Abstract
Porosity is a major concern in the production of light metal parts.
This work aims to identify some of the mechanisms of
microporosity formation during the gravity-poured castings of
magnesium alloy AE42. Two graphite plate molds and a ceramic
cylindrical mold were selected to produce a wide range of cooling
rates. Temperature data during cooling was acquired with type K
thermocouples at 60 Hz at two or three locations of each casting.
The microstructure of samples extracted from the regions of
measured temperature was then characterized with optical
metallography. The results of this study revealed the existence of
oxide film defects, similar to those observed in aluminum alloys.
The cooling rates showed significant effect on the formation of
porosity.
