Uses of Aluminum for medieval weapons and armor

Factual Questions
1

OK, first of all I’m not a metallurgist or expert on medieval weapons, so feel free to correct any misunderstandings I might reveal. My understanding is that aluminum is a very common element, however it is almost always found in the form of aluminum oxide which is nearly impossible to smelt into metallic aluminum by conventional heat/chemical methods used for other ores. Instead it is smelted electrically.

Now, this means that until electric generators were in widespread use, there was no source of metallic aluminum. But suppose medieval or ancient smiths had access to large amounts of relatively cheap metallic aluminum? Time travellers, aliens, wizards, elves, let’s not worry too much about the source, only that these smiths don’t really know how to smelt aluminum ore themselves, they just get aluminum ingots and can do whatever they wish with them, so we don’t have to postulate medieval electric power. So given that, what sorts of things would aluminum be most useful for, compared to steel? If you wish, you can expand back to the bronze age, or forward to the early age of gunpowder, but I’m primarily interested in aluminum as a replacement or supplement for steel, especially in warfare.

Aluminum is lighter than steel or bronze, but not as strong. I believe steel is harder, but steel is also more brittle. Therefore, aluminum wouldn’t hold an edge as well as steel, but it wouldn’t break as easily either. But could medieval techniques work with aluminum? You could pound aluminum into shape, but don’t modern metalworkers need special torches to weld aluminum? If you couldn’t weld the stuff, would it be worthwhile?

Given that, would aluminum make good armor? I believe aluminum is fairly ductile, could you make wire and then chain-mail armor from it? Would a full suit of aluminum high-medieval plate be any good? Would it be useful for simpler metal plates sewn over leather armor? How about for shields or helmets? Or would you have to increase the thickness of the armor to offset aluminum’s weakness that you would get no net benefit?

How about for weapons? Aluminum arrowheads sound like a good idea. I don’t know anyone who makes swords or knives out of aluminum today. Why is that? Is there any fundamental reason why aluminum edged weapons don’t work well? Is aluminum just too soft? I suppose you could make things like very strong spear shafts out of aluminum tubes, but would making those tubes be too labor intensive for a medieval smith? If you HAD to make a weapon out of aluminum, what would be your best bet?

Also, how about simple gunpowder weapons? What would be the drawbacks of aluminum cannons or flintlocks? I know most early cannons where bronze or brass rather than steel, why was that, and would cheap aluminum have been an acceptable substitute for expensive bronze?

I guess I’m generally imaging two scenarios: a smith with a pile of iron ingots and a pile of aluminum ingots and what they would make in that case, and a smith with only a pile of aluminum ingots and what they would make then. If you had both aluminum and steel Would there ever be an occasion where it would make sense to reach for the aluminum rather than the steel?

2

Aluminum chainmail certainly does exist. It’s quite malleable and very light – more so than iron or steel, so it’s more suited to hobby use. I’ve made a few square inches of chainmail out of both materials, and it’s certainly far easier with aluminum wire. The result is also much lighter. Iron chainmail is very heavy, so aluminum is better for reenactment purposes. I have no idea, though, how it would hold up in real battle. Some drawbacks include the brighter, whiter color of aluminum and the very fact that it’s lighter. Holding an aluminum hauberk is much less satisfying than an iron one.

I don’t think aluminum plate would be very good, because aluminum is more flexible than iron and wouldn’t deflect blows very well. It would have been excellent in the latter days of plate armor when suits of plate were mostly status symbols. It would have been much like owning a suit of gold plate.

As far as weapons, I think aluminum would be too soft. It probably couldn’t hold an edge, and a lot of aluminum weapons would bend under the stress of battle. Perhaps some things where weight is a factor might be practical – a spear shaft, maybe. I certainly don’t think aluminum would have been world-changing in that an army outfitted with aluminum weapons would have conquered the world.

3

Aluminum doesn’t hold an edge as well as steel. It’s a less dense, softer metal. A sword blade made from aluminum will lose its edge very fast. You don’t want to make weapon tips out of it.

Casting aluminum isn’t hard, so a medieval smith with a pile of aluminum ingots and not much else beyond what they’d already have could make cast aluminum parts easily. But cast aluminum is much more brittile than steel. I don’t know if I’d trust armor made from it.

4

How it was used would depend largely on how rare it was. Since it does not tarnish easily, it could be used for jewelry and ornamental plates, bowls, and cups, provided its rarity was kept sufficiently high.

If it became common, it would still be good for dishes, but for people of a different social standing. (Hey, it still beats wood.) Also good for containers. Beer kegs come to mind, but a lot of bulk goods were transported in barrels. Only if the material was cheap, though.

Bells, aglets, and other costume bits could be made of aluminum.

5

Well I’m not a metallurgist, but I am a schollar of Medieval Martial Arts, so I’ll give you my cents worth.

