Solidification and cooling of a continuously cast steel slab and the simultaneous heating of the mould is a very complicated problem of transient heat and mass transfer. This is described by the Fourier-Kirchhoff equation and the temperature field of the mould is described by the Fourier equation. Such a problem cannot be solved without a numerical model of the temperature field - of the actual concasting while it is passing through the concasting machine (CCM) and the mould. The paper discusses the application of a three-dimensional (3D) numerical model of the temperature field of a solidifying concasting. A very important part of the analysis is to determine the necessary parameters on an actual CCM during production. The investigation focuses mainly on determining the temperature in the tundish, the temperatures of the walls of the mould, on the surface temperatures of the slab under the mould (measured by means of pyrometers), the surface temperatures within the tertiary cooling zone (measured by means of thermocouples) and on determining the metallurgical length of the concast slab using the radio-isotope method. The cooling intensity of individual cooling jets has to be conducted on an experimental laboratory device. Each jet is measured separately on a hot plate-model simulating the surface of the slab, which is cooled by a moving jet. The temperatures measured beneath the surface of the modelling plate by means of thermocouples are converted to cooling intensities (using an inverse task), which, in turn, are converted to the courses of the heat transfer coefficients using an expanded numerical model. This laboratory facility is also capable of measuring the effect of radiation which is dependent not only on the surface temperature but also on its surface quality. Experimental research and measurement must be conducted not only to confront them with the numerical model, but also to make the model more accurate throughout the process. The comparison of the results (attained from the computed and from the experimentally measured temperature field of a 1530×250 mm steel slab) is very satisfactory. This analysis was conducted using a program devised within the framework of the GA CR project (No. 106/01/1464, 106/01/1164, No.106/01/0379 and No. 106/01/0382), of the COST-APOMAT-OC526.10, EUREKA No.2716 COOP and KONTAKT No. 2001/015 programmes.
展开▼
