| 摘要 |
PROBLEM TO BE SOLVED: To produce soft-nitrided parts showing excellent fatigue resistance and wear resistance and to provide a method for producing a steel for soft intruding excellent in cutting performance as its stock. SOLUTION: (1) A steel having a chemical compsn. contg., by weight, 0.15 to 0.45% C, 0.10 to 0.50% Si, 0.2 to 2.5% Mn, 0.002 to 0.2% S, 0.5 to 2% Cr, 0.05 to 0.5% V, 0.04 to 1% Ti, 0.01 to 0.3% Al, <=0.08% N, 0 to 0.35% Pb, 0 to 0.01% Ca, and the balance Fe with impurities, in which the maximum diameter of Ti carbosulfides in the steel is regulated to <=10μm, and the quantity thereof is regulated to >=0.05% by cleanliness is subjected to how working and is thereafter subjected to spheroidizing to regulate its hardness to Hv<=180, which is next subjected to cold working to regulate its hardness to Hv>=250. (2) The chemical compsn. of the steel stock may contain one or more kinds of 0.02 to 0.3% Mo and 0.04 to 0.5% W, where the ones other than 0.05 to 0.50% Si are left as they are as prescribed in (1). The soft-nitrided parts are the steel for soft-nitriding whose stock is produced by the above method, whose surface hardness after soft-nitriding is regulated to Hv>=600, and whose effective hardening depth is regulated to >=0.1 mm.
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