Variant selection during the transformation of deformed austenite in a niobium bearing TRIP steel

The transformation behavior of a 0.22wt%C-1.50wt%Mn-1.56wt%Si-0.045wt%Nb steel was studied after controlled rolling. Deformation below the no-recrystallisation temperature was employed to deform the prior austenite. During bainitic holding, some of the austenite was retained due to the enrichment of carbon in this phase. Using automated EBSD techniques, both the retained austenite and bainite orientations were measured and the orientation relationships between these phases are represented in Rodrigues-Frank space. The specific orientations predicted by the Bain, Kurdjumov-Sachs and Nishiyama-Wassermann relationships are compared with the measurements and the occurrence of variant selection is discussed.