Investigation of Structural Changes through Overrolling by X-Ray Diffraction Methods

Rolling element bearings undergo high dynamic loading in the region of the contact areas. If the stress level caused by the contact of the curved bodies exceeds a material specific limit, material fatigue can occur which limits the lifetime of a bearing. By defined induced residual stresses in the surface near region the lifetime of bearings can be increased considerably. In order to get data, rig tests were performed at FAG with bearing components made from the high speed steel M50. Besides a statistical evaluation of the test results investigation of the tested bearing parts by metallografic inspection methods and by X-ray diffraction analysis has been performed. The sensitivity in detection of structural changes by X-ray methods is high, therefore an assessment of the effectivity of induced residual stresses is possible after a comparatively short time rig testing.