Experimental characterization and modeling of misorientations induced by plastic deformation at boundaries of annealing twins in austenitic steel

The evolution of misorientations at twin boundaries during hot deformations of austenitic steel was studied using electron backscatter diffraction and computer modeling with the purpose to explore the interrelation of this evolution with lattice rotations in grain interior. It was shown that a deformation-induced angular deviation from the initial twin misorientation turns out to be outside Brandon interval at many segments of the boundaries. The length fraction of these segments increases with strain, so that some twin boundaries transform to random ones at all their length. Statistical study shows that the most probable angular deviations are 9° and 13°, while the largest deviations are about 36° and 45° for the strain of 0.36 and 0.7, respectively. The experimental misorientation distributions were compared with theoretical ones computed using Taylor-type model. It was shown that deformation-induced misorientation changes are well described by the theory of polycrystals plasticity. At the same time, a discrepancy with the experiment occurs, which was proposed to be due to non-uniformity of grain lattice rotations.