Effect Of Deformation Mode On The Formation Of Primary Recrystallization Texture In Grain-oriented Silicon Steel

Grain-oriented silicon steel sheets are indispensable soft magnetic materials in electric, electronic and military industries, as commonly used in hydroelectric power plant generators and electric motors. The magnetic properties of grain-oriented silicon steels are closely related to recrystallization texture. Thus, the exploration of a new method for more effective texture control can provide a new approach to optimize the magnetic properties of grain-oriented silicon steels.In present thesis, asymmetric rolling was introduced into cold rolling process of grain-oriented silicon steel sheets. The 0.3mm thick cold rolled sheets were prepared with speed ratios of 1,1.125 and 1.19 asymmetric rolling in all passes. Afterwards, vacuum annealing was carried out at 600,620,640,835℃for 5 minites. The textures after cold rolling and during primary recrystallization process were investigated by Electron Back Scattered Diffraction (EBSD) and X-Ray diffraction (XRD) methods.Deformation textures produced by symmetric and asymmetric rolling are both composed of a and y fibers, with the intensity peaks at{001}<110> and{111}<110>, respectively. Asymmetric rolling decreases the intensities of deformation textures in the middle and fast roller side layers, but increases in the slow roller side layers. Asymmetric rolling generally weakens the deformation textures, and this effect is more obvious with the increasing speed ratio. Shear bands are inclined to the rolling plane at approximate angles of±20°and±35°, the area fraction of the grains with shear bands increases with speed ratio.The textures of early stage primary recrystallization in the sheets by different rolling methods consist ofα,η,γand{100} fibers. Asymmetric rolling does not remarkably change the development characteristics of textures as primary recrystallization proceeds:a and{100} fibers are continuously weakened whileηfiber is strengthened; {111}<112> component is increased but the{111}<110> component are decreased, leading to the intensity peak of y fiber towards{111}<112>; as the intensity of cold rolled y fiber and density of shear band increase, the intensities of y andηfibers are strengthened. Compared with symmetric rolling, asymmetric rolling can strengthenηand y fibers, and promote the{111}<112> to be the peak of y fiber. At the early stage of recrystallization, the nuclei of y orientation preferentially form within the deformed y bands as well as the boundaries between deformed a andγbands.