Micromechanism of cumulative damage in bearing steels under Rolling
Rolling Contact Fatigue (RCF) is harmful and inevitable to bearings and
usually results in the initiation of subsurface damage. This paper
focuses on the cumulative mechanism of subsurface damage in bearing
steels arose from cementite during RCF. The distribution of subsurface
shear stress in bearings was investigated by finite element simulations.
A two-phase atomic model of bcc-Fe and cementite was built. Ten
alternating shear load cycles were applied when the model was initially
in the elastic, elastic-plastic and plastic stages, respectively. The
results show that cyclic softening diversely occurs in all three types
of stress responses, and the progress of plastic accumulation depends on
the amplitude of cyclic load and cycles. Severe shear deformation
eventually leads to the damage of the cementite phase, which might be
the microscopic mechanism of the fatigue failure of bearing steels. The
conclusions presented have general applicability to brittle inclusions
in bearing steels.