Abstract
The effects of surface roughness on low cycle fatigue properties were investigated by strain-controlled fatigue tests using specimens of austenitic stainless steel finished by two different methods: machining and mirror polishing. During fatigue tests, the surface roughness of each specimen was measured, and crack initiation and propagation were observed using cellulose acetate replicas. As a result, the fatigue life of mirror polished specimen was longer than that of machined one. It was shown that the surface roughness affected the fatigue life. The change of surface roughness of each specimen showed the same increasing tendency with respect to the number of cycles. However, around the end of fatigue life, the surface roughness of mirror polished specimen became larger than that of machined one. In the damage process, the crack initiated at the very early stage of fatigue life. The crack growth rate was small until the middle of fatigue life; however, it increased rapidly after that. The surface roughness affected the crack initiation, and that is the reason why the fatigue life and the change of surface roughness were different between each specimen.
