Title: Investigation of microporosity formation mechanisms in A356 aluminium alloy castings

Authors: Arda Cetin, Ali Kalkanli

Addresses: Department of Metallurgical and Materials Engineering, Middle East Technical University, 06510, Ankara, Turkey. ' Department of Metallurgical and Materials Engineering, Middle East Technical University, 06510, Ankara, Turkey

Abstract: The problem of microporosity formation during solidification of aluminum alloy castings has great commercial importance and engineering interest due to its detrimental effects on mechanical properties. The present study concentrates on the mechanisms of microporosity formation in aluminium alloy castings. The microstructural characterisation of the produced samples was carried out with image analysis and SEM. It was observed that formation of shrinkage induced interdendritic porosity depends on solidification mode of the sample. The precipitation of intermetallic ß-Al₅FeSi platelets in the interdendritic liquid were also found to promote the interdendritic porosity formation by blocking interdendritic feeding. The results reveal that the oxide inclusions have a significant effect on formation of hydrogen precipitation induced regular micropores.

Keywords: A356 alloy; solidification; microporosity formation; image analysis; casting; aluminium alloys; microstructure; shrinkage; interdendritic porosity; hydrogen precipitation.

DOI: 10.1504/IJMMP.2009.031143

International Journal of Microstructure and Materials Properties, 2009 Vol.4 No.3, pp.377 - 385

Published online: 21 Jan 2010 *

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