Nitridöintiä

Nitridöintiä is a Finnish term referring to nitriding, a thermochemical surface hardening process for ferrous materials. It involves diffusing nitrogen into the surface of the steel at elevated temperatures, typically between 500 and 575 degrees Celsius, without melting the base material. This process creates a very hard, wear-resistant surface layer composed of iron nitrides.

The diffusion of nitrogen is usually achieved by exposing the steel part to a nitrogen-rich atmosphere, such as ammonia gas. The ammonia dissociates at the elevated temperature, releasing atomic nitrogen which then diffuses into the steel's surface. This results in the formation of a compound layer and a diffusion zone beneath it.

Nitriding is particularly effective for steels containing nitride-forming elements like chromium, molybdenum, vanadium, and aluminum, as these elements enhance the hardness and stability of the nitride layer. The process can be performed in various ways, including gas nitriding, salt bath nitriding, and plasma nitriding, each offering different advantages and applications.

The primary benefits of nitriding include significantly increased surface hardness, improved wear resistance, enhanced fatigue strength, and good corrosion resistance. Unlike carburizing, nitriding is a low-distortion process, meaning parts retain their dimensional accuracy, making it suitable for precision components like gears, crankshafts, and tools. The nitrided layer is also relatively thin, typically ranging from 0.01 to 0.75 millimeters, but possesses exceptional hardness.