Influence of aluminium on the formation of pinholes in cast irons

• Autorzy: Elbel T. , Hampl J. , Vladik R. , Koukal R.
• Języki publikacji: EN

Abstrakty

EN

Purpose: This study concerns the formation of pinholes in castings by reaction between cast iron with compacted graphite and green sand mould. Methodology: Experiments were done on bar castings moulded in green bentonite mixtures without carbonaceous matters. Moulding sand moisture and aluminium content in the melt were purposely changed. Metal was melted in a 100 kg furnace by remelting the uniform charge of return material. Metal was inoculated all at once in a ladle and modified in a reaction chamber in a mould or as sandwich method in a pouring ladle. Findings: The formation of pinholes was not caused by high moisture of the mould but this defect was sensible to aluminium content in metal. In castings with high aluminium content > 0.2 % the pinholes occurred in high numbers, and namely under low and also high moistures [> 4 %]. In previous melts with aluminium contents < 0.02 % defects occurred in small range. Practical implications: Thus the conclusions known from literature about the influence of Al on pinholes occurrence in cast irons were confirmed. Oxygen activity in metal during its flowing and cooling in the mould was also measured but this quantity was not changed too in dependence on pinholes content. Morphological analyses near the defect have indicated that it is a physical type of pinholes caused by hydrogen. Originality: A number of works were aimed at explanation of causes of pinholes formation in lamellar graphite iron castings and spheroidal graphite ones. But this defect is formed in castings from compacted graphite cast iron too and the research was aimed just to this material. The contribution is in such a way an exceptional one.

Słowa kluczowe

EN

defect of castings; pinholes; cast iron; compacted graphite

PL

wady odlewów; otwory w żeliwie; żeliwo; grafit zagęszczony

• Wydawca: Komisja Odlewnictwa Polskiej Akademii Nauk Oddział w Katowicach
• Czasopismo: Archives of Foundry Engineering
• Rocznik: 2008
• Tom: Vol. 8, iss. 2
• Strony: 27--32
• Opis fizyczny: Bibliogr. 15 poz., rys., tab.

Twórcy

autor

Elbel T.

autor

Hampl J.

autor

Vladik R.

autor

Koukal R.

• VSB – Technical University of Ostrava, FMMI, 17. listopadu 15, 708 33 Ostrava-Poruba,

Bibliografia

• [1] J. Hampl, T. Elbel, L. Kocián, The formation of pinholes in SG iron castings. In Sborník vědeckých prací VŠB - TU Ostrava, řada hutnická, No. l, vol. IL, 2006, article No. 1271, pp. 57 - 64. ISBN 1210-0471. (in Czech).
• [2] T. Elbel, J. Hampl, R. Vladík, R. Koukal, Research of pinholes in cast irons. Technological Engineering, vol. IV, 2007, No. 1, pp. 2 - 3, ISSN 1336-5967. (In Czech).
• [3] T. Elbel, J. Hampl, R. Vladík, R. Koukal, The formation of pinholes in compacted graphite iron castings. Acta Metallurgica Slovaca 2007, vol. 13, NO. 4/2007, pp. 62 - 67. ISSN 1335-1532. (in Czech).
• [4] International atlas of casting defects. American Foundrymen´s Society, Inc. Des Plaines, 1999.
• [5] S .F. Carter et al., AFS Transactions, vol. 87, 1979, pp. 245 - 268.
• [6] S. Hasse, Guss- und Gefügefehler. Schiele & Schön, Berlin 1999.
• [7] J Baier, M. Köppen, Handbuch der Gussfehler. IKO-Erbslöh, Marl, 1994.
• [8] K. H. Rahmoeller, Mold Binder Decomposition. "Modern Casting", vol. 83, October 1993, pp. 36 - 39.
• [9] S. Katz, A New Theory for Aluminium-Induced Gas Defects in Iron Castings and Potential Solutions. AFS Transactions, vol. 114, 2006, pp. 775 - 782.
• [10] S. Fujio et al., Prevention of Pinholing in Spheroidal Graphite Iron Castings. Imono, 56, 1994, No. 4, pp. 212 - 218. (In Japan)
• [11] M. Hecht, V. Castelhano, The formation of pinholes by reaction between lamellar graphite cast iron and green sand. Fonderie-Fondeur d´aujourd´hui, Part I, No. 251, janvier 2006, pp. 12 - 32. Part II. No. 256, juin-juillet 2006, pp. 13 - 28. Part III, No. 257, aout-septembre 2006, pp. 10 - 24.
• [12] J. Zych et al., Pinholes in automotive SG iron castings using Mg treatment in-mold. In: sb. X I. Międzynarodowa konferencja WSPÓLPRACA, Zakopane 2005, pp. 195 - 204. (In Polish).
• [13] I. Riposan et al., Role of Residual Aluminium in Ductile Iron Solidification. AFS Transactions, vol. 115, 2007, 07 - 008.
• [14] Y. Kurokawa et al., Observation of Pinhole Defects in Cast Iron Castings by Surface Analysis. AFS Transactions 2002, vol. 110, pp. 629 - 637.
• [15] F. Mampaey et al., The use of oxygen activity measurement to determine optimal properties of ductile iron during production. Presented on the WFO Technical Forum, Düsseldorf, June, 13, 2007,proceedings p. 69-73.