Nine welding technologies were employed to weld sheets of TC4 titanium alloy of 2 mm thick.The properties of the joint were studied by analyzing and comparing the microstructure of weld and HAZ,mechanical properties of the joint and fractographs of tensile specimen.The obtained results show that the appearance of weld,effect of the protection and the mechanical properties of the joint are all in good condition when the welding parameters are as follows: welding current = 80 A;welding speed =15 m/h;and argon...