Effect of welding speed on microstructures and mechanical properties of Al/Cu bimetal composite tubes by a novel friction-based welding process

In this work, a novel friction-based welding technology was developed to weld Al/Cu bimetallic tubes. The macrostructure, microstructure evolutions, and mechanical properties of the joint under different welding speeds were investigated. Void defects are observed on the joint interface, especially at the welding speed 60 mm/min. From the Al side to the Cu side, the reaction layer can be divided into five layers. In addition, welding speed has an important influence on the microstructure evolution of reaction layer. Compression-shear testing results show that the shear strength decreases with the increase of the welding speed. The failure of compression-shear samples is first generated at the junction of hypereutectic layer and intermetallic compound (IMC) layer, and then, the crack propagates along the interface of the hypereutectic layer and IMC layer or through the hypereutectic layer to the eutectic layer.