© 2013 ISIJ 792 ISIJ International, Vol. 53 (2013), No. 5, pp. 792–801 Turbulent Flow Phenomena and Ce 2 O 3 Behavior during a Steel Teeming Process Peiyuan NI, 1) Lage Tord Ingemar JONSSON, 1,2) Mikael ERSSON 1) and Pär Göran JÖNSSON 1) * 1) KTH-Royal Institute of Technology, Division of Applied Process Metallurgy, Department of Material Science and Engineering, SE-100 44 Stockholm, Sweden. 2) FOI, Swedish Defence Research Agency, Division of CBRN Defence and Security, SE-901 82 Umeå, Sweden. (Received on January 14, 2013; accepted on February 14, 2013) Steel flow phenomena and Ce2O3 inclusion behavior are presented in this paper. A three-dimensional model was developed to describe the steel flow phenomena and the inclusion behavior during a teeming process. The Kim-Chen modified k-ε turbulent model was used to simulate the turbulence properties and the Height-of-Liquid model was used to capture the interface between gas and steel. A Lagrangian method was then used to track the inclusions and to compare the behaviors of different-size inclusions in the steel flow. In addition, a statistical analysis was carried out by the use of a stochastic turbulence model to investigate the behaviors of different-size inclusions at different nozzle regions. The results show that the steel flow was the most turbulent at the connection region of the straight pipe part and the expanding part of the nozzle. All inclusions with a diameter smaller than 20 μ m were found to have a sim- ilar trajectory and velocity distribution in the nozzle. However, inertia force and buoyancy force were found to play an important role for the behaviors of large-size inclusions/clusters. The statistical analysis results indicate that the regions close to the connection region between different angled nozzle parts seem to be very sensitive with respect to deposition of inclusions. KEY WORDS: steel flow; ladle teeming; numerical simulation; inclusion behavior; CFD; clogging; deposition. 1. Introduction Inclusions in molten steel have received worldwide con- cern due to their serious influence on both the steel product quality and the steel production process. These inclusions may come from the deoxidation process, reoxidation by air and/or slag during steel transfer, slag at the top surface of steel, refractory of the steel containing vessel, dust of scrap, and so on. The influence of inclusions on a continuous cast- ing process is quite serious. They can break up a casting pro- cess by clogging a tundish nozzle when they deposit onto the wall. Overall, this nozzle clogging has been a problem for the steel continuous casting process, especially for Al- killed steel, Ca-treated steel, Rare Earth Metal treated stain- less steel and Ti-killed steel. The reasons for the clogging and the possible countermeasures to prevent clogging have been extensively studied. 1–8) Some research has been carried out to remove inclusions in molten steel during a ladle treat- ment as well as during a tundish operation. 9–12) However, it is impossible to obtain a completely clean steel with the cur- rent steel production technology. Clogging is closely related to the inclusion behavior in steel. Therefore, the knowledge on the steel flow and the inclusion behavior is rather impor- tant for an understanding of the nozzle clogging process and for making a prediction on clogging situations. Computer simulation has become an effective and inex- pensive method to study the steel flow and inclusion behav- ior. Both of them are difficult to be measured or seen direct- ly in production. A great amount of mathematical simulations, as is shown in Table 1, 13–35) have propelled our understanding of both the steel flow and inclusion behavior. As early as 1973, Szekely et al. 13) modeled fluid flow in a mold with a straight nozzle and a bifurcated nozzle, respec- tively. In addition, Thomas and Bai et al. 15–23) carried out systematic research on steel flows in nozzles. The effects of nozzle parameters and operating practice on the steel flow characteristics in a SEN were studied. Furthermore, steel flows in nozzles were also studied and compared by using of different turbulence models. 30–35) Some researchers also studied the inclusion behavior in a nozzle during casting. Wilson et al. 14) investigated the steel flow characteristics in a nozzle and tracked the trajectories of inclusions. The depo- sition of inclusions due to a centripetal force and turbulence was also studied. Yuan et al. 24) predicted the fraction of inclusions with different densities and sizes entrapped by a lining in a stopper-rod nozzle. Zhang et al. 25–27) tracked the trajectories and entrapment locations of inclusions in a slide- gate nozzle. Long et al. 35) studied the Al 2 O 3 inclusion behav- ior in a turbulent pipe flow. Effects of factors, such as release location of inclusion, inclusion size, pipe diameter, casting speed, on the entrapment probability were investigated. Previous modeling studies, in Table 1, mainly focused on the steel flow characteristics in a nozzle. Behaviors of dif- ferent kinds of inclusions with different sizes released from different locations of a nozzle are not fully understood. In this paper, the Ce2O3 behavior and steel flow phenomena in a gradually expanding nozzle during a teeming process were studied. Ce2O3 is formed during Rare Earth Metal (REM)- alloyed stainless steel production. Ce2O3 is difficult to * Corresponding author: E-mail: parj@kth.se DOI: http://dx.doi.org/10.2355/isijinternational.53.792