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The effects of rare‐earth treatment on cleanliness, corrosion resistance, microstructure, and mechanical properties of 75Cr1 steel are investigated by industrial trial. In the results, it is shown that the appropriate La–Ce addition can effectively remove oxygen and sulfur elements in steel, and total oxygen (T.O) and S contents decrease by 45% and 33%, respectively. After La–Ce treatment, the typical inclusions in steel are transformed from (Mg–Al–O)–CaS composite inclusions to RExSy–CaS inclusion with a small amount of Al2O3. The number and average size of inclusions in steel are significantly reduced, and the morphology of inclusions changes from irregular shape to spherical shape, which contributes to the improvement of the corrosion resistance of 75Cr1 steel. Furthermore, the pearlite spacing and the grain size are refined, the tensile and yield strengths are significantly enhanced in the test of La–Ce‐treated steel. The 75Cr1 steels are fabricated in small batches, which avoids the nozzle clogging resulted by rare‐earth treatment during continuous casting. It implies that rare‐earth treatment to improve the quality of 75Cr1 steel shows the strong industrial applicability. [ABSTRACT FROM AUTHOR]

The clogging of the submerged entry nozzle (SEN), as an important device to connect the tundish and the mold, has been widely concerned. However, until now, the clogging of the SEN cannot be eliminated during the casting. Herein, the clogging behavior of the SEN during the casting of ultralow‐carbon steel is studied using an external DC electric field. The findings demonstrate that the DC electric field inhibits the growth of the clogging on the outlet and the thickness of the clogging layer is small, which ensures the integrity of the profile of the outlet. After DC treatment, the interface of the clogging is clear and the density is increased, which reduces the pollution to molten steel. At the same time, the fluctuation of the mold level is significantly improved, and the defect rate of cold rolling is effectively reduced to 30% of the original level, which is beneficial to the overall performance of the slab. [ABSTRACT FROM AUTHOR]

Wettability of mold flux on stainless steel is a very important index to reflect the possibility of slag entrapment during the continuous casting process. In this study, the wetting behavior of mold flux droplet with different size on stainless steel is investigated using sessile drop method. Results show that the contact angle at 1573 K increases from 64.62 ± 0.25°, 62.56 ± 0.2° to 61.46 ± 0.2° and 60.56 ± 0.2°, with the size of the original flux sample increasing from 3, 4 to 5 and 6 mm. No chemical reaction occurs at the interface between mold flux and steel substrate via the thermodynamic calculation and microstructure analyses. Furthermore, the line tension of flux droplet/stainless steel/Ar‐5%H2 system ranges from 160.55 to 125.19 mN m−1 at the temperature range of 1473–1573 K. It is due to the positive line tension (line energy) which decreases the wettability of flux droplet on steel substrate and results in an increase of contact angle when the droplet size reduces. [ABSTRACT FROM AUTHOR]

The numerical simulation is combined with high‐temperature measurement to study the effects of electromagnetic braking (EMBr) and casting speed on the flow field, the fluctuation of the interface of the steel and slag, the distribution of argon gas bubbles, and the removal ratios of inclusions in the mold with a size of 1050 × 230 mm. The numerical simulation results and the high‐temperature measurement results of the velocities of molten steel at the 1/4 width and center of the thickness near the mold surface are in good agreement. The EMBr can reduce the velocity near the mold surface, the fluctuation of the interface between steel and slag, and the number of argon gas bubbles near narrow walls and decrease the total removal ratio of inclusions from 27.29 to 23.24%. When the casting speed is increased from 1.6 to 2.0 m min−1 with EMBr, the velocity of molten steel near the mold surface is increased. Even under the condition of a high casting speed of 2.0 m s−1, the velocity of molten steel near the surface is still in a reasonable range with EMBr. The total removal ratio of inclusions increases from 20.76 to 23.90%. [ABSTRACT FROM AUTHOR]

