Metals can be divided into 2 main categories: ferrous metals and non-ferrous metals.

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Ferrous Metals

As the name suggests, ferrous metals contain iron. Iron is a chemical element that is extremely difficult to shape without the addition of other elements, of which carbon is the most prevalent. Consequently, ferrous metals are grouped into 4 main classes according to carbon content: irons, steels, cast irons, and iron carbide.

 

1. Iron has almost no carbon, a maximum of 0.02% (wt). Iron is found mainly in decorative pieces of wrought iron.

 

2. Steels contain between 0.02% and 2.1% (wt) of carbon and are divided into 3 main categories depending on the content of elements other than carbon:

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• Unalloyed steel (called carbon steel or, simply, steel). These steels have only traces of other alloying elements and are used in a large number of applications such as beams, sheets, railway rails, and some gears.

• Low alloy steels – These steels, also called alloy steels, are used for the manufacture of boats, heavy equipment, chains, and gears, among other uses.

• High alloy steels – These steels, depending on their composition, are known by different names: stainless steel, tool steel, spring steel, and others.

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1. Cast iron contains between 2.1% and 6.7% carbon. Cast iron is found in saucepans, automobile engine blocks, and brake discs. Cast irons have a high hardness, good ductility, tensile strength and fatigue strength, and absorb energy.

 

2. Iron carbides have more than 6.7% carbon, which makes them very hard as well as brittle. They have very good resistance to abrasion and erosion, and to heat. Iron carbide is considered a ceramic in its pure state and is used to produce steel.