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Foundry and Metal Science
ArticleName Features of structure formation of graphite inclusions in ductile cast iron during casting and hot plastic deformation
DOI 10.17580/chm.2023.04.02
ArticleAuthor A. I. Pokrovsky
ArticleAuthorData

Physical and Technical Institute of the National Academy of Sciences of Belarus, Minsk, Republic of Belarus:

A. I. Pokrovsky, Cand. Eng., Associate Professor, Head of the Laboratory of High Pressures and Special Alloys, e-mail: arturu@tut.by

Abstract

It is shown that nucleation and growth of a spherical graphite inclusion during solidification of a cast iron is a rather complex and multistage process, and it can be described by several simultaneously acting mechanisms. In this paper, the mechanism of nucleation on oxide inclusions and the adsorption mechanism are considered to be preferable. Metallographic evidences of the polycrystalline structure of a spherical graphite inclusion, which consists of prisms with a base close to a hexagon, and of the layer-by-layer growth of flakes in the radial direction are presented. Mathematical modeling has revealed a number of important technological parameters, including the dependence of the diffusion growth rate of a spherical graphite inclusion in ductile cast iron on the crystallization time. A hypothesis has been put forward that graphite inclusions in the cast iron undergo plastic deformation during hot forming without any traces of destruction into segments or turning into powder. The hypothesis is experimentally confirmed by electrolytic etching of the metal matrix and studying the "bare" surface of inclusions, both in the as-cast and in deformed iron. A mechanism of plastic deformation of spherical graphite inclusions in a metal matrix is proposed. It consists in sliding of prismatic sectors (blocks) of the graphite relative to each other and wedging out of the central ones. The deformation process is very short, it lasts about 1 second. After completion of the deformation, interatomic bonds are recovered along the shortest interatomic distances.
The work was carried out at the Physical and Technical Institute of the National Academy of Sciences of Belarus (Minsk) within the framework of the State Scientific Research Institute "Electromagnetic Technologies", task No. 3.3.3.

keywords Ductile cast iron, casting, hot plastic deformation, microstructure, graphite inclusions, internal structure and morphology of inclusions
References

1. Leushin I. О., Panov А. G. Current trends in cast iron production. Chernye Metally. 2021. No. 7. pp. 32–40. DOI: 10.17580/chm.2021.07.02.
2. Stefanescu D. M. Solidification and modeling of cast iron – A short history of the defining moments. Materials Science and Engineering. A. 2005. Vol. 413-414. pp. 322–333.
3. Alonso G., Larrañaga P., Stefanescu D. M., DelaFuente E., Natxiondo A., Suarez R. Kinetics of nucleation and growth of graphite at different stages of solidification for spheroidal graphite iron. International Journal of Metalcasting. 2017. Vol. 11. pp. 14–26.
4. Ghassemali E., Hernando J. C., Stefanescu D. M. et al. Revisiting the graphite nodule in ductile iron. Scripta Materialia. 2019. Vol. 161. pp. 66–69.
5. Stefanescu D. M. The Meritocratic ascendance of cast iron: from magic to virtual cast iron. International Journal of Metalcasting. 2019. Vol. 13, Iss. 4. pp. 726–752.
6. Alonso G., Stefanescu D. M., Larranaga P., Suarez R. Graphite nucleation in compacted graphite cast iron. International Journal of Metalcasting. 2020. Vol. 14. pp. 1162–1171.
7. Zanardi F., Mapelli C., Barella S. Reclassification of spheroidal graphite ductile cast irons grades according to design needs. International Journal of Metalcasting. 2020. Vol. 14, Iss. 3. pp. 622–655.
8. Ivanov V. G., Pirozhkova V. P., Lunev V. V. Study of the structure and formation of nodular graphite inclusions in ductile cast iron. Vostochno-Evropeyskiy zhurnal peredovykh tekhnologiy. 2016. Vol. 3. No. 5 (81). pp. 31–36.
9. Naydek V. L., Neizhko I. G., Gavrilyuk V. P. Nodular graphite in cast irons. Protsessy litya. 2012. No. 5 (95). pp. 33–42.
10. Naydek V. L., Vekhovlyuk А. М. Some reflections on the mechanism of nodular graphite formation in cast iron. Protsessy litya. 2014. No. 1 (103). pp. 47–54.
11. Leushin I. О., Dubinskiy V. N., Korovin V. А., Galkin V. V., Grachev А. N., Pryanichnikov V. А. Hot deformation of nodular cast iron: production implementation. Chernye Metally. 2007. No. 4. pp. 17–19.
12. Dmitriev I. А., Sobolev B. М., Rybalkin А. А. Nodular cast iron forming (review). Uchenye zapiski Komsomolskogo-na-Amure gosudarstvennogo tekhnicheskogo universiteta. 2012. No. 3 (1). pp. 83–86.
13. Sukhanov D. А., Arkhangelskiy L. B., Plotnikova N. V. Plastic deformation of white cast irons. Obrabotka metallov. 2017. No. 4 (77). pp. 43–54. DOI: 10.17212/1994-6309-2017-4-43-54.
14. Dolzhenko А. М., Pushkarenko N. V., Ryazantseva V. S. Cold plastic deformation of highcopper cast irons. Innovatsionnye tekhnologii v mashinostroenii, obrazovanii i ekonomike. 2018. No. 1–4 (7). pp. 32–35.
15. Soldatov V. G., Ilyushkin D. А., Petrakov О. V. Study of the plasticity of white alloy cast iron. Vestnik Bryanskogo gosudarstvennogo tekhnicheskogo universiteta. 2019. No. 2 (75). pp. 28–32.
16. Nikishkina А. B., Bulychev V. V. Simulation of the depth of hardening of parts made of gray cast iron during processing by surface plastic deformation. Inzhenernyi vestnik Dona. 2022. No. 11. 7980.
17. Baranov D. А. Influence of heat treatment on the deformability of ductile iron. Metallurgiya mashinostroeniya. 2003. No. 4. pp. 32–36.
18. Baranov A. А. Spheroidization of graphite during heat treatment of deformed ductile iron. Fizika metallov i metallovedenie. 2004. No. 2. pp. 98–103.
19. Pokrovskiy А. I. Hot plastic deformation of cast iron: structure, properties, technological foundations. Minsk: Belaruskaya navuka, 2010. 256 p.
20. Pokrovskiy А. I., Khrol I. N. Comparative studies of ductile iron fractures in cast and deformed states. Lityo i metallurgiya. 2015. No. 4 (81). pp. 131–146.
21. Bahadori-Fallah J., Farshidi M. H., Kiani-Rashid A. R. Equal channel angular pressing of spheroidal graphite cast iron. Materials Research Express. 2019. Vol. 6. No. 6. 066542. DOI: 10.1088/2053-1591/ab0dcf.

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