Effect of strain path during cold rolling on the microstructure, texture, and mechanical properties of AA2024 aluminum alloy

Abstract

In this study, the effect of strain path during asymmetric cold rolling process on the microstructure, texture, and mechanical properties of AA2024 aluminum alloy was investigated. Optical microscopy (OM), scanning electron microscopy (SEM), and x-ray diffraction (XRD) were employed to characterize the microstructures and textures. The results showed that the average grain size of cold-rolled samples decreased compared to the as-received AA2024 alloy due to the occurrence of dynamic recrystallization (DRX). The number of DRX grains in the cross-rolled sample was larger than the unidirectional and reverse rolled samples owing to the higher stored strain energy and recrystallization rate of the cross-rolled AA2024. By performing the asymmetric cold rolling in all strain paths, the hardness increased due to increasing the stored strain energy and decreasing the grain size. The hardness and tensile strength of unidirectional and cross-rolled samples was equal. The presence of stronger hard orientations such as [111]∣∣RD in the unidirectional rolled sample compensated its higher grain size and lower stored energy. The overall intensity of components especially hard orientations of cross-rolled sample was much lower than other samples. On the other hand, some new and soft orientations, i.e. [313]∣∣ND and [323]∣∣TD, developed during cross rolling. These resulted in the production of an isotropic AA2024 sheet via asymmetric cross rolling. The fracture mode of deformed samples was a combination of ductile and brittle ruptures owing to increasing the stored strain energy and decreasing the ductility caused by asymmetric cold rolling. However, the contribution of ductile fracture in the cross-rolled sample was higher than the unidirectional and reverse rolled samples.