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Abstract

The new investigation method of a permeability of ceramic moulds applied in the investment casting technology, is presented in the paper. Some concepts of performing permeability measurements are shown. Investigations in which the influence of the solid phase fraction in the liquid ceramic moulding sand (LCMS) on a permeability of a multi-layer ceramic mould were performed and discussed. The permeability was estimated during two the most important stages of the technological process: in the first – after wax melting and in the second – after mould annealing. Also an influence of the matrix grain sizes (material for sprinkling) on a ceramic mould permeability was estimated.
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Authors and Affiliations

J. Zych
J. Kolczyk
T. Snopkiewicz
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Abstract

The results of testing of the selected group of wax mixtures used in the investment casting technology, are presented in the paper. The measurements of the kinetics of the mixtures shrinkage and changes of viscous-plastic properties as a temperature function were performed. The temperature influence on bending strength of wax mixtures was determined.
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Authors and Affiliations

J. Zych
J. Kolczyk
T. Snopkiewicz
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Abstract

Cast iron destined for spheroidization is usually characterized by a near-eutectic chemical composition, which is a result of the necessity of maintaining its high graphitizing ability. This graphitizing ability depends mainly on the chemical composition but also on the so-called physical-chemical state. This, in turn, depends on the melting process history and the charge structure. It happens quite often, that at very similar chemical compositions cast irons are characterized by different graphitizing abilities. The hereby work concerns searching for the best method of assessing the graphitizing abilities of near-eutectic cast iron. The assessment of the graphitizing ability was performed for cast iron obtained from the metal charge consisting of 100% of special pig iron and for synthetic cast iron obtained from the charge containing 50% of pig iron + 50% of steel. This assessment was carried out by a few methods: wedge tests, thermal analysis, microstructure tests as well as by the new ultrasonic method. The last method is the most sensitive and accurate. On the basis of the distribution of the wave velocity, determined in the rod which one end was cast on the metal plate, it is possible to determine the graphitizing ability of cast iron. The more uniform structure in the rod, in which directional solidification was forced and which had graphite precipitates on the whole length, the higher graphitizing ability of cast iron. The homogeneity of the structure is determined by the indirect ultrasonic method, by measurements of the wave velocity. This new ultrasonic method of assessing the graphitizing ability of cast iron of a high Sc (degree of eutectiveness) and CE (carbon equivalent) content, can be counted among fast technological methods, allowing to assess the cast iron quality during the melting process.
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Bibliography

[1] Janerka, K. (2010). Carburizing of iron alloys. Gliwice: Wydawnictwa Politechniki Śląskiej. (in Polish).
[2] Janerka, K. (2019). The rate effectiveness of carbonization to the sort of carburizer. Archives of Foundry Engineering. 7(4), 95-100.
[3] Karsay, S.J. (1992). Ductile Iron I, Production. Canada: QIT –Fer & Titane.
[4] Fraś, E., Podrzucki, Cz. (1981). Modified cast iron. Kraków: Skrypt AGH. (in Polish).
[5] Riposan, I., Chisamera, M., Stan, S., Adam, N. (2004). Influencing Factors on the High Purity - Steel Scrap Optimum Ratio in Ductile Iron Production. Ductile Iron News. 2, 10-19.
[6] Riposan, I., Chisamera, M., Stan, S., Constantin, V., Adam, N. & Barstow, M. (2006). Beneficial remnant effect of high purity pig iron in industrial production of ductile iron. AFS Transactions. 114, 657-666.
[7] Fraś, E. (1978). Przegląd Odlewnictwa. 6,133. (in Polish).
[8] Podrzucki, Cz. (1991). Cast iron - structure - properties – application. Kraków: Wyd. ZG STOP. (in Polish).
[9] Podrzucki, Cz., Falęcki, Z., Wiśniewski, B. (1966). Przegląd Odlewnictwa. 7-8, 248. (in Polish).
[10] ASTM Standards of iron casting, (1957). Tentative methods of testing of cast iron. 76, A 367-55T.
[11] Podrzucki Cz., Kalata Cz. (1976). Metallurgy and iron founding. Katowice: Wyd. Śląsk. (in Polish).
[12] Zych ,J. (2000). The study of the sensitivity of cast iron to the cooling rate using the ultrasonic method. Solidification of Metals and Alloys. 43, 543-552. (in Polish).
[13] Zych, J. (2001). Multi-stage, ultrasonic control of the ductile iron castings production process. Archives of Foundry. 1(1/2), 227-235. (in Polish).
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Authors and Affiliations

