連続鋳造モールド内浸漬ノズル吐出口近傍におけるモールドパウダー巻き込みに関する水モデル実験

抄録

The problem of mold powder entrapment in molten steel in a continuous casting mold continues to be a serious obstacle to the producing of clean steel. Four types of the mechanisms of mold powder entrapment have been proposed on the basis of water model experiments. These mechanisms, however, cannot fully explain the size distribution of mold powder in the finished steel products. In this study, another type of entrapment mechanism was proposed. Namely, when the molten steel flow crosses the immersion nozzle, the pressure on the forward stagnation point increases, while that on the rear stagnation point decreases. As a result, the mold powder moves downwards along the rear surface of the immersion nozzle. If the mold powder reaches one of the ports of the immersion nozzle, it is sucked into the discharging molten steel flow, which causes significant mold powder entrapment. In order to ascertain the validity of this proposed mechanism, water model experiments were carried out using various kinds of silicone oils and salt water. The results of the model experiments revealed the possibility that the mold powder entrapment based on the mechanism proposed in this study takes place in the real continuous casting mold.