Also known as "mild" or "plain" steel, carbon steel contains only carbon, with residual impurities. Magnetic, malleable metal is ideal for cold-forming, bending, and welding, but as carbon content rises, the metal becomes harder, stronger, less ductile, and more difficult to weld. Can also be cast or wrought. Heat treating allows parts to be fabricated in a softer state, then hardened for increased strength. Carbon content still affects hardness, with greater carbon content ultimately producing a harder finished product.

CARBON STEEL COMPARISON CHART
Material	Tensile Strenth (psi)*	Yield Strength (psi)*	Hardness (BHN)*	Toughness	Wear Resistance	Formability	Machinability†	Weldability Excellent
Low Carbon Grade
Low Carbon	58,000-80,000	36,000	137	Fair	Fair	Excellent	Good	Excellent
1018	65,000-85,000	55,000-75,000	167	Fair	Fair	Good	Good	Excellent
Medium Carbon Grade
1144	100,000	95,500	223	Good	Poor	Fair	Good	Poor
Screw Machine Grade
12L14	78,000-85,000	60,000-75,000	187	Poor	Poor	Poor	Excellent	Not Recommended
1215	78,000-95,000	60,000-80,000	187	Poor	Fair	Not Recommended	Excellent	Not Recommended
(*) Typical levels @ 1" diameter. (†) Compared to AISI 1212, which has 100% machinability.