Investigation on Reduced Aging Time and Enhanced Tensile Properties of Al-Mg-Si Sheets by Asymmetric Cryorolling

The automotive and other industrial fields make extensive use of Al-Mg-Si alloys, and the asymmetric cryorolling (ACR) employed has the potential for large-scale industrial applications and energy conversation because it is conducive to grain refinement and suppression of dynamic recovery during rolling. In this study, Al-Mg-Si sheets underwent asymmetric rolling (AR) and ACR. The ACR sheets were subsequently treated with artificial aging at 160°C for 2 h (ACR-2h), achieving peak mechanical properties significantly faster than the 10 h required for AR sheets (AR-10h). ACR accelerated the precipitation kinetics, which was related to the inhibition of dislocation motion by the cryogenic temperature and the enhancement of dislocation density. The ACR-2h sheets exhibited the highest yield strength, ultimate tensile strength (350 MPa and 363 MPa, respectively), and elongation (11%) in comparison to AR-processed and original sheets. Compared to solution-treated (ST) and the AR-10h samples, the ACR-2h samples showed a 64% and 26% reduction in grain size, respectively. Furthermore, the ACR-2h dislocation density was 33% higher than the AR-10h samples, which was beneficial for the improvement of the mechanical properties. Additionally, small and dense β" precipitates were observed, further enhancing strength and elongation.