Iron is a chemical element with atomic number 26.

It is, by and large, the most widely used metal worldwide. In fact, iron alone represents 95% of metal production worldwide. Thanks to its low cost and its resistance (in the form of steel), iron is an essential construction material. It is widely used in cars, boats, ships, and load-bearing elements in buildings.

The most widely used iron compounds include:

• pig iron, which contains between 4% and 5% carbon and varying amounts of impurities, such as sulphur, silicon and phosphorous. This material is mainly used at an intermediate stage in the production of cast-iron and steel;
• cast iron, which contains between 2% and 3.5% carbon and a lower percentage of the above-mentioned impurities. These do not impact negatively on the rheological properties of cast iron. Its melting point is between 1,150°C and 1,200°C, i.e. lower than that of iron and carbon as individual elements. Consequently, cast iron is the first to melt when iron and carbon are heated together. This material is extremely hard and brittle. It breaks easily, even when heated at white heat.
• carbon steel, which contains between 0.10% and 1.65% carbon. Depending on the quantity or percentage of carbon contained, carbon steel is divided into:

low-carbon steel (less than 0.15%);

medium-carbon steel (between 0.15% and 0.25%);

high-carbon steel (between 0.25% and 0.50%);

ultra-high carbon steel (over 0.50%);

• wrought iron, which contains less than 0.5% carbon (from a chemical point of view it is iron). This material is hard and malleable. Often the term “iron” is used both for low-carbon and medium-carbon steel;
• Since 1927, an especially pure type of iron, known as Armco iron, has been produced using a special procedure. It is used in cases where very high magnetic permeability and low magnetic hysteresis are required.
• special steels, which contain not only carbon, but also other metals, such as chrome, vanadium, molybdenum, nickel and manganese. Thanks to these metals, this alloy is physically or chemically resistant;
• iron oxide (III) (Fe2O3), in the form of magnetite and maghemite, is appreciated for its magnetic properties and is used in the production of storage media – for example, on magnetic tape polymers.