Comparison of mechanisms of advanced mechanical surface treatments in nickel-based superalloy

Mechanical surface enhancement techniques are used to introduce compressive residual stresses to enhance the fatigue life and corrosion resistance of metallic components. In this study, we compare the effects of three advanced mechanical surface enhancements treatments: laser shock peening, cavitation shotless peening and ultrasonic nano structure modification on residual stress, hardness, plastic deformation and changes in near surface microstructure introduced in a Ni-Base superalloy, IN718 SPF(Super plastic forming). Coupons of the alloy were peened using two different conditions of each treatment and results compared to achieve a better understanding of underlying mechanisms of these techniques. Results indicate that there are significant differences in mechanisms of these surface treatments leading to differences in material response.