Nitrideering

Nitrideering is a surface hardening treatment in which nitrogen is diffused into the outer layer of a metal to form hard nitrides. The resulting nitride layer increases surface hardness, wear resistance, and fatigue strength while keeping the core properties of the substrate largely unchanged.

The term nitrideering is used in some contexts as a generic descriptor for diffusion nitride processes. Common methods include gas nitriding, plasma nitriding, salt bath nitrocarburizing, and other diffusion-based treatments. Gas nitriding and plasma nitriding typically operate at moderate temperatures for extended times, creating a nitrogen-rich case without melting the substrate. Salt bath nitrocarburizing is a lower-temperature alternative that can also introduce carbon for a dual nitride/carbon diffusion.

Substrates most often treated are low- to medium-carbon steels and certain alloy steels; stainless steels and some nickel-based alloys may also be nitrogenized under specialized conditions, though nitride chemistry and layer stability differ by alloy. The microstructure of the case consists of iron nitrides or nitride phases that form near the surface and grow inward by diffusion.

Benefits include higher surface hardness, improved wear resistance, and often enhanced fatigue performance. The nitride layer is typically adherent and diffusion-controlled, but excessive diffusion can induce brittleness or distortion if process parameters are not well controlled.

Limitations include potential brittleness at greater depths, possible distortion of complex parts, and the need for compatible post-treatment processes. Nitro-surface treatments are widely used for gears, bearings, cutting tools, and other components where surface performance is critical.