To get rid of the restrictions imposed by the components of the original mold flux and minimize fluorides to the largest extent, this article has designed the continuous casting mold flux for high‐aluminum steel with an aluminum content of 1.35% and tested the performance manifestations of the mold flux by integrating equipment like a rotational viscometer, S/DHTT‐TA‐III thermal analyzer, and X‐ray diffraction. The composition of the continuous casting mold flux for high‐aluminum steel is: CaO = 23–43 wt%, SiO2 = 12–25 wt%, Al2O3 = 14–26 wt%, B2O3 = 13–17 wt%, and Li2O = 4–8 wt%. The newly designed mold flux has a lower melting temperature and its performance still satisfies the conditions for continuous casting after the reaction. The crystallization process of the on‐site using mold flux lasts 198 s, with the precipitated phases being Na2CaSiO4 and Ca3Si2O7. The crystallization process of the newly designed mold flux lasts ≈324 s, with the precipitated phase mainly being LiAlO2, and the mold flux can maintain a low viscosity and a relatively thick liquid slag layer for a longer period of time. [ABSTRACT FROM AUTHOR]

Pulsed magneto‐oscillation (PMO) has a high homogenization effect on continuous castings, but the heritability of it on hot‐rolled wire rods has not been studied. Recently, the effect of pulsed magneto‐oscillation on SCM435 cold heading steel billet and its hot‐rolled wire rod were investigated. A 180 mm × 180 mm ten‐strand continuous casting machine was used, with the first strand treated by pulsed magneto‐oscillation, and billets hot‐rolled to Φ6.5 mm wire rods. The results showed that compared with the billet without pulsed magneto‐oscillation treatment, the proportion of central equiaxed grain zone of pulsed magneto‐oscillation treated billet increased from 26.5% to 37.4%, and the secondary dendritic arm spacing of columnar was reduced. Futhermore, the segregation index ranges of Cr and Mn decreased by 47.1% and 33.3%, respectively. For the hot rolled wire rods, the solutes homogeneity and the mechanical properties of the rods produced by pulsed magneto‐oscillation treated billet were improved. And its banded structure was significantly refined, where the maximum band width was reduced from 35.4 μm to 12.3 μm. This study showed that the properties of wire rod could be significantly improved by improving the homogeneity of the casting billet by pulsed magneto‐oscillation, and a good histogenetic effect was obtained. [ABSTRACT FROM AUTHOR]

As representative compositions of the mold flux used in the continuous casting of steel, the temperature and composition dependence of the thermal conductivity of alkali silicate glasses and melts was investigated in the range of 300–1700 K using molecular dynamics (MD) simulations. MD simulations can exclude disturbances such as radiation, convection, and impurities, and extract only the effect of phonons on the thermal conduction. Thermal conductivity determined by the laser flash (LF) method was reported to be three times higher than that obtained by the unsteady hot wire (HW) method in the high‐temperature range of 1250–1550 K for 33.3Na2O–66.7SiO2 (mol%). This study shows that (1) the thermal conductivity estimated by MD simulations was closer to the experimental value of the LF method than those of the HW method above 1200 K, which suggests that the LF method is reliable and that the effect of radiation on the thermal conductivity is not significant. (2) The decrease in the thermal conductivity measured by the LF method in the range of 1250–1550 K was attributed to the decrease in the bulk modulus of the 33.3Na2O–66.7SiO2 melt. (3) In a series of Na2O–SiO2 melts, the sound velocity calculated by MD decreased with increasing Na2O content, which is consistent with Shiraishi's ultrasonic wave measurements. [ABSTRACT FROM AUTHOR]

To clarify the formation mechanism of clogging on submerged entry nozzle of Q355 steel, scanning electron microscope‐energy dispersive spectrometer (SEM‐EDS), cathodoluminescence and FactSage7.1 thermodynamic software are used to study the morphology and stratified structure of Q355 steel nozzle. The results show that, clogging on Q355 steel can be divided into decarburized layer, ≈1.5 mm, dense accumulation layer, about 2 mm, and loose accumulation layer, ≈1.5 mm. The phenomenon of CaO·2Al2O3, CaO, Ti2O3, Al2O3, and 2CaO·Ti2O3 inclusions precipitated from the molten steel and deposited in the inner wall of the nozzle during continuous casting is analyzed. The formation mechanism of the clogging is explained by drawing the clogging process diagram and thermodynamic calculation. The range of total Ca content in molten steel which should be controlled between 0.0012% and 0.0016% to reduce clogging at the nozzle is given. [ABSTRACT FROM AUTHOR]

