Advanced methods for an improved mould heat transfer control

This multinational research project aimed at the correlation of the essential parameters and to elaborate concrete process engineering measures for an improved mould heat transfer control. The research was carried out in close collaboration between the steel plants Dillinger Hüttenwerke, Sidenor, Cogne Acciai Speciali, and the research institutes Centro Sviluppo Materiali and Betriebsforschungsinstitut as co-ordinator. Experimental, analytical and numerical tools were used to conduct research on cooling systems in slab casting moulds, transient thermocouple readings, mould powder properties, phase transformation during solidification, surface quality, friction forces, local and global heat withdrawal from slabs and billets. The resulting finding were correlated with process conditions. The effect of a vast variety of parameters on heat transfer and product surface quality were established. Heat flux assessment by use one instead of a pair of thermocouples in the mould wall is applicable with a sufficient reliability of results using numerical models for the determination of heat flux density. For slabs and billets there were significant correlation between process parameters, heat flux density and surface quality. Since there is strong interaction between the investigated parameters it is difficult to determine what is cause and what the effect. Mould heat flux density is affected by the interaction of different parameters. Therefore it cannot be applied for process control itself but is an excellent mean for off- and online process observation. This is one of the important out-comes of the project. Correlation was found for mould powder properties and friction which in turn can be assigned to the surface quality of billets. Indices for process quality and product quality were derived for the purpose of controlling the casting process by friction force measurements.