Investigating the Process of White Etching Crack Initiation in Bearing Steel

Gould, Benjamin; Greco, Aaron

doi:10.1007/s11249-016-0673-z

Cited by 81 publications

(47 citation statements)

References 38 publications

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“…Furthermore, as can be seen from Figure 6 it can be argued that under boundary lubrication and a roughly constant SRR the run time until failure increases as λ increases. These results are consistent with investigations on a four-disc test rig under boundary lubrication (λ = 0.06-0.7) in which the author suggested that the extent of the WEC damage increases as the lambda value decreases [10].…”

Section: Influence Of Lubrication Regimesupporting

confidence: 90%

“…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%

“…Some authors propose that the cracks are the precursor of the WEA [4,5], while other authors have suggested that the crack initiation and propagations is a consequence of the formation of WEA [6,7]. Besides a local hydrogen ingress [1] other WEC influence factors such as lubricant composition [1,8], sliding conditions [1,9,10], tensile stresses [1,5] and electrical effects [11] had been proposed.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Influence Of Lubrication Regimesupporting

confidence: 90%

Section: Test Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…The proposed initiation and propagation mechanisms for WSF/WECs are: (1) surface initiation through two opposing mechanisms, (1) shear stress-induced fatigue microcracks [17] and (2) localised high circumferential tensile stress spontaneously induced cleavage-like axial cracks that initiate independently [5,17,18], at defects such as inclusions [17][18][19][20][21] or due to corrosion, machining defects or electrical erosion pits [21]; (2) subsurface initiation by non-metallic inclusions (NMIs) [5][6][7][22][23][24][25][26], perhaps in some cases due to tensile stresses [27]; (3) adiabatic shear banding independent or including defects through impact events, cracks forming after microstructural changes occur [2,28]; (4) self-charging of lubricants triggering localised transient current flow causing local electromagnetic induction that crosses the contact surface leading to electrothermal mechanisms triggering subsequent WEA microstructural change [29,30]; (5) a multistage initiation of WECs as a result of migration of carbon under shear stress and high localised energy [31].…”

Section: Introductionmentioning

confidence: 99%

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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“…A number of additives found in lubricants have been shown to promote WSF occurrence, these include; extreme pressure (EP) and anti-wear (AW) additives consisting of sulphur and phosphorus compounds [66,67], where sulphur aids in hydrogen diffusion by preventing atomic hydrogen recombination [68] and formulations of AW zinc dithiophosphates (ZDDP/ZnDTP/ZnDDP) with detergent/rust preventative calcium sulphonate additives [6,61,[69][70][71][72][73][74].…”

Section: Influence Of Oilmentioning

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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Investigating the Process of White Etching Crack Initiation in Bearing Steel

Cited by 81 publications

References 38 publications

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

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

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

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

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