Corrosion susceptibility and mechanical properties of friction-stir-welded AA2024-T3 joints

The joining of AA2024-T3 with friction stir welding (FSW) at a rotational speed of 600 rpm and welding speed of 200 mm/min produces areas with significantly different heterogeneous microstructures, which relate to mechanical properties and corrosion behavior. In this study, the mechanical properties and corrosion susceptibility of different zones of an AA2024-T3 joint were investigated with tensile, hardness, and electrochemical testing. The joint was found to have reduced mechanical properties compared to base metal due to the significant microstructural changes. The developing localized high temperatures allow re-formation of the Guinier–Preston-Bagaryatsky (GPB) zone and dissolution of S phase, resulting in lowers hardness in the stir zone (SZ). Tensile test specimens failed in the lowest hardness area located in the heat-affected zone (HAZ) at the retreating side (RS). The SZ exhibited a relatively low pitting corrosion resistance compared to that of the BM and HAZ of the top surface, due to the refined grains and a larger number of intermetallic particles during welding.