Microstructure evolution and mechanical properties of linear friction welded Ti₂AlNb alloy

Abstract A Ti₂AlNb-based alloy was welded by linear friction welding (LFW). The microstructure and mechanical properties of the LFWed joint were investigated. The results indicate that a defect-free joint can be obtained using LFW. The weld zone of the welded joint is composed of B2 phase and a few residual O and α₂ phases, and it features primarily low angle grain boundaries. In thermo-mechanically affected zone, most O phase has gradually turned into B2 phase and the α₂ phase has changed into a small spherical microstructure. With increasing the distance from the weld zone to the base metal, more coarse and needle-shaped O phase could be found while α₂ phase almost remain unchanged. The microhardness presents a total decrease by about 80HV from the base metal to the weld interface. The average tensile strength of the joint at room temperature is 1136 MPa, which is basically comparable to that of the base metal. And the tensile elongation of the joint achieves 76% of the base metal.