page_title: Ferrous metallurgy
section_title: Industrial steelmaking
hierarchical_section_title: Ferrous metallurgy / Industrial steelmaking
context_page_description: Ferrous metallurgy is the metallurgy of iron and alloys. It began far back in prehistory. The earliest surviving iron artifacts, from the 4th millennium BC in Egypt, were made from meteoritic iron-nickel. It is not known when or where the smelting of iron from ores began, but by the end of the 2nd millennium BC iron was being produced from iron ores from at least Greece to India, and more controversially Sub-Saharan Africa. The use of wrought iron was known by the 1st millennium BC, and its spread marked the Iron Age. During the medieval period, means were found in Europe of producing wrought iron from cast iron using finery forges. For all these processes, charcoal was required as fuel.
  By the 4th century BC Wootz steel was being exported from India to ancient China, Africa, the Middle East and Europe. Archaeological evidence of cast iron appears in 5th-century BC China. New methods of producing it by carburizing bars of iron in the cementation process were devised in the 17th century.
context_section_description: Apart from some production of puddled steel, English steel continued to be made by the cementation process, sometimes followed by remelting to produce crucible steel.  These were batch-based processes whose raw material was bar iron, particularly Swedish oregrounds iron.
  The problem of mass-producing cheap steel was solved in 1855 by Henry Bessemer, with the introduction of the Bessemer converter at his steelworks in Sheffield, England. (An early converter can still be seen at the city's Kelham Island Museum). In the Bessemer process, molten pig iron from the blast furnace was charged into a large crucible, and then air was blown through the molten iron from below, igniting the dissolved carbon from the coke. As the carbon burned off, the melting point of the mixture increased, but the heat from the burning carbon provided the extra energy needed to keep the mixture molten. After the carbon content in the melt had dropped to the desired level, the air draft was cut off: a typical Bessemer converter could convert a 25-ton batch of pig iron to steel in half an hour.
  Finally, the basic oxygen process was introduced at the Voest-Alpine works in 1952; a modification of the basic Bessemer process, it lances oxygen from above the steel (instead of bubbling air from below), reducing the amount of nitrogen uptake into the steel. The basic oxygen process is used in all modern steelworks; the last Bessemer converter in the U.S. was retired in 1968. Furthermore, the last three decades have seen a massive increase in the mini-mill business, where scrap steel only is melted with an electric arc furnace. These mills only produced bar products at first, but have since expanded into flat and heavy products, once the exclusive domain of the integrated steelworks.
  Until these 19th-century developments, steel was an expensive commodity and only used for a limited number of purposes where a particularly hard or flexible metal was needed, as in the cutting edges of tools and springs.  The widespread availability of inexpensive steel powered the Second Industrial Revolution and modern society as we know it.  Mild steel ultimately replaced wrought iron for almost all purposes, and wrought iron is no longer commercially produced.  With minor exceptions, alloy steels only began to be made in the late 19th century.  Stainless steel was developed on the eve of World War I and was not widely used until the 1920s.
caption: Schematic drawing of a Bessemer converter
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