Copper-based materials for electrical purposes usually find their origin in continuous casting lines where the effectiveness of the process and the quality of the final product depends among others on the crystallization system. The paper investigates the influence of the surface quality of the crystallizer and the geometry of the cooling system on the temperature distribution throughout the copper-magnesium alloys casting process. The obtained results prove that as the contact between the crystallizer and the cooling system is worsening the temperature of the crystallizer and the cast rod increase significantly, therefore affecting the efficiency of the process

Kordaszewski, S.

Sciezor, W.

Strzepek, P.

Zasadzinska, M.

English

Hrčak - Portal of scientific journals of Croatia

606  METALURGIJA 61 (2022) 3-4, 606-608P. STRZĘPEK,  M. ZASADZIŃSKA, S. KORDASZEWSKI, W. ŚCIĘŻORGEOMETRY AND SURFACE QUALITY OF THE CRYSTALLIZATION SYSTEM AND THEIR INFLUENCE ON THE TEMPERATURES THROUGHOUT THE CONTINUOUS CASTING PROCESSES  OF COPPER-MAGNESIUM ALLOYSReceived – Primljeno: 2021-10-28Accepted – Prihvaćeno: 2022-02-10Original Scientific Paper – Izvorni znanstveni radCopper-based materials for electrical purposes usually find their origin in continuous casting lines where the effec-tiveness of the process and the quality of the final product depends among others on the crystallization system. The paper investigates the influence of the surface quality of the crystallizer and the geometry of the cooling system on the temperature distribution throughout the copper-magnesium alloys casting process. The obtained results prove that as the contact between the crystallizer and the cooling system is worsening the temperature of the crystallizer and the cast rod increase significantly, therefore affecting the efficiency of the process.Keywords: copper-magnesium alloys, continuous casting, crystallization, temperature distribution, surfaceISSN 0543-5846METABK 61(3-4) 606-608 (2022)UDC – UDK 669.3.721:621.74.04:66.065:536.5:620.191=111INTRODUCTIONThe rapid development of today’s technology cre-ates an incredibly high demand for electrical energy and therefore makes it necessary to improve the existing conductive materials. Copper being only second to sil-ver in terms of electrical conductivity with a much low-er price per kilogram is the reason why it is the crucial material used for electrical wires [1]. However, more often than it used to, the electrical conductivity needs to coexist with a high level of mechanical properties, thus making it impossible to obtain using pure materials and proves the importance of copper alloys such as copper-magnesium alloys [2 – 4]. The input material for the wire drawing process is usually obtained in the continu-ous casting line in the form of cast rods or wire rods, where the process parameters are an important factor influencing not only the casting process but also shap-ing the properties of the final product after the metal forming process. The essence of the continuous casting process itself lies in the constant supply of liquid metal to the primary cooling system where it crystallizes into the form of a cast rod. The most significant part of the casting furnace is the crystallization system made of a crystallizer responsible for the heat transfer to the cool-ing system [5, 6]. The effectiveness of the process should depend solely on the characteristics of the mate-rial used for the cooling system, its geometry and qual-ity of contact between the cooling system and the crys-tallizer [7 - 9].EXPERIMENTAL PROCEDUREThe conducted study took into consideration the laboratory continuous casting furnace presented sche-matically at Figure 1, where all the vital parts of the furnace have been marked. However, the study focuses on the crystallization system, which consists of the crystallizer and the cooling system which were present-ed up close at Figure 2. Research conducted with the FLUENT module of the ANSYS software determined the cast rod temperature and cooling medium tempera-ture after exiting the crystallization system. Additional-ly the temperature distribution of the crystallizer was determined in the form of temperature mapping. The set constant conditions were as follows, the temperature of the liquid metal 1200 °C, the cast rod diameter 14 mm, the casting feed 0,1 m/min. The variables were centred