The effect of sulfur content on sulfide inclusion and dendrite MnS in continuous casted 20CrMnTi gear steel is investigated. There are two main types of sulfides in 20CrMnTi steel: pure MnS and TiN–MnS composite inclusions. The number of TiN–MnS is higher than MnS, especially in the edge of the billet. TiN–MnS is smaller both in area and size than pure MnS. The statistical results of dendrite MnS show that the increase of S content decreases the average size of sulfides, whereas raises the number and the maximum size of sulfides. With the S content increasing, the proportion of large‐sized dendrite MnS in steel decreases, but the amount of large‐sized dendrite MnS increases, which results in the increase of number of large‐sized dendrite MnS. The average area of dendrite MnS inclusions first increased and then decreased from the edge to the center of billet, and the maximum area appeared at about 1/2 radius of the billet. Comparison with the microstructure of the two billets, the proportion of ferrite increased with the increase of S content. [ABSTRACT FROM AUTHOR]

The characteristics, formation mechanism, and removal of large‐sized CaO–Al2O3–SiO2 inclusions in D2 high‐speed railway wheel steel are investigated. Large‐sized CaO–Al2O3–SiO2 inclusions are present in the continuous casting billet, with SiO2 and CaO content ranging from 5 to 15 and 30 to 65 wt%, respectively. The size mainly exceeds 10 μm. These inclusions originate from the calcium‐treatment stage of the refining process, during which liquid CaO–Al2O3–SiO2 inclusions are formed in the liquid steel. The contact angle between these inclusions and the liquid steel is below 40°, which results in excellent wettability. Consequently, the inclusions are difficult to remove from the liquid steel and are thus inherited into the billet. By reducing the SiO2 content and controlling CaO content between 8 and 30 wt%, small‐sized inclusions are formed. This requires reasonable control of the Al and Ca content in the liquid steel. When the Al and Ca content in liquid steel is maintained at 0.012 wt% and 8 ppm, respectively, the inclusions in the billet are mainly CaO·6Al2O3 (CA6) and CaO·2Al2O3 (CA2), both under 5 μm in size. These inclusions represent the suitable inclusions in steel. [ABSTRACT FROM AUTHOR]

CaO‐Al2O3‐B2O3‐based slag is among the most promising “nonreactive” mold fluxes for continuous casting of high‐aluminum steel. However, CaO‐Al2O3‐B2O3‐based slag system exhibits a stronger crystallization ability compared to traditional mold fluxes. Herein, calcium oxide in CaO‐Al2O3‐10%B2O3 slag is partially replaced by the same mass of barium oxide (5 and 10 mass%) to adjust the crystallization ability. The crystallization of glassy slags is then investigated using a differential scanning calorimeter and their crystallization kinetics are analyzed using the Matusita–Sakka model. The structural evolution of glassy slags from room temperature to 1200 °C is also investigated using in situ Raman spectroscopy. The kinetic analysis shows that the crystallization process of CaO‐Al2O3‐B2O3‐BaO glassy slags follows the surface crystallization mechanism. The predominant crystalline products are calcium monoaluminate (CaAl2O4) and calcium borate (Ca3(BO3)2). The partial replacement of calcium oxide by barium oxide inhibits the growth of CaAl2O4 in the slag by increasing the activation energy of crystal growth. The high‐temperature Raman spectroscopy study shows that the band between 700 and 900 cm−1 gets weaker relative to the band between 450 and 650 cm−1 at high temperatures. This indicates the strengthening of bending vibration of Al‐O‐Al, which is consistent with the precipitation of CaAl2O4 with full oxygen bridging. [ABSTRACT FROM AUTHOR]

