| 摘要 |
PROBLEM TO BE SOLVED: To improve the strength of tooth surface against peeling damage by forming an abnormally carburized layer of prescribed depth uniformly in the tooth surface. SOLUTION: A reinforced gear is constituted of a case hardening steel stock having a chemical composition which consists of, by weight, 0.10-0.30% C, 0.01-0.50% Si, 0.60-2.00% Mn, <=0.025% P, <=0.040% S, <=2.00% Cr, 0.020-0.080% Nb, 0.0010-0.0100% B, <=0.010% N, <=0.100% Ti, and the balance Fe and in which the total content of Si, Mn, and Cr is regulated to 1.90-4.50%. By applying carburizing and quenching to this gear, a uniform abnormally carburized layer 11 of 20-30μm thickness L1 can be formed in the tooth surface.
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