QPQ Liquid nitriding (also known as salt bath nitriding) is a process for producing a thin, high-hardness case that is wear and corrosion resistant, with little or no distortion of the part during processing.
The resulting lustrous black finish is an effective alternative for both chrome and nickel plating.
Liquid nitriding is suitable for a wide variety of carbon steels, low alloy steels, tool steels, cast irons, and stainless steels. Because liquid nitriding is a relatively low-temperature form of case hardening, part distortion is minimal.
QPQ Liquid Nitriding – Process Capacities


Up to 42” long, 28” diameter.,
800 lb.

Process Selection and quality Control

Liquid nitriding requires precise control of the treatment process. Thermex operates under an ISO Certified Registered Quality Management System. Process quality control measures include:
  • Complete control of process sequence, including salt bath temperature and composition, polishing, and post-treatment parts handling
  • Test coupons of matching material are run with all nitriding loads. Coupons can then be used for metallurgical analysis in Thermex’s in-house metals testing laboratory. Random microhardness case depth surveys ensure that process specifications are being met.
Contact Thermex for more information on our liquid nitriding services.
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