Grain size refinement through gas bubble stirring in AC4CH cast aluminium alloy

Nasir Hayat, Toshiro Kobayashi, Hiroyuki Toda, Hirotsugu Kojima

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Abstract

A comparison has been made of the mechanical properties of gravity and squeeze cast aluminium alloys that have been grain refined using gas bubbling and those that have not. To find the optimum gas bubbling conditions, the alloy melt temperature, the gas flow rate and the gas bubbling times were varied over wide ranges. The microstructure of the gas bubbled gravity and squeeze cast materials is fine, equiaxed and non-dendritic with an average primary α size of 52 μm and 163 μm respectively. However, gas bubbling has no effect on the morphology of the eutectic Si. There seems to be no noticeable difference between the measured mechanical properties of the gravity and squeeze cast materials with or without the gas bubbling. The lack of improvement in the mechanical properties of the gravity cast alloy is due to casting defects and porosity, which offset the effects of the grain refinement. The crystal separation and showering mechanisms are operative for the formation of equiaxed grains.

Original languageEnglish
Pages (from-to)505-512
Number of pages8
JournalInternational Journal of Cast Metals Research
Volume15
Issue number5
DOIs
Publication statusPublished - Jan 1 2003
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys

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