Investigation of influence of white layer geometry on spalling property in railway wheel steel

Spalling is rolling contact fatigue (RCF) damages of railway wheels, as a result of unexpected wheel slides on a rail. The major characteristic in spalling is that fatigue cracks initiate from white layers. In this study, in order to evaluate the influence of the white layer geometries on spalling properties, RCF tests and elasto-plastic FEM analyses were carried out. Moreover, the Dang Van model, which is the multiaxial fatigue strength evaluation methods, was applied to predict the crack initiations in RCF tests. There are three main results from this study. Firstly, RCF tests yielded that the crack initiations were less in the smaller white layers than in the larger ones. In addition, the crack initiations of the matrices were less than those of the white layers. Secondly, FEM analysis results showed that the maximum stresses were lower in the smaller white layers than in the larger ones. This result corresponded to the crack initiation behaviours of RCF tests. Finally, the fatigue strength prediction results by the Dang Van model were reasonably equivalent to the RCF test results. Therefore, it was concluded that the crack initiations in spalling could be reduced by the smaller white layer.

Research highlights▶ The white layer geometry influences spalling properties of the railway wheel steel. ▶ More cracks initiated in the test specimens with the larger white layers. ▶ The fatigue strengths predicted by the Dang Van model correspond to the test results.