The development of electron beam welding technology is advancing toward higher voltages

greater power

extended lifespan

improved stability

and intelligent control

positioning it as an ideal welding technique for thick titanium alloy structures. In this study

a high-voltage electron beam was employed to weld 20 mm thick TA15 titanium alloy

systematically analyzing the effects of 100 kV

120 kV

and 150 kV accelerating voltages on the microstructure and mechanical properties of the weld joints under consistent heat input. Additionally

the thermal action mechanisms of accelerating voltages on the welding process were also investigated. The results show that accelerating voltage significantly impacts local undercooling within the weld joint

and as the accelerating voltage increases

the undercooling degree decreases

thereby promoting the diffusion and transformation of alloying elements in TA15 titanium alloy

resulting in the formation of fine needle-like α′ phase and a small amount of lamellar α phase. At 150 kV

the room-temperature ductility of the TA15 titanium alloy was notably improved due to the increased presence of the β-phase and high-angle grain boundaries in the weld

which in turn enhances the alloy’s plastic deformation capacity. These findings offer crucial theoretical insights for the engineering application of high-voltage

high-power electron beam welding in the fabrication of thick and tough titanium alloys.