Characterization of deformed pearlitic rail steel

Nikas, Dimitrios; Meyer, Knut Andreas; Ahlström, Johan

doi:10.1088/1757-899x/219/1/012035

Cited by 7 publications

(5 citation statements)

References 5 publications

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“…In the transport industry, railway consists of 1,370,782 km length of rail track worldwide [1] and this length is still growing. In this entire rail network, the pearlitic steels are the most commonly used steels [2]. Failure in pearlitic railway steels is strongly affected by the detrimental microstructural changes on the rail raceway due to the wheel-rail contact.…”

Section: Introductionmentioning

confidence: 99%

In situ study on fracture behaviour of white etching layers formed on rails

et al. 2019

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Failure in engineering materials like steels is strongly affected by in-service deleterious alterations in their microstructure. White Etching Layers (WELs) are an example of such inservice alterations in the pearlitic microstructure at the rail surface. Cracks initiate in the rails due to delamination and fracture of these layers and propagate into the base material posing severe safety concerns. In this study, we investigate the microscale fracture behaviour of these WELs. We use in situ elastic-plastic fracture mechanics using J-integral to quantify the fracture toughness. Although usually assumed brittle, the fracture toughness of 21 -25 MPa√m reveals a semi-brittle nature of WELs. Based on a comparison of the fracture toughness and critical defect size of WELs with the undeformed pearlitic steels, WELs are detrimental for rails. In the micro fracture tests, WELs show crack tip blunting, branching, and significant plasticity during crack growth due to their complex microstructure. The fracture behaviour of the WELs is governed by their microstructural constituents such as phases (martensite/austenite), grain size, dislocation density and carbon segregation to dislocations and grain boundaries. We observed dislocation annihilation in some martensitic grains in the WELs which also contributes to their fracture behaviour. Additionally, the straininduced transformation from austenite to martensite affects the crack growth and fracture.

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Section: Introductionmentioning

confidence: 99%

In situ study on fracture behaviour of white etching layers formed on rails

et al. 2019

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“…In the work [34] it was found that in the samples taken from the exploited section of rail made of R260 steel with large deformations present close to the surface, there is a large hardness gradient with high hardness close to the surface, which is most likely the result of work hardening.…”

Section: Investigation Resultsmentioning

confidence: 99%

Structure and Properties of the S49 Rail after a Long Term Outdoor Exposure

Konieczny¹,

Labisz²

2022

Adv. Sci. Technol. Res. J.

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The subject of the research in this work was the S49 rail made of R260 rail steel (1.0623). The carried out investigations concern microstructure tests and tests of mechanical properties of rails after several years of exposure in the open air without usage. The purpose of the work was to determine on the basis of the results of research the possibilities of using the tested rail for usage and application for the construction of tracks on railway sidings. For investigations there were used diverse techniques reaching such engineering materials investigations like light or scanning electron microscope for microstructure investigations, as well as hardness and microhardness test were performed for determinations of the microstructural changes occurred in the upper area of the rails surface. The microstructure changes concerns especially the ferritic and pearlitic structure and the breaks in the present carbide mesh. During investigations it was found out that the tested railway rails are fully useful for application, after machining to achieve required dimensional parameters. It is also of high importance, of the economical point of view, that their price, also in case of earlier installation of the rails, may be lower than the current price off ered on the marked for a entire new product. The price diff erence reaches dimensions in the range of 5-10%.

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“…In a softer ferrite matrix, oriented cementite lamellae make up the lamellar microstructure known as pearlite [27]. This microstructure offers superior wear resistance and strength for railway applications [28]. Figure 12 shows the microstructure of weld metal near the fusion line of thermite weld.…”

Section: Optical Microscopymentioning

confidence: 99%

“…Some ferrite phases can be seen in the pearlite microstructure. In SEM images, ferrite appears in dark due to the contrast of SEM [28]. The only difference between the two SEM images is the detectors; elsewhere, the settings were identical.…”

Section: Scanning Electron Microscopymentioning

confidence: 99%

Influences of preheating parameters on the quality of weld by thermite rail welding

Burapa,

Oo,

Sangwiman

et al. 2024

Mater. Res. Express

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The major goal of this study is to enhance the mechanical and metallurgical characteristics of rail steel grade R260 joined by thermite welding under various preheating conditions, including preheating time and gas pressure. Mainly two conditions, referred to as the normal condition and improved condition, are carried out for experiments. Prior to welding, the normal condition was preheated using liquefied petroleum gas (LPG) and oxygen gas pressures of 1 bar and 4.5 bar for 3 minutes, and the improved condition was preheated using liquefied petroleum gas and oxygen gas pressures of 1.2 bar and 4.5 bar for 6 minutes and 30 seconds. To investigate the mechanical and physical properties, micro-Vickers hardness tests, tensile tests and slow bending tests were also carried out. Welded metal in normal condition has many defects, including gas holes and shrinkage cavities. When comparing the Normal Condition to the Improved Condition, the Improved Condition demonstrates significantly more bending load and deflection. Specifically, the thermite welded rail sample of Improved Condition demonstrated a remarkable ability to endure bending loads of 108 tonnes and a deflection of 16 mm, and this sample remained unbroken until it exceeded 50% of the standardized deflection limit (10 mm). In addition, the average hardness values for the Improved Condition of the weld metal zone and the heat-affected zone were 331 HV and 289 HV, respectively. The normal condition produced an unsatisfactory fracture surface after slow bending test. This was caused by weld defects at the thermite weld due to inappropriate preheating.

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Characterization of deformed pearlitic rail steel

Cited by 7 publications

References 5 publications

In situ study on fracture behaviour of white etching layers formed on rails

In situ study on fracture behaviour of white etching layers formed on rails

Structure and Properties of the S49 Rail after a Long Term Outdoor Exposure

Influences of preheating parameters on the quality of weld by thermite rail welding

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