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Magnesium Applications
| To improve and develop commercial alloys,
products and processes to meet the application and marketing
requirements of CAST's partners and their customers |
The needs of primary magnesium producers and local
metal manufacturers drive the Magnesium Applications Sector of CAST.
A focus on technology is essential for primary magnesium producers
to survive and grow in an increasingly competitive global market
place. Magnesium suppliers must be able to offer support to their
customers in the various applications of magnesium alloys along
with innovative solutions to common manufacturing problems. In the
case of the magnesium industry such support includes the delivery
of design concepts that take advantage of the unique properties
of magnesium alloys as well as the development of advanced alloys
suited to challenging conditions. Magnesium alloys can be developed
for use in demanding operating environments such as those with elevated
temperatures.
The small size of Australia's local metal manufacturing industry
in comparison to North America and Europe can present a barrier
to the uptake of new processes and technologies. The application
of magnesium alloys is one such technology. With expertise in both
component design and casting technology, CAST is positioned to help
local industry overcome this barrier.
The Magnesium Applications Sector of CAST serves both the needs
of the primary producers (AMC, IMC) and local industry stakeholders
(represented by state governments). Through the development of new
alloys and improved processes, CAST is able to provide primary producers
with unique products. With its expertise in the design of components
and application of alloys CAST also assists in the marketing of
magnesium by core partners. At the same time these skills assist
local industry by giving them greater confidence to utilise new
materials.
Projects
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Elevated Temperature Magnesium Alloy
To develop a magnesium alloy suitable for
elevated temperature applications in terms of service performance,
cost of alloy and component manufacture.
Many conventional magnesium alloys suffer a deterioration in properties
at high temperatures preventing their use in a number of applications,
for example engine blocks. By employing a unique combination of minor
ingredients, CAST has developed a new alloy suitable for use at elevated
temperatures. This alloy is designated AMC-SC1 and is currently undergoing
testing in prototype components. This new alloy provides an opportunity
for a significant expansion in the uses of magnesium.
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Production and Processing of Wrought
Magnesium Alloys
To develop an understanding of the formability
and manufacturability of wrought magnesium alloys.
In a number of ways magnesium is considered to be similar to aluminium.
However, while, aluminium is used extensively in extruded form,
magnesium applications are confined largely to die castings. While
magnesium can be readily extruded, a major barrier is that with
current technology, extrusion speeds are considerably slower than
for aluminium. CAST is working to overcome this barrier through
the development of new alloys, new heat treatment processes and
modifications to extrusion processes. Encouraging results obtained
in laboratory tests will soon be extended to industrial scale trials.
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Design and Development of Magnesium Die Castings
To develop know-how and a body of expertise
in die casting of magnesium alloys encompassing issues related to
component design, die design, casting process parameters and properties
of magnesium castings.
CAST provides a design and prototyping service for local industry
and, during the last year, has produced a number of magnesium components
for the automotive industry. In addition to this contract work for
external organisations, a longer term development program is creating
new designs to utilise both cast and wrought magnesium in vehicle
components used to absorb energy in crash situations. Magnesium
has unique properties that make it particularly suitable for use
in automobiles, that is, it is light weight, it has high specific
stiffness in bending and has useful strain rate dependant properties
(see highlight).
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Development of a Low-cost Creep Resistant
Magnesium Alloy
To develop a magnesium alloy suitable
for moderately elevated temperature applications with little or
no cost penalty relative to common die casting alloys.
The completed development of a successful new alloy described earlier
in "Elevated Temperature Magnesium Alloy" is not the only
focus of high temperature alloy development within CAST. Research
continues on the development of alloys with little or no cost penalty
in comparison with conventional non-creep resistant alloys. The
main developments during the past year have been an improved understanding
of factors influencing castability of the identified alloys. The
focus of this research will move towards the development of alloys
for high pressure die cast applications.
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Improved Magnesium Castings for Structural Applications
To understand the factors influencing
the variability in structural properties of magnesium castings.
A comparison of various high pressure die cast magnesium samples
and also samples produced by other processes including sand casting
and thixomolding has shown that large variations in strength and
the ability to absorb deformation can be achieved within a single
alloy. This research shows the way towards better properties for
magnesium components based on improved casting processes and a firmer
knowledge base that designers can draw on when creating new components.
An examination of strain rate sensitivity shows that aluminium content
is the key to controlling strain rate behaviour. This finding suggests
beneficial ways of employing magnesium in energy absorbing structures
within vehicles (see highlight).
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Development of Protection Technologies for Magnesium Alloys
To develop low cost non-toxic environmentally
friendly corrosion resistant surface treatments and coating technologies
for magnesium alloys.
While aluminium forms a protective layer making it resistant to
corrosion, magnesium, like steel, corrodes more readily if left
exposed. Consequently there is often a need to apply protective
coatings to components. These coatings must be both inexpensive
and non-toxic for magnesium to remain a competitively priced metal.
Within CAST a research program is being undertaken to investigate
possibilities for a new corrosion protective coating that would
enable more widespread use of magnesium components in exposed applications.
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Applied Design Corrosion Research
To provide relevant data on corrosion
performance of magnesium components to assist design.
With corrosion resistance being an important issue to consider when
designing magnesium components for exterior applications, it is
essential that the CAST design team has access to reliable information
on coatings and corrosion performance. This project has reviewed
available information on existing protection technology revealing
a major shortcoming in data suitable for designers. This has stimulated
a research program in which high pressure die cast test coupons
were cast and will shortly be coated using existing commercial processes.
This program will achieve the following outcomes:
1) To rank commercial coatings and assess design assemblies for
automotive magnesium products by designing & calibrating an
experimental cyclic corrosion and mechanical testing program for
coated or uncoated, single or assembled test pieces,
2) To develop a knowledge based system to help the design of magnesium
alloy components for replacement of existing materials for automobile
components.
Work over the next year will focus on testing coatings applied to
high pressure die cast plates. It is also intended to move the project
towards closer alignment with overseas automotive research programs.
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High Pressure Die Cast Magnesium Alloy Comparison
To characterise current HPDC Mg alloys
that may be appropriate for power train applications. Standard test
sample geometries will be produced for each alloy using the same
HPDC equipment so that a genuine comparison can be made.
As CAST is developing alloys for elevated temperature applications,
so to are several groups around the world. Several new alloys are
appearing and in each case the manufacturer is able to point to
properties demonstrating their alloy's superiority. This creates
a dilemma as to which alloy to choose and is a result of the complex
nature of creep properties. The relative performance of different
alloys can change if tested under different stress or temperature
conditions, or cast using different casting parameters. This project
aims to study the properties of several alloys under a number of
different conditions to allow more reliable comparisons to be made.
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