Carbon steel, also called plain-carbon steel, is a metal alloy, a combination of two elements, iron andcarbon, where other elements are present in quantities too small to affect the properties. The only other alloying elements allowed in plain-carbon steel are: manganese (1.65% max), silicon (0.60% max), and copper(0.60% max). Steel with a low carbon content has the same properties as iron, soft but easily formed. As carbon content rises the metal becomes harder and stronger but less ductile and more difficult to weld. Higher carbon content lowers steel's melting point and its temperature resistance in general.
Typical compositions of carbon are:
Mild (low carbon) steel: approximately 0.05% to 0.25% carbon content with up to 0.4% manganese content[1](e.g. AISI 1018 steel). Less strong but cheap and easy to shape; surface hardness can be increased throughcarburizing.[2]
Very high carbon steel: approximately 0.96% to 2.1% carbon content, specially processed to produce specific atomic and molecular microstructures
Steel can be heat-treated which allows parts to be fabricated in an easily-formable soft state. If enough carbon is present, the alloy can be hardened to increase strength, wear, and impact resistance. Steels are often wrought bymethods, which is the shaping of metal through deformation at a low equilibrium or metastable temperature.
