Changes in residual stress and successive observations in the fatigue test of workhardened mild steel

摘要

In this paper, the changes in the residual stress of prestrained or shot-peened carbon steel specimens in the fatigue process were measured by the X-ray diffraction method, and the behavior of slip band initiation and crack initiation in the early fatigue process was investigated by successive observations of replicas of the specimen surface, using an optical microscope and an electron microscope. The residual stress of both prestrained and shot-peened specimens decreased rapidly in the early stage of the fatigue process, and then remained constant up to fracture. The behavior of slip band and crack initiation in the prestrained and shot-peened specimens is similar. In these two kinds of specimens, many slip bands and cracks originated within grains rather than along the grain boundary.