Rolling contact deformation and microstructural changes in high strength bearing steel

This paper examines the connections between the continuing cyclic plastic deformation, the etching effects and the fatigue life of high strength bearing steel under rolling contact. A finite element model is used to calculate the increments of cyclic plastic strain as the roller translates over the running surface. The cyclic plastic strain is related to the plasticity-induced microstructural changes observed in bearings. The calculations are performed for both elastic linear kinematic hardening plastic and elastic-perfectly plastic material behaviors. Observed fatigue lives under rolling contact are compared with the lives obtained in simple cyclic torsion experiments with the same cyclic plastic strain amplitudes. The rotation of the principal shear direction, the smaller strained volume, and the high hydrostatic pressure attending rolling contact may be responsible for the contact lives, which are seven orders of magnitude longer.