Nitriding

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.

Nitral® Nitriding

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+N_2O+ 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.