Microstructure and Mechanical Properties of Laser Welded Ti/Al Alloys

The welding of TC4 Ti alloy and 6082 Al alloy is realized by 3 kW fiber laser offset welding on Al sheets. The macro- and micro-structures and mechanical properties of joints arc tested. The temperature field distribution of joints and the thermal cycling curves at Ti/Al interfaces arc simulated by the finite element method. The results show that the joints without cracks and porosity and with good tensile strength can be obtained by Ti/Al laser offset welding. During the welding process, the Ti substrate is partially melted and its surface becomes uneven. In the solidification process, there occurs a thin intermetallic compound layer at the Ti/Al bonding interface, whose main phase is TiAl3. The tensile test show that the maximum tensile strength of joints is 153 MPa, 72.9% that of Al substrate. The fracture mode of joints is a brittle cleavage one. The fractures occur in the intermetallic compound layer, and brittle phases which cause the fracture arc TiAl and TiAl3.