Electron microscopy analysis of structural changes within white etching areas

Abstract

In the present work, crack networks with white etching areas (WEAs) in cross-sections of bearings were investigated by a complementary use of SEM and TEM with the focus on the use of orientation contrast imaging and electron backscatter diffraction (EBSD). Orientation contrast imaging was used for the first time to give detailed insight into the microstructure of WEA. A significant difference between Nital-etched and polished WEA samples was observed. It was revealed that WEAs are composed of different areas with varying grain sizes. As a result of secondary transformation, needle-shaped grains were observed within WEAs. Using EBSD analysis, evidence was obtained that WEA formation and accompanying crack growth are without relation microstructural features. In addition, an inhomogeneous chemical structure of WEA as a result of carbide dissolution is revealed by analytical investigations.

Keywords:

• White etching area (WEA)
• White etching cracks (WECs)
• Steel
• Electron microscopy
• Rolling contact fatigue

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Corrigendum

Acknowledgements

The authors thank Leybold Oerlikon for providing the samples and supporting their investigations in the field of white etching areas. Furthermore, the authors are thankful for valuable input by Dr Walter Holweger and appreciated material knowledge provided by Prof. Dr Christoph Broeckmann.

ORCID

A. M. Diederichs http://orcid.org/0000-0002-9751-9575