【作者】 刘涛；

【导师】 宋守许；

【作者基本信息】 合肥工业大学 ， 机械设计及理论， 2019， 硕士

【摘要】 本文在研究弯曲应力和轧制对旧硅钢磁性能影响实验中,利用光学显微镜、X-射线残余应力仪、SEM、XRD、EBSD、显微硬度仪等检测设备,系统研究了残余应力和退火对磁畴结构、析出相、硬度和织构的影响以及轧制工艺和再结晶过程中的微观织构特征形成规律,得出以下结论:随弯曲角度增大,硅钢的磁性能逐渐恶化,从0°变化到18°时,损耗上升了23.2%,剩余磁感、磁导率减小,矫顽力增大;弯曲应力随变形角度增大而增大,硬度也呈现略微上升趋势;随变形角度增大,磁畴壁的宽度及相邻磁畴壁的间距缩小,磁畴种类增多。对弯曲10°展平后的硅钢进行900°C保温4h后,{110}<001>织构强度相对升高但各试样强度很低,α-和η-fiber密度略高,磁壁间距增大,磁畴细化,细化率达到37.1%;随变形角度的增加和保温时间的延长,大量90°畴和180°畴转变为“岛屿畴”;试样高温退火后析出相较未处理试样显著粗化,粒子分布更加均匀。试样退火后,磁导率上升,铁损减小,磁性能较废旧硅钢明显提升,在900°C时损耗最低为1.01 W·kg^-1。在相同的冷轧条件或相同的温度下,与旧硅钢相比,制备所得试样的磁畴形态发生了较大变化,磁畴壁长度增长,单位面积上磁畴密度变大,磁畴细化明显;相同条件下（950°C下5min）退火时,随着压下率从28.6%增加到40%,γ-fiber的含量逐渐减小到6.6%,{110}再结晶织构逐渐增加,Goss织构的强度达到22.2;压下率34.3%下,随着温度从800°C升高到950°C,γ-fiber的含量逐渐减小到13.8%,{110}再结晶织构逐渐增加,Goss织构的强度为14;当压下率40%、950°C保温5min后样品的磁性能最好,较原始硅钢P_1.5/50降低了0.478W·kg,B₅₀提高了0.052T。一次斜轧（57%）后的再结晶晶粒尺寸比两次斜轧后的晶粒尺寸更大、更加均匀。虽然采用不同的冷轧方法（一次和两次斜轧）,但所得到的退火织构都具有相似的特征,不同之处在于γ-fiber和η-fiber的相对强度。一次斜轧（57%）退火显著降低了γ-fiber的强度,促进了η-fiber的强度。当斜轧角度为60°时,能够获得最强Goss织构和最大体积分数的{110}+{100}织构。新Goss晶粒除了可以在{111}变形晶粒内形核,也可在{113}变形晶粒晶界、{113}和近{100}变形晶粒晶界间形核。一次斜轧能较好的改善旧硅钢的磁性能（B₈）,磁感应强度在1.712-1.742T之间,且60°斜轧能获得最高的磁感应强度1.742T。更多还原

【Abstract】 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 ofα-andη-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）,theγ-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%,theγ-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 theη-fiber and the Goss texture component and the weakening ofγ-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）.更多还原