Surface cracks initiation on carbon steel railway wheels under concurrent load of continuous rolling contact and cyclic frictional heat

Focusing on the durability of carbon steel railway wheels, so-called tread thermal cracks, one of severe damages on the tread surface, were investigated to understand the cracks generation processes involving initiation and propagation. We have demonstrated that tread thermal cracks can be experimentally reproduced under the condition of concurrent loading of continuous rolling contact with rails and cyclic frictional heat from brake blocks, through the experiments using an actual railway wheel. Relations of residual stress, cracks configuration and fracture surface were examined to consider the crack generation process. Plastic deformation and thermal stress near the surface result in substantial tensile residual stress, which causes the generation of cracks.