TEXTURE AND M1CROSTRUCTURE EVOLUTION IN A Fe-Si CGO SHEET DURING THE PROCESSING ROUTE BEFORE SECONDARY RECRYSTALLIZATION

摘要

The present work deals with the origin of the Goss grains present in the primary recrystallized structure. Consequently, the generation of the main texture components and their associated microstructures was followed from the hot rolled to the primary recrystallized state at each step of the processing route. The texture was quantitatively characterized by X-ray diffraction and EBSD.In the hot rolled state, the microstructure is made up of bands of subgrains or recrystallized grains. Near the surface and a quarter of the sheet thickness (QST) the texture possesses a strong Goss component, its strength decreasing with increasing depth down to the center. Conversely, the a fiber texture components increase in intensity towards the center of the sheet.After the first stage of cold rolling, the strength of the Goss orientation drops down to the benefit of the y texture components, (111)[1-21] and (111)[-1-12]. From EBSD determinations, it is found that the Goss grains rotate mainly towards these orientations, the volume fractions of which become approximately equal to 15 % each. The a texture components are the major components at the center of the sample and do not significantly change until the last annealing treatment, when their volume fractions decrease noticeably.The second cold rolling step results in the stabilization of the (111)[1-21] and (111)[-1-12] orientations formed close to QST. Grains having these y texture orientations also show shear bands inclined 35-40° relative to the rolling plane. An interesting feature observed in the shear bands located in grains with the (111)[1-21] orientation is the formation of grains with either a (11 l)[1-10] orientation or the Goss orientation. Conversely, grains with a (111)[0-11] orientation appear only on shear bands located within grains with a (111)[1-21] orientation. It was also noticed that some Goss grains were present between lamellar grains too.With the last annealing, the strength of the a fiber decreases to the benefit of the (111) [1-21] and (111) [1-12] orientations and the random component, while the volume fraction of Goss grains becomes negligible.