Recovery quantification and onset of recrystallization in aluminium alloys

Abstract

Novel forming processes for light metal alloys utilize recovery and recrystallization to extend their total elongation and enhance formability. To attain optimum efficiency in such processes, it is necessary to understand and quantify the kinetics of recovery and recrystallization in work-hardened metal alloys. An electron backscatter diffraction based method, using local average orientation spread, is shown to identify the end of recovery as well as the onset of recrystallization. Local average orientation spread results from dislocation flux and storage during plastic deformation and hence, captures the evolution of static recovery process. The method has been demonstrated using pre-strained Al–Mg alloys. The recovery kinetics is shown to be consistent with results from dislocation density based recovery models. In addition, a direct observation of the coexistence of static recrystallization and recovery illustrates competing processes for energy minimization.