Please use this identifier to cite or link to this item: https://elar.usfeu.ru/handle/123456789/8923
Title: Critical Grain Size Estimation in the γ-α Martensitic Transformation with Athermal Macrokinetics by the Example of Fe-Ni-Cr System
Authors: Kashchenko, M. P.
Kashchenko, N. M.
Korolev, A. V.
Oglezneva, S. A.
Chashchina, V. G.
Issue Date: 2019
Publisher: Pleiades Publishing
Citation: Kashchenko, M. P. Critical Grain Size Estimation in the γ-α Martensitic Transformation with Athermal Macrokinetics by the Example of Fe-Ni-Cr System / M. P. Kashchenko, N. M. Kashchenko, A. V. Korolev [et al.] // Physical Mesomechanics. – 2019. – Vol. 22. – Iss. 3. – P. 203-208.
Abstract: The existence of the critical grain size Dc for reconstructive martensitic transformations implies that at austenite grain diameters D smaller than Dc the transformation is suppressed during cooling down to absolute zero temperature. In the case of athermal macrokinetics, martensite crystals divide connected (free from boundaries) volumes of austenite, which allows the use of fractal type models for the processing of results. This study shows that the symmetric model of orthogonal coupling of martensite crystals, developed to estimate the amount of formed martensite in single-crystal samples, can also be applied for an initial polycrystalline sample with a known austenite grain size distribution. A step-by-step algorithm for the theoretical estimation of Dc is proposed under the assumption that the formation of each succeeding generation of martensite crystals begins in the largest continuous volumes of retained austenite. If the estimated cumulative fraction of martensite coincides with the observed resultant value, the count is stopped, and the size of the largest of untransformed continuous volumes of retained austenite is taken as Dc. A detailed analysis of results was carried out for a sample of the alloy Fe - 29.96%Ni - 1.83% Cr in which the volume fraction of the largest grains (with the size D = 310–315 µm) was approximately 58% and four autocatalytic bursts were detected during cooling; the bursts corresponded mainly to the generations of martensite crystals associated with the austenite regions related to the transformation of the initial coarse grains. The amount of martensite crystals was determined by the increase in magnetization and by X-ray diffraction. With the cumulative fraction of martensite ≈70%, Dc was estimated to be ≈ 25.44 µm. © 2019, Pleiades Publishing, Ltd.
Keywords: ATHERMAL MACROKINETICS
CRITICAL GRAIN SIZE
DYNAMIC THEORY
MARTENSITIC TRANSFORMATIONS
SYMMETRIC MODEL OF ORTHOGONAL COUPLING OF CRYSTALS
AUSTENITE
CHROMIUM ALLOYS
GRAIN SIZE AND SHAPE
IRON ALLOYS
MARTENSITE
SINGLE CRYSTALS
TERNARY ALLOYS
ABSOLUTE ZERO TEMPERATURE
CRITICAL GRAIN SIZES
DYNAMIC THEORY
MACROKINETICS
POLYCRYSTALLINE SAMPLES
STEP-BY-STEP ALGORITHM
SYMMETRIC MODEL
THEORETICAL ESTIMATION
MARTENSITIC TRANSFORMATIONS
URI: https://elar.usfeu.ru/handle/123456789/8923
DOI: 10.1134/V1029959919030056
SCOPUS: 2-s2.0-85067868665
WoS: WOS:000472979000005
RSCI: 41679821
Appears in Collections:Научные публикации, проиндексированные в SCOPUS и WoS CC

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