Usually the steel is a mixture of 2 elements: Iron and some quantity of carbon. The quantity of carbon shall be between 0.03% - 2.14%. The steel is used in the industry of construction, buildings. Also is used in the industry of ships, to form machines, to form small or big tools, for the manufacturing of weapons, in the industry of trucks, cars, bicycles etc. These two materials are also used to form roads ,railways too. We shall keep in mind the difference between Iron and Steel. They look similar but are not same. They look similar because both are very hard materials. These two materials are also used to form roads, railways too. In Merv, during the ninth & tenth century the steel was already produced with a very primitives techniques. They were cooling & heating the coal and iron. In China , during the 11th century the productivity of the steel was going very good, they had their own 2 techniques. In Armenia , nearly 1400 BC C , there was existing the production of Iron, They had nine or eleven methods for the Iron production. Between 1100 and 13000 BC C these methods were being spreading in the different countries. In the present time in the nature there is a very big quantity of Iron and coal, which helps a lot for the production of the Steel. When we apply a special heat treatment we get the Steel with excellent properties of hardness and mechanical strength. The thermal treatments helps to change the microstructure of the material and with this the macroscopic properties are also altered.
There are a variety of steel as Alloy steels, carbon steels and standards.