STUDY OF THE INFLUENCE OF THE Si/Mn CONTENT RATIO ON THE DENDRITIC STRUCTURE OF STEELS FOR RAILWAY AXLES

Abstract

Purpose. Investigation of the effect of different total concentration and ratio of Si and Mn content on the dendritic structure and segregation inhomogeneity of cast carbon steel and its transformation after hot plastic deformation. Methods of research. To determine the effect of the content of Si and Mn, experimental ingots with a variable chemical composition within the grade were made for three steel grades used for the manufacture of railway axles – grade OS according to DSTU 31334, F according to AAR M 101 and EA1N according to EN 13261. To determine the dendritic structure microstructural analysis was used after etching in sodium picrate. Results. A comparative analysis of the microstructure of the experimental heats of steels with a variable chemical composition has been carried out. The ratio of content in steel Si and Mn in the cast state and after deformation is established. A significant effect of the total deoxidation in steel on the formation of microhardness inhomogeneity over the cross section of a carbon steel ingot and microinhomogeneity of the structure of individual sections is shown. It was found that after deformation, the central zones turned out to be the most worked out (especially for steel with a chemical composition within the EA1N grade, characterized by an increased content of Mn). Scientific novelty. The study of the influence of fluctuations in the content of the basic elements of carbon steel leads to the development of ideas about the formation of a dendritic structure and segregation heterogeneity in railway axle steels. Рractical value. Knowledge of the principles of segregation formation is necessary to determine further modes of deformation and heat treatment not only for continuously cast billets or ingots, but also for final products.