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The Influence of Wall Thickness and Mould Temperature on Structure and Properties of Thin Wall Ductile Iron Castings

Górny M., Kawalec M., Witek G., Rejek A.

Archives of Foundry Engineering

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2019

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iss. 2

55--59

EN

The excellent property combination of thin wall ductile iron castings (TWDI), including thin wall alloyed cast iron (e.g. austenitic TWDI) has opened new horizons for cast iron to replace steel castings and forgings in many engineering applications with considerable cost benefits. TWDI is considered as a potential material for the preparation of light castings with good mechanical and utility properties, the cost of which is relatively low. In this study, unalloyed and high Ni-alloyed (25% Ni) spheroidal graphite cast iron, with an austenitic metallic matrix were investigated. The research was conducted for thin-walled iron castings with 2, 3 and 5mm wall thickness, using different mould temperature (20°C, and 160°C) to achieve various cooling rates. The metallographic examinations i.e. characteristic of graphite nodules, metallic matrix, and primary grains of austenite dendrites (in high-nickel NTWDI) and mechanical properties were investigated. The study shows that homogeneity of the casting structure of thin-walled castings varies when changing the wall thickness and mould temperature. Finally, mechanical properties of thin-walled ductile iron castings with ferritic-pearlitic and austenitic metallic matrix have been shown.

2

Effect of Heat Treatment Parameters on the Formation of ADI Microstructure with Additions of Ni, Cu, Mo

Mrzygłód B., Kowalski A., Olejarczyk-Wożenska I., Adrian H., Głowacki M., Opaliński A.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 3A

1941--1948

EN

Metallographic examinations and mechanical tests were carried out on the ductile iron with additions of Ni, Cu and Mo in as-cast state and after austempering. TTT and CCT diagrams were plotted. The heat treatment was performed in six different variants. Studies included qualitative assessment of the microstructure and testing of mechanical properties such as R0,2, Rm, A, Z, HRC, KC. An analysis of the obtained results was also presented.

PL

Przeprowadzono badania metaloznawcze żeliwa sferoidalnego z dodatkami Ni, Cu i Mo w stanie lanym i po hartowaniu izotermicznym. Opracowano wykresy CTPi i CTPc. Obróbkę cieplną wykonano w sześciu różnych wariantach. Badania metaloznawcze obejmowały ocenę jakościową mikrostruktury i pomiary właściwości mechanicznych: R0,2, Rm, A, Z, HRC, KC. Dokonano analizy uzyskanych wyników

3

Influence of molding sand on the number of grains graphite and on the rate of thin ferrite in pieces in a nodular iron ferritic matrix

Khatemi B.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 3 spec.

303--309

EN

The nodular cast irons are characterized by high mechanical properties compared to cast iron with lamellar graphite or vermicular graphite. The ductile iron has already been the subject of many studies especially since the literature is rich on them, and sources of information are different. The fact is that the mechanical properties of nodular cast iron (FGS) depend on the number of graphite grains, their roundness, the solidification rate and nature of the matrix [3]. Many studies of nodular cast irons showed that the more spherical particles of graphite, the higher the mechanical properties are high. In gray cast irons, the graphite spheroids have anticracking and give the ductile iron ductility. Note in this connection that the higher the number of graphite grains, the higher the ductile iron has better mechanical properties. In cast iron, the nature of the matrix is depending on several parameters including the cooling rate of molten metal, the thickness, shape and dimensions of parts. The faster cooling is slow over rate of ferrite is important [3, 4]. In this paper, we tested three types of sand casting: sand –based sodium silicate, furan resin and green sand on samples spherical graphite cast iron of different thickness. The objective in this article is to determine the number of grains of graphite and ferrite for each type of sand casting under the same experimental conditions including the cooling rate and chemical composition of the liquid metal.