Optimal Mn/Si parameters for adjusting the mechanical properties of steel for railway axles

Abstract

The work presented a comprehensive approach to finding the optimal steel composition within known grades based on the concept of directional chemical bonding. This approach made it possible to take into account the overall chemical composition and to analyze the na-ture of interactions between elements at the level of interatomic bonds, which is critical for predicting the properties of the final material. The concept of directed chemical bonding was based on the idea of the ability of individual elements to undergo electronic redistribution in the melt, which in turn affects the structure and stability of the system. The aim of the study was to determine the effect of variations in the content of the main matrix elements — carbon, silicon, and manganese - on the charge state of the system, represented by the generalized parameter ZY. This parameter reflects the degree of chemical balance in the alloy and serves as an indicator of the stability of the melt’s electronic structure. As a result, the sensitivity of the system to the Mn/Si ratio was investigated as an indicator defining electronic and struc-tural equilibrium. Thus, to enhance the ZY parameter, whose increase leads to improved hardness, it is necessary to prioritize manganese content after the Mn/Si ratio reaches 2.8–3.2, while below this interval — through an increase in silicon content. The manganese-to-silicon ratio (Mn/Si) should be within the range of 2.8–3.2. An increase in Mn/Si beyond 3.2 causes manganese to dominate, which may disrupt the balance. Therefore, controlling the content of alloying elements, especially silicon and manganese, is a key condition for produc-ing steels with predictable properties. The results of the modeling emphasize the feasibility of using computational approaches in materials science. Predictive modeling allows for the ef-fective adaptation of steel structure to the specified performance characteristics already at the stage of chemical composition design. This contributes to reducing experimental devel-opment costs and shortening the time to bring new alloys into production.