JP2012507632A - Ultra-high strength stainless steel alloy strip, method of manufacturing the same, and method of using the strip to manufacture a golf club head - Google Patents

Abstract

  Stainless steel elongated and thin strip products are disclosed. This product is in weight percent up to 0.03 C, up to 1.0 Mn, up to 0.75 Si, up to 0.040 P, up to 0.020 S, 10. 9 to 11.1 Cr, 10.9 to 11.1 Ni, 0.9 to 1.1 Mo, 1.5 to 1.6 Ti, and up to 0.25 Al, It is made from a corrosion resistant alloy containing 0.7 to 0.8 Nb, a maximum of 1 Cu, a maximum of 0.010 B, and a maximum of 0.030 N. The balance of this alloy is iron and normal impurities. This elongated and thin strip product exhibits a room temperature tensile strength of at least 280 ksi (1930.5 MPa) in the solution heat treatment and age hardening conditions. A method of manufacturing the strip material and a method of manufacturing a golf club head using the strip material are also disclosed.

Description

  The present invention relates to a stainless steel strip material, and more particularly to a stainless steel strip product having a very high tensile strength, a method of manufacturing the product, and a method of using the strip product to manufacture a golf club head. is there.

  Golf club manufacturers are constantly seeking high-strength faceplate materials. The very high strength allows the faceplate portion to be thinner and thus lighter, which gives designers more room in golf club head design. ing. In addition, corrosion resistant materials are preferred over non-stainless materials because they do not require surface coating or plating that would be removed during use.

  The current solution to this problem is to use standard PH stainless steel alloys such as CUSTOM 455 alloy and newly designed stainless alloys such as CUSTOM 465 alloy and CUSTOM 475 alloy. However, CUSTOM 455 alloy and CUSTOM 465 alloy do not exhibit the strength levels as desired in new golf club designs. CUSTOM 475 alloy provides very high strength, but in addition to being highly alloyed and acceptable in the golf club manufacturing process, it is expensive for golf club manufacturers.

  In addition, many golf club heads are generally manufactured using a cast body with a face plate. Cast body materials are typically made from precipitation hardening stainless steels such as 17-4 PH stainless steel or 15-5 PH stainless steel. Golf club heads are generally made by welding the face plate to the cast body and then heat treating the entire face plate and cast body assembly to achieve the final properties. Alloys commonly used for golf club head cast bodies have a melting temperature of about 1900 ° F. (1038 ° C.), whereas known faceplate materials range from 1550 ° F. to 1800 ° F. (843). A melting temperature in the range of from 0 ° C to 982 ° C. This mismatch in heat treatment temperature results in the club body and / or face plate never exhibiting optimum properties in the heat treated state after assembly of the golf club head. In addition, since CUSTOM 475 alloy cannot be remelted after assembly of the golf club head, the alloy often requires a totally different manufacturing process.

  The aforementioned disadvantages of the known materials are overcome to a great extent by the stainless steel strip product according to the invention.

According to one aspect of the invention, in weight percent,
C 0.03 max
Mn up to 1.0
Si maximum 0.75
P 0.040 max
S 0.020 max
Cr 10.9 to 11.1
Ni 10.9 to 11.1
Mo 0.9-1.1
Ti 1.5-1.6
Al maximum 0.25
Nb 0.7-0.8
Cu maximum 1
B Max 0.010
N 0.030 max
A stainless steel strip product is obtained which is made of a corrosion-resistant alloy which contains iron and the balance is iron and normal impurities. This elongated and thin strip product exhibits a room temperature tensile strength of at least about 280 ksi (1930.5 MPa) in a solution heat treatment and age hardened state.

  According to another aspect of the invention, a method for producing a thin strip product is obtained. The method includes the step of casting an corrosion resistant alloy having the weight percent composition described above to make an ingot. The ingot is hot processed to form an elongated strip material. The strip material is then heat treated under conditions of time and temperature to exert an ultimate tensile strength of at least about 280 ksi (1930.5 MPa) at room temperature.

