Nitriding is a heat treatment process used to harden the surface of metals, particularly steel. It involves introducing nitrogen into the surface layer of the metal, which forms hard nitrides. This process enhances wear resistance, fatigue strength, and corrosion resistance, making it ideal for components like gears and crankshafts. The nitriding process typically occurs at lower temperatures compared to other heat treatments, which helps maintain the core properties of the metal. It can be performed using various methods, including gas nitriding, salt bath nitriding, and plasma nitriding, each offering different advantages for specific applications.