TC4 titanium alloy fabricated by the electron beam additive manufacturing were welded by electron beam welding

and the microstructure and mechanical properties of the joints were analyzed. The results reveal that the microstructure of the base metal zone is composed of basket-wave shaped α+β phase

and the heat affected zone is composed of β-transformed structure and α′martensite. With closer to the weld joint

the martensite content is increased. A large number of elongated α′martensite exists in the weld zone

and the martensite is finer from the top to the bottom of the weld. The hardness of the base metal zone is the lowest

while the weld zone is the highest

and that of the heat-affected zone is increased significantly with the decrease of the distance from the center line of the weld. Joints are broken on the side of the base material

where the ultimate tensile strength and the elongation of the joint is 875 MPa and 7%

respectively

and the fracture type is characterized by ductile fracture.