Effect of Heat Input on Microstructure and Mechanical Properties of Laser Self Fluxing Brazed Ti/Al Dissimilar Alloy Joints

The TC4 titanium alloy and 6061 aluminum alloy were butt welded by using IPG 6000 fiber laser.The laser self fluxing brazed joint was obtained with the laser beam shifting to the aluminum side.The effect of heat input on the microstructure and mechanical properties of TC4/ 6061 titanium aluminum dissimilar joint was analyzed by metallographic microscope, scanning electron microscope and tensile test.The results show that when the heat input exceeds 133 J/mm, more brittle intermetallic compounds are formed at the interface, and the main intermetallic compounds are TiAl₃ and TiAl₂.When the heat input is less than 133J/mm, the intermetallic layer is very thin, about 1 μm, and the main intermetallic compound is TiAl₃.When the heat input is 107J/mm, the maximum tensile strength of TC4/6061 dissimilar joint is 212 MPa, which is about 63%of that of 6061 aluminum alloy.The fracture mode of TC4/6061 dissimilar joint is ductile brittle mixed fracture.