around the crystallization system i.e. surface roughness of the crystallizer, material used for the manufacturing of the cooling system and the shape of the cooling sys-tem’s internal canals. P. Strzępek (e-mail: strzepek@agh.edu.pl), M. Zasadzińska, S. Kor-daszewski, W. Ściężor, AGH University of Science and Technology, Faculty of Non-Ferrous Metals, Cracow, PolandFigure 1  The schematics of the laboratory continuous casting furnace607P. STRZ PE  et al.: GEOMETRY AND SUR A E UALITY O  T E RYSTALLIZATION SYSTEMMETALURGIJA 61 (2022) 3-4, 606-608RESULTS AND DISCUSSIONThe variables applied for the simulations of the con-tinuous casting process were carefully selected in order to determine the influence of the surface roughness of the crystallizer (Ra 0,63 µm and 1,25 μm) at the place of contact with the cooling system, the geometry of the internal canals of the cooling system (empty cooling system, cooling system with two division walls and spi-ral cooling system) and finally the material used for the manufacturing of the cooling system (copper and steel). Figure 2  The model used for the continuous casting process finite element method simulations; A – primary cooling system; B – crystallizerFigure 3  Empty cooling system made of Cu and graphite crystallizer with Ra 1,25 / °CFigure 4  Empty cooling system made of steel and graphite crystallizer with Ra 1,25 / °CFigure 5  Two divisions cooling system made of Cu and graphite crystallizer with Ra 1,25 / °CFigure 6  Two divisions cooling system made of Cu and graphite crystallizer with Ra 0,63 / °CFigure 7  Two divisions cooling system made of steel and graphite crystallizer with Ra 1,25 / °CFigure 8  Spiral cooling system made of Cu and graphite crystallizer with Ra 1,25 / °CFigure 9  Spiral cooling system made of Cu and graphite crystallizer with Ra 0,63 / °CFigure 10  Spiral cooling system made of steel and graphite crystallizer with Ra 1,25 / °CThe obtained results were presented at Figures 3 – 10 and collective data regarding the registered tempera-tures were put together in Table 1. The data represent the temperature of the cast rod and the cooling medium 608  METALURGIJA 61 (2022) 3-4, 606-608P. STRZ PE  et al.: GEOMETRY AND SUR A E UALITY O  T E RYSTALLIZATION SYSTEMtemperature after exiting the cooling system. The im-portant factor that needs to be understood is that the reg-istered cooling medium temperatures are closely related to the heat transfer between the crystallizing material through the crystallizer to the cooling system, therefore the higher the cooling medium temperature the better the heat transfer. On the other hand the better the heat transfer the lower the temperature of the obtained cast rods and this is what the continuous casting industry is looking for in a nutshell, as by lowering the prospective temperatures of the crystallizer and the cast rod the feed may be increased, thus increasing the production rate.The proposed temperatures were quantified as with constant values of the other parameters of the process they remain a solid measure of the heat transfer at the continuous casting crystallization system. As presented at the collective Table 1 it is clearly visible that regardless of the geometry of the cooling system copper based ma-terial corresponds with a much better heat transfer than steel cooling system. The differences in the obtained tem-peratures for the tested parameters reach over a 100 °C in favour of copper cooling system. When considering the geometry the differences are not that vital, however, the application of two division walls or a spiral division in-side of the cooling system instead of the no division at all shows that it has an impact on the process temperatures. What is of much importance for the industrial processes is that by lowering the surface roughness of the crystal-lizer at the place of contact with the cooling system the registered temperatures of the cast rod were drastically lower. Bearing that in mind it may be stated that by sim-ply polishing the contact surface of the graphite crystal-lizer the process may by conducted at higher feed veloc-ity, therefore increasing the production rate. Based on the tested parameters, constants and variables it has been proven that the copper cooling system with a spiral inter-nal canal system and a graphite crystallizer with surface roughness Ra 0,63 at the place of contact