The influence of shot peening process on the residual stress and microstructure in deformed surface layer of S30432 austenitic stainless steel

Shot peening is an important surface treatment which can induce compressive residual stress and refine microstructure in the deformed surface layer. In this paper, the traditional shot peening, dual shot peening and triple shot peening have been applied to S30432 austenitic stainless steel. The residual stress and microstructure in the deformed layer were investigated by X-ray diffraction method. The results revealed that a compressive residual stress field was induced in the deformed layer for all shot peening conditions. As the shot peening step increased, the compressive residual stresses increased in near surface layer, and then deceased faster in deeper deformed layer. In terms of microstructure, the domain size increased, while the micro-strain decreased with the depth increasing in the deformed layer. Compare with the effect of three different shot peening method, triple shot peenng is more effective to optimize the compressive residual stress, microstructure and micro-hardness of S30432 austenitic stainless steel.