Effect Of Secondary Recrystallization Magnetic Field Pretreatment On Microstructure And Properties Of CGO Steel

In the last few years,the production output of oriented silicon steel is rising gradually,the production process and production technology are improving gradually as well,and the market demand for product performance with high magnetic sensitivity and low iron loss is also rising.Therefore,how to break through this bottleneck has become the key problem concerned by many researchers.With the continuous innovation of many research methods,magnetic field treatment is gradually favored by researchers because of its clean and efficient nature,therefore,magnetic field annealing technology arises at the historic moment.In my thesis,low-intensity pulsed magnetic field pre-annealing experiments were carried out on CGO steel samples at the stage before the secondary recrystallization annealing after the second cold rolling,to explore the effects of applying pulsed magnetic field at different temperatures on the microstructure,texture and properties of oriented silicon steel.The microstructure distribution of the pre-annealed and the second recrystallization annealed specimens were observed and analyzed by metallographic microscope.X-ray diffraction(XRD)test method was used for analyzing the distribution condition of macroscopic texture of pulsed magnetic field pre-annealed specimens.The distribution condition of microstructure and texture of pulsed magnetic field pre-annealed specimens was got by electron backscatter diffraction(EBSD)test method,and the influences of pulsed magnetic field pre-annealing on misorientation,coincidence position lattice(CSL)and deviation angle of pre-annealed specimens were researched.Several control experiments were designed in the pulsed magnetic field pre-annealing stage,then the specimens after pre-annealing are subjected to high temperature annealing process.Magnetic properties such as magnetic sensation and iron loss of the samples after high temperature annealing were measured by TD8510 magnetic properties testing system.The effect of pulsed magnetic pre-annealing on the final magnetic properties of cold rolled CGO steel was analyzed.The average grain size of the specimens increases by up to 9% after pulsed magnetic field is applied in the pre-annealing stage.After the secondary recrystallization annealing,the grain size of the samples reached the centimeter level and all the samples had been recrystallized.Among them,mixed crystals appeared in the secondary recrystallization annealing samples pretreated by pulsed magnetic field.After pulsed magnetic field was applied,the proportion of small angle grain boundary(2 ～ 15 °)around Goss texture decreased,and the proportion of large angle grain boundary(> 15 °)was higher than that without pulsed magnetic field,which was favorable for Goss texture to absorb surrounding small angle grain boundary and grow up.Σ 3 and Σ 9 grain boundary volume fractions were close to those of the sample without pulsed magnetic field,and within a certain range,the ultimate magnetic properties were the best.After applying the pulsed magnetic field,the deviation angle of the sample decreases obviously,and the optimal deviation angle is 8～9 °.The magnetic field promotes {111}<112>,{001}<110>,{001}<100> texture,inhibits {112}<110> texture.The magnetic properties of secondary recrystallization annealing specimens pretreated by pulsed magnetic field are obviously higher than those of secondary recrystallization annealing specimens without pulsed magnetic field,and the magnetic strength can be grown by 9.58 %.Iron loss can be reduced up to 11.8 %.