For the special casting environment of large round bloom mold with four‐hole nozzle, the reasonable choice of mold electromagnetic stirring (M‐EMS) location is of great significance to the quality control of bloom. In this study, the four‐hole nozzle arc continuous casting of φ600 mm‐large round bloom is taken as an example, a 3D mathematical model of liquid steel flow is built, and the solidification and heat transfer under M‐EMS is established. The optimum M‐EMS position was obtained as Z = 600 mm, which is enhanced flow rates, shell uniformity, and brittle interval width, and offers valuable insights for improving casting quality. [ABSTRACT FROM AUTHOR]

Flat nozzles are widely used in the continuous casting process due to their stable spraying effect, wide spraying area, and strong applicability. The type and arrangement of nozzles have a direct effect on cooling efficiency and blank quality. Herein, the spray characteristics of flat nozzles in slab continuous casting are investigated with a detecting apparatus developed by University of Science and Technology Beijing and Jiangsu Boji Company (named USTB‐BOJI DA), and a prediction model for water flux distribution under different flat nozzle arrangements is established. The results show that the nozzles in a foot roller zone have good spray performance and water flow distribution, while the nozzles in bending zones are poor. Comparing the predicted and measured results of water flux distributions, the average error is less than 0.24%, indicating that the predictive model is reliable. In addition, the evaluation index is defined for water flux distribution under multinozzle arrangement, and the solution equations are given by applying the predictive model. Combining the above research, a new design and optimization strategy/method for flat nozzle arrangements is proposed, which can significantly improve the uniformity of the water flux distribution of the spray in the secondary cooling zones during continuous casting. [ABSTRACT FROM AUTHOR]

During continuous casting process of high‐Mn high‐Al steel, soluble Al in the steel typically reacts with SiO2 in the mold flux, resulting in a decrease in SiO2 content and an increase in Al2O3 contents in the flux. The structure of slags with varying CaO/SiO2 and Al2O3/SiO2 mass ratio is investigated using Raman spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. In the deconvolution results of Raman and NMR spectra, it is shown that the relative fractions of QSi0$Q_{\text{Si}}^{0}$ and QSi1$Q_{\text{Si}}^{1}$ significantly increase, while QSi2$Q_{\text{Si}}^{2}$ and QSi3$Q_{\text{Si}}^{3}$ gradually decrease with an increase in the CaO/SiO2 mass ratio from 0.52 to 1.02, resulting in depolymerization of the bridge oxygen structure. The silicon–oxygen tetrahedron transforms into aluminum–oxygen tetrahedron when the Al2O3/SiO2 mass ratio increased from 0.05 to 1.01. The viscosity of the slags with varying composition from 1573 to 1373 K is investigated. In the results, it is shown that with an increase in the CaO/SiO2 mass ratio, the viscosity decreases, and the complex SiO network structure is depolymerized. The viscosity decreases first as the Al2O3/SiO2 mass ratio increases from 0.05 to 0.24 and then increases as the mass ratio from 0.24 to 1.01, with the network formers transfer from SiO to SiAlO structures. [ABSTRACT FROM AUTHOR]

Grade transitions in continuous casting can significantly improve casting machine productivity and reduce production costs. Accurate prediction of the mixing zone length is essential. A two‐dimensional transient model for grade transition in continuous casting is developed by integrating fluid flow, thermosolute transfer, and solidification. The model predicts the mixing zone changes at various casting speeds. The results indicate that positive segregation of the old steel (Q355NE) occurred at the billet's center, while the maximum negative segregation appears in the billet shell region. The process involves pausing the solidification of the grade transition connectors and the billet shell before casting is resumed with the introduction of a new steel (42CrMo). The extent of the mixing zone is determined by the carbon concentration at the centerline and 1/2 R. Numerical simulations of the temperature field and solute distribution trends are closely aligned with experimental data, validating the accuracy of the solute transport model. Although excessively slow speeds may disrupt the straightening process, reducing the casting speed and decreasing the mixing zone size. This study result provides theoretical guidance for the grade transition in large section round billet continuous casting. [ABSTRACT FROM AUTHOR]

