A fundamental study on the impact of surface integrity by hard turning on rolling contact fatigue

Hard turning has the potential to produce favorable surface integrity that would improve component life in rolling contact. However, the effects of the process-induced residual stress profile and the white layer on rolling contact fatigue (RCF) are poorly understood. This study aims to answer the long-standing question of how residual stress and the white layer affect RCF. Based on the developed real-time RCF testing system, a series of RCF tests were conducted for hard turned AISI 52100 steel components. The test results have shown that the acoustic emission amplitude is most consistent and sensitive to fatigue damage than other AE parameters. A white layer induced by hard turning is very detrimental to RCF. A component free of a white layer can have a life six times that of a white layer component. As the white layer increases in thickness, the fatigue life decreases. Surface residual stresses and near-surface residual stress profiles are significant factors for RCF, while the depth of maximum compressive residual stress in subsurface is not critical. Surface integrity affects RCF through the mechanism of near surface damage rather than subsurface damage.