Ferritic Nitro-carburizing (FNC) is a form of Nitriding with added carbon in the gas mixture. Nitrogen and Carbon are diffused into the part surface to create a hard case that is highly wear resistant and corrosion resistant. This case hardening technique is widely used on low carbon steels, cast iron, annealed alloy steels with low mechanical strength needing wear and corrosion resistance property improvements. In most cases, the through hardened parts cannot achieve a mechanical strength to provide wear resistance equivalent to a Ferritic-Nitrocarburized part. As the process is carried out below the transformation temperature, the parts see little to no distortion.
This process should not be confused with Carbo-Nitriding. Although using similar gas mixtures, Carbo-nitriding is carried out at above transformation temperatures and causes distortion. The FNC is often combined with a subsequent Black Oxide to provide extended corrosion resistant capabilities.
At ANS, we have the technology to control the Gas Mixture, and Gas volume (Nitrogen and Carbon potential) to control the amount of Compound/White Layer and the composition of the white layer to meet various application needs.
FNC is often specified as the equivalent alternative to Salt Bath Nitriding/Salt Bath Nitrocarburizing in industrial applications on the merit of being an environmentally friendly process. The Salt Bath Nitride process is dependent on cyanides and cyanide variants, producing hazardous waste.
In FNC and Gas Nitriding, the source of Nitrogen comes from Ammonia. Also, for environmental reasons, FNC is rapidly replacing Hard Chrome Plating. Chrome Plating, although having great wear resistant properties, are prone to corrosion. Much like many other plating, the chrome plating has a crystalline structure. The crystals do not grow on surface contamination or surface imperfections, causing microscopic gaps in the plating called micro-cracks. The corrosion propagates almost instantly in these cracks. FNC is a diffusion process which does not leave any surface untreated, and is a better alternative to Chrome Plating for corrosion resistance, as well as an environmentally responsible alternative.
Materials Suited for FNC:
- Low/Medium Carbon Steels that are hot rolled or cold rolled: 1010, 1018, 1045, 12L14, 1215
- Alloy Steels that are hot rolled or cold rolled: 4140, 4340
- Low Alloy Steels: 5120, 9310, 8620
- Cast Iron and Cast Steels
Advanced Nitriding Solutions is certified to provide AMS 2757 B.