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HEAT TREATMENT c.c.
  Specialists in Heat Treatment

  NITREG® - POTENTIAL CONTROLLED NITRIDING 
  Technical Information

ONC®: In-process Post-Nitriding/Nitrocarburizing Oxidation

When resistance to atmospheric corrosion and an attractive black finish are the predominant requirements, ONC® is the appropriate process.

Its objective is to transform the very top portion of the WL obtained with either Nitreg® or Nitreg®-C technologies into a complex spinel type structure consisting mostly of Fe3O4 type of iron oxide.

Such a post-nitriding oxidation treatment has a net effect of enhancing the corrosion resistance of an already nitrided component. This integrated process (i.e. Nitreg + ONC® or Nitreg®C + ONC®) simultaneously enhances corrosion and wear resistance of steel, while giving the surface an attractive dark or black appearance, expressly desired by many customers.

ONC®, applied in combination with the Nitreg® potential-controlled nitriding process or the Nitreg®-C potential-controlled nitrocarburizing process, is a clean technology that in many instances can replace chrome plating and salt bath nitriding with their inherent problems of pollution and cost.

Depending on the type of steel, parts treated in the Nitreg®-ONC process can easily pass well over 200 hours of salt-spray test per ASTM B117 before the first corrosion spot appears. Fig. 2 shows a comparison of metallurgical and corrosion test results obtained on three materials treated by the Nitreg®-ONC process.

Benefits:

  • Improved corrosion resistance

  • Attractive black surface finish

  • Inherent wear resistance