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@PHDTHESIS{Steinweg:995123,
author = {Steinweg, Florian},
othercontributors = {Broeckmann, Christoph and Mayer, Joachim},
title = {{W}hite etching areas und white etching cracks in 100{C}r6
und {X}30{C}r{M}o{N}15-1},
volume = {30},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Düren},
publisher = {Shaker Verlag},
reportid = {RWTH-2024-09728},
isbn = {978-3-8440-9614-9},
series = {Werkstoffanwendungen im Maschinenbau},
pages = {1 Online-Ressource : Illustrationen},
year = {2024},
note = {Druckausgabe: 2024. - Auch veröffentlicht auf dem
Publikationsserver der RWTH Aachen University; Dissertation,
RWTH Aachen University, 2024},
abstract = {The formation mechanisms of white etching areas (WEA) and
white etching cracks (WEC) are only partially understood.
Furthermore, no single factor seems solely responsible for
WEA/WEC. Therefore, the aim of this work was to investigate
the underlying mechanisms that lead to WEA/WEC. To achieve
the intended objective, an assessment of the following
influencing factors was carried out: contact parameters,
lubricant formulation, electrical current flow, and
diffusible hydrogen. The basis for this investigation were
four-disc test-rig experiments with specimens made of 100Cr6
and X30CrMoN15-1. In addition, metallographic and X-ray
diffraction analyses were performed. The investigations
showed that a sufficient concentration of, previously
artificially introduced, atomic hydrogen in 100Cr6 leads to
WEA/WEC when subjected to rolling contact stresses. The
contact parameters Hertzian pressure and slip influence the
damage pattern but not the formation of WEA/WEC. An
electrical current flow is also sufficient to generate
WEA/WEC damage under rolling contact stresses, even without
hydrogen pre-charging of the specimens. The current flow
direction influences the contact cycles and the reaction
layers, with anodic specimens tending to fail earlier.
Additional slip also leads to an earlier WEA/WEC failure. It
was shown that a lubricant containing zinc
dialkyldithiophosphate and over-based calcium sulfonate can
cause WEA/WEC under boundary lubrication conditions, while a
barium-containing lubricant causes classic rolling contact
fatigue damage. The results suggest that atomic hydrogen
plays a minor role under the tribological contact conditions
and that unprotected metal surfaces in contact are critical
for WEA/WEC formation. The WEA/WEC networks and the WEA
volume increase with increasing test duration. Initially,
local WEA/WEC develop in the form of a substructure, which
interconnect over time to form large-scale WEA/WEC networks.
The first WEA formation is attributed to a local deformation
process in which the (Fe, Cr)3C carbides decompose. For the
first time, the formation of WEA was experimentally verified
in test specimens made of X30CrMoN15-1 artificially loaded
with hydrogen. These WEA consist of nanoferritic grains and
resemble the nanocrystalline WEA in 100Cr6. However, in
contrast to the (Fe, Cr)3C carbides in 100Cr6, the M2(C, N)
and M23C6 precipitates in X30CrMoN15-1 do not entirely
decompose during WEA formation and undergo a plastic
deformation process within the WEA.},
cin = {418110},
ddc = {620},
cid = {$I:(DE-82)418110_20140620$},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
doi = {10.18154/RWTH-2024-09728},
url = {https://publications.rwth-aachen.de/record/995123},
}
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