What Does Nitriding Steel Mean?
Nitriding steel is steel treated by a highly specialized surface hardening process known as nitriding, which is a heat-treating process that diffuses nitrogen into the surface of a metal to create a case-hardened surface.
Case-hardening is a simple process of hardening the surface of a metal object. In this process, although the surface of the metal object becomes hard, the core of the metal object remains soft. This process is predominantly used for steel, but also used for titanium, aluminum and molybdenum.
Case-hardening is also known as surface hardening.
Corrosionpedia Explains Nitriding Steel
Nitriding steel is produced when steel is subjected to the nitriding process. In the nitriding process, nitrogen is diffused into the base steel to make the surface harder. This diffusion takes place at relatively low temperatures near 524°C (975°F). At this temperature, when nitrogen is diffused into the base steel, the hardening occurs without quenching.
The core properties of the steel object subjected to case hardening through the nitriding process are not affected until and unless the final tempering temperature for the product is kept higher than the nitriding process temperature. Nitride surfaces are highly wear resistant and provide anti-galling properties. Through the nitriding process, the fatigue life of the object is further improved. This process also helps to improve the object's corrosion resistance.
A wide variety of steel can be nitrided, however, the three most commonly used nitriding steels are:
- AISI 4140
- AISI 4340