Protective slag should have the ability to absorb the inclusions in the steel liquid, especially the inclusions in the crystallization at the curved moon surface. The protective slag should be assimilated on time. Otherwise, it will cause a large number of inclusions on the surface of the cast billet and under the skin.
At present to make the protection slag has the ability to absorb inclusions is not difficult, but difficult in the protection slag after absorbing a large number of inclusions, but also to maintain its good performance to meet the requirements of the continuous casting process, especially lubrication performance and uniform heat transfer performance.
Usually high inclusions in steel grades, such as those containing aluminum, titanium, and rare earth elements, the oxides of these elements into the slag, so that the performance of the protective slag has a large change, such as the alkalinity of the protective slag, melting temperature, and viscosity of a large change. When solving this type of steel, often choose a high alkaline high vitrification of the protection slag, received good results.