Laser Shock Peening at Oblique Angles

Laser shock peening process generally introduces compressive residual stresses on a component by targeting laser beam normal to the surface. However, geometrical complexity of components necessitates laser beam to be delivered at an angle other than normal. In such cases, the peening effect is not optimal. In this study, the effect of varying incident angles on residual stresses of Ti-6Al-4V components after laser shock peening is investigated. The results revealed a decrease in residual stress magnitude and depth with an increase in incident angle. The degree of reduction is especially obvious when the angle exceeds 20°. Peening at a constant laser fluence produced similar levels of residual stress as in normal peening. However, at very large angles, peening effect was still slightly lower despite using same fluence, possibly due to other losses. It was found that increasing the laser fluence can compensate for the reduction in peening effect at large angles.