Gas Nitriding

Low Temperatures, High Resistance.

Gas nitriding is a heat treatment process that allows parts to retain their shape through lower furnace temperatures. Often, the stress of high temperatures and rapid cooling during hardening will cause distortion in parts that will require additional, sometimes costly, machining.

During this process, ammonia (NH3) is injected into the furnace, breaking apart upon contact with the part. The nitrogen —which is soluble in iron at nitriding temperatures— then diffuses into the piece. The process is controlled by monitoring how much of the ammonia has broken apart during the process.

The hardness a part achieves in gas nitriding is dictated by the composition and microstructure of the alloy. More complex alloys respond better and are usually hardened and finished before nitriding. The hardness is added at the part’s surface, but its core remains comparatively soft and ductile.

Because gas nitriding achieves the desired qualities without a phase change, there’s no need for quenching. Parts also do not need to be tempered following gas nitriding because the specified hardness, strength and wear resistance levels can be achieved based on adjustments made to the furnace temperature, gas content, gas flow and process time.

Benefits and Applications

Workpieces that respond best to gas nitriding include finished machined parts like tool steels or forging dies. Gas nitriding also improves automotive components like crankshafts and valve parts as well as firearm components like slides and barrels.

The benefits of gas nitriding include:

Cutting Edge Technology for Precision Parts.

Gas nitriding is a good case hardening option for parts that must retain their precise shapes to perform as designed. Heat treatment methods carried out at higher temperatures, such as neutral hardening with an oil or water quench, increase the risk that a part will distort, which can cause the additional steps of re-machining parts, adding to costs and timelines. Paulo’s state-of-the-art computer-controlled systems deliver precise temperatures and gas flow to ensure consistency across all batches and finished parts that always meet stated specifications. We also offer precision vacuum nitriding services in our Nashville division for specialized applications.