Influence of Interface Morphology on the Bond Strength During the Reshaping Process of Al-Cu Bimetal Pipes

With the increasing advances in various industries such as aerospace, chemical and fluid transfer, manufacturing of bimetal noncircular tubes as their frequent use is more than ever important. In the present study, the squaring process of aluminum-copper bimetal pipes produced by explosive welding, using rolling process was studied. The effect of interface morphology on the microstructure and strength of the bond interface during the reshaping process was investigated by an optical microscope and shear strength test. Moreover, the presence and distribution of the intermetallic compounds at the interface was investigated by the electron microscope and energy dispersive X-ray spectroscopy analysis. The results show that the wavy form of the interface and the continuity and thickness of the intermetallic compound layer which is formed at the interface of the initial round pipes have a major importance during the reshaping process and effect on the mechanical properties and interface quality of the finished square tubes. Bond strength of tubes with wavy form interface and minimal intermetallic compounds at their interface, have not changed significantly before and after the forming process but the bond strength decreases by increasing the thickness of intermetallic compound layer and the drop in bond strength during the forming process is more severe for the tubes with thicker intermetallic compounds layer at their interface.