The fatigue characteristics of Plasma Nitrided three Pct Cr-Mo steel

The plasma nitriding conditions necessary to treat a three pct Cr-Mo steel with and without the formation of a surface compound layer have been investigated and the influence of this compound layer on the fatigue limit is described. The nitrided case depth has been varied as a function of time at a constant temperature of 480 °C and the corresponding rotating bending fatigue strength evaluated. This data has been used to develop a simple model to describe the influence of the case depth on the fatigue limit.