Effect of End Profile on Dissimilar Metal Friction Welds of Pure Aluminium and Pure Copper

Some of the applications in the fields of automobile, power transmission, aerospace etc. require materials with good corrosion resistance, high electrical conductivity, machinability and weldability. In such cases, aluminium (Al) and copper (Cu) are candidate materials. In most of the cases, the applications demand sound dissimilar metal welds of Al and Cu. Joining of dissimilar metals is always a challenging process because of notable difference in the chemical properties, mechanical properties and thermal properties of the materials and also the formation of intermetallic compounds which are brittle and hard at the boundary between base metals. Joining Al and Cu employing conventional fusion welding process is difficult due to metallurgical incompatibility, difference in melting point, thermal mismatch etc. Inter-metallic compound phases formed during welding at the weld interface are brittle in nature and greatly affect the mechanical properties of Al-Cu joints. In order to overcome this problem, these metals are welded using solid-state welding process viz. friction welding. It is observed that significant joint strength is not obtained as Al is only deforming and there is no deformation of Cu during friction welding. In order to achieve good joint strength an attempt is made by varying the end profile of the Cu and welded to Al by friction welding. Different profiles on Cu rod, such as conical, conical with threads and face knurled were taken and welded to plane Al rod. It is observed that the change in profile did not show significant improvement in the joint properties.