Evolution of microstructure and mechanical properties of vacuum electron beam welded joints in a near beta titanium alloy: Influence of heat treatment

Herein, the two plates of a near beta titanium alloy (Ti55531) with a thickness of 60 mm were welded by vacuum electron beam welding, and full penetration welded joints were obtained. The results show that the welded joint can be divided into weld bond, heat affected zone and base metal. Microstructures of weld bond and heat affected zone are composed of coarse beta grains and fine a phases distributed at the beta grain boundaries and in the beta grains, and the beta grains in weld bond are coarser than those in heat affected zone. The solution treatment can reduce the microhardness and improve the impact toughness of different zones of the joint. The tensile strength of the welded joint can be improve to 1129 MPa by solution and aging treatment. The influence of heat treatment on microstructures and mechanical properties of these welded joints were discussed in detailed.