Influence of Process Parameters on Aluminium Alloy 6061-O Joints by Friction Stir Welding Process

The present work reports the influence of process parameters (tool speed, traverse speed and axial load) on the metallurgical and mechanical properties of joints fabricated by friction stir welding process. The samples were friction stir welded under tool rotational speed of 1120, 1250 & 1500 rpm and traversing speed of 0.5, 0.6 & 0.8 mm/sec with an axial load of 9000 Kg constant for all the trials. Single pass friction stir welding process was followed in this investigation. Metallographic analysis was carried out across various zones of weldments (Unaffected Base Metal, Heat Affected Zone, Thermo Mechanically Affected Zone and Nugget Zone). Mechanical tests (microhardness survey & tensile test) were evaluated and all the results were correlated with the parent base metal. For better understanding scanning electron microscope (SEM) analysis was carried out in the nugget zone to predict the flow of materials due to severe stirring process. It is observed from the results that joint fabricated with a tool speed of 1250 rpm, traverse speed of 0.8 mm/sec and axial load of 9000 Kg showed a defect free joint, with better refined grain structures and high tensile strength when compared to all other trials done.