Recovery of AlMg alloys: Flow stress and strain-hardening properties

The recovery of Al-2.5 wt% Mg alloys cold-rolled to several strains between 0.1 and 3 has been studied essentially using tensile tests. The yield stre ss and strain-hardening properties are studied as a function of the initial prestrain, and of the temperature and the duration of annealing treatments . A theoretical model based on the dislocation structure is proposed. The k inetic evolution of the yield stress is related to the variation of the tot al dislocation density as a single structural parameter. The pseudo-logarit hmic time decay is explained on the basis of a relaxation of the internal s tresses by thermally activated dislocation motion. A strain-hardening model is proposed based on Kocks' constitutive law of plasticity, where the disl ocation storage and dislocation annihilation parameters are adapted to a he terogeneous cell/subgrain dislocation structure. The adjustment of the mode l to the work-hardening behaviour is in agreement with TEM observations. (C ) 1998 Acta Metallurgica Inc. Published by Elsevier Science Ltd. AII rights reserved.