Study on fatigue failure mechanism at various temperatures of a high-speed railway wheel steel

The fatigue life and limit of the wheel rim and the wheel web position of a high-speed railway wheel steel at various testing temperatures (−60 to 60 °C) were investigated. Both microstructures and fracture morphologies were observed in details. The fatigue failure mechanism at various temperatures was discussed. The results demonstrated that the wheel rim had a longer fatigue lifetime and a higher value of fatigue limit than the corresponding properties of the wheel web due to various microstructural distributions. The temperature, microstructure and stress amplitude had a significant impact on the fatigue initiation and propagation. The typical features including the propagation zone of regular fan-like shapes, the fatigue step, the gray wear facets and the fatigue striation were observed on the fracture surface, which were related to the failure mechanism transition.