| Summary: | The evolution of inclusions that contain Al, Mg, and Ti was studied through industrial-grade experiments. Field emission scanning electron microscopy, energy dispersive spectrometry, <span>inductively coupled plasma atomic emission spectrometry</span>, and FactSage software were used to analyze the evolution mechanisms of inclusions in Al-killed titanium alloyed interstitial free (IF) steel. The research found that the evolution of inclusions during the smelting process of IF steel is results in ‘<span>large sphere-like SiO<sub>2</sub>-CaO-FeO-MgO-MnO’ and ‘small cluster spherical FeO-MnO’</span> change to cluster-like Al<sub>2</sub>O<sub>3</sub> and irregular MgO·Al<sub>2</sub>O<sub>3</sub>, then change to Al<sub>2</sub>O<sub>3</sub>·TiO<sub>x</sub> and Al<sub>2</sub>O<sub>3</sub>, and finally change to Al<sub>2</sub>O<sub>3</sub>. It is difficult for Al<sub>2</sub>O<sub>3</sub>·TiO<em><sub>x</sub></em> to stably exist in the IF molten steel. It is the key to extend the holding time properly after Ruhrstahl Heraeus (RH) to ensure the removal of Al<sub>2</sub>O<sub>3</sub> inclusion. With the increase of Mg content, the change path of MgAl<sub>2</sub>O<sub>4</sub> inclusion in IF steel is that Al<sub>2</sub>O<sub>3</sub> changes to MgO·Al<sub>2</sub>O<sub>3</sub>, and finally changes to MgO. It is difficult to suppress MgO·Al<sub>2</sub>O<sub>3 </sub>spinel formation by controlling the oxygen in the steel, but Ca can modify part of the MgO·Al<sub>2</sub>O<sub>3 </sub>spinel inclusions during RH refining. In order to ensure the removal of 6–10 μm inclusions, the holding time is suitable for 19–42 min.
|
|---|
