Field of The Invention The field of the invention is metal alloys.

Background of The Invention Golfers often have significant preferences with respect to characteristics of their golf clubs, including overall dimensions, color, durability, price, hardness (feel), tensile strength (toughness), etc. Over the years, some of these preferences have become quite specific in the industry, thereby limiting the range of materials that can realistically be used in fabricating golf clubs.

For example, golf club heads have been fabricated from various iron and titanium- based alloys, but each of the materials previously used in golf club heads suffers from actual or perceived drawbacks. Stainless steel heads, for example, may have a hardness (feel) and/or tensile strength (toughness) which make them undesirable for certain club head applications. Titanium club heads are expensive and difficult to fabricate.

Thus there is a need to provide novel compositions for use in fabricating stainless steel golf club heads.

Summarv of the Invention The present inventors contemplate the manufacture of golf club heads using special metal alloys that are previously unknown for such purposes. The alloys contemplated are: (1) iron based alloys that include molybdenum and/or aluminum; (2) and nickel based alloys that include boron; (3) stainless steel alloys that include manganese; and (4) and stainless steel alloys that include nitrogen.

In one class of preferred alloys, the weight percentage of molybdenum in the alloy is at least 0.5%, and more preferably 1.5-3. 5%, and still more preferably 1.8-3.0%. In another class of preferred alloys, the weight percentage of aluminum in the alloy is preferably at least 0.25%, and more preferably 0.5-2. 0%, and still more preferably 0.6- 1.75%.

In another class of preferred alloys, the weight percentage of boron is between about 0.5% to about 0.9%, the weight percentage of nickel is at least 50% In especially preferred embodiments the balance is entirely or substantially silicon and/or copper.

In another class of preferred alloys, stainless steel alloys preferably contain at least 1.0 wt% manganese, more preferably at least 1.25 wt% manganese, and still more preferably 1.5 wt% to 15wt% manganese.

In another class of preferred alloys, stainless steel alloys preferably contain at least 0.05 wt% nitrogen, more preferably at least wt% nitrogen, and still more preferably % nitrogen.

The contemplated golf club heads can be manufactured in any suitable manner, including using casting, forging or stamping, in which the special metal alloys are employed in one or more structural components of the golf club heads, including the face, sole plate, crown, insert, hosel, or even screws.

Various objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention.

Brief Description of The Drawings Figure. 1 is a table characterizing aspects of the non-ferrous elemental content of exemplary contemplated alloys using aluminum and/or molybdenum.

Figure 2 lists a preferred composition of a manganese and nitrogen containing alloy.

Detailed Description The present inventors contemplate golf club heads having at least some component containing either (1) molybdenum and/or aluminum in an iron based alloy, or (2) boron in a nickel based alloy. The term"alloy"is used herein in the broadest possible sense, and specifically includes metal alloys and ceramic alloys.

Figure 1 summarizes the composition of six exemplary classes of iron based alloys for use in manufacture of golf club heads. In all cases the listed components total less than 30% of the total weight-percent, and while not expressly stated in the table, substantially all of the remaining composition is preferably iron (Fe). It is contemplated, however, that the listed alloys may contain substantial quantities (at least 5%, 15%, 30%, or 40%) of iron which are less than 50%, and may additionally contain substantial quantities of ceramics or other materials. All percentages given herein are weight-percent, and all ranges are inclusive. The term"trace"is defined herein to mean a detectable, but non-significant amount.

Turning away from Figure 1, it is generally contemplated that alloys used in the manufacture of golf club heads, contain at least 51% iron, and at least 0.5% molybdenum, such as molybdenum. More preferred embodiments include approximately molybdenum, still more preferred embodiments include approximately 1.8%- 3.0% molybdenum. Another class of preferred embodiments include at least 51 % iron, and at least 0.25% aluminum. More preferred embodiments include approximately 0.50-2. 0% aluminum, and still more preferred embodiments include approximately 0.6-1.75% aluminum. Still another class of preferred embodiments include at least 51% iron, at least 0.5% molybdenum, and at least 0.25% aluminum. More preferred embodiments in this class include molybdenum and 0.50-2. 0% aluminum, and still more preferred embodiments in this class include 1.8%-3. 0% molybdenum and aluminum.

