Optimization of submerged entry nozzle parameters for ultra-high casting speed continuous casting mold of billet

Owing to the smaller cross-sectional size of the billet, the effect of the position of the submerged entry nozzle (SEN) on the fluid flow in a curved mold is more prominent. The transient fluid flow, heat transfer, and solidification behavior at different nozzle positions and mold electromagnetic stirring (M-EMS) are investigated using a 3D transient mathematical model. The symmetry index, S, is introduced to quantitatively evaluate the symmetry of the flow field. When the SEN is offset to the outer curve, S is the highest, the flow field mixing is the best, and the liquid level fluctuation is minimal. When the SEN is offset to the inner curve, S is the lowest, and the washing of the solidified shell on the inner curve side is more significant, causing the solidified shell thickness on the inner curve to be thinner, which can easily cause steel breakout accidents. The M-EMS can improve the uneven flow field caused by the nozzle position. In actual production, the SEN can be appropriately offset to the outer curve, and the application of M-EMS can improve the flow field distribution of molten steel.

Section: Model Validationsupporting

confidence: 81%

Section: Effect Of Nozzle Position On Heat Transfer and Solidificationmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Nozzle Position on Fluid Flow and Solidification in a Billet Curved Mould using Mould Electromagnetic Stirring

Wang

Qiu

Zhu

et al. 2023

“…[ 1 ] In recent years, continuous casting has become increasingly popular in the world as the most important means of modern steel production. [ 2 ] However, the problem of cracks in continuous casting slabs has been affecting the quality of steel products, which in turn restricts the efficiency of the metallurgical industry. The problem of transverse corner cracks at medium plate continuous casting slabs is more complex and also one of the frequently cracking problems puzzling metallurgists.…”

Section: Introductionmentioning

confidence: 99%

Research Mechanism of Formation on Transverse Corner Cracks in the Continuous Casting Slab of Peritectic Steel

Zhou

Yin

Liu³

et al. 2022

To figure out the formation mechanism of transverse corner cracks at the inner and outer arc of peritectic steel slab, the metallurgical microscope, scanning electron microscope with energy‐dispersive X‐ray spectroscopy, and electron probe‐X‐ray microanalysis, are used to study cracks. High‐temperature mechanical properties and the stress distribution of the outer arc of the bending section under different roll gap schemes are studied and simulated. The outer arc cracks expand along the grain boundary, while the inner arc cracks not only extend along the grain boundary but also traverse along the grains. The outer arc cracks are mainly generated at the bending section and are formed and expanded along the ferrite film. The inner arc cracks' cracking temperature is higher than the temperature of austenite transformation to ferrite. The third brittle temperature ranges are 650–850 °C, and the transverse corner crack sensitivity zone is 680–837 °C. The inner arc cracks are generated because of the element segregation and low temperature of the corner and then extended at the straightening section, and new cracks exist. The weakened cooling intensity and bending earlier at the bending section help to reduce the equivalent stress on the slab. The optimized experiments are conducted, and the transverse corner cracks are reduced significantly.

“…[6,7] Fortunately, the aforementioned negative effects can be reduced by suitable operating parameters and electromagnetic technologies to meet quality requirements. [2,3,[8][9][10] Because of these beneficial effects, AGI is used in the bloom mold of Hebei Iron & Steel Group Hansteel Company, [11] Angang Steel Company Limited, [12] Nanjing Iron and Steel Company Limited [13] to improve the castability of alloy steels that are prone to clogging. However, due to the small cross-sectional area of the bloom mold, surface defects from captured bubbles are more serious.…”

mentioning

confidence: 99%

Numerical Simulation for Two‐Phase Flow, Heat Transfer, and Inclusion Transport in Bloom Mold Considering the Effects of Argon Gas Injection and Mold Electromagnetic Stirring

Xuan

Chen

2022

During the continuous casting process, the fluid flow is a critical factor that affects the heat transfer and the inclusion transport, which, in turn, determines the final quality of steel products. Argon gas injection (AGI) is widely employed to prevent submerged entry nozzle (SEN) clogging in the slab mold. [1,2] After entering the mold, argon bubbles alter the flow pattern, promote inclusion floating, and improve the melting of mold flux. [1][2][3][4] However, a large amount of argon gas can lead to increased level fluctuations, uneven distribution of mold flux, and even slag entrainment. [1,3,5] Moreover, argon bubbles may be captured by the solidified shell and become surface defects. [6,7] Fortunately, the aforementioned negative effects can be reduced by suitable operating parameters and electromagnetic technologies to meet quality requirements. [2,3,[8][9][10] Because of these beneficial effects, AGI is used in the bloom mold of Hebei Iron & Steel Group Hansteel Company, [11] Angang Steel Company Limited, [12] Nanjing Iron and Steel Company Limited [13] to improve the castability of alloy steels that are prone to clogging. However, due to the small cross-sectional area of the bloom mold, surface defects from captured bubbles are more serious. [12] As a widely used electromagnetic technology, mold electromagnetic stirring (M-EMS) can enhance molten steel flow, [14] promote superheat dissipation, [15] and improve the equiaxed crystals ratio, [16] more importantly, it can reduce bubbles captured by the solidified shell in the slab mold [17][18][19] and the bloom mold. [12] Despite these advantages of M-EMS, the double action of M-EMS and AGI may cause more level fluctuations, which has been reported in the slab mold [20] but not in the bloom mold. Therefore, to provide theoretical guidance for quality improvement and AGI application, it is essential to investigate the effects of AGI and M-EMS on fluid flow, temperature distribution, and inclusion removal in the bloom mold.Many experimental researches have been performed to investigate the two-phase flow of molten steel and argon gas in the SEN and mold regions using water models [21][22][23][24][25] and liquid metal models. [26][27][28][29] In the water model, it is easy to capture the twophase flow but difficult to consider the effect of the magnetic field because of the low electrical conductivity of water. Although the liquid metal model can apply the magnetic field, the two-phase flow in the mold is hard to visualize. Thus, numerical simulation is widely used to investigate the two-phase flow in the mold. Several studies investigated the effect of AGI on the flow field, [3,7,[30][31][32][33] temperature distribution, [3,30] initial solidification, [3] inclusion removal, [7,31,33] and slag-steel interfacial behavior, [1,4,5,32]