First off aluminum IS used for swords now a days. Specifically for practice swords.

And let me tell you, as long as the craftsmen is capable, aluminum makes great PRACTICE swords. They handle almost like real weapons and you can be confident that even in a heated full-speed match they are not going to injure your opponent, even if the score a telling a blow (given some light padding).

But as yourself pointed out, there are limitations to this metal which would make it inferior to steel when it comes to swords and armor.

Most important on the list: It’s not hard enough. This means a sword will not hold a sharp edge. It means it’s resistance to shock is reduced as well (with steel you can balance hardness with toughness much better so as to produce both a hard sword that holds an edge and a flexible sword that will bend 90 degrees and return to it’s true shape.).

The same holds true for armor. If it’s not strong enough to stop an incoming blow, it is of little use.

Perhaps someone more in the know about metallurgy can chime in and help us fill in the rest of the blanks :wink:

6

If I recall correctly, a mixture of aluminum and iron filings makes a nice explosive. I was warned to clean grinders real well between uses for this reason…

7

We can set aluminum now, but I don’t think the technology to get the metal out of the ore in any appreciable amounts existed then.

In order to serve as useful armor I believe it would have to be one of the aluminum alloys and not the pure metal.

8

[Warning: utterly frivolous post.]

OTOH, to imagine how the anachronistic advent of aluminum could have altered military history, consider this revisionist version of the great battle scene from Braveheart:
SCENE 42.

[Setting: The two great armies, those of Braveheart’s Scots in blue body-paint and the English-allied Irish mercenaries, view each other tensely from across a distance of about 50 yards across the great plain.]

After a suitable pause, Braveheart strides forward five yards, with his left hand conspicuously behind his back. He stops and reveals what he has been concealing: a shiny, aluminum beer can (albeit with the old-fashioned tab-top feature).

[CLOSEUP on beer can]

He holds this mysterious object on his outstretched palm and displays it to the Irish hordes with a majestic, broad wave.

[PAN SHOT: Both sides are raptly fascinated with this bit of battleground theatrics, although the Scots are grinning with anticipation, well-knowing what comes next.]

A grin steals over Braveheart’s face, as he grips the can with both hands. With a single confident move, he rips off the top, and the sound of the carbonated hiss reverberates across the plain. With a second move, he upturns the can and chugs the entire contents in one great uninterrupted chug. And with a third movement, Braveheart cradles the can at its base, and, fixing his fanatic, unblinking glare on the Irish pikemen, smashes the can against his forehead…

[CLOSEUP on the beer can crumpling against forehead]

…and belts out a ferocious, barely articulate roar of unbridled testosterone and macho-ness: “TASTES G-G-GR-REAT!!!”

[CUT to Irish lines]:

[long beat] [unison] “LESS FILLING!!!”

[CUT to Scot lines]:

[unison] “TASTES GREAT!!!”

[PAN SHOT]

[unison]“LESS FILLING!!!”

[unison]“TASTES GREAT!!!”

[All together in disorganized, jumbled unison, for a few seconds, their cries intermingling and breaking up in laughter. The lines break, tentatively at first, and then in a rush, as Scots and Irish rush forward to embrace as kin.]

[CUT to the English commanders]: The English break and run.

9

I note that you covered the difficulty of getting it. Sorry I brought it up.

The fuselage armor of WW II aircraft was aluminum alloy, wherever there was such armor.

10

Well, I’m certainly not wedded to pure aluminum. Could our medieval smiths create their own alloys? What other elements would they need to make stronger alloys? Or would they need to be given alloy ingots?

11

Lots of fighters in the SCA used aluminum for armor. In smaller pieces (legs & arms) it was very popular. For helmets, steel was required.

The alloy is important. If you get the wrong alloy, it dents too easily or is too brittle. The right alloy is springy and durable.

Consult your local SCA armorer for the right alloy - it’s been too long for me and I don’t remember. I do remember that is was considered an “aircraft grade”.

Strange, too, how may street signs are made of nice aluminum plates. Strange, too, how much SCA armor was reflective on one side.

12

I wouldn’t recommend the SCA for any sort of weapons or armor advice.

They come from a stage fighting background and do not practice medieval martial arts. They could probably point out a ‘nice looking’ piece, but not a very functional one.

13

Oh - and refining aluminum is purely a modern process. I remember a description of a debate about the finial for the Washington monument. The debate was over the three valuable metal choices, gold, silver, & aluminum.

14

I disagree. The SCA is one of the few groups making functional armor. It’s not always historically accurate but it is decently close and definitely protective. (closed cell foam underpadding is not period but it is safer).

If all you’ve experience is public demonstrations of SCA combat (note the implied qualifier) then you’ve only seen deliberately “stagified” combat - to entertain the modern folk.

