Effect of the residual stress induced by surface severe plastic deformation on the tensile behavior of an aluminum alloy

Surface severe plastic deformation (SSPD) improves the mechanical behaviors of materials by generating non-uniform, heterogeneous microstructures on their surfaces. SSPD enhances the mechanical properties of the material, such as resistance to fatigue and yield strength. Herein, a decrease in the yield strength after SSPD, which is contrary to the findings of previous studies that report increased yield strengths, was considered. The main cause of this phenomenon was the internal tensile residual stress, which was inevitably induced by the surface compressive residual stress during SSPD. The inherent residual stress after SSPD was measured and applied in a tensile study of a real Al alloy to verify the phenomenon. Finally, the effects of the residual stress on the tensile mechanical properties were analyzed via analytical and numerical methods. Moreover, the transient behavior in the early stage was determined based on residual stress.