To provide a rolling member for a needle roller bearing, which has the long life even in a hostile environment, while containing a controlled amount of an alloy element, and to provide a needle roller bearing.
A bearing ring 11 and a needle roller 13 of a thrust needle roller bearing 1 are formed of a steel including 0.3 to 0.4% carbon, 0.3 to 0.7% silicon, 0.3 to 0.8% manganese, 0.5 to 1.2% nickel, 1.6 to 2.5% chromium, 0.1 to 0.7% molybdenum, 0.2 to 0.4% vanadium, while containing silicon+manganese controlled to 1.0% or less, nickel+chromium controlled to 2.3% or more and chromium+molybdenum+vanadium controlled to 3.0% or less, and the balance iron with impurities; wherein a hardened layer is formed thereon. The surface layer of the hardened layer has a hardness of 725 to 800 HV, and contains carbides which have the maximum particle size of 10 m or smaller and occupy 7 to 25% or less by an area rate. The inner part of the hardened layer has a hardness of 450 to 650 HV.
Toshio Morita
Yoshihei Nakamura
Yutaka Horii
Hisato Noda
Masayuki Sakai
Nobuo Arakawa