Inclusions in the surface layer of IF steel slab

The sizes,quantity,distribution,and compositions of inclusions in the surface layer of IF slab produced with the BOFRH-CC process were synthetically studied by means of total oxygen and nitrogen content analysis,optical microscopy,scanning electronic microscopy (SEM),energy dispersive X-ray spectroscopy (EDS),and metal original position analysis (OPA). It is found that reoxidation is serious during the unsteady casting period,and the number of large size inclusions increases obviously; the number of inclusions at the position of 1/4 in slab width is higher than that at the edge and the center of the slab; with the increase of the distance to the inner arc surface,the average size of the inclusions drops and the ratio of the inclusions larger than 10 μm decreases; the number and size of inclusions in the surface layer are obviously larger than those in the inner of the slab,and the amount of inclusions at the position of 6 mm from the inner arc surface is the highest.