Modeling of kinematic hardening at large biaxial deformations in pearlitic rail steel

Meyer, Knut Andreas; Ekh, Magnus; Ahlström, Johan

doi:10.1016/j.ijsolstr.2017.10.007

Cited by 26 publications

(6 citation statements)

References 49 publications

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“…The predeformation method developed by Meyer et al [23] has been used to replicate the anisotropic surface material found in rails. The predeformation process is a cyclic sequence in which test bars are twisted under simultaneous compression, as illustrated and explained in Figure 2a.…”

Section: Predeformation and Reprofilingmentioning

confidence: 99%

“…Consequently, the samples must be small in order to have a well defined and uniform material state. To overcome this limitation, an alternative predeformation technique was proposed by Meyer et al [23], where solid cylindrical test bars are twisted while applying a constant compressive load. With this method, it is possible to achieve shear strains up to approximately 2.3, when using test bars with an initial gauge section diameter of 10 mm.…”

Section: Introductionmentioning

confidence: 99%

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Fatigue Crack Propagation on Uniaxial Loading of Biaxially Predeformed Pearlitic Rail Steel

Gren,

Ahlström

2023

Metals

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Rolling contact fatigue loading causes the surface material in the top of the rail to severely deform. The microstructure aligns along the shear direction and the mechanical behavior in terms of plastic flow becomes anisotropic. Cracks are initiated in the severely deformed surface region and propagates along the direction of microstructure flow lines. However, the effect of large shear deformation on fatigue crack growth is not yet well understood. In this study, uniaxial fatigue crack propagation of undeformed and biaxially predeformed pearlitic rail steel R260 has been investigated. The material was predeformed to different deformation states using combined axial compression and shear deformation, corresponding to material found at different depths in the severely deformed surface layer of rails. Fatigue crack propagation rate was dependent on the material state and influenced by both work hardening and microstructural anisotropy. It was found that predeformed material exhibited lower crack growth rates than undeformed material under this loading condition. The influence of predeformation on the crack growth direction was limited.

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Section: Predeformation and Reprofilingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fatigue Crack Propagation on Uniaxial Loading of Biaxially Predeformed Pearlitic Rail Steel

Gren,

Ahlström

2023

Metals

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“…The surface layer is also severely anisotropic due to rail material roll-out, see ref. 28. The influence of this anisotropy on RCF is complex, and it is currently difficult to give general statements regarding its effects on crack initiation and propagation, see ref.…”

Section: Removal Of the Surface Layermentioning

confidence: 99%

Rail machining – current practices and potential for optimisation

Steyn

Paulsson

Ekberg

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part F:

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Current practices on rail machining show large variations in strategies and amount of grinding and milling. To identify reasons for this and suggest strategies to further optimise rail machining, objectives of machining are scrutinised and consequences of not fulfilling objectives are investigated. This leads to a discussion on potentially detrimental effects of rail machining and how to minimise these. With this background, general aspects of rail machining optimisation are discussed. The study shows several means to improve rail machining, but also how the potential is restricted by the current lack of knowledge and predictive models. This prevents quantifying benefits of innovative solutions, and complicates transfer of knowledge between different operational conditions and translations of (scaled and controlled) test results to (full-scale, uncontrolled) operational conditions.

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“…where is the friction stress (60 MPa [5]), is the Hall-Petch constant for R260 pearlite steel, calculated using Eq. (3) and by inserting the flow stress ( ) of the initial material, 534.2 MPa [24], is the thickness of ferrite lamellae, is the orientation factor, taken as 3, α is a constant (0.24) [6], is the shear modulus of ferrite (77.5 GPa) and is the Burgers vector (0.248 nm).…”

Section: Microstructure-strength Relationshipsmentioning

confidence: 99%

Evaluation of local strength via microstructural quantification in a pearlitic rail steel deformed by simultaneous compression and torsion

Nikas

Zhang

Ahlström

2018

Materials Science and Engineering: A

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Pearlitic steels are commonly used for railway rails because they combine good strength and wear properties. During service, the passage of trains results in large accumulation of shear strains in the surface layer of the rail, sometimes leading to crack initiation. Knowledge of the material properties versus the shear strain in this layer is therefore important for fatigue life predictions. In this study, fully pearlitic R260 rail steel was deformed using a bi-axial torsion-compression machine to reach different shear strains. Microstructural parameters including interlamellar spacing, thickness of ferrite and cementite lamellae and dislocation density in the ferrite lamellae, as well as hardness were quantitatively characterized at different shear strain levels. Based on the microstructural observations and the quantification of the microstructural parameters, the local flow stresses were estimated based on boundary strengthening and dislocation strengthening models. A good agreement was found between the estimated flow stresses and the flow stresses determined from microhardness measurements.

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Modeling of kinematic hardening at large biaxial deformations in pearlitic rail steel

Cited by 26 publications

References 49 publications

Fatigue Crack Propagation on Uniaxial Loading of Biaxially Predeformed Pearlitic Rail Steel

Fatigue Crack Propagation on Uniaxial Loading of Biaxially Predeformed Pearlitic Rail Steel

Rail machining – current practices and potential for optimisation

Evaluation of local strength via microstructural quantification in a pearlitic rail steel deformed by simultaneous compression and torsion

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