Abstract
In order to estimate the fatigue lives of various machine parts, it is important to get the S-N diagrams of steels, particularly those of various casehardened steels which are used often for the principle elements of these machine parts, for example gears, axles, and so on. In this study, a general method to get the S-N diagrams graphically from the hardness and residual stress distributions was proposed. It was clarified that the proposed method was appropriated from the results of fatigue tests on S15C, S45C and SCM435 specimens with tufftriding treatment.
