Patent ID: 7422643

Claim:
A rolling element which is made from a steel material comprising at least 0.1 to 0.45 wt % C and 0.3 to 1.5 wt % Cr, and optionally 0.1 to 0.5 wt % V, wherein the carbon concentration of a rolling contact surface is 0.6 to 1.5 wt % and the depth of an area having a carbon concentration of 0.45 wt % or more is 0.4 mm or more below the surface by carburizing or carbonitriding, wherein said rolling element having a rolling contact surface layer having a case-hardened layer being formed by induction heating and subsequent cooling of said rolling contact surface, said case-hardened layer having a structure tempered at low temperature in which 2 to 18% by volume of a cementite compound is dispersed in a martensite parent phase containing 0.25 to 0.8 wt % carbon solid-dissolving therein, and wherein the average Cr concentration of the cementite compound which is dispersed in the case-hardened layer of the rolling contact surface layer is 2.5 to 10 wt % being formed by a Cr incrassating treatment step.