WORK-HARDENING BEHAVIOR OF NITROGEN-ALLOYED AUSTENITIC STAINLESS-STEELS

This study analyses the plastic flow behaviour of types 316L and 316LN austenitic stainless steels. The following features are shown. (i) The yield stresses vary quasi-linearly with the nitrogen content. This is attributed to the linear variation in the thermal component with the interstitial concentration, according to the Friedel model. (ii) The monotonic work hardening of these steels can be modelled by the modified Ludwik model proposed by Ludwigson: sigma = K1-epsilon-n1 + DELTA, which takes into account the positive deviation from the Ludwik relation, which appears below a transient strain epsilon-L. This transition corresponds to a change in the dislocation slip mode, essentially planar below epsilon-L and multiple above epsilon-L. (iii) The influence of nitrogen on Ludwigson's modelling parameters is adequately explained by the fact that the nitrogen favours planar dislocation slip in the austenitic stainless steels.