Abstract:In order to improve the quality of Q235B continuous casting slab in a factory, the metallographic method, the no aqueous solution electrolysis method and the automatic inclusions scanning analysis system are used to find that the size of inclusions in the sample is mostly less than 20μm, small amount more than 20μm with irregular block shape. The inclusions less than 20μm are mostly endogenous Al2O3-SiO2 inclusions and pure Al2O3, the source is the deoxidation product produced during deoxidation, and the components of inclusions more than 20 μm are CaO-Na2O-Al2O3-SiO2 silicate and calcium aluminate, the source is the flux involved in the casting process and refractory materials washed by molten steel into molten steel.