Research on the Microstructure Evolution of TC4 Titanium Alloy Joint Fabricated by Continuous Drive Friction Welding

In this paper, TC4 titanium alloy pipes were achieved by continuous drive friction welding, metallographic microscope and microhardness tester were used to evaluate the microstructure and the hardness of the joints, and the effect of friction pressure on the microstructure was studied. Under the selected welding parameters, all the joints have good morphology. The martensite is formed at the weld zone and the flash, which leads to a higher hardness on the weld zone. With the increase of friction pressure, the width of the weld zone, the grain size and LAGB (low angle grain boundary) at the weld zone decreases. In addition, dynamic recrystallization increases first, but when the friction pressure reaches 65 MPa, the deformation dominates.