Bobyr Sergey Vladimirovich, Dr. Sci. (Engin.), Leading Research Scientist, Iron and Steel Institute named after Z.I. Nekrasov of the NAS of Ukraine, Academican Starodubova square, 1, Dnipro, Ukraine, 49107; e-mail:svbobyr07@gmail.com, ORCID 0000-0001-6816-1554
Borisenko Andrey Yurievich, PhD (Engin.), Research Scientist, Iron and Steel Institute named after Z.I. Nekrasovof the NAS of Ukraine, Academican Starodubova square, 1, Dnipro, Ukraine, 49107; e-mail: asbor@ua.fm
Kuksa Oleg Volodimirovich, PhD (Engin.), Researcher, Iron and Steel Institute named after Z.I. Nekrasov of the NAS of Ukraine, Academican Starodubova square, 1, Dnipro, Ukraine, 49107
Loshkarev Dmitry Valerievich, Lead Engineer, Iron and Steel Institute named after Z.I. Nekrasov of the NAS of Ukraine, Academican Starodubova square, 1, Dnipro, Ukraine, 49107

Analysis of phase-structural transformations during cooling of steels, taking into account the deformations and stresses

Abstract. The aim of the work is to study the phase-structural
transformations during cooling of carbon and low-alloy steels, taking into
account the resulting structural deformations and stresses. Low-alloyed steels
with different content of alloying elements – chromium, molybdenum, nickel
and steel, micro-alloyed with vanadium were chosen as the object of research.
The dilatograms of steel samples were used to find the relative expansion of the
steel sample before the start of austenite phase transformation (DA) and the
relative expansion of the steel sample during austenite phase transformation
(DFТ), which are associated with the relative elongation of the sample through a
constant factor K. The parameter DA allows you to find structural stresses that
arise in supercooled austenite steel in the presence of a temperature gradient.
The parameter DFТ characterizes the stresses created by the phase
transformation of austenite. As a result of the performed regression analysis,
dependences were obtained that link the chemical composition of the steel, its
cooling rate, and the parameters DА and DFТ. The analysis of phase-structural
transformations during the cooling of the steel with the occurring deformations
and stresses. An empirical relationship has been established between the
temperatures of the beginning and end of the phase transformation of austenite
in steel, the physicochemical parameters d and Zy, the cooling rate, and the
deformation parameters when the austenite is cooled DA and the phase
2
«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
transformation DFТ. Confirmed the adequacy of the constructed equations. The
obtained regression equations make it possible to calculate the deformation
parameters DA and DFТ and critical points of the steel Ac1 and Ac3 ..
Keywords: carbon and low-alloy steels, cooling, phase-structural transformations, temperature, deformations and stresses
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