Joining Characteristics of Ti/Cu Joint Welded by Resistance Spot Welding

To tackle the development of large-capacity titanium shell batteries, resistance spot welding was performed to join 1 mm thick TA2 titanium plate and T2 copper plate with a tungsten electrode on the copper side and a CuCrZr alloy electrode on the titanium side. The microstructure of the interfacial zone of the joint was systematically observed and analyzed, and the tensile shear bearing capacity of the joint was evaluated. At the interface zone in the peripheral region of the weld, a CuTi layer was formed adjacent to the titanium side, and a Cu₄Ti layer was formed adjacent to the copper side; at the interface zone in the central region of the weld, four layers-CuTi₂, CuTi, Cu₄Ti₃, and Cu₄Ti-were formed. The tensile shear load of the joint exhibits a trend of initially increasing and subsequently decreasing as the welding current increases or the welding time extends, and the tensile shear load of the joint reaches the maximum value of 5.50 kN when the welding current is 18 kA and the welding time is 400 ms. The research findings suggest that despite the feasibility of resistance spot welding between titanium and copper by utilizing tungsten electrodes on the copper side, the intermetallic compound layer formed at the welding interface serves as the crucial factor influencing the performance of the joint.