Numerical Investigation of Unsteady Molten Steel Flow and Inclusion Behavior in the Tundish in the Ladle Change Period

Abstract

Prevention of defects caused by inclusions is an important technical issue in the production of highgrade steel products. In particular, inclusion removal in the continuous casting tundish is an essential technology for production of high-grade steels. It is well known that inclusion removal in the ladle change period is more difficult than during steady state casting. However, the unsteady phenomena of molten steel flow and inclusion motion in the ladle change period have not been studied in detail. To clarify these phenomena, unsteady molten steel flow and inclusion particle motion in the tundish in the ladle change period were investigated by numerical approaches. First, a numerical simulation of the unsteady molten steel flow and unsteady inclusion particle motion was carried out. As a result, it is found that the outflow rate of inclusions to the mold increases sharply immediately after the start of pouring from the new ladle. Second, flow characterization of the molten steel flow in the tundish in the ladle change period was carried out. A new method using a combined model was proposed to evaluate the flow characteristics of unsteady state tundishes in the ladle change period. The method was applied to the numerical simulation results, and showed that sharp increases in the well-mixed volume and dead volume occur simultaneously with inclusion outflow. This result indicates that flow control at the start of pouring from a new ladle is an effective approach to improve the inclusion removal performance of tundishes.

Optimization of Steel Flow in the Tundish by Modifying its Working Area

“…Therefore, in order to conduct the research study on the flow fields and also on the parameters to set the mould oscillation rate, there are applied determined laboratory and mathematical models, which constitute the basis for numerical modelling. [1][2][3].…”

Numerical Simulation of Transient Multiphase Flow in a Five-Strand Bloom Tundish during Ladle Change

“…At present, most numerical investigations of the tundish have only considered the steady casting process using flow field modeling. Simulations of transient casting [6][7][8][9][10][11][12][13] are still only rarely undertaken. Takahashi et al [7] simulated the velocity field in slab tundish during the ladle change, and provided a basis for predicting the change of the floating condition of inclusions.…”

“Vacuum Shroud (VS)”-A Green Flow Control Device (FCD) towards Replacement of “Turbo Stop” In Tundish Metallurgy

“…Exogenous inclusions mainly generated due to re-oxidation in tundish, slag entrapment, lining erosions which have detrimental effect on cast structure and to control this adverse effect on product state of art technology is required to develop for future sustainability [41]. Numerical simulation was applied by some researchers to evaluate the inclusion characteristics during ladle change over period and it was found that during this unsteady state inclusion percentage in the tundish as well as mold increases and also it is inferred that proper flow control device can enhance the inclusion removal rate in tundish during opening of new ladle in a sequence casting operation as clean steel is highly desirable for particularly high grade steel casting [42]. So it is highly desirable to judge the inclusion removal efficiency of different types shroud and impact pad combinations.…”