Investigation on the deformation progress and residual stress of Ti-6Al-4V alloy during laser shock peening

Laser shock peening is used to impart compressive residual stress and plastic deformation in the target material, to realize the surface strengthening and improve the service performance. In the current work, the array dimples were fabricated by using square-spot overlapping laser shock, with the distribution of compressive residual stress. The numerical model was established to simulate laser shock peening, to investigate deformation behavior and surface residual stress during laser shock peening. The results indicate that the axial stress wave and surface stress wave are induced by laser shock, which affect the deformation progress and the distribution of surface residual stress and plastic deformation. In the overlapping laser shock, the distribution of plastic deformation is uneven at the bottom of the overlapping dimple, with the appearance of the pile -up at the edge. Moreover, the non-homogeneity of the surface residual stress field is obvious in the dimple region. The above inhomogeneity is related to the propagating process of surface stress wave that is affected in the dimple region due to the boundary effect, but can be reduced by altering laser pulse duration.