The intergranular corrosion susceptibility of 2024 Al alloy during re-ageing after solution treating and cold-rolling

The intergranular corrosion (IGC) susceptibility of 2024 Al alloy during re-ageing after solution treating and cold-rolling was investigated by accelerated corrosion testing, open circuit potential testing, transmission electron microscopy and scanning electron microscopy. The absence of IGC in both the peak-re-aged and over-re-aged samples is related to the dislocation pile-ups which prevent the supersaturated solutes from diffusing into the grain boundaries and precipitating the continuous S-Al2CuMg phase. The aggregated pitting corrosion in the over-re-aged samples arises from the S-phase precipitates on the dislocation cell walls which accelerate the anodic dissolution of the cell interiors.