Effect of beam offset on microstructure and mechanical properties of electron beam welded Ti₂AlNb and TA15 alloys

During electron beam welding (EBW) of Ti₂AlNb/TA15, the fusion zone (FZ) was mainly composed of the softer B2 phase, which led to the softening of the joint. In this study, beam offset TA15 alloy was utilized to analyze its influence on the evolution of microstructure in FZ and joint performance. Results showed that the main component phase of FZ was transformed into martensitic phase by the beam offset process, the microhardness of the FZ was increased about by 110 HV and the softening problem was solved. When the beam offset distance reached 0.4 mm, the tensile strength of the joint at room-emperature was also increased by about 55 MPa, and the fracture position changed from FZ to heat-affected zone (HAZ) on Ti₂AlNb side. In addition, the plasticity of joint was slightly improved.