WELDING
NANOTECHNOLOGY
ENABLES ENGINEERS
TO WELD PREVIOUSLY UN-WELDABLE ALUMINUM ALLOY
SUPER-STRONG BUT LIGHTWEIGHT, AA 7075 NOW COULD BE MORE
WIDELY USED IN AUTOMOBILES AND OTHER MANUFACTURING
THANKS TO UCLA RESEARCH
In the world of engineering, where
there’s a will there is a way.
And that’s exactly what a team of
scientists and engineers has done,
found a way to do the un-doable.
An aluminum alloy developed in the
1940s has long held promise for use
in automobile manufacturing, except
for one key obstacle. Although it’s
nearly as strong as steel and just
one-third the weight, it is almost
impossible to weld together using
the technique commonly used to
assemble body panels or engine
parts.
That’s because when the alloy is
Communications.
Using the new approach, the
researchers produced welded joints
with a tensile strength up to 392
megapascals. (By comparison, an
aluminum alloy known as AA 6061
that is widely used in aircraft and
automobile parts, has a tensile
strength of 186 megapascals in
welded joints.) And according to the
study, post-welding heat treatments,
could further increase the strength
of AA 7075 joints, up to 551
megapascals, which is comparable
to steel.
Because it’s strong but light, AA
7075 can help increase a vehicle’s
fuel and battery efficiency, so it’s
already often used to form airplane
fuselages and wings, where the
material is generally joined by
bolts or rivets rather than welded.
The alloy also has been used for
products that don’t require joining,
such as smartphone frames and
rock-climbing carabiners.
But the alloy’s resistance to welding,
specifically, to the type of welding
used in automobile manufacturing,
has prevented it from being widely
adopted.
“The new technique is just a simple
twist, but it could allow widespread
use of this high-strength aluminum
heated during welding, its molecular
structure creates an uneven flow
of its constituent elements —
aluminum, zinc, magnesium and
copper — which results in cracks
along the weld.
Now, engineers at the UCLA
Samueli School of Engineering have
developed a way to weld the alloy,
known as AA 7075. The solution:
infusing titanium carbide nanoparticles
— particles so small that they’re
measured in units equal to one
billionth of a meter — into AA 7075
welding wires, which are used as
the filler material between the pieces
being joined. A paper describing the
advance was published in Nature
26 March 2019