Study of the welding conditions during similar and dissimilar aluminium and copper welding based on torque sensitivity analysis

The aim of present study was to analyse and compare the influence of the welding conditions on torque evolution, during similar and dissimilar friction stir butt welding of 5083-H111 aluminium alloy and copper-DHP. The torque registered during welding, using different welding parameters and base materials combinations, and its relation with the morphological and structural properties of the welds were analysed. Independently of the materials to be welded and the relative plates positioning, in dissimilar friction stir welding, the sensitivity of the average torque to the process parameters was observed to be the same. It was also observed that the average torque is strongly conditioned by the materials to be welded, since, for all welding parameters, the lowest average torque values were always registered during dissimilar welding. Material flow and intermetallic-formation were found to determine this behaviour. Important differences in instantaneous torque evolution, during welding, were also observed depending on base materials combinations.

► Welding torque is conditioned by the materials to be welded.
► Intermetallics formation promotes tool slippage in aluminium/copper welding.
► Tool slippage leads to the decrease of the average welding torque.
► Intermetallics formation promotes fluctuations in instantaneous welding torque.