Mechanical and corrosion performances of Al–Mg-Mn 5083 rolled alloys microalloyed with Sc and Zr in different thermomechanical processing conditions

The mechanical properties, corrosion behavior, and related microstructures of Al–Mg-Mn AA5083 rolled sheets microalloyed with Sc and Zr were investigated under various thermomechanical processing conditions. The results revealed that adding 0.05 wt.% Sc resulted in a minor change in the alloy performance relative to the base alloy. When the Sc content reached 0.1 wt.% it significantly improved the alloy strength and recrystallization resistance, and dramatically lowered the intergranular corrosion (IGC) susceptibility. Compared with the base alloy, the 0.1 wt.% Sc addition (along with 0.08 wt.% Zr) increased the yield strength (YS) by 8, 75, 25, and 33% for the cold-rolled (H18-), annealed (O-), extra-deformed (H116-), and stabilized (H321-tempers) conditions, respectively. In addition, the recovery and recrystallization resistances were significantly improved, as demonstrated by the retained deformed fibrous structure in the O- and H321-tempers. Furthermore, the IGC susceptibility was substantially decreased in the H321-temper due to the prevention of continuous β-Al₃Mg₂ precipitation along recrystallized grain boundaries. The YS of the final rolled sheets was modeled using constitutive analysis to predict the effects of various microstructural components on the strengthening contribution.