METHOD FOR HEAT TREATMENT OF STEEL

摘要

There is provided a rolling bearing which has long life against rolling fatigue and exhibits no decrease in fracture strength and no increase in rate of dimensional change over time, even if the part size thereof is large, and which can obtain higher strength by crystal grains being further refined, if it has a size equal to or smaller than a prescribed size. The rolling bearing according to the present invention includes a race and a rolling element. At least one member of the race and the rolling element has a nitrogen-enriched layer in its surface layer, and a surface layer portion contains austenite crystal grains having a grain size number of at least 11. The member has hardenability allowing a position exhibiting HRC50 in a hardenability test method for steel to be apart from a quenched end by a distance of at least 12.7 mm (8/16 inch).