BEARING MEMBER EXCELLENT IN CHARACTERISTIC OF RETARDING MICROSTRUCTURAL CHANGE DUE TO REPEATED STRESS LOAD AS WELL AS HEAT TREATMENT PRODUCTIVITY

摘要

PURPOSE: To provide a bearing member, in which heat treatment decarburized layer is inhibited and rolling fatigue life is improved, by specifying the chemical composition of a steel material and controlling the amount of retained austenite in a structure. ;CONSTITUTION: This steel material consists of, by weight, 0.5-1.5% C, 0.05-1.O% Nb, 0.001-0.015% Sb, ≤0.0020% O, and the balance Fe with inevitable impurities and can further contain one or ≥2 kinds selected from 0.05-0.5% Si, 0.05-2.0% Mn, 0.05-2.5% Cr, 0.05-0.5% Mo, 0.05-1.0% Ni, 0.05-1.0% Cu, 0.0005-0.01% B, 0.005-0.07% Al, and 0.0005-0.012% N. Moreover, a steel structure in which the amount of retained austenite in the steel is regulated, by volume ratio, to 10-35% is formed. By this method, heat treatment decarburized layer can be inhibited by the effect of Sb addition and a microstructural change due to repeated stress load in a bearing member can be retarded by the effects of the combined addition of V and Sb and the amount of retained austenite, and rolling fatigue life can be improved.;COPYRIGHT: (C)1995,JPO