The Riddle of Valyrian Steel

In the Song of Ice and Fire series, a Valyrian steel sword is the finest blade any warrior could hope to carry.

Said to be “Stronger than any common steel, lighter, harder, sharper,” with dark, visible ripples running through it showing the thousand foldings needed to craft such a blade. It is nearly indestructible and impervious to ordinary fire.

They say that the blades were spell-forged in dragonflame, but the process for making them was lost in the suspiciously unspecific “Doom of Valyria.”

These Dragonsteel blades do not seem to be magical, though. It appears that the spells were needed to make them, but the material itself may be mundane. If that’s the case, then what might it be?

The fine folks over at the Reactions YouTube channel asked me that, and we made a video about it. Unfortunately, there’s only so much you can fit into a four minute video, so here’s the longer version… the much longer version.

My plan here is to hit the claims made of Valyrian steel one at a time and see if we can come up with a meaningful match…

Valyrian Steel is Folded a Thousand Times

“When Jon turned it sideways, he could see the ripples in the dark steel where the metal had been folded back on itself again and again.” GoT

There is a modern romance with the quality of real, historical blades that were made from layered and folded, or “pattern welded” steel. There are legends about the strength and sharpness of these swords, that a lotus floating down a river would slice itself in two on the edge, that it could cleave a gun barrel in twain. While it is true that many of these were of exceptional quality, important details of the process have been skipped over in the narrative.

Folding metal and forging it out doesn’t do anything good for a blade. It’s actually bad for it. Every fold adds inclusions into the material; bits of oxide, soot, sand and other impurities from the environment would work their way in and mess up the steel.

The actual purpose of historical pattern welding is to mitigate a problem. The problem being that they have good smiths, but bad steel.

Smelting steel requires sustained temperatures well in excess of 1000°C. This is difficult to do and most historical processes had little control over the precise composition of the resulting steel. It would vary in carbon composition, which is the primary alloying element in steel, as well as other desirable alloying elements and less desired impurities. Because of this, historical smelting techniques produced inconsistent grades of steel. Pattern welding was a way of combining some of the soft, low-carbon steel with the hard, high carbon steel.

If those two kinds of steel are layered on top of each other and forge-welded together by applying a lot of heat and force, then the resulting blade would have a combination of the properties. Folding the billet over repeatedly and welding those layers produces a more consistent blend of the materials through the entire piece.

There is a lot of mythology about the near magical quality of pattern-welded blades and claims that the techniques were lost. The techniques have not been lost, but they are now primarily used by artisan craftsmen and mostly for artistic effect. The primary reason for this is that we can now consistently produce steel of a much higher grade that does not benefit from pattern welding.

“Only one metal could be beaten so thin and still have strength enough to fight with, and there was no mistaking those ripples, the mark of steel that has been folded back on itself many thousands of times.” SoS

The notion that the blades are folded over thousands of times is probably playing off of a popular story that some of the finest swords, typically Japanese Katana, have thousands of layers. That can be true, but they were not folded thousands of times. That’s a math error.

Every time a billet is folded over, the number of layers doubles. To get over a thousand layers, one only needs to fold it 10 times. With that number of folds, each layer would be no more than 6 μm thick and would likely not be distinguishable with the naked eye.

Folding it 1000 times, though, would yield 10³⁰¹ layers. That’s a ten followed by three hundred zeroes. For context, there are estimated to be 10⁸⁰ atoms in the observable universe.

My suspicion is that those people in A Song of Ice and Fire making these observations did not extensively study mathematics. Geometric series probably wouldn’t be at the the top of my list of things to learn, either, if half the people I knew were trying to kill me.

“He … had Ice melted down and reforged. There was enough metal for two new blades. You’re holding one.”  SoS

In A Storm of Swords, one Valyrian blade, “Ice,” is melted down and used to make two new swords. If a Valyrian steel sword can be melted down and reforged, then it is definitely not pattern-welded. Melting pattern-welded steel would undo it completely, turn it into a homogeneous alloy somewhere between the two steels used. While this might be desirable in some circumstances, it would not result in a new layered sword.

Why, then, would the people of Westeros keep talking about it as if it were pattern-welded steel, then? I submit that they have no idea what they’re talking about.

This isn’t much of a stretch. The material is stuff of legend. The process to make it is lost to the ages. The people talking about it are not, by and large, smiths. The story about the folding could just be misinformation passed through the generations to explain the swirly patterns. Also, the smith that says he melted down the sword might be lying. The ability to work Valyrian steel is a high value skill and there is definitely precedent for obfuscating trade secrets.

Edit: For those that wodered about Damascus steel, there is a followup post.

Weight

“… the blade itself was Valyrian steel, old and light and deadly sharp.” CoK

There are two possible explanations for Valyrian steel being light. The first is that it is stronger than other steels, and a sword of the same length and width can get away with having less material in it than would a normal sword.

An object’s resistance to bending and twisting is related to its second moment of area. The second moment of area is related to the shape of an object rather than its mass. Because of this, it is possible to remove a lot of material from an object while only slightly impacting how hard it is to bend it. This is why pipes and I-beams remain nearly as strong as their solid counterparts, while being a fraction of the weight.

“The blade itself was a good half foot longer than those Jon was used to, tapered to thrust as well as slash, with three fullers deeply incised in the metal.” GoT

Many swords have fullers in them, often called blood grooves. Their purpose has nothing to do with letting blood. Their actual function is to strip material from the blade while not substantially reducing the strength. The fullers change the mass a lot, while changing the second moment of area very little.

