CPFEM investigation of effects of residual stress and work hardening on the tensile behavior of a shot peened steel

Abstract : It is generally accepted that shot peening can improve the fatigue resistance of materials. Therefore this technique and its variants are largely used in industry to strengthen critical mechanical components. This increase of material performance is thought to be mainly due to the superficial compressive residual stress and the work hardening generated during these treatments. Globally a rather good understanding of their roles in improving the material performance has been obtained. However, the majority of the studies do not take into account the fact that the residual stress and the work hardening generated by shot peening are of multiaxial nature. In this work, the effect of work hardening and compressive residual stress induced by shot peening on the tensile behavior of a stainless steel is studied using crystal plasticity finite element method (CPFEM). A phenomenological crystal plasticity model is used on a polycrystal representative elementary volume (REV) to investigate plastic activities at the slip system level under different loading conditions. Results show that the work hardening and the residual stress of different directions play different roles in determining the mechanical behavior of shot peened steel under uniaxial tensile loading. The results of numerical simulations are compared to the experimental results of tensile tests, and interpretations are given based on the plastic slip activities under different loading conditions.