Study On Microstructure And Texture Of Primary And Secondary Recrystallization In High Silicon Steel Thin Sheets

Compared with conventional silicon steel, Fe-6.5wt.%Si alloy have excellent soft magnetic properties:high permeability, higher resistivity and near zero magnetostriction. In present study, Fe-6.5wt.%Si thin sheets with thickness of 0.20mm to 0.50mm was successfully fabricated by rolling method. The texture optimization in primary recrystallization and the development of abnormal grain growth during secondary recrystallization in Fe-6.5wt.%Si sheets were studied by X-ray diffraction and electronic backscattered diffraction (EBSD).The texture of hot bands indirectly affects the cold rolling texture, and ultimately affects the recrystallization texture. Strong X fiber in hot bands and normalized bands results in the improved ? fiber in recrystallization texture.The hot band grain size have effect on the subsequent deformed microstructure, thus influence the formation and development of recrystallization texture.Under the condition of smaller hot band grain size, the deformation behavior tend to be homogeneous due to higher grain boundary coordination, and the intensity of recrystallization X fiber with the peak at {001}<310> was obviously improved; while the hot band grain size was increased, due to the increase of deformed inhomogeneity, ? grains were observed to nucleate mainly at shear bands within deformed{111}<112> grains based on analysis of EBSD, and the intensity of ? fiber was obviously improved.The components and intensity of recrystallization textures were similar among different annealing processes, the main texture were both consisted of ? and ? fibers. The maximum intensity of ? fiber texture with the peak at{001}<410> was closed to each other and the intensity of y fiber texture was very low for different annealing processes. Primary recrystallization texture was not strongly depend on the final annealing system, but closely related to the rolling process parameters.As to the effect of grain size after intermediate annealing, the intensity of ? fiber was increased with the increase of intermediate grain size, and this phenomenon was attributed to the increase of shear banding. Changing the heating rate, the intensity of ? fiber with the peak at {210}<001> was slightly lowered and y texture was increased with the increasing heating rate.In high silicon steel, under the condition of Cu2S as the main inhibitor, when the inhibitor content was lower, the abnormal grain growth was not observed and the initial grain size was larger; when the inhibitor content is higher, the abnormal grain growth was observed in local specific scope. In the scheme of adding Cu2S and NbC, the initial grain size is smaller and the abnormal grain growth was obviously observed with very low frequency. EBSD results showed that the grain experienced abnormally growth belongs to ?(<100>//RD) orientation. It can be deduced that several grains occasionally developed to secondary grain by means of volume fraction and size advantage. A wide range of secondary recrystallization phenomenon did not appear during high temperature annealing, the reasons mainly attributed to the unsatisfied control of microstructure, texture gradient and inhibitor content.