Nazarenko N. Improvement in quality of continuous casting slabs at the expense of perfection of the temperature-speed mode of teem and terms of secondary cooling

The object of investigation - the processes of solidification, cooling and formation of chemical inhomogeneity of continuously slab billet. The goal of study is the development of processing methods aimed at improving the quality of continuous billet by enhancement the temperature-rate regimes and modes of casting secondary cooling. The scientific innovation includes the following items: a new temperature-rate criterion of crack-resistance , which allows to establish a relationship overheating of the metal in the tundish with the chemical composition and the rate of metal casting , for different groups of steel grades is proposed and tested in industrial conditions; an equation for the estimation of a rational rate of slabs drawing with various cross-sections is received; a new way of the rational temperature profile calculation of the continuous casting slabs surface for reducing slab rejection due to the surface defects is developed; the theoretical approach and the equation for calculating the optimal flow rates in sections of the secondary cooling of CCM, depending on the chemical composition of cast steel, cast metal temperature, pulling rate, the cross sections for improved quality of slab pieces of different grades of steel are proposed and tested in industrial conditions; a method for calculating the distribution of heat of crystallization in the solidification range for low-alloy steels of complex chemical composition is developed. The degree of implementation - the recommendations for preparation and casting of steel in production conditions converter plant JSC "Azovstal" are tested with the expected economic effect of 71 thousand UAH. Scope of use: iron and steel (BOF steel production).