It consists of a thermo-chemical process to obtain the superficial hardening of a part of the piece. It is followed with pre and post oxidation of the surface of the treated piece. This treatment applies a simultaneous diffusion of nitrogen and carbon in order to obtain consecutive nitride and carbonitride layers on the surface of the piece. These layers get more superficial hardness.

The ablative and antioxidant steel properties are improved through the pre and post-oxidation of the surface.

This heat treatment is applied to moulds, special gears, mould making, stamps and tools.

.