Gradual changes in residual stress and microstructure during contact fatigue in ball bearings

Abstract

Deep-groove ball bearings have been endurance tested at high stress levels. The purpose of the work was to study the simultaneous generation of residual stresses and occurrence of structural changes owing to cyclic rolling contact fatigue. During the investigation the decomposition of both retained austenite and parent martensite were followed. The residual stresses and the austenite decomposition were measured by an X-ray diffraction technique, using signal averaging. Optical and transmission electron microscopy were used to observe the transformed regions resulting from the martensite decay. Depth profiles of residual stress and of successive structural changes were constructed. The observations are discussed in terms of a qualitative model for residual-stress generation under cyclic rolling contact.