SYMPOSIA PAPER Published: 08 September 2020

Complexity of Dimensional Stability of Case-Hardened Bearing Components


The thermal effect is the most considered parameter affecting the dimensional stability of a bearing component. It is generally associated with the transformations of the metastable phases in the steel upon exposure to the operating temperature over a long period of time in service. In reality, the dimensional change of the bearing components is thermomechanically activated given that the experienced hoop stress caused by interference fit promotes the dimensional change considerably due to stress relaxation. The phenomenon becomes more complex for case-hardened bearings because the thermomechanical responses of the case and core are different, and the dimensional change is a result of the combined contribution from the case and core. Our previous studies did show the decrease of dimensional stability with the increase of retained austenite content in the case, the case depth, and the interference fit applied during the application. It is challenging, however, to obtain consistent data on microstructural changes accounting for dimensional change possibly because of the inhomogeneity of the microstructure. The current approach is to carry out ring-on-shaft thermal exposure tests complimented with state-of-the-art dilatometry work on the case and core microstructures. This work enables us to assess the dimensional stability of the case-hardened bearing components. The results can then be used to suggest an improved test method and give input to future model development and prediction on dimensional stability of case-hardened bearing components.

Author Information

Yan, Pei
SKF Research and Technology Development, NL
Sherif, Mohamed, Y.
SKF Research and Technology Development, NL
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Pages: 246–260
DOI: 10.1520/STP162320190076
ISBN-EB: 978-0-8031-7693-5
ISBN-13: 978-0-8031-7692-8