  According to yet another aspect of the invention, a method for manufacturing a golf club head is obtained. The method includes the step of casting an corrosion resistant alloy having the weight percent composition described above to make an ingot. The ingot is hot worked to form an elongated strip, which is then heat treated under conditions of time and temperature that benefit from the machinability and processability of the strip. Next, the strip material is machined to form a face plate for a golf club head. The method further includes forming a golf club head body from a corrosion resistant, precipitation hardened steel alloy. The face plate is joined to the golf club body. Next, the face plate and golf club body assembly provides the desired level of hardness and strength in the golf club head body and an ultimate tensile strength of at least about 280 ksi (1930.5 MPa) at room temperature at the face plate. Heat treatment is performed under conditions of sufficient time and temperature to exhibit the thickness.

FIG. 1 is a graph showing a tensile strength as a function of aging temperature.

Preferred embodiments of the present invention can include elongated strip products having the following composition in weight percent:
C 0.03 max
Mn up to 1.0
Si maximum 0.75
P 0.040 max
S 0.020 max
Cr 10.9 to 11.1
Ni 10.9 to 11.1
Mo 0.9-1.1
Ti 1.5-1.6
Al maximum 0.25
Nb 0.7-0.8
Cu maximum 1
B Max 0.010
N 0.030 max
The balance is iron and normal impurities.

  The alloy composition is preferably melted using vacuum induction melting (VIM). The steel is cast into one or more ingot molds. The alloy is vacuum arc remelted (VAR) after the VIM process for additional cleaning. After solidification, the alloy is formed into a strip by intermediate pressing the ingot to form a billet and then hot rolling the billet to form an elongated strip. Alternatively, the strip material can be formed by hot rolling the ingot from a starting temperature of about 1900 ° F to 2250 ° F (1038 ° C to 1232 ° C). The strip can be provided in an overaged state by heating at about 1100 ° F. to 1350 ° F. (593 ° C. to 732 ° C.) for about 2 to 8 hours and then air cooling. Alternatively, in order to ensure better machinability and processability, the strip material is heated at about 1900 ° F. to 1950 ° F. (1038 ° C. to 1065 ° C.) for about 1 hour, air cooled, and about Cool at −100 ° F. (−73.3 ° C.) for about 8 hours to transform any austenite in the alloy to martensite almost completely and then warm to room temperature in air. Preferably, the strip material is cold-rolled before the heat treatment to have a final thickness or a thickness close to the final thickness. The strip material according to the present invention can be subjected to solution heat treatment in a continuous furnace at a frequency and temperature adjusted according to the situation. When applied to a golf club, the strip material is about 0.02-0.16 inch (0.5-4 mm), preferably about 0.10-0.12 inch (2.5-3. 0 mm).

  Unlike known high-strength stainless steel alloys such as CUSTOM 475 stainless alloy, the alloy strip according to the invention can be subjected to a double solution heat treatment without significant loss of properties, in particular no loss of strength. . In other words, the stainless steel strip material of the present invention can be provided in a solution heat treatment + cooled state, processed into parts, then remelted, recooled and assembled into a golf club head. After being cured, it is age hardened to exhibit the desired high strength and hardness.

As an example of an elongated strip product according to the present invention, a small heat was melted and processed. A 400 lb (181.4 kg) heat was melted by VIM + VAR and cast as an 8 inch (20.3 cm) diameter ingot. The weight percent composition of the VAR ingot is shown in Table 1 below. The balance of this alloy was iron and normal impurities.

  The ingot is homogenized at about 2300 ° F. (1260 ° C.) for 16 hours and then pressed from a starting temperature of about 2000 ° F. (1093 ° C.) to produce a 4 inch × 8 inch (10 cm × 20.3 cm) billet. I made it. The billet was hot rolled from a starting temperature of about 2250 ° F. (1232 ° C.) into a strip of 7.5 inches wide × 0.15 inches thick (19 cm wide × 3.8 mm thick). The strip was then polished to a thickness of 0.135 inches (3.4 mm) and then cold rolled to a thickness of 0.1103 inches (2.8 mm). The strip was overaged by heating at about 1146 ° F. (619 ° C.) for 5.5 hours. After cooling to room temperature, the strip material was polished to a final thickness of 0.1083 inches (2.75 mm).

