Nitridizing

Nitridizing is a surface hardening process used to improve the wear resistance and surface hardness of steel and other ferrous alloys. It involves diffusing nitrogen into the surface of the metal at elevated temperatures, typically between 450°C and 600°C. This diffusion results in the formation of hard nitride compounds within the metal's surface layer.

The nitriding process can be carried out using several methods. Gas nitriding is a common technique where the metal is heated in an ammonia atmosphere. The ammonia dissociates at the elevated temperature, releasing nitrogen that diffuses into the steel. Salt bath nitriding involves immersing the parts in a molten salt bath containing nitrogen-rich compounds. Plasma nitriding, also known as ion nitriding, uses a glow discharge in a nitrogen-containing plasma to introduce nitrogen.

The depth of the nitrided layer, known as the nitrided case, depends on factors such as temperature, time, and the composition of the base material. The nitrided case provides excellent wear resistance, increased fatigue strength, and improved corrosion resistance in some cases. It is a diffusion process, meaning it does not involve any volume change, thus minimizing distortion. Nitriding is often applied to components that require high surface durability, such as gears, crankshafts, camshafts, and cutting tools.