| 摘要 |
PROBLEM TO BE SOLVED: To produce hardened parts excellent in quality characteristics by means of induction hardening. SOLUTION: A steel, having a composition consisting of, by mass, 0.5-0.75% C, 0.5-1.8% Si, 0.4-1.5% Mn, 0.019-0.05% Al, <=0.010% P, <=0.020% S, <=0.0015% O, 0.002-0.006% N, and the balance Fe with inevitable impurities, is used. A stock of this steel, in which the number and maximum size of oxide nonmetallic inclusions in the steel are <=2.5pieces/m<2> and <=19μm, respectively, is forged at a temp. in the range between (Ac3 point-100) and (Ac3 point + 200) deg.C at >=70% draft, cooled at (0.005 to 10) deg.C/s cooling rate after forging, and subjected to induction hardening and tempering treatment.
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