Mechanical performances and corrosion behaviors of friction stir welded and TIG welded 2219 aluminum alloy joints

Mechanical performances of friction stir welding (FSW) and tungsten inert gas (TIG) welded 2219-CS aluminum alloy joints were evaluated. The macro and micro zone corrosion behaviors were characterized by intergranular corrosion, exfoliation corrosion, and electrochemical corrosion. The morphologies of corroded surfaces were analyzed with the help of optical microscopy and scanning electron microscopy. The results showed that the fine-grain microstructures and homogeneous redispersed precipitates in the weld nugget zone of friction stir welded joints greatly improved their corrosion resistance. The anti-corrosion performances of the heat affected zone of friction stir welded joints were also better than those of the fusion welded joints, which were attributed to the less re-dissolving and coarsening of the precipitates. The higher electrochemical homogeneity of the friction stir welded joints contributed to the significantly reduction in corrosion rate.