The Mystery of the Damascus Sword

John Verhoeven and Alfred Pendray and Diana Lutz
Muse

Dec 31, 2006 19:00 EST

Before atom bombs and chemical warfare, before jet fighters and tanks, even before guns and cannons, people fought with swords. Swords were one of the main weapons of war for centuries. And for that reason, good strong swords were highly valued. A dependable sword could save your life. What would happen if your sword broke in the middle of a fight? Or if it wasn't sharp enough? You'd probably end up dead. So good swords were highly prized. And just like there are certain types of cars that are known to be very fast (and even brands of sneakers that are supposed to give you an edge), there was one kind of sword that everyone wanted. It was made in Damascus, a city in Syria, and so was called a Damascus sword. Western Europeans first saw these swords in the hands of Muslim warriors a thousand years ago. Today you can see examples of Damascus swords hanging in the arms and armor sections of most large museums.

Damascus swords were prized for their strength and sharpness. They were famous for being so sharp that they could cut a silk scarf in half as it fell to the ground, something European swords couldn't do. They were also known for their beauty. The surface of a Damascus blade has a wavy pattern on it that looks a little like wood grain. Sometimes the wavy pattern would form lines across the sword that looked like the rungs of a ladder; this was called Mohammed's ladder. Sometimes the waves formed circular swirls called roses. And unless you had the wavy pattern on your blade, you didn't have a true Damascus sword.

Nor only were Damascus swords sharp and beautiful, they were also objects of mystery. The best European bladesmiths from the Middle Ages on up weren't able to make them, even though they carefully studied examples of blades made in the East. Damascus blades became even more mysterious when the art of making them actually died out. The last Damascus swords were made in the early 1800s.

Over the years, metallurgists (people who study metals) have suggested many different ways of making the swords, but when they were tested, none of the methods made blades that matched the Damascus swords in the museums. The recipe for a Damascus sword was a puzzle that challenged people for centuries. With all the knowledge and technological advances of the 20th century, people still couldn't figure out how to make these swords. What was the secret?

I'm a metallurgist who teaches about metals at Iowa State University. I became interested in Damascus swords when I read an article about them that one of my students gave me. Alfred Pendray, my coauthor, is a bladesmith in Williston, Florida, who also became interested in the swords by reading about them. We worked on the problem independently, until a mutual friend put us in touch. For a year, we wrote back and forth, and in 1989 we finally met and decided to try to solve the mystery together. At first, we tried methods for making Damascus swords that had been published in science journals. But those methods didn't give us blades that matched the old blades. So we decided to go back to the very beginning. We would trace step by step how the swords were made in ancient times and see if we could figure out how the ancient craftsmen did it.

According to reports of travelers to the East, the swords were made by forging small cakes of steel that were manufactured in southern India. This steel was called wootz steel. Wootz steel first appeared in India sometime between 300 BC and AD 500. It was more than a thousand years before steel as good was made in the West. Wootz was the first high-quality steel made anywhere in the world.

Steel is a mixture of iron and carbon. To make wootz steel, the craftsmen melted iron and materials that contain carbon, such as charcoal, wood, or leaves. They did this in a sealed crucible, which is simply a melting pot able to withstand high temperatures. When the cooled and hardened steel was taken out of the crucible, it was in the shape of a cake. The wootz cakes (which were about the size of hockey pucks and weighed about four pounds) were then shipped to Damascus, where smiths made them into beautiful blades.

To shape the cake into a blade, the smiths repeatedly heated and hammered it until it was stretched and flattened into a blade shape. As the metal was heated and beaten, the wavy pattern somehow formed on the surface of the blade.

One of the major problems we faced in making a Damascus sword was to get the right pattern on the surface. And in order to get the right pattern on the outside of the sword, you had to have the right structure inside the sword. In steel, some carbon chemically combines with iron to form a new kind of chemical called iron carbide. These iron carbide particles are surrounded by metal that is almost pure iron. But it is the arrangement of these carbide particles that causes the famous Damascus pattern.

