Calculation of nitrogen depth profiles in nitrided Fe-Mn and Fe-V

A model for the calculation of nitrogen depth profiles in nitrided steel based on trapping is presented. Trapping model calculations agree well with experimental nitrogen depth profiles for nitrided Fe–Mn (1.62 wt.% Mn) and Fe–V (0.55 wt.% V). Trapping depths of −0.30 eV and −0.55 eV are obtained for nitrogen trapped in Fe–Mn and Fe–V, respectively. Unrealistic knees in calculations using prevailing models based on precipitation are not observed in the trapping model predictions. The validity of the trapping model is discussed in view of the complicated microstructural changes occurring during the nitriding of steel (including e.g. precipitation). It is concluded that a realistic model for the nitriding of steel should incorporate both trapping and precipitation.