Investigation of recrystallization processes in aluminum alloys - in situ electron backscatter diffraction optimized for annealing at constant heating rates

To characterize recrystallization processes in aluminum alloys, in situ electron backscatter diffraction (EBSD) has been optimized for operation at constant heating rates, as opposed to more conventional methods such as isothermal annealing. The core of the method, which enables heating rates of up to 10 K/min with existing equipment, is based on optimized acquisition parameters and an improved evaluation strategy of the EBSD scans. The developed method was used to investigate the recrystallization process during heat treatments of cold rolled aluminum sheets. The collected EBSD data were used to extract the kinetic curves of recrystallization, and their dependence on heating rate, deformation state, and alloy is shown. Concurrent precipitation was observed in one alloy, and its effect on recrystallization behavior is discussed. In further
evaluations, the evolution of texture with emphasis on the cube component during the recrystallization process was studied. One finding was that in a 6xxx series alloy, cube grains form preferentially at early stages of the recrystallization process.