Application of deep cryogenic treatment in the nitriding process
Nitriding with subsequent heat treatment in combination with deep cryogenic treatment (DCT) produces nitrided layers with specific properties. Layers with unique properties result from the dissolution of subsurface layers of iron nitrides and subsequent nitrogen diffusion into the substrate during austenitisation. Fine precipitates of carbonitrides eventually form during DCT and the tempering process. Intermediate deep cryogenic treatment takes place between the quenching and tempering steps. This work is based on comparing novel nitrided layers with conventionally nitrided layers. In conventional thermochemical treatment, nitriding is the final operation. The experimental materials were 1.2379 (Czech Standard 19 573) cold-work tool steel and 1.3343 (Czech Standard 19 830) high-speed steel. The treatment methods were compared on the basis of hardness measurement, wear testing by the pin-on-disc method and metallographic analysis.