Evaluation of maximum inclusion size and fatigue limit for high strength steel in rotating rending

Based on the observation of fracture surfaces for a low-alloy high strength steel under rotating bending in very high cycle regime, a newly defined method about inspection plane under rotating bending was developed in this paper. By using the statistics of extreme values (SEV) method, the maximum sizes of inclusion and FGA corresponding to the control volume of specimen are evaluated to be about 41.38 μm and 58.51 μm on the basis of this newly defined inspection plane, and the corresponding values of fatigue limit are evaluated to be 690 MPa and 654 MPa, respectively. It should be noted that fatigue design based on former involves a certain amount of risk in very high cycle regime.