Nitriding is another thermo-chemical surface hardening treatment that increases resistance to wear, friction, corrosion and fatigue while improving sliding friction. This process creates a hard surface layer through nitrogen diffusion without subsequent quenching.
Nitriding is different from other surface treatments such as carburizing, carbonitriding, induction treatment and flame hardening, in that it creates only a thin, superficial, hard layer (0.020″ / 0.5 mm max.) without subsequent quenching.
Thermetco uses the Nitral® process. This is a process similar to gas treatments, but uses reduced pressure in a vacuum furnace. To do this, we use an Alnat N type atmosphere: NH3+N2O+ N2. Working pressures are between 200 and 400 mbar. The nitriding power of the atmosphere is regulated so as to control the nitrogen enrichment of the matrix and obtain a high-quality nitrided layer.
The low pressure Nitral® process combines all the advantages of other nitriding processes (ionic, gaseous or salt bath) and produces clean parts.
Advantages of the Nitral® process
- Treatment of bored and broached parts or with deep, narrow and blind holes
- Produces very clean parts
- Precise selection of the surface layer (depending on the grade to be hardened and the applications)
- Minimum to no deformation (subject to previous stress relief)
Most commonly used grades of steel:
- Nitraloy, a steel specially designed for nitriding
- Low alloy steels: 4140HT, 4340HT, P20
- Tool steels: D2, H13, S7
Nitriding is often the perfect complement to vacuum quenching of tool steels.