Carbon steel

An alloy of iron and carbon with no metal alloy elements deliberately added.

Also known as plain carbon steel. Carbon steels may contain small amounts of a wide range of residual elements from the manufacturing process. It is often loosely classified according to its carbon content:

Low carbon steel	Less than 0.2% carbon (Also known as mild steel)
Medium carbon steel	0.2-0.6% carbon
High carbon steel	more than 0.6% carbon

Carbon steel

An alloy of iron and carbon with no metal alloy elements deliberately added.

Low carbon steel	Less than 0.2% carbon (Also known as mild steel)
Medium carbon steel	0.2-0.6% carbon
High carbon steel	more than 0.6% carbon