Evolution of Al-Ti-Mg-O Inclusions During Refining and Casting Process of Interstitial Free Steel

摘要

The evolution of chemical composition, size, proportion, and morphology of the Al-Ti-Mg-O inclusions during the steelmaking process of Interstitial Free (IF) steel from the RH to the Continuous Casting (CC) slab were investigated by means of Auto-SEM. Results showed that many of Al_2O_3 and MgO-Al_2O_3 type inclusions are modified by TiO_x, while most of their shapes are irregular due to the high melting temperature. The composition evolutions and melting characteristics of Al-Ti-Mg-O inclusions under different contents of [Al], [Ti] and [Mg] were estimated by using thermodynamic software Factsage 7.0. Resulted showed that estimated results are in good agreement with the analysis results of industrial samples. Both the Ti alloying and spontaneous enrichment would make a high Ti concentration environment that was in favor of the TiO_x existence. Moreover, more TiO_x component can modify MgO-Al_2O_3 spine inclusion into inclusions with a lower melting temperature.