| 摘要 |
There is disclosed a bearing member which is enhanced in toughness without lowering the hardness of a core portion so as to prevent an instantaneous rupture of the bearing member, and is excellent in rolling fatigue service life characteristics. Martensitic Fe-based bearing steel of the invention contains, by weight, not more than 0.4% carbon, not more than 2% silicon, not more than 2% manganese, not more than 5% nickel, 3.5 to 7.0% chromium, at least one of tungsten and molybdenum an tungsten equivalent defined by ([W]+2[Mo]) of which at least one is 3 to 15%, and not less than 0.5% but less than 1.1% vanadium. A ratio of Cv/Ceq is not more than 0.3 where Cv represents a carbon equivalent of vanadium defined by 0.2[V], and Ceq represents a carbon equivalent of carbide-forming elements defined by (0.063[Cr]+0.06[Mo]+0.033[W]+0.2[V]). With this construction, the precipitation of MC carbides is suppressed, and M2C-type carbides larger in morphology than MC-type carbides are dispersed in an appropriate amount, thereby enhancing a rupture toughness value.
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