Anti-corrosion potential of the low-pressure nitriding method for the iron alloys

This study aims to analyse the low-pressure nitriding method to determine its anti-corrosion protection potential. Components made of EN C20, EN 41CrAlMo7 and EN 42CrMo4 steels were low-pressure nitrided in a pure ammonia atmosphere at a pressure of 26 hPa. The nitrided layers formed were analysed in terms of structure, effective layer thickness, corrosion resistance and friction wear resistance. It was determined that an iron nitride layer with a phase composition of epsilon+gamma' and a thickness of not less than 10 mu m provides effective protection against the corrosive influence of the urban environment for up to 3 months, while layers with a thickness of not less than 14 mu m provide effective protection for up to 5 months. The iron nitride layer was found to increase the friction wear resistance of the nitrided steel. The wear that occurs within the iron nitride layer is linear. The wear process, after exceeding the thickness of the iron nitride layer, progresses to an accelerated wear phase, which ultimately leads to seizure.