SPECIFICATION OF THE FULL EQUILIBRIUM PHASE DIAGRAM OF THE IRON-CARBON SYSTEM BASED ON THE THEORETICAL AND EXPERIMENTAL INVESTIGATIONS

1 SIDOROV Evgeny
Institution:
1 Vladimir State University, Vladimir, Russian Federation, sidorov.ev@mail.ru
Conference:
27th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, May 23rd - 25th 2018
Proceedings:
Proceedings 27th International Conference on Metallurgy and Materials
Pages:
1705-1709
ISBN:
978-80-87294-84-0
ISSN:
2694-9296
Published:
24th October 2018
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
14 views / 2 downloads
Abstract

In 2018 it is 150 years since D.K. Chernov, the metallurgical science expert, made the report on the results of the research of the Fe-C alloy samples and ingots and for the first time ascertained the presence of the critical points, i.e. phase transitions. The work of D.K. Chernov served as the beginning of the construction of the iron-carbon diagram. A great amount of research on the construction and specification of the iron-carbon phase diagram has been carried out during the past period.In the present work a critical analysis of the generally recognized combined iron-carbon and iron-cementite diagram is given, theoretical and experimental investigations by studying the microstructures of the iron-carbon alloy samples quenched from various temperatures have been carried out. Based on the research, a full equilibrium phase diagram of the iron-carbon system has been constructed, in which the non-variant three-phase equilibrium ferrite+graphite ⇔ cementite at the temperature 727 °C, two-phase equilibrium ferrite+graphite in the temperature range 738 – 727 °C and two two-phase regions ferrite+cementite (up to 6.67 wt.% C) and cementite+graphite (more than 6.67 wt.% C) at the temperatures below 727 °C are present. It is shown that cementite cannot be formed in the iron-carbon alloys at the temperatures exceeding 738 °C at high cooling rates. The author considers expedient not to use the version of the metastable iron-cementite phase diagram and to exclude the designation of the alloy microstructures (perlite and ledeburite) in the phase diagram.

Keywords: Phase diagram, iron-carbon system, microstructure, equilibrium, metastable system
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