Steel

Steel, a mixture of several metals (this is called an alloy) but most of it is iron. Steel is harder and stronger than iron. Steels are often iron alloys with between 0.02% and 1.7% percent carbon by weight. Alloys with more carbon than this are known as cast iron. Steel is different from wrought iron, that has little or no carbon. There are some newer steels in which carbon is replaced with other alloying materials.

Cybermen are made of steel armour and living humans.