INFLUENCE OF THE HOT-ROLLING TECHNIQUE FOR EN AW-8021B ALUMINIUM ALLOY ON THE MICROSTRUCTURAL PROPERTIES OF A COLD-ROLLED FOIL

In the whole manufacturing chain of aluminium products, hot rolling significantly impacts the obtaining of favourable microstructures and desired mechanical properties of final products. The determination of crucial differences between the reverse hot rolling on a single-stand mill and the tandem hot rolling on a tandem-stand mill presented a major challenge. Besides the grain-size distribution in the microstructure's cross-section, the crystallographic textures of hot-rolled strips were also determined and compared. The alternating band areas of a coarse-grained microstructure and fine-grained microstructure due to reverse hot rolling and, especially, the appearance of extremely fine grains on the surfaces present limitations compared to the tandem hot rolling. For subsequently cold-rolled foils, classical mechanical properties were measured. Besides, the usefulness of EN AW-8021B foils with a thickness of 60 mu m for pharmaceutical-packaging applications was tested with a burst test. A minor but important difference of 1 % in the elongation is shown for the convex height increased by 1 mm.