Fatigue Life Prediction for Bearing Steel Failed with Fish-Eye at Subsurface in Rotating Bending
Noriyasu OGUMA and Tatsuo SAKAI
Abstract:Cantilever-type rotating bending fatigue tests were carried out on high carbon chromium bearing steel in air at room temperature. Concerned with the subsurface fracture type specimens, the fatigue lives were related to three factors which are the stress amplitude at nonmetallic inclusion, the inclusion size and the granular fracture surface size around inclusion. That is, these factors can be connected to the parameters in the equation of Paris' law. Thus, crack propagation lives at flat fracture surface in fish-eye region were analyzed using fracture mechanics. It was found that the period forming granular fracture surface occupied more than 90% of the total fatigue life. It was another finding that effective factors to expand the fatigue life of this steel were smallness of the inclusion size and high value of the matrix fracture toughness. Key Words:Fatigue, Nonmetallic inclusion, Subsurface fracture, Bearing steel, Fish eye