Microstructure and Mechanical Properties in Dissimilar Butt Friction Stir Welding of Severely Plastic Deformed Aluminum AA 1050 and Commercially Pure Copper Sheets

In this study, AA 1050 aluminum alloy and commercially pure copper in annealed and severely plastic deformed conditions were used. The technique used for imposing the severe strain to the sheets was constrained groove pressing (CGP) process. The annealed and severely plastic deformed sheets were subjected to friction stir welding (FSW) at different rotation and traverse speeds. Cu was placed in advancing side. Constant offset of approximately 1 mm was used toward Al side for all welds. A range of welding parameters which can lead to acceptable welds with appropriate mechanical properties was found. For the FSWed CGPed samples, it was observed that the welding heat input caused grain growth and decrease in hardness value at Al side of the stir zone. It was found that, generally the weakest parts of weld joints of annealed and CGPed samples were Al base metal and stir zone, respectively. Further investigations showed that several forms of intermetallic compounds were produced.