All of these classes may also contain substantial quantities of ceramics or other materials.

The nickel based alloys of the present invention contain boron at between about 0.5 wt% and about 0.9 wt%, with silicon comprising at least a portion of the balance.

In another class of preferred alloys, the weight percentage of boron is between about 0.5% to about 0.9%, the weight percentage of nickel is at least about 50% In especially preferred embodiments the balance is entirely or substantially silicon and/or copper.

In another class of preferred alloys, stainless steel alloys preferably contain at least 1.0 wt% manganese, more preferably at least 1.25 wt% manganese, and still more preferably 1.5 wt% to 15wt% manganese.

In another class of preferred alloys, stainless steel alloys preferably contain at least 0.05 wt% nitrogen, more preferably at least wt% nitrogen, and still more preferably % nitrogen.

Basic processes used to manufacture the alloys contemplated herein are within the knowledge of those of ordinary skill in the art. Thus, alloying can be accomplished in many different ways, including casting, such as by air melting, vacuum melting, forging, stamping, and so forth. The terms"casting","forging", and"stamping"are used herein in their commonly accepted meanings and refer to processes which form structural aspects of golf heads and face inserts.

Alloys contemplated herein may be used in the fabrication of structural elements of irons, metal woods, wedges, putters, and any other club having a club head containing a substantial portion of metal. In the case of metal woods, for example, one or more of the special metal alloys can be included in the form of a face insert, sole plate, crown plate, hosel, or weight insert. Such face inserts may advantageously measure about 2-4 mm in thickness, although greater, lesser and varying thicknesses are contemplated as well. In the case of irons, wedge, or putters, one or more of the special metal alloys can be include in the form of a face insert, weight insert, or hosel. Regardless of the type of club or club head. the special metal alloy can be pressed, brazed, screwed, welded or otherwise attached

to a mating structural aspect of the club head, or the entire club head can be fabricated from said alloy.

Examples The various claimed compositions are contemplated to produce desirable results when incorporated in one manner or another in golf club heads. Some of the improvement has to do with hardness and weighting, which affect the"feel"of the clubs during use.

Depending on the particular alloy (s) being considered, other desirable aspects may relate to other metallurgic qualities such as color or rust resistance.

Several test runs of molybdenum and/or aluminum containing alloys described herein have been produced, and standard tests have been performed. According to such tests, alloys having molybdenum have an HRC hardness of 35-50 and tensile strength of 130,000-260, 000 ksi. This is typically more than 15% harder than clubs made of non-molybdenum containing stainless steel. Golf club heads manufactured in this manner typically have 15% higher tensile strength than clubs made of non-molybdenum containing stainless steel. Among other things, the hardness is greater than HRC 40 and tensile strength greater than 200,000 ksi.

Alloys having aluminum have also been made, and have a hardness of HRB 85-HRC50 and tensile strength of ksi, depending upon heat treatment applied. These parameters can be varied using specific heat treatment techniques in accordance with the ordinary skill in the art, as exemplified by the attached data sheet.

One contemplated use of alloys having different hardness characteristics is to fabricate some clubs in a set of irons or metal woods with one hardness (soft for short irons for example) and other clubs in the same set with another hardness (harder for middle irons and harder still for long irons).

Figure 2 lists a preferred composition of a manganese and nitrogen containing alloy.

Thus, specific embodiments and applications for iron based metal alloys comprising molybdenum, aluminum, nitrogen, and/or manganese have been disclosed, as well as nickel based alloys including boron. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except as set forth in the appended claims. Moreover, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms"comprises"and"comprising"should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.