SYMPOSIA PAPER Published: 11 December 2017

Influence of Material and Heat Treatment on the Formation of WECs on Test Rig FE8


White etching cracks (WECs), or white structure flaking, is a failure phenomenon that has been reported as emerging in rolling bearing parts for more than the past two decades. This failure mode appears only if, in addition to the normal Hertzian load, a so-called additional load is applied. WECs can occur regardless of the bearing type and size and in both oil- and grease-lubricated bearings. By modifying the testing conditions of an FE8 type test rig, it is possible to alter the failure mechanism from classical wear failures to WEC formations. This allows for easy, fast, and reproducible testing of materials and heat treatment variants to check their WEC formation propensity. This paper explains the methodology of testing on a FE8 test rig, the subsequent failure analysis, and the testing results. The tested components are produced from a wide range of commonly used bearing materials that in these tests are through hardened variants of low and high alloyed steels, case carburized steel with high retained austenite content, and inductive hardened quenched and tempered steel. In addition to the spread in the base materials with different contents of carbon and alloying elements, the variations in materials and heat treatments offer the possibility of significantly varying the content of retained austenite and the residual stress distribution. The results show that all the tested low alloyed materials fail with the WEC mechanism, whereas a significant increase in lifetime can be observed in terms of inductive hardened quenched and tempered steel. Only the nitrogen alloyed stainless steel Cronidur 30 demonstrates an outstanding performance without WEC formation.

Author Information

Blass, Toni
Schaeffler Technologies AG & Co. KG, Schweinfurt, DE
Trojahn, Werner
Schaeffler Technologies AG & Co. KG, Schweinfurt, DE
Merk, Daniel
Schaeffler Technologies AG & Co. KG, Schweinfurt, DE
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Developed by Committee: A01
Pages: 129–150
DOI: 10.1520/STP160020160139
ISBN-EB: 978-0-8031-7644-7
ISBN-13: 978-0-8031-7643-0