SURFACE INTEGRITY AND ITS EFFECTS ON THE FATIGUE LIFE OF THE NICKEL-BASED SUPERALLOY GH33A

This paper presents a study of the formation of surface roughness, residual stress and surface hardening produced by cutting and grinding, and then compares the different effects of surface integrity on the high-cycle and low-cycle fatigue lives of the nickel-based superalloy GH33A at room temperature and at 550-degrees-C. For the purposes of enhancing the fatigue life and reliability of machined components and controlling the machining parameters, the experimental results offer a useful reference point. It is concluded that, under the condition of low-cycle fatigue, surface roughness becomes the main factor and surface hardening has an unfavourable influence on the fatigue life, while the residual stress can be neglected because of its relaxation under the applied loads. The influence of the integrity of the surface on the high-cycle fatigue life has a different mechanism from that on the low-cycle fatigue life.