Grain refinement of 5083 based aluminum alloy sheets by warm rolling

An attempt was made to refine the grain structure of the 5083 based aluminum alloy containing Zn, Cu and Zr, by employing a new warm rolling method under the control of both roll temperature and material temperature. Samples were rolled at temperature ranging from 200°C to 400°C with re-heating after each rolling pass in order to keep sample temperature. As rolling temperature gets higher, the subgrain structure becomes more stable. In the case of rolling at 400°C, fine grains with diameter less than 3 μm are observed after final annealing. It is also found that the sheet rolled at 400°C has a high ratio of low angle boundaries, less than 15°, after final annealing. On the other hand, the sheets rolled at below 250°C show a fully recrystallized structure. The warm-rolled sheets have strong β-fiber orientations. There is no apparent change caused by the subsequent annealing in the orientation density of the β-fiber in the sheet rolled at 400°C. The yield strength of a sheet in O-temper rolled at 400°C is 40% higher than that of a cold rolled sheet.