Mechanical and microstructural investigations of nitrided Fe-Cr layers

Nano-indentation measurements were carried out on nitrided Fe-Cr alloys (1 and 3 wt% Cr) in order to determine local micro-mechanical properties. The method recently developed on nitrided 32CrMoV13 steel was applied to the Fe-Cr alloys. Evolution of micro-yield stress through the nitrided layer was correlated to microstructural parameters (volume fraction of CrN precipitates, diameter of precipitates, etc.) investigated and statistically analyzed by transmission electron microscopy (TEM). The results show that the mechanical behavior of the nitrided layer for both alloys studied can be described using the Orowan model of precipitation strengthening.