Twin roll casting of aluminum alloy strips

Abstract

Two kinds of twin roll caster for aluminum alloys were devised in the present study. Vertical type was adopted. The strip, which was thinner than 3mm, could be cast at speeds higher than 60m/min. Aluminum alloy, which freezing zone is very wide like A5182, could be cast using the twin roll caster of the present study at speeds up to 150m/min. Features of the twin roll casters are as below. Copper rolls were used and lubricant was not used in order to increase the casting speed. Heat transfer between melt and the roll was improved by hydrostatic pressure of the melt. Separating force was very small in order to prevent sticking of the strip to the roll. Low superheat casting was carried out in order to improve microstructure of the strip. A5182 strip, which had equiaxed structure, could be cast. Some heat treatment was tried and tested in order to improve the mechanical property of A5182 strip. A3003 strip was cast by low superheat strip casting. A3003 strip showed thermo-softening resistance. Semisolid strip casting of A356 alloy was tried using a twin roll caster equipped with a cooling slope. Mechanical property, especially elongation, was improved. Result of 180° bending test was improved, too. Semisolid strip casting was useful for high speed roll casting, and the casting speed increased up to 180m/min.