Strain rate effects on microstructure and texture evolution in cold-sheared Al-6 Mg alloys during low-temperature annealing

Abstract This study examined the effects of the strain rate on the texture evolution of Al-6Mg alloys over one hour of annealing at 300 °C. Three different strain rates of 0.1 s−1, 1 s−1, and 10 s−1 were applied to the samples using a torsion tester. Considerable grain growth was observed in the 0.1 s−1 cold-sheared sample during one hour of annealing. The growth of B/ B - and C-oriented grains can explain the grain coarsening behavior. The conventional grain growth, nucleation, and subsequent grain growth, plausibly describe the grain size evolution of those 1 s−1 and 10 s−1 cold-sheared samples during annealing. A textural transition from brass-type to copper-type was evident during the annealing process of the 1 s−1 cold-sheared sample. On the other hand, the brass-type texture bias in the 10 s−1 cold-sheared sample increased gradually over one hour of annealing. The copper-type texture generally evolved under the 0.1 s−1 cold-sheared condition. Generally, the misorientation indices (= M-index) of all three cold-sheared samples were decreased by extending the annealing time. A smaller M-index indicates stronger texture anisotropy. Although the M-index was higher in the 0.1 s−1 and 10 s−1 cold-sheared samples than the 1 s−1 sample throughout the annealing process, the M-index of the 0.1 s−1 sample eventually became the lowest among the three conditions under the fully annealed condition.