Grain Scale Assessment of Variant Selection in a Thermomechanically Processed TRIP Steel
Orientations of both the α and γ phases in a multi-phase commercial steel were measured by means of electron backscatter diffraction (EBSD) techniques. Using the average orientation of each austenite grain as the reference frame, the orientation relationships between the two lattices were compared with the common orientation relationships (i.e. the Kurdjumov-Sachs and Nishiyama-Wassermann) in Rodrigues-Frank space. The occurrence of variant selection in individual austenite grains was examined using a recent dislocation-based model. This model considers the role of the slip systems that were active during prior deformation, as well as those of in-plane reactions, cross-slip and the partial dislocations that are linked to specific variants. It also unites the competing K-S and N-W relationships through the dissociation of perfect dislocations. Reasonably good agreement was observed between the predictions and the observations. Possible explanations for some of the discrepancies are also presented.
T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran
Y. L. He et al., "Grain Scale Assessment of Variant Selection in a Thermomechanically Processed TRIP Steel", Materials Science Forum, Vols. 539-543, pp. 4762-4767, 2007