Influence of Stress Ratio and Contact Pressure on Fretting Fatigue Behavior of Modified 9Cr-1Mo Steel

Influence of contact pressure and maximum cyclic stress (σmax) on the fretting fatigue behavior of modified 9Cr-1Mo steel has been studied using contact pads made of the same steel. The contact pressure was varied from 50 to 200 MPa using σmax of 400 and 500 MPa at a stress ratio (R) of 0.1. The fatigue life was observed to decrease in the presence of fretting action. For a given σmax the fretting fatigue life of the steel decreased with an increase in contact pressure up to 100 MPa beyond which saturation was observed. The ratio of slip to stick area increased with the contact pressure. This is in agreement with the increased depth of the fretting-induced debris and roughness.