Volgograd State Technical University, Russia, Volgograd:

M. V. Kirilichev, Cand. Eng., Head of the Laboratory, Dept. of Technology of Materials, e-mail: tecmat@vstu.ru
N. A. Zyuban, Dr. Eng., Prof., Dept. of Technology of Materials, e-mail: tecmat49@vstu.ru
D. V. Rutsky, Cand. Eng., Associate Prof., Head of the Dept. of Technology of Materials, e-mail: drutskii@vstu.ru

National University of Science and Technology "MISiS", Russia, Moscow:
D. S. Tolstykh, Deputy Director of the Advanced Engineering School "Materials Science, Additive and End-to-End Technologies", e-mail: Tolstykh.DS@misis.ru

Abstract: Microsegregation processes are the primary link in the formation of chemical heterogeneity in the volume of blanks. If certain methods and technologies have been developed to control zonal segregation heterogeneity, which can significantly reduce the manifestations of this defect, then in the case of interdendritic segregation, which depends mainly on the chemical composition and crystallization rate, the development of such methods is associated with certain difficulties. In this work, we studied the features of the formation of microsegregation inhomogeneity in laboratory ingots weighing 40 kg of low-carbon low-alloy steels cast under various cooling conditions, and in a vacuum ingot weighing 24.2 tons of steel 38KhN3MFA. It was found that in laboratory ingots, the determining factor affecting microsegregation processes is the initial chemical composition, in particular the sulfur content, an increase in the concentration of which contributes to the activation of microsegregation processes for almost all elements. Changing the temperature conditions of cooling to a greater extent affects the parameters of the structure. In a large ingot, the change in the concentration of elements both in the axes of the dendrites and in the interdendritic spaces is closely related to the features of the formation of the macrostructure. A more stable distribution of elements is observed on the lower horizon of the ingot, which is due to accelerated crystallization processes due to the cooling effect of the massive tray. The change in the structure parameters depends on the geometric dimensions of the ingot; in the zone of columnar crystals, the dendritic parameter has the highest value.
The study was carried out with the financial support of Volgograd State Technical University within the framework of scientific project No. 6/469-22.

1. Kostyleva L. V. Creation of new scientific principles for strengthening iron-carbon alloys based on the development of the theory of crystallization and microsegregation: Dissertation … of Doctor of Engineering Sciences. Volgograd: VolgGTU, 2002, 361 p.
2. Romashkin A. N., Dub V. S., Tolstykh D. S., Ivanov I. A., Malginov A. N. Prediction of carbon segregation over the cross section of steel forging ingots. Metallurg. 2016. No. 8. pp. 28–41.
3. Kostyleva L. V., Santalova E. A., Gabelchenko N. I., Ilinskiy N. V. Concentration dependence of the dispersion of the dendritic structure in alloys of binary systems. Metallovedenie i termicheskaya obrabotka metallov. 2008. No. 7 (637). pp. 34–38.
4. Yang W., Zhao J., Song S., Qiu S, Numerical simulation of filling and solidification process of large steel ingot. Special Casting and Nonferrous Alloys. 2014. Vol. 34, Iss. 2. pp. 149–152.
5. Romashkin A. N., Dub V. S., Tolstykh D. S., Ivanov I. A., Malginov A. N. Criteria for assessing the propensity of steel to segregation in forging ingots. Metallurg. 2017. No. 10. pp. 35–40.
6. Dub V. S., Romashkin A. N., Malginov A. N., Ivanov I. A. et al. Study of the influence of the configuration of forge ingots on the distribution of chemical elements over their cross section. Problemy chernoy metallurgii i materialovedeniya. 2014. No. 1. pp. 5–18.
7. Rutskiy D. V., Zyuban N. A., Gamanyuk S. B. Production of ingots with favourable location of internal defects owing to varying the features of solidification of its head part. CIS Iron and Steel Review. 2016. Vol. 12. pp. 22–25.
8. Fan Zhang, Hong-gang Zhong, Yu-qian Yang. Improving ingot homogeneity by modified hot-top pulsed magneto-oscillation. Journal of Iron and Steel Research International. 2022. Vol. 29. pp. 1939–1950.
9. Duan Zhen-Hu, Shen Hou-Fa, Liu Bai-Cheng. A Numerical Study of the Effect of Multiple Pouring on Macrosegregation in a 438-Ton Steel Ingot. Acta metallurgica sinica-english letters. 2015. Vol 28. No. 9. pp. 1123–1133.
10. Zyuban N. A., Rutskiy D. V., Gamanyuk S. B., Konovalov S. S. Forged ingots: quality problems and new approaches. Chernye Metally. 2014. No. 7. pp. 17–21.
11. Zhang C., Shahriari D., Loucif A., Melkonyan H., Jahazi M. Influence of thermomechanical shrinkage on macrosegregation during solidification of a large-sized high-strength steel ingot. The International Journal of Advanced Manufacturing Technology. 2018. Vol. 99. pp. 3035–3048. DOI: 10.1007/s00170-018-2695-1
12. Kovalenko V. S. Metallographic reagents: handbook. Moscow: Metallurgiya, 1981. 120 p.
13. Khvorinov N. I. Krystalisace a hestejnorodost oceli. Translated from Czech. Moscow: Mashgiz, 1958. 392 p.
14. Skrebtsov A. M., Kuzmin Yu. D., Sekachyov A. O., Terzi V. V. Dendritic segregation in iron alloys depending on the mass of additional elements and their physical properties. Izvestiya vysshikh uchebnykh zavedeniy. Chernaya metallurgiya. 2014. Vol. 57. No. 9. pp. 52–55.
15. Ilikbaev I. V., Pupyshev D. P. Influence of dendritic segregation on the structure and properties of heat-resistant steel 15Kh2NMFA. Ural School of Metallurgists. Proceedings of the XIX International scientific and technical Ural school-seminar of metallurgists – young scientists. (Ekaterinburg, November 19–23, 2018). pp. 149-152.
16. Sychkov А. B., Bigeev V. А., Potapova М. V., Isaev М. К. Consequences of microphysical segregation of chemical elements in welding steels. Proceedings of the XV International Congress of Steelmakers. Moscow – Tula. (15–19 October 2018). pp. 349–356.
17. Gayduk S. V., Kononov V. V., Nalesnyi N. B. Investigation of dendritic segregation and phase inhomogeneity in heat-resistant corrosion-resistant nickel alloys. Vestnik dvigatelestroeniya. 2006. No. 1. pp. 150–154.