Development of an Innovative Digital Cooling Technology (Differential Heat Treatment) for EVRAZ NTMK Rails

Kushnarev, A. V.; Смирнов, Л. А.; Kirichkov, A. A.; Dobuzhskaya, A. B.; Khlyst, S. V.; Kuzmichenko, V. M.; Khlyst, I. S.; Gontar, A. V.; Белокурова, Е. В.

doi:10.3103/s0967091220060042

Cited by 3 publications

(1 citation statement)

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“…Данное сочетание свойств может быть получено путем реализации технологии закалочного охлаждения, обеспечивающей формирование в головке рельса достаточно глубокого слоя с однородной дисперсной мик роструктурой с мелким исходным зерном аустенита [4][5][6][7]. Решение такой сложной металловедческой задачи возможно при использовании отдельного печного или индукционного нагрева рельсов под закалку [8,9] и охлаждении закалочной средой с высокой охлаждающей способностью (сжатый воздух контролируемой влажности [10][11][12], водовоздушная смесь [12], спрейерное охлаждение водой [13,14]).…”

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Development of rails of a new category for use in particularly harsh operating conditions

Tokmakova

Perkov

Ivanov

et al. 2022

Russian Railway Science

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Introduction. In the conditions of an annual increase in load stress on the roads of the Eastern Polygon, an effective technical solution to the problem of an increased number of rolling stock derailments due to rail breakage is the creation of rails for cold climate conditions with increased hardness to increase wear resistance and contact endurance with simultaneously high values of impact strength. Such a set of properties can be achieved by using separate heating for quenching and cooling with a quenching medium with a high cooling capacity. Rails manufactured using this technology will belong to a new category. In this regard, the purpose of this work was to create a new category of rails for their use in particularly harsh operating conditions.Materials and methods. In this paper the effect of separate induction heating before differentiated quenching with compressed air of controlled humidity on the microstructure and mechanical properties (hardness, mechanical properties during tensile and impact tests, endurance limit, cyclic crack resistance) of rails of type R65 was investigated.The results of the study. A comparative analysis of the results obtained with similar indicators for rails of the DT350, DT350NN and DT370IK categories according to GOST R 51685-2013 was carried out. Studies of the chemical composition, mechanical properties, hardness on the rolling surface of the rail head and cross-section, as well as the microstructure of the rails of the experimental batch showed compliance with the requirements of GOST R 51685-2013 for rails of categories DT350, DT370IK, DT350NN.Discussion and conclusion. It is shown that as a result of the application of differentiated thermal hardening of the rail using compressed air of controlled humidity as a quenching medium, a new category of DTO350NN rails was obtained, characterized by a favorable combination of strength properties, plasticity characteristics and brittle fracture resistance indicators. Rails of the new category can be recommended for use in particularly severe operating conditions (in curved sections of the track of a small radius at low temperatures), including on the roads of the Eastern Polygon.

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Development of rails of a new category for use in particularly harsh operating conditions

Tokmakova

Perkov

Ivanov

et al. 2022

Russian Railway Science

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Elaboration of standards and quality of railway rails

Смирнов

Rabovskii

Dobuzhskaya

et al. 2020

Černaâ metallurgiâ. Bûlletenʹ naučno-tehničeskoj informacii

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Russian national standards for rails establish technical requirements, acceptance rules and quality control methods. These are very important to ensure the quality and service durability of rails. Requirements for rail production variation within a period from 1960 to the present considered, peculiarities of their accounting in the standards shown. It was demonstrated that stricter requirements to rails resulted in the development of new steel compositions, the creation and introduction of new technological processes in steel production, rail rolling and heat treatment, as well as new methods of production quality control. Basic technical requirements for rails produced according to the national standard of theRussian Federationand to the European Norm presented. It was pointed out that the current national standard GOST R 51685‒2013 was elaborated accounting the requirements of the latest foreign standard EN 3674-1:2011+A1:2017. However, the former is not equivalent to the latter because it pertains to Russian rail types and contains requirements corresponding to the Russian climatic and geographical conditions, as well as the track facilities system used by OJSC RZD. It was shown that rails, meeting the current standard requirements, in terms of operational resistivity exceed the resistivity level of best foreign analogues. At present, a new standard is being elaborated accounting the need of increasing the service life of railway rails under conditions of high load, low climatic temperatures, higher-speed combined train operation and high-speed running, and high working capacity. The list of key issues presented, that are mirrored in the new standard draft, which accounts for the goal of mastering new rail categories and the increased requirements of OJSC RZD to rails quality.

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Numerical simulations of gradient cooling technique for controlled production of differential microstructure in steel strip or plate

Pohjonen

2021

AIMSMATES

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<abstract><p>Numerical studies were conducted to investigate the applicability of cooling strategies for controlledly producing a microstructure in the steel strip or plate, which changes as function of the plate length. In the numerical simulations, the water spray cooling was varied as function of the plate length and as a result, the different parts of the plate were cooled at different rates. We applied the previously developed numerical code where the transformation latent heat is coupled with the heat conduction and transfer model, which has also been calibrated to correspond to experimental laboratory cooling line. The applicability of the method was investigated for controlledly creating alternating bainite and polygonal ferrite regions in plates of two different thicknesses (0.8 cm and 1.2 cm thick plates) by cooling different parts of the plate to different temperatures before switching off the water cooling so that polygonal ferrite forms in the part which has been cooled to higher temperature and bainite forms in the low temperature part. The simulation results indicate that the controlled production of such alternating regions is possible, but the resulting regions in the studied scenario cannot be very thin. The transition regions between the ferrite and bainite regions in the simulated cases are in the range of 5–15 cm. Controlled production of zones consiting of softer phase in the otherwise bainitic steel could offer a possibility for creating designed tracks in a steel bainitic strip or plate, where the mechanical working or cutting of the material is easier.</p></abstract>

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Development of an Innovative Digital Cooling Technology (Differential Heat Treatment) for EVRAZ NTMK Rails

Cited by 3 publications

References 0 publications

Development of rails of a new category for use in particularly harsh operating conditions

Development of rails of a new category for use in particularly harsh operating conditions

Elaboration of standards and quality of railway rails

Numerical simulations of gradient cooling technique for controlled production of differential microstructure in steel strip or plate

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