Ferritic Oxidized Nitrocarburizing

Standard – UNI 10931
Typical materials – 42CrMo4, 39NiCrMo3, 41CrAlMo7, C40, etc.
Achievable metallurgical characteristics – Surface hardness varies depending on the material and pre-treatment hardness level. Values range from 450-1200HV.
Effective nitriding depth: 0.10-0.60mm

The ferritic oxidized nitrocarburizing process is typically applied to finished parts at the end of all mechanical operations. In some cases, depending on the application and the required level of finishing, subsequent lapping may be necessary.

Nitrocarburizing enhances the surface hardness of components without affecting the core mechanical properties. Additionally, this process ensures high resistance to wear and corrosion. It is widely used in the automotive sector, particularly in transmission shafts, where it significantly improves fatigue resistance.

The process involves heating the components to temperatures lower than those used for austenitization, typically between 540-580°C, in a controlled atmosphere that allows the surface diffusion of nitrogen and carbon into the components. The dwell time can be adjusted to control the desired depth as per design specifications. As this is a slow diffusion process, the depths achieved are much shallower than those in thermochemical processes like carburizing.

Afterward, the components undergo a controlled oxidation process in the furnace, which gives the parts a black color and a high resistance to sliding wear.

The low treatment temperatures help significantly reduce deformation, especially if the process is preceded by preliminary hardening and/or stabilization treatments at temperatures of at least 600°C.