Evaluation of Microstructures and Mechanical Properties of Dissimilar Materials by Friction Welding

Abstract

The joining dissimilar metals demanding increasing importance in many industrial applications to utilize hybrid structures and reduce the cost and weight of components. The applications of dissimilar metal aluminium – copper alloys are widely involved in defence, aviation, power transmission and automobile industries due to its combinations of properties such as high strength to weight ratio, excellent mechanical properties, high resistance to corrosion and low density. However, the joining of aluminium to copper by conventional fusion welding techniques are not feasible to weld because of the newly formation of brittle intermetallic compounds at the weld pool. Hence, to overcome these problems new welding processes with high reliability and productivity for these combinations of dissimilar materials are demanded. The present work therefore studied the continuous drive friction welding of aluminium to copper for defence applications. As a result, the tensile strength of the joints achieved was 3.8% higher than base material of the aluminium. The microstructural characterization of the weld interface was analysed by optical and scanning electron microscopy and X-ray diffraction analysis technique. Microhardness profile across the welds was showing the maximum hardness value obtained at weld interface. The joints were examined with X-ray diffraction technique in order to understand the formation of secondary phases at weld interface during welding. Tensile fracture of the welded joint occurred at aluminium side and the fracture morphology characterizing by ductile mode of failure with dimple structure.