Microstructure,Texture Evolution And Recrystallization Control Of 27Q120 Medium Temperature Grain-oriented Silicon Steel

The grain-oriented silicon steel with high magnetic induction and low iron loss is widely used to produce transformer core and stator core of large generator,and it is an indispensable soft magnetic material for the electricity,electronic and military industry.The slab must be reheated above 1350?when traditional grain-oriented silicon steel is produced,so that the coarse MnS and AlN in the slab are redissolved into the matrix,after that fine and dispersive inhibitors are precipitated during the hot rolling process,thus the primary recrystallized grain size can be controlled due to the strong pinning effect of the inhibitors.However,high temperature reheating leads to almost 5%of the burning loss and a series of problems,such as energy waste,low yield and unstable magnetic properties.At present,reducing the slab reheating temperature has become a research hotspot.In this paper,the medium temperature heating process was used to industrialize the production of common grain-oriented silicon steel,and the structure,texture and inhibitor evolution in different processes were studied.On this basis,the heating rate during high temperature annealing was studied,and the effect of heating rate on secondary recrystallization process was discussed.The results show that:?1?The microstructure of the hot rolled sheet is mainly divided into three areas:recrystallization zone of surface layer,fiber zone of central layer and intermediate transition layer.After increasing the hit rate of finishing temperature and coiling temperature,the average grain size of the surface layer is increased from 42.81?m to43.92?m,the proportion of the surface layer is increased from 17%to 44%,and the proportion of central layer is decreased from 38.67%to 33.19%.The content of Goss texture at the surface layer in the hot rolled sheet is increased from 3.65%to 7.80%,and the average diameter of inhibitors is decreased from 13.92nm to 9.08nm,Zener factor is increased from 218.97mm^-11 to 435.12mm^-1.The average grain size of the decarburized annealing sheet is decreased from 19?m to 16?m,and the average diameter of inhibitors are 21.63nm and 21.69nm respectively,there are little difference between them,but Zener factor is increased from 218.76mm^-1to 452.32mm^-1.The average grain size of the finished product is increased from 9.41mm to 17.57mm.?2?After the heating rate increased from 20?/h to 30?/h,the starting temperature of secondary recrystallization is decreased from 1000?to 990?,and both finishing temperature are 1025?.The finishing temperature of secondary recrystallization is 1050?when the heating rate is increased to 40?/h.With the increase of the heating rate,the starting temperature of secondary recrystallization is decreased,the finishing temperature is increased,the span of recrystallization temperature interval is increased.?3?When the temperature rises to 990?,the average diameter and distribution density of inhibitors at the heating rate of 20?/h are 17.52nm and 1.16×10¹⁵cm^-3respectively,the average diameter and distribution density of inhibitors at the heating rate of 30?/h are 18.61nm and 7.90×10¹⁴cm^-33 respectively.With the increase of the heating rate,the average diameter of the inhibitor increases and the distribution density decreases.?4?Compared with the heating rate of 20?/h,?-fiber and?-fiber distributed from{112}<110>to{111}<110>are observed at 925?at the heating rate of 30?/h,there are also a small amount of rotated cube texture,which disappears at 950?.?5?After optimization,the magnetic induction intensity reaches 1.885T,and the iron loss reaches 1.100W/Kg,which meets 27Q110 level.