The modifying possibility of the commercial CuZn37 brass (M63) with nickel and silicon is being discussed throughout the article. The proposed alloy additives made it possible to improve the commercial brass properties by precipitation hardening, thus making it extremely competitive in comparison to base material. The study also discussed the conditions (temperature and time) of the metallurgical synthesis and its influence on the weight percentage of not only proposed alloy additives but also the amount of zinc loss from the commercial brass due to the evaporation during the metallurgical processes

Franczak, K.

Kiesiewicz, G.

Kordaszewski, S.

Kowal, R.

Kwasniewski, P.

Sciezor, W.

Strzepek, P.

English

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619METALURGIJA 61 (2022) 3-4, 619-621S. KORDASZEWSKI, P. KWAŚNIEWSKI, G. KIESIEWICZ, K. FRANCZAK,  W. ŚCIĘŻOR, R. KOWAL, P. STRZĘPEK OPTIMALIZATION OF THE METALLURGICAL SYNTHESIS PARAMETERS OF CUZN37 BRASS WITH NICKEL AND SILICON ALLOY ADDITIVESReceived – Primljeno: 2021-10-22Accepted – Prihvaćeno: 2022-03-03Original Scientific Paper – Izvorni znanstveni radThe modifying possibility of the commercial CuZn37 brass (M63) with nickel and silicon is being discussed through-out the article. The proposed alloy additives made it possible to improve the commercial brass properties by pre-cipitation hardening, thus making it extremely competitive in comparison to base material. The study also discussed the conditions (temperature and time) of the metallurgical synthesis and its influence on the weight percentage of not only proposed alloy additives but also the amount of zinc loss from the commercial brass due to the evapora-tion during the metallurgical processes.Keywords: CuZn37-Ni-Si alloy, metallurgical synthesis, heat treatment, hardness parameters, electrical conductivityISSN 0543-5846METABK 61(3-4) 619-621 (2022)UDC – UDK 669.35.5.24.782:669-66.091:66.04:620.178.1:537.311.3=111INTRODUCTIONThe alloys of copper and zinc (commonly known as brasses) were the search result for the substitute alloys for tin bronzes and lead bronzes as the former suffer from the deficit of the main alloy additive and the use of the latter became limited due to the guidelines of EU directive regarding the restriction of the use of hazard-ous substances [1,2].The typical zinc addition to copper ranges from 10 and 50 wt. % as higher content makes causes brittleness in brasses. The addition of zinc has a significant impact on the technological, mechanical, electrical and physi-cal properties of the discussed alloys (see Figure 1) [3].Depending on the used alloy additives the strength properties of brasses (Rm) may vary from 250 to even 750 MPa and electrical conductivity ranges from 3 to 15,6 MS/m. Selected brass grades commonly used in everyday industry along with mechanical and electrical properties were presented collectively in Table 1.Table 1  Properties of selected, typical brass grades [3-10]Alloy Rm / MPa R0,2 / MPa A / % γ / MS/mCuZn37 275-600 70-550 10-30 13,0-15,6CuZn39Pb2 250-560 120-510 12-15 13,9-15,5CuZn28Sn 365-669 124-496 4-69 14,5CuZn16Si4(MK80)400-500 230-300 8-30 3-6EXPERIMENTAL PROCEDUREThe charge material for the conducted research was CuZn37 (M63) in the form of qualified scrap. Generally the alloy in question does not respond to heat treatment, however, based on the accessible literature it is postu-lated that the addition of nickel and silicon to CuZn37 forms a new alloy with prospective precipitation hard-ening possibilities as the brass-based material with nu-merous precipitation of Ni2Si (Figure 2) [11-13]. The Cu-Ni2Si phase diagram presented at Figure 3 suggests that the appropriate Ni and Si content in Cu creates ma-terial susceptible to heat treatment.S. Kordaszewski (e-mail: szyk@agh.edu.pl), P. Kwaśniewski, G. Kie-siewicz, K. Franczak, W. Ściężor, R Kowal, P. Strzępek, University of Science and Technology, Faculty of Non-Ferrous Metals, Cracow, Po-landFigure 1  Rm / MPa and elongation A / % of brass in the function of zinc content / wt. % [1]Figure 2  The concept of CuZn37 with the alloy additives of Ni and Si620  METALURGIJA 61 (2022) 3-4, 619-621S. KORDASZEWSKI et al.: OPTIMALIZATION OF THE METALLURGICAL SYNTHESIS PARAMETERS OF CUZN37 BRASS...Initial heat treatment researchInitial research works on the possibility of introduc-ing alloy additives of Ni and Si to CuZn37 brass and therefore obtaining a new alloy susceptible to heat treat-ment were conducted. CuZn37 brass scrap material with