Ural Federal University named after the first President of Russia B. N. Yeltsin, Ekaterinburg, Russia:

A. G. Tyagunov, Assistant Professor
E. E. Baryshev, Senior Researcher
G. V. Tyagunov, Professor
V. S. Mushnikov, Assistant Professor, e-mail: Mushnikov@hotmail.com

Our paper studies the temperature dependences of the specific electrical resistance of samples of the high-temperature alloy ZS6U (ЖС6У), melted at metallurgical plant by using various technologies: 1) vacuum induction remelting (VIR) according to the traditional mode; 2) vacuum induction remelting with hightemperature melt processing (VIR + HTMP); 3) VIR according to the traditional mode followed by electroslag remelting (VIR + ESR); 4) VIR under the traditional mode followed by vacuum-arc remelting (VIR + VAR). For comparison, we also investigated the samples melted at the metallurgical plant according to the mode 1 with a subsequent high-temperature treatment of the melt in the foundry. The temperature dependences of electrical resistance of high-temperature nickel alloys in the liquid state have a complicated form. An alternative melt structure of a high-temperature alloy is proposed. The initial state of the melt after melting is microinhomogeneous, and the doping component atoms form independent structural groups that inherit the features of the solid state. Their nuclei are micro-groups of Me – C with a structure close to carbides, the cladding can serve as dynamic cluster formations, similar in composition and structure to compounds of the NixAly type. The temperature range from melting to the temperature of the anomaly has no irreversible change in the structure of the liquid metal. Irreversible destruction of the shell of the microaggregate begins when heated in the temperature range between the hysteresis and anomaly temperatures. At the same time, the higher the temperature in this region is, the smaller is the size of micro-grouping. It can be assumed that at the temperature of the anomaly, the micro-cladding envelope is completely destroyed; only the nuclei-carbide micro-groups of the Me – C type remain in the melt. Upon subsequent cooling of the molten metal, previously heated above the hysteresis temperature, the previously destroyed micro-groups are not formed again. Due to additional introduction of energy, the usage of remelting (VAR, ESR) makes it possible to lower the temperatures at which an equilibrium state is formed.

1. Cheng J.-Q., Hu X.-J., Gu Y. Development and application of molds for producing large superalloy vacuum electrodes. Foundry. 2016. Vol. 65, No. 9. pp. 917–919.
2. Li F., Fu R., Feng D., Yin F., Tian Z. Microstructure and segregation behavior of Rene 88DT alloy prepared by ESR-SDS. Rare metal Materials and Engineering. 2016. Vol. 45 (6). p. 1437–1447.
3. Zhang Z. W., Niu Y. J., Tian J. J., An N., Gao Y., Wang C., Shi S. F. The effect of remelting on the microstructure and mechanical properties of nickel superalloy. Materials Science Forum. 2016. Vol. 849. pp. 492–496.
4. Schafric R. E., Sprague R. Saga of gas turbine materials. Part II. Advanced Materials and Processes. 2004. Vol. 162, No. 4. pp. 27–30.
5. Kablov E. N., Sidorov V. V., Kablov D. E., Min P. G., Rigin V. V. Melting resource-saving technologies of promising cast and wrought superheat resistance alloys, taking into account all waste type processing. Elektrometallurgiya. 2016. No. 9. pp. 30–41.
6. Filippov Yu. O., Eremin E. N., Sumlenikov V. K., Filippov O. S., Kuzemtsev A. I. Electroslag remelting of wastes of hich-temperature foundry alloys. Mekhanicheskoe oborudovanie metallurgicheskikh zavodov. 2013. No. 2. pp. 55–61.
7. Mitchel A., Reed R. C. The influence of remelting processes on the mechanical properties of forged alloys. High temperature тaterials and processes. 2009. Vol. 28, No. 5. pp. 285–297.
8. Baum B. A. Metallic liquids. Moscow : Nauka, 1978. 135 p.
9. Baum B. A., Khasin G. A., Tyagunov G. V., Klimenkov E. A., Bazin Yu. A., Kovalenko L. V., Mikhaylov V. B., Raspopova G. A. Liquid steel. Moscow : Metallurgiya, 1984. 208 p.
10. Zamyatin V. M., Baum B. A. Non-equilibrium state of metallic melts and other factors, determining the metal products quality. Rasplavy. 2010. No. 3. pp. 12–20.
11. Tyagunov G. V., Baryshev E. E., Tsepelev V. S. et al. Metallic liquids. Steels and alloys. Ekaterinburg : UrFU, 2016. 268 p.
12. Elanskiy G. N., Elanskiy D. G. Structure and properties of metallic melts. Moscow : MGVI, 2006. 228 p.
13. Elanskiy G. N., Kudrin V. A. Structure and properties of liquid metal — melting technology — quality of steel. Moscow : Metallurgiya, 1984. 196 p.
14. Popel S. I., Sitnikov A. I., Boronenkov V. N. Theory of metallurgical processes : tutorial for universities. Moscow : Metallurgiya, 1986. 463 p.
15. Mitchel A. Influence of process parameters during secondary melting of nickel based superalloys. Materia Science and technology. 2009. Vol. 25, No. 2. pp. 186– 190.
16. Ling Wang, Lin Liu, Hongyan Wu, Jianxin Dong, Maicang Zhang. Effect of superheat on the microsegregation and fluid flow tendency during directional solidification of superalloy In718. Chemical Engineering Communications. 2010. Vol. 197, No. 12. pp. 1586–1596.
17. Holz M., Franz H. Modern vacuum metallurgy – Competitive edge at changing market conditions. World of Metallurgy – Erzmetall. 2014. Vol. 67 (4). pp. 230–238.
18. Tyagunov G. V., Baum B. A., Tsepelev V. S., Tyagunov A. G., Vlokh A. N. Measurement of specific electrical resistance by rotating field. Zavodskaya laboratoriya. Diagnostika materialov. 2003. Vol. 69. pp. 35–37.
19. Tyagunov G. V., Tsepelev V. S., Tyagunov A. G., Baryshev E. E., Povodator A. M., Vyukhin V. V. Method for determining intensity of structural adjustment of melts of high-temperature alloys. Patent RF, No. 2583343. Applied: 01.04.2015. Published: 10.05.2016. Bulletin No. 13.
20. Tyagunov G. V., Tsepelev V. S., Tyagunov A. G., Baryshev E. E., Povodator A. M., Vyukhin V. V. Equipment for determination of intensity of structural change of high-temperature alloy melts. Patent RF, No. 157157. Applied: 20.05.2015. Published: 20.11.2015. Bulletin No. 32.
21. Pastukhova E. A., Vatolin N. A. et al. Difraction investigations of the structure of high-temperature melts. Ekaterinburg : UrO RAN, 2003. 334 p.