Sub-grain Boundary Mobility of 6XXX Alloys during Annealing

Abstract

In this paper, 6061 aluminum alloy and a new type of dispersion-strengthened 6XXX aluminum alloy (named WQ) were compressed to a true strain of 1.2 at a strain rate of 0.1/s at 300/400/500°C and then annealed at different temperatures. The microstructure evolution of both heat treated alloys were characterized by EBSD. The results showed that during the annealing process of the two deformed alloys, the sub-grain size did not increase significantly. Due to the pinning effect of the dispersoids in WQ alloy, the sub-grain size of WQ was smaller than that of 6061 alloy. Under the same deformation conditions and annealing process, the deformation stored energy of WQ alloy was higher than that of 6061 alloy. The deformation stored energy of 6061 compressed alloy was more sensitive to the annealing temperature. Combining theoretical formulas and EBSD data, the sub-grain boundary migration rate curves of 6061 and WQ deformed alloys during the annealing process were obtained, which could provide a theoretical basis for the future study of the sub-grain growth process of multi-element aluminum alloys.