| 摘要 |
PROBLEM TO BE SOLVED: To activate the surface of steel by breaking a passive film on the surface of the steel, to maintain the activated state, to form a nitride layer free from unevenness and simultaneously to eliminate the complication of the equipment and the increase of the cost caused by the toxicity and corrosivity of atmospheric gas. SOLUTION: In a temp. rising stage to a nitriding treating temp. and also in a gaseous nitrogen atmosphere contg. hydrogen sulfide, steel having a passive film is heated, is subjected to sulfurizing treatment, is thereafter held under heating for a prescribed time in a nitriding atmosphere and is subjected to nitriding treatment. The concn. of hydrogen sulfide at the time of sulfurizing treatment is set to 30 to 300 ppm, and, on the other hand, the concn. of oxygen at the time of the sulfurizing treatment and the nitriding treatment is set to <=150 ppm.
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