Carbon Steels
Carbon steel is steel in which the main interstitial alloying constituent is carbon in the range of 0.12–2.0%. The American Iron and Steel Institute(AISI) defines carbon steel as the following: "Steel is considered to be carbon steel when no minimum content is specified or required for chromium,cobalt, molybdenum, nickel, niobium, titanium, tungsten, vanadium or zirconium, or any other element to be added to obtain a desired alloying effect; when the specified minimum for copper does not exceed 0.40 percent; or when the maximum content specified for any of the following elements does not exceed the percentages noted: manganese 1.65, silicon 0.60, copper 0.60."[1]
The term "carbon steel" may also be used in reference to steel which is not stainless steel; in this use carbon steel may include alloy steels.
As the carbon percentage content rises, steel has the ability to become harder and stronger through heat treating, however it becomes less ductile. Regardless of the heat treatment, a higher carbon content reduces weldability. In carbon steels, the higher carbon content lowers the melting point.[2]
Types
See also: SAE steel grades
Carbon steel is broken down into four classes based on carbon content:
Mild and low-carbon steel[edit]
Mild steel, also called plain-carbon steel, is the most common form of steel because its price is relatively low while it provides material properties that are acceptable for many applications, more so than iron. Low-carbon steel contains approximately 0.05–0.3% carbon[1] and mild steel contains 0.3–0.6%[1] carbon; making it malleable and ductile. Mild steel has a relatively low tensile strength, but it is cheap and malleable; surface hardness can be increased through carburizing.[3]
It is often used when large quantities of steel are needed, for example as structural steel. The density of mild steel is approximately 7.85 g/cm3(7850 kg/m3 or 0.284 lb/in3)[4] and the Young's modulus is 210 GPa (30,000,000 psi).[5]
Low-carbon
The term "carbon steel" may also be used in reference to steel which is not stainless steel; in this use carbon steel may include alloy steels.
As the carbon percentage content rises, steel has the ability to become harder and stronger through heat treating, however it becomes less ductile. Regardless of the heat treatment, a higher carbon content reduces weldability. In carbon steels, the higher carbon content lowers the melting point.[2]
Types
See also: SAE steel grades
Carbon steel is broken down into four classes based on carbon content:
Mild and low-carbon steel[edit]
Mild steel, also called plain-carbon steel, is the most common form of steel because its price is relatively low while it provides material properties that are acceptable for many applications, more so than iron. Low-carbon steel contains approximately 0.05–0.3% carbon[1] and mild steel contains 0.3–0.6%[1] carbon; making it malleable and ductile. Mild steel has a relatively low tensile strength, but it is cheap and malleable; surface hardness can be increased through carburizing.[3]
It is often used when large quantities of steel are needed, for example as structural steel. The density of mild steel is approximately 7.85 g/cm3(7850 kg/m3 or 0.284 lb/in3)[4] and the Young's modulus is 210 GPa (30,000,000 psi).[5]
Low-carbon