Patent ID: 6325867
Filing Date: 2001-12-04
Classification: C21D,C23C,F16C,Y10S,Y10T

Abstract:
A rolling bearing comprising components of an inner race, an outer race and a plurality of rolling elements, at least one of the components being made from an alloy steel comprising 0.1 wt % up to 1.2 wt % of carbon and the balance being Fe, the one of the components having a hardened layer with a grinding allowance portion after being subjected to carbonitriding and hardening heat treatments, followed by grinding the grinding allowance portion to obtain a finished component part having a surface layer which removes the grinding allowance portion from the hardened layer,wherein said surface layer comprises:carbon in a range from 0.9 wt % up to 1.6 wt %;nitrogen in a range from 0.05 wt % up to 0.3 wt %;said nitrogen content being at least 0.05 wt % at a depth of 2% of a diameter of the finished component part inwardly from a surface of the surface laver; anda nitrogen gradient, which is the rate of change in the concentration of nitrogen in the depth direction of said surface layer, not exceeding 0.5 wt %/mm.