Effect of aging treatment on tensile properties and intergranular corrosion of spray-formed 7055 Al alloy

Purpose This paper aims to study the effect of aging treatment on tensile properties and intergranular corrosion (IGC) of spray-formed 7055 Al alloy. Design/methodology/approach This study involved tensile test and IGC test, along with scanning electron microscopy, transmission electron microscopy and X-ray energy dispersive spectroscopy analysis. Findings The findings suggest that the quantitative characteristics (type, size and volume fraction) endow the alloys with different tensile properties and fracture morphologies under different aging treatments. The higher corrosion susceptibility of the under-aged alloy is mainly attributed to the continuous distribution of grain boundary (GB) precipitates, which provide corrosion channels for anodic dissolution. For the DA and retrogression and re-aging alloys, the size, interspacing and Cu content of grain boundary precipitates (GBPs) increase as the aging degree deepens, which is favorable for GB to resist anodic dissolution. Furthermore, the PA alloy has the highest corrosion susceptibility due to the combined influence of the low Cu content in GBPs, the continuous distribution of GBPs and the narrow precipitate-free zone. Originality/value The continuity of GBPs has a limited impact on the corrosion mode. By comparison, the effect of the corrosion potential difference on IGC is much greater than that of the continuity of GBPs.