Research On Preparation Of Oriented High Silicon Steel By Efficient Annealing Mode

Fe-6.5 wt.%Si alloy is a perfect iron core material that combines the advantages of low iron loss,high magnetic permeability,and low noise at high frequency,because of its excellent properties such as high resistivity,low magnetic crystal anisotropy,and almost zero magnetostrictive coefficient.High silicon steel has low plasticity due to solid solution strengthening and ordered phases.In recent years,research on high silicon steel has mainly focused on solving the problem of rolling and forming,and has made certain breakthroughs.The secondary recrystallization texture control is the key to the excellent soft magnetic properties of oriented high silicon steel.Current researches on the secondary recrystallization of oriented high silicon steel have adopted slow-heating annealing process,which has problems such as long annealing cycles,large energy consumption,and high preparation cost.With the development of national environmental protection strategies such as green environment protection,energy conservation and emission reduction,it is necessary to prepare oriented high silicon steel with high efficiency and low cost,and to update the original long annealing process.Therefore,it is of great significance to use high efficiency annealing mode to prepare oriented high silicon steel.Compared with conventional grain-oriented silicon steel,oriented high silicon steel has problems such as less precipitation of traditional inherent inhibitors(MnS,MnSe,AlN,etc.),limited addition of grain boundary segregation elements(Sn,Sb,etc.),etc.,which makes it difficult to match the microstructure-textureinhibitor during high temperature annealing.In this study,NbC was used as an inhibitor and MnS was used as a reference.Oriented high silicon steel strip with strong η(<001>//RD)texture was successfully prepared using traditional hot rolling,cold rolling,and efficient annealing mode.X-ray diffraction and Electron Backscattered Diffraction(EBSD)were used to study the secondary recrystallization behavior and texture evolution during high temperature annealing.The main findings are as follows:(1)Developed the technology of manufacturing oriented high silicon steel strip in efficient annealing mode,which greatly improved the manufacture efficiency of oriented high silicon steel.The magnetic induction intensity B8 of the 0.22 mm thickness strip reaches 1.64 T.(2)The traditional inhibitor MnS is not suitable for oriented high silicon steel with efficient annealing,because it is difficult to effectively pin the matrix grains.The 0.06～0.09 wt.%NbC meets the requirements for the strength of the restraining force and the law of decay in the technology of efficient annealing to manufacture oriented high silicon steel.(3)Annealing temperature has an important influence on the development rate,completion degree and deviation angle of secondary recrystallization η texture.Annealing at 925～975℃,the secondary recrystallization completion is close to 100%,the secondary recrystallization rate increases with the increase of annealing temperature,and annealing at 950℃ the secondary recrystallization η texture deviation angle is the smallest.(4)The secondary recrystallization rate and texture deviation angle of high silicon steel is closely related to rolling reduction.The 73%reduction has the faster secondary recrystallization rate,and the secondary recrystallization η texture deviation angle is smaller.When the rolling reduction is increased to 81%,the secondary recrystallization rate and the degree of completion are the lowest,mainly due to the reduction in thickness,the surface grains grow faster and the secondary recrystallized grains reach the surface earlier,forming thermal groove.