Influence of hydrogen content in working gas on diffusion processes at ion nitriding of martensitic and austenitic steels

The effect of hydrogen content in working gas on diffusion processes at ion nitriding of martensitic and austenitic steels was investigated. Ion nitriding of martensitic and austenitic steel was carried out with containing various argon–nitrogen–hydrogen gas mixtures. The effect of hydrogen content on the thickness of the nitrided layer was studied. The ion nitriding was carried out at a temperature of 550°C for 6 hours. The structure and properties of nitriding layers was investigated by using cross-sectional scanning electron microscopy, Vickers microhardness tests and optical microscopy. The change of hydrogen content in working gas from 10 to 50% allowed to increase surface microhardness and thickness of nitriding layer. The effect of hydrogen content on diffusion process and existence of cracks, fractures, failures in nitriding layers was studied.