Optimization of the Composition and Amount of Nonmetallic Inclusions in a Continuously Cast Billet Based on the Deoxidation of the Melt with Aluminum and Calcium Carbide

The methods of optical and electron microscopies are used to estimate the degree of contamination of D carbon steel with nonmetallic inclusions in samples taken in all stages of steelmaking at the electrosmelting workshop of the Volzhskii Piping Factory. The procedure of smelting was carried out by using the following technology: production of semifinished products in the electric arc furnace → processing of the melt in devices for out-of-furnace treatment → continuous casting. We determine the degree of contamination of steel and the chemical composition of nonmetallic inclusions in the samples for two different procedures of deoxidation: with the AB-87 aluminum and CaC 2 deoxidizers. It is shown that calcium carbide positively affects the chemical composition of steel and the process of formation of nonmetallic inclusions and leads to the modification of corundum inclusions, and their globularization in the initial stages of steelmaking. The favorable shape of the inclusions formed in the initial stages of the out-of-furnace treatment is preserved in the subsequent stages, which facilitates their efficient removal. The application of CaC 2 as a deoxidizer makes it possible to produce continuously casted billets with a twice lower degree of contamination with nonmetallic inclusions.