Effect of Al–Ti Concentration on the Alumina Inclusions Agglomeration Behavior on the Surface of Molten Steel

As we all know, the alumina inclusions on the surface of aluminum-killed molten steel are quickly attracted to form large clusters, but the alumina-magnesia complex inclusions disperse, where the interface characteristics between inclusions and molten steel play a crucial role in the agglomeration behavior on the surface of molten steel. In the present work, the effect of titanium and aluminum concentrations on the interface characteristics between molten steel and alumina inclusions is studied by using an improved sessile drop method. Then, the agglomeration behavior of alumina inclusions on the surface of molten steel is investigated by using a high-temperature laser microscope, and the attractive forces are discussed in detail from both the capillary force and viscous drag forces based on the interface characteristics between the inclusion and molten steel. The results show that the in situ observed attractive forces between the alumina inclusions on the surface of the molten steel are from 9.69 × 10−21 to 3.54 × 10−15 N, which reduce and increase, respectively, with the increase of titanium and aluminum concentration. It is agreeable to the calculated attractive force combining interface characteristics between inclusions and molten steel based on the concept of capillary force, which ranges from 1.94 × 10−21 to 3.76 × 10−16 N. Additionally, the attractive force decreases due to the viscous drag forces, which are approximately 2.43 × 10−21 to 3.11 × 10−18 N as the inclusion particles are close to each other.