Experimental Reconfirmation of Characteristic S-N Property for High Carbon Chromium Bearing Steel in Wide Life Region in Rotating Bending
Tatsuo Sakai, Mitsuhiro Takeda, Kazuaki Shiozawa, Yasuo Ochi, Masaki Nakajima, Takashi Nakamura and Noriyasu Oguma
Abstract:In fatigue tests of high strength steels and surface hardened steels, a characteristic fatigue behavior such that S-N curve tends to come down again in the long life region of N>107 was often observed and reported by many researchers. When the mechanical design is based on the fatigue limit of the material, the above aspect introduces a typical difficulty to provide the reliability of the mechanical structures. In order to clarify such S-N characteristics in wide life region, a series of fatigue tests were performed by means of same type fatigue testing machines and same type of fatigue specimens in a definite high carbon chromium steel for the use of bearing as a collaborative study by the authors. Thus the complicated S-N property of this steel was tentatively interpreted as duplex S-N characteristics given by superposition of S-N curves for the respective fracture modes of the surface-originated fracture and the inclusion-originated fish-eye fracture. Key Words:High carbon chromium steel, Long life fatigue, Duplex S-N property, Fatigue limit