| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface treating method for a ferrous material capable of the stabilization of the quality, the prolongation of a salt bath life and the remarkable reduction of the treating time and capable of industrial mass production and a salt bath furnace used therefor. SOLUTION: A ferrous material is subjected to nitriding treatment to form a nitriding layer composed of at least either iron nitride or iron carbonitride on the surface, and the ferrous material is held under heating at 500 to 700 deg.C in the following treating agent (A), by which chromium is diffused into the nitriding layer to form at least either compd. layer of chromium nitride or chromium carbonitride: (A) a treating agent consisting essentially of the following component (a) and contg. the components (b) and (c); (a) at least either the chloride of alkali metal or the chloride of alkaline-earth metal, (b) glass consisting essentially of silicon oxide, and (c) chromium.
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