Will the laser shock-induced residual stress hole inevitably occur?

The appearance of the residual stress hole (RSH) phenomenon makes the otherwise perfect laser shock processing (LSP) method potentially defective. Residual compressive stress distribution appears in the areas irradiated by the laser beam while the central position of the laser beam pursues the residual tensile stress individually. This is prominently seen in the numerical simulation of LSP experiments. However, the authors find that the existence of RSHs is ill-defined in most published testing results. A hypothesis that the cavitation effect inhibits the formation of RSHs based on the application of water in the laser shock process can be proposed.