| 摘要 |
PROBLEM TO BE SOLVED: To produce soft-nitrided parts having excellent fatigue resistance and wear resistance and to provide a method for producing a steel for soft- nitriding excellent in machinability to form into the stock thereof. SOLUTION: The method for producing a steel for soft-nitriding excellent in machinability is the one in which a steel having a chemical compsn. contg., by weight, 0.15 to 0.45% C, 0.05 to 0.5% Si, 0.2 to 2.5% Mn, 0.002 to 0.2% S, 0.5 to 1.5% Cu, 0.25 to 0.75% Ni also so as to satisfy 1.8<=Cu/Ni<=2.2, 0.5 to 2% Cr, 0.05 to 0.5% V, 0.04 to 1.0% Ti, 0.01 to 0.3% Al, <=0.008% N, 0 to 0.3% Mo, 0 to 0.5% W, 0 to 0.3% Pb, 0 to 0.01% Ca, and the balance Fe with impurities, having the maximum diameter of Ti carbon sulfide in the steel regulated to <=10μm, and its amt. regulated to >=0.05% by cleanliness is subjected to hot working and is thereafter subjected to spheroidizing to regulate its hardness to Hv<=180, which is then subjected to cold working to regulate its hardness to Hv>=250. The soft-nitrided parts are the ones in which the steel for soft-nitriding produced by the above method is used as the stock, the surface hardness after soft-nitriding is regulated to Hv>=600, and the effective hardening depth is regulated to >=0.1 mm.
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