Answer:
Steel is an alloy of iron and carbon containing 0.1to1.5% carbon. Thus, the constituents of steel are iron and carbon. Pure iron is not very hard and strong.
It is brittle and, therefore z it cannot be used for structural proposes. Hence, most of the molten pig iron obtained from blast furnace is converted into steel.
Steel is very hard, tough and strong. It is used for making rails, screws, girders, bridges, railway lines, etc. Steel also can be used for the construction of buildings, vehicles, ships, etc