Continuous Roll Casting of Aluminium Alloys– Casting Parameters Analysis

The continuous roll casting process (CRC), consisting of continuous strip casting between rolls, is now well known. It was introduced by the SCAL Company (Pechiney Ugine Kuhlmann Group) 60 years ago 1 . The process consists of solidifying aluminum or aluminum alloys between the water-cooled rolls of a duo rolling mill. From the moment when solidification is completed to the moment when the strip is no longer in contact with the rolls, aluminum is submitted to reduction leading to hot working which is essential for the final quality of the product 1, 2 . The cast strip is produced horizontally out of the caster and is directly coiled while it is still hot. The size of the coil is adapted to the cold rolling operation. The strip thickness ranges from 4 to 12 mm. Figure 1 shows the principle of the CRC process 1-4 . In the aluminum continuous roll casting process (Figure 1), both solidification and deformation are completed in a narrow gap between a pair of opposite rotating rolls. Therefore, the valid zone of this process is the solidification-deformation zone in the roll gap. Conventional twin-roll casters for aluminum alloy have steel rolls, which have a separating force of 2,5-5·10 kN/mm. Lubricant is sprayed on the rolls to prevent the strip from sticking to the roll. The molten metal solidifies against the roll and is immediately hot-rolled into the solid strip 1, 2, 5, 6 . In order to produce flow disturbance in the aluminum melt at the solidification front, while keeping the stability of rheological interface, the configuration and parameters of this zone are determined through experiment and theoretical analysis. The testing materials are Al99,2 (AA1235) and Al99,5 (AA8011) aluminum alloys. Their chemical composition measures up to the international deformation aluminum alloys standard. All these materials are able to form coarse crystals in the roll-casting process. The Al-Ti-B grain refiner in a form of wire was applied. This original process, attractive for its well-known operating simplicity was able to cast strips of about 1 to 2 m wide.