Decarburization

The loss of carbon from the surface of the ferrous alloy (i.e. steel) as a result of heating in a medium that reacts with the carbon at the surface. It typically occurs when a steel is heated above the lower limit of its recrystallization temperature, usually around 700 degrees Celsius. When steel is elevated to this temperature and exposed to gases such as hydrogen and oxygen, the steel’s carbon bonds with those gases and leaves the steel with a reduced amount of carbon.

Since the gases are only in contact with the surface of a steel, decarburization generally occurs most heavily on the outermost layers of a steel. The carbon reduction results in a loss of tensile strength, fatigue strength, and hardness.

The amount of decarburization that occurs depends on the types of processing and fabrication used.

< Glossary