
New technique can weld “un-weldable” metals - Oatseller
https://news.osu.edu/news/2015/10/29/vfaweld/
======
nkurz
I learned recently of another surprising welding technique. It turns out that
if you rub together the right kinds of wood at the right speed, you can
actually weld wood to wood!

Friction Welding of Wood (text):
[http://ibois.epfl.ch/page-20697-en.html](http://ibois.epfl.ch/page-20697-en.html)

Linear friction welding of wood (video):
[https://www.youtube.com/watch?v=X0k04hjdYuQ](https://www.youtube.com/watch?v=X0k04hjdYuQ)

~~~
pjbrunet
That's what wood glue is for, it's strong as wood if your joint is tight.
Personally, I love the look of box joints. Buy a chisel and try one, it's
mesmerizing.

~~~
ar0b
If you haven't already, check out this youtube channel:
[https://www.youtube.com/user/Matthiaswandel](https://www.youtube.com/user/Matthiaswandel)

~~~
Dowwie
[https://youtu.be/W1pvUlQgYtk](https://youtu.be/W1pvUlQgYtk)

~~~
provemewrong
Ah yes, reminds me of the night when I was binge watching Japanese woodworking
videos. That dovetail joint, man.

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vlehto
>new welding technique that consumes 80 percent less energy than a common
welding technique, yet creates bonds that are 50 percent stronger.

I don't care at all about the energy required. It's peanuts anyhow compared to
making steel. You can use less steel with better welds, because you don't need
to compensate so much. "50% stronger than previous welding" doesn't really
mean anything. "80% strength of the base metal" would be really cool.

>Within microseconds (millionths of a second), the foil vaporizes, and a burst
of hot gas pushes two pieces of metal together at speeds approaching thousands
of miles per hour.

Explosion welding isn't exactly new. They seem to have developed more
accurate(?) or less energy incentive(?) way to explosion weld. The article
doesn't say. And how loud is this?

>The technique is powerful enough to shape metal parts at the same time it
welds them together

Probably this is disadvantage. Likely they need to make counter recess for the
welds, and afterwards smooth things out with something.

This technology seems very cool. But the article is really bad. Anyhow, it's
so interesting that I'd actually welcome OP to do this again.

Could I get the same results with very powerful laser peening equipment?

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542458
So it's electronically (rather than chemically) powered explosive welding?
Neat. Unfortunately, the last picture on the article seems to suggest it
causes a fair amount of material distortion, and doesn't weld at the centre of
the joint, only the edges. Still, very cool - I'm not sure automotive is the
right application area, but I'm sure it will be applications. Corrosion-
resistant cladding for petrochemical applications, or maybe even in-orbit
assembly comes to mind.

~~~
csours
Ohio is smack in the middle of the rustbelt - Automotive is on their mind.

Mixed material cars are here [1]- weight kills fuel economy and perceived
power (power to weight ratio).

My immediate thoughts turn to safety and industrial hygiene related to
exploding metal. I wonder if this releases more or less metal vapor than other
methods. How loud is this?

1\. [http://articles.sae.org/13986/](http://articles.sae.org/13986/) 2\.
Bonus: video on the process:
[https://www.youtube.com/watch?v=CB2QnbSfmw0](https://www.youtube.com/watch?v=CB2QnbSfmw0)

Disclosure - I work for GM, but not in this area; any opinions are solely my
own.

~~~
tim333
Cool. They actually vaporize the foil at 5m18s for those in a hurry. It looks
like you could use it in similar places to where spot welding it used in cars
but to bond say steel-aluminium rather than steel-steel.

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dexwiz
The fundamentals of this technique seem to be similar to blast welding, but
more controlled. Blast welding is used in all sorts of high strength
applications, like vault doors. But its expensive, requires big pieces, and
ends up warping the material.

Material processing, specifically metals, often involves heating the metal to
high heats, and then controlled cooling. The max temperate and rate of cooling
and completely change a metal's properties. Pearlite in steel is the classic
example. Welds basically remelt the material and negate any processing gains.

If this can be cheaply replicated, and can be adapted to different
configurations, it will be revolutionary. But reading the article, it requires
aluminum for vaporization, and looks to only bind two flat surfaces, where
one's backside is easily accessible.

~~~
RyJones
it's interesting how very close the margin in the micrographs they show looks
to explosive welding.

The ones on page 2053 (warning, PDF, but it isn't 2000+ pages)
[http://www.jim.or.jp/journal/e/pdf3/47/08/2049.pdf](http://www.jim.or.jp/journal/e/pdf3/47/08/2049.pdf)
are the ones I'm on about.

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OopsCriticality
How would you minimize galvanic corrosion with this technique, if it were used
for cars?

edit: to be specific, this technique would seem to require that you prevent
galvanic corrosion through surface coatings, but that doesn't seem to me to be
a lasting solution for consumer automotive applications. It would seem like
adhesives would be a superior choice since they can insulate the different
metals from one another, reducing the need for the surface coating to maintain
integrity.

