Effects of Repeated Shot Peening on Microstructure and Residual Stress

Shot peening is used ubiquitously in the aerospace industry to improve fatigue capability by imparting compressive residual stresses in metal hardware. Repair processes for this hardware often necessitate local blending, and thus removal of compressive residual stresses. Re-peening can restore these beneficial residual stresses, but it is difficult to limit application to blended areas alone, leading to certain areas of hardware being peened multiple times. This presentation explains how residual stress and microstructure are modulated by repeated shot peening.