In the production of IF (interstitial free) steel, Ti will react with oxygen in the molten steel and/or with Al_2O_3during the Ti alloying process. These reactions lead to the formation of Ti containing inclusions, whichinfluence Ti yield during alloying and also steel cleanliness. The formation of non-metallic inclusions such asAl_2O_3, TiO_x, and Al-Ti-O oxides might cause both nozzle clogging during continuous casting and loss of finalproduct quality.1) On the other hand, from the viewpoint of “oxide metallurgy”, Ti containing complex oxidescan be utilized as nuclei for MnS precipitation2), which can serve again as nucleation site for acicular ferriteafter welding or heat treatment, hence improving steel toughness and strength.3,4) It is, therefore, of greatconcern to study the Al_2O_3 and Al-Ti-O inclusion behaviours in the liquid steel.In the present work, in-situ observations using the high temperature confocal scanning laser microscope(CSLM) equipped with an infrared image furnace (IIF) were carried out on industrial samples containingdifferent types of inclusions, i.e. Al_2O_3 and AlTiO_x. After the CSLM tests, assessment of inclusion morphologyand composition was conducted with Environmental Scanning Electron Microscope (E-SEM) on the samplesurface and with Scanning Electron Microscope (SEM) after extraction of the inclusions from the steelsamples. The relevance of the inclusion behaviour with steel composition was elucidated on the basis ofchemical analysis of the samples before and after experiments.
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