| 摘要 |
PURPOSE:To obtain a high-strength steel for gears having superior bearing strength, by subjecting a steel having a composition consisting of C, Si, Mn, Ni, Cr, Mo, Nb, and Fe to carburizing and carbonitriding treatments under specific conditions and then to hardening. CONSTITUTION:The steel consisting of, by weight, 0.15-0.30% C, 0.85-1.50% Si, 0.40-1.30% Mn, <=3.00% Ni, 0.90-2.00% Cr, <=4.00% Mo, 0.02-0.10% Nb, and the balance Fe with inevitable impurities is subjected to carburizing treatment at 900-950 deg.C and successively to carbonitriding treatment at a temp. regulated to 800-900 deg.C for preferably about 1-2hr, followed by hardening. In this way, a thin layer containing large amounts of residual austenite is formed on the part in the vicinity of surface, so that high-strength steel for gears can be obtained.
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