Experimental Investigations on AA 6061 Alloy Welded Joints by Friction Stir Welding

Aluminum and aluminum composites play important role in aerospace, automo-bile, marine and structural applications. Literature shows that some of the con-ventional fusion welding processes in joining of aluminum metals result in defects like porosity, distortion owing to elevated thermal conductivity and solidification shrinkage. To overcome such issues, experimental investigations are conducted using Friction Stir Welding (FSW) process in joining of metal plates of aluminum 6061 alloy. Weld joint samples are cut to required sizes and secured them in position by mechanical clamps. The setup is loaded onto Vertical Machining Centre. Nonconsumable tool tips of four different shapes of tungsten carbide and H13 materials are prepared and attached to the spindle. The machine is started and allowed spindle to rotate the tool to plunge onto metal plates along joint line. An axial force is continuously applied until sufficient heat is generated at mating surfaces for joining. Experiments are repeated at different levels by varying welding parameters. Joints are tested for their mechanical properties. The microstructural analysis is studied by SEM. Artificial Neural Network (ANN) simulation model is developed for validation. ANOVA is applied for validation of output results of mechanical properties and optimal process parameters are determined. Research shows that joints are influenced by profile of tool pin and, therefore, the rotational speed of the tool.