Abstract：The properties of large spherical or bar-shaped inclusions, which was obtained by electrolytic extraction method in calcium treated steel, were investigated. Results of the scanning electron microscopy (SEM) and elemental composition analysis indicated that the large spherical- or bar-shaped inclusions originated from the clustered aluminum deoxidation product (Al2O3).A large number of small Al2O3particles have the tendency to form large-sized inclusion clusters, which further form a spherical- or bar-shaped by the complex flow field in the ladle. During the calcium treatment process, the modified inclusions can form a low-melting calcium aluminate, which form dense spherical-shaped inclusions during the solidification process of molten steel；the shape of the inclusions with insufficient modified still retain the morphology of Al2O3 inclusion. The ratio required for calcium treatment to modified Al2O3 inclusions is primarily affected by the content of S. Calcium aluminate has strong absorption and dissolution ability to S in molten steel. During the casting process, as the temperature of molten steel decreases, the Selement absorbed by the calcium aluminate is precipitated from the matrix in the form of CaS inclusions.
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2020, Vol. 55 
