What can micromechanics tell us about the surface integrity of shot-peened materials?

Standard techniques for assessing shot peening include XRD and EBSD for measuring residual stresses and severe deformation beneath the surface; however, these techniques do not consider the localised micromechanical behaviour. Here, single-grain micropillar compression tests in a Ni-base superalloy reveal that the micromechanical effect of shot peening could be insignificant due to the machining-induced pre-strained condition of the surface. Further, it is shown that shot-peening-induced strengthened layer can extend much less (∼50%) than the depth at which compressive stresses are still present. This work highlights the need for employing micromechanics as a complementary shot peening assessment technique for machined components