Abstract：High-grade non-oriented silicon steel has a higher pursuit in magnetic properties. The inclusion is one of the main factors affecting the magnetic properties, and has been paid much attention by more and more researchers.WV1900 was selected for the object of study. The microstructure of inclusions in silicon steel and its evolution law with the increase of annealing temperature were investigated by the means of dual-beam system, energy spectrometer and Dragonfly three-dimensional reconstruction software system. The results showed that the main types of inclusions were AlN, MnS, AlN-MnS, AlN-Al2O3, MnS-Al2O3 and AlN-MnS-Al2O3. The morphology of three-dimensional space showed that AlN, MnS and AlN-MnS were easily precipitated with Al2O3 as the nucleation core. Moreover, AlN-MnS was the nucleation precipitation of MnS attached on AlN. With the increase of annealing temperature, the inclusions showed a change rule of precipitation-growth-reprecipitation-dynamic equilibrium between precipitation and solid solution. In order to improve the magnetic properties of the finished product, the annealing temperature at 990-1 000 ℃ was recommended. In this temperature range, the total number of inclusions was low, and the inclusions with a size of (0,1] μm also reached a low value, which reduced the influence on the magnetic properties of the finished product to a certain extent. The research results of inclusion type, space morphology and precipitation law in the study could provide a technical support for the formulation of the annealing process and the improvement of the magnetic properties of the non-oriented silicon steel.
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