WEBVTT - How Does Captain America's Shield Work?

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<v Speaker 1>com slash brain Stuff. Welcome to brain Stuff from how

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<v Speaker 1>Stuff Works. Hey, brain Stuff, I'm Christian Sager. The official

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<v Speaker 1>Marvel Comics database says that Captain America's shield is a

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<v Speaker 1>metal disc that's approximately two point five feet in diameter

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<v Speaker 1>and weighs twelve pounds, But Rheta. Laine at Wired Magazine

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<v Speaker 1>did some math and figured out that it would be

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<v Speaker 1>more likely to weigh forty three point nine pounds, despite

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<v Speaker 1>the shield being made of a unique alloy combining vibranium,

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<v Speaker 1>which is a fictional metal steal, and an unknown third component.

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<v Speaker 1>Elaine also figured out that the density of the shield

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<v Speaker 1>would be somewhere between eight thousand, seven hundred and sixty

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<v Speaker 1>seven and four thousand, three eighty three kilgrams per meter cubed.

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<v Speaker 1>That is, somewhere between the density of iron and titanium. Now.

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<v Speaker 1>In the Captain America comics, the story goes that Dr

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<v Speaker 1>Myron McLean was attempting to replicate hercules golden mace by

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<v Speaker 1>fusing vibranium with an experimental iron alloy. Some say it

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<v Speaker 1>was a steel alloy, but even McClain didn't know what

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<v Speaker 1>it was because he fell asleep when an unknown catalyst

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<v Speaker 1>was introduced to the process. He was never able to

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<v Speaker 1>duplicate the process, so the government painted the disk and

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<v Speaker 1>gave it to Captain America. But how would you forge

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<v Speaker 1>such a thing, especially since metallurgy is so complicated. Just

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<v Speaker 1>the forging temperature alone depends on the materials carbon content,

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<v Speaker 1>it's alloy composition, maximum plasticity, and the amount of reduction required.

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<v Speaker 1>Was it heated by induction or by continue was fuel

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<v Speaker 1>fired furnaces With a material this unique, you would have

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<v Speaker 1>to carefully control the heating process. Now, forgibility is how

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<v Speaker 1>easy or difficult a material resists deformation, And since Captain

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<v Speaker 1>America's shield is indestructible, it would have to be a

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<v Speaker 1>very narrow forging temperature range, meaning it could only be

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<v Speaker 1>forged for a short time after heating. With metallurgical factors

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<v Speaker 1>like crystal structure, chemical composition, and grain size at play.

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<v Speaker 1>The only way McClain could have diminished their influence would

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<v Speaker 1>be by adding alloying elements, possibly compounds that easily dissolve

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<v Speaker 1>within the metal. There are all types of elements that

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<v Speaker 1>could have been introduced, but it's likely that Captain America's

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<v Speaker 1>shield was forged like a super alloy. This is how

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<v Speaker 1>metall aer just referred to iron based, nickel base and

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<v Speaker 1>cobalt based alloys, specifically the ones that offer very high

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<v Speaker 1>strength at high temperatures. These really high string metals and

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<v Speaker 1>iron based grades are the least difficult ones to work with,

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<v Speaker 1>so that would narrow down McClain's experimental alloy to iron.

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<v Speaker 1>Super alloys are really difficult to forge because of their

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<v Speaker 1>narrow temperature range. You can't even use regular sizing presses

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<v Speaker 1>and hammers on them because they'll deform. They even wear

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<v Speaker 1>down the tools designed for forging them pretty easily. They're

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<v Speaker 1>also extremely expensive, like ten times the price of carbon steel.

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<v Speaker 1>Sounds a lot like Captain America's shield, right, But how

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<v Speaker 1>do we explain the shield's ability to absorb kinetic energy

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<v Speaker 1>supposedly from the vibranium in the alloy. Usually materials absorb

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<v Speaker 1>kinetic energy through other mechanisms like plastic or elastic deformation

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<v Speaker 1>or dynamic fluid flow, But cap shield doesn't seem to

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<v Speaker 1>be an elastometric material, and it's not organic like polyurethane

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<v Speaker 1>in the movies. It actually seems to reflect vibration rather

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<v Speaker 1>than absorb it, like when Thor hits it with Mjolner

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<v Speaker 1>in that first Avengers movie and the shock wave flattens

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<v Speaker 1>a whole forest. Perhaps that was because the shield reached

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<v Speaker 1>its absorption limit. Another thing that's tough to explain is

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<v Speaker 1>how aerodynamic the shield is. If it really weighed forty

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<v Speaker 1>three point nine pounds, it would be difficult to throw,

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<v Speaker 1>even for a guy in peak physical condition like Steve Rogers.

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<v Speaker 1>In the comics, Tony Stark actually puts electro magnets under

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<v Speaker 1>the shield to help control it in midflight, but Captain

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<v Speaker 1>America later ditched them because they upset the shields natural balance.

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<v Speaker 1>It seems like the soldier and the shield are made

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<v Speaker 1>for each other. Check out the brain stuff channel on YouTube,

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<v Speaker 1>and for more on this and thousands of other topics,

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