The molten steel flow in the continuous casting mold and entrapment of inclusions and bubbles on the inner surface of the solidified shell are examined to clarify the origin of internal defects in steel products. Defects on steel sheets are caused by inclusions and bubbles entrapped on the solidified shell during casting. It was found that bubbles are able to penetrate deeply due to an unbalanced time-dependent flow. This phenomenon can be explained by the Large Eddy Simulation model, which is capable of simulating the time-dependent flow.
The number of inclusions increases as the bubble diameter and the distance of the position of entrapment from the top free surface increase. This indicates that bubbles collect inclusions while traveling in the molten steel in the continuous caster. A simple mathematical model is presented to explain how the inclusions are collected by bubbles.
The calculation results also reveal that the static magnetic field generated by the FC Mold reduces time-dependent flow changes and thereby prevents internal defects caused by bubbles and inclusions.