Residual stress field induced by laser peening: A finite element analysis

A non-linear elastic-plastic finite element method to predict the residual stress distribution induced by Laser Shock Processing (LSP) in the AISI 304 stainless steel was established. This two dimensional FEA model considered the dynamic material properties at high strain rates (10⁶s^-1) and the precise determination of loading conditions. Effects of laser power density, laser spot size, laser pulse duration, multiple LSP processes and one/two-sided LSP on the compressive stress field in the stainless steel were evaluated for the purpose of optimizing the process. Numerical results have a good agreement with the measurement values by X-ray diffraction method and also show that the magnitude of compressive stress induced by laser shock processing is more than the welding residual stress. Therefore, laser shock processing is an effective method for protecting weldments against stress corrosion crack.