Structural transformations in continuously cast Al-Mg alloys

Four continuously cast Al-Mg alloys were cold rolled and annealed by slow heating from room temperature (RT) to 500 deg. C. The influence of solute elements (Mg, Mn, Fe, Si and Cr) on recovery, recrystallization and precipitation was studied by electrical resistivity measurements, light and transmission electron microscopy (TEM) and X-ray analysis. TEM observations proved that deformation recovery occurs during cold rolling and is strongly influenced by the amount of solute atoms, particularly Mg. The most intensive electrical resistivity changes were observed at temperatures above 400 deg. C. TEM examinations indicated that they correspond to precipitation. Solute atoms, namely Mn, Fe, Si and Cr, significantly hinder recrystallization. Precipitation of non-coherent precipitates occurs upon annealing. The presence of Mn, Fe and Si was detected in the fine precipitates by EDAX X-ray analysis