<p>This study investigates the effects of pulsed magnetic field treatment (PMT) on the microstructure and mechanical properties of the weld zone in TC4 titanium alloy joints produced by argon arc welding. The analysis revealed that a high density of nano-scale acicular α′ martensite phase is formed in the weld. These needle-like structures were observed to be interwoven, forming a characteristic basket-weave morphology. The interfacial spacing is lowered down. The texture is weakened that enhance the isotropy performance. Furthermore, the study reveals that PMT not only facilitates the recrystallization process but also transforms high-angle grain boundaries (HAGBs) into low-angle grain boundaries (LAGBs), achieving approximately 4% grain refinement. In the weld zone, the dislocation density decreases and its distribution becomes more homogeneous together with more flexible motility and combed morphology. Optimal mechanical properties were observed at a magnetic induction intensity of 3&#xa0;T with 30 pulses, where the weld zone exhibited an elongation of 6.31% and a tensile strength of 894.46&#xa0;MPa, representing improvements of 41.12% and 1.99%, respectively, compared to the untreated state. The synchronous improvement of strength and plasticity are realized. The magnetic field prompts the electron excitation and improves the dynamics conditions.</p> Graphical abstract <p></p>