Comparison of the Flow Field in a Slab Continuous Casting Mold between the Thicknesses of 180 mm and 250 mm by High Temperature Quantitative Measurement and Numerical Simulation

In the present work, the flow field in a slab continuous casting mold with thicknesses of 180 and 250 mm are compared using high temperature quantitative measurement and numerical simulation. The results of the numerical simulation are in agreement with those of the high temperature quantitative measurement, which verifies the accuracy and reliability of the numerical simulation. Under the same working conditions, the velocities near the mold surface with the thickness of 180 mm were slightly higher than those of the mold with the thickness of 250 mm. The flow pattern in the 180 mm thick mold maintains DRF more easily than that in 250 mm thick mold. The kinetic energy of the jet dissipates faster in the 250 mm thick mold than in the 180 mm mold. For double-roll flow (DRF), as the argon gas bubbles can be flushed into the deeper region under the influence of strong jets on both sides, the argon bubbles distribute widely in the mold. For single-roll flow (SRF), as the argon bubbles float up quickly after leaving the side holes, the bubble distribution is more concentrated in the width direction, which may cause violent interface fluctuation and slag entrainment. The fluctuation at the steel-slag interface in the mold with 180 mm thickness is greater than that in the mold with 250 mm thickness but less than 5 mm. The increase of mold thickness may lead to a decrease of the symmetry of the flow field in the thickness direction and uniformity of mold powder layer thickness. In summary, the steel throughput should be increased in the 250 mm thick mold compared with that in the 180 mm thick mold.

A Simulation Method for the Optimization of Cooling Water Slot Structure in Slab Continuous Casting Mold Combined With SEN

The temperature field in the full 3D finite element mold model combined with submerged entry nozzle(SEN)(Full SEN-3D FEMM) is simulated with Fluent of ANSYS 18.0 Package to apply the maximum heat flux density on the heat face of mold copper plate obtained through this simulation to the element model of the copper plate, and thermal stress and strain simulations on the copper plate and stainless back ones are conducted with Workbench of ANSYS 18.0 Package to confirm the reasonable designing factors for the water slot structure on the copper plate. The maximum heat flux densities on the wide and narrow heat faces of the copper plates are given on the initial shock areas of molten steel flux injected through SEN. With constant heat flux density on the heat face, the more the thickness of copper plate increases, the more the max- and min temperatures increase and the difference between them decreases. Elastic and plastic deformations on the copper plate are made during continuous casting(CC) process; the former occurs around the water slots and the latter around the heat face with the highest temperature, which regards 20-18-17 as the most reasonable one among 4 plans for the water slot structure.

On Modelling Parasitic Solidification Due to Heat Loss at Submerged Entry Nozzle Region of Continuous Casting Mold

Continuous casting (CC) is one of the most important processes of steel production; it features a high production rate and close to the net shape. The quality improvement of final CC products is an important goal of scientific research. One of the defining issues of this goal is the stability of the casting process. The clogging of submerged entry nozzles (SENs) typically results in asymmetric mold flow, uneven solidification, meniscus fluctuations, and possible slag entrapment. Analyses of retained SENs have evidenced the solidification of entrapped melt inside clog material. The experimental study of these phenomena has significant difficulties that make numerical simulation a perfect investigation tool. In the present study, verified 2D simulations were performed with an advanced multi-material model based on a newly presented single mesh approach for the liquid and solid regions. Implemented as an in-house code using the OpenFOAM finite volume method libraries, it aggregated the liquid melt flow, solidification of the steel, and heat transfer through the refractory SENs, copper mold plates, and the slag layer, including its convection. The introduced novel technique dynamically couples the momentum at the steel/slag interface without complex multi-phase interface tracking. The following scenarios were studied: (i) SEN with proper fiber insulation, (ii) partial damage of SEN insulation, and (iii) complete damage of SEN insulation. A uniform 12 mm clog layer with 45% entrapped liquid steel was additionally considered. The simulations showed that parasitic solidification occurred inside an SEN bore with partially or completely absent insulation. SEN clogging was found to promote the solidification of the entrapped melt; without SEN insulation, it could overgrow the clogged region. The jet flow was shown to be accelerated due to the combined effect of the clogging and parasitic solidification; simultaneously, the superheat transport was impaired inside the mold cavity.