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What Is Gas Nitriding?

May 31st, 2023

Gas nitriding, or nitride hardening, is a heat treatment and surface hardening process that increases a metal’s surface strength, hardness, impact and wear resistance, and fatigue resistance.

It’s primarily used to extend the life of steel components and to comply with multiple industrial specifications and end-user requirements concerning mechanical properties and performance.

The Gas Nitriding Process

Gas nitriding is a thermochemical process because it relies on the application of heat to disperse nitrogen gas onto the metal’s surface. That gas is typically ammonia. Once exposed to the steel’s surface layer, the ammonia produces hydrogen, which, along with the nitrogen, adheres to the surface layer.

While the surface of the metal increases in hardness and strength with the additional nitride layer, the metal below the surface remains unchanged and retains its malleability. The temperature must be controlled throughout the process for nitride hardening to work.


There are several immediate and long-term benefits to using gas nitriding. Nitriding hardening increases the metal or alloy’s surface hardness and its resistance to heat, fatigue, abrasion, and corrosion. Nitride hardening also reduces the steel’s friction coefficient.


Nitriding hardening is primarily performed on low and medium-carbon steels, stainless steels, and steel alloys containing molybdenum and titanium. Gas nitriding may also be a post-treatment for hot-worked or cold-worked tool steels.


There are thousands of applications for nitride hardening. The process is recommended for any application that requires a metal with exceptional hardness, durability, corrosion, wear, and fatigue resistance. 

Common components that often go through the gas nitriding process include camshafts, valves, gears, forging dies, die-cast tooling, shaft pins, nuts, and bolts.

Learn More About Gas Nitriding Today

SST is a highly reputable heat treatment company that has provided case hardening, precipitation hardening, and other services since 1956.

Contact us today if you have questions about gas nitriding or want to learn more about our capabilities.

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Wayne Thomas
Wayne Thomas
17:55 19 Jun 17
Before I retired, I was the coordinator for our plant's aerospace, and precision heat treated product, and SST. I couldn't have asked for better quality, and service. I recommend them 100 percent.
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