| 摘要 |
PURPOSE:To prolong rolling contact fatigue life even under severe conditions by specifying respective contents of C, Si, and Cr in a high-carbon chromium- type bearing steel with a specific composition to improve hardness and tempering softening resistance. CONSTITUTION:This high-carbon chromium-type bearing steel has a composition consisting of, by weight, 1.1-1.5% C, 1.0-2.0% Si, 0.7-1.3% Cr, 0.2-1.0% Mn, and the balance Fe. In this steel, hardness can be improved by increasing C content to increase the amount of carbide in a matrix, but spheroidizing of carbide becomes difficult when Co content exceeds the upper limit. As to Si content, an effect of improving deformation resistance under high load cannot be produced when it is below the lower limit and, on the other hand, cold workability is deteriorated when it exceeds the upper limit. Moreover, the control of heat treatment conditions is made difficult because of deterioration in hardenability and reduction in residual carbide when Cr content is below the lower limit, and further, since carbide is liable to occur and macrocrystalline carbide is formed because of increased C content and, as a result, service life is shortened when Cr content exceeds 1.3%, the upper limit of Cr content is regulated to 1.3%. |
