Vol.10, No3, 2010, pp.215-218
UDC  621.746.6 : 669.14

The quality of continuously cast steel is determined by the conditions existing during cooling and solidification of the steel. One of the causes of crack formation on the blocks in the continuous casting process is the cyclic recurrence of cooling. The periodicity of cooling depends on the distance between spray jets. Thermal and mechanical stresses acting on this shell can lead to crack formation and result in poor quality of the final steel product and to operational problems with the casting machine. The requirements for quality of blooms can be achieved by reducing spray water volume in the secondary cooling zone. Thus reduction of cooling intensity is limited by the height of the installation and distance between rollers. An investigation has been carried out on the operating and cooling parameters of a radial continuous bloom casting machine. A real time two-dimensional finite difference thermal model describing the solidification, bulging behaviour and metal stress state is used for calculation of temperature distribution and shell thickness during casting. Additional limitations are introduced in connection with the cooling rate on the block surface and the warm-up temperature after the block leaves the secondary cooling zone. The required heat transfer coefficients on the block surface that comply with the above-indicated requirements are determined. Results for thermocyclic recurrence along the block axis and surface areas, which shall be covered by water cooling jets, are obtained.

Keywords: continuous casting, cracks formation, heat transfer, solidification, mathematical modelling