Study on mechanical, micro-, and macrostructural characteristics of dissimilar friction stir welding of AA6061-T6 and AA7075-T6

This research presents the effect of welding speed on dissimilar joints of AA7075-T6 and AA6061-T6 alloys. The weld quality was evaluated through observations of the macrostructure. The mechanical properties of the welds, including the ultimate strength, the percentage of elongation, and the microhardness variations, were determined for different welding speeds. Also the effect of the positions of the two alloys on the mechanical properties was investigated. In addition, during the friction stir welding (FSW) process, the peak temperatures were measured in order to indicate the relation between the peak temperature and the hardness distribution at the heat-affected zone (HAZ). Accordingly, the influence of the welding speed on the developed grain size was elucidated by the micro structural analysis.