Carbon steels used in production consist not only of carbon and iron. For technological reasons, i.e. improved deoxidation or desulfurization, carbon steels also contain small traces of other elements, such as: silicon, manganese and aluminium. Steels also contain elements like sulphur, phosphorus, oxygen, hydrogen and nitrogen. Their total content is marginal, yet due to high costs removal of those elements is economically unjustified. Even small amounts of additional elements may affect the properties of the steel.

Carbon steels contain certain amounts of elements that are beneficial to their properties: Manganese – 0.8%, Tungsten – 0.2%, Molybdenum – 0.005%, Silicon – 0.4%, Cobalt – 0.2%, Vanadium – 0.05%, Nickel – 0.3%, Copper – 0.2%, Titanium – 0.005%, Chromium – 0.3% and Aluminium – 0.1%.

Undesirable elements that even in small amounts may be detrimental to steel properties are: sulphur, phosphorus, oxygen, hydrogen and nitrogen.