a defined chemical composition in compliance with EN-1982:2017 standard, pure nickel with mini-mum of 99,95 wt. % of Ni and pure silicon with mini-mum of 99,5 wt. % of Si, both in compliance with prop-er standards. Metallurgical synthesis of CuZn37 brass with alloy additives was conducted in a graphite cruci-ble as it has been proven not  to be wettable by copper and copper alloys [14]. The process was carried out in a resistance furnace at 1 200 °C temperature for 1,5 hour, thus obtaining materials with chemical compositions as presented in Table 2. Each of the obtained materials was subjected to further homogenization and supersatura-tion process followed by artificial aging. The parame-ters of the metallurgical synthesis and heat treatment were collectively presented in Table 3.Each of the research stages presented in Table 3 were followed by electrical conductivity and hardness tests. Electrical conductivity was determined with using eddy current method on SigmaTest 2.069 device with the measuring range of 0,5 MS/m and 65 MS/m (i.e. from 1 % to 112 % IACS), the accuracy of +/- 0,5 % and the resolution of +/- 0,1 % at 60 kHz. Vickers hardness was determined using Tukon2500 device with the load range of 10 gf to 50 kgf, a force measurement error of +/- 1,5 % below 200 g and +/- 1 % above 200 g. The research was conducted with 10 kgf and load time of 10 s.Research on the metallurgical synthesis parameters – zinc evaporationThe first stage of the research was focused on the zinc evaporation during metallurgical synthesis pro-cesses (melting and alloying). Initially research was conducted on CuZn37 brass scrap which was held in the liquid state in 1 100 °C, 1 150 °C and 1 200 °C for 2 hours. Further research included materials with Ni (1 wt. %) and Si (0,5 wt. %). Extensive research with target alloy were conducted with a wider range of tem-peratures (1 050 °C – 1 200 °C every 50 °C) and be-tween 0,5 h and 2 h every 0,5 h.Research on the metallurgical synthesis parameters – alloying of Ni and SiThe research on the target alloy (CuZn37 with Ni and Si alloy additives) was conducted in analogical conditions in terms of temperature and time as described above. The aim of the research was determination of the favourable metallurgical synthesis parameters that would allow obtaining of the intended values of Ni (1 wt. %) and Si (0,5 wt. %) in CuZn37 alloy. RESULTS AND DISCUSSION Initial heat treatment researchThe obtained results presented at Figure 4 confirmed that neither CuZn37 with only Ni nor CuZn37 with only Si may be subjected to precipitation hardening. However, it was proven that when both alloy addi-tives are added to CuZn37 the obtained alloy shows the effect of precipitation hardening as a result of heat treat-ment. After only 1 hour of artificial aging the hardness of the obtained CuZn37Ni1Si0,5 alloy increases from ap-prox. 110 HV10 to approx. 126 HV10 with simultaneous increase of the electrical conductivity from approx. 11,8 MS/m to approx. 12,5 MS/m which indicates that Ni2Si phase have precipitated from the solid solution.Zinc evaporationThe research on zinc evaporation proved that when the temperature of furnace was set to 1 200 °C only when the liquid metal was exposed to high temperature for 0,5 h it did not exceed the zinc evaporation of 2 wt. % which is a generally accepted standard. For 1 150 °C Figure 3 Cu-Ni2Si phase diagram [10, 11]Table 2 Chemical composition of the obtained alloys / wt. %Alloy Cu Zn Ni Si OtherCuZn37 63,14 36,78 00,1 0,00258 0,07364CuZn37Si0,562,52 36,9 0,01 0,5136 0,0564CuZn37Ni0,561,67 37,75 0,4707 0,0398 0,0695CuZn37Ni0,5Si0,561,92 37,12 0,4546 0,4322 0,0732Table 3  Parameters of the metallurgical synthesis and heat treatmentResearch stage Time TemperatureMetallurgical synthesis 1,5 h 1 200 °CQuenching 5 h 700 °CArticial aging 1 h 400 °C3 h 400 °C5 h 400 °CFigure 4  The heat treatment influence on the electrical conductivity and Vickers hardness of the obtained alloys621S. KORDASZEWSKI et al.: OPTIMALIZATION OF THE METALLURGICAL SYNTHESIS PARAMETERS OF CUZN37 BRASS...METALURGIJA 61 (2022) 3-4, 619-621the time could be increased to 1 h and with lower tem-peratures none of the tested times exceeded the 2 wt. % limit of zinc evaporation. Out of the 16 variants of time and temperature 2 wt. % of zinc evaporation was not exceeded for 11 of them – Figure 5.Research on metallurgical synthesisA wide range of time and temperature variants of metallurgical synthesis and their influence on the wt. % content of Ni and Si in