Metal-mould interfacial heat transfer during solidification of cast iron against cast iron chills

Abstract

Heat transfer during the unidirectional solidification of a cast iron alloy against cast iron chills was investigated using an inverse modelling approach. Chills of thickness 100 mm and 10 mm were used, to simulate gravity die casting conditions and the use of chills in sand moulds. In both cases transient heat transfer, measured by the interfacial heat flux and heat transfer coefficient, declined from initially high values in the first few seconds of solidification, to values about an order of magnitude lower which persisted for the remainder of the experiments. In the case of the thin chill it became saturated with heat until it was no longer in a position to extract further heat from the casting. These results were interpreted by studying the resistance to heat transfer from the casting offered by the casting-chill interface and the chill itself. For example, the thermal resistance of the casting-chill interface can be influenced by the deformation of their respective surfaces and their subsequent relationship.