Patent ID: 8573081

Claim:
A shaft part, formed with a rolling groove on which rolling elements roll, comprising: at least the rolling groove is induction hardened and has no generation of black colored oxidized scale after the induction hardening, a surface of the induction hardened rolling groove is used, as a rolling surface immediately after the induction hardening process; the shaft part is carbon steel including carbon content of 0.47-0.6 wt % and Si of 0.02-0.1 wt %, Cr of from 0.02 to <0.05 wt %, B of 0.0003-0.006 wt %; surface roughness Ra of the induction hardened surface, of the rolling groove, immediately after the induction hardening process, is less than 1.0, and a ratio of effective hardened depth of a hardened layer is about 0.15 to about 0.45.