FRICTION STIR WELDING OF ALUMINIUM-COPPER ALLOYS

Abstract

Friction stir welding (FSW) is a relatively new solid state thermo- mechanical welding process for joining ferrous and non- ferrous similar or dissimilar materials and plastics, where the weld is produced by softening, plastic deformation combined with forging action caused by tool rotation of base metal. This process is used widely because it produces sound welds which does not have common defects such as solidification and liquefaction cracking that occur in fusion welding. In recent years, a lot of research work has been reported on Friction stir welding (FSW) of dissimilar systems such as Aluminium to copper and Aluminium to Brass. FSW of Aluminum to brass has captured the essential attention from manufacturing industries such as railway, shipbuilding, automotive and aircraft production. Aluminium and brass materials are widely used in the industrial applications because of their excellent electrical and thermal conductivities, high strength, high corrosion and fatigue resistances. The joining of copper to aluminium alloys can be used for making a aluminium bimetallic parts in a wide range of industrial areas. In Friction stir welding (FSW),there are only three process parameters such as tool rotational speed (rpm),travel speed and pressure force which can be easily controlled, process variables tool rotational speed (rpm) and travel speed (mm/min) are used in this study keeping the pressure force constant. The overall aim of this study is to get the optimum welding parameters for Friction stir welding ( FSW) of aluminium and brass plates of 5 mm thickness, investigation of the weld strength , micro hardness across the weld , Heat Affected zone (HAZ) ,Thermo- Mechanical Affected Zone (TMAZ) ,grain size of the weld, microstructural study and fractography of the fracture surfaces. In this research study Ultimate tensile testing machine and Vickers micro-hardness testing machine for the evaluation of mechanical properties of Aluminium to Copper alloys welded joint at different rotational and travel speeds , Optical microscope (OM) and Scanning Electron Microscopy (SEM) to investigate the microstructural properties and metallographic studies are used. First a review is made on the current state of art research on friction stir welding (FSW) of aluminium and copper alloys keeping focus on the analogy of weld microstructure and mechanical properties testing and suitable parameters are systematically identified to produce sound welds on the selected dissimilar Aluminum-Copper alloys system to gain an insight of the various welding parameters and finally further research in this field of study has been suggested