Mild Low Carbon Steel:

Approximately 0.05% to 0.25% carbon content with up to 0.4% manganese content. Less strong but     cheap and easy to shape; surface hardness can be increased through carburizing.

Medium Carbon Steel:

Approximately 0.29% to 0.54% carbon content with 0.60 to 1.65% manganese content. Balances ductility and strength and has good wear resistance; used for large parts, forging, and car parts.

High Carbon Steel:

Approximately 0.55% to 0.95% carbon content with 0.30 to 0.90% manganese content. Very strong,  used for springs and high-strength wires.

Very High Carbon Steel:

Approximately 0.96% to 2.1% carbon content, specially processed to produce specific atomic and     molecular micro-structures.

Steel can be heat-treated which allows parts to be fabricated in an easily form-able soft state. If enough carbon is present, the alloy can be hardened to increase strength, wear, and impact resistance. Steels are often wrought by cold-working methods, which is the shaping of metal through deformation at a low equilibrium or meta-stable temperature.