Formation and Evolution of Non-Metallic Inclusions during Deoxidation by Al Addition in BOF Crude Steel

In order to know the types of inclusions in BOF crude steel and their evolution during Al deoxidation, steel samples are taken from industry and deoxidation with aluminum experiments are carried out in laboratory. The results show that the BOF crude steel is an important source of inclusions. A lot of (Fe, Mn)O inclusions and some BOF slag droplets (mainly calcium silicates) were found in BOF crude steel. During Al deoxidation, alumina clusters could be formed because of homogeneous nucleation, while some singular alumina particles can also be generated on (Fe, Mn) O inclusions due to heterogeneous nucleation. Besides, (Fe, Mn) O would be reduced by dissolved Al into alumina completely. The unstable oxides in calcium silicates will be reduced by dissolved Al in liquid steel to form calcium aluminates. The study results are very helpful to understand the origin and evolution of different types of inclusions in industry.