Steel is an alloy, i.e. a misch metal which is created by melting several materials together. Today there are more than 2,500 standard types of steel worldwide. All of them consist mainly of pig iron which, in turn, consists of the element iron and more then three percent carbon.

Pig iron is extracted from iron ore in blast furnaces. It is then processed in a steelworks to create steel with a carbon content of less than two percent. This low proportion makes the material softer, allowing it to be processed easily.

The development of the blast furnace in the 14th century made it possible: iron could be heated until it remained in liquid form. But the technology only matured gradually: whilst eight tons of charcoal were still needed to obtain two tons of pig iron in the 17th century, we now need only around half a ton of coke to produce 10,000 tons of pig iron a day.

Whilst searching for a robust material with which to make weapons, Henry Bessemer developed a new process in the middle of the 19th century which was to remain in use for a long time to come. The Bessemer process facilitates steel production by employing oxidisation. Up until then, workers had had to stir the molten steel in order to separate waste materials – a process which involved a great expenditure of energy. Now this could be taken over by a machine.

The Siemens-Martin process of 1864, which made it possible to melt scrap metal into steel, was a further milestone in steel production. And the steel industry kept on developing: ever better processes meant that much larger amounts of higher-quality steel could soon be manufactured with less manpower.

In 1850, each steelworker was producing eight tons of pig iron a year, twenty years later they were producing ten times as much.

In 1912, scientists in the Krupp cast steel works in Germany accidentally discovered how to manufacture rust-proof steel. So-called V2A or stainless steel is composed of iron, chromium and nickel and is used in medical technology for example.

Today, steel has become a high-tech material. For instance, so-called HDS (high strength and ductility) steel can make “intelligent crumple zones” possible. The idea is that the material, which deforms easily, becomes harder after a collision by means of structural transformations, thus providing better protection. Vehicle bodies made from this kind of “deforming steel” would not only increase security, they would also be especially light which would contribute to decreasing energy consumption.

(News collect by JUNSHENG MOULD )