In situ neutron diffraction study of the microstructure and tensile deformation behavior in Al-added high manganese austenitic steels

In situ neutron diffraction experiments were performed to measure the tensile deformation behavior of high manganese austenitic steels with different Al contents (0, 1.5, 2.0, 3.0 wt.%). Significant variations of peak shift, broadening and asymmetry of the diffraction peaks were observed in the plastic region with the measurement. Diffraction peak profile analysis was applied to determine microstructural parameters such as stacking/twinning fault probabilities, dislocation density and stacking fault energy (SFE). These parameters are quantitatively correlated to the yield strength, serrated flow and strain hardening rate during tensile deformation. The main results showed that the twin/stacking fault probability considerably decreases from 0.05 to 0.01 and dislocation density from 10(16) to 4 x 10(15) m(-2) as a function of Al addition, while SFE (gamma) increases from 20 to 45 mJ m(-2) with the relationship of gamma = 8.84 wt.% Al + 19.0 mJ m(-2). Such microstructural parameters are also in good agreement with the results of the misorientation and pattern quality map obtained by the electron backscatter method. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.