Influence of residual stress and mean stress on fatigue strength improvement of austenitic stainless steel

This paper refer to the effect of compressive mean stress, work-hardening, microstructure improvement and compres- sive residual stress generated by roller-working on fatigue properties of austenitic stainless steel. Pulsating fatigue tests have been performed on the specimens with and without surface deformation. The results showed that high compressive mean stress specimens have higher fatigue strength than that of low compressive mean stress ones. Surface replica observation results show that compressive mean stress is responsible for delaying of fatigue crack initiation and preventing fatigue crack propagation. In case of 1 mm rolled specimen, after roller-working the fatigue limit of the specimen increases by 196%. Work-hardening, resid- ual stress and microstructure improvement are the most responsible for the fatigue strength improvement of rolled specimens. Compressive residual stress induced by roller-working has the same effect of compressive mean stress on improving fatigue limit as proved under the modified Goodman diagram. Under the fatigue limit diagram, it could be seen that the effect of work- hardening on fatigue limit improvement of 1 mm rolled specimen is remarkably higher than that of compressive residual stress one.