What is Carbon steel?
'''Carbon steel''' or '''plain-carbon steel''', is a metal [[alloy]]. It is a combination of two elements, [[iron]] and [[carbon]]. Other elements are present in quantities too small to affect its properties. The only other 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 [[concentration|content]] has the same properties as iron, soft but easily formed. With more carbon the metal gains [[hardness]] and strength but becomes less [[ductile]] and more difficult to [[welding|weld]]. Higher carbon content lowers steel's [[melting point]] and its temperature resistance in general. == Types of carbon steel == Typical compositions of carbon are: * '''Mild (low carbon) steel''': approximately 0.3% carbon content with up to 0.4% manganese content<ref name=kts>[http://www.key-to-steel.com/Articles/Art62.htm Classification of Carbon and Low-Alloy Steels]</ref> (e.g. AISI 1018 steel). Less strong but cheap and easy to shape; surface hardness can be increased through [[Carburization|carburizing]].<ref>[http://efunda.com/materials/alloys/alloy_home/../carbon_steels/low_carbon.cfm Engineering fundamentals page on low-carbon steel]</ref> * '''Medium carbon steel''': approximately 0.30% to 0.45% carbon content with 0.60 to 1.65% manganese content<ref name=kts/>(e.g. AISI 1040 steel). Balances ductility and strength and has good wear resistance; used for large parts, forging and car parts.<ref>[http://efunda.com/materials/alloys/alloy_home/../carbon_steels/medium_carbon.cfm Engineering fundamentals page on medium-carbon steel]</ref> * '''High carbon steel''': approximately 0.45% to 0.75% carbon content with 0.30 to 0.90% manganese content.<ref name=kts/> Very strong, used for springs and high-strength wires.<ref>[http://efunda.com/materials/alloys/alloy_home/../carbon_steels/high_carbon.cfm Engineering fundamentals page on high-carbon steel]</ref> * '''Very high carbon steel''': upto 1.5% carbon content, specially processed to