Case-hardened stainless steel foundry alloy and methods of making the same

Abstract

A case-hardened stainless steel part and method of making the same are disclosed. The part comprises a case defining a first layer proximate the outer surface of the part and a core defining a second layer adjacent the case and distal from the outer surface. The core has a hardness of from about 80 on the Rockwell Hardness B Scale to about 50 on the Rockwell Hardness C Scale. The case has a hardness of not less than about 30 equivalence on the Rockwell Hardness C Scale.

Description

FIELD OF THE INVENTION [0001] The present application relates to hardenable stainless steels and, more particularly, to case hardened stainless steels suitable for the manufacture of golf club heads. BACKGROUND OF THE INVENTION [0002] Many steels suffer from a number of drawbacks when used to manufacture irons and wedges for golf club heads. For example, golf professionals generally like clubs with a balance of corrosion resistance and “feel,” which relates to the balance of surface hardness and core hardness, as well as a high degree of polish. The core hardness is generally responsible for the feel of the club, while the surface hardness is generally responsible for the aesthetic appearance of the club, as well as its corrosion resistance and scratch resistance. The lack of stainless casting alloys with the desired properties has forced golf club designers to use chrome plated alloys for such applications. However, chrome plating is expensive and environmentally undesirable. Thus,...

AI Technical Summary

Benefits of technology

[0004] The cast part preferably has an outer surface and a case that defines a first layer proximate the outer surface. The cast part further comprises a core that defines a second layer distal from the outer surface. The core preferably has a hardness from about HRB 80 (Rockwell Hardness B Scale) to about HRC 50 (Rockwell Hardness C Scale) and more preferably has a hardness from about HRC 20 to about HRC 34. The case preferably has a hardness of not less than about HRC 30 equivalence, and more preferably has a hardness of not less than about HRC 50 equivalence. It is also preferred that the case and core each have a carbon concentration, with the carbon concentration in the case being higher than that in the core.

[0005] In another aspect of the present invention, a method of making a case-hardened stainless steel part is provided. The method comprises providing a cast part formed from a stainless steel alloy, wherein the alloy comprises chromium, generally in an amount of from about 15.5 to about 18.5 percent by weight of the alloy,

Problems solved by technology

Many steels suffer from a number of drawbacks when used to manufacture irons and wedges for golf club heads.

The lack of stainless casting alloys with the desired

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