Methods for the suppression of “residual stress holes” in laser shock treatment

The “residual stress hole” destroys the uniformity of the residual stress distribution on the surface of laser shock-induced materials. Inhibiting the formation of the “residual stress hole” has significance for better exerting the surface modification effect of laser shock. This paper proposes the concept of the “energy blank zone”, which intends to place an area without laser energy distribution inside the laser beam to prevent the “boundary effect” from converging toward the center of the beam. The influence of the laser energy distribution on the formation of residual stress on the surface of laser shock-induced materials has also been investigated by utilizing finite element simulation. For the laser shock processing conditions selected in this paper, the central region of the beam had a relatively low energy distribution, which caused the laser shock processing effect to present an improvement trend. Based on the research results, some methods have been proposed to restrain the formation of the “residual stress hole”. The selection and optimization of the specifications of the “energy blank zone” and the specific mode of energy distribution need to be completed by multi-parameter comparative analysis. This paper provides technical references and solutions for the industrial application of laser shock surface strengthening technology.