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 degrees 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.