Single Roll Caster to Cast Aluminum Alloy Strip

Abstract

A scraper was developed and attached to a single roll caster to improve the free solidified surface of the as-cast strip. AA5182 aluminum alloy of thickness approximately from 1.5mm to 4 mm was cast at speeds up to 60 m/min. With the scraper, semisolid metal on the free solidified surface was flattened. The pressure of the unit width of the scraper ranged from 0.1 N/mm to 1.0 N/mm and was sufficient to make the free solidified surface flat. Because the strip was solidified on a single side by the single roll caster, center line segregation did not occur. The roll cast strip could be cold rolled down to 1 mm. Visual examination after cold rolling showed no difference between the roll contact surface and the free solidified surface of the strip. The results of tension tests of roll cast and cold rolled strips with the scraper were the same as those of direct chill (DC) cast and rolled strips. A deep drawing test was conducted under two conditions: the roll contact surface was on the outer side, and the free solidified surface was on the outer side. The limited drawing ratio of 1.8 was the same for both conditions. The thickness of the strip was controlled by the roll speed, solidification length (length of the melt pool), and the scraper pressure. The utility of the scraper was shown by the casting of 600 mm width strip. This single roll caster could cast the strip of Al-10mass%Mg which is seemed to be difficult to cast strip without the center segregation by the twin roll caster. The single roll caster is simpler than a twin roll caster. The rigidity for rolling is not a significant concern for the single roll caster. In addition, since the cost of the roll is half that of a twin roll caster, the equipment cost of the single roll caster is more economical.