Microstructure evolution in hot worked and annealed magnesium alloy AZ31

The present work examines the microstructure that evolves during the annealing of hot worked magnesium alloy AZ31. First, the influences of deformation and annealing conditions on the microstructures are assessed. It is found that the annealing behaviour is consistent with what one would expect for a recrystallization type reaction. Whilst both the deformation and annealing conditions influence the time required to reach a stable annealed microstructure, the grain size attained is governed solely by the prior deformation conditions employed. At the highest temperature and strain rate examined, the rate of recrystallization is quite high and the grain size was found to be approximately double when annealed for only 1 s prior to quenching. Finally, semi-empirical equations are developed to predict the kinetics of recrystallization, as well as the evolution of grain size, during annealing.