AB-INITIO PREDICTIONS OF INTERFACIAL HEAT FLOWS DURING THE HIGH SPEED THIN STRIP CASTING OF METALS AND ALLOYS

摘要

The purpose of this study was to develop ab-initio mathematical and computational models, aimed at predicting instantaneous heat fluxes when a liquid metal or alloy contacts a colder substrate. Semi-analytical and fully computational models have been developed to determine whether measured instantaneous heat fluxes associated with the strip casting of aluminum alloys on copper and steel substrates can be inferred from first principles. It is shown that the thermal properties of the melt, substrate and entrapped gas films, are critical in determining the peak heat fluxes achieved during metal/mould contact, a cold copper substrate being more effective than steel in that regard. The surface texture of a belt and the presence of gas, and or liquid/solid films among the "valleys" between the peaks (where perfect thermal with the substrate contact is assumed), is also shown to be of great significance. The computational models developed allow various scenarios to be effectively studied, and experimental curves matched with "predicted" curves based on reasonable assumptions. The use of such models can help guide operators of near-net shape casting machines in their quest to effectively control interfacial heat fluxes during the formation of sheet products.