3. Liquid treatment: case-hardening and cyanidation (carbonitriding) in a salt bath

The liquid medium is a bath of molten salts rich in carburizing or carbonitriding products, in which the parts are immersed. This process, which was highly developed until the 1970s, has been greatly reduced, and has even disappeared in countries subject to environmental regulations.

The main reasons for this are linked to the cyanide nature of these baths. Cyanide-free formulations have been developed to overcome this problem, but the relative effectiveness of these formulations and the constraints of even cyanide-free salt baths have prevented this technique from maintaining its position in relation to gaseous processes.