If Valyrian steel is exceptionally strong, then there could be more extensive fullers, reducing the overall weight of the blade.

The second option is that Valyrian steel is not steel at all, but more on that later.

Sharpness

“‘Ice,’ that sword was called. It was as wide across as a man’s hand, and taller even than Robb. The blade was Valyrian steel, spell-forged and dark as smoke. Nothing held an edge like Valyrian steel.” GoT

To cut without dulling, the steel would need to be very hard. Diamond is the hardest known substance, meaning that it can cut anything, and nothing can scratch it. Steel can’t compete with that, however a high-carbon steel, like 1095, with around 1% carbon, can be more than hard enough to cut into other steels without dulling. A lot of modern knives are made out of this, and similar kinds of steel for exactly that reason.

Strength

“‘Valyrian steel,’ he said, ‘spell-forged and razor-sharp, nigh on indestructible.'” FfC

Valyrian steel is supposed to be tremendously strong, but strong can mean a few things when talking about metals. When talking about a sword, it probably refers to a combination of tensile strength and toughness.

We want high tensile strength so that a sword can bend without breaking. Again, a high carbon steel could do that job very well..

Toughness, though, introduces a deeper challenge. Toughness refers to how well a material can take a hit, and the harder something is, the more easily it shatters. So that beautifully hard material we picked earlier might shatter like glass the moment swords cross.

This is the problem Narsil had in Lord of the Rings.

So we need to strike a balance between tensile strength, hardness, and toughness. There are spring steels available that will do this, like 9260. A lower carbon content, around 0.6% along with a couple percent silicon and manganese, creates an alloy that has a very nice balance. It will keep an edge, bend without breaking, and is really difficult to shatter.

Heat Resistance

“The fire melted the silver off the pommel and burnt the crossguard and grip. Well, dry leather and old wood, what could you expect? The blade, now… you’d need a fire a hundred times as hot to harm the blade.” GoT

It is mentioned a few times that Valyrian steel is unbothered by ordinary fire. There isn’t much that can be done to steel to change the temperature it starts to melt at, so this seems ridiculous.

However, while it takes a lot of heat to melt steel, you can spoil a blade at much lower temperatures. Maybe they’re not talking about melting the metal, just annealing it.

Heat treating steel can be a complicated process. To get the crystal structure that gives us the properties we wanted out of spring steel, we would have to heat it to a very specific temperature, cool it down or quench it at a specific rate, then heat it up again to another temperature for a specific amount of time.

Throw that spring steel sword into a burning building and it would ruin the temper, making it too soft to be of any use. In a world without thermometers, it would be hard to get that heat treatment back.

A lot of modern tools heat up and cool down during regular use and it would be inconvenient if they lost their useful properties in that process. There is a class of steel that has been developed for these applications that doesn’t need fancy heat treatment. It just needs to cool off in the open air. Perhaps Valyrian steel is actually an air-hardening tool steel, like A2. This isn’t quite as good a sword material as the spring steel, but it would be pretty robust compared to the common steel of the day.

Also, it would probably take a wizard to smelt that steel in a world like Westeros. It needs a precise combination of chromium, nickel, silicon, molybdenum, manganese, vanadium, and of course, carbon, to do its thing. Most of those weren’t even known elements in medieval times. A process that could smelt them and create a steel alloy with them could well have been considered magic, and may have been such a complicated process that it would have been easily lost in a cataclysm.

 Color

“Valyrian steel had a darkness to it, a smokiness in its soul.” FfC

Valyrian steel is always described as being inescapably dark. Through heat treatment and chemical coatings, steel can be made to be black, blue, purple and a host of other hues. However, those are all surface treatments. That color can always be polished away and the steel beneath buffed up to a bright grey.

This, along with the difficulty in finding a steel that can match all of the qualities ascribed to Valyrian steel, makes me pretty convinced that it isn’t steel at all.

What else can it be?

Other Options

“Longclaw had been forged in the fires of old Valyria, forged in dragonflame and set with spells. Dragon-steel, Sam called it. Stronger than any common steel, lighter, harder, sharper.” DwD

At this point, I think that there are three possibilities for what Velerian steel is. The first is that Valyrian steel is magic. This is boring, so I won’t discuss it further. The second is that it is a very good pattern welded steel, and that the rest of the steel made in Westeros is such crap, that it seems like magic in comparison.The last is that it is not steel at all. If that is the case, then what else could it be?

One possible candidate is that Valyrian steel is a metal matrix composite, or MMC. These employ a metallic framework, which provides some toughness and tensile strength to the material, and have a much harder material, like a ceramic, embedded into them which could provide that indelible edge.

These are often incredibly difficult to make, requiring vacuum chambers, enormous pressures and temperatures, vaporized metals and extremely careful chemistry. The stuff only a wizard can do.

Something like a titanium/silicon-carbide composite could be a match for Valyrian steel. It would feel a lot like steel to touch, but would be darker and happily handle heats that would melt steel. It could be so hard that it would hold an edge extremely well, and if the metal matrix wasn’t perfectly consistent, there could be swirls of varied shades of grey running through the blade.

This seems like a pretty good solution, I’m not positive that it’s a perfect match, though. At the moment, this stuff is still in development for use in things like jet turbine blades and has a price tag over $1000 a pound, so I don’t know that anyone has tried to tailor it for medieval combat applications yet.

Glossary

GoT – A Game of Thrones
CoK – A Clash of Kings
SoS – A Storm of Swords
FfC – A Feast for Crows
DwD – A Dance With Dragons