Study on wear and RCF performance of repaired damage railway wheels: Assessing laser cladding to repair local defects on wheels

Sometimes, railway wheels cannot be re-turned and have to be discarded far before its time in service due to local defects and severe wear. Laser cladding which deposits a surface layer of a repair material may be an approach to repair wheels locally. In this study, cladding materials are deposited at a small section of wheel surfaces in order to repair wheels with local defects. 316L, 410, and 420 stainless steel were used as cladding materials on wheel discs while rail discs are unclad. Twin-disc tests were performed to study wear and rolling contact fatigue (RCF) behaviours of clad wheels. Results indicate that adhesion coefficients do not have notable difference between clad and unclad discs. All three clad wheel discs have slightly lower wear rates compared to the unclad wheel discs. The wear rates decrease with increased hardness of the clad materials. Plastic deformation and ratcheting is found on the surface of unclad samples/zones. Only small surface cracks can be found. Deep cracks are found at the boundary between clad and unclad zones leading to a large chunk of material loss. The cracks may be initiated from where maximum shear stress presents below the surface and further propagate along the boundary due to the difference in deformation between clad and unclad materials.