Damascus steel
Damascus steel (Arabic: فولاذ دمشقي) refers to the high carbon crucible steel of the blades of historical swords forged using the wootz process in the Near East, characterized by distinctive patterns of banding and mottling reminiscent of flowing water, sometimes in a "ladder" or "rose" pattern.
"Damascus steel" developed a high reputation for being tough, resistant to shattering, and capable of being honed to a sharp, resilient edge.
Modern steelmakers and metallurgists have studied it extensively, developing theories on how it was produced, and significant advances have been made.
Damascus blades were first manufactured in the Near East from ingots of wootz steel that were imported from Southern India (present-day Telangana Tamil Nadu and Kerala).
Bin iron is produced in Persia [Bosi 波斯]; it is so hard and sharp that it can cut gold and jade ... [The last two kinds come from Shanxi and the Southwest.
Extant examples of patterned crucible steel swords were often tempered in such a way as to retain a bend after being flexed past their elastic limit.
[19][20] A misconception that the steel was hardened by thrusting it six times in the back and thighs of a slave originated in an article in the November 4, 1894 issue of the Chicago Tribune titled Tempering Damascus Blades.
[23] This effect is likely due to the thinning and refinement of the microstructure, and to achieve optimal properties, the steel should be folded a few hundred times.
[27]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.
A research team in Germany published a report in 2006 revealing nanowires and carbon nanotubes in a blade forged from Damascus steel,[32][29][33] although John Verhoeven of Iowa State University in Ames suggests that the research team which reported nanowires in crucible steel was seeing cementite, which can itself exist as rods, so there might not be any carbon nanotubes in the rod-like structure.
[34] Production of these patterned swords gradually declined, ceasing by around 1900, with the last account being from 1903 in Sri Lanka documented by Coomaraswamy.
Several modern theories have ventured to explain this decline: The discovery of alleged carbon nanotubes in the Damascus steel's composition, if true, could support the hypothesis that wootz production was halted due to a loss of ore sources or technical knowledge, since the precipitation of carbon nanotubes probably resulted from a specific process that may be difficult to replicate should the production technique or raw materials used be significantly altered.
[34] Modern attempts to duplicate the metal have not always been entirely successful due to differences in raw materials and manufacturing techniques, but several individuals in modern times have successfully produced pattern forming hypereutectoid crucible steel with visible carbide banding on the surface, consistent with original Damascus Steel.
[44] J. D. Verhoeven and A. H. Pendray published an article on their attempts[45] to reproduce the elemental, structural, and visual characteristics of Damascus steel.
A subsequent lower-temperature heat treatment, at a temperature at which the carbides were again stable, could recover the structure by the binding of carbon by those elements and causing the segregation of cementite spheroids to those locations.
In Russia, chronicles record the use of a material known as bulat steel to make highly valued weapons, including swords, knives, and axes.
The exact origin or the manufacturing process of the bulat is unknown, but it was likely imported to Russia via Persia and Turkestan, and it was similar and possibly the same as Damascus steel.
A team of researchers based at the Technical University of Dresden that used x-rays and electron microscopy to examine Damascus steel discovered the presence of cementite nanowires[47] and carbon nanotubes.
[49] The resulting samples exhibited superior mechanical properties to ancient Damascus steels, with a tensile strength of 1300 MPa and 10% elongation.
Prior to the early 20th century, all shotgun barrels were forged by heating narrow strips of iron and steel and shaping them around a mandrel.
[50][51] These types of barrels earned a reputation for weakness and were never meant to be used with modern smokeless powder, or any kind of moderately powerful explosive.
