Intro
11%
FNC vs nitriding — stop confusing them
How carbon in the atmosphere changes the compound layer, why FNC owns stamping and powder-metal tooling, and how to tell the two processes apart on a quote and a microsection.
A stamping shop sends a set of D2 blanking dies out for "nitriding." The PO is one line. The certificate comes back with a 14 µm compound layer, surface HV 1050, ε-phase confirmed by XRD, a porous outer zone, and an atmosphere log that shows NH₃ with 2% CO₂. That is not nitriding. That is FNC. The dies will outlast a straight gas nitride on the same job. The next part the same shop sends, a P20 mold cavity going to a PVD coater, will get the same recipe and the PVD will delaminate. The atmosphere is the only thing that changed and the paperwork never mentioned it.