Effects of homogenization treatment on recrystallization behavior of 7150 aluminum sheet during post-rolling annealing

The effects of two homogenization treatments applied to the direct chill (DC) cast billet on the recrystallization behavior in 7150 aluminum alloy during post-rolling annealing have been investigated using the electron backscatter diffraction (EBSD) technique. Following hot and cold rolling to the sheet, measured orientation maps, the recrystallization fraction and grain size, the misorientation angle and the subgrain size were used to characterize the recovery and recrystallization processes at different annealing temperatures. The results were compared between the conventional one-step homogenization and the new two-step homogenization, with the first step being pretreated at 250°C. Al3Zr dispersoids with higher densities and smaller sizes were obtained after the two-step homogenization, which strongly retarded subgrain/grain boundary mobility and inhibited recrystallization. Compared with the conventional one-step homogenized samples, a significantly lower recrystallized fraction and a smaller recrystallized grain size were obtained under all annealing conditions after cold rolling in the two-step homogenized samples. •Effects of two homogenization treatments on recrystallization in 7150 Al sheets•Quantitative study on the recrystallization evolution during post-rolling annealing•Al3Zr dispersoids with higher densities and smaller sizes after two-step treatment•Higher recrystallization resistance of 7150 sheets with two-step homogenization