Steel Iron

Pure iron is soft and easily shaped. This is because its atoms are arranged in a regular way that lets layers of atoms slide over each other. Pure iron is too soft for many uses.

Layers of atoms slide over each
other when metals are bent or stretched

Iron from the blast furnace is an alloy of about 96 per cent iron with carbon and some other impurities. It is hard, but too brittle for most uses. So, most iron from the blast furnace is converted into steel by removing some of the carbon.

Steel

Carbon is removed by blowing oxygen into the molten metal. It reacts with the carbon producing carbon monoxide and carbon dioxide. These escape from the molten metal. Enough oxygen is used to achieve steel with the desired carbon content. Other metals are often added, such as vanadium and chromium.

There are many different types of steel, depending on the other elements mixed with the iron. The table summarises the properties of some different steels.

A summary of the properties of some different steels

type of steel	iron alloyed with	properties	typical use
low carbon steel	about 0.25 per cent carbon	easily shaped	car body panels
high carbon steel	up to 2.5 per cent carbon	hard	cutting tools
stainless steel	chromium and nickel	resistant to corrosion	cutlery and sinks