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87Fraunhofer Institute for Laser Technology ILT, www.ilt.fraunhofer.de
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3 Typical application, source: MEV.
4 Long-exposure image of illuminated
powder layer during SLM.
approaching 100 percent. The next step is to study the
mechanical properties. Initial results indicate that very high
strengths can be achieved (Rm and Rp 0.2 approx. 500 MPa),
accompanied by high elongations at rupture (A approx.
20 percent). Compared with SLM components made of
AlSi10Mg, the yield strength Rp 0.2 is approx. 200 percent
higher and the elongation at rupture approx. 400 percent
higher. Aerospace components are frequently subjected
to dynamic loads, which are currently being tested in an
exhaustive series of fatigue tests. Initial results indicate that
test specimens made of AlMgScZr possess greater dynamic
strength than components made of AlSi10Mg.
In future studies, we aim to determine whether it is possible
to increase component strength still further by increasing
the Sc or Mg content of the alloy and by increasing the SLM
process cooling rate. Other potential means of reducing
component weight include optimizing component topology
and its manufacture by SLM.
contacts
Dipl. -Ing. Damien Buchbinder
Phone +49 241 8906-488
Dr. Konrad Wissenbach
Phone +49 241 8906-147
task
Two die-casting alloys, AlSi10Mg and AlSi9Cu3, have already
been qualified at Fraunhofer ILT for the additive manufacturing
of aluminum components by Selective Laser Melting (SLM).
The aerospace industry has a need for high-strength aluminum
components that are suitable for lightweight construction and
at the same time meet the requirements for structural durabi-
lity and corrosion resistance. An innovative alloy (Scalmalloy®)
was investigated as a possible solution. AlMgScZr is a material
that combines the good corrosion resistance and welding
properties of AlMg alloys with the increased strength offered
by precipitation hardening (Al3Sc(+Zr) phase). The higher
strength of this material is the result of rapid cooling from the
molten state. Previous studies demonstrate the viability of melt
spinning in this context (cooling rate 104 to 106 K/s). It has
been typically applied to extruded parts.
Using SLM with the same range of cooling rates will
enable the manufacture of complex 3-D parts with increased
strength, a task that was previously not possible.
Result and applications
The primary objective when qualifying a material for SLM is to
obtain a component density approaching 100 percent without
any cracks, fusion defects or pores. This involves evaluating
the process parameters, especially scanning velocity and laser
output power, required to produce components with a density
addITIve ManufacTurIng of hIgh-sTrengTh aLuMInuM coMPonenTs
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