Crystallographic examination of the interaction between texture evolution, mechanically induced martensitic transformation and twinning in nanostructured bainite

In this work, the microstructural and crystallographic bulk changes of a high-C nanostructured bainite under tensile testing have been evaluated. The influence of the mechanically-induced transformation of the C-enriched retained austenite into α martensite and other deformation mechanisms on the texture evolution has been analysed by electron backscatter diffraction (EBSD). Additionally, the undeformed and the deformed conditions have been examined by electron channelling contrast imaging (ECCI) and transmission electron microscopy (TEM). Results reveal the presence of plate martensite and suggest a strong variant selection during the transformation, mainly responsible for the texture observed. Mechanical twinning in austenite seems to be basically the mechanism of accommodation of the displacive bainitic transformation, while some direct interaction with the applied stress also appears.