Effect of Nitrogen and Stacking-Fault Energy on Twinning in [1-bar11] Single Crystals of Austenitic Stainless Steels

摘要

The dependence of critical shear stresses for twinning tau_(cr)~(tw) on the stacking-fault energy gamma_0, the nitrogen concentration C_N (wt alpha), and the test temperature has been studied for [1-bar11] single crystals of austenitic stainless steels upon tensile deformation. It is shown that tau_(cr)~(tw) ～ gamma_0/b_1 in nitrogen-free steels, while it exhibits a nonmonotonic dependence on the nitrogen concentration C_N in nitrogen-alloyed steels. An increase in tau_(cr)~(tw) at C_N = 0.3 wt alpha and its decrease at C_N >= 0.5-0.7 wt alpha are determined by the competition of two contributions to tau_(cr)~(tw), namely, a decrease in gamma_0 and a solid-solution hardening with increasing nitrogen concentration.