Transformation of non-metal inclusions in ultra-low oxygen wheel steel during refining process

The formation and transformation of inclusions in high speed wheel steel during refining were studied in ultra-low oxygen steelmaking by LD-LF-VD-CC process. Sufficient aluminium was added to the experimental steel for final deoxidation during tapping, and refining slag with strong deoxidation, high basicity and strong reducibility was used during LF refining. The results show that the casting blanks are of high cleanliness and the total oxygen is only 7×10^-6. Oxide inclusions in the experimental steel have finished the transformation of Al₂O₃ → MgO·Al₂O₃ spinel → CaO-MgO-Al₂O₃ complex inclusions during LF refining, and the complex oxide inclusions obtained are liquid and easy to remove by collision, coalescence and flotation at steelmaking temperature. Residual oxide inclusions in the steel are CaO-MgO-Al₂O₃ system complex inclusions with a relatively lower melting point, which have a little deformability during hot-working and can improve the fatigue properties of high speed wheel steel effectively.