with the cooling system provides the best heat transfer and therefore the lowest temperature of the cast rod.CONCLUSIONSOn the basis of the conducted research it may be stated that:Even though the price of copper is higher than steel the registered temperatures of the process decrease sig-nificantly when copper cooling system is being applied, therefore making it a much desirable choice.Construction of the cooling system should account for using kind of a division wall instead of an internally emp-ty system as by directing the cooling medium flow the obtained temperatures of the cast rod are visibly lower.Improving the surface quality of the graphite crys-tallizer at the place of contact with the cooling system significantly increases the heat transfer therefore lower-ing the registered temperatures of the obtained cast rod.The conducted research discusses the copper-mag-nesium alloys, however, it may be easily adapted to other copper alloys or pure copper obtained in the con-tinuous casting lines.AcknowledgementsAuthors are grateful for the financial support of this research provided by The National Centre for Research and Development – Research Project No. LIDER/ 33/0121/L-11/19/NCBR/2020.REFERENCES[1]  J. Chen, W. Yan, W. Li, J. Miao, X. H. Fan, Texture evolu-tion and its simulation of cold drawing copper wires pro-duced by continuous casting, Transactions of Nonferrous Metals Society of China 21 (2011), 152 – 158.[2]  P. Strzępek, A. Mamala, M. Zasadzińska, P. Noga, M. Sadzikowski, The influence of the continuous casting con-ditions on the properties of high-strength two-phase CuMg alloys, Materials no. 13 (2020) art. no. 4805 p. 1-11.[3]  Y. Ito, H. Matsunaga, H. Mori, K. Maki, Effect of Plastic Deformation on the Proof Strength and Electrical Conducti-vity of Copper-Magnesium Supersaturated Solid-Solution Alloys, Materials Transactions 55 (2014), 1738–1741.[4]  G. Liu, S. Jia, S. Hong, J. Lim, Y. Zhu, K. Mimura, M. Isshiki, Corrosion resistance of dilute CuMg alloys at ele-vated temperature. Corrosion Science 51 (2009), 463–468.[5] M. Zasadzińska, T. Knych, B. Smyrak, P. Strzępek, Inve-stigation of the dendritic structure influence on the electri-cal and mechanical properties diversification of the conti-nuously casted copper strand, Materials 13 (2020) art. no. 5513 p. 1-13.[6] S. Kianfar, S. H. Seyedein, M. R. Aboutalebi, Heat transfer and solidification analysis in the mould region of a ho ri-zontal copper alloy billet continuous caster, International Journal of Cast Metals Research 22(1-4) (2009), 160 – 163.[7] P. Kwaśniewski, P. Strzępek, G. Kiesiewicz, et al., Exter-nal surface quality of the graphite crystallizer as a factor influencing the temperature of the continuous casting pro-cess of ETP grade copper, Materials 14 (2021) art. no. 6309 p. 1-14.[8] Y. Han, X. B. Zhang, E. Yu, L. Sun, Y. Gao, Numerical analysis of temperature field and structure field in horizontal continuous casting process for copper pipes, International Journal of Heat and Mass Transfer 115 (2017), 294 – 306.[9]  D. C. Tsai, W. S. Hwang, Numerical simulation of the soli-dification processes of copper during vacuum continuous casting, Journal of Crystal Growth 343 (2012), 45 – 54.Note:  The translator responsible for English language: Andrzej Mamala, AGH University of Science and Technology, Kraków, PolandTable 1  Collective data of the registered temperatures of the cast rod and water after exiting the cooling system / °CEmpty cooling system Two division walls cooling system Spiral cooling systemCopper - graphite  (Ra 1,25)Steel - graphite  (Ra 1,25)Copper - graphite  (Ra 1,25)Copper - graphite (Ra 0,63)Steel - graphite (Ra 1,25)Copper - graphite (Ra 1,25)Copper - graphite (Ra 0,63)Steel - graphite (Ra 1,25)Cooling medium temperature  at measuring point56,12 45,76 59,84 63,60 49,66 61,40 64,96 49,35Cast rod temperature at measur-ing point541,36 654,13 507,97 461,29 606,45 501,02 452,06 628,77

Geometry and surface quality of the crystallization system and their influence on the temperatures throughout the continuous casting processes of copper-magnesium alloys

Geometry and surface quality of the crystallization system and their influence on the temperatures throughout the continuous casting processes of copper-magnesium alloys

Abstract

Similar works

Full text

Available Versions

Hrčak - Portal of scientific journals of Croatia