Ukhin V. Justification and improvement of continuous casting process technological parameters at high-productivity billet caster.

Object - the processes of billet solidification and formation in the highly productive billet caster mold and their influence on the ingot's quality and casting stability. Objective -justification of process variables of continuous casting on highly productive billet casters. Research methods and equipment - physical simulation of processes of billet solidification and mechanical deformation in the mold with regard for the main points of metals crystallization theory, heat-and-mass transfer theory and the theory of similarity, mathematical statistics methods, mathematical simulation of temperature fields distribution and internal stresses formation in the solid skin with the help of computer. Theoretical and practical results - there was solved the urgent scientific and technical problem of theoretical justification and improvement of casting speed mode on highly productive billet caster, that gave the opportunity to prevent the formation of surface and subsurface cracks and defects of billet geometry by means of improving the ingot's solid shell and the mold tube contact, to reduce the number of breakouts caused by the cracking phenomenon for 15%, to increase the yield for 0,02% and the billet caster productivity in conditions of "Electrostal" LTD for 10%. Novelty: for the first time by the experimental methods there was established the fact of the skin deformation sphere moving from the band, which is near the ingot's corner, to the centre of the face with the extension of the solidified layer thickness from 2,5 mm to 9 mm; it was established for the first time that surface cracks appeared in the continuously casted billet, which were the reason of the breakouts, due to the deformation of the ingot's section, which had been caused by the alternate decrease and increase of the billet rhomboidity value, which was about 1-2 mm and more; it was inferred for the first time that the billet skin in the mold began to come off from the mold tube wall in the distance from the metal meniscus, which depended on the steel casting speed in direct proportion and corresponded to the point, in which the solidified shell thickness was 5-7 mm; it was established that dusting billet crystal structure formation in the mould the separate crystals growth speeds differed from each other for 25-35% and the dendrite growth direction in most cases was chaotic relative to the heat transfer surface that cause formation of local regions with 40-60% of liquid phase that reduces the skin mechanical strength. Introduction extent - the recommendations were adopted in conditions of "Electrostal"LTD (the town of Kurakhovo) in steel casting on the highly productive billet caster.The sphere of usage - metallurgy.