The mechanical properties and corrosion resistance of a sustainable aluminium–magnesium alloy with increasing iron impurity from secondary aluminium scraps

The microstructure, mechanical properties and corrosion resistance of a non-heat treatable structural aluminium alloy, AA5754, were investigated regarding different Fe contents. The alloy was assumed to be made with a high volume of post-consumer aluminium scraps, so the impurity Fe was increased from the regular level, ~0.25 wt.%, to an unusually high level, ~1 wt.%. The effects of increasing Fe on the microstructure, mechanical properties and corrosion resistance of the final sheet products were systematically studied. It was summarised that, with increasing Fe, strength increases slightly, formability decreases significantly, and resistance to pitting corrosion decreases, while most of the other properties, e.g. castability and rollability, are not much affected. Therefore, the AA5754 made with a large volume of post-consumer aluminium scraps could be fabricated without changing the casting and sheet‑processing route, but great caution should be taken in applications. Between ~0.25 and ~0.75 wt.% Fe, the alloy can be used in applications where moderate formability and corrosion resistance are required. Above ~0.75 wt.% Fe, it can only be used when no cold formability and little corrosion resistance are required.