Monotonic and cyclic deformation of a high silicon pearlitic wheel steel

The development of railway wheel steel grades has gone towards higher strength to enhance rolling contact fatigue resistance and ability to withstand thermally induced damage throughout the service lifetime. In this study a recently developed wheel steel material for passenger trains containing high levels of manganese and silicon, approximately 1 wt% of each, was tested in low cycle fatigue at different total strain amplitudes. In addition, monotonic tensile and Charpy V-notch impact testings in the temperature range −60 °C to 180 °C were performed. The results were compared to another steel grade commonly used in Europe for railway wheels. The low cycle fatigue results show similar cyclic lifetime Nf, and fatigue stress amplitude development for both materials, but the highly alloyed steel exhibits reduced cyclic softening and hardening during the fatigue life and is in this respect more stable in its behaviour. As is typical for pearlitic–ferritic steels both materials show a pronounced monotonic strain hardening. It was concluded that the increased levels of manganese and silicon have minor effects on monotonic behaviour but substantial influence on cyclic behaviour at ambient temperatures. At increased temperatures, though, there are indications of additional effects on monotonic behaviour. However, the high temperature properties have to be investigated further to gain full understanding of mechanisms and effects.

Research highlights▶ High silicon–manganese alloyed wheel steels show superior cyclic behaviour. ▶ Addition of silicon and manganese enhance high temperature mechanical properties. ▶ Monotonic and cyclic stress depend upon initial hardness of the wheel material.