Non-isothermal annealing of a cold rolled commercial twin roll cast 3003 aluminum alloy

It is shown that the recrystallization behavior of a cold rolled twin roll cast, commercial 3003 aluminum alloy under non-isothermal conditions, can be satisfactorily modeled by combining the approaches developed by Semiatin et al. and Puchi et al. The first approach allows the determination of the apparent activation energy for recrystallization without any ambiguity, information that can then be used in the second approach to define clearly the search range for the value of the apparent activation energy for recrystallization and to determine simultaneously the Avrami constants, from experiments conducted at a single heating rate. It is also shown that the apparent activation energy for recrystallization in this alloy varies between approximately 34 and 79 kJ/mol, with the trend being to find smaller values of this parameter as the strain applied to the material increases. Such low values of this energy were corroborated by isothermal experiments conducted in samples of the same material. The microstructural evolution of the samples annealed under non-isothermal conditions indicates that the rate of growth of the recrystallized grains in the rolling direction is significantly higher that in the short transverse direction, due to the pinning effect of the second phase particles aligned along the rolling direction, which leads to recrystallized structures with an aspect ratio significantly higher than 1. The effect of the strain applied to the material on the recrystallization kinetics is quantified by expressing the time required to achieve a given recrystallized fraction as a function of the effective strain, by a simple parametric relationship that involves three numerical constants. Recrystallization experiments conducted under non-isothermal conditions are found to be more suitable for the evaluation of the effect of the strain applied on the recrystallization kinetics in comparison with isothermal tests, since larger strains can be applied to material before the annealing treatment.