Continuous Casting of Thin Sheet Aluminum Alloy A7075 at Low Speed and High Pressure Using a Vertical Twin Roll Caster

Abstract

This paper reports on the vertical twin roll casting of aluminum alloy A7075. Aluminum alloy A7075 belongs to the highest strength alloys and its sheets are produced by rolling and extrusion. Although A7075 is used in the aerospace industry and for special applications, it has a high susceptibility to solidification cracking and is difficult to obtain sheets easily. Twin-roll casting can produce thin sheets directly from molten metal, making it possible to produce sheets other than conventional sheet alloys. In this study, experiments were conducted using a miniaturized apparatus to study the continuous casting of A7075 thin plates under low-speed and high-pressure conditions suitable for continuous casting of A7075. Because of the smaller size and narrower roll width of this equipment, an increase in load per unit width is expected. The effects of roll speed on sheet continuity, surface properties, thickness, microstructure, and Vickers hardness were investigated. Experiments were conducted under five conditions of roll peripheral speeds of 1, 3, 5, 7, and 10 m/min. Thin sheet fabrication was possible under all conditions except 1 m/min in this experiment, and thin sheet fabrication of aluminum alloy A7075 by vertical twin roll casting was feasible.