THE EFFECT OF ELECTROMAGNETIC STIRRING ON THE CRYSTALLIZATION OF CONCAST BILLETS - II.

摘要

The solidification and cooling of a continuously cast slab and the simultaneous heating of the mold is a very complicated problem of three-dimensional (3D) transient heat and mass transfer. The solving of such a problem is impossible without numerical models of the temperature field of the concasting processed through the concasting machine. Experimental research and measurements have to take place simultaneously with the numerical computation, to be confronted with the numerical model and make it more accurate throughout the process. An important area of the caster is the secondary cooling zone, which is subdivided into thirteen sections. In this zone, where the slab is beginning to straighten, the breakout of the shell can occur at points of increased local chemical and temperature heterogeneity for the steel, from increased tension as a result of the bending of the slab and also from a high local concentration of non-metal and slag inclusions. The changes in the chemical composition of the steel during the actual concasting are particularly dangerous. In the case of two melts, one immediately after the other, this could lead to an immediate interruption in the concasting and a breakout. The material, physical, chemical and technological parameters, which differed in both melts, were determined. If the dimensionless analysis is applied for assessing and reducing the number of these parameters, then it is possible to express the level of risk of the breakout as a function of five dimensionless criteria.