Grain-scale characterization of transformation textures

Orientation relationships during the austenite-to-ferrite (γ-to-α) phase transformation were investigated using electron back-scattered diffraction (EBSD) on a bainitic steel containing retained austenite. The steel was hot rolled within the austenite phase field, but below the `no-recrystallization' temperature, to two different strains. The observed orientation relationships between the bainite and retained austenite are expressed in Rodrigues–Frank space. The exact Kurdjumov–Sachs relation was never found. The local spread of orientation in the parent austenite (owing to deformation) is seen to be inherited by the bainite. This is attributed to the displacive mode of transformation to bainite. The influence of austenite prior deformation on the occurrence of variant selection was also studied. It is shown that a critical strain is necessary in order to observe a significant amount of variant selection.