Effect of melting method and microalloying with rare earths and boron on the quality of low-carbon steel

Effect of separate microalloying with rare earths and boron at optimum version of their introduction on the ingot structure, quality and properties of 20 K cast steel is investigated, as well as effect of melting method - in electric furnaces and in Martin furnaces - on the ingot parameters, change in chemical composition of the metal within the limits of the grade and its properties. Microalloying during the 20 K steel teeming with the rare earths and boron promotes increase of chemical and physical homogeneity of cast metal. Concentration of nitroge sulphur and phosphorus in axial zone of ingot and sulphur zonal liquation considerably decrease during microalloying with the rare earths; dispersion of dendrite structure increases, sulphide impurity decreases, refining from large sulphides and oxides takes place. Gas content and sulphur zonal segregation in the ingot decrease, sulphide impurity and quantity of large inclusions decrease, dispersion of dendrite structure increases with the boron introduction