STEEL FOR CARBO-NITRIDING BEARING

摘要

PROBLEM TO BE SOLVED: To produce a steel for a carbo-nitriding bearing having a long rolling fatigue service life at a high yield by subjecting a steel contg. a specified small amt. of Cr and furthermore contg. one or more kinds among Ni, Mo and Cu to carbo-nitriding treatment and prescribing the content of (C+N) to a specified depth from the surface. ;SOLUTION: The surface of a steel having a compsn. contg., by weight, 0.10 to 0.30% C, 0.35% Si, 0.8% Mn and 1.5 to 2.5% Cr so as to regulate the content of Cr+Si to 1.8 to 2.8% or furthermore contg. one or more kinds among 3.0% Ni, 1.0% Mo and 1.0% Cu is subjected to carburizing treatment, is thereafter subjected to nitriding treatment in an NH₃ atmosphere and is successively subjected to quenching and tempering treatment. The content of (C+N) to a depth of 0.1mm from the surface is regulated to 1.0 to 2.0%, and the content of the residual austenite in the surface layer is regulated to, by volume, 40 to 65%. The steel for a car-nitriding bearing in which the Vickers hardness to a depth of 50μm from the surface is regulated to 400 to 700, small in dispersion and having a long rolling fatigue service life can be produced at a high yield.;COPYRIGHT: (C)1998,JPO