  A plurality of standard strip tensile blanks were roughly cut from the overaged strip in longitudinal and transverse orientation. These blank groups were air cooled by solution heat treatment at 1850 ° F. (1010 ° C.), 1900 ° F. (1038 ° C.), 1950 ° F. (1065 ° C.) and 2000 ° F. (1093 ° C.) for 1 hour, respectively. . These solution heat-treated blanks were deep-cooled at −100 ° F. (−73.3 ° C.) for 8 hours and then warmed to room temperature in air. The blanks were then rough machined to provide a gage section of about 1/2 inch wide by about 2 inches long (width 1.27 cm x length 5.08 cm). Groups of these rough machined blanks from each solution heat treatment were aged at a temperature range of about 900 ° F. (482 ° C.) to about 975 ° F. (524 ° C.) for 4 hours and then air cooled. The test sample was finish machined after aging and tested at room temperature.

The results of tensile tests and hardness tests at room temperature are shown in Tables 2 to 4 below. In these tables, the solution heat treatment temperature (Solution Temp.) And the aging temperature (Age Temp.) Expressed in ° F (° C), and the 0.2% offset yield strength (Y. S.), ultimate tensile strength (U.S.S.) and Rockwell C-scale hardness (Hardness) as HRC.
* Strength data on these samples has been lost. However, the tester does not know the U.S. T.A. S. Is greater than 280 ksi (1930.5 MPa) and the U.S. T.A. S. Is slightly lower than 280 ksi (1930.5 MPa).

  The metallographic analysis of the test samples showed that the material heat treated at 1850 ° F. (1010 ° C.) and 1900 ° F. (1038 ° C.) had a grain size of about ASTM 8. The material heat treated at 1950 ° F. (1065 ° C.) had a grain size of about ASTM 7-8. The material heat treated at 2000 ° F. (1093 ° C.) had a crystal grain size of about ASTM 2-3. Throughout this specification, ASTM grain size means the average grain size determined according to ASTM Standard Test Procedure E-112.

  The results shown in Tables 2-4 indicate that the preferred dissolution temperature is from about 1900 ° F. (1038 ° C.) to about 1950 ° F. (1065 ° C.). Similarly, the preferred aging temperature is that of the desired 280 ksi (1930.5 MPa) U.S. T.A. S. Is about 900 ° F. to 925 ° F. (482 ° C. to 496 ° C.). U. T.A. S. A graph of the combination of melting temperature and aging temperature is shown in FIG.

  The data shown in the tables show that strip products made from the alloy compositions described in this specification have a U.S. of 280 ksi (1930.5 MPa) or higher. T.A. S. It is shown that can be demonstrated. The strip material is less polymerized than other stainless steel compositions that can exhibit the above levels of strength, and as a result, low alloy costs can be achieved. In addition, the strip material according to the present invention can be subjected to a solution heat treatment one or more times without sacrificing strength properties or toughness properties. The strip material according to the present invention allows a golf club faceplate comprising this composition to be fully compatible with the solution heat treatment temperature for precipitation hardened stainless casting alloys frequently used for golf club head bodies. The solution heat treatment is preferably performed at a temperature in the range of about 1900 ° F. to 1950 ° F. (1038 ° C. to 1065 ° C.). Therefore, the face plate and the club head body are not only the body of the club head but also the face plate that contacts the golf ball. Can be made.

  It will be recognized by those skilled in the art that changes or modifications can be made to the above-described embodiments without departing from the scope of the present invention. Therefore, it is understood that the present invention is not limited to the specific embodiments described above, but includes all modifications and changes made within the spirit of the present invention.

Claims (20)