The deposition and accumulation of inclusions is the dominant mechanism in nozzle clogging of the submerged entry nozzle. Previous modeling attempts of inclusion deposition have assumed that any contact between the inclusion and nozzle wall results in adhesion. Herein, an Eulerian–Lagrangian simulation with a stochastic adhesion model is used to study the effects of different inclusion‐wall sticking probability (Swall) on inclusion deposition. The results indicate that inclusion deposition is affected by both melt height and Swall. Lower melt heights result in increased deposition deeper into the nozzle and greater maximum particle area number density. The effect of Swall on the global deposition ratio can be divided into two regimes. When Swall increases from 0–0.05, there is a rapid rise in the global deposition ratio. When Swall > 0.05, the global deposition ratio increases only modestly with Swall. Changes to Swall also affect the location of deposition. When Swall decreases, the high and mid cases show greater relative deposition in the cone and taper sections of the nozzle, while the low melt height case shows greater relative deposition in the straight section of the nozzle. [ABSTRACT FROM AUTHOR]

Flow efficiency in a two‐strand continuous casting tundish is studied by analyzing the residential time distribution (RTD) curves in a small‐scale tundish water model using a conductive NaCl solution tracer. The velocity fields in the tundish water model are measured by particle image velocimetry, which is used to validate the results of the mathematical model in the article. It is found that the tracer concentration has a significant impact on the predicted dead volume fraction in the RTD analysis. Validated mathematical modeling of the computational fluid dynamics (CFD) technology is performed to explore the root cause of the defective results in the RTD analysis. It is found that the flow inside the tundish is sensitive to density variations caused by the injected tracer. A denser tracer will stay lower in the tundish by gravity and flow out of the tundish more quickly. A proper tracer concentration in the water model experiments is discussed to visualize the dead volume and improve tundish furniture design efficiently for future work, a new method using CFD modeling is proposed in this article, which can directly demonstrate the dead volume's location. [ABSTRACT FROM AUTHOR]

Computational models are powerful tools to quantify physical phenomena to gain valuable insights into a manufacturing process. Their accuracy is hindered, however, by uncertainty in the input data. Furthermore, when calibrating models with plant measurements, it helps to understand which variables have greatest effect on the critical model outputs. This work applies uncertainty quantification and sensitivity analysis to determine the most influential input parameters in the CON1D model of heat transfer and solidification in steel continuous casting with slag. Results show that the slag rim greatly affects heat flux near the meniscus, so control of its size is important. Heat flux and temperature down the mold depend greatly on velocity of the solid slag layer, and slag solidification temperature, which control the slag layer thickness, which in turn affects the interfacial resistance that controls heat transfer in the process. Scale formation on the mold coldface greatly increases mold temperatures. Based on the results presented here, models of heat transfer in continuous casting such as CON1D would benefit from plant measurements such as slag rim size and solid slag velocity, and lab measurements such as slag viscosity at lower temperatures, to better characterize this important slag property. [ABSTRACT FROM AUTHOR]

This review article reports the critical issue of reoxidation in clean steel production during secondary refining and continuous casting processes. Reoxidation presents substantial challenges to process stability and final product quality. Various sources of reoxidation, including exposure to oxidizing gases, reducible oxides in slag and refractories, and the presence of ferroalloys are explored. Fundamental reactions and their consequences, such as changes in steel composition, inclusion composition/morphology, and the formation of reaction products at the interface between liquid steel and refractory materials, are reviewed. High oxygen partial pressure on the refractory side is identified as a significant factor, particularly in tundish and continuous casting processes. To address reoxidation effectively, the review discusses modeling approaches like computational fluid dynamics and thermodynamic/kinetic modeling. In the industrial context, reoxidation in the tundish is mainly attributed to open‐eye formation in the tundish flux and reducible oxides like SiO2 in an insulating cover powder, for example, rice hust ash. Maintaining precise tundish flux control is crucial for steel cleanliness. In conclusion, this review highlights the multifaceted nature of reoxidation challenges in clean steel production. A comprehensive understanding of reoxidation mechanisms and the implementation of effective strategies are essential for achieving cleaner steel production. [ABSTRACT FROM AUTHOR]

