NON-METALLIC INCLUSIONS IN STEEL PROCESSED WITH MODIFIERS

Abstract

At present, rare earth metals (REM) are widely used in steel production, which have a high affinity for oxygen, sulfur, nitrogen, non-ferrous metals and other impurities. The effect of rare-earth metals is manifested both in a decrease in the content of these impurities in steel and in their transfer from active forms to passive ones, which contributes to the purification of grain boundaries and ensures the formation of a finely dispersed dendritic structure. Purifying steel from harmful impurities, REMs improve its casting properties, fluidity, feeding conditions and crack resistance of castings, and also reduce the anisotropy of the mechanical characteristics of steel. The high efficiency of the influence of REM on the properties of steel is due to their favorable effect on the composition, type, shape, quantity and uniformity of the distribution of the resulting non-metallic inclusions (NI), a significant improvement in the macro- and microstructure of the workpiece, a decrease in its physical and chemical heterogeneity, providing increased density and dispersion of crystalline structures in all areas of the cast billet, including small sections.