Investigation on surface “residual stress hole” of thin plate subjected to two sided laser shock processing

Abstract

Two sided laser shock processing (TSLSP) is a novel surface processing technology, which is often used in surface modification of thin-section parts. In this paper, the phenomenon of residual stress hole (RSH) on the surface of 304 stainless steel thin plate subjected to TSLSP was researched by numerical simulation and experiment method. The influence of boundary reflection on surface residual stress field was investigated in detail. Based on the developed model validated by experiment, the effect of some key parameters such as spot diameter, spatial pressure distribution, peak pressure on RSH were further studied. The investigations show that the RSH does not occur when the very thin plate subjected to TSLSP. The RSH phenomenon mainly results from the convergence of surface stress wave emitted from the boundary of laser spot. When the size of treated plate is small, the effect of surface stress wave reflected by the plate boundary on the RSH cannot be neglected. Under the same conditions of TSLSP, the RSH easily occurs on the surface of the related thick-sectional sample. The peak value of RSH does not significantly vary with the increase of spot diameter, but the width of RSH broadens. The spatial pressures distribution of shock wave affects the RSH phenomenon. With the enhance of the applied pressure of shock wave, the RSH phenomenon becomes more obvious.