Effects of laser shock processing and shot peening on 253 MA austenitic stainless steel and their consequences on fatigue properties

Abstract

A comparative study of the influence of laser shock peening without coating (LSPwC) and shot peening (SP) treatments on the low cycle fatigue life of 253 MA austenitic stainless steel was investigated. LSPwC treatments were performed with 2500 pulse/cm2 and 5000 pulse/cm2. To evaluate the effects of each treatment, residual stress, roughness, hardness, and microstructure were analyzed. It is of particular interest the correlation of the fatigue performance with the dislocation microstructure evolution. The results reveal that all the surface treatments increase the surface hardness, induce compressive residual stresses (CRS) and a high density of mechanical twins and dislocations. The stability of the workhardened near surface microstructure results in the improvement of the fatigue life of peened 253 MA. Moreover, the best improvement of fatigue life reached for SP is mainly due to the highest number of twins and the more superficial CRS.