METHOD FOR PRODUCING STEEL PART HAVING LONG ROLLING CONTACT FATIGUE LIFE

摘要

The present invention provides a steel part having a long rolling contact fatigue life and capable of further increasing the life of a bearing under severer using condition than usual conditions. Specific resolving means is as follows: A steel part including steel having a composition containing 0.7% by mass to 1.1% by mass of C, 0.5% by mass to 2.0% by mass of Si, 0.4% by mass to 2.5% by mass of Mn, 1.6% by mass to 5.0% by mass of Cr, 0.1% by mass to less than 0.5% by mass of Mo, 0.010% by mass to 0.050% by mass of Al, less than 0.0015% by mass of Sb as an impurity, and the balance composed of Fe and inevitable impurities, the steel being hardened and tempered. In the steel structure of a portion from the surface to a depth of 5 mm, residual cementite has a grain diameter of 0.05 to 1.5 µm, prior austenite has a grain diameter of 30 µm or less, and the ratio by volume of the residual austenite is less than 25%.