Endurance limit prediction for sulphur-alloyed spray-formed steels

Crack initiation in fatigue specimens takes place in highly stressed regions either at the surface or in the volume. In the latter case, often inclusions are the responsible origins influencing the fatigue strength by their size and orientation: The endurance limit decreases with increasing inclusion dimensions perpendicular to the loading direction. In this paper a calculation method based on the weakest-link concept is presented which enables the prediction of the fatigue limit as well as the fracture initiation site in specimens which fail predominantly at inclusions. It considers the inclusion size distribution, the hardness and the residual stresses of the specimens.