Recrystallization during hot deformation of aluminium alloys

Abstract

The influence of alloying additions upon the annealing behaviour of aluminium after cold working and during hot working was studied. It is shown that alloying additions, such as magnesium or zinc, that are present in solid solution in the aluminium throughout processing, result in a reduction in the static recrystallization temperature after cold working and can result in dynamic recrystallization during hot working. Textural intensity ratio measurements imply that the alloying additions have significantly reduced the stacking fault energy compared with that of pure aluminium. Alloying additions with low solubility and low diffusion rates in aluminium can give dispersions of fine-scale precipitate particles that virtually inhibit static recrystallization after cold working. The combination of an element in solid solution to encourage dynamic recrystallization with an element, such as zirconium, to produce a dispersion of fine particles, results in alloys that recrystallize dynamically but in which grain growth is restricted by the dispersion. Superplastic deformation of these alloys is then possible.