SIMULATION AND CONTROL OF HEAT-TRANSFER IN CONTINUOUS-CASTING OF STEEL

The aim of the present study was to develop numerical models and metho ds by which the strand thermal state could be better controlled. Anoth er purpose was to get a new understanding of the heat extraction from the strand surface and thereby to learn to control the strand cooling better. Different kinds of models were developed: (1) The steady state heat transfer model for calculation of strand temperature field and s hell thickness, (2) the steady state optimization model for calculatin g the optimum secondary cooling pattern so that given metallurgical cr iteria and technological constraints are met, (3) two real-time heat t ransfer models for on-line calculation of strand temperature field and shell thickness, (4) two control models, called Casim and Dyncool, fo r the strand cooling and shell growth, and (5) a model which calculate s the thermophysical material properties of carbon and low-alloyed ste els, taking into account the temperature, the cooling rate, and the co mposition. The first control model, Casim, is based on data tables est ablished in advance by the steady state heat transfer model. The secon d one, Dyncool, is based on the real-time heat transfer model. The pur pose of these models is to retain the selected temperature pattern alo ng the strand in spite of variations in casting parameters. Another po ssible mode is to operate with a constant length of liquid core. Chara cteristics of the models developed and their industrial applications a re discussed in this thesis.