ISSUE 3/2009

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Markus Ostermeier, Michaela Brummer, Ewald Werner, Munich, Germany
Hot isostatic pressing of magnesium castings

Hot isostatic pressing (HIP) is a process employed to remove porosity in castings and improve their mechanical properties. This is achieved by exposing the work piece to both high temperature and high isostatic pressure over an appropriate time period. A number of studies are available about the practice of HIP used in aluminium alloy casting. However, HIP used on magnesium alloys has yet to be explored in depth. Therefore a research project was carried out systematically subjecting sand and pressure die cast MgAl9Zn1 (AZ91) specimens to HIP. It was demonstrated that the application of HIP significantly improves the mechanical properties of both types of castings, the improvement being more obvious in sand castings. However, high porosity as present in pressure die castings leads to highly scattered results. Therefore not all of the observed trends could be verified by statistical evaluations.

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