Like oil, steel is subject to frequent price increases, although – unlike that – it can be recycled. The Injection Moulding industry is thus studying the possibility of replacing it with other materials. In particular, an alternative could be provided by particular polymers, that is by plastic materials that are able to simulate the characteristics of metal alloys. Polymer panels used to build appliances are already on the market today.
Bessemer also invented the mobile converter, an oven mounted on pins which, once the alloy was melted, rotated emptying its contents. Subsequent improvements were made with systems to recover heat and eliminate phosphorus, but by now the basic principles of fusion had been substantially discovered. Another widespread production method in which molten steel is obtained by refining iron and steel scrap as part of Injection Moulding.
Furthermore, starting from 1850, electric ovens also spread, in which heat is no longer produced by means of fuel but by means of an electric arc. At the end of the 19th century we can certainly say that steel became one of the cornerstones of the western world. From 1879 to 1900 world production increased more than fifty times, growing from half a million tons to 28 million. Thanks to steel, the Old and New Continents were covered by a dense railway network structured on steel rails, which lasted longer than those made of iron material used for Injection Moulding up to that time.
Steel began to be used for the construction of locomotive and ship boilers and for the construction of ever larger and more robust ships: the transatlantic liners. In 1874, in the United States, the Eads Bridge was built on the Mississippi, in Saint-Louis, the first bridge to have a steel and iron bearing structure.
Steel was therefore increasingly used for the construction of civil structures, such as, for example, skyscrapers: the Empire State Building, inaugurated in 1931 and 381 m high, was built using 57,000 tons.
Some of these are covered with a thin metallic layer to provide an almost perfect illusion. Also in the building sector some polymers are used to strengthen the cement. Thus in England, in Oxfordshire, a reinforced concrete bridge was built whose structure is reinforced by polymers. In October 2002 the bridge was inaugurated with the passage of a Sherman tank, a colossus that has a mass of about 40 tons thanks to Injection Moulding.
