Bubble Formation into Flowing Liquid Through a Refractory Having Bad Wettability and Inclusion Removal in Tundish by Ar Bubbles

Abstract

The injection method of Ar gas into the molten steel through porous plug is usually applied to the removing process of the nonmetallic inclusions. It is commonly confirmed by many studies on this method that the availability of the injected Ar gas increases with the decreasing bubble diameter. In this paper, the influence of the pore diameter, flow rate of Ar gas, the wettability between liquid and porous plug and the streaming velocity of liquid on the bubble diameter is experimentally examined and the obtained results are analytically discussed. When Ar gas is injected into the stationary liquid through the wettable porous plug the bubble diameter increases with the increasing pore diameter and flow rate of Ar gas. In case of the wettability is bad the bubble diameter grows up greater and shows almost constant value regardless of the injection conditions. To make this grown bubble fine it is effective to give a stream to the liquid. The experimental results were applied to the manufacturing equipment aiming to make the molten steel clean in tundish. This test showed that the Ar gas bubble by the streaming molten steel has a removing ability of the nonmetallic inclusions in molten steel.