Experimental study of the microstructure and stress state of shot peened and surface mechanical attrition treated nickel alloys

The efficacies of shot peening (SP) and surface mechanical attrition treatment (SMAT) in inducing multiple changes in the microstructure and stress state of the workpiece are compared experimentally, for the first time, using depth-profile X-ray diffractometry. SMAT generates a thicker nanocrystalline surface layer, a deeper plastically deformed zone and a thicker surface region with larger residual compressive stresses than SP. These results can have important implications for improving the fatigue life and wear resistance of metals in the future.