S45C鋼のころがり疲労試験における表面損傷

抄録

In order to clarify the behavior of pitting damage, the rolling contact fatigue tests were performed under the pure rolling and the sliding-rolling contact conditions on the annealed S45C roller specimens, and especially the surface and the cross section of roller specimens during the rolling contact fatigue tests were observed with microscopes. The summarized results are as follows:
(1) The pits develop along the forward flow formed in the subsurface layer of roller under both the pure rolling and the sliding-rolling contact conditions, and the shapes of pits are on the whole irregular in the pure rolled specimens but are fan-shaped in the sliding-rolled specimens. No subsurface origin cracks are observed in both contact conditions.
(2) The damages, such as the scratching or adhesive wears, the micro-pits caused by the repetitions of the normal and tangential stresses and so on, appear on the roller surface before the formation of pits. They are observed mainly in ferrite grains. And the dislocation microstructures of the roller surface exhibit distinct substructures at the formation of pitting cracks.