Dependence of fatigue limit on step height for stepped 0.45% carbon steel with singular stress field

A method was proposed for evaluating the relationship between the fatigue limit and the step height for a stepped plate with a sharp corner. With reference to a small crack size dependence of fatigue limit, step heights were divided into three levels, and a new evaluation method was proposed for representing the singular stress field intensity around the corner tip. An intensity factor of the singular stress field of the corner was introduced and correlated with the step height. The fatigue limit for stepped plates was represented by the threshold value of the range of the intensity factor. Moreover, the fatigue limits for extra-low stepped plates and high stepped plates, which could not be directly measured, were estimated based on the fatigue phenomena at these conditions.