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MM: Fachverband Metall- und Materialphysik
MM 46: Mechanical Properties III
MM 46.1: Talk
Friday, March 18, 2011, 10:30–10:45, IFW D
Appearance of dislocation mediated and orientation selective deformation twinning in a bimodally textured FeMnNiCr alloy — •David Geissler1,2, Jens Freudenberger1, Alexander Kauffmann1,2, Maria Krautz1,2, Jörg Eickemeyer1, and Ludwig Schultz1,2 — 1IFW Dresden, PF 270116, 01171 Dresden, Germany — 2TU Dresden, 01062 Dresden, Germany
The deformation behaviour of low stacking fault energy (SFE) materials is of great interest to Fe-Mn based austenitic steel research. By comparing the microstructural and texture evolution with tensile stress-strain response of a Fe-24Mn-7Ni-8Cr (mass percent) alloy a slip-dominated deformation process and, at a later stage of deformation, twinning induced plasticity (TWIP) is observed. The annealed starting material exhibits a bimodal fiber texture and the occurrence of TWIP is texture sensitive, i.e. deformation twinning is only observable in grains of one texture component. Based on these experimental results, a model is presented, which reflects an orientational and configurational peculiarity of fcc stacking faults bound by two Shockley partials. With this model the onset point of twinning is reflected by the starting point of stacking fault growth, i.e. movement of the leading partial and stopping of the trailing partial. Calculations based on this model allow to compatibly describe the mechanical behaviour from tensile testing with respect to the microstructural evolution. Furthermore a reasonable SFE of 12.2 mJ per square meter can be extracted from the test data by application of the model assumptions.