US Patent 7435308 Rolling bearing

An inner ring 2 and an outer ring 3 of a rolling bearing 1 are made from steel that contains carbon in the range of 0.65 to 1.25% by mass, silicon in the range of 0.7 to 2.5% by mass, manganese in the range of 0.1 to 1.5% by mass, chromium in the range of 0.5 to 3.0% by mass, 1.5% by mass or less of molybdenum, 9 ppm or less of oxygen, 30 ppm or less of titanium, and 80 ppm or less of sulfur, and whose rating number of the Thin type A series inclusion is 1.5 or less and that of the Heavy type A series inclusion is 1.0 or less when the rating numbers are measured by a method stipulated in ASTM E45.