Effect of compensating aluminium alloy during friction stir welding of Al-Cu alloys having dissimilar thicknesses

Producing a stable weld without offsets using friction stir welding is quite challenging. Apart from the offset issue, cross-sectional adjustability is a must-have feature for the Al-Cu joint because of the differences in electrical conductivity. In this paper, two different approaches, Horizontal and side tilt angle condition, were implemented by shifting the Cu, 1 mm below the Al level, which provide an additional volume of Al in the weld zone, and results were compared with the welds produced without offset and compensating Al alloy. Rotational speed of 640 rpm and welding speed of 160 mm/min was used for all the experiments. Horizontal bed approach result in 74% improvement whereas side tilt angle condition results in 48% enhancement in tensile strength. However, joint efficiency attained with the horizontal bed condition (91%) is higher due to better material mixing and fewer defects as compared to the side tilt angle condition (77%). On the other hand, the side tilt angle approach generates a flash-free joint and exhibits the potential to build long welds.