A loss of carbon from the surface layers of steel caused by the steel having been held at high temperatures in an oxidising atmosphere.

Reduction of the carbon content in the steel. It can be accomplished when the steel is molten when the cast iron is being transformed into steel, at the solidified superficial area of the steel in the course of heat treatment or in special plant designed to lower the content drastically.

The loss of carbon from the surface of steel as a result of heating in a carbon weak atmosphere. During the rolling of steel hot surfaces are exposed to the decarburising effects of oxygen in the atmosphere and as a result the surface is depleted of carbon. In steels where the components are to be subsequently heat treated it is necessary to remove the decarburised surface by machining.