Study of Micro-inclusion in O5 Sheet Steel Produced by BOF-RH Route

T[O]and[N]and the type,source,quantity and composition of micro inclusions during the production route of O5 sheet steel(pre-desulfuration → BOF → ladle slag modifier → RH → CC) had been,analyzed.The results showed that T[O]is 25.67×10^-6,[N]was27×10^-6,and the number of micro-inclusions per mm²was 2.66 in slab.The main types of micro-inclusion in casting billet were TiN,TiO₂-FeS and Al₂O₃ inclusions and their contents were 30%,24.55%,20.91% respectively.After RH vacuum break the molten steel still had high T[O],[N]and large quantity of micro-inclusions,indicating insufficient RH vacuum treatment.Floating and removal of inclusions in steel was less effective,thus improving the ladle top slag inclusions adsorption performance is one way to improve the quality of steel.slab,nearly half of micro-inclusions in slab were irregular shape,therefore,fully liquefying,aggregation and floating of micro inclusion are essential to improve the quality of O5 sheet steel.