Spherical Particles formed in Rolling Contact Fatigue

Abstract

IN an investigation of fracture phenomena associated with rolling contact fatigue failure¹, it was suggested that spherical particles found on fractured bearing ball surfaces could be formed from tongues of metal removed by a cavitation erosion process due to the application and release of extreme pressure in the lubricant entrapped in the propagating crack by rolling contact. A correlation between cavitation erosion and rolling contact fatigue resistance has been established². Loose pieces of metal could be severely worked by the pressure build-up in the lubricant entrapped in the fatigue crack or by pressure on the fracture faces during passage of the crack over the mating bearing surface. The mechanism of formation of the spherical particles and the possibility of their being artefacts^3,4 are uncertain. It has been reported⁵ that similar spherical particles of debris are formed under specific conditions of fretting, and their formation by a process of deformation has been provided by scanning electron microscopy.