Improvement of Impact Energy for Copper/Aluminium Friction Welded Joint due to the Shape of Interface Edge

摘要

The friction welding for copper and aluminium is useful to minimize the diffusion thickness at the interface between copper and aluminium. The minimization of diffusion thickness is required for maintaining the joint strength, because brittle intermetallic compounds are formed at the friction weld interface between copper and aluminium. However, the improvement techniques on joint strength characteristics have not fully been clarified. In this study, stress singularities at the intersection of free surfaces and the interface between copper and aluminium are investigated using finite element analysis. It was confirmed that the no free-edge stress singularities existed in case of convex angle. In this experiment, copper and aluminium friction welded joints with convex apex angle were fabricated as to minimize the diffusion thickness, such as > 1 μm at the interface between copper and aluminium. It was confirmed that the good tensile strength could be observed in any cases. The Charpy impact energy became comparatively low values in case of 90 degree of apex angle, and revealed a remarkable good impact energy can be obtained in case of the convex angle that showed no free-edge stress singularities.