Орта Шығыс қылыштарында қолданылған болат түрлері

Type of steel used in Middle Eastern swordmaking

Damascus steel (Arabic: فولاذ دمشقي) is the forged steel of the blades of swords smithed in the Near East from ingots of carbon steel imported from Southern India or made in production centers in Sri Lanka or Khorasan, Iran. These swords are characterized by distinctive patterns of banding and mottling reminiscent of flowing water, sometimes in a "ladder" or "rose" pattern. Such blades were reputed to be tough, resistant to shattering, and capable of being honed to a sharp, resilient edge. Wootz (Indian), Pulad (Persian), Fuladh (Arabic), Bulat (Russian), and Bintie (Chinese) are all names for historical ultra high carbon crucible steel typified by carbide segregation. "Wootz" is an erroneous transliteration of "utsa" or "fountain" in Sanskrit; however, since 1794, it has been the primary word used to refer to historical hypereutectoid crucible steel. The term "Damascus steel" itself likely traces its roots to the medieval city of Damascus, Syria.

Many claim that modern attempts to duplicate the metal have not been entirely successful due to differences in raw materials and manufacturing techniques. However, 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. Production of these patterned swords gradually declined, ceasing by around 1900, with the last account being from 1903 in Sri Lanka documented by Coomaraswamy. or a combination of all the above. In addition to being made into blades in India (particularly Golconda) and Sri Lanka, wootz / ukku was exported as ingots to various production centers, including Khorasan, and Isfahan, where the steel was used to produce blades, as well as across the Middle East. Al Kindi states that crucible steel was also made in Khorasan in addition to steel that was imported. The discovery of carbon nanotubes in the Damascus steel's composition supports 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. Pattern welded steel has been referred to as "Damascus steel" since 1973 when Bladesmith William F. Moran unveiled his "Damascus knives" at the Knifemakers' Guild Show. This "Modern Damascus" is made from several types of steel and iron slices welded together to form a billet, and currently, the term "Damascus" (although technically incorrect) is widely accepted to describe modern pattern welded steel blades in the trade. The patterns vary depending on how the smith works the billet.

J. D. Verhoeven and A. H. Pendray published an article on their attempts to reproduce the elemental, structural, and visual characteristics of Damascus steel. They found that certain carbide forming elements, one of which was vanadium, did not disperse until the steel reached higher temperatures than those needed to dissolve the carbides. Therefore, a high heat treatment could remove the visual evidence of patterning associated with carbides but did not remove the underlying patterning of the carbide forming elements; 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. Thermal cycling after forging allows for the aggregation of carbon onto these carbide formers, as carbon migrates much more rapidly than the carbide formers. Progressive thermal cycling leads to the coarsening of the cementite spheroids via Ostwald ripening.

In Russia, chronicles record the use of a material known as bulat steel to make highly valued weapons, including swords, knives, and axes. Tsar Michael of Russia reportedly had a bulat helmet made for him in 1621. 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. Pavel Petrovich Anosov successfully reproduced the process in the mid 19th century. Wadsworth and Sherby also researched the reproduction of bulat steel and published their results in 1980.

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 and carbon nanotubes. German researchers have investigated the possibility of manufacturing high strength Damascus steel through laser additive manufacturing techniques as opposed to the traditional folding and forging. 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. This process was referred to as "laminating" or "Damascus".

Verhoeven, Peterson, and Baker completed mechanical characterization of a Damascus sword, performing tensile testing as well as hardness testing. They found that the Damascus steel was somewhat comparable to hot rolled steel bars with 1.0 wt% carbon with regards to mechanical properties. The average yield strength of 740 MPa was higher than the hot rolled steel yield strength of 550 MPa, and the average tensile strength of 1070 MPa was higher than the hot rolled steel tensile strength of 965 MPa. These results are likely due to the finer pearlite spacing in the Damascus steel, refining the microstructure. The elongation and reduction in area were also slightly higher than the hot rolled steel averages. Rockwell hardness measurements of the Damascus steel ranged from 62 67. These mechanical properties were consistent with the expected properties from the constituent steels of the material, falling between the upper and lower bounds created by the original steels. Another study investigated the properties of Damascus steel produced from 1075 steel and 15N20 steel, which have approximately equal amounts of carbon, but the 15N20 steel notably has 2 wt% nickel. The 1075 steel is known for high strength, but low toughness, with a pearlitic microstructure, and the 15N20 steel is known for high toughness with a ferritic microstructure. The mechanical properties of the resultant laminate Damascus steel were characterized, in samples with 54 folds in production as well as samples with 250 folds. Charpy V notch impact tests showed that the 54 fold samples had an impact toughness of 4.36 J/cm2, while the 250 fold samples had an impact toughness of 5.49 J/cm2. Tensile testing showed that yield strengths and elongations for both samples were similar, at around 475 MPa and 3.2% respectively. However, the maximum strength of the 54 fold samples was notably lower than that of the 250 fold samples (750 MPa vs. 860 MPa). This study showed that the folding process has a significant impact on the mechanical properties of the steel, with increasing toughness as fold numbers increase. They also compare mechanical properties of the Damascus to the original materials, finding that the properties of the Damascus steel lie in between those of the two constituent steels, which is consistent with composite material properties. The processing and design of the laminations and bands can have a significant effect on mechanical properties as well. Regardless of tempering temperature and the liquid the steel is quenched in, the impact strength of Damascus steel where the impact is perpendicular to the band orientation is significantly higher than the impact strength where the impact is parallel to the band orientation. This is due to the failure and fracture mechanisms in Damascus steel, where cracks propagate fastest along the interfaces between the two constituent steels. When impact is directed parallel to the bands, cracks are able to propagate easily along the lamination interfaces. When impact is directed perpendicular to the bands, the lamination interfaces are effectively protected, deflecting the cracks and increasing the energy required for cracks to propagate through the material. These results provide insight into optimal Damascus steel design depending on application: band orientation should be chosen to protect against deformation and increase toughness.

The blade that Beowulf used to kill Grendel's mother in the story Beowulf was described in some Modern English translations as "damascened". The exceptionally strong fictional Valyrian steel mentioned in George R. R. Martin's book series A Song of Ice and Fire, as well as its television adaptation Game of Thrones, appears to have been inspired by Damascus steel, but with a magic twist. Just like Damascus/Wootz steel, Valyrian steel also seems to be a lost art from an ancient civilization. Unlike Damascus steel, however, Valyrian steel blades require no maintenance and cannot be damaged through normal combat. A common misconception is that the steel was hardened by thrusting it six times in the back and thighs of a slave. This originated in an article on page 28 of the Chicago Tribune of November 4, 1894 titled Tempering Damascus Blades. The note asserts that a certain "Prof. von Eulenspiegel" found a scroll "among the ruins of ancient Tyre". "Eulenspiegel" is the name of the legendary prankster of medieval Germany.