15

I’m 100% certain all SCA does IS staged combat. With the exception of a handful of members, the SCA Does not teach medieval martial arts or historical fencing.

I have seen private and public displays from them here in new jersey myself. I know historical fencing when I see it.

16

Aluminium would be completely useless for edge weapons such as swords and axes because it is too soft; try a blocking move and a steel sword would cut right through it - even hacking into an unarmed, unarmoured person with it would damage the edge (or deform the shape, if you hit bone).

It might work for arrowheads, in fact there’s a certain advantage to making them so that they are usually destroyed on first use - makes them harder to pick up and re-use against you.

I think an aluminium cannon, if it didn’t simply split open, would erode in the bore quite quickly and this would result in structural flaws, leakage of pressure and inaccuracy.

Aluminium and its alloys would have found uses in construction of lightweight ladders and siege towers etc.

Except (and I think the OP realises) it simply wasn’t available.

17

About the only way any reasonable thickness of Al could be useful against iron-headed weapons is to combine it with other materials.

For example, you could make a decent but light armor from bilayer plates of steel/iron + Al. The outer layer would provide some impact resistance against iron weapons, and the lighter (thicker) aluminum, could provide rigidity. Aluminum is 1/3 the density of iron.

I suppose you could make a light (compared to iron) but very hard single-battle shield by pouring 1/2" or more of low melting point glass (also 1/3 the density of iron) into a hollow Al form made from plate aluminum. (Glass that melted well below 660C was used in the medieval era.) You might use a two-part inner/outer Al form rather than a deep hollow mold for fabrication reasons.

Such a shield could, after testing and refinement, join the hardness and lightness of glass with the shatter-resistant ductility of Al. Iron weapons could dent or cut the aluminum casing, and crack the glass within, but the Al would still hold it together. It would certainly kill the edge of any iron/steel sword. Between battles, you remove the cracked glass for remelting, and fix or re-manufacture the shell.

Perhaps a decent composite might be made from aluminum and formed pottery? How about glass aluminum and pottery? (I know, I’m giving your craftsmen headaches) I’m certain I’m overlooking some killer leather-Al composite application. How about multilayered wood/Al shields with crossed grain layers? I can see that being more shock-absorbing and less deformable than AL alone.

I agree that Al would have benefits over wood for war machines - but many are as much due to its workability and our modern engineering knowledge, as its density or other bulk properties. Their metalsmiths were good, but they still wouldn’t have our centuries of added experience and concepts - like adding strength to sheet constructions with formed grooves, honeycombing or corrugation.

18

Gotta disagree with you on this one. My sister was active in the SCA for many years and I used to go to fighter practice a lot. There is absolutely nothing staged about it. I’m certainly not an expert on medieval weaponry, armor and martial arts however a lot of the SCA’ers are really into that stuff. Medieval historians, blacksmiths, martial artists were very common. While a number of the folks I knew had done a lot of stage fighting, that was not what they did in SCA battles - they are really going at it with those rattan weapons. I won’t vouch for the historical authenticity of any particular move, but those folks are really trying to hit each other hard enough to register a solid “wound”, the armor really has to stop hard blows, and they are really dodging, blocking and parrying so as not to get smacked.

19

Whoops, sorry - r.e. the OP:

There’s a reason you don’t see much aluminum used for blades - too soft and won’t hold an edge. As Kinthalis said about aluminum practice swords:

" They handle almost like real weapons and you can be confident that even in a heated full-speed match they are not going to injure your opponent, even if the score a telling a blow (given some light padding)."

I know, I know, a lot of this is because they’re blunt but still, that’s not a recommendation that will send me charging into battle with an aluminum broadsword :slight_smile:

As others have said there are probably aluminum alloys that are much stronger and might make good armor, but I don’t know if the weight advantage would be enough to turn a battle. “Real” mail and plate are surprisingly maneuverable.

Aluminum tubing makes very nice light arrow shafts though. Dunno how well a blacksmith of the time could produce them.

20

Hrm.

After reading a few posts, I offer only a few pointers:

As a bona fide, certified Armchair General, I would totally use aluminum as arrowpoints. Think of it this way, an arrow is a “fire and forget” weapon. While unguided, chances are you won’t get it back. Sharpen your aluminum point as best you can to a point, and let the kinetic energy of the arrow itself punch through the armor of the Communists once, which will be the arrow’s wartime service life. Besides, with a lighter tip (aluminum is lighter than iron or steel), you could get a better range out of your shot.

Besides that, I would never train my troops with aluminum swords and arms. I want them guys to learn the steel and iron. I want them to be able to swing a 20# Claymore on the battlefield without hesitation. I want that 7# kitana to slice through the Communist heads.

Tripler
But hey, use your materials as best as they’re well suited.