Ferritic nitrocarburizing, done in gas, salt or plasma at about 550 to 590 °C while the steel stays ferritic, so there is no phase change and very little distortion. It builds a compound layer of iron nitrides and carbonitrides, typically 10 to 25 micrometers thick, over a nitrogen diffusion zone. It improves wear, scuffing and fatigue resistance, and a follow-up oxidizing step gives a black finish with good corrosion resistance.
Brake rotors go through FNC with a post-oxidize, keeps them from rusting on the dealer lot.
Also heard as
- ferritic nitrocarburizing
- nitrocarburizing
- nitrocarb
Related terms
Nitriding
Diffusing nitrogen into steel below its critical temperature to form a hard case with no quench.
White layer
The thin, hard compound layer of iron nitrides that forms on the surface during nitriding.
Carbonitriding
Adding both carbon and nitrogen to a steel surface at a lower heat than carburizing, then quenching.
Salt bath
A pot of molten salt used to heat, quench or case harden parts by quick, even immersion.