Tuesday, October 22, 2013

Techy Tuesday - Aluminum Armor

I was going to pass on this story, but it ties so nicely to previous posts on universal assemblers making everything for us.  Alcoa has announced that its latest ArmX aluminum armor has been specified for use in US Army vehicles. 
DAVENPORT, Iowa--(BUSINESS WIRE)--Alcoa (NYSE: AA) today announced its latest armor product is now specified for use by the U.S. Army Research Lab (ARL) for use in U.S. military vehicles. Alcoa’s ArmX® 5456-H151 armor plate meets the U.S. military’s highest performance standards for strength, blast absorption, and ballistics resistance for armored combat vehicles where weldability is a material requirement. Alcoa aluminum and armor have been used by the military for decades in vehicles ranging from the Bradley Fighting Vehicle to the Humvee.
Design News reports that the armor has been tested on the Army's (experimental) Fuel Efficient Ground Vehicle Demonstrator (FED) vehicle (pictured).  The Army's lab found it stronger than baseline weldable armor plate with better blast and ballistic performance. 
The product has been around for a while (backgrounder video here); this is a milestone in the performance they get out of it, though. 

Now most of us think of the term aluminum armor as a contradiction in terms, like fiscally responsible Democrat.  Aluminum is soft.  You can cut so-called aircraft aluminum (typically alloy 6061-T6) on a woodcutting bandsaw you'd use for softwoods like pine, and that's the hard stuff.  Pure aluminum - I've seen some in shower curtain rods - is quite a bit softer and literally gums up a saw blade like putty.  This stuff is hard, weldable, and withstands explosions.  As they used to say where I grew up, "how yo did dat?". 

That is certainly a trade secret.  They referred to the alloy as 5456-H151 and that tells us something.  5456 is the series, which Charleston Aluminum (a marine industry supplier) tells us 
This alloy is primarily used in areas where high strength and better welding parameters are required in a marine vessel or other engineering applications. ... [T]his alloy has higher tensile strength than other marine alloys such as 5083 or 5086, and good corrosion resistance in a sea water environment, but not always the formability and corrosion performance of some of the other alloys.
Azom lists its chemical composition.  Now you know virtually everything about it, except that tricky part.  The tricky part is the H151 designation which encodes some information about how its treated and processed to give it the "better blast and ballistic performance".  That's where the trade secrets lie.  And that's the part where your nano assemblers will need to do extremely sophisticated things to all the atoms in the crystal matrices to get those special physical properties without the heat treating and other things they do.  All those things that nobody on earth knows how to do now. 

I think a fair place to end this is the simple question, "Would you trust it?"   I'd like a lot more data.  See, in addition to being kind of soft, aluminum melts at pretty moderate temperatures. Like about 1220F.  That means that if the vehicle should ever catch fire, the aluminum will either melt (which is a really bad thing) or the heat treatment will start to reverse and the aluminum armor will revert to an untreated state (which might be an even worse thing).  For example, with 6061, another alloy designed to be weldable, it starts to lose its special properties as low as about 400 F.  Which tells me the armor will become much easier to shoot through.  Just when anyone behind it in a vehicle that was just attacked may need it the most. 


  1. I think a fair place to end this is the simple question, "Would you trust Them?"

  2. What temperature does it light at? How does that compare to the jet from a HEAT round?

    You know, like the bog standard RPG?

    Remember the M2 Bradley? Remember why it had to become the M2A1? It's got something to do with the 13th element...

  3. Back in the day the Army used to tell the troops that Kevlar would stop an AK-47 round and ballistic fragments moving at 3000FPS. In the early days of the M-2 program "they" said it would stop an M-2 .50Cal. round and was RPG proof. Can you say PROPAGANDA

  4. Sounds like thermite would weaken it sufficiently. They're thinking too hard about bullets and not thinking enough about their opponents getting creative.

  5. Neat stuff. However, if your vehicle is on fire long enough to degrade the heat treatment of the aluminum armor and you're still behind it under fire, you're seriously doing it wrong. Given the stuff that burns inside a typical military vehicle (like ammo, fuel, and big tires that explode) you should be getting the hell away from your vehicle ASAP if it's on fire and you can't control it.

    Ground vehicle armor is about protecting soldiers from shrapnel and small arms fire, not direct hits from anti-armor weapons, be they HEAT, long rod penetrators, explosive formed penetrators, or whatever else. Any armor that is practical on a mobile system is fairly easy to defeat with man portable weapons; that's just how it is and how it will always be.

    If they can improve the strength of the armor without increasing weight, or retain strength and decrease the weight, great. I'd take the extra speed over the extra strength, personally. But until we have some magic/sci-fi energy shields or something, a dug-in infantry heavy weapons squad will have no trouble at all taking out the toughest tanks in the world.

    Just one of the many reasons wars are won with low-tech infantry, not the high-tech toys everyone oohs and aahs over.

    - weambulance

  6. Trade off, weight vs. protection... And of course NONE of those making that decision will actually have to RIDE in them under fire... And no, they will not protect against the newer Iranian burn through jet IEDs.

  7. Excellent bunch of comments. Especially thanks to Old NFO, and weambulance who bring some perspectives I can't.

    War is always a series of moves and counter moves, right? Trades and counter trades.

    Anon 1221, I'm not sure who you mean by Them, Alcoa or the Army? Alcoa? Sure, with the same look I'll give anyone trying to sell me a "new amazing product". Army? Probably. Everyone I've personally known has been an honorable, decent person. In this case, I have no reason to doubt their test results.

  8. Aluminium burns rather well, ask the Falkland sailors that survived HMS Sheffield what they think of aluminium as armour.