The interesting thing is that the carbide particles aren't scattered randomly throughout the Damascus blade. If you sawed the sword blade in half and looked at the cut surface under a microscope, you'd see how the carbide particles arrange themselves in rows. This is called banding. These bands of carbide particles form the pattern you see on Damascus swords. When the steel is beaten with a rounded hammer, the bands of carbide particles near the surface are pushed up and down until they look like waves instead of bands.

The wavy pattern in true Damascus blades only turns up during the beating and hammering of the steel cake into a blade. No one could figure out how this pattern was formed. People tried to create the pattern in many ways. Smiths tried to copy the pattern by etching or carving the metal. They also tried welding different types of steels together to create a patterned look. And some of the patterns they created were beautiful. But if you looked closely, you could see the surfaces of these objects didn't really look like the surfaces of true Damascus blades. And since they didn't have the right pattern, they didn't have the right structure on the inside either.

So what caused the pattern to appear? We guessed that impurities in the steel might have something to do with the carbide banding. In plain steel, any element that isn't carbon or iron is an impurity. By today's standards, cooking steel in a crucible is a dirty process; the finished steel is likely to contain small amounts of many different impurities from the iron ore or from the walls of the crucible. Perhaps there was a special impurity in Damascus steel that made the pattern.

But what kind of impurities did Damascus steel have? In the past 100 years, scientists have analyzed the ingredients of 10 Damascus blades, and these analyses have shown that wootz steel contains small amounts of four impurity elements: sulfur, phosphorous, silicon, and manganese. So why couldn't people recreate a Damascus blade if they had the recipe and knew how the steel was prepared? Well, we guessed that there might have been other impurity elements in the steel that people missed. The impurities could have been present in such small amounts that they were undetectable. Nowadays we can analyze elements at lower levels than before, so we thought there was a chance that we might not have all the right ingredients.

Was our guess about the impurities right? Only trying to make a blade would tell. Although our early attempts to make Damascus steel mostly failed, once in a while we succeeded in making a presentable Damascus blade. Like cooks perfecting a recipe, we started to experiment with our ingredients, adding different amounts of impurities and carefully watching and controlling the heating of the metal.

Our big break came when we started to make our steel using a type of commercial iron called Sorel iron, which is refined from a special ore deposit in Canada. Once we started using this iron we began to obtain much better results. We analyzed it and found very small amounts of two carbideforming elements called titanium and vanadium. When these two elements were present, we got improved results. Eventually we got to the point where we could make Damascus steel that could he forged into good blades on nearly every try. So to get an internal structure consisting of bands of carbide particles, the steel had to contain small amounts of vanadium and titaniumbut, as we found out, particularly vanadium.

Genuine Damascus blades are considered treasures, so their owners usually don't allow metallurgists to cut them up. You can imagine how excited we were when a museum in Switzerland recently gave us small pieces of several original blades for study. We found that they all contained very small amounts of vanadium. This agrees with our discovery that vanadium is a key impurity element for making Damascus steel.

There are still things we don't understand about Damascus steel. For example, despite all our science, we still don't know why vanadium makes the carbide particles line up in rows when other impurities do not. But our method has passed the crucial practical test: we are now consistently able to make blades that have both the external surface patterns and the internal structure of ancient Damascus blades. And, yes, our blades can cut a silk scarf in half as it falls to the ground.

Our solution to the puzzle also suggests an answer to an interesting historical question: why was this art lost in the first place? The answer may be that only certain deposits of iron ore in India contained the necessary impurities. When these ore deposits were used up, and when bladesmiths began to use steel from other areas of India, the secret ingredients were missing, the magic was lost, and with it, the secret of Damascus steel.

© 2007 Carus Publishing Company Provided by ProQuest LLC. All Rights Reserved.

Source: Muse

 

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