Optimization of residual stress field and improvement of fatigue properties of thin-walled pipes by filling laser shock peening

In present work, a kind of filling laser shock peening (LSP) method is put forward and applied to thin-walled pipe. Specimens are experimentally and numerically investigated to identify the residual stress field and fatigue properties of pipe with and without LSP treatment. Numerical simulation indicates that the residual compressive stress increases first and subsequently drops as the laser power density increased, and the extent of influence of the stretching wave reflected from the lower surface on the unloaded area increases with the spot diameter causing surface tensile stress in the unloaded area. By filling the guided wave material within the pipe, the residual stress field of the pipe treated by LSP is optimized, and the influence of the stress wave reflection on the residual stress field is effectively decreased. The surface residual stress of the filled guided wave material is -326MPa, improving by 57.6% as compared with unfilled guided wave materials pipe. The fatigue life of the pipe with filled waveguide material treated by LSP is extended by 48.9% as compared with untreated pipe.