The percentage of carbon determines the type of
steel and therefore its use.
When carbon is alloyed with iron we call the alloy carbon steel.
There are many different types of steel, it depends
on the elements you alloy iron with.
The elements that are added to iron to convert it
into an alloy are called additives.
Alloys contain more than one element and have the characteristic properties
of metals.
Advantage with alloying is that
the properties of the alloy surpass that of the metal (iron in this case).
Pure metals and alloys have different physical properties.