Corrosion Evolution Behavior of 7075 Aluminum Alloy FSW Welded Joints in Seawater

The entire corrosion mechanism of various regions and their parent materials of 7075 aluminum alloy FSW welded joints in simulated seawater was studied by observing the morphology, analyzing polarization curves, and conducting accelerated corrosion tests. The result showed that the different microstructures and second phases of various areas of the welded joints and their parent materials were the main reasons for their different corrosion morphology characteristics and corrosion resistance. With the prolongation of corrosion time, the corrosion damage in each area of the welded joint evolved in the order of pitting corrosion, intergranular corrosion, and exfoliation corrosion, and proceeded in a cyclic manner. The seawater corrosion damage degree of each area of the welded joint was higher than that of the base metal, and heat-affected zone (HAZ) had the worst corrosion damage during the corrosion process, which was the area with the worst corrosion resistance of the welded joint.