WEC Formation in Rolling Bearings under Mixed Friction: Influences and “Friction Energy Accumulation” as Indicator

Kruhöffer, Wolfram; Loos, Jörg

doi:10.1080/10402004.2016.1183250

Cited by 37 publications

(37 citation statements)

References 16 publications

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“…These areas have also been found to coincide with zones of highest concentrations of hydrogen [50,59,60]. Supporting evidence for the slip energy criterion has been shown on FAG-FE8 tests where WECs appeared firstly at areas of high frictional energy, this also being demonstrated in tests using angular contact ball bearings [29,58]. A number of inclusion-WEC interactions were also recorded during fine serial sectioning corresponding to the 2-3-mm zone of high slip energy dissipation and asperity accumulation (see Fig.…”

Section: Wec Initiation and Evolutionmentioning

confidence: 48%

“…It is noted that the asperity friction energy accumulation is greater in the washers than the rollers, where energy dissipation is greater in the inner raceway than the outer (see Fig. 6, [58]). This is contradictory to the result seen in this study, this discrepancy not being understood.…”

Section: Wec Initiation and Evolutionmentioning

confidence: 99%

“…These zones correspond to areas of high slip energy (PVmax, the product of contact pressure P and slip velocity V, MPa ms −1 , see Fig. 12), slip energy taking into account asperity contact (P c V value which takes into account the asperity contact pressure P c ) and asperity friction accumulation e a,c max which relates the regeneration time span between consecutive contact load cycles on tested WEC lives and the specific frictional energy input into the a surface during the contact load cycle [58]. Slip energy criteria have been linked to WSF, WSF occurring at areas of greatest PVmax.…”

Section: Wec Initiation and Evolutionmentioning

confidence: 99%

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The Evolution of White Etching Cracks (WECs) in Rolling Contact Fatigue-Tested 100Cr6 Steel

et al. 2017

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The formation of white etching cracks (WECs) in steel rolling element bearings can lead to the premature rolling contact fatigue (RCF) failure mode called white structure flaking. Driving mechanisms are still debated but are proposed to be combinations of mechanical, tribochemical and electrical effects. A number of studies have been conducted to record and map WECs in RCF-tested samples and bearings failed from the field. For the first time, this study uses serial sectioning metallography techniques on non-hydrogen charged test samples over a range of test durations to capture the evolution of WEC formation from their initiation to final flaking. Clear evidence for subsurface initiation at non-metallic inclusions was observed at the early stages of WEC formation, and with increasing test duration the propagation of these cracks from the subsurface region to the contact surface eventually causing flaking. In addition, an increase in the amount of associated microstructural changes adjacent to the cracks is observed, this being indicative of the crack being a prerequisite of the microstructural alteration.

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Section: Wec Initiation and Evolutionmentioning

confidence: 48%

Section: Wec Initiation and Evolutionmentioning

confidence: 99%

Section: Wec Initiation and Evolutionmentioning

confidence: 99%

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The Evolution of White Etching Cracks (WECs) in Rolling Contact Fatigue-Tested 100Cr6 Steel

et al. 2017

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“…Two different test series were defined on the basis of previous investigations on two-and fourdisc test rigs [7,9,10,18]. Whereas for the first test series λ-values > 3 were chosen, the second test series was conducted under boundary lubrication (λ < 1).…”

Section: Test Methodsmentioning

confidence: 99%

Influence of Slip and Lubrication Regime on the Formation of White Etching Cracks on a Two-Disc Test Rig

et al. 2018

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A common cause for maintenance and downtime in multiple fields of the mechanical transmission industries are premature rolling bearing failures due to white etching cracks (WEC). Within this work, WEC have been successfully recreated on a two-disc test rig under rolling contact loading without additional loading such as hydrogen pre-charging. This paper summarizes the state of the investigations regarding the influence of the slip type and the lubrication regime on the WEC formation on the two-disc test rig.

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“…This suggests that the combination of slip/frictional energy input into the system and diffusion of hydrogen during operation may influence the propensity for WEC formations. Hydrogen diffusion analysis through finite element simulations attempts to link asperity friction energy with the absorption of hydrogen to explain the vulnerability of bearings to WEC formations in FE8 tested cylindrical roller thrust bearings [58]. Simulations show higher hydrogen concentrations in areas of high slip energy and asperity friction accumulation.…”

Section: Rcf Testingmentioning

confidence: 99%

Thermal Desorption Analysis of Hydrogen in Non-hydrogen-Charged Rolling Contact Fatigue-Tested 100Cr6 Steel

et al. 2017

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Hydrogen diffusion during rolling contact fatigue (RCF) is considered a potential root cause or accelerator of white etching cracks (WECs) in wind turbine gearbox bearing steels. Hydrogen entry into the bearing steel during operation is thought to occur either through the contact surface itself or through cracks that breach the contact surface, in both cases by the decomposition of lubricant through catalytic reactions and/or tribochemical reactions of water. Thermal desorption analysis (TDA) using two experimental set-ups has been used to measure the hydrogen concentration in non-hydrogen-charged bearings over increasing RCF test durations for the first time. TDA on both instruments revealed that hydrogen diffused into the rolling elements, increasing concentrations being measured for longer test durations, with numerous WECs having formed. On the other hand, across all test durations, negligible concentrations of hydrogen were measured in the raceways, and correspondingly no WECs formed. Evidence for a relationship between hydrogen concentration and either the formation or the acceleration of WECs is shown in the rollers, as WECs increased in number and severity with increasing test duration. It is assumed that hydrogen diffusion occurred at wear-induced nascent surfaces or areas of heterogeneous/patchy tribofilm, since most WECs did not breach the contact surface, and those that did only had very small crack volumes for entry of lubricant to have occurred.

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WEC Formation in Rolling Bearings under Mixed Friction: Influences and “Friction Energy Accumulation” as Indicator

Cited by 37 publications

References 16 publications

The Evolution of White Etching Cracks (WECs) in Rolling Contact Fatigue-Tested 100Cr6 Steel

The Evolution of White Etching Cracks (WECs) in Rolling Contact Fatigue-Tested 100Cr6 Steel

Influence of Slip and Lubrication Regime on the Formation of White Etching Cracks on a Two-Disc Test Rig

Thermal Desorption Analysis of Hydrogen in Non-hydrogen-Charged Rolling Contact Fatigue-Tested 100Cr6 Steel

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