Volgograd State Technical University, Volgograd, Russia
N. A. Zyuban, Dr. Eng., Prof., Dept. of Technology of Materials, e-mail: tecmat49@vstu.ru
D. V. Rutskii, Cand. Eng., Associate Prof., Head of the Dept. of Technology of Materials, e-mail: drutskii@vstu.ru
M. S. Nikitin, Graduate Student, Dept. of Metal Technology
M. V. Kirilichev, Head of the Laboratory of the Dept. of Technology of Materials, e-mail: tecmat@vstu.ru

One of the main technological parameters affecting the cost of production of continuously cast billets is the pourability of steel on continuous casting machines. There is a problem of low serial casting of C45E grade sulfur-containing steel in the EFMS of VTZ JSC, which is associated with an unstable casting process of this steel grade. The instability of the process is explained by the formation of outgrowths from non-metallic inclusions deposited on the inner walls of the dosing nozzles and submersible nozzles and preventing the metal from passing into the mold space from the tundish. In order to determine the thermal and temporal nature of the release of non-metallic inclusions deposited on the walls of steel-pouring channels, a study was made of the contamination of steel with non-metallic inclusions at various stages of the steelmaking process (out-of-furnace treatment – degassing – continuous casting) using optical (Leica 8 C) and electron microscopy (FEI Versa 3D). The phase composition of the inclusions was determined by recalculating the EDS analysis data in the Thermocalc software package. It has been established that non-metallic inclusions at all stages of processing have an identical chemical and phase composition and are represented by silicates, aluminates, calcium aluminates of the type m(CaO)∙n(Al₂O₃) of different stoichiometric composition, sulfides MnS and CaS, complex oxysulfides. The use of calcium to modify non-metallic inclusions leads to the formation of calcium aluminates, refractory for this steel grade, and CaS sulfide inclusions, deposited on the walls of the steel-pouring channels during the continuous casting of steel. The share of sulfide inclusions at the end of outof-furnace treatment is about 50–80% of the total number of inclusions.

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