Volgograd State Technical University (Volgograd, Russia):

N. I. Gabelchenko, Cand. Eng., Associate Prof., Dept. “Machines and technology of casting production”
A. A. Belov, Cand. Eng., Lecturer, Dept. “Machines and technology of casting production”, e-mail: aa-belov@bk.ru
N. A. Kidalov, Dr. Eng., Prof., Head of Dept. “Machines and technology of casting production”, e-mail: mitlp@vstu.ru
S. R. Polyak, Student

M. D. Bezmogorychnyi participated in this work.

The research is devoted to development of experimental foundry pattern equipment, allowing to obtain two or more castings in a sand-loam mould; these casting are crystallized via individual cooling procedures within structurally sensitive intervals (dendrite, eutectic crystallization and recrystallization). Influence of scale factor is excluded in this case and it makes possible to obtain control and pilot castings, which have equal sizes; influence of chemical composition is excluded as well, because all castings located in a mould have common gating and feeding system. It provides the same temperature and casting speed for two or more castings in one mould with different compositions and technological properties of moulding mixtures for each of the comparing castings. Thereby, variable cooling rate, which is individual for each casting obtained in the experimental mould, remains the main factor having influence on forming of structure, mechanical and operating properties of cast metal. Possibility of investigation of rise of mechanical and operating properties of castings owing to only adjusting of cooling rate without use of alloying and modification appears in this case. Increase of the cooling rate in local temperature-time crystallization intervals is provided by blowing with cooling gases which are fed in the mould via the stand (receiver). Retarding of cooling rate occurs as a result of mould heating during thermal oxidizing destruction of exothermal carbon-containing additives which are specially introduced in the facing layer of moulding mixture. It is necessary to mention that variation of cooling rate can be conducted via the procedures which are individual for each casting located in the experimental mould. Developed and fabricated experimental foundry equipment was used for testing of the concrete cooling procedures of thin-walled castings made of grey cast iron. Pressure of cooling compressed air, which was fed during the process, and amount of exothermal carbon-containing additive, which was introduced in composition of the facing layer of moulding mixture for pilot castings were varied. As a result, the efficient cooling procedure was selected; it allowed to rise tensile strength for the pilot casting by 13 %, to improve cast iron quality (quality index) by 23 % and to increase structure dispersity of primary austenite by 21 % without introduction of alloying elements and modifiers in cast iron composition.

1. Riposan I., Stan S., Chisamera M., Neacsu L., Cojocaru A. M., Stefan E., Stan I. Control of solidification pattern of cast irons by simultaneous thermal and contraction / expansion analysis. IOP Conference Series: Materials Science and Engineering. 2019. 529(1). DOI: 10.1088/1757-899X/529/1/012016.
2. Motoyama Y., Sekiguchi S., Okane T., Yoshida M. Thermo-elastoplastic finite element analysis of warping deformation during casting of gray cast iron. Journal of Materials Processing Technology. 2020. 277. DOI: 10.1016/j.jmatprotec.2019.116454.
3. Ilyinskiy V. A., Gulevskiy V. A., Kostyleva L. V., Gabelchenko N. I., Pozharskiy A. V. The methodfor obtaining high-quality iron castings. Application 99109855/02 RF : MPK B 22 D 27/04.
Applicant and patent owner Volgorgad State Technical University. No. 99109855/02, appl. 12.05.99, publ. 03.09.93.

