Effect Of Deformation And Annealing On Microstructure And Magnetic Properties Of Nonoriented Silicon Steel

In this experiment of studying the influence of bending stress and rolling on the magnetic properties of used silicon steel,effects of residual stress and stress relief annealing on magnetic domain structure,precipitated phase,hardness and macroscopic texture as well as micro-texture characteristics and formation rules during rolling and recrystallization were systematically studied by means of optical microscopy,X-ray residual stress meter,SEM,XRD,EBSD and microhardness tester.Concluded as follow:The ac/dc performances of the silicon steel significantly worse and iron loss of silicon steel varying from 0°to18°deteriorates by 23.2%,residual magnetic induction intensity and magnetic permeability decreases,coercive force increases;The bending stress increases with the angle rises,hardness of the silicon steel also shows a trend of slight rise;At the same time,along with the deformation increases,the kinds of magnetic domain increased,magnetic wall width and the spacing between adjacent magnetic wall narrow as well.After annealing of the silicon steel deformed in 10°with a temperature of 900°C and holding 4h,intensity of Goss texture is relatively increased,but the intensity of each sample is very low,the textures density of?-and?-fiber are slightly higher,magnetic wall spacing increases,magnetic domain refines and its refining rate reached37.1%.When the deformation and holding time increase,a plenty of 90°domain and180°domain evolve into“Island domains”;After annealing in high temperature,the precipitates are significantly coarser than that of untreated samples and the distribution of particles is more uniform.After annealing,as the iron loss reduced and magnetic permeability increased,magnetic properties can be significantly improved compared with that of used silicon steel,the lowest loss can be 1.01 W·kg^-1 at about 900°C.The magnetic domain could be transformed vastly compared with the used silicon steel when the specimens were prepared through the same cold rolling and annealing temperature conditions.The length of the magnetic wall and the density of magnetic domain per unit area were boosted,and the magnetic domain refinement was exceedingly apparent.Under the same annealing condition?at 950°C for 5 min?,the?-fiber was gradually decreased to 6.6%and the{110}recrystallization texture was gradually enhanced with increased reduction from 28.3%to 40%.The intensity of the Goss texture reached a maximum of 22.2.For the cold rolling reduction of 34.3%,the?-fiber gradually decreased to 13.8%and the{110}recrystallization texture was gradually enhanced with increase in the annealing temperature from 800°C to 950°C.Moreover,the intensity of Goss texture reached 14.The sample prepared through cold rolling with 40%reduction and annealing at 950°C for 5 min exhibited the most desirable magnetic properties.The magnetic induction B₅₀ value of the specimen was increased by 0.052 T,and the core loss P_1.5/50 was reduced by 0.478 W/kg compared with the initial specimen.The grain size after one skew rolling?57%?was larger and more homogeneous than the grain size after the two skew rolling.Although with different cold rolling methods?one and two skew rolling?,the resulted annealing textures all had similar features.The difference was the relative intensities between the main texture.A significant feature of one skew rolling was the intensification of the?-fiber and the Goss texture component and the weakening of?-fiber.At an inclination angle of 60deg,a significantly strong Goss texture was produced,which was highest among all samples,and the maximum volume fraction of{110}+{100}texture can also be obtained.The new Goss grains were nucleated except at{111}deformed grains,and also formed at the grain boundary between two deformed grains with{113}orientation,and at grains boundaries between{113}and{100}deformed grain.One skew rolling can better improve the magnetic properties of used silicon steel?B₈?,and the magnetic induction is between 1.712 T and 1.742 T.The highest magnetic induction of 1.742 T can be obtained by one skew rolling?at an inclination angle of 60deg?.