Abstract: The transition of non-metallic inclusions of IF steel produced by SGJT during RH refining and tundish was investigated. Molten steel samples were taken from 2 industrial heats systematically， and the compositions， size distribution and number of the inclusions were analyzed using Aspex scanning electron microscopy. The results showed that Ti alloying and reoxidation of molten steel results in the formation of Al₂O₃-Ti_○xO inclusions， then these inclusions are transformed into Al₂O₃ inclusions during RH refining， which is in agreement with thermodynamic calculation. In addition， Al₂O₃ inclusions could be the nucleus of Al₂O₃-Ti_○xO that wraps up them， and steel droplets outside enters into the interior of the inclusions in the transformation from Al₂O₃-Ti_○xO to Al₂O₃， so steel droplets exists in the interior of Al₂O₃ inclusions.

Key words: IF steel, nozzle clogging, inclusion, reoxidation, holding time