It is herein considered a new product composed of solid–liquid dispersion of a conveniently formulated continuous casting powder in synthetic oil‐based esters, where hypothetical limit to consider this liquid slurry as a liquid powder is a mix with at least 50% in weight powder load preserving suitable fluidity for effective and stable pumping. After a relatively long and intense industrial application period, one of most critical points when using liquid powder for steel continuous casting proves to be mold feeding. This is mainly because of weird properties of such material which behaves as a non‐Newtonian fluid. A thorough rheological study on samples of liquid powder for continuous casting is carried out. Based on meticulous characterization of a set of laboratory samples, the dispersion flow curve is determined. Most commonly used rheological models are then tested for fitting with the experimental data. Sisko model is identified as the best fitting one. This model is then implemented to derive the system curve describing its behavior under its industrial application conditions. The mathematical process to apply Sisko model and its numerical solutions is explained. The results found are consistent with the field experience of the industrial application of the material under study. [ABSTRACT FROM AUTHOR]

Low‐basicity fluorine‐containing mold flux, which forms a porous slag film with NaF pores, is expected to solve the contradiction between heat transfer and lubrication in the continuous casting of peritectic steel. Herein, the kinetic mechanism and the influence of NaF gas formation based on the different fluorine raw materials (NaF, CaF2, and Na3AlF6) at 0.9 basicity and 6 wt% fluorine are investigated by the combination of experiments and calculations. The results show that CaF2 is the first to generate NaF gas at 1189 K, followed by Na3AlF6 (1238 K) and NaF (1328 K). NaF raw material produces the most NaF gas with the lowest activation energy in the three raw materials, due to high Na ion kinetic energy, the simple degree of polymerization, and Na‐F1 bonds. Correspondingly, NaF bubbles in the molten slag are the largest based on their aggregation. Na3AlF6 and CaF2 raw materials rank second and third, with F atoms primarily bonded as Al‐Fx and Ca‐Fx and the higher proportion of QSi−O−Al2$Q_{\text{Si} - \text{O} - \text{Al}}^{2}$ and QSi−O−Si4$Q_{\text{Si} - \text{O} - \text{Si}}^{4}$ structure. Notably, at 0.9 basicity and 6 wt% fluorine, Na3AlF6 as raw material generates a suitable amount of gas, making diffuse and fine NaF bubbles in the molten slag. [ABSTRACT FROM AUTHOR]

The instantaneous abnormal mold level fluctuation (IAMLF) has significant harmful effects on slab quality. This article proposes a prediction and control method for IAMLF. First, the data processed by difference method is used for the IAMLF prediction and stopper‐rod position prediction. Then, the bidirectional long short‐term memory (BI‐LSTM) is introduced to predict the IAMLF; the corresponding stopper‐rod position is predicted according to the mold level prediction result. BI‐LSTM can predict the IAMLF with the mean absolute error of 1.52 mm and the false alarm rate of 1.8%, and also performs well in predicting the stopper‐rod position with a mean absolute error of only 1.92 mm. Furthermore, the two prediction models are combined to form a closed loop, where the mold level fluctuation is predicted according to the industrial data processed by data difference method, and the stopper‐rod position is adjusted in advance to eliminate IAMLF. Finally, the fuzzy proportional‐integral‐derivative (PID) controller is used to control mold level based on the mold level and stopper‐rod position prediction results. The prediction accuracy of IAMLF reaches 98.4%, and the present proposed fuzzy PID controller can effectively prevent the occurrence of IAMLF with a success rate of 95.6%. [ABSTRACT FROM AUTHOR]