In weight percent
C 0.03 max
Mn up to 1.0
Si maximum 0.75
P 0.040 max
S 0.020 max
Cr 10.9 to 11.1
Ni 10.9 to 11.1
Mo 0.9-1.1
Ti 1.5-1.6
Al maximum 0.25
Nb 0.7-0.8
Cu maximum 1
B Max 0.010
N 0.030 max
A thin and thin strip product made of a corrosion-resistant alloy with a balance of iron and normal impurities, and having a room temperature tensile strength of at least about 1930.5 MPa in solution heat treatment and age hardening conditions Strip products.   The elongated thin strip product of claim 1, wherein the strip product has a thickness of about 0.5-4 mm.   3. The elongated thin strip product of claim 1 or 2, wherein the alloy has an average grain size that is about ASTM 7-8 or less.   4. An elongated thin strip product according to any of claims 1 to 3, having a hardness of about 53 to 54 HRC. A method for producing an elongated thin strip product according to claim 1, comprising:
Casting the corrosion resistant alloy to make an ingot;
Mechanically processing the ingot to form an elongated strip material;
A method for producing an elongated thin strip product comprising subsequently heat treating said elongated strip material under conditions of time and temperature to exert an ultimate tensile strength of at least about 1930.5 MPa at room temperature.   The step of heat treating the elongated thin strip product comprises heating the strip material at a temperature of about 1038-1093 ° C and then heating the strip material at a temperature of about 482 ° C to about 510 ° C. The method according to claim 5.   An initial heating step includes heating the strip product at a temperature of about 1038 ° C. to about 1065 ° C., and the method removes the strip product between about the first heating step and the next heating step to about −73. Rapidly cooling to 3 ° C and then maintaining the strip product at about -73.3 ° C for a time effective to substantially completely transform any austenite in the alloy to martensite. The method according to claim 6.   8. The step of mechanically processing an ingot includes pressing the ingot to form a billet and then hot rolling the billet to form the elongated strip material. The method in any one of.   The method according to any of claims 5 to 7, wherein the step of mechanically processing the ingot comprises hot rolling the ingot to form the elongated strip material.   The method of claim 8 or 9, wherein the hot rolling step comprises heating the billet or ingot to about 1038-1232C. A method for making a golf club head from the elongated strip material of claim 1 comprising:
Casting the corrosion resistant alloy to form an ingot;
Mechanically processing the ingot to form the elongated strip material;
Heat treating the strip material under conditions of time and temperature to improve the machinability and processability of the strip material;
Cutting the elongated strip material to form a face plate for a golf club head;
Making a golf club head body from a corrosion resistant precipitation hardened steel alloy;
Bonding the face plate to the golf club head body to form a golf club head assembly;
Heat treating the golf club head assembly under conditions of time and temperature for exerting hardness and strength in the golf club head assembly and an ultimate tensile strength of at least about 1930.5 MPa at room temperature on the face plate. A method for making a golf club head, including a process.   The step of heat treating the golf club head assembly includes heating the strip material at a temperature of about 1038 ° C. to 1093 ° C. and then heating the strip material at a temperature of about 482 ° C. to about 510 ° C. 12. A method according to claim 11 comprising.   An initial heating step includes heating the golf club head assembly at a temperature of about 1038 ° C. to about 1065 ° C., the method between the first heating step and the next heating step; After the assembly is rapidly cooled to about −73.3 ° C., the time for the golf club head assembly to substantially completely transform any austenite in the alloy to martensite, about −73.3 ° C. 13. The method of claim 12, comprising maintaining   14. The step of mechanically processing an ingot includes pressing the ingot to form a billet, and then hot rolling the billet to form the elongated strip material. The method in any one of.   The method according to claim 11, wherein the step of mechanically processing the ingot includes hot rolling the ingot to form the elongated strip material.   The method according to claim 14 or 15, wherein the hot rolling step comprises heating the ingot or billet to about 1038 ° C to 1232 ° C.   The method of claim 11, wherein the step of heat treating the strip material includes overaging the strip material at about 593 ° C. to about 732 ° C. 12.   The step of mechanically processing the ingot comprises pressing the ingot to form a billet, hot rolling the billet to form the elongated strip material, and then cold rolling the elongated strip material. 14. A method according to any of claims 11 to 13, comprising reducing the thickness of the elongated strip material to a final dimension or a dimension close to the final dimension.   The step of mechanically processing the ingot includes hot rolling the ingot to form an elongated strip material, and then cold rolling the elongated strip material to reduce the thickness of the elongated strip material. 14. A method according to any one of claims 11 to 13, comprising making the dimensions close to the final dimensions or the final dimensions.   20. The method of claim 18 or 19, wherein the hot rolling step comprises heating the ingot or billet to about 1038 ° C to about 1232 ° C.