Investigation of surface structural modifications caused by the influence of the ablative layer in Inconel718 Ni-base superalloy through laser shock peening

The use of a protective sacrificial layer adds to the overall processing cost of laser shock peening, which is an effective surface modification technique for Ni-superalloys. This study investigates the effect of this layer on the nature of residual stress, subsurface stressed depth, and microstructural differences such as grain boundary fractions and defect densities. Without the ablative layer, the subsurface exhibits predominantly compressive stress, except for the formation of a thin surface layer with tensile residual stress coupled with large textured grains.