Babachenko Alexander Ivanovich, Dr. Sci., (Engin.), Senior Research Scientist, Director, Iron and Steel Institute named after Z.I. Nekrasov of the NAS of Ukraine, Academican Starodubova square, 1, Dnipro, Ukraine, 49107; e-mail: a_babachenko@i.ua, ORCID 0000-0003-4710-0343
Kononenko Anna Andreevna, PhD (Engin.), Senior Researcher, Iron and Steel Institute named after Z.I. Nekrasov of the NAS of Ukraine, Academican Starodubova square, 1, Dnipro, Ukraine, 49107; e-mail:perlit@ua.fm, a_kononenko@inbox.ru ORCID 0000-0001-7446-4105;
Kholin Artem Nikolaevich, PhD (Engin.), Senior Researcher, Iron and Steel Institute named after Z.I. Nekrasov of the NAS of Ukraine, Academican Starodubova square, 1, Dnipro, Ukraine, 49107;

Investigation of the decay kinetics of austenite with continuous cooling
K76F steel for wide-gauge railway rails

Abstract. The aim of the work is to study the kinetics of decomposition of
supercooled austenite with continuous cooling of steel for railway rails with a
high content of manganese and micro-alloyed vanadium. The relevance of the
work is the need to determine the possibility of producing rails from K76 F
steel according to foreign standards, in particular EN 13674-1-2011. During the
research, a thermo-kinetic diagram was constructed with different cooling rates
for samples of K76F steel heated by the heating mode for quenching the rails in
an induction unit at the heat treatment site at Azovstal Iron and Steel Works.
Dilatometric studies have shown that when samples are heated at a rate of
300С/min in steel for railway rails, polymorphic  -transformation begins at
temperature 7350С (Ас1), ends at 7600С (Ас3). It is established that the
temperatures of the beginning and completion of the formation of ferrite, perlite
and bainite decrease with increasing cooling rate. With an increase in the rate
of cooling, the morphology changes and the dispersion of perlite increases –
from the middle plate of frequent perlite to highly dispersed sorbitol structures
and quenching troostite. It was concluded that in the studied steel grade K76F
with 0.80%С, 0.25%Si, 0.97%Mn, 0.055%V, it is impossible to achieve
hardness above 400НВ without the formation of bainite. For the manufacture of
high-strength rails of category R400HT EN 13674-1-2011, it is necessary to
create steel of a new chemical composition. It is shown that it is possible to
develop grounded reinforcing heat treatment mode and to increase the
operational reliability of rails by defining critical points and studying the
318
«Фундаментальные и прикладные проблемы черной металлургии. – 2018. – Вып.32
«Fundamental and applied problems of ferrous metallurgy». – 2018. – Collection 32
«Fundamental’nye i prikladnye problemy černoj metallurgii». – 2018. – Vypusk 32
kinetics of decomposition of supercooled austenite with continuous cooling of
steel.
Keywords: railway rails, properties, research, kinetics of decomposition of
supercooled austenite, cooling rate, heat treatment modes
Reference
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