Ehishev M. Development of rational compositions of mould powders on the basis of the second offcuts for the higher speed slab continuous casting

Research object - a process of shell formation in crystallisation at the continuous casting of steel with higher speed. Research subject - influence of structure and physico-chemical properties mold powder on slab surface quality and stability of process of steel continuous casting with the higher speed. The purpose experimental and theoretical research of mold powder technological properties, and also their work condition at the slab continuous casting with higher speed (1,4 m/min) for aim of development of mold powder new component compositions on the basis of the domestic secondary offcuts. Methods - research computation and experimental methods of physico-chemical and thermophysical properties of mold powder and flux. Novelty - the measuring method of slag viscosity is improved by creation of viscometer on the basis of microcontroller of ATMEGA8; the new simplified method of determining the cristalline phase amount in solid slag is developed; at the first time functional relationship between a solidification begining temperature and crystalline phase content in solid slags is set; got subsequent development of picture about influence of mold powder technological properties on surface quality of continuous semis. Results - the electrorotary method of slags viscosity measuring is got subsequent development; the simplified method of determining the crystalline phase amount in the solid mold flux is developed; it was set, that viscosity and solidification begining temperature depend on not only chemical composition of mold flux but also from cooling speed of slag melt; shell sticker with subsequent break-out formation at high hydrogen content in a metal is the result of influence of complex negative factors: obstruction of liquid slag flow into a mold-shell gap because of achievement of equality of hydrogen partial pressure in a gap to atmospheric pressure, porosity of slag structure in a mold-shell gap reduces heat-transfer from a semis to the mold and slows shell growth, low shell strength because of its porous structure and insufficient (from point of shell strength) thickness; experiment planning operation allowed to develop component compositions of mold powder with the necessary level of technological properties;use of the mold powder recommended to application in the conditions of "Alchevsk Steel Plant" allowed to get an economic effect ~ 2 UAH/t of steel. Sphere of use - ferrous metallurgy (steel continuous casting).