the CuZn37Ni1Si0,5 alloy was presented collectively in Table 4. Table 4  Obtained contents of Ni and Si  in the CuZn37 alloy / wt. %TimeTemp.0,5 h 1 h 1,5 h 2 h Alloy ad-ditive1 050 °C 0,530,360,820,300,84 0,390,840,34NiSi1 100 °C 0,660,370,860,420,890,380,910,43NiSi1 150 °C 0,930,380,910,420,970,451,010,45NiSi1 200 °C 0,920,400,940,451,040,481,120,50NiSiOut of the 16 variants of metallurgical synthesis only 5 fulfilled the expected amount of Ni (expected at least 0,95 wt. % of Ni) and Si (expected at least 0,45 wt. % of Si). These were the temperature of 1 200 °C with the metallurgical synthesis times of 1, 1,5 and 2 hours and for 1 150 °C with the metallurgical synthesis times of 1,5 and 2 hours. These are, however, the times and temperatures where the evaporation of zinc exceeded the standardized 2 wt. % of loss.CONCLUSIONSOn the basis of the conducted research it may be stated that:Simultaneous addition of Ni and Si to the commer-cial brass alloy CuZn37 (M63) allows the obtaining of the entirely new alloy which properties may be im-proved with the heat treatment and activating precipita-tion hardening.Further research was devoted to defining of the opti-mal parameters of the metallurgical synthesis of CuZn37 brass alloy with alloy additives of Ni and Si carried out in the resistance furnace. Zinc evaporation is a substan-tial, serious and inevitable issue. Obtaining brass alloy with simultaneously expected wt. % of Ni and Si alloy additives requires the process to be conducted either high temperature or long time of the synthesis which results in significant zinc evaporation and as such re-quires for a compromise to be made. As the main objec-tive is to obtain a desired chemical composition with possibility of alloying additional zinc lost due to evapo-ration the guidelines for the metallurgical synthesis pa-rameters  using resistance furnace were defined at 1 150 °C with 1,5 hour of alloying time.The conducted study provides basic knowledge for prospective further research aimed at developing of a new brass-based alloy with an optimal range of Ni and Si alloy additives along with the selection of the heat treatment parameters of the said alloys.REFERENCES[1] N. Ninan, S.V.S. N. Murty, S. Manwatkar, P. R. Narayanan, Failure analysis of cracked brass turrets used in electronic circuits, Engineering Failure Analysis 2 (2014) 107-117 [2] F. Schultheiss, D. Johansson, V. Bushlya, J. Zhou, K. Nils-son, J.-E. Ståhl , Comparative study on the machinability of lead-free brass, Journal of Cleaner Production (2017) 149 C 366-377[3] L. Dobrzański, Podstawy nauki o materiałach i meta-loznawstwo, 2002[4] Standard PN-EN 1652:1997 – Miedź i stopy miedzi: Płyty, blachy, taśmy i krążki ogólnego przeznaczenia[5] Standard EN 12166 Copper and copper alloys: Wire for general purposes[6] Standard PN-EN 12167 (E) Miedź i stopy miedzi: Kształtowniki i pręty prostokątne ogólnego przeznaczenia”[7] P. Strzępek, A. Mamala, M. Zasadzińska, K. Franczak, B. Jurkiewicz, Research on the drawing process of Cu and CuZn wires obtained in the cryogenic conditions, Cryoge-nics 100 (2019), 11-17[8] J. R. Davis, Copper and copper alloys, ASTN International Handbook Committee, 2001.[9] Standard EN-1982:2017 (E): Miedź i stopy miedzi[10] Standard EN 12166 Copper and copper alloys: Wire for general purposes [11] A. Bögel, TEM-Untersuchungen an höherfesten und elektrisch hochleitfähigen CuNi2Si-Legierungen, Metall-Forschung 63, (2009)[12] P.  Kwaśniewski, Nośno-przewodzący osprzęt górnej ko-lejowej sieci trakcyjnej, Materiały – Konstrukcje - Techno-logie Wytwarzania (2016) [13] W. Gluchowski, Z. Rdzawski, J. Sobota, J. Domagala-Du-biel, Effect of the combined heat treatment and severe plastc deformation on the microstructure of CuNiSi alloy, Archi-ves of metallurgy and materials  61 2 (2016)  1207-1214[14] M. Poręba, T. Kubaszek, M. Góral, B. Koscielniak, K. Gancarczyk, M. Drajewicz, The Formation of Columnar YSZ Ceramic Layer on Graphite by PS-PVD Method for Metallurgical Applications, Solid State Phenomena 320 (2021), 49-54Note:  The translator responsible for English language: Andrzej Mamala, AGH University of Science and Technology, Kraków, PolandFigure 5 Zinc evaporation due to metallurgical synthesis processes

Optimalization of the metallurgical synthesis parameters of CuZn37 brass with nickel and silicon alloy additives

Optimalization of the metallurgical synthesis parameters of CuZn37 brass with nickel and silicon alloy additives

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