Investigation on rolling contact fatigue of railway wheel steel with surface defect

Abstract In this study, the effect of surface defect on the rolling contact fatigue (RCF) of railway wheel steel was investigated. Artificial defects with different dimensions were produced on unprerolled and prerolled wheel discs to simulate defects appearing in actual wheels. Subsequently, twin-disc tests were conducted under the typical contact stress and slip ratio. Finally, a novel method was used to investigate the RCF crack initiation of the wheel disc. Results show that the prerolling promotes RCF crack initiation for wheel steels with surface defects. The critical defect dimension resulting in the RCF crack initiation of the prerolled wheel disc is 100–200 μm. Considering the scaling factor between the actual wheel and test wheel disc, the predicted critical defect dimension is 2–4 mm for the actual wheel, which agrees with field observations. For the prerolled wheel steel, RCF cracks initiate from the region near the middle edge of the defect, where the most significant stress concentration appears. An increase in defect dimension increases the stress concentration, thereby reducing the RCF life. The Fatemi–Socie multiaxial fatigue parameter in conjunction with the theory of critical distances can predict the effect of defect dimension on variation in RCF life.