X-Ray Diffraction Analysis of Structural Changes Induced by Overrolling

Abstract

A new method of X-ray diffraction analysis to evaluate structural changes in rolling ele - ment bearing components is demonstrated. The basics of residual stress measurement by X-ray diffraction based on the sin 2 ψ method are explained. Microstructural analysis is performed on bearing components after rig testing and after use in field. The results shown in this chapter are mostly derived from rolling element bearing applications in aero engines. First it is shown how an estimation of a rolling contact fatigue life can be derived from microstructural analysis. Second it will be shown that surface near induced residual stresses can improve rolling contact fatigue life. Finally it will be demonstrated that basic results from rig testing can be transferred to use in field. microstructural analysis. A comparison of microstructural evaluation results on components taken from engine bearings after use in the field with results from parts after rig testing shows, that basic causes and effects are similar in both cases. These results therefore provide a confirmation that results from rig testing can be used for bearing design also in demanding applications.