| 摘要 |
PURPOSE:To obtain a product which has less strain and has no local variance in the strength of the core part in the stage of subjecting a case hardened steel contg. specific ratios of C, Si, Mn, Cr, solAl, and N to carburization hardening by subjecting said steel to a heat treatment under a specific condition. CONSTITUTION:A case hardened steel contg., by weight %, 0.10-0.30% C, 0.03- 0.50 Si, 0.30-1.80% Mn, 0.015-0.600% solAl and 0.005-0.025% N, contg. 0.05- 0.35% Mn if necessary, and contg. further 1 or >=2 kind among 0.04-0.40% S, 0.05-0.40% Pb, 0.005-0.20% Bi, 0.005-0.20% Te, and 0.001-0.0020% Ca according to need and consisting of the balance Fe and unavoidable impurities is once held for 2-5hr in the temp. region of 600-Ac1 transformation point in the midway of heating for the purpose of treatment and is then heated as it is, by which the prescribed treatment is accomplished in the stage of subjecting said steel to a carburization hardening treatment. |
