Carbon steels

Iron alloy with carbon

Carbon steel is a metal alloy, which is formed by the combination of iron and carbon. Usually steel is considered carbonaceous, when the total content of other alloying elements does not exceed a certain percentage. Usually, eg, maximum manganese content does not exceed 1,6 %, silicon - 0,6 % and copper - 0,4 %. If the steel contains a higher amount of other elements, such as nickel, chrome or vanadium, then it is already considered alloy steel.

Steelmakers add carbon to iron, to make the alloy structure harder, and the resulting steel is more durable. Carbon is the cheapest alloying element in steel and, changing its content, the properties of the steel can be largely controlled. Usually carbon steels are classified as low carbon, medium carbon, high carbon and high strength carbon (ledeburite) become.

Low carbon steel

Very low carbon steels - from 0,05 to 0,3 % – called low carbon steels. They are like iron, as it is very soft and plastic, which complicates their machining by cutting. They are used in the form of sheets, tapes, wire. Low carbon steels are cheaper than other steels, but their properties cannot be changed by heat treatment.

Medium carbon steel

Increasing carbon content makes carbon steels harder and stronger, but this reduces their weldability and ductility, which makes steel more brittle. Steelmakers also add small amounts of other alloying elements to carbon to improve the properties of the steel., eg, viscous properties.

Medium carbon steels have a carbon content of 0,3 to 0,6 %. They are easier to machine mechanically. Some steels additionally add silicon and manganese to improve machinability.. These steels are still relatively cheap and are used, including, for such critical products, like pipes and rails.

High carbon steel

High carbon steels are very difficult to weld, since they contain from 0,6 to 1,0 % carbon. They are also high in manganese, which is added to increase the hardenability of steel. These steels are easily hardened by heat treatment.. They have high strength and are used for the manufacture of tools, cutting blades, springs and high-strength wire.

Ledeburite steel

Ledeburite steels contain carbon from 1,25 to 2,0 %. They are not cold worked, as they are very fragile. Ledeburite steels are used for the manufacture of parts, requiring very high hardness, such as blades, cutting tools and large products. Ledeburite steels are very sensitive to heat treatment, have good machinability and very high wear resistance.

GUEST 380-2005