Alloy steels flame hardening

The dies themselves are generally constructed of medium carbon alloy steels, with flame-hardened lips and chrome or nickel plating on the flow surfaces. Insulation of the die body Is common to prevent temperature variations that could result from air drafts. Dies can be electrically heated, or steam or oil heat can be used. Cooling is usually provided by natural convection, though forced air can also be used. 

The flame-hardening process is used for a wide variety of applications. These include (1) parts that are so large that conventional furnace treatments are impractical or uneconomical, (2) prevention of detrimental treatment of the entire component when only small segments of die part require heat treatment, and (3) use of less costly material to obtain the desired surface properties where alloyed steels would be normally applied. Flame hardening is limited to hardenable steels (wrought or cast) and cast iron. Typical hardnesses obtained for the flame-hardened grades depend on the quench media (Table 1). The practical level of minimum surface hardness attainable with water quenching for various carbon contents is shown in Fig. 1. 

Flame or induction hardened. (2) Trademark of La Salle Co. (3) Trademark of Joseph T. Ryerson Son Inc. (4) Nitrided. (5) Usually improved by hardsurfacing. (6) Trademark of Armco Steel Corp. (7) Trademark of Crucible Specialty Metals. (8) Trademark of Huntington Alloys Inc. (9) Trademark of Cabot Corp. 

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