Research on TC4 Titanium Alloy Sheet Welded by Pulsed Electron Beam Welding

The welding experiment of 1.2 mm TC4 titanium alloy sheets was carried out by conventional continuous electron beam welding and pulsed electron beam welding with different frequencies. Then, the microstructure and mechanical properties of the welded joint were tested. Results show that pulsed electron beam welding can form welds without fusion defects. As the frequency increases, the weld undercut and backside weld reinforcement decrease and the surface formation is improved. Due to the change of welding thermal cycle, the pulsed beam flow can accelerate the cooling rate of the molten pool and refine the microstructure grains. Both DC and pulsed electron beam welded joints are broken in the base metal zone during tensile process, so the tensile strength is higher than that of the base metal. The high -frequency pulsed electron beam can improve the plasticity of the welded joint and the micro-hardness of the weld zone and heat-affected zone. When the frequency is 10 kHz, the elongation after fracture of the welded joint can reach 14.9%, which is about 80% of that of the base metal, and the microhardness (HV0.2) of the welding and heat affected zone are 3750 and 3680 MPa, respectively.