Rolling Contact Fatigue: Experimental Study of the Influence of Sliding, Load, and Material Properties on the Resistance to Micropitting of Steel Discs

Abstract

An experimental study was carried out on a twin-disc machine to study the influence of various parameters on the resistance to micropitting of steel discs. The slide-to-roll ratio (SRR = sliding speed/mean rolling speed) was shown to have a great influence on surface-initiated pitting, which occurs even for low sliding speeds. Metallographic studies revealed the disadvantages of atmospheric pressure heat treatments compared to low-pressure ones: discontinuities such as oxides under the surface favor crack propagation. The load applied on the discs—and thus the contact pressure—did not affect the micropitting of the surfaces in the range studied. The effects of surface machining and surface treatments were finally considered: ground surfaces showed better resistance to micropitting than surfaces obtained by turning, and the benefits of shot peening were exposed. The influence of surface roughness and material properties on the resistance to pitting is discussed in the light of these results.

KEY WORDS:

• Rolling Contact Fatigue (RCF)
• Micropitting
• Heat Treatments
• Surface Treatments
• Shot Peening
• Material Properties
• Twin-Disc Machine

ACKNOWLEDGEMENTS

The authors thank Mathilde Meheux from the Ascometal Research Centre, CREAS, for providing the different types of steel tested throughout this study and for her scientific contribution. We are also grateful to ECM France, based in Grenoble, for carrying out the low-pressure heat treatments on the different test discs.

Review led by Guillermo Morales Espejel