| 摘要 |
<p>A process for the production on ferrous metal parts of a sulphurized nitrided surface layer comprising heating the parts to above 500 DEG C., preferably 560-580 DEG C. in a fused salt bath containing an alkali metal cyanide, cyanate, chloride and carbonate and active sulphur (i.e. sulphur which shows up in analysis for sulphide) which may be added in the form of a sulphite, sulphide, thiosulphate or thiocyanate of an alkali metal. The proportion by weight of cyanide is 0.5-30% (calculated as NaCN), of cyanate 10-25% (calculated as NaCNO), of chloride 20-50% (calculated as KCl) and of sulphur 0.05-0.4% (calculated as S). Case hardened steel is treated for 5-180 minutes and the bath covered with a floating layer of graphite and is then quenched or cooled in air or town gas.</p> |
