Distribution of Inclusions in a IF Steel Continuous Casting Slab Casted During SEN-Clogged State

Inclusions in an interstitial-free (IF) steel slab from the loose side to the fixed side of the width center were detected to investigate the distribution of inclusions in the slab under the nozzle clogging state. The total oxygen (T.O) content of the slab was 11.07 ppm, and the total nitrogen (T.N) content of the slab was 24.96 ppm. Endogenous inclusions in IF steel were Al₂O₃ inclusions; TiN inclusions were precipitated with Al₂O₃ as the core during the cooling process of slab. In the thickness direction from the surface to the center of the slab, the area fraction of inclusions increased from 25.32 ppm to 267.78 ppm, and the maximum value of the inclusion area fraction was 405.62 ppm below the center of the slab. Due to the small cooling rate at the center of the slab, the number density of TiN larger than 10 μm reached 1.64 #/mm². Under the condition of nozzle clogging, the level fluctuation was large in the mold; contrary to the normal condition, the number density of inclusions at the fixed side of the slab was larger than that at the loose side.