Residual Stress Relaxation of Shot-Peened Deformation Surface Layer on Duplex Stainless Steel Under Applied Loading

Abstract

The relaxation of residual stress in shot-peened surface layer of duplex stainless steel S32205 under static and cyclic loading was investigated. The results reveal that the compressive residual stress is relaxed under applied tensile stress. The relaxation of residual stress in longitudinal direction is more obvious than that in transverse direction in both austenite and ferrite. When the applied stress is beyond the yield strength of the materials, the relaxation of the residual stress becomes drastic. Under cyclic loading, the residual stress relaxation occurs fast in the first few cycles, it then becomes stable gradually. A model was used to quantitatively calculate the residual stress under cyclic loading with different applied tensile stresses. The relaxation behavior is determined by the applied loading, the number of cycles, dislocation density, and the residual stress gradient. The relaxation behavior difference under cyclic loading between ferrite and austenite is discussed.