高炭素クロム軸受鋼の広寿命域における特徴的回転曲げ疲労特性に関する実験的検証

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.