Surface cleanliness evaluation in Ti stabilised ultralow carbon (Ti-IF) steel

Abstract

The surface cleanness of Ti-IF steel, including head, transition, end and normal slabs, was studied by original position analyser. The content, number, size and porosity of inclusions on the surface were obtained. The results showed that: the contents of inclusions in head and end slabs were significantly higher than in normal or transition slabs and fluctuated significantly in non-steady state slabs within 3.5 mm of the surface; the porosity in 3.5 mm of slab surface was lower than other positions; the surface cleanliness order was normal slab>transition slab>end slab>head slab; a reasonable surface peeling thickness for non-steady state slabs was 3.5 mm. The energy dispersive spectroscopy showed that more lump Al₂O₃ existed in the head slabs, and slag entrapment inclusions also appeared frequently in the end slabs. The main effect factors for cleanness of the head and end slabs were reoxidation and slag entrapment.