The general term “Damascus” refers to metal with a visible grain pattern, sometimes with a texture. Modern Damascus is a lamination of folded steels selected with cosmetic qualities, with grinding and polishing specifically to expose the layers. True Damascus patterns are formed when carbon trace elements form visible swirls in the steel mix. These elements change properties when the steel is work hardened (forged), creating the patterns.
Damascus steel is a hot-forged steel used in Middle Eastern sword making from about 1100 to 1700 AD. Damascus swords were of legendary sharpness and strength, and were apocryphally claimed to be able to cut through lesser quality swords and even rock. The technique used to create original Damascus steel is now a matter of historical conjecture. Many raw materials and the metal smiths’ recipes are no longer available. The foundation for Damascus Steel is Wootz Steel, which originated in India and Sri Lanka then later spread to Persia. From the 3rd century to 17th century, India was shipping steel ingots to the Middle East for use in Damascus steel which makes great swords and hunting knives.
The most popular theory of Damascus steel was premised on pattern welding because the layering revealed by etching a pattern-welded blade in acid is similar to that of Damascus steel. Hence, pattern welded steel is commonly sold today as “Damascus steel” even though recent research suggests the original Damascus steel was created with a different technique.
Pattern welded Damascus is made from several types of steel and iron slices, which are then welded together to form a billet. The patterns vary depending on how the smith works the billet. The billet is drawn out and folded until the desired number of layers are formed. The end result can bear a strong resemblance to the surface appearance of a true Damascus blade although the internal structure is dissimilar.
Several other steel making techniques, such as wootz steel also result in patterned surfaces and have often been sold as Damascus steel, Damascened steel and sometimes watered steel. The most common technique today for producing these materials is pattern welding, which is widely used for custom knife making. Modern Damascus steel is usually made by pattern welding two tool steels, one with high nickel content, appearing bright, the other appearing more grey so that alternating steels produce light-dark stripes. Treating or pickling the steel with dilute acid after polishing enhances the pattern by darkening one of the steels more than the other. Folding and twisting while hammer forging controls the striped pattern, and the method used is often trademarked. Skilled swordsmiths can manipulate the layered patterns to mimic the complex designs found in the surface of the original, medieval Damascus steel. Some knife artists begin with stacking steel wires and through folding can produce repeating images along a blade, such as a crossed U.S. flags. Stacking wires is a speciality of the Cable Damascus technique, a new age development. The advent of steel wire rope (1830’s) provided mid-west blacksmiths a way to make corn harvester’s machetes (cable knives).
One explanation of the legendary properties of Damascus steel is that the pattern consists of alternating bands of very hard, but brittle iron carbide or cementite and softer more flexible iron. Another possibility is that the steel contains a small amount of vanadium, which would theoretically strengthen the blade . The legendary steel may have been a happy accident by way of the limited production methods. Original Damascus steel billet was formed from a small disk that was hammer folded/forged into its final shape. Unlike northern European methods, the ferro-smelting technique in Persia during the Middle Ages involved small bowl-type crucibles with lids, baked in a mound-type oven often used for bread. Controlling the air contact to the melt, as well as trace elements found locally, all combined to produce a steel blade noticeably better than its contemporaries.
Carbon nanotubes and nanowires were found in a sample of a 17th century sword forged from Damascus steel. The complex process of forging and annealing is thought to have accounted for the nano-scale structures.
The origins of the name Damascus remains somewhat controversial. Damascus steel was originally made using ore with a certain chemical composition from a mine that is now exhausted, so attempts at reproduction are difficult at best.
It would seem obvious that the name Damascus refers to swords forged in Damascus, but there are several other possible sources of the name. One is the name of the swordsmith himself: the author al-Beruni refers to swords made by a man he names Damashqi