Influences of surface roughness and residual stress on fatigue life of ground steel components

Abstract

An experimental study of the residual stresses and fatigue properties of ground En 31 steel specimens is described. The individual grinding parameters (wheel types and speed, feed, dressing, and lubricant) are grouped into three categories: abusive, conventional, and gentle grinding. In the absence of high temperature-gradients, the mechanical strain in the workpiece is dominant, giving small compressive residual stress and long fatigue life. It is more common, however, for high temperatures to be generated at the surface. Quenching of the bulk steel produces martensite, which is then tempered, and the accompanying volume change can leave high tensile stress in the surface, resulting in greatly reduced fatigue life. Surface roughness is found to be much less important than the residual stress.