Abstract
Heavy-section castings made of spheroidal graphite cast irons are known to be prone to graphite degeneracy. Upon the various degenerate forms of graphite reported in the literature, chunky graphite is the most common and detrimental one. A great deal of effort has been made for many years to prevent its formation but no convincing description of the factors controlling its appearance has been given so far.
In large-size castings, chunky graphite generally appears away from the surface and its occurrence is made evident on a metallographic section by a darker contrast. Because of this sharp and clear transition between the non-affected and the affected zones, several authors looked for chemical heterogeneities at the scale of the part but all concluded to the absence of macrosegregation.
This paper presents experimental evidence based on differential thermal analyses that metallurgical differences do exist in samples machined out of the affected and non-affected zones of a single cast block.
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References
Elliott, R., Cast Iron Technology, Butterworths (1988).
Javaid, A., Loper, C.R., “Production of Heavy-Section Ductile Cast Iron,” AFS Transactions, vol. 103, pp. 135–150 (1995).
Karsay, S.I., “Control of Graphite Structure in Heavy Ductile Iron Castings,” AFS Transactions, vol. 78, pp. 85–92 (1970).
Strizik, P., Jeglitsch, F., “Contribution to the Mechanism of Formation of Chunky Graphite,” AFS International Cast Metals Journal, vol. 1, pp. 23–30 (1976).
Liu, P.C., Li, C.L., Wu, D.H., Loper, C.R., “SEM Study of Chunky Graphite in Heavy Section Ductile Iron”, AFS Transactions, vol. 91, pp 119–126 (1983).
Asenjo, I., Lacaze, J., Larrañaga, P., Méndez, S., Sertucha, J., Suárez, R., “Microstructure Investigation of Small-Section Nodular Iron Castings with Chunky Graphite,” Key Engineering Materials, vol. 457, pp. 52–57 (2011).
Gagné, M., Labrecque, C., Javaid, A.,“Effects of Wall Thickness on the Graphite Morphology and Properties of D5-S Austenitic Ductile Iron,” AFS Transactions, vol. 115, pp. 411–421 (2007).
Gagné, M., Argo, D., “Heavy Section Ductile Iron Castings — Part I: Structure and Properties,” Proceedings of the International Conference, Advanced Casting Technology, Easwaren J. ed., ASM Int., pp. 231–256 (1987).
Källbom, R., Hamberg, K., Björkegren, L.-E., “Chunky Graphite in Ductile Iron Castings,” World Foundry Congress, paper 184 (2006).
Prinz, B., Reifferscheid, K.J., Schulze, T., Döpp, R., Schürmann, E., “Investigation of Causes of Graphite Degenerations of SG Iron like Chunky Graphite,” Giessereiforschung, vol. 43, pp. 107–115 (1991).
Mendez, S., Lopez, D., Asenjo, I., Larranaga, P., Lacaze, J., “Improved Analytical Method for Chemical Analysis of Cast Irons Application to Castings with Chunky Graphite,” ISIJ International, vol. 51, pp. 242–249 (2011).
Asenjo, I., Larrañaga, P., Sertucha, J., Suarez, R., Gomez, J.-M., Ferrer, I., Lacaze, J., “Effect of Mould Inoculation on the Formation of Chunky Graphite in Heavy-Section Spheroidal Graphite Cast Iron Parts,” International Journal of Cast Metals Research, vol. 20, pp. 319–324 (2007).
Castro, M., Herrera, M., Cisneros, M.M., Lesoult, G., Lacaze, J., “Simulation of Thermal Analysis Applied to the Description of the Solidification of Hypereutectic SG Cast Irons,” International Journal of Cast Metals Research, vol. 11, pp. 369–374 (1999).
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Lacaze, J., Asenjo, I., Méndez, S. et al. Experimental Evidence for Metallurgical Modification Associated to Chunky Graphite in Heavy-Section Ductile Iron Castings. Inter Metalcast 6, 35–42 (2012). https://doi.org/10.1007/BF03355476
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DOI: https://doi.org/10.1007/BF03355476