Thermodynamic analysis of the short range order strengthening in Fe---Ni---Cr---N austenite

The effect of nitrogen-induced short range order and its change during plastic deformation on the plastic flow behavior of Fe---Ni---Cr---N austenite has been studied using a statistical thermodynamics model. The results show that the short range order makes a significant contribution to the strength of austenite, and that the reduction in its degree due to the passage of dislocations on the same slip plane can account for the occurrence of planar slip in the austenite with nitrogen. An analysis of the thermally activated behavior of the dislocation motion was conducted in order to quantify the temperature dependence of yield stress. It is found that, while the short range order gives rise to a somewhat larger temperature dependence of yield stress relative to that found in the conventional f.c.c. metallic materials, it still can not fully account for the measured values in the Fe---Ni---Cr---N austenite.