Isothermal annealing of cold-rolled Al−Mn−Fe−Si alloy with different microchemistry states

Abstract

Microstructural evolution of a cold-rolled Al–Mn–Fe–Si alloy during annealing was studied. Except the as-cast variant, two other different homogenizations were considered, one gave a high density of fine dispersiods providing a considerable Zener drag influencing the softening behavior while the other gave a lower density of coarser dispersoid structure providing a much smaller drag effect. The gradual microstructural evolutions during annealing for the three variants were captured by interrupting annealing at different time. Effects of microchemistry state on recrystallization kinetics, recrystallized grain structure and texture were characterized by EBSD. It is demonstrated that the actual softening kinetics, final microstructure and texture are a result of delicate balance between processing condition and microchemistry state. Strong concurrent precipitation takes place in the case with high concentration of Mn in solid solution, which suppresses nucleation and retards recrystallization and finally leads to grain structure of coarse elongated grains dominated by a P texture component together with a ND-rotated cube component. On the contrary, when solute content of Mn is low and pre-existing dispersoids are relatively coarser, faster recrystallization kinetics is exhibited together with an equiaxed grain structure with mainly cube texture.