Effect of hydrogen on butterfly and white etching crack (WEC) formation under rolling contact fatigue (RCF)
Effect of hydrogen on butterfly and white etching crack (WEC) formation under rolling contact fatigue (RCF)
White structure flaking (WSF) as a premature wear failure mode in steel rolling element bearings is caused by white etching cracks (WECs) formed in the 1 mm zone beneath the contact surface. Hydrogen release and diffusion into the bearing steel during operation and transient operating conditions have been suggested as drivers of WSF. The presence of diffusible hydrogen in steel under rolling contact fatigue (RCF) has been shown to strongly promote the formation of WEA/WECs. However, the initiation and propagation mechanisms, as well as the thresholds for WEC formation, are not well understood. This study uses hydrogen charging of 100Cr6 bearing steel rollers prior to testing on a two-roller RCF rig to enable WEA/WEC formation under service realistic loading. This study focuses on the influence of the concentration of diffusible hydrogen, the magnitude of the contact load and the number of rolling cycles on the formation of white etching features (butterflies, WEA/WECs) which are determined by a serial sectioning process. The formation of butterflies was found to be independent of concentration of diffusible hydrogen with the test parameters used, but dependent on contact pressure and number of rolling cycles up to a threshold. WEA/WEC formation thresholds were found at certain values of the concentration of diffusible hydrogen, contact pressure and number of rolling cycles. The results also show evidence for a subsurface initiation mechanism of WECs from non-metallic inclusions. It is proposed that one mechanism of WEC formation is due to multiple linking of extended butterflies or small WECs in the subsurface to form larger WEC networks that eventually propagate to the surface resulting in WSF
rolling contact fatigue, bearings, hydrogen embrittlement, butterfly, white etching cracks (WECs), white structure flaking (WSF)
Evans, M.-H.
5f015c47-3165-4f64-8561-7c047a9d2186
Richardson, A.D.
c801a111-ed18-458e-bce8-450cc499cc74
Wang, L.
c50767b1-7474-4094-9b06-4fe64e9fe362
Wood, R.J.K.
d9523d31-41a8-459a-8831-70e29ffe8a73
Evans, M.-H.
5f015c47-3165-4f64-8561-7c047a9d2186
Richardson, A.D.
c801a111-ed18-458e-bce8-450cc499cc74
Wang, L.
c50767b1-7474-4094-9b06-4fe64e9fe362
Wood, R.J.K.
d9523d31-41a8-459a-8831-70e29ffe8a73
Evans, M.-H., Richardson, A.D., Wang, L. and Wood, R.J.K.
(2013)
Effect of hydrogen on butterfly and white etching crack (WEC) formation under rolling contact fatigue (RCF).
Wear.
(doi:10.1016/j.wear.2013.03.008).
Abstract
White structure flaking (WSF) as a premature wear failure mode in steel rolling element bearings is caused by white etching cracks (WECs) formed in the 1 mm zone beneath the contact surface. Hydrogen release and diffusion into the bearing steel during operation and transient operating conditions have been suggested as drivers of WSF. The presence of diffusible hydrogen in steel under rolling contact fatigue (RCF) has been shown to strongly promote the formation of WEA/WECs. However, the initiation and propagation mechanisms, as well as the thresholds for WEC formation, are not well understood. This study uses hydrogen charging of 100Cr6 bearing steel rollers prior to testing on a two-roller RCF rig to enable WEA/WEC formation under service realistic loading. This study focuses on the influence of the concentration of diffusible hydrogen, the magnitude of the contact load and the number of rolling cycles on the formation of white etching features (butterflies, WEA/WECs) which are determined by a serial sectioning process. The formation of butterflies was found to be independent of concentration of diffusible hydrogen with the test parameters used, but dependent on contact pressure and number of rolling cycles up to a threshold. WEA/WEC formation thresholds were found at certain values of the concentration of diffusible hydrogen, contact pressure and number of rolling cycles. The results also show evidence for a subsurface initiation mechanism of WECs from non-metallic inclusions. It is proposed that one mechanism of WEC formation is due to multiple linking of extended butterflies or small WECs in the subsurface to form larger WEC networks that eventually propagate to the surface resulting in WSF
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e-pub ahead of print date: 14 March 2013
Keywords:
rolling contact fatigue, bearings, hydrogen embrittlement, butterfly, white etching cracks (WECs), white structure flaking (WSF)
Organisations:
nCATS Group
Identifiers
Local EPrints ID: 354219
URI: http://eprints.soton.ac.uk/id/eprint/354219
ISSN: 0043-1648
PURE UUID: 1557c644-fc19-4d51-95f5-38b0e7a9272e
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Date deposited: 08 Jul 2013 13:38
Last modified: 15 Mar 2024 03:12
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Author:
M.-H. Evans
Author:
A.D. Richardson
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