In this study, the effect of surface condition on small fatigue crack initiation and growth of austenitic stainless steel was investigated. In constant strain range tests, surface roughness depended on strain range. Two step variable amplitude straining tests were performed to reveal the effect of surface roughness on fatigue crack behavior. Surface roughness was affected from experimental condition. Typically, when lower strain range was applied after higher strain range, surface roughness was larger than that of constant strain range tests. The relationship between crack growth rate and J integral range of two step variable amplitude straining tests was similar to that of constant strain range tests. Fatigue tests were conducted for specimen with machined surface, there are many scratches developed by turning. Fatigue crack was initiated from the scratch. Microstructure of turned specimen was observed by electron back scatter diffraction method. Surface roughness was approximately constant during fatigue life for as-machined and grinded specimen while it increased gradually for electro-polished specimens. Crack growth characteristics were coincided regardless of machined condition, and thus fracture mechanics approach was available to predict the fatigue lives.
