Microstructure evolution behavior of titanium alloy during the electromagnetic pulse welding process between titanium and stainless steel

Electromagnetic pulse welding (EMPW), shows promising prospects in the connection of titanium alloy and stainless steel. However, the influence of the EMPW process on the microstructure of titanium alloys remains insufficiently understood. EMPW experiments were conducted on TA1 titanium alloy and 304 stainless steel plates using discharge energies of 4.5 kJ, 7 kJ, 10 kJ, and 13.7 kJ. The microstructure of the bonding interface was characterized and analyzed by scanning electron microscope (SEM) and electron backscatter diffraction(EBSD) to examine features such as morphology, dislocation evolution, and twin distribution. The findings indicate that titanium alloy experiences significant plastic deformation at elevated strain rates during EMPW, leading to continuous accumulation of dislocation slip and activation of the twinning mechanism. The synergistic effect of these two mechanisms enhances plastic deformation and grain refinement in the titanium alloy. As the discharge energy rises, the dislocation density in the weld zone gradually increases, and the peak value of local orientation difference rises from 3.71 to 4.87. The twinning mechanism intensifies gradually, which does influence the local grain orientation of titanium alloy to some degree. The bonding interface presents two typical morphologies: wave interface and flat interface. The microscopic evolution behavior of these two morphologies differs somewhat based on the direction of force. This work could provide references for understanding the evolution mechanism of metal microstructure during EMPW process. • Use aluminum driver plates as the medium for energy transmission. • The reliable welding joint of Ti/SS was obtained by using EMPW. • The titanium alloy grains in the welding area have been refined. • Dislocation slip and twinning dominate plastic deformation.