Recrystallization Texture Evolution During Grain Growth In Asymmetrically Cold Rolled Grain-oriented Silicon Steel

Silicon steels are important soft magnetic materials widely used in electric, electronic and military industries. Annealing and cold-rolled processes are the two key processes during which the significant change of microstructure takes place. Searching for the new method to efficiently control cold rolling and recrystallization texture can promote to establish the advanced technologies with independent intellectual property rights for high quality silicon steel production.In this thesis, asymmetric rolling was introduced to investigate the effects of speed ratio on cold rolling and recrystallization texture of grain-oriented silicon steel sheets by macro-and microtexture analysis.The obtained results are as follows:1. The symmetric and asymmetric rolling textures are mainly made up ofαandγcomponents. Asymmetric rolling has a larger impact on center layer and fast roll side layers with decreased{111}<110> and increased{111}<112>, while it has a smaller impact on slow roll side layers with the enhancedα. As a whole, asymmetric rolling shows a more obvious tendency to increase{111}<112>, and reduce{111}<110> andαas the speed ratio is raised.2. Under different rolling process, the first recrystallization textures are all composed ofη, {100},{111}<112> andαcomponents. As the recrystallization proceeds, the intensity ofηdecreases slightly in the symmetrically rolled sheet while increases in the asymmetrically rolled sheet;{111}<112> is weakened and enhanced in the symmetrically and asymmetrically rolled sheet respectively;{100} andαcomponents remain almost constant both in the symmetrically and asymmetrically rolled sheets.3. Asymmetric rolling has some impacts on the intensity and the distribution through thickness of recrystallization texture components.(1)ηtexture component. The lowest intensity appears at center layer under both symmetric and asymmetric rolling; the intensity of the slow roll side is higher than that of the fast roll side in the asymmetrically rolled sheet, while the intensity of the surface is higher than that of the 1/4 layer in the symmetrically rolled sheet. Generally, asymmetric rolling increasesη. The effect of asymmetric rolling stems mainly from the change of the cold-rolled y especially (111) <112> component due to the induced through-thickness shear strain, but two large shear strain seems not benefit forηcomponent.(2){100} texture component. Asymmetric rolling affects recrystallization{100}<011> component through rolling{100}<011>, and its effect on{100}<001> component is similar to theηcomponent. Asymmetric rolling tends to lower the{100} component on the whole.(3){111}<112> texture component. Asymmetric rolling reduces recrystallization{111}<112> component of center layer and fast roll side layers by weakening cold rolling a and y, resulting in the decrease of recrystallization{111}<112> component generally.(4) a texture component. Asymmetric rolling reduces the recrystallization a of the center layer and fast roll side layers while increases it in the slow roll side, so that an overall slight effect on a occurs.4. Accoring to microtexture analysis, asymmetric rolling reduces recrystallization {111}<112> through lowering nucleation rate, and enhancesηby increasing the nucleation rate and growth rate (space). The asymmetric rolling of 1.125 speed ratio increase{100} component by the increase in nucleation rate in spite of the deceasing growth rate (space) with the increase of speed ratio. By means of lowering growth rate (space) and increasing nucleation rate, asymmetric rolling affects the recrystallization a texture very slightly.