Effects of Laser and Shot Peening on Fatigue Crack Growth in Friction Stir Welds

The effects of laser, and shot peening on the fatigue life of Friction Stir Welds (FSW) have been investigated. The surface roughness resulting from various peening techniques was assessed, and the fracture surfaces microstructure was characterized. Laser peening resulted in an increase in fatigue life approximately 60%, while shot peening resulted in 10% increase when compared to the unpeened material. The surface roughness of shot peening was significantly higher compared to the base material, while specimens processed with laser peening were relatively smooth.