Rolling bearing applications: Some trends in materials and heat treatments

Rolling contact fatigue resistance and dimensional stability are the two important requirements for rolling bearing materials. Rolling contact fatigue can be initiated under the surface due to the presence of elastic inhomogeneities (inclusions) in the material, and, on the surface due to starved or contamination lubrication conditions. Two classical solutions in terms of material or heat treatment are presented and criticised. First, it is shown that ceramic balls, classically used to reduce contact stress, may induce deeper dents under contaminated environment. Second, an integrated approach based on thermoelectric power measurement is used to predict and understand the dimensional stability of bainitic 100Cr6 steel that exhibits dimension change proportional to its retained austenite content.