Effect of shot peening on fatigue performance of austenitic stainless steels

Fatigue is a predominant failure mode, which occurs in metallic structural components subjected to normal working conditions. Surface strengthening methods are of importance to enhance fatigue performance of these components. However, under cyclic loading, the gradient structure produced by surface strengthening methods can encounter instability and thus, decreasing fatigue performance. Thus, the present work is aimed to investigate the main contributing factor to fatigue performance enhancement by assessing the stability of shot peening–produced attributes of a gradient structured 316 austenitic stainless steel under cyclic loading. The results show that the peened specimen with superior surface quality and near surface layer property has the highest relaxation rate of residual stress. Nevertheless, it has the highest fatigue life improvement. This is attributed to the fatigue-induced near-surface microstructural stability resulted from the presence of peening-produced surface plastic deformation uniformity and near-surface microstructural complexity, which allow accommodating the plastic strain accumulated during cyclic deformation.