| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a steel component having superior indentation resistance, such as the gear, the shaft and the bearing of an automobile, by ultra-fining crystal grains of and removing a surface defect on a steel material. SOLUTION: The steel material contains, by mass%, 0.80 to 1.20% C, 0.05 to 2.00% Si, 0.10 to 2.00% Mn, 0.030% or less P, 0.030% or less S, 5.0% or less Ni, 6.0% or less Cr, 2.0% or less Mo, 0.005 to 0.05% Al, 0.0130% or less N, further contains one or both of 0.05 to 0.20% Ti and 0.02 to 0.20% Nb, and the balance Fe with unavoidable impurities. The method for manufacturing the steel component having superior indentation resistance comprises the steps of: forming the steel material into the component shape; quenching the component; further repeatedly quenching the component by direct quenching or induction hardening to refine former austenite crystal grains into a size of No. 11 in JIS G0551 or finer; tempering the component; and then polishing the surface of the component. COPYRIGHT: (C)2009,JPO&INPIT
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