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1
Content available The Effect of Sulphur Content on the Microstructure of Vermicular Graphite Cast Iron
Mróz M., Orłowicz A. W., Tupaj M., Lenik M., Kawiński M., Kawiński M.
Archives of Foundry Engineering
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2022
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Vol. 22, iss. 1
18--22
EN
The application of ferritic-matrix vermicular graphite cast iron in the production of fireplace fireboxes improves their thermal output, but the consumer market for these products prioritises their price. Given this consideration, this work concerns a comparison of the quality of vermicular graphite cast iron types produced from 0.025%S pig iron (a less expensive material) and 0.010%S pig iron (a more expensive material) in terms of the number and shape of vermicular graphite precipitates varying with the magnesium level in the alloy. It turned out that the vermicular graphite cast iron made with the 0.025%S pig iron demonstrated a slightly lower number of vermicular graphite precipitates. For both vermicular graphite cast iron melts, 0.028%Mg and 0.020%Mg in the alloys provided a vermicular graphite precipitate share of approx. 50% and 95%, respectively.
2
Content available Improvement of Operating Performance of a Cast-Iron Heat Exchanger by Application of a Copper Alloy Coating
Mróz M., Orłowicz A. W., Tupaj M., Jacek-Burek M., Radoń M., Kawiński M.
Archives of Foundry Engineering
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2019
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iss. 3
84--87
EN
The paper deals with possibility to improve operating performance of cast-iron heat exchangers by providing them with a copper alloy (CuTi2Cr) with the use of the flame spraying method. A test exchanger was cast of a gray cast iron with vermicular graphite in ferritic-pearlitic matrix obtained in production conditions at KAW-MET Iron Foundry with the wire method used to vermicularize the material. The test samples were two plates cast in sand molds, of which one was given a flame-sprayed CuTi2Cr coat on one side. The operating performance of such model cast-iron heat exchangers, with and without CuTi2Cr coating, was tested on a set-up for determining the heat flow rate (thermal power) transferred by the heat exchanger to environment. The obtained results indicate that the value of the heat flow rate characterizing the CuTi2Cr-coated cast-iron heat exchanger was by 10% higher compared to the flow rate of heat conveyed to environment by the heat exchanger without coating.
3
Content available Effect of Chromium on the Solidification Process and Microstructure of Vermicular Graphite Cast Iron
Gumienny G., Dondzbach M., Kacprzyk B.
Archives of Foundry Engineering
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2015
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Vol. 15, iss. 3
29--34
EN
The paper presents the results of studies of the effect of chromium concentration on the solidification process, microstructure and selected properties of cast iron with vermicular graphite. The vermicular graphite cast iron was obtained by an Inmold process. Studies covered the cast iron containing chromium in a concentration at which graphite is still able to preserve its vermicular form. The effect of chromium on the temperature of eutectic crystallization and on the temperature of the start and end of austenite transformation was discussed. The conditions under which, at a predetermined chromium concentration, the vermicular graphite cast iron of a pearlitic matrix is obtained were presented, and the limit concentration of chromium was calculated starting from which partial solidification of the cast iron in a metastable system takes place. The effect of chromium on the hardness of cast iron, microhardness of individual phases and surface fraction of carbides was disclosed.
4
Content available Effect of Cooling Rate on Microstructure of Thin-Walled Vermicular Graphite Iron Castings
Górny M., Kawalec M., Sikora G.
Archives of Foundry Engineering
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2014
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Vol. 14, iss. 1 spec.
139--142
EN
This article addresses the effect of cooling rate and of titanium additions on the microstructure of thin-walled vermicular graphite iron (TWCI) castings as determined by changing molding media, section size and Ferro Titanium. The research work was carried out on TWCI castings and reference castings of 2-5 mm and 13-mm wall thickness, respectively. Various molding materials were employed (silica sand and insulating sand ‘‘LDASC’’) to achieve different cooling rates. Thermal analysis was implemented for determinations of the actual cooling rates at the onset of solidification. This study shows that the cooling rates exhibited in the TWCI castings varies widely (70- 14oC/s) when the wall thickness is changed from 2 to 5 mm. In turn, this is accompanied by a significant variation in the vermicular graphite fraction. The resultant cooling rates were effectively reduced by applying an insulating sand in order to obtain the desired vermicular graphite shape. In addition, good agreement was found between the theoretical predictions of the solidification process and the experimental outcome. Ti additions in combination with LDASC sand molds were highly effective in promoting the development of over 80 % vermicular graphite in castings with wall thicknesses of 2 and 3 mm as evidenced by quantitative metallographic analyses.
5
Content available remote Identification of temperature changes dynamics in selected castings as a contribution to performance life improvement
Pytel A., Pysz S.
Archives of Foundry Engineering
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2010
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Vol. 10, iss. 3
179--186
EN
Parameters describing boundary conditions and dynamics of temperature changes during casting cooling in foundry moulds and the successive performance, especially as regards the massive cast elements, were discussed. Considering the specific nature of casting operation, non-standard methods of examination of the isotherms of temperature fields on the casting surface were described to determine local overheating resulting from the technological process, chemical composition, properties of the currently applied insulation materials, casting defects and/or design. Identification of these parameters can be interpolated to laboratory conditions and to the validation of virtual models subject to computer simulation. The use in simulation of genetic algorithms combined with the results of measurements under real conditions enables more precise determination of the performance parameters, including critical states of stresses present in a structure. This should allow further optimisation of the massive castings design, considering the specific nature of a manufacturing process (alloy composition included), combined with performance parameters. Measures described here are expected to contribute to the reduced casting weight and longer time of operation.
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