Microstructure and Microtexture Evolution of a TRIP-Assisted Steel after Small Deformation Studied by EBSD Technique
TRIP-assisted steel with a composition of 0.2%C, 1.5%Mn, 1.5% Al was studied in the undeformed state and after the application of 20% tensile strain parallel to rolling the direction of the sheet. The microstructure and microtexture of the steel sheets were examined in detail by means of electron backscattered diffraction (EBSD) in order to quantify the microstructural constituents and to study the strain distribution. The evolution of the microtexture and the distribution of the specific texture components between the BCC and FCC phases were studied as a function of the external strain. The strain localization and strain distribution between the structural constituents were quantified on the base of the local misorientation maps. The full constraint Taylor model was used to predict the texture changes in the material and the results were compared to the experimental findings. Comparing the local misorientation data it was found that at low strains the ferrite accommodates approximately 10 times more deformation than the retained austenite. The strain localizes initially on the BCC-FCC phase boundaries and then is spread in the BCC constituents (ferrite and bainite) creating a deformation skeleton in the BCC phase. The composite-like strengthening behaviour in TRIP-aided steel at 20% deformation might be expressed by the decreasing free path of dislocations in ferrite due to the enlarging and thickening of the multiphase skeleton as plastic deformation progresses, without changing significantly the main texture components in the material.
P. B. Prangnell and P. S. Bate
R. H. Petrov et al., "Microstructure and Microtexture Evolution of a TRIP-Assisted Steel after Small Deformation Studied by EBSD Technique", Materials Science Forum, Vol. 550, pp. 265-270, 2007