Enhancing corrosion resistance of the nugget in a 2519-T87 aluminum alloy friction stir welded joint via tungsten inert gas arc

Abstract

The corrosion resistance of the nugget zone (NZ) in two 2519-T87 aluminum alloy joints obtained by conventional friction stir welding (FSW) and tungsten inert gas arc-assisted FSW (TIG-FSW) was evaluated by immersion corrosion tests and electrochemical measurements. The results show that TIG arc significantly enhances the corrosion resistance of the nugget, the maximum corrosion depth is reduced by about 59.6%, and the polarization resistance is increased by about 14.5%. The mechanism was discussed based on microstructural examination. TIG-FSW decreases the area fraction of coarse intermetallic compounds (IMCs) with an equivalent diameter larger than 2.0 μm and increases the number of submicron IMCs, avoids the accumulation of IMCs, leads to low local electrochemical activity, and consequently enhances the corrosion resistance of the NZ.