Observation of Initial Interfacial Reaction between High Aluminum Molten Steel and CaO–Al2O3 Inclusion at 1873 K Using Laser Confocal Scanning Microscopy and Micro‐Computerized Tomography

A new method is proposed to investigate the transient reaction between the CaO–Al2O3 inclusion from slag entrainment and the high aluminum molten steel. The confocal laser scanning microscopy, the X‐ray computerized tomography technology, and the scanning electron microscope‐energy dispersive spectrometer are combined to observe the variation of the size, shape, and composition of the entrained slag inclusion with time. The CaO in the inclusion is reduced by the dissolved aluminum in the molten steel. With the increase of the dissolved aluminum content from 0.02 to 5.73 wt%, the CaO in inclusions under equilibrium state decreased from 55 to 35 wt%. The reaction between the dissolved aluminum in the steel and the CaO in the calcium aluminate inclusion at 1873 K is discussed through thermodynamic and kinetic calculations, which are consistent with experimental results. It is indicated that the mass transfer coefficient of the CaO in the inclusion is 2.95 × 10−5 m s−1.