GREG OLSON wants to forge the strongest sword in history, a sword that
will be known as Dragonslayer. He knows a good marketing ploy when he sees one.
The idea is to auction off the sword to collectors, to gain publicity for a new
type of steel called Ferrium C69. It鈥檚 the hardest steel ever made, perfect for
knives, aerospace engines and racing car components. And, according to Olson,
killing dragons too.
Olson, a materials scientist at Northwestern University in Evanston,
Illinois, has a serious point to prove. Modern steel-making, he says, relies on
methods discovered by trial and error. First you take iron ore and heat it with
lime, to remove impurities and load it with carbon. Then you start to cool it
down, hoping you鈥檝e got just the right amount of carbon to harden the metal
without making it too brittle.
While it is still warm, you hammer it into shape, and finally temper it by
reheating and cooling. That squeezes yet more carbon from the inside to the
outermost layers, making the outer shell extra hard while reducing the
brittleness of the core.
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But because today鈥檚 industrial steels rely on this traditional approach, they
are little better than the best steels of antiquity鈥擩apanese samurai
swords forged 500 years ago. Measured on a hardness scale called Rockwell C,
both achieve a rating of around 60. 鈥淭he mystique of samurai swords was that
they could cut through any other sword,鈥� says Olson. Not for much longer.
Olson, along with colleagues at Northwestern and a spin-off company called
QuesTek, have taken steel-making to the next level. They have spent 15 years
investigating how smelting, quenching and tempering squidgy iron turns it into
super-hard steel. They examined steel at scales from the atomic to the
crystalline, using X-rays, microscopes and computer models. Now they think
they鈥檝e figured out exactly how the structure of steel imparts hardness and
toughness.
Iron is soft because defects in its atomic structure can move around,
allowing the metal to deform. The steel-making process encourages microscopic
iron carbide crystals to form within the metal. These crystals are hard, and act
as bosses to stop defects from moving. Also the repeated heating and cooling of
steel pushes the defects out to the boundaries of each metal grain. And adding
other metals such as chromium, molybdenum and cobalt introduces more barriers to
the movement of defects.
Olson and his group now understand these processes in such detail that they
can design an alloy from scratch, honing its properties on a computer long
before the metal is forged. The trick, Olson says, is to make the iron carbide
crystals exactly the right size and pack them into the metal as close to one
another as possible. The ideal crystal size is 3 nanometres and the
metal-to-carbide ratio should be 2 to 1.
Ferrium C69 is the result. As its name suggests, it has a Rockwell C rating
of 69, far harder than today鈥檚 best steels and pushing the theoretical limits.
But hardness isn鈥檛 everything. C69 is also tough, because the hardest outer
layer is very thin, and therefore close to the flexible core. That鈥檚 ideal for
devices that suffer punishing wear and tear but need to be light, such as
aircraft and rocket engines. QuesTek is talking to dozens of potential
customers, including the Newman-Haas motor racing team, about possible
applications.
But Olson isn鈥檛 satisfied with that. He wants to turn potential customers
into paying customers. Enter Dragonslayer鈥攁 publicity stunt crafted as
carefully as the steel.
Last year Olson asked Richard Furrer, an amateur bladesmith in Wisconsin, to
forge a foot-long dagger from Ferrium C69. They tested it, blade-on-blade,
against a Japanese hunting knife forged in the same way as samurai swords. The
C69 dagger came out on top, gouging 6 millimetres into its rival.
The next move is to make a broadsword to sell at auction. But crafting
something that will attract bids isn鈥檛 just a matter of getting the steel right.
Sword collectors, Olson knows, also look for a dose of mythology.
European mythology abounds with tales of dragonslaying. But what turns a
sword into a dragonslayer? Olson needed some evidence of what properties are
most valuable. To get it, he turned to the Beowulf legend. Written around 1250
years ago, it tells the story of Beowulf, prince of the Geats, who travels to
Denmark to slay the man-eating monster Grendel. On his return, Beowulf rules for
50 peaceful years. Then a fire-breathing dragon invades his lands and Beowulf is
forced to take up arms. He confronts the dragon and smites it with his ancestral
sword, but the blade blunts on the dragon鈥檚 scales. Beowulf is mortally wounded
and his sword destroyed.
Beowulf鈥檚 sword would have been a pattern-welded broadsword, as hard as the
techniques of the day allowed. Clearly that wasn鈥檛 good enough. To penetrate the
dragon鈥檚 horny scales, he would have needed a harder steel, Olson says鈥攁
steel very much like Ferrium C69. Olson also claims that the heat and
corrosion-resistant properties of C69 would have helped it withstand the
dragon鈥檚 fiery breath and survive its acid blood.
In truth, the story only tells us Beowulf鈥檚 steel was too soft, not that C69
would be hard enough. But Olson thinks the evidence will be good enough to
entice collectors. So now he is looking for a professional swordsmith to forge
the blade. That leaves one final ingredient鈥攁 piece of the heavens.
The most famous of all swords, Excalibur, was said to derive its magical
powers from 鈥渟ky metal鈥�, or meteoritic iron. Olson wants Dragonslayer to be made
in the same way. He considered using iron from a 16th-century Chinese meteorite
called Nantan, which you can buy online for around $100 a kilogram, but
that wasn鈥檛 wholly satisfactory. 鈥淚鈥檇 prefer something from around Beowulf鈥檚
time,鈥� he says. 鈥淢aybe even a meteorite from outside the Solar System. It
depends on where they thought heaven was, since that鈥檚 where the metal
supposedly got its powers from. I might need some theological guidance on
迟丑补迟.鈥�
Dragonslayer is due to be auctioned at Christie鈥檚 in New York next year, but
after that you too will be able to get a piece of the heroic action. All you
need to do is take up cooking or golf. When the publicity is at its peak,
QuesTek plans to unleash Ferrium C69 on the general public. The first products
on the market will be chefs鈥� knives and golf clubs. The brand name to look out
for? Dragonslayer, of course.