Process for case hardening steel
AssigneeKolene Corporation
InventorsThomas M. Jakubowski, William G. Wood
Life of this patent
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Abstract
A process for case hardening steel is described. A fused bath of inert salt is maintained which bath is comprised of alkali or alkali earth halides, and alkali, or alkaline earth oxides or carbonates. To this fused bath is added urea, dicyanodiamide or pyrolysis/condensation products of urea or dicyanodiamide. This will form active ions containing carbon and/or nitrogen, and either the nitrogen and/or carbon will diffuse into the surface of a steel piece suspended in the bath to form either a nitride, carbonitride or carburized case depending upon the temperature of the bath, which is maintained between above 540.degree. C. and about 950.degree. C.
Claims11
A process for forming a hardened case on a ferrous metal comprising the steps of maintaining, at a temperature from about 540.degree. C. (1000.degree. F.) to about 950.degree. C. (1750.degree. ), a fused chemical salt bath consisting essentially of a first material selected from the group consisting of alkali halides, or alkaline earth halides, or mixtures thereof;
- and a second material selected from the group consisting of alkali oxides, alkaline earth oxides, alkali carbonates, alkaline earth carbonates, or mixtures thereof;
- said bath being maintained free of cyanide and cyanate salts, suspending the metal workpiece to be case hardened in said bath;
- thereafter adding to said bath a third material or combination of materials selected from the group consisting of urea, dicyanodiamide, and any of the pyrolysis/condensation products of urea or dicyanodiamide;
- or combinations thereof at a rate which will not produce cyanide or cyanate salts whereby to form in situ active case producing ingredients to thereby produce a case on said workpiece, removing said workpiece, and thereafter maintaining said bath free of cyanide and cyanate salts, with the original first and second material.
Dependencies are inferred from the claim text.