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JOSH: In order to get
Astronauts beyond the

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International Space Station,
NASA needs the most advanced

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materials, and innovative ways
to tie it all together.

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Take a closer look at the
leading edge of the

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technology that will launch us
towards the lunar surface...

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It’s lessons in heavy metal...
and it’s next on Real World.

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? [music] ?

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To create a very special
spacecraft... one that could

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one day take astronauts back to
the moon...

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NASA is using some very special
parts.

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The Ares I rocket is made up of
advanced materials and amazing
engineering.

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Take for instance the
spacecraft’s skin.

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Ares 1’s shell will be made
from Aluminum-lithium 2195,

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which is very strong and very
light.

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But when you weld pieces of
this material together...

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using traditional fusion
methods that melt the metal...

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you get big problems in the
form of tiny holes.

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These small pores weaken the
metal and make it useless

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in an application like Ares 1.

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So NASA needed to find a better
way to do it.

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ROBERT CARTER: Here at the
Marshal Space Flight Center, we
do friction-stir welding.

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JOSH: Robert Carter is shop
floor lead in the Weld

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Process Development Facility at
the Marshal Space Flight

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Center in Huntsville, Alabama.

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ROBERT: Friction-stir welding
is a solid state welding
process.

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Solid state means that there is
no melting involved in this
process.

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JOSH: In conventional fusion
welding, pieces of metal are

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melted at their common area and
joined together.

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But this is different. In
friction-stir welding the

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heat and force cause the two
pieces to become one.

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Yeah... I weld.

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ROBERT: The way it works is we
have what we call a pin-tool,

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this is a pin-tool, and this
tool is rotated at several
hundred rpms.

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It’s plunged into the surface
of a work piece with

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tens of thousands of pounds of
force.

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It’s then traversed along this
weld joint while it’s rotating,

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til it gets to the end of a
weld and then we retract,

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and that’s the end of the weld.

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JOSH: So the friction causes
the heat. The faster the pin

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tool rotates and the faster the
traverse, the more friction,

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and thus, more heat. The heat
softens the metal,

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but it doesn’t melt it. This
state where the metal is soft,

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but not liquefied, is known as
plasticity.

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This happens at about 800
degrees Fahrenheit for most
metals.

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To find the Celsius equivalent,
Subtract 32

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from the Fahrenheit
temperature, 800 and

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multiply by five-ninths. That’s
nearly 427 degrees Celsius.

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The force applied to the soften
metal by the rotating

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pin-tool, turns the two pieces
of metal into one seamless
solid sheet.

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ROBERT: If you look at the very
beginning of this plate

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here you can see that this was
originally two pieces of

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metal that have been welded
together using friction-stir
welding.

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And then just to look at the
back, when we perform

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friction-stir welds, we’re
pushing up against a solid
backing anvil.

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And so this is what the root
side of the weld joint looks
like.

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It’s completely smooth.

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JOSH: For welding two very
large pieces together,

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Robert uses a slightly
different process.

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ROBERT: There is another
version of friction-stir

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welding that we developed here
at Marshal called self-

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reacting friction-stir welding,
which is done with a

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tool that looks like this. And
what we do in self

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reacting is rather than having
this type of pintail,

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which would push against a
solid backing anvil,

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we actually install the tool in
the plate, like so,

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and we pinch the part between
two shoulders, while this

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assembly is rotating and
traveling.

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So in this process what we do
is we eliminated the need for a
backing anvil.

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The benefit there is it makes
our tooling somewhat simpler

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and easier to fabricate when
we’re building large scale.

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JOSH: Without stir friction
welding, Ares I might never

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be able to get off the ground.

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ROBERT: We get improved
mechanic properties over

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conventional fusion welding. We
also tend to produce fewer

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defects and those two things
together mean we can build a

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vehicle that’s lighter because
the improved

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strengths allows us to reduce
our weld and thicknesses.

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So we have better tensile
strength, and also we have

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improved fracture properties.

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Basically that means that there
is less of a propensity for
cracks to grow.

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In general, friction-stir welds
have strengths that are

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roughly 20 percent better. That
means a 20 percent

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improvement in mechanical
properties relative to fusion
welds.

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JOSH: They do all the work in
this huge building at Marshal.

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ROBERT: This facility is called
the Weld Process

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Development Facility.
Everything you see in here

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right now today is being
designed, developed,

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installed specifically to build
Ares I upper stage full

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scale developmental hardware.

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So we’re going to be building
manufacturing demonstration
article.

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We’re also going to be building
potentially at least,

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some of the structural
development test articles

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that will be used for the Ares
1 upper stage.

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We’re developing all the
manufacturing techniques so

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that we can find the problems
and work out the bugs,

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even develop our tooling
designs, develop our fixture

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designs, develop the software
for the weld tools.

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We do all that up here at
Marshal, offline, so that we

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don’t end up having to solve
these problems on the shop
floor.

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JOSH: All this hard work and
amazing engineering has this

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next generation spacecraft
pointed in the right

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direction as NASA looks beyond
the space station,

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to take astronauts to new
worlds.

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Follow the journey at
www.nasa.gov.

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? [music] ?

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.