Two-phase flow numerical simulation of molten steel and argon gas in a continuous casting mold

For steel continuous castings, it is essential to control the molten steel velocity at the meniscus, since the velocity is closely related to surface defects on the resultant products. Argon gas is supplied with molten steel into the mold through a submerged entry nozzle to prevent clogging. In this study, to investigate the influence of argon gas on molten steel flow, a numerical simulation was carried out for several casting speeds. The simulation result of a higher casting speed is similar to a casting case in which argon gas is not used. The simulation result of a lower casting speed indicates that as argon gas bubbles ascend near the nozzle, they induce the molten steel to flow with them. The surface velocity magnitude of a lower casting speed is reduced more due to the dispersion by argon gas floatation. In consequence, meniscus molten steel flows from the nozzle to the narrow face of the mold. This flow direction is opposite to a higher casting speed case. By balancing the molten steel throughput and the argon gas flow rate, molten steel flow patterns can be controlled. We can conclude that the argon gas flow ratio is an important element to control the product quality.