Tailoring microstructure and texture of annealed Al-Mn alloy through the variation of homogenization and prior cold deformation strain

Abstract

The grain structures and crystallographic textures desired for various applications of aluminium alloys are usually modified by recrystallization during annealing. In this study, the interactions between recrystallization and precipitation were investigated using the same Al-Mn alloy but with different homogenization procedures (which gives different microchemistries in terms of solute level and second phase particle state) and prior cold deformation strains, both of which are easy to realize in industrial practice. The results show that recrystallization and precipitation kinetics are both promoted at large deformations but their mutual interactions also exist. Recrystallization is retarded by precipitation through the suppressing of nucleation and pinning of grain boundary migration, while early finish of recrystallization delays precipitation by reducing their nucleation sites. The delicate interplay between recrystallization and precipitation during annealing leads to different combinations of grain structures and textures. An equiaxed fine grain structure can be obtained when recrystallization is not affected by fine particles while the combined effects of a strong fibrous deformation structure, suppressed nucleation of recrystallization and preferential growth lead to a coarse elongated grain structure. Different crystallographic textures desired for typical applications of Al-Mn alloys can be obtained after annealing simply through the different combinations of homogenization procedures and prior cold deformations.