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Structural stability of thin-walled austempered ductile iron castings

Górny Marcin, Gondek Łukasz, Angella Giuliano, Tyrała Edward, Kawalec Magdalena, Bitka Adam

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 2

art. no. e79, 2023

EN

The structural stability of ausferrite in thin-walled Austempered Ductile Iron (ADI) castings with 5 mm wall thickness is compared to a reference casting with 25 mm wall thickness. The thin-walled and reference castings were first austenitized between 850 and 925 °C, and then austempered between 250 and 380 °C. X-ray diffraction (XRD) investigations with changing temperature were performed between - 260 up to + 450 °C to investigate the change of phase fraction, lattice parameters and strain in ausferrite. The role of the austenitization temperature on structural stability and homogeneity of the investigated ADI castings has been provided. In addition, the problem of the occurrence of “blocky” high-carbon austenite that was not completely involved during austempering, has been taken into account. Finally, it has been shown that the thin-walled castings provided higher structural homogeneity and stability if compared to the reference castings.

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Influence of Structure on the Thermophisical Properties of Thin Walled Castings

Górny M., Lelito J., Kawalec M., Sikora G.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 2 spec.

23--26

EN

This study addresses the effect of the cooling rate and of titanium additions on the thermophysical parameters of thin-walled compacted graphite iron (TWCGI) castings. Various molding materials were used (silica sand and insulating sand LDASC- Low-Density Alumina-Silicate Ceramic) to achieve different cooling rates. Different titanium additions were caused by various amount of Ferro Titanium. The research work was conducted for thin-walled iron castings with a 3-mm wall thickness. The tested material represents the occurrence of graphite in the shape of flakes (C and D types, according to the ISO Standard), nodules or compacted graphite with a percent of nodularity and different shape factor. Thermal conductivity has been determined by the laser flash technique in a temperature range of 22-600°C. The results show that the cooling rates together with the titanium content largely influence the graphite morphology and finally thermal conductivity of thin walled iron castings.

3

The control of solidification kinetics of the vacuum-cast thin-wall nickel-based superalloys by changing the geometrical characteristics of the ceramic mold

Cygan R., Szeliga D., Rokicki P., Sieniawski J., Suchy J. S.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 4

21--28

EN

This paper provides an analysis of experimental research and results of investment casting process. Temperature field in a ceramic mold is one of the problems during numerical simulation. Reducing the costs of production in precision casting involves the reduction of scraps, which is one of the fundamental problems of the foundry industry. Reducing these costs is associated with optimization of precision casting technology of aircraft engines critical parts, including control of the solidification front in thin-walled castings of nickel super alloys cast in a vacuum. It is achieved by changing the geometrical characteristics of the ceramic mold. The results of the tests were used to optimize the industrial production of aircraft components in Precision Foundry of WSK Rzeszów. Temperature distribution gained in the conducted tests allowed verification and optimization of computer simulations.

4

Role of titanium in Thin Wall Vermicular Graphite Iron Castings production

Górny M., Kawalec M.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 2

25--28

EN

In this paper the effects of titanium addition in an amount up to 0.13 wt.% have been investigated to determine their effect on the microstructure and mechanical properties of Thin Wall Vermicular Graphite Iron Castings (TWVGI). The study was performed for thin-walled iron castings with 3-5 mm wall thickness and for the reference casting with 13 mm. Microstructural changes were evaluated by analyzing quantitative data sets obtained by image analyzer and also using scanning electron microscope (SEM). Metallographic examinations show that in thin-walled castings there is a significant impact of titanium addition to vermicular graphite formation. Thin-walled castings with vermicular graphite have a homogeneous structure, free of chills, and good mechanical properties. It may predispose them as a potential use as substitutes for aluminum alloy castings in diverse applications.