Subsurface Crack Propagation from Internal Defect in Rolling Contact Fatigue of Railway Wheel Steel

Abstract

A rolling contact fatigue failure is one of the main fatigue damages in railway wheels due to cyclic rolling contact with rails. This fatigue failure caused by internal defects such as nonmetallic inclusions or voids might occur in heavy haul freight car wheels. Subsurface crack propagation behaviors from the internal defects are evaluated by twin disc type rolling contact fatigue tests using test specimens with artificial defects and by finite element analyses simulating the rolling contact fatigue tests. The subsurface cracks are more likely to propagate in the test specimens with larger artificial defects. In addition, the cracks initiating from the trailing side of defects propagate faster than those from the leading side. Shear mode equivalent stress intensity factors obtained from the finite element analyses correspond well to the results of rolling contact fatigue tests. The test specimen models with larger defect have larger equivalent stress intensity factor ranges than the test specimen model with smaller defect in both leading and trailing side. The results of finite element analyses also suggest that the crack propagations are affected by the deformation of artificial defects and this leads to have higher resistance to crack propagation in the test specimens with smaller internal defects.