Improvement of properties of steels applying salt bath nitrocarburizing with post-oxidation

The comparative testing of properties for the steel grade Ck45 (AISI-1045) after salt bath nitrocarburizing (TENIFER process) without and with post-oxydation (TENIFER QPQ process) was performed. To evaluate the effects of post-oxidation on differently nitrocarburized specimens metallographic testing, investigation of chemical composition through the sample cross-section, testing of hardness, roughness, corrosion and tribological properties were carried out. The results indicate that post-oxidation has no significant effect on the hardness decrease, it lowers, however the friction coefficient and improve the corrosion resistance in comparison to the non-oxidized steel. That enhancement in properties is effect of the formation of iron oxide layer on the compound zone during the cooling after nitrocarburizing and especially during the subsequent treatment in the oxidizing bath.