Intergranular corrosion susceptibility of 6061 aluminum alloy welded joints

The intergranular corrosion behavior of 6061 aluminum alloy welded joints produced by metal inert gas welding and friction stir welding was studied. The microstructure of the welded joints and the intergranular corrosion morphology of the cross-section were analyzed by optical microscopy. The results show that the most sensitive area of intergranular corrosion is the partially melted zone of the metal inert gas welding, and the maximum corrosion depth is about seven times that of the base metal, followed by the unmixed zone. The heat affected zone has the lowest sensitivity. Although the welding seam corroded seriously, general corrosion played a leading role. With the high heat input of metal inert gas welding, the sensitivity to intergranular corrosion in the partially melted zone increased significantly, while other zones had little change. For friction stir welding joints, the heat affected zone suffered from the most severe corrosion, and the nugget zone the least. However, the difference is not apparent. The susceptibility to intergranular corrosion of friction stir welding joints is weaker than that of metal inert gas welding joints but more severe than the base metal.