Effect of homogenization on the structure, hardness and corrosion resistance of 1570C alloy

Influence of homogenizing annealing on the parameters of grain structure, phase constituents involving nanoscale aluminides of transition metals, hardness and corrosion resistance of the aluminum alloy 1570C (Al-5Mg-0.18Mn-0.2Sc-0.08Zr, mass.%) ingot was studied to optimize its heat treatment regimes according to a two-stage annealing scheme. At the first step, the ingot was annealed at 360°С for 6 hours (conventional route). At the second step, the annealing was performed at various temperatures in the range of 400 – 520°C for 1 hour. It was found, that additional high-temperature annealing resulted in some reduction in the alloy strength. However, it was quite effective to eliminate the chemical heterogeneity of the cast structure and increase the corrosion resistance maintaining grain size, dispersity and coherency of Al3(Sc, Zr) precipitates.