Effect of initial aluminium-oxygen concentration product on alumina-based inclusions in high carbon Al-killed steels during the ladle refining process

The effect of different aluminium-oxygen concentration products at the start of deoxidation on the evolution of alumina-based inclusions in high carbon Al-killed steels during the ladle refining process was investigated. Results showed that the higher aluminium-oxygen concentration product at the start of deoxidation, the higher area fraction and the number density of large-sized inclusions before the slag melting, then clustered alumina-based inclusions gradually became ripening. Thermodynamic equilibrium results indicated that initial contents of the [O] were 100, 200, 300 and 400 ppm in the molten steel, then contents of the [O] at the final reaction equilibrium were 4.6, 4.9, 5.8 and 9.5 ppm, respectively. The relationship between oversaturation and size of Al2O3 inclusions showed that the larger the critical radius of nucleus, the lower the oversaturation. Meanwhile, the evolution mechanism of alumina-based inclusions during the LF refining process was also revealed.