| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a soft-nitriding non-normalizing machine part with which even the normalizing treatment is not applied after forging, but the soft-nitriding is applied, a high fatigue strength and a bending-correction can be obtained. SOLUTION: A steel containing 0.30-0.45% C, 0.1-0.5% Si, 0.6-1.0% Mn,≤0.05% P,≤0.1% S,≤.005% Al, 0.010-0.030 N, 0.005-0.05% Ti, 0.01-0.5% Mo and 0.0001-0.005% Ca, and the balance Fe with impurities, is heated to 1100-1250°C and a forging is started at≤1100°C and finished at≤800°C, and after air-cooling, without performing the normalizing treatment, the soft-nitriding is performed. Then, in the case of containing this steel to 0.35-0.45% C, 0.1-0.35% Si, 0.01-0.35 Mo, this heating can be performed at 900-1250°C. Further, according to the necessity in this steel, one or two elements of≤0.05% Nb and≤0.005% B can be contained. COPYRIGHT: (C)2008,JPO&INPIT
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