Weld temperature effects during friction stir welding of dissimilar aluminum alloys 6061-t6 and 7075-t6

The objective of this work is to establish nominal friction stir [butt] welding process parameters for joining 4.76-mm-thick aluminum alloys 6061-T6 and 7075-T6 and to improve the joint quality via programmed tool offsets. In addition, dynamic tool–workpiece interface temperatures are measured during welding and used to explain the effects of alloy placement and weld tool offset from the joint. Weld tool offsets into the retreating side AA7075 increase the measured tensile strength of the dissimilar joint. The increased joint strength is facilitated by lower average weld temperatures with increasing amount of AA7075 stirred into the nugget.