Estimation of Nitrogen Concentration Distribution for Carbonitrided SUJ2 Steel

Abstract

We have been investigating the nitrogen penetration mechanism carbonitriding into high carbon chromium bearing steel JIS-SUJ2 on carbonitriding processes. Assuming that the penetration mechanisms of nitrogen and carbon are the same, we developed a calculation method in order to estimate nitrogen concentration distribution profiles, which are based on our through experimental data. In our method, the dependencies on carbon activity, partial pressures of H₂ and undecomposed NH₃, and diffusion coefficient of nitrogen are taken into consideration. It was confirmed that the nitrogen concentration distribution profiles predicted by our method agreed well with the experiment results under various conditions. Hence, we deduce that our method is effective in a practical range on carbonitriding processes.