Abstract:The thermal effects of TC4 titanium alloy during laser welding induce microstructural heterogeneity and residual stress in the weld joint, significantly compromising its corrosion resistance. This study investigated the influence of pulsed magnetic field treatment with varying intensities (0.5, 1, 1.5, and 2 T) on the corrosion behavior of welded joints. Results show that magnetic field treatment effectively enhances corrosion resistance, with optimal performance achieved at 1.5 T. Compared to untreated specimen, the 1.5 T-treated specimen exhibits remarkable improvements: polarization resistance (Rp) increases by 13 times, corrosion current density (Icorr) decreases by 30.3%, passivation current density (Ip) reduces by 40.5%, while mass loss rates after HCl immersion for 20 and 40 d decrease by 1.7% and 10.3%, respectively. The decrease in homogeneity index (D-value) of residual stress distribution show a trend of initial increase followed by decrease with ascending magnetic intensity. At 1.5 T, the D-value reduction in x-direction reaches 27.92%, corresponding to optimal energy matching between magnetostrictive effects and dislocation motion. Beyond 1.5 T, magnetostriction saturation induces lattice distortion and dislocation pile-ups, diminishing stress redistribution efficiency. Magnetic treatment facilitates dislocation migration and annihilation, reducing local strain (5.8%?6.9% decrease in KAMave) and residual tensile stress (72.0% reduction). This process alleviates stress concentration and decreases the proportion of low-angle grain boundary, effectively releasing type II internal stresses and decreasing corrosion susceptibility. This research proposes an innovative, cost-effective, and eco-friendly post-processing strategy for titanium alloy welded structures.