Formation mechanism of brown etching layers in pearlitic rail steel

Tung, Po‐Yen; Zhou, Xuyang; Morsdorf, Lutz; Herbig, Michael

doi:10.1016/j.mtla.2022.101625

Cited by 10 publications

(4 citation statements)

References 57 publications

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“…Recently, so-called "Stratified Surface Layers" (SSLs)observed on wheels in servicedevote growing research interest due to its predicted relation to fatigue crack initiation. [1][2][3][4][5][6][7] Such near-surface microstructures are a combination of a white etching layer (WEL) and an underlying brown etching layer (BEL). The term WEL as a feature in wheel-rail contacts was first mentioned around 1950, [8][9][10][11] and originating from the resistance to etching in contrast to the bulk material, revealing a featureless white appearance under light optical microscopes (LOMs).…”

Section: Introductionmentioning

confidence: 99%

“…Research on BEL is relatively new and there is no consensus on its formation yet. 1,[3][4][5][6]18 The vast variety of SSLs observed on rails and wheels seems to be an insurmountable obstacle for a systematic study of the formation mechanism and its influencing parameters, since the loading history of samples from field is never fully clear. This demands a reproducible approach to create defined SSLs.…”

Section: Introductionmentioning

confidence: 99%

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Influence of thermal loading parameters and microstructure on the formation of stratified surface layers on railway wheels

Freisinger,

Pichelbauer,

Trummer

et al. 2024

Proceedings of the Institution of Mechanical Engineers, Part F:

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Due to an increasing trend towards environmentally friendly public transport, rail networks face higher speeds and wheel loads affecting the material degradation of the railway components. Within this study, influencing parameters on the formation of stratified surface layers, forming on railway wheels during service due to thermal loadings in the wheel-rail contact, are studied. These layers consist of white etching layer and underlying brown etching layer and are susceptible to fatigue crack initiation. By using laser surface treatments, its formation based on two consecutive thermal loadings is systematically demonstrated on ER7 wheel steel. Further, a decrease in layer thickness with decreasing laser power, and an increase in brown etching layer thickness with increasing laser power difference is shown. Moreover, the effect of finer grain size leading to an increased layer thickness, and the influence of the chemical composition by comparing the standard ER7 wheel steel to a micro-alloyed wheel steel are demonstrated.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of thermal loading parameters and microstructure on the formation of stratified surface layers on railway wheels

Freisinger,

Pichelbauer,

Trummer

et al. 2024

Proceedings of the Institution of Mechanical Engineers, Part F:

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“…This has made it possible to analyze the mechanisms of wear, the degradation of rail properties and the reasons for their failure. The formed data bank, as well as the results of recent studies [14][15][16][17][18][19] of the patterns of structure formation, phase composition and dislocation substructure can be considered as achievements in the physics of hypoeutectoid pearlite steels. New steel grades have been sought for several years in order to limit contact fatigue and wear.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Cementite Substructure of Rails from Hypereutectoid Steel during Operation

