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Salt Bath Nitriding

Salt Bath Nitriding/Nitrocarburizing was originally created as an alternative to gas nitriding that would produce a more uniform case through surface contact between the substrate and liquid salt. When steel parts are placed into a preheated liquid salt, there is sufficient energy localized near the surface due to differences in chemical potential that then allows nitrogen and carbon species to diffuse from the salt into the steel substrate. The process is carried out at 750-1050°F, making it faster than gas nitriding. Lower temperature cycles produce an S-Phase/Expanded Austenite case in stainless steels. Post-oxidation after nitriding combined with polishing produces coatings with exceptional appearance (black color) and high corrosion resistance (greater than electrolytic chrome plating). To ensure part quality, our salt baths are continuously monitored, with chemistry adjustments made when necessary.

Nitrocarburized Layer

Nitrocarburized Layer

Salt Bath Nitriding/Nitrocarburizing is well known under various trade names, including ARCOR®, TENIFER®, TUFFTRIDE®, MELONITE®, and QPQ®.


  • Highly uniform case
  • Good white/compound layer formation
  • Layer microhardness: 800-1300 HV
  • Layer thickness: 0.0005”-0.008”
  • Low coefficient of friction: 0.1-0.2
  • Quick processing time
  • Corrosion resistance exceeds chrome plating
  • Fatigue life improvement


Salt Bath Nitriding is particularly common within the tool & die industry as well as the oil & gas industry. Common oil & gas components include impellers, diffusers, and pipe and drill pieces (i.e. drill heads). Frequently treated materials include mild steels, carbon steels, tool steels (A2, D2, M2, H13), and stainless steels (303, 304, 316). In addition, we offer development capabilities wherein specialty materials or components can be processed to ascertain the usefulness of salt bath nitriding to your specific application.