635 高炭素クロム鋼の超長寿命疲労特性に及ぼす残留応力の影響  [in Japanese] Influence of Residual Stress on Super-Long Life Fatigue Properties of High Carbon Chromium Bearing Steel  [in Japanese]

In order to investigate the fatigue properties of high strength steels and surface hardened steels in the super-long life range (N&ge1×(10)^7), cantilever type rotating bending fatigue tests were carried out for the SUJ2 high carbon chromium bearing steel which was finished by the electro-polishing. The surface of notch bottom was removed up to 30μm deep by electro-polishing because the depth of residual stress in the notch bottom of grinding specimen has been 20μm. As a result of fatigue tests, in the case of "surface crack origin type fracture", it was found that the fatigue life of eletctro-polishing specimen were shorter than that of grinding specimen. In the case of "interior crack origin type fracture", it was found that the fatigue life of electro-polishing specimen were almost equal to that of grinding specimen. The causes for this are discussed.