Factors affecting the strength and formability of alloys based on Al–3 wt.% Mg

Aluminium alloys in sheet form based on Al–3 wt.% Mg (e.g. AA5754 and AA5454) have found application in automotive structures as they offer attractive combinations of strength, formability, corrosion resistance and weldability. In this paper, some results from studies aimed at understanding the effects of both alloy composition and sheet processing on the strength and formability, in particular, of alloys based on Al–3 wt.% Mg, are described. Specifically, the effects of Mn additions and grain size on strength and formability have been studied. It is shown that the effect of Mn on yield stress can be understood in terms of the expected contributions from both solid solution strengthening and any grain size strengthening. In addition, the level of Mn is shown to affect the general formability of the alloy through its influence on the volume fraction of the coarse constituent particles.