Damascus steel was the forged steel comprising the blades of swords smithed in the Near East from ingots of Wootz steel imported from India and Sri Lanka. These swords are characterized by distinctive patterns of banding and mottling reminiscent of flowing water, or in a "ladder" or "teardrop" pattern. Such blades were reputed to be tough, resistant to shattering, and capable of being honed to a sharp, resilient edge.
Close-up of an 18th-century Persian-forged Damascus steel sword.
The Arabs introduced the wootz steel to Damascus, where a weapons industry thrived. From the 3rd century to the 17th century, steel ingots were being shipped to the Middle East from India.
The steel is named after Damascus, the capital city of Syria and one of the largest cities in the ancient Levant. It may either refer to swords made or sold in Damascus directly, or it may just refer to the aspect of the typical patterns, by comparison with Damask fabrics (which are themselves named after Damascus).
The reputation and history of Damascus steel have given rise to many legends, such as the ability to cut through a rifle barrel or to cut a hair falling across the blade. A research team in Germany published a report in 2006 revealing nanowires and carbon nanotubes in a blade forged from Damascus steel. Although many types of modern steel outperform ancient Damascus alloys, chemical reactions in the production process made the blades extraordinary for their time, as Damascus steel was superplastic and very hard at the same time.
During the smelting process to obtain Wootz steel ingots, woody biomass and leaves are known to have been used as carburizing additives along with certain specific types of iron-rich in microalloying elements. These ingots would then be further forged and worked into Damascus steel blades. Research now shows that carbon nanotubes can be derived from plant fibers, suggesting how the nanotubes were formed in the steel. Some experts expect to discover such nanotubes in more relics as they are analyzed more closely.
When did Damascus steel appear for the first time?
Let's look at were the Wootz steel first started; India. There a huge Iron pillar of Delhi which is standing at 23 feet 8 inches high (7.2 metres) with 16 inches diameter. It is believed to have been constructed in the third or fourth century B.C by "King Chandra", probably Chandragupta II, and is currently standing in the Qutb complex at Mehrauli in Delhi, India. It is famous for the rust-resistant composition of the metals used in its construction.
Scientific research carried out on the “iron pillar of Delhi” unveiled a surprising fact – it is made of forging steel! (not alloy steel).
Iron pillar of Delhi.
The Indian steel manufacturing method has been appreciated since a very long time ago. Round chisels made of steel and another steel objects were unearthed in the old graves close to Wurre Gaon in Kamptee, which is thought to have been made around 1500 B.C (some estimate around 600 B.C). It means that these steel objects had already been manufactured a couple of centuries before the period when “iron pillar of Delhi” was established.
“Damascus steel” was known as appropriate for a blade not for a pillar. The following are examples often cited to signify quality and sharpness of Damascus blade: “If a silk scarf drops on a Damascus blade with its edge up, the scarf will be cut into two pieces in a second due only to its weight.” “Damascus blades are never chipped even if they are used to cut iron armor.” “It’s so resilient as if it were a willow branch. It won’t break even if it’s bent. It takes only a second for it to go back to its original state – release a blade, and you will notice that it immediately goes back to the same as it was again.”
All of them sounds a bit exaggerated but describe exactly what “Damascus steel” is all about. Not only its quality as a blade but also its mystery - its strength, unique pattern on its surface and rust-proof property- are the main reasons to make the above examples sound plausible.
In the Crusader period, Damascus swords attained an unparalleled reputation and had been passed down as an heirloom of royal families. Also, the Crusaders were proud of having a Damascus sword. The recent study found that the secret to a sharp, rust-proof and resilient feature of Damascus blade lies in the manufacturing process where its specific pattern is formed.
, Wikipedia : Damascus steel
 Wikipedia : Iron pillar of Delhi