Influence of alloy chemistry on the deformation behaviour and anisotropic properties of aluminium ultra-fine-grained thin sheets

In the present work, cryorolling was performed on both pure Al (AA1070) and Al-Mg alloy (AA5083). Cryorolled materials were subjected to same level thermal treatment. The deformation behaviour and anisotropic properties of these materials were extracted from uniaxial tensile test results. These properties were compared for base, cryorolled and heat treated conditions for both the materials. Compared to AA1070, AA5083 shows much improved strain hardening capability. This is attributed to its lower stacking fault energy and influence of incoherent Mg solute in the Al matrix. By controlled thermal treatment substantial ductility was also regained for AA5083, without much loss in its tensile strength. This behaviour is attributed to the presence of bimodal microstructure in AA5083, consisting of ultra-fine as well as coarse grains. Due to the preservation of rolling texture even at high annealing temperature, the anisotropic properties were also found to be much favourable in case of AA5083.