The steels parts will be placed in a furnace filled with nitrogen and then given the specific processing temperature, time, gas flow, and ammonia concentration depending on the hardening depths and requirements of the workpiece. This treatment will result in a relatively high-hardness surface due to the generation of nitrides and carbides in the microstructures. Moreover, the wear resistance and fatigue strength of the workpiece are also increased.
Nitriding-Sulfurizing Process
In addition to the advantages of the normal nitriding process, the parts will also have a layer of ferric sulfide at the surface in this case. It will act as a solid-lubricating film that can reduce the friction coefficient and the adhesive wear of the materials. For stainless steels, it can also be quite beneficial since it will reduce the protective layers of stainless steels to boost the nitriding process.
Plasma Nitriding
Nitrogen and hydrogen gas are mixed under low-pressure environment. Afterwards, a high-pressure direct current is applied, and the plasma that consists of N+, H+ and e- is formed. By utilizing the impact of this high-ionic energy, we can heat up the steels parts while nitriding it at the same time. The treated parts have high surface cleanness, and the nitridation layer formed is pretty dense and has minimized amount of porosities. This is why the materials in this case will have a much better fatigue strength when compared with that of other nitriding methods. For stainless steels, we can also apply low-temperature plasma nitriding, which will prevent the corrosion resistance from decreasing.
Benefits:
Unlike case hardening and quenching, since the nitriding temperature are relatively low, there are no such problems as distortion or cracking after this treatment. Moreover, depending on the alloying elements and contents of the steel parts, the hardness in this case might also be higher than that of case hardening method. The treated workpiece will not only have a higher wear resistance, fatigue strength, corrosion resistance, but also a relatively high resistance to softening at tempering temperatures.
Category
gas nitriding, plasma nitriding, nitrocarburizing, nitriding-sulfurizing process.