Evolution of Al-Ti Complex Oxide Inclusions in Interstitial-Free Steel Analyzed Using CALPHAD, SEM, EDS, EBSD, and CSLM
摘要
The very low C content in interstitial-free (IF) steel is achieved through vacuum degassing and by adding Ti to Al-deoxidized molten steel during the steelmaking process. However, this low C content can lead to reoxidation, which, in turn, generates various oxide inclusions. Despite its significance, a comprehensive understanding of the evolution of these oxide inclusions has been hindered by the scarcity of fundamental information, such as phase equilibria in the relevant system. In this study, the thermodynamics and phase equilibria of the Fe-Al-Ti-O system, along with the evolution of oxide inclusions in the molten steel, were analyzed using various analytical techniques: CALculation of PHAse Diagrams (CALPHAD), scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, and confocal scanning laser microscopy. High-temperature monitoring of oxide inclusion evolution through in-situ CSLM, SEM, and EBSD revealed that the primary constituents of the major oxide inclusions were alumina (corundum). Notably,