In this article, a brief review of the development of the Knudsen effusion mass spectrometric (KEMS) approach in the Theoretical Metallurgy Department of the KTH Royal Institute of Technology and in the in the Laboratory of Metallurgy of the Helsinki University of Technology and modifications of quadrupole model QMG420 mass spectrometers, is presented. The thermodynamic data obtained from vaporization of standards, such as NaCl, CsCl, B2O3, and Ag, and of the B2O3–Al2O3 and ZnO–P2O5 systems is compared with the data obtained using a magnetic MS1301 mass spectrometer. For the first time, composition of the vapor phase over the Dy2O3–DyF3, CaO–CaCl2, and Cu–Mg systems and the partial pressures of components at high temperatures are investigated. The experimental data obtained for the investigated systems are used for prediction of the vaporization processes and modeling of thermodynamic properties and high‐temperature phase equilibria in the multicomponent systems used in metallurgy. An account is given of the detailed studies of the vaporization processes and thermodynamic properties of some multicomponent systems composed of oxides, fluorides, and carbonates forming mold powders for continuous casting of steel. Some new directions of the ongoing studies by the KEMS method are summarized. [ABSTRACT FROM AUTHOR]

The effect of strand (S‐) and final (F‐) electromagnetic stirring (EMS) on solidification structure characteristic of a φ690 mm continuously cast round bloom has been investigated industrially and theoretically. The newly designed S1‐EMS equipped just below the foot zone takes great effect on both equiaxed ratio and distribution alignment, as well as central porosity. Larger current S1‐EMS leads to higher equiaxed ratio, more symmetrical equiaxed zone, and smaller diameter of central porosity, and the effect is much more obvious than conventional S2‐EMS and F‐EMS. It is also noticed that there should be a saturation effect of S1‐EMS on the promotion of equiaxed dendrite nucleation. The S2‐EMS is beneficial for the expanding of equiaxed zone and improving of central porosity. When S1‐EMS is weak, strong S2‐EMS results in more asymmetrical equiaxed zone. However, when S‐EMS is strong, strong S2‐EMS results in more symmetrical distribution of equiaxed zone. The F‐EMS takes a little impact on the expanding of equiaxed zone in the large‐sized round bloom, and almost no effect on the alignment. The central porosity, however, is improved by F‐EMS with the help of decrease in temperature gradient and compensation of solidification contraction. [ABSTRACT FROM AUTHOR]

In the continuous casting process, the heat transfer effect of secondary cooling plays an important role in the quality of the slab. The cooling intensity and cooling uniformity of the secondary cooling nozzle need more efficient spray cooling to achieve. Herein, the cold characteristics of different types of nozzles were compared. It is found that the second type of air mist nozzles have more uniform water density and striking force. On this basis, high‐temperature heat transfer experiments for casting billets were carried out to study the heat transfer coefficients of different air mist nozzles in the secondary cooling zone of continuous casting. It is found that the heat transfer coefficient increases as the distance of the temperature measurement point from the nozzle directly below increases. The heat transfer coefficients of the casting billet in both the jet and non‐jet zones are decreasing to varying degrees. When the temperature drops to 600 °C, the second type of air mist nozzle shows a faster temperature drop at the point of measurement, a smaller difference in time taken for temperature drop between jet and non‐jet zones, and faster and more uniform spraying, leading to a more significant trend of increasing heat transfer coefficient. [ABSTRACT FROM AUTHOR]

With the thinner of the automobile panel, the press crack defects caused by the large‐size calcium aluminate inclusions at the automakers become obvious. Herein, in order to stabilize the control of calcium aluminate inclusions in the molten steel, the vortex slag entrainment (VSE) of a 300 ton ladle is investigated by the numerical simulation. The effects of the steel throughput, cofferdam height close to the nozzle, and ladle bottom structure on the VSE are analyzed. Results demonstrate that the residual molten steel (RMS) in the ladle and the critical height of the vortex increase with the increasing of the steel throughput. The RMS increases with the increasing of the cofferdam height when the VSE occurs. When the cofferdam height is 50, 100, and 150 mm, the RMS are 4.71, 7.19, and 9.62 t at the initial time of the VSE with a 7.5 ton min−1 steel throughput. In addition, the industrial trial of transforming the flat bottom ladle into the slope bottom ladle is carried out to control the VSE and reduce the RMS. The average weight of the RMS after pouring 25 heats of the slope ladle bottom ladle is 1.85 t less than that of the flat