Preheating and Pre-oxidizing

A part is normally preheated in air at 350 – 450 ºC for 60 – 120 minutes prior to nitrocarburizing. This is in order to:

  • Reduce the process time for nitrocarburizing.
  • Oxidize the surface to facilitate the formation of the compound layer. Little is gained from extended application periods since the increase in positive effects levels over time.
  • Evaporate and oxidize contaminations, which provides cleaner parts and improves nitriding properties, resulting in, among other things, a more even compound layer.
  • Improve the safety aspect of salt bath processes through evaporating any possible water residue

 

Ref. Steel and its Heat Treatment – A Handbook (8.12.6)