Rolling contact fatigue of case-hardened chromium steel

The rolling contact fatigue of case-hardened steel surfaces in lubricated heavily loaded contact was studied. Three different case-hardening treatments were tested with a ratio of slide to roll of ?5%. Other ratios of slide to roll were used to determine the effect of tangential traction on the rolling contact fatigue endurance. When the actual contact width was measured after testing, the scatter of the fatigue results was reduced. The depth of the maximum plastic strain was determined by measuring the hardness before and after testing and was found to correspond to the occurrence of the lowest ratio of the critical shear stress to the amplitude of the load-induced orthogonal shear stress. The role of residual stresses in rolling contact fatigue is discussed. It was found that a more detailed knowledge of lubricant behaviour in heavily loaded contacts is needed to reveal the true distribution of tangential traction on the contact surface. This affects the angle of the plane and the value of the maximum amplitude of the shear stress beneath the contact zone.