Aerospace & Defense Technology - December 2021 - 14

Finding the
Perfect Aluminum for
Additive Manufacturing
W
hen weight reduction is
the
primary
goal,
3Dprinted
aluminum alloys
are a frequent choice for
aerospace and high-performance motorsports
applications. Aluminum is
much lighter than nickel alloys and has
been particularly popular for laser powder-bed
fusion (LPBF) because it's good
for prototyping and easy to postprocess.
There
are indeed lightweight metal alloys
with higher specific strengths (a
better ratio of strength to density) than
aluminum, such as the titanium grades.
In the case of thermal management,
there are certainly materials with better
heat-transfer coefficients, such as copper
alloys. For the lowest density or a higher
galvanic potential,
magnesium
alloys are
also a
great choice. But aluminum alloys have
persisted because, when it comes to the
trade-off between cost, performance,
and manufacturability, they remain
among of the best materials to optimize
all three.
These same trade-offs drove much of
the early development in aluminum
when it came to metal 3D printing, especially
LPBF. Aluminum alloys are generally
grouped as either casting alloys or
wrought alloys, and much of the original
success in printed aluminum was
with casting alloys. Wrought alloys can
be desirable for demanding applications,
particularly in aerospace where alloys
like 2024, 6061, or 7075 see a lot of use,
but these higher strength alloys suffer
from poor weldability. Even 6061,
which is considered to be a weldable
aerospace-grade alloy, isn't well-suited
for laser powder bed fusion. Since LPBF
is at its most basic level a welding
process, how can this be the case? It
turns out that " weldability " is not the
primary criterion here, but rather " autogenous
weldability " .
Autogenous weldability means that
an alloy is weldable without a filler
material. This isn't as much of a problem
in a normal welding application,
but the powder bed in an LPBF printer
is a single material, meaning that
there isn't a great way to get a " filler "
into the process. Because of this, alloys
that aren't autogenously weldable can
present a problem, which in many of
these cases presents itself as a tendency
to crack while printing.
So, casting alloys
took
t h e
14
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Aerospace & Defense Technology - December 2021

Table of Contents for the Digital Edition of Aerospace & Defense Technology - December 2021

Aerospace & Defense Technology - December 2021 - Intro
Aerospace & Defense Technology - December 2021 - Sponsor
Aerospace & Defense Technology - December 2021 - Cov1
Aerospace & Defense Technology - December 2021 - Cov2
Aerospace & Defense Technology - December 2021 - 1
Aerospace & Defense Technology - December 2021 - 2
Aerospace & Defense Technology - December 2021 - 3
Aerospace & Defense Technology - December 2021 - 4
Aerospace & Defense Technology - December 2021 - 5
Aerospace & Defense Technology - December 2021 - 6
Aerospace & Defense Technology - December 2021 - 7
Aerospace & Defense Technology - December 2021 - 8
Aerospace & Defense Technology - December 2021 - 9
Aerospace & Defense Technology - December 2021 - 10
Aerospace & Defense Technology - December 2021 - 11
Aerospace & Defense Technology - December 2021 - 12
Aerospace & Defense Technology - December 2021 - 13
Aerospace & Defense Technology - December 2021 - 14
Aerospace & Defense Technology - December 2021 - 15
Aerospace & Defense Technology - December 2021 - 16
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Aerospace & Defense Technology - December 2021 - 18
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Aerospace & Defense Technology - December 2021 - 20
Aerospace & Defense Technology - December 2021 - 21
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Aerospace & Defense Technology - December 2021 - 24
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Aerospace & Defense Technology - December 2021 - 26
Aerospace & Defense Technology - December 2021 - 27
Aerospace & Defense Technology - December 2021 - 28
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Aerospace & Defense Technology - December 2021 - 30
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Aerospace & Defense Technology - December 2021 - 33
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Aerospace & Defense Technology - December 2021 - 37
Aerospace & Defense Technology - December 2021 - 38
Aerospace & Defense Technology - December 2021 - 39
Aerospace & Defense Technology - December 2021 - 40
Aerospace & Defense Technology - December 2021 - Cov3
Aerospace & Defense Technology - December 2021 - Cov4
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