The microstructure of a damaged bearing from the field was characterized in this work with the intention to better understand microstructural features behind formation of White Etching Cracks (WEC) in bearings. Microstructural characterization of the altered white etching area (WEA) involved conventional electron backscattered diffraction (EBSD), followed by transmission electron microscopy (TEM), and transmission Kikuchi diffraction (TKD). In addition, automated crystallographic orientation mapping in TEM was performed on lamellae from selected regions of the WEA extracted via focus ion beam milling. The results revealed that the orientation of detectable grains within WEA is similar to that of the vicinal bulk material. WEA consists of small spherical grains (average 30 nm) and the orientation of the grains varied significantly in the deformed zone, suggesting that recrystallization had occurred. The interface between bulk material and the deformed zone is very sharp. Furthermore, needle-like grains, most likely originating from the zone undergoing only modest levels of severe plastic deformation, occurred in WEA. The occurrence of different grain sizes in WEA and incomplete plastic deformation strongly support the hypothesis of WEC formation via severe plastic deformation followed by recrystallization. ... Read more

Automated mapping of crystallographic orientations based on the diffraction of electrons has been widely employed to characterize the microstructure of crystalline materials. The most commonly used technique in this field is Electron Backscatter Diffraction (EBSD), which is a scanning electron microscopy based technique. Modern EBSD owes its popularity to the fact that it offers a reasonable balance between spatial resolution (30–50 nm) and field width (~mm2). This article highlights a number of new developments and applications of orientation contrast microscopy including (1) 3D-EBSD, (2) Transmission Kikuchi Diffraction (TKD) and (3) ACOM-TEM (Automatic Crystal Orientation Mapping in the TEM) ... Read more