Ferritic Nitrocarburizing
Ferritic nitrocarburizing is a Case Hardening technique that uses heat, nitrogen and carbon to toughen up the exterior of a steel part, improving its durability, appearance and corrosion resistance.
Lower Temperatures for a Better Bottom Line.
Similar to carburizing and carbonitriding, ferritic nitrocarburizing is a case-hardening technique that uses heat, nitrogen and carbon to toughen up the surface of a steel part, improving its durability, appearance and corrosion resistance. Unlike many case hardening techniques, ferritic nitrocarburizing occurs at relatively low temperatures while the steel is in a ferritic phase, as opposed to an austenitic phase. The exact temperature depends on how the part will be used, but it’s typically between 950 degrees Fahrenheit and 1100 degrees Fahrenheit. These temperatures are low enough to prevent problems often associated with higher temperatures, such as distortion, while still allowing carbon and nitrogen to dissolve through the surface of the steel. Hardening techniques that use much more heat can cause distortion that has to be corrected, creating an extra step in the case-hardening process, costing valuable time and money. Virtually zero dimensional change makes FNC a common choice for surface hardening finish machined components across industries.
Industries that Use Ferritic Nitrocarburizing
Ferritic nitrocarburizing is an effective, economical case-hardening option for a broad range of parts, including:
- Drive train parts like crankshafts, camshafts, piston rods, and gears for cars, trucks and heavy equipment
- Firearms components like barrels and slides
- HPDC Dies (high pressure die casting) used to create castings for engine blocks, bell housings, transfer cases, and structural members.
Precision controls for specific parts
Computerized automation has made ferritic nitrocarburizing more popular in recent years, providing the exacting precision needed to form consistent diffusion zones and white layer. Our furnaces use computerized controls to apply precise amounts of nitrogen and carbon at an exact temperature to ensure consistency, part after part.
Frequently Asked Questions
What is ferritic nitrocarburizing?
Ferritic nitrocarburizing (FNC) is a case hardening process that diffuses nitrogen and carbon into the surface of steel while it remains in the ferritic phase—typically at lower temperatures between 950°F and 1100°F.Â
Unlike other hardening methods that require high heat and quenching, FNC achieves increased surface hardness, improved wear resistance, and enhanced corrosion protection with virtually no distortion. It forms a compound layer on the surface, ideal for components that require tight dimensional control and an attractive dark gray or black finish, such as pistons, gears, and firearm components.
What is the difference between FNC and gas nitriding?
Both FNC and gas nitriding are case hardening processes performed in gaseous atmospheres, but FNC adds both nitrogen and carbon to create a compound layer, while gas nitriding primarily adds nitrogen. FNC is primarily used to produce a very hard and wear resistant compound layer on the surface of parts which also imparts corrosion resistance. This compound layer is typically 0.0004-0.001″ in thickness. Gas nitriding is a case hardening process that allows parts to retain their shape through lower furnace temperatures. It’s primarily used to produce a diffusion zone in the base material of increased hardness due to the nitrogen diffusing inward. This diffusion zone is typically 0.010-0.030″ in thickness.
What is the recommended manufacturing sequence for FNC parts?
The optimal process flow is: rough machine your parts, perform any necessary heat treatment or hardening, complete finish machining to final dimensions, then apply FNC as the final step. Since FNC produces virtually zero dimensional change, it’s perfect for finished components where maintaining tight tolerances is critical.
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