~~~
phasetransition
Adhesives (e.g. ITW Plexus) are used in automotive, but your typical car has
all kinds of galvanically wrong things going on inside. There are lots of
techniques that have been developed to deal with the couples. Automotive
industry have also developed more robust corrosion testing standards (e.g. SAE
J2334).

Appeal to Authority: I don't work in the automotive industry, but I do use an
automotive coating system for day job products that need high levels of
corrosion protection.

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Animats
Nice. That's very similar to the exploding foil initiator used to detonate
nuclear weapons. The video doesn't give any of the electrical specifications,
though.

~~~
jandrese
So I guess we shouldn't try to use this technique to weld refined uranium to
steel?

~~~
aidenn0
The precisely timed implosion lens is typically used for plutonium bombs, not
uranium ones. A fairly bog-standard explosive can be used for uranium bombs
(but plutonium is much more easily manufactured than sufficiently enriched
uranium)

~~~
InclinedPlane
Plutonium is more easily manufactured than highly enriched Uranium _if you 're
just starting out_. If you have the industry set up, then it's easy peasy. In
the developed world there's Uranium enrichment facilities everywhere and in
nuclear powers they have HEU up to their ears.

Indeed, a lot of modern bombs (which are entirely implosion based) use HEU
extensively in their design. Generally, they tend to still use Plutonium in
the primary mostly because it saves on size and weight, which is hugely
advantageous when it comes to long range ballistic missile delivery. But most
compact sub-megaton thermonuclear weapons derive the majority of their yield
from HEU in the secondary.

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cmsmith
I found this webpage with a video of the weld in action:

[https://iml.osu.edu/vfa-welding](https://iml.osu.edu/vfa-welding)

Very cool stuff - I'd be interested to see some non-theoretical strength test
data and more application-ready packaging.

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nwmcsween
This seems like just a more refined EXW (Explosion welding) technique, the
'ridge' weld shape is a dead giveaway. EXW has a major drawback though - it's
useless for field word or anything not somewhat flat.

~~~
saulrh
Yep, one of the images at the bottom shows that they're welding flat sheets of
metal together by using a capacitor bank to vaporize a foil sheet to provide a
plasma blast that smashes the target metals together. So, yes, more controlled
explosive welding.

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ars
"Also, high-strength steel and aluminum join together with weld regions that
are stronger than the base metals."

Does that mean they can create a new "alloy" made entirely of this join?

~~~
elif
I hope you're right. That's what excited me when reading this too.

If the joints are stronger than both materials, we can make layered metals
that are crazy strong, and selectively apply more layers only when needed
(like carbon fiber).

~~~
roel_v
How would that work? Say you have a 'rod', something like this:

    
    
        AxBxAxBxAxB
                  |
                  v
    

Where A and B are the two different metal, and the x's are the joints that are
stronger than either A or B.

Now we apply force in the direction of my crude vector. Won't it just break at
an A or a B section?

(I know nothing about all of this, just wondering what I'm missing)

~~~
ars
The assumption is that the joint is not a single line, but rather extends into
the metal of both A and B to either side, so the whole rod is X.

Option 2:

    
    
        AAAAAAAAAAAAAAAAA
        xxxxxxxxxxxxxxxxx
        BBBBBBBBBBBBBBBBB
                        |
                        v

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eghad
Keep in mind that this is still very much a press release, so of course it
manages to sensationalize.

These metal combinations are only "un-weldable" via fusion welding, other
solid state welding techniques (like explosive welding, as others have noted)
can accomplish this as well. Furthermore, looking at the papers on the
technique [1][2] the increased weld strength has only been observed in a few
combinations of alloys and isn't significantly greater than other collision
based methods. While the energy and scale reductions this accomplishes are
worthy of praise, geometry restrictions, intermetallic generation and fatigue
behavior within these welds are still issues.

[1][http://www.sciencedirect.com/science/article/pii/S0924013613...](http://www.sciencedirect.com/science/article/pii/S092401361300232X)
[2][http://link.springer.com/article/10.1007%2Fs11661-014-2404-0](http://link.springer.com/article/10.1007%2Fs11661-014-2404-0)

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pjbrunet
I assume this means we'll see more beautiful automobiles in a few years.

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TTPrograms
Reminds me of making clad via explosion welding:
[https://www.youtube.com/watch?v=2u51tJdRDK0](https://www.youtube.com/watch?v=2u51tJdRDK0)

~~~
hzg
That same weld pattern from the article can be seen here in the explosion
welding video (~7:50):
[https://youtu.be/2u51tJdRDK0?t=7m50s](https://youtu.be/2u51tJdRDK0?t=7m50s)

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sitkack
Wonderful taxpayer funded research that will see limited diffusion into
industry. So in effect, we all pay twice while innovation at the edges is
denied access. Research shouldn't be "in business"

