Nitrided Steel
Nitriding is a thermochemical process used to increase the surface hardness and wear resistance of metals. The most common metal treated in this way is steel, although it works with other metals as well. The primary benefit of nitriding is that it can be used to improve the mechanical properties of steel without compromising its strength or ductility.
Nitriding is a heat treating process that diffuses nitrogen (usually from ammonia) into the outer layers of steel. This process creates a hard, wear-resistant surface layer known as the nitrogen-enriched layer, or NEL. The NEL strengthens the steel by increasing its surface hardness and wear resistance without compromising its ductility. Additionally, nitriding can improve corrosion resistance and fatigue strength by increasing surface hardness, reducing surface friction and decreasing oxidation.
The nitriding process usually takes place in a carefully controlled atmosphere at temperatures just below the steels recrystallization temperature. This ensures that the nitrogen is properly diffused into the steels surface while still allowing the metal to retain its shape and size.
The depth of the nitrogen-enriched layer depends on a variety of factors including the starting material, its composition and the temperature and duration of the nitriding process. The depth of the enriched layer can range from a few microns to several millimeters depending on the application and the nitriding parameters.
The Nitrided Steel Process
The nitriding process involves first pre-treating the steel to achieve a smooth, clean surface. Scales must be removed before the nitriding process begins. The pre-gender condition can involve pickling, polishing, acid etching, shot blasting or some other method based on the steel type and the desired results.
Once the steel has been pre-treated, it is then placed in a specifically designed furnace. The furnace temperature and atmosphere are carefully controlled using temperature gauges and monitors. Once the desired temperature has been reached, an ammonia-based gas mixture is injected into the furnace and the nitriding process begins.
The nitrogen diffuses quickly into the steels outer surface creating an iron-nitride compound known as gamma-fer. Gamma-fer is a tough, wear-resistant layer that is significantly harder than the steel itself. This layer of gamma ferrite is what gives nitrided steel its characteristic hardness and wear resistance.
Nitrided steel can be used in a variety of automotive, aerospace and industrial applications. Its highly wear-resistant properties make it ideal for parts that need to be able to withstand extreme wear and tear. It can also be used to improve the fatigue strength, stability and wear resistance of engine, transmission and other automotive parts. In other industries, nitrided steel can be used for applications that require a high level of wear resistance such as cutting tools, shafts and gears.
Overall, nitrided steel is an effective way to improve the performance of steel components without compromising strength or ductility. By controlling the nitriding process, the desired properties can be achieved in the steel part while ensuring that the individual parts retain their shape, size and integrity. With its unique combination of hardness and durability, nitrided steel is a valuable choice for many engineering and industrial applications.