J. Zych
1
ORCID: ORCID
M. Myszka
1
T. Snopkiewicz
1

  1. AGH University of Science and Technology, Faculty of Foundry Engineering, Department of Moulding Materials, Mould Technology and Cast Non-Ferrous Metals, Al. Mickiewicza 30, 30-059 Kraków, Poland
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Abstract

This paper presents a new stand for studying the linear shrinkage kinetics of foundry alloys. The stand is equipped with a laser displacement sensor. Thanks to this arrangement, the measurement is of a contactless nature. This solution allows for the elimination of errors which occur in measurements made using intermediary elements (steel rods). The supposition of the expansion (shrinkage) of the sample and the expansion of the heated rod lead to the distortion of the image of the actual dimensional changes of the studied sample. A series of studies of foundry alloys conducted using the new stand allowed a new image of shrinkage kinetics to be obtained, in particular regarding cast iron. The authors introduce in the study methodology a real-time measurement of two linked quantities; shrinkage (the displacement of the free end of the sample) and temperature in the surface layer of the sample casting. This generates not only a classic image of shrinkage (S) understood as S = f (t), but also the view S = f (T). The latter correlation, developed based on results obtained using the contactless method, provide a new, so far poorly known image of the course of shrinkage in foundry alloys, especially cast iron with graphite in the structure. The study made use of hypo- and hypereutectic cast iron in order to generate an image of the differences which occur in the kinetics of shrinkage (as well as in pre-shrinkage expansion - expansion occurs during solidification).

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Authors and Affiliations

J. Zych
ORCID: ORCID
T. Snopkiewicz
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Abstract

Two standardised grades of spheroidal cast iron determined in standard EN PN 1563 – 1997 as: EN-GJS-350 – 22LT (T = –40°C) and EN GJS 400 – 18LT (T = –20°C) are intended for work at low temperatures: –20 and –40oC. The main mechanical property of these cast iron grades is a high impact strength at a work temperature down to: –40°C. A series of controlled melts was performed to optimise the production technology of spheroidal cast iron, which in as-cast state is characterised by ferritic matrix (the best without any pearlite), fine precipitates of nodular graphite and high purity (without non-metallic inclusions). Variable structures of metal charges and various spheroidisation techniques (the modification methods) (slender ladle with a tight cover – Tundish technology as well as the technology with cored wire) were applied in the research. In order to obtain refinement of graphite precipitates and to achieve the ferritic matrix multistage inoculations of technologies were applied. Cast iron was subjected to refining to limit non-metallic inclusions since they decrease the impact strength. The production process of cast iron was controlled by the thermal derivative analysis at the stage of initial cast iron and after its secondary metallurgy (modification and inoculation). It was pointed out, that the reproducible production of cast iron for work at low temperatures was only possible when all elements of the technological process were strictly adhered to. It was pointed out, in the hereby paper, that: it should be strived to maintain Si content not higher than 2.50÷2.60%, which at producing spheroidal cast iron is sometimes difficult and requires using a lot of pig iron in the metal charge. For a fast assessment of the cast iron quality, concerning its impact strength, the proposed – in the hereby paper – index quality (IQu) can be applied. It is determined on the bases of measuring the cast iron hardness and propagation velocity of ultrasound wave.
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Authors and Affiliations

J. Zych
1
ORCID: ORCID
T. Jurga
2
J. Mocek
1
M. Myszka
1
T. Snopkiewicz
1

  1. AGH University of Science and Technology, Faculty of Foundry Engineering, Al. Mickiewicza 30, 30-059 Kraków, Poland
  2. Odlewnia Żeliwa Drawski S.A, Drawski Młyn, Poland

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