Quantitative Comparison of the Recrystallization Kinetics of Two Industrially Processed 5xxx Aluminum Alloys

The annealing kinetics of cold-rolled AA5182 and AA5657 aluminum alloy sheets have been investigated and compared. The microstructures of a series of partially recrystallized samples are characterized by electron back scattered diffraction and key stereological parameters including volume fraction recrystallized, interfacial areas and contiguity are determined. The overall recrystallization kinetics as well as the nucleation and growth rates are thereby quantified. The results reveal that the nuclei develop in clusters. This matches well with the observation of a low kinetics exponent n = 2 in AA5182. Much more surprising is that n is 2.8 in AA5657, even though the nucleation is clustered. Also, it is higher than almost all recrystallization kinetics investigations which generally find values significantly below 3. Effects of nucleation rate, spatial distribution of nuclei and growth rate are discussed and used in a quantitative analysis of recrystallization kinetics in the two alloys.