4. Fraś E., Górny M., López H. F. The transition from gray to white cast iron during solidification: Part III. Thermal analysis. Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science. 2005. Vol. 36. No. 11. pp. 3093-3101. DOI: 10.1007/s11661-005-0081-8.
5. Ten E. B., Kol O. A. Dependence of cast iron chill from its carbon equivalent. Steel in Translation. 2020. Vol. 50. No. 1. pp. 31-35.
6. Wang G., Chen X., Li Y., Liu Z. Effects of inoculation on the pearlitic gray cast iron with high thermal conductivity and tensile strength. Materials. 2018. Vol. 11. No. 10. DOI: 10.3390/ma11101876.
7. Neacsu E. L., Riposan I., Cojocaru A. M., Stan S., Stan I. Carbide to graphite transition control by thermal analysis in grey cast irons. Metals. 2020. Vol. 10. No. 8. pp. 1-18. DOI: 10.3390/met10080993.
8. Anisovich G. A., Zhmakin N. P. Cooling of a casting in combined mould. Moscow : Mashinostroenie. 1969. 136 p.
9. Khinchin A. S. Intensification and regulation of the processes in brittle casting moulds. Moscow : NIImash. 1975. 63 p.
10. Shevchuk S. A. Technological basis for providing high operating properties with minimal mass of basic components of machine tools made from gray iron. Dissertation … of Doctor of Technical Sciences. Moscow. 1985. 426 p.
11. Diószegi A., Diaconu V. Fourlakidis V. Prediction of volume fraction of primary austenite at solidification of lamellar graphite cast iron using thermal analyses. Journal of Thermal Analysis and Calorimetry. 2016. Vol. 124. No. 1. pp. 215-225. DOI: 10.1007/s10973-015-5158-z.
12. Lima F. F. O., Bauri L. F., Pereira H. B., Azevedo C. R. F. Effect of the cooling rate on the tensile strength of pearlitic lamellar graphite cast iron. International Journal of Cast Metals Research. 2020. Vol. 33. No. 4-5. pp. 201-217. DOI: 10.1080/13640461.2020.1822573.
13. Babushkin B. V., Rabinovich B. V. Cooling regulation in a casting mould. Liteynoe proizvodstvo. 1962. No. 11. pp. 24-27.
14. Kostyleva L. V., Ilyinskiy V. A., Gabelchenko N. I., Pozharskiy A. V., Gulevskiy V. A. Research of cooling procedures for iron castings. Liteynoe proizvodstvo. 1999. No. 2. pp. 9-11.
15. Lima F. F. O., Bauri L. F., Pereira H. B., Azevedo C. R. F. Effect of the cooling rate on the tensile strength of pearlitic lamellar graphite cast iron. International Journal of Cast Metals Research. 2020. Vol. 33. No. 4-5. pp. 201-217.
16. Mingguo X. Effect on Solidification Structure of Hypoeutectic Grey Cast Iron by Vacuum Condition in Lost Foam Casting. Proceedings of the 2015 6^th International Conference on Manufacturing Science and Engineering. 2015. pp. 1496–1500.
17. Idelchik I. E. Directory on hydraulic resistances. 2^nd edition. Moscow : Mashinostroenie. 1975. 559 p.
18. GOST 1497-84. Metals. Methods of extension testing. Moscow : Standartinform. 2008. 22 p. Introduced since 01.01.1986.
19. GOST 9012-59. Metals. Methods of Brinell hardness measurement. Moscow : Standartinform. 2007. 39 p. Introduced since 01.01.1960.
20. Sofroni L., Riposan I., Brabie V., Chisamera M. Cast iron. Bucharest, Romania: Editura Didactica si Pedagogica Publisher, (in Romanian). 1985. p. 36–49.
21. Gabelchenko N. I., Belov A. A., Kidalov N. A., Gabelchenko A. I. Improvement of mechanical properties of iron castings via adjusting of solidification rate. CIS Iron and Steel Review. 2020. Vol. 20. pp. 17-20. DOI: 10.17580/cisisr.2020.02.04.
22. Kidalov N. A., Gabelchenko N. I., Belov A. A., Savchenko A. I. Selection of exothermic carbon-containing additives for regulating the cooling mode of iron castings. Chernye metally. 2020. No. 7. pp. 23-27.
23. Pivovarskiy E. High-quality cast iron. Translated from German. Editura Didactica si Pedagogica Publisher. 1965. 650 p.