Transverse mechanical properties and microstructure of 1500 mm wide AZ31 magnesium alloy plate and its evolution during industrial rolling

The 1500 mm-wide AZ31 magnesium alloy plate is an important material for the molding of large shell components.In the industrial rolling process, the wider the plate, the more uneven the temperature and stress distribution are in the width direction during the industrial rolling process, which results in poor mechanical properties and an uneven microstructure. In this paper, the mechanical properties and microstructure evolution along the width direction during a single-pass rolling process (6–3 mm) of this plate were qualitatively and quantitatively investigated. Additionally, a cellular automaton (CA) model was used to reproduce the grain distribution along the width direction. The result shows that there is a significant difference in the elongation of different parts of the plates along the wide direction, and the elongation of the center part is significantly higher than the edge, which is related to the uneven microstructure distribution. The average grain size from the edge to the center shows a tendency of increase and then decrease, and the degree of grain refinement has increased. The number of twins increased in the edge part, showing a typical mixed grain state with poor unevenness. Further CA shows that the average grain size and percentage of dynamic recrystallization increase and then decrease from the center to the edge. The parts 0–250 mm and 625–700 mm from the edge are fine-grained (average grain size less than 1 μm) and account for about 46 % of the plate. These parts are preferred for the subsequent further processing of rolled plates.