Met. litʹe Ukr., 2021, Tom 29, №1, P. 46-53
V.B. Bublikov, Dr. Sci. (Engin.), Senior Research Scientist, Department Chair, e-mail: firstname.lastname@example.org, https://orcid.org/0000-0003-4465-9256
A.V. Narivskyi, Corresponding Member of the NAS of Ukraine, Dr. Sci. (Engin.), Director, e-mail: email@example.com, https://orcid.org/0000-0002-1596-6401
Yu.D. Bachynskyi, PhD (Engin.), Senior Researcher, e-mail: firstname.lastname@example.org, https://orcid.org/0000-0002-5745-1369
Physico-technological Institute of Metals and Alloys of the NAS of Ukraine (Kyiv, Ukraine)
The most common method of making ductile iron castings is green-sand casting. However, this method does not always allow to obtain the desired finegrained structure in castings due to its relatively low cooling rate. The application of the coated metal mould casting method makes it possible to expand the range of casting cooling rate regulation by the change of sandresin coating layer thickness on the metal mould surface. The article presents results of studies on the distribution of chemical composition, structure parameters (diameter and number of nodular graphite particles, ferrite amount) and mechanical properties (tensile strength, yield strength, elongation) of ductile cast iron in castings of thin-walled shells obtained in coated metal moulds with the use of in-mold melt modifying. This technology allowed to obtain castings without the use of risers, increase the casting yield from 45 to 65 % and their dimensional accuracy. At the same time, the surface roughness and value of machining allowances are decreased, which increases the metal utilization rate from 43 up to 88 % and reduce the parts manufacturing labor intensity in 2.1 times. The developed technology provides high indicators of ductile cast iron mechanical properties (Rm ≥ 515 MPa, Rp0,2 ≥ 378 MPa, A ≥ 5.8 %) without carbides formation at crystallization. The castings obtained in this way are well processed by cutting without graphitizing annealing. It is established that the use of our developed ductile cast iron with silicon content 3.2–3.8 wt.% allows to increase the mechanical properties of cast metal (Rm ≥ 600 MPa, Rp0,2 ≥ 450 MPa, A ≥ 8 %).
Keywords: Ductile cast iron, in-mold modifying, coated metal mould, chemical composition, structure, mechanical properties, distribution, alloying.
1. Lerner, Y. (2003). Permanent mold casting of ductile iron. Foundry Management & Technology. URL: https://www.foundrymag.com/issues-and-ideas/article/21925869/permanent-m... (last accessed 10.11.2020).
2. Riebisch, M., Seiler, C., Pustal, B., Bührig-Polaczek, A. (2019). Microstructure of ascast high-silicon ductile iron produced via permanent mold casting. International Journal of Metalcasting, vol. 13, iss. 1, pp. 112-120, doi: https://doi.org/10.1007/s40962-018-0232-5
3. Itofuji, H., Edane, K., Kotani, T., Itamura, M., Anzai, K. (2016). Chill-free permanent mold casting of spheroidal graphite iron. Proceedings of CasTec2016, pp. 98-108.
4. Qizhou, C., Bokang, W. (2008). Recent development of ductile cast iron production technology in China. China foundry, vol. 5,iss. 2, pp. 82-91.
5. Khalil-Allafi, J., Amin-Ahmadi, B. (2011). Influence of mold preheating and silicon content on microstructure and casting properties of ductile iron in permanent mold. Journal of iron and steel research, international, vol. 18, iss. 3, pp. 34-39, doi: https://doi.org/10.1016/S1006-706X(11)60034-4
6. Snezhnoy, R.L., Serebro, V.S. (1977). Development of lined chill molds casting technology. Liteynoe proizvodstvo, no. 11,pp. 28-30 [in Russian].
7. Petrichenko, A.M., Zhabotinskiy, N.P., Puchkanev, A.M., Mozharov, M.V., Yakovlev, F.I. (1975). Ductile iron castings structure control with chill mold lining thickness. Liteynoe proizvodstvo, no. 6, pp. 39-40 [in Russian].
8. Girshovich, N.G. (Ed.) (1978). Cast iron handbook. Leningrad: Mashinostroenie, 758 p. [in Russian].
9. Bublikov, V.B. (2003). Increasing of modifying impact on cast iron structure formation. Foundry. Technologies and Equipment, no. 8, pр. 20-22 [in Russian].
10. Bublikov, V.B. (2008). High-strength cast iron - 60. Foundry. Technologies and Equipment, no. 11, pр. 20-22 [in Russian].
11. Bublikov, V.B., Bachynskyi, Yu.D. (2018). Ductile cast iron: the progress of technologies, an improvement of properties. Metal and Casting of Ukraine, no. 7-8, pр. 7-13 [in Russian].
12. Smirnov, N.V., Dunin-Barkovskij, I.V. (1969). Course of probability theory and mathematical statistics for technical applications. Moscow: Nauka. 512 p. [in Russian].
13. Stepnov, M.N. (1985). Statistical methods of mechanical test results processing: Handbook. Moscow: Mashinostroenie, 232 p. [in Russian].
14. Bunin, K.P., Malinochka, Ya.N., Taran, Yu.N. (1969). Fundamentals of cast iron metallography. Moscow: Metallurgiya, 416 p. [in Russian].
15. Bublikov, V.B., Narivskyi, A.V., Bachynskyi, Yu.D., Yasynskyi, O.O. (2020). Silicon alloyed ductile cast iron and its application. Casting processes, no. 1, pp. 20-29, doi: https://doi.org/10.15407/plit2020.01.020 [in Ukrainian].
16. Weiß, P., Tekavcic, A., Bührig-Polaczek, A. (2018). Mechanistic approach to new design concepts for high silicon ductile iron. Materials Science and Engineering: A, vol. 713, pp. 67-74, doi: https://doi.org/10.1016/j.msea.2017.12.012
17. Mikoleizik, P., Geier, G. (2015). SiWind - Development of materials for offshore wind power plants of the multi megawatt range. Casting Plant & Technology, iss. 2, pp. 8-15.
18. Stan, S., Riposan, I., Chisamera, M., Stan, I. (2019). Solidification characteristics of silicon-alloyed ductile cast irons. Journal of Materials Engineering and Performance, vol. 28, iss. 1, pp. 278-286, doi: https://doi.org/10.1007/s11665-018-3828-2
19. Bauer, B., Mihalic Pokopec, I., Petrič, M., Mrvar, P. (2020). Effect of cooling rate on graphite morphology and mechanical properties in high-silicon ductile iron castings. International Journal of Metalcasting, vol. 14, iss. 3, pp. 809-815, doi: https://doi.org/10.1007/s40962-020-00432-3.