On the relationship between the steel mechanical properties and optimal remanufacturing process of bearings

Surface indentations of bearing raceway, caused by contamination particles, are a major source of surface-initiated rolling contact fatigue in heavy-industry applications. Material pile-up (shoulders) formed around the indent are the primary contributors to local pressure increase, lubricant film disruption, tensile residual stresses, crack initiation, and ultimately spalling. This study provides theoretical and experimental support for a remanufacturing approach in which the indentation shoulders are removed by using the carefully designed remanufacturing process. Finite Element simulations are used to assess the effect of shoulder removal on contact pressure redistribution and residual stress relaxation. The results show that removing the shoulders reduces the local contact pressure and mitigates tensile residual stresses around the indent. Rolling contact fatigue tests on cylindrical roller bearings further demonstrate that indented bearings exhibit significantly reduced life, whereas remanufactured bearings recover life equivalent to that of new bearings. The study also addresses the optimization of remanufacturing depth by linking shoulder formation to the plastic response of bearing steels. Since hardness alone is insufficient to predict shoulder build-up, a hybrid material characterization method is applied, combining nanoindentation testing with screw dislocation strengthening theory to determine the stress-strain response of hardened bearing steels. This approach is particularly relevant for surface-hardened components, where conventional mechanical testing is impractical. The results provide scientific justification for a targeted, energy-efficient remanufacturing process that can extend bearing service life by using carefully designed remanufacturing process as a function of steels mechanical properties.