High speed strip casting of light metal alloy sheet materials

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The production of aluminum sheet is presently a highly energy intensive operation, of low productivity relative to equivalent steelmaking operations. Since aluminum has the advantage of being a lighter weight material vs steel, the use of aluminum in the transportation industries is to be desired since energy requirements associated with lightweight vehicles can be significantly reduced vs steel structures of equivalent thickness, over a vehicle's lifetime. The move from DC (direct chill) casting of aluminum ingots to the production of thin sheets of aluminum on a horizontal single belt caster offers the possibility of significantly reduced energy consumption during annealing and hot rolling operations, reduced capital costs, and reduced operating costs. The Horizontal Single Belt Casting Facility(HSBC)installed in the laboratories of the MMPC will be used to test the scientific and industrial feasibility of this new casting process. The specific objectives of this research program are to investigate the production and properties of continuously cast sheets of aluminum (AA6111) and magnesium alloys (AM60), using the pilot scale HSBC. This is a commercially promising, near-net shape casting operation, in which liquid metal is iso-kinetically delivered onto a water-cooled, moving substrate, to produce strips of material, 2-4mm thick, at speeds of up to 1m/s. A major difference from the customary twin-roll and twin belt casters presently used in the Light Metals Industries, is an order of magnitude increase in casting speeds. Virtually all the sensible heat needed to solidify the melt is removed downwards (uni-directional solidification), while the strip itself remains unconstrained as it forms. Based on simulations to date, many factors influence the quality of the strip that can be produced. These include alloy composition and freezing range, latent heat, superheat, shrinkage, substrate material (copper/steel belt), belt coatings, gas atmosphere, alloy composition, mode of metal delivery, chemical reactions, gas films, lubricating films, surface texture, surface tension, meniscus behaviour, interfacial turbulence, and wetting.