The extreme strength, sharpness and resilience of swords made from Damascus steel has resulted in them being spoken of in the same tone as myths and legends. One story is that a Damascus sword can cut clean through rock and still remain sharp enough to cut through a silk scarf dropped on the blade. These swords are also known for an intricate wavy pattern etched on the sword and were wielded by the Islamic army during the crusades.
Many of these swords are still in existence but the technique for making them was lost during the 18th century.
We still don’t know how to make a Damascus steel sword but a paper published in the November 16th 2006 edition of Nature reveals some of the secrets behind the steel itself and points strongly to production methods. A team led by Peter Paufler of the Technical University of Dresden, Germany studied the metallurgical properties of a 17th century Damascus sword.
Nanowires and Carbon Nanotubes
They found that the sword contained nanowires and carbon nanotubes. This in itself is not surprising, carbon nanotubes and buckyballs are naturally formed in the fires of a blacksmiths forge and have been found in common steel previously. In this case the nanowires are cementite and are surrounded by the extremely strong carbon nanotubes. All of which is held within the much softer steel matrix.
Manufacturing A Damscus Sword
The thinking on how this unique steel becomes a Damascus sword may in turn hold the answer to how the sword gets it’s remarkable properties. During the forging process the metal within the sword may have been folded like an ancient Japanese samurai sword or it may be forged by a different process. Regardless of the forging method, the nanotube / nanowire particles end up aligned in layers with the layers separated by normal steel in a form of reinforced metal composite.
The nanotube / nanowire layers would contribute extreme strength to the steel and the softer steel would allow the sword to still remain resilient. Late in the manufacturing process the sword is etched with acid. This etching process removes steel from the surface of the blade revealing the intricate wavy lined pattern signature of a Damascus steel blade. The nanotubes are resistant to the acid and protect the cementite nanowires. With the steel removed from the cutting edge of the blade, the edge effectively becomes incredibly sharp and minutely serrated – and exceptionally difficult to make dull.