Effect of Applied Stresses and Stress Gradients on Residual Stresses in Shot Peened Superalloys

Shot peening is a commonly used surface treatment process to impart large

compressive residual stresses at the surface of components to mitigate fatigue damage.

This process also generates sub-surface tensile residual stresses required to satisfy load

equilibrium. This balance of compressive surface residual stress and tensile interior

stress is held in place by the localized plastic deformation associated with shot peening.

Additional plastic deformation typically from applied stresses and stress gradients (e.g. at

notches), will redistribute this balance of compressive and tensile residual stresses. In

this study, smooth and notched IN100 superalloy specimens were shot peened and

subjected to a variety of applied stresses. X-ray diffraction technique was used to

determine the redistributed residual stress depth profile. This study describes a series of

experiments combined with elastic-plastic finite element analyses to explain

redistribution in residual stress depth profiles subject to applied stresses and stress

gradients in IN100 shot peened specimens.