DOI: 10.52150/2522-9117-2024-38-632-643
Movchan Oleksandr Volodymyrovych, Ph. D. (Tech.), Senior Researcher, Ukrainian State University of Science and Technologies, Lazaryana St., Dnipro, 49010, Ukraine. ORCID 0000-0003-1543-7160
Chornoivanenko Kateryna Oleksandrivna, Ph. D. (Tech.), Associate professor, Ukrainian State University of Science and Technologies, 2 Lazaryana St., Dnipro, 49010, Ukraine. ORCID 0000-0003-1613-7784
REGULARITIES OF PHASE AND STRUCTURAL TRANSFORMATIONS IN THE Fe-Cr-Ti-C SYSTEM DURING CARBURINATION
Abstract. Diffusion carburization of ferrite alloyed with carbide-forming stabilizing ferrite components under certain conditions leads to the cooperative disintegration of ferrite into austenite and special carbide with the formation of eutectoid-like plate-rod colonies. Studying the conditions for the formation of austenite-carbide colonies shows that the driving force behind the growth of colonies is the influx of carbon. At the same time, it is necessary that carburization of ferrite simultaneously leads to austenitization and carbide formation. The analysis of the diagrams of the composition of the Fe-Cr-C and Fe-Ti-C experimental systems with different contents of carbide-forming elements showed that at a certain concentration and temperature, cooperative disintegration of ferrite into austenite and carbides is possible. The regularities of structure formation and phase transformations in the surface layer during carburization were determined depending on the processing parameters. The temperature interval for the formation of austenite-carbide colonial structures, similar to eutectoid ones, which are a natural composite material, during carburization of highly alloyed iron alloys of the Fe-Cr-Ti-C system as a result of joint and simultaneous carbide formation and recrystallization has been established. Complex research methods established the transformation patterns of the α → γ transformation front. It is shown that the formation of the cellular recrystallization front is carried out under the influence of concentration gradients caused by the redistribution of the main alloying element in front of the transformation front. Electron microscopic studies of the austenite-carbide colonies were conducted, which showed that the austenite-carbide colony is a single bicrystal. Martensitic plates are mainly oriented parallel to the carbide rods, which have a cubic facet. Joint electronograms of carbide and austenite showed the presence of an orientational relationship between these phases.
Keywords: carburization, diffusion, phase transformation, carbide formation, colonies, state diagram
DOI: https://doi.org/10.52150/2522-9117-2024-38-632-643
For citation: Movchan, O. V., & Chornoivanenko, K. O. (2024). Regularities of phase and structural transformation in the Fe-Cr-Ti-C system during carburization. Fundamental and applied problems of ferrous metallurgy, 38, 632-643. https://doi.org/10.52150/2522-9117-2024-38-632-643
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