The contact fatigue behavior of PM steels

The aim of this work is to determine the safe working conditions of PM steels in order to avoid damage caused by rolling contact fatigue (RCF). To avoid the possible damage on the material, any pit formation on the surface or crack nucleation in the subsurface should be prevented. RCF crack promotes by plastic deformation in the subsurface layers and the plastic deformation occurs when the applied stress is higher than yield strength of the material. By considering this relation as a base of an approach, a mechanical model was proposed which gives an overview for the possibility of the crack nucleation in the mechanism for a specific case by highlighting the role of different conditions such as Hertzian pressure and the property of the materials such as density, microhardness, carbon content, surface treatment etc. All the predictions from the model were confirmed by performing experimental tests in different conditions.