Phase changes in fatigued ball bearings

Substantial structural changes may occur in ball bearings during high stress contact fatigue. The phenomenon is frequently reported in the literature. Unfortunately, different authors have used different terminologies for identifying the various structural features observed. In addition, most investigators have restricted their methods to light optical metallographic techniques. This has caused considerable disagreement in interpreting the resulting structures. The purpose of the present work has been to contribute to the classification of the structural changes in fatigued ball bearings by the use of a combined light and electron microscope technique, which has earlier been successfully applied to simple, well-known steel structures. It proved possible to distinguish a number of well-defined structural features and to propose an improved nomenclature compared to earlier literature reports.