STEEL FOR CARBURIZED COMPONENT EXCELLENT IN COLD WORKABILITY, PREVENTING COARSENING OF CRYSTAL GRAINS IN CARBURIZING IMPACT RESISTANCE AND IMPACT FATIGUE RESISTANCE

摘要

PROBLEM TO BE SOLVED: To provide a steel for a carburized component, to a component produced through a spheroidizing annealing, cold forging, and a carburizing, quenching and tempering stage, while having excellent workability, in which the coarsening of crystal grains even in the subsequent carburizing is suppressed, and having excellent impact resistance and impact fatigue resistance.;SOLUTION: A steel having a composition comprising, by mass, 0.2% C, 0.1% Si, 0.4% Mn, 0.015% P, 0.015% S, 1.0% Cr, 0.0015% B, 0.15% Ti, 0.006% N, 0.030% Al, 0.1% Mo and 1.0% Ni, and the balance Fe with inevitable impurities is subjected to spheroidizing annealing, is thereafter subjected to cold forging, is subjected to mechanical working such as machining, and is subjected to carburizing, quenching and tempering, so as to obtain the steel for a carburized component in which the coarsening of crystal grains at the time of the carburizing is prevented, and having excellent impact resistance and thermal fatigue resistance without hindering its workability.;COPYRIGHT: (C)2006,JPO&NCIPI