Gromov,

Ivanov,

Porfiriev

et al. 2023

Metals

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Transmission electron microscopy methods were used to analyze the cementite substructure in the head of special-purpose long rails of the DT400IK category, made of hypereutectoid steel, after long-term operation on an experimental track on the Russian Railways ring (the tonnage was 187 million tons). It is noted that the study of various aspects of cementite—its structure, morphology, chemical composition, crystal lattice defects—is relevant. The steel structure is represented by three morphological components at a distance of 10 mm from the sample surface: lamellar perlite, fractured and fragmented perlite. The volume fraction of lamellar perlite in the material is 65%. It is shown that after operation, the cementite plates are bent and separated by ferrite bridges. In the plates of ferrite and cementite, a dislocation substructure is formed, which is of a chaotically distributed and network type in ferrite and of an ordered type in cementite. An increased density of dislocations at the ferrite–cementite interfaces compared to the volume of ferrite plates was noted. Two possible mechanisms of deformation transformation of lamellar perlite grains are indicated: fracture of cementite plates and carbon pulling out from the lattice of the carbide phase. It is indicated that in the dissolution of cementite plates, the interfacial boundaries of “α-phase-cementite” play an important role. The removal of carbon from cementite plates occurs most intensively near defects in ferrite and cementite. The formed nanosized particles of tertiary cementite are unevenly distributed in the ferrite plates; most of them are observed at the locations of ferrite subgrains and interfacial boundaries. This results in non-uniform diffraction contrast in dark-field images of cementite plates. Nanosized particles of cementite can be taken out into the interlamellar space of pearlite colonies in the process of dislocation slip, or they are formed as a result of deformation decomposition, which is less likely. The fragmentation of ferrite and cementite plates is revealed and azimuthal components of total misorientation angles are estimated. The mechanisms of mass transfer of carbon atoms over interstitial sites, deformation vacancies, dislocation tubes, grain boundaries and fragments are considered. According to all the established patterns of the cementite substructure transformation, a comparison with the results for rails made of hypoeutectoid steel was performed.

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“…Во время эксплуатации рельсы подвергаются износу, поверхностной усталости, в них образуются трещины, происходит выкрашивание [4,6]. В последние годы наблюдается тенденция к увеличению скорости движения поездов и нагрузки на ось, что спо-собствует увеличению частоты появления описанных выше дефектов [7,8].…”

Section: Introductionunclassified

Modelling Methods of Phase Transformation in Bainitic Steel: A Review

Filyakov¹,

Sarychev²,

Chumachkov³

2023

Bulletin of the SibSIU

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Аннотация. К механическим свойствам и эксплуатационным характеристикам рельсовых сталей предъявляются повышенные требования. В связи с этим разработка новых марок рельсовых сталей на сегодняшний день является актуальной задачей. Бейнитные стали, не содержащие карбидов, являются своего рода потенциальными кандидатами для применения на железных дорогах, благодаря своей более высокой вязкости разрушения, сопротивлению усталости и износостойкости. Процесс термической обработки оказывает существенное влияние на механические свойства бейнитных рельсовых сталей. Решающим фактором, определяющим технологию производства рельсовых сталей, является прогнозирование микроструктуры. Для того, чтобы отойти от метода перебора, необходимо создавать математические модели охлаждения рельсов, учитывающие химический состав стали. Для моделирования структурно-фазовых превращений в рельсах для неизотермических условий разрабатываются два подхода: Аврами-Колмогорова с учетом правила Шейля и модель фазового поля. Настоящий обзор посвящен современным исследованиям по компьютерному моделированию структурно-фазовых превращений по этим двум подходам. Первый подход был предложен в 30-е годы XX века для изотермических условий, позднее был развит для неизотермического случая в рамках правила Шейля. В настоящее время к этому подходу интерес со стороны исследователей не ослабевает из-за малого времени расчета. Однако описать пространственное распределение фаз и структур этот метод не может, поэтому активно развиваются методы фазового поля, расчеты по которому могут занимать от нескольких часов до нескольких суток. В представленном обзоре проведен анализ указанных подходов, а также продемонстрированы их ограничения. Ключевые слова: модель фазового поля, JMAK, фазовые превращения, бейнитная сталь, рельсы Финансирование. Исследование выполнено за счет гранта Российского научного фонда № 22-79-10229, https://rscf.ru/project/22-79-10229/?CODE=22-79-10229#.

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Formation mechanism of brown etching layers in pearlitic rail steel

Cited by 10 publications

References 57 publications

Influence of thermal loading parameters and microstructure on the formation of stratified surface layers on railway wheels

Influence of thermal loading parameters and microstructure on the formation of stratified surface layers on railway wheels

Evolution of Cementite Substructure of Rails from Hypereutectoid Steel during Operation

Modelling Methods of Phase Transformation in Bainitic Steel: A Review

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