Ancient Steels


The information on this page is lifted straight from Wikipaedia. It's a great public source and you can learn alot just following links through their pages. I"ll add to it as I come up "new" types of ancient steels.

Crucible Steel

Crucible steel is steel made by melting pig iron (cast iron), iron, and sometimes steel, often along with sand, glass, ashes, and other fluxes, in a crucible. In ancient times steel and iron were impossible to melt using charcoal or coal fires, which could not produce temperatures high enough. However, pig iron, having a higher carbon content thus a lower melting point, could be melted, and by soaking wrought iron or steel in the liquid pig-iron for long periods of time, the carbon content of the pig iron could be reduced as it slowly diffused into the iron. Crucible steel of this type was produced in South and Central Asia during the medieval era. This generally produced a very hard steel, but also a composite steel that was inhomogeneous, consisting of a very high-carbon steel (formerly the pig-iron) and a lower-carbon steel (formerly the wrought iron). This often resulted in an intricate pattern when the steel was forged, filed or polished, with possibly the most well-known examples coming from the wootz steel used in Damascus swords. Due to the use of fluxes the steel was often much higher in quality (lacking impurities) and in carbon content compared to other methods of steel production of the time.

Techniques for production of high quality steel were developed by Benjamin Huntsman in England in the 18th century. Huntsman used coke rather than coal or charcoal, achieving temperatures high enough to melt steel and dissolve iron. Huntsman's process differed from some of the wootz processes in that it took a longer time to melt the steel and to cool it down and allowed more time for the diffusion of carbon.[1] Huntsman's process used iron and steel as raw materials, in the form of blister steel, rather than direct conversion from cast iron as in puddling or the later Bessemer process. The ability to fully melt the steel removed any inhomogeneities in the steel, allowing the carbon to dissolve evenly into the liquid steel and negating the prior need for extensive blacksmithing in an attempt to achieve the same result. Similarly, it allowed steel to simply be poured into molds, or cast, for the first time. The homogeneous crystal structure of this cast steel improved its strength and hardness compared to preceding forms of steel. The use of fluxes allowed nearly complete extraction of impurities from the liquid, which could then simply float to the top for removal. This produced the first steel of modern quality, providing a means of efficiently changing excess wrought iron into useful steel. Huntsman's process greatly increased the European output of quality steel suitable for use in items like knives, tools, and machinery, helping to pave the way for the Industrial revolution.

Wootz Steel

Wootz steel originated in India.[1][2] There are several ancient Tamil, Greek, Chinese and Roman literary references to high carbon Indian steel. The crucible steel production process started in the 6th century BC,[citation needed] at production sites of Kodumanal in Tamil Nadu, Golconda in Telangana, Karnataka and Sri Lanka and exported globally; the Tamils of the Chera Dynasty producing what was termed the finest steel in the world, i.e. Seric Iron to the Romans, Egyptians, Chinese and Arabs by 500 BC. The steel was exported as cakes of steely iron that came to be known as "Wootz". Wootz steel in India had high amount of carbon in it.

The Tamilakam method was to heat black magnetite ore in the presence of carbon in a sealed clay crucible inside a charcoal furnace. An alternative was to smelt the ore first to give wrought iron, then heat and hammer it to remove slag. The carbon source was bamboo and leaves from plants such as Avārai.[6][7] The Chinese and locals in Sri Lanka adopted the production methods of creating wootz steel from the Chera Tamils by the 5th century BC.[8][9] In Sri Lanka, this early steel-making method employed a unique wind furnace, driven by the monsoon winds. Production sites from antiquity have emerged, in places such as Anuradhapura, Tissamaharama and Samanalawewa, as well as imported artifacts of ancient iron and steel from Kodumanal. A 200 BC Tamil trade guild in Tissamaharama, in the South East of Sri Lanka, brought with them some of the oldest iron and steel artifacts and production processes to the island from the classical period.

The Arabs introduced the South Indian/Sri Lankan wootz steel to Damascus, where an industry developed for making weapons of this steel. The 12th century Arab traveler Edrisi mentioned the "Hinduwani" or Indian steel as the best in the world. Arab accounts also point to the fame of 'Teling' steel, which can be taken to refer to the region of Telengana. Golconda region of Telangana clearly being nodal centre for the export of wootz steel to West Asia.

Another sign of its reputation is seen in a Persian phrase – to give an "Indian answer", meaning "a cut with an Indian sword". Wootz steel was widely exported and traded throughout ancient Europe and the Arab world, and became particularly famous in the Middle East.

Damascus Steel

Damascus steel was the forged steel comprising the blades of swords smithed in the Near East from ingots of wootz steel.[1] These swords are characterized by distinctive patterns of banding and mottling reminiscent of flowing water. Such blades were reputed to be tough, resistant to shattering, and capable of being honed to a sharp, resilient edge.[2]

The steel is named after Damascus, the capital city of Syria. 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 original method of producing wootz is not known. Modern attempts to duplicate the metal have not been entirely successful due to differences in raw materials and manufacturing techniques. Several individuals in modern times have claimed that they have rediscovered the methods by which the original Damascus steel was produced.

The reputation and history of Damascus steel has 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.

Noric Steel

Noric steel was a steel from Noricum, a Celtic kingdom located in modern Austria and Slovenia.

The proverbial hardness of Noric steel is expressed by Ovid: "...durior [...] ferro quod noricus excoquit ignis..." which roughly translates to "...harder than iron tempered by Noric fire [was Anaxarete towards the advances of Iphis]..."[1] and it was widely used for the weapons of the Roman military after Noricum joined the empire in 16 BC.

The iron ore was quarried at two mountains in modern Austria still called Erzberg "ore mountain" today, one at Hüttenberg, Carinthia and the other at Eisenerz, Styria, separated by c. 70 km. The latter is the site of the modern Erzberg mine.

Buchwald identifies a sword of c. 300 BC found in Krenovica, Moravia as an early example of Noric steel due to a chemical composition consistent with Erzberg ore. A more recent sword, dating to c. 100 BC and found in Zemplin, eastern Slovakia, is of extraordinary length for the period (95 cm, 37 in) and carries a stamped Latin inscription (?V?TILICI?O), identified as a "fine sword of Noric steel" by Buchwald. A center of manufacture was at Magdalensberg.

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