By comparing the microstructural and textural evolution with the tensile stress-strain response of an Fe-24Mn-7Ni-8wt%Cr alloy, a slip-dominated deformation process and, at a later stage of deformation, twinning-induced plasticity were detected. The occurrence of deformation twinning was texture-sensitive and occurred only in the <111> fibre texture component. Based upon these experimental observations, a model was developed which reflected an orientational and configurational peculiarity of face-centred cubic stacking faults bordered by two Shockley partials. Using this model, the onset point of stacking-fault growth (movement of the leading partial and stopping of the trailing partial) was evaluated. This reflected the formation of twins in the sense that a twin was regarded as an arrangement of stacking faults on every consecutive slip plane. Based upon the tensile test results, a model-compatible description of the mechanical behaviour was possible and a reasonable stacking-fault energy of about 8mJ/m2 was calculated for the onset of partial dislocation breakaway (onset of deformation twinning).

Appearance of Dislocation-Mediated and Twinning-Induced Plasticity in an Engineering-Grade FeMnNiCr Alloy. D.Geissler, J.Freudenberger, A.Kauffmann, M.Krautz, H.Klauss, A.Voss, J.Eickemeyer, L.Schultz: Acta Materialia, 2011, 59[20], 7711-23