Microstructure and Properties of Dissimilar Butt Joints of Aluminum to Copper by Cold Metal Transfer with Preheating
摘要
The dissimilar butt joining of aluminum alloy and copper was successfully realized by cold metal transfer (CMT) welding–brazing with the help of preheating on copper. Preheating could balance the effect of the high thermal conductivity of copper on weld formation, and eliminate welding defects such as porosity, unfused zone, and cracks at the interface. Three layers of intermetallic compounds were observed at the brazing interface, namely, Al4Cu9, Al2Cu3, and Al2Cu. When the heat input was reduced to 648 J/mm, the total thickness of the interfacial IMC layers was suppressed to 4.83 μm, and the mechanical property of the joint was up to 91.35 MPa. The corrosion resistance of the Al/Cu welded joint was worse than that of the base metals, and corrosion occurred at the interfacial IMCs and the grain boundaries of the weld microstructure.