Study On Microstructure Evolution,Precipitation Behavior And Magnetic Properties Of High Grade Non-Oriented Silicon Steel

Non oriented silicon steel with high magnetic induction and low iron loss is the key material of high-efficiency motor.Researchers at home and abroad regard reducing core loss as an important research content to optimize the magnetic properties of non oriented silicon steel.This paper mainly takes the non oriented silicon steel hot-rolled plate of TISCO as the research object,and mainly studies the effects of the morphology,size,quantity and distribution of precipitation in the normalized plate and annealed plate of non oriented silicon steel treated by different normalizing processes on its microstructure and magnetic properties.The main conclusions of this paper are as follows:（1）When it is in the same equilibrium solid solubility product,Mn S takes precedence over Al N.Al N and Mn S precipitated first by dislocation nucleation mechanism inαphase region,and precipitated first by grain nucleation mechanism in（α+γ）two-phase region.Because the relative nucleation rate of grain boundary nucleation is large,and corresponds to the minimum critical nucleation work and faster initial precipitation time,Mn S precipitated mainly by grain boundary nucleation inγphase region.（2）The normalized samples and hot rolled samples after low-temperature normalizing treatment did not completely recrystallize.When the normalizing temperature increased to 950℃,the grains of the normalized samples completely recrystallized and the microstructure uniformity was great.After proper normalization treatment,the non-uniformity of longitudinal structure of hot rolled samples can be improved.（3）AlN and AlN-MnS composite phases are the main precipitations in the normalized samples treated by different normalization processes and the finished annealed samples.The N_Aand f of precipitations in normalized samples decreased with the increase of normalization temperature when the normalization treatment time was fixed,and the change was the most obvious at950℃;When the normalization temperature is constant,the change with the extension of normalization treatment time is roughly the same as that caused by the increase of normalization temperature,but the degree is slightly lower than the latter.The precipitates in annealed samples treated by different normalization processes will agglomerate and grow obviously,but their distribution density and volume fraction hardly change with the change of normalization process.The pinning force of micron precipitation relative to grain boundary is one order of magnitude smaller than the driving force of grain growth.The finished annealed samples treated by 950℃×5 min normalization process have the largest proportion of Goss texture components,and their magnetic properties are the best.B₅₀is 1.72 T and P_15/50is 5.85 W/kg.