Аналіз відповідності дослідних сталей для залізничних рейок сучасним стандартам України та ЄС

Abstract

The process of operating vehicles determines the interaction of the wheel and rail. Traffic safety and the main technical and economic indicators of track management and rolling stock largely depend on these parameters. The result of this interaction are changes in the metal, which arise from rolling friction and especially from the friction of the wheel sliding on the rail during braking, due to these changes, the wheels of the rolling stock wear out. The purpose od the work is to research of the microstructure and mechanical properties of steels of promising chemical compositions to meet modern requirements for railway rails. Methods of metallographic analysis, determination of mechanical properties, and chemical analysis were used. Samples made from laboratory melts of steels with a promising chemical composition served as material for detailed microstructure studies. When comparing prospective chemical compositions, it was established that steel 1 meets the requirements of DSTU EN 13674:2018 for basic chemical elements and has differences according to DSTU 4344:2004, namely: increased carbon content. When comparing the experimental chemical composition of steel 2, it was found that this steel does not meet the requirements of DSTU EN 13674:2018 and DSTU 4344:2004, namely: a reduced amount of carbon and an increased content of silicon, chromium and molybdenum. According to the results of the analysis of the values of mechanical properties, it was established that steel 1 and 2 meets the requirements of DSTU EN 13674:2018. Steel 1 does not meet the requirements of DSTU 4344:2004 in terms of yield strength and relative narrowing, and steel 2 does not meet the requirements of DSTU 4344:2004 for the highest category of rails in terms of temporary resistance values. Based on the results of the microstructure studies, it was established that the test steel 1 after heat treatment has a structure of highly dispersed pearlite with a small amount of coarse-plate pearlite. When analyzing the microstructure of steel with a promising chemical composition 2, it was established that the structure consists of carbide-free bainite.