Wootz steel

Wootz steel is a crucible steel characterized by a pattern of bands, which are formed by sheets of micro carbides within a tempered martensite or pearlite matrix in higher carbon steel, or by ferrite and pearlite banding in lower carbon steels. It is the pioneering steel alloy matrix developed in Southern India in the 6th century BC and exported globally. It was also known in the ancient world by many different names including Wootz, Ukku, Hindvi Steel, Hinduwani Steel, Teling Steel and Seric Iron.

Wootz steel originated in India. There are several ancient Tamil, Greek, Chinese and Roman literary references to high carbon Indian steel since the time of Alexander's India campaign. The crucible steel production process started in the 6th century BC, 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."

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 heated and hammered to be rid of slag. The carbon source was bamboo and leaves from plants such as Avārai. The Chinese and locals in Sri Lanka adopted the production methods of creating wootz steel from the Chera Tamils by the 5th century BC. 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.

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