Recovery and recrystallization study of an Al-3wt%Mg alloy using a unique combination of quantitative difference-dilatometry and electron backscatter diffraction (EBSD)

Special rolling and heating procedures, as well as the formation, migration and annihilation of dislocations are the cause for a well-defined microstructure, which results in the improvement of the properties of work-hardenable metallic materials. Fundamental knowledge of these processes as well as the microstructure is also of utmost importance for the simulation and modelling of large-scale industrial processes, especially in the aluminum industry.

The main subject of this work is to demonstrate a novel approach of recovery and recrystallisation analysis by combining quantitative difference dilatometry with electron backscatter diffraction (EBSD). The first method enables orientation dependent analysis of the irreversible length/volume change during annealing and the latter enables a broad way of microstructural characterization.

For the present study, the commercial aluminum alloy AW5754 was chosen to examine these annealing processes during linear heating after deformation. Contrary to precipitation hardenable aluminum alloys, this type of alloy does not form a second phase during cooling and is therefore not prone to aging effects.

The combined results gained from dilatometry and EBSD can be used for finding key parameters such as characteristic temperatures, activation energies, and especially changes in the dislocation density that are necessary as input parameters for modelling of recovery and recrystallisation processes.