Grain scale assessment of variant selection in a thermomechanically processed TRIP steel

Orientations of both the α and γ phases in a multi-phase com. steel were measured by means of electron backscatter diffraction (EBSD) techniques. Using the av. orientation of each austenite grain as the ref. 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 examd. 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 dissocn. of perfect dislocations. Reasonably good agreement was obsd. between the predictions and the observations. Possible explanations for some of the discrepancies are also presented.SCOPUS: bk.c