The automotive industry relies on steel to manufacture safe, durable vehicles that last for years. The steel used in automobile components goes through a range of heat treatment processes to increase its strength. Nitriding is one of the most common heat treatments used in the automotive industry.

Heat treatment and surface modifications such as nitriding are used to achieve the desired properties of the components used by manufacturers in the automotive industry. The nitriding process dissolves nitrogen into the surface of steel to harden a part without bringing it above critical temperature, thereby all but eliminating the risk of distortion, which makes it a popular choice for improving an ever-widening variety of automotive parts.

What is Nitriding?

In use as a case-hardening technique since the early 20^th century, nitriding is an effective lower-temperature heat treatment for steel work pieces used in the automotive industry. Nitriding is a surface-hardening process that introduces nitrogen into the surface of steel parts, which increases wear resistance, surface hardness and fatigue life. The process is performed in a nitriding furnace that uses dissociated ammonia, which is an atmosphere of hydrogen and nitrogen.

Nitriding creates a very hard case on a component at relatively low temperatures. Alloy steel changes when it reaches high temperatures, known as transformation temperature. Nitriding is performed at temperatures lower than the transformation temperature of alloy steels, so the process causes little or no distortion to the treated piece. Furthermore, quenching, a rapid cooling process, is not necessary with nitriding.

Nitriding furnaces expose parts to active nitrogen at carefully controlled temperatures, usually in the range of 925°F to 985°F. Because this temperature is below the final tempering temperature of steel, the process does not affect the mechanical properties of the base metal. The result is a very high strength product with excellent wear resistance and little or no dimensional change. The process of nitriding improves fatigue strength mainly through the development of surface compressive stresses, which prevents small cracks from growing to the point of fracture.

Automotive manufacturers prefer nitriding for components subjected to heavy loading because nitriding imparts a high surface hardness that promotes exceptional resistance to wear, scuffing, and seizure. The surface hardness also does a superior job of resisting galling by reducing adhesion between sliding surfaces. Nitriding furnaces effectively strengthen many of the nitride-forming elements commonly used in the automotive industry, including chromium, molybdenum, vanadium, and aluminum. The process is also applicable to tool steels used in the automotive industry, including hot-work, cold-work and mold steels

Check back next month to learn more about the use of nitriding in the automotive industry. Lindberg/MPH is a leading manufacturer of industrial heat treating furnaces, with 75,000 industrial furnace installations worldwide, including numerous installations serving the automotive industry. If you enjoyed this information be sure to follow Lindberg/MPH on both Facebook and LinkedIn!