ti content is
When it is less than 0.35 wt%, it is difficult for those effects to appear,
When it is 2.5 wt% or more, the elongation rate of the alloy decreases,
It will be 10% or less than the required growth rate. Furthermore, the Ti content is set to 0.
The addition in the range of 35～2.5Wt%, it is possible to form the material into the austenitic base and different ratios (Ti, Fe) microstructure of C _X precipitated phase, the (Ti, Fe) C _X precipitated phase As shown in FIGS. 8 (a), (b) and 9 (a), (b), (c), crystallization of the material was confirmed, and analysis by an energy dispersive X-ray spectrometer (EDS) was performed. It was also confirmed from Fig. 10 that it was a carbide composed of elements of Ti, Fe, and C. Furthermore, as shown in Fig. 11, a transmission electron microscope (TE
It was also confirmed by (M) that the (Ti, Fe) C _X precipitate phase had a face-centered cubic structure (FCC). Therefore, the density of the material can be maintained within the range of 6.6 to 6.1 g / cm ³ by solid-dissolving a low-density Ti element in the base or by precipitating (Ti, Fe) C _X. Therefore, it is possible to manufacture a golf club head having a larger volume with the weight satisfying the specification limit by the material. Therefore, in the material of the present invention
It is necessary to limit the content of Ti element within the range of 0.35 to 2.5 wt%. As described above, the iron-based alloy of the present invention is not
Ra = 3 μm if hot forging is performed at a temperature of 0 ℃ to 1100 ℃
It is possible to obtain the following excellent surface roughness, 1100 ℃
When thermal processing is performed at a temperature of 1200 ° C., not only the oxide layer increases but also the surface roughness Ra of the member becomes larger than 3 μm, which adversely affects the quality of the iron club.

[0037]

Since the present invention has the above constitution, the following
There is such an effect. 1. Mechanical strength: While controlling the content of Cr, Mn, C,
By adding Ti to the material and crystallizing the material
As shown in FIG. 8, its tensile strength is 921.5-1247.4M.
Within the range of pa, the yield strength is within the range of 756 ~ 895.6Mpa
Therefore, if a club head is made of this material,
It is possible to fully utilize the characteristics of Ruff Club, and it is more suitable.
Material strength can be further improved by applying appropriate aging treatment.
it can. For example, in case of No. 3 and No. 4 shown in FIG.
Gold is in its base (Fe, Mn)₃AlC _XCarbide precipitated
It is a thing. 2. Low density: Controls the content of Cr, Mn, C, and
Ti element within the range of 0.35 to 2.5 w.t.% may be added to the material.
Causes the material to form an austenite phase base
In addition, some low density Ti elements and different ratios are added to the base.
Low density (Ti, Fe) C_XSolid solution of the precipitation phase. Therefore, the material
The density of the material is 6.6 to 6.1 g / cm³Can be kept within the range of
A go that has a larger volume with a weight that meets the specification limits.
Ruff club heads can be manufactured. 3. Corrosion resistance: Excellent corrosion resistance both in the material and in the atmosphere
Cr in the range of 5-7 w.t.% and 0.35-2.5 w.t.
By adding Ti within the range of%,
The corrosion resistance can be improved and the manufacturing cost can be reduced.
it can.

As described above, the low density, high strength, corrosion resistance, and forged surface quality are improved by using the low density iron-based alloy material for golf club head of the present invention at the proper composition adjustment and forging temperature. Can be made.

[Brief description of drawings]

FIG. 1 is a characteristic comparison table of golf club heads manufactured by a lost wax casting method and a forging method.

FIG. 2 is a comparative diagram of mechanical properties of conventional golf club head materials.

FIG. 3 is a comparison diagram of mechanical properties and specific strengths of conventional golf club head materials.

FIG. 4 is a comparison table of typical composition components and mechanical properties of a conventional Fe-Al-Mn alloy.

FIG. 5 is a comparative diagram showing components of a low density iron-based alloy material for a golf club head according to the present invention.

FIG. 6 is a comparative table showing the mechanical properties of the low density iron-based alloy material for a golf club head according to the present invention.

FIG. 7 is a diagram showing a relationship between hot forging temperature and surface roughness in the low density iron-based alloy material for a golf club head according to the present invention.

FIG. 8 shows (a) a metallographic diagram and (b) a scanning electron microscope SEM of a low-density iron-based alloy material for a golf club head according to the present invention after heat treatment at a temperature of 1100 ° C. for 2 hours. It is a figure.

9 (a)-(c) are (Ti, Fe) C _X alloys made of a low-density iron-based alloy material for a golf club head according to the present invention.
It is a figure which shows precipitation phase content.

FIG. 10 is a component composition diagram by an energy dispersive X-ray spectrometer (EDS) of a (Ti, Fe) C _X precipitation phase in an alloy made of a low-density iron-based alloy material for a golf club head according to the present invention.

11 (a)-(c) are (Ti, Fe) C alloys made of a low-density iron-based alloy material for a golf club head according to the present invention.
FIG. 3 is a diffraction diagram in the [001], [-1,1,2] and [001] directions in the _X precipitation phase.

12 (a) and 12 (b) are respectively a micrograph by a scanning electron microscope (SEM) and a [100] direction diffraction diagram of a low density iron-based alloy material for a golf club head according to the present invention.

FIG. 13 is a photograph of a golf club casting head and a forged face plate manufactured from the low density iron-based alloy material for a golf club head according to the present invention.

Claims (3)

[Claims] 1. Mn: 28.0 to 31.5 wt%, Al: 7.8 to 10.0
wt%, C: 0.90~1.10wt%, Ti: it consists 0.35～2.5Wt% and Fe balance, density a ferrous alloy material is 6.1~6.6g / cm ^3, 900~ a ferrous alloy material A low-density iron-based alloy material for a golf club head, which has a surface roughness of 3 μm or less by hot forging at a temperature of 1100 ° C. 2. The iron-based alloy material contains Cr: 5.0 to 7.0 wt%
The low-density iron-based alloy material for a golf club head according to claim 1, characterized in that the corrosion resistance to a salt spray test for 48 hours is improved by adding a. 3. The iron-based alloy material contains Si: 0.8-1.5 wt%
The low-density iron-based alloy material for a golf club head according to claim 1, wherein the fluidity at the time of casting is increased by adding a.