Abstract: The clogs in SEN and inclusions in steelmaking process were analyzed by electron microscope, energy spectrum and phase analysis equipment. The results show that the large fluctuation range of mold level in W800 low aluminum non oriented silicon steel casting process is mainly caused by the accumulation of Al₂O₃ inclusions in the submerged nozzle. From RH ending to tundish, with the increase of slag oxidizability, the number density of Al₂O₃ inclusions increases gradually. Meanwhile, when w(CaO)/w(Al₂O₃) is less than 1.7 in slag, with the increase of w(CaO)/w(Al₂O₃), the activity of FeO decreases, and the number density of Al₂O₃ inclusions also decreases gradually. The addition of Al₂O₃ inclusions mainly come from the secondary oxidation of molten steel by top slag. The argon blowing flow of the stopper is small, and the inclusions will gather at the nozzle. Excessive argon blowing flow will cause large fluctuation range of mold liquid level. Proper stopper argon flow can effectively control the fluctuation range of mold liquid level. Through slag composition control and stopper argon flow adjustment, the cleanliness of molten steel is significantly improved, the number density of inclusions in tundish molten steel is reduced from 0.41/mm² to 0.35/mm², the compliance rate of mold liquid level fluctuation within ±1.5 mm is significantly increased, and the compliance rate is stable at more than 90 %.

Key words: non-oriented silicon steel, liquid level fluctuation, clogging, inclusion