MOLD SURFACE-ROUGHNESS AND INTERFACIAL HEAT-TRANSFER USING HEAT-FLOW MODEL

The heat resistance at the metal/mould interface, represented by the i nterfacial heat transfer coefficient (IHTC), plays an important role i n the rate of heat transfer from the metal to the mould. The objective of the present work was to determine the influence of the mould inner surface roughness on the IHTC using steel moulds of diameter 55 mm an d height 56 mm with different surface roughnesses to solidify pure zin c with a superheat of 80 K. A computer program solving the heat conduc tion equation taking into consideration the convection in the molten z inc was used, together with the experimental temperature history to de termine the IHTC at the metal/mould interface. The results show that I HTC IHTC decreases as mould surface roughness increases. (C) 1997 The Institute of Materials.