The nature of the high work-hardening rate of nitrogen-bearing steels was examined, with focus on the stacking-fault energy. The dislocation configuration and the width of dissociated dislocations were evaluated in various types of austenitic stainless steels with and without nitrogen, using the weak-beam method. Nitrogen additions resulted in a change in the dislocation configuration from tangled to planar. Nitrogen was found to increase the stacking-fault energy rather than decrease it, as reported previously, and the stacking-fault energy could be formulated as a function of the chemical composition:

SFE(mJ/m2) = 5.53 - 0.16(wt%Cr) + 1.40(wt%Ni) + 17.10(wt%%N)

These results indicated that dislocation planarization by nitrogen additions was inadequately explained in terms of stacking-fault energy.

Weak Beam TEM Study on Stacking Fault Energy of High Nitrogen Steels. M.Ojima, Y.Adachi, Y.Tomota, Y.Katada, Y.Kaneko, K.Kuroda, H.Saka: Steel Research International, 2009, 80[7], 477-81