Fundamental research on fatigue-resistant and low-stress welding repair technology through arc composite laser shock forging

In order to reduce residual stresses during the repair process of fatigue damage, enhance repair quality, and improve fatigue life, this study introduces a novel in-situ repair technology called arc composite laser shock forging technology (Weld-LSF). The paper establishes a transient thermo-mechanical coupled model for Weld-LSF based on the finite element method. It analyzes the thermomechanical behavior of a circular tube during the Weld-LSF process. The research findings demonstrate that Weld-LSF technology can effectively improve the residual stress field in the repaired layer, with the peak tensile residual stress in the weld seam decreasing from 510 MPa to 417 MPa following Weld-LSF treatment. Furthermore, fatigue tensile tests on welded components produced by different repair methods demonstrate that the average fatigue cycle number for arc-welded (AW) components is 129,033 cycles, whereas for components treated with Weld-LSF, the average fatigue cycle number is 250,233 cycles, indicating a 93.9 % increase in fatigue life. This study delves into the impact of Weld-LSF technology on residual stress and fatigue life of the repaired layer, thereby providing a theoretical foundation for the application of Weld-LSF technology.