Ancient Indian steel hid nanostructures that modern researchers finally decoded
By around 200 BCE smiths in southern India were making an ultra-high carbon steel in crucibles. Rome imported it as Seric Iron, and Europe later knew blades made from it as Damascus steel. Traces of vanadium in the local ore helped form nanoscale structures inside the metal, giving it remarkable hardness and an unusual ability to stretch.
That steel, called wootz or Golconda steel, puzzled people for centuries. Professor J. D. Verhoeven and the bladesmith Al Pendray eventually cracked it by showing how impurities in the original ore encouraged carbides to form, and how repeated heating and cooling of the blade created the famous rippling pattern. Their reproductions match ancient blades both to the eye and under the microscope. Tamil literature and archaeology suggest the technique was established in south India well before the common era.
Metallurgy is the science beneath the craft of metalworking, rather as medical science underpins medicine. Its name comes from Greek words for mine and work, and it began as an alchemist's term for pulling metal out of minerals. Today it splits into chemical metallurgy, dealing with extraction, electrochemistry and corrosion, and physical metallurgy, dealing with crystal structure, strength and how parts fail. Iron-based production dominates overwhelmingly, making up 95 percent of all metal produced worldwide.
Gold came first because it turns up pure in nature; flecks in Spanish caves date back some 40,000 years. Smelting, heating ore to free the metal, appears earliest in the Balkans and Carpathians, where a smelted copper axe from Plocnik in Serbia dates to about 5,500 BCE. That region, home to cultures such as Vinca and Varna, has been called the earliest metallurgical province in Eurasia, and the Varna burial ground in Bulgaria holds the world's oldest gold treasure. Bronze, made by mixing copper with tin, appeared in the Near East around 3,500 BCE. Iron was harder to extract, and the Hittites seem to have mastered it about 1,200 BCE.
Georg Agricola's sixteenth-century book De re metallica set out the mining and smelting methods of his day in such detail that he is often called the father of metallurgy. Modern metallurgists pick alloys to suit a job: aluminium and magnesium for light aircraft and car parts, nickel superalloys such as Inconel for the heat inside gas turbines, and single crystal alloys that resist slow deformation at extreme temperatures.
Source: Metallurgy
