Effects of heat treatments on the microstructure and localized corrosion behaviors of AA7075 aluminum alloy

Five different heat treatments were applied to AA7075 aluminum alloy, resulting in distinct localized corrosion behaviors in 5 wt% NaCl solution. Some treatments exhibited higher intergranular corrosion (IGC) susceptibility due to the anodic nature of grain boundaries (GBs) caused by Cu depletion in the precipitate free zones (PFZs) along the GBs. Cu-enrichment and an increase in intervals between η-phase grain boundary precipitates (GBPs) did not improve IGC resistance. The open circuit (OCP) and galvanostatic (GL) tests could distinguish differences in corrosion behaviors, suggesting the potential use of GL testing as a faster method for predicting localized corrosion behaviors.