Effect of prestress state on surface layer characteristic of S30432 austenitic stainless steel in shot peening process

Residual stress and microstructure on surface deformed layer of S30432 austenitic stainless steel after shot peening with different prestress states were investigated. The domain size and micro-strain in the deformed layer were analyzed by Voigt method. The results showed that the compressive residual stress and microstructure were improved significantly after stress shot peening. The values of compressive residual stress depended on both the prestress state and the measurement directions. Microstructure investigations revealed that smaller domain size and higher micro-strain were induced compared with the conventional shot peening. And the variations of microstructure were mainly influenced by the values of prestress state. Based on these investigations, it is concluded that stress shot peening is superior to conventional shot peening and it is an effective method to improve the surface properties of S30432 austenitic stainless steel.

► The stress shot peening is superior to the conventional shot peening.
► The prestress state and measurement directions could greatly influence the residual stress.
► Residual stresses along the loaded direction are bigger than other directions.
► Higher prestress lead to smaller domain size, high density of dislocation.