Influence of Processing Route on the Properties of Magnesium Alloys |
| Journal |
Solid State Phenomena (Volumes 141 - 143) |
| Volume |
Semi-Solid Processing of Alloys and Composites X |
| Edited by |
G. Hirt, A. Rassili, A. Bührig-Polaczek |
| Pages |
43-48 |
| DOI |
10.4028/www.scientific.net/SSP.141-143.43 |
| Online since |
July, 2008 |
| Authors |
Frank Hagen,
Norbert Hort,
Hajo Dieringa,
Karl Ulrich Kainer
|
| Keywords |
Creep Behaviour, High Pressure Die Casting, Magnesium Alloy, Microstructure, New Rheocasting, Porosity, Tensile Property, Thixomolding® |
| Abstract |
Magnesium alloys had gained an increasing interest in recent years due to their promising
property profile for light weight constructions. They offer drastic advantages in weight reductions in
automotive industries compared to steel or even aluminium. Therefore they can be used to decrease
the emission of green house gases as requested by the EU directive for the reduction of CO2 emissions
and moreover due to their recyclability they also help to fulfill the requirements from the EU directive
regarding the end of life of vehicles. But still there are some limitations with regard to strength,
mostly at elevated temperatures above 130 °C. To overcome these limitations alloy development as
well as process optimization has to be done for further enhancement of the range of magnesium
applications. This paper will show and discuss the property profiles of the standard magnesium alloy
AZ91D compared to the recently developed, heat resistant magnesium alloy MRI153. The alloys
have been processed using normal high pressure die casting (HPDC), New Rheocasting (NRC) and
Thixomolding® (TM). As methods of investigation tensile and creep tests have been applied. The
creep properties have been determined in the temperature range of 135-150 °C and loads of
50-85 MPa. All these trials have been accompanied by metallographic observations (light optical
metallography, SEM) and density measurements to investigate the influence of the processing routes
on microstructure and the porosity of the materials. It will be shown that the differences in the
property profile of the chosen alloys are dependent on their different chemical compositions as well
as on different microstructures that are obtained by the different processing routes. While in the case
of AZ91D, TM is showing advantages compared to HPDC for room temperature applications, the
NRC in combination with the heat resistant alloy leads to an improvement of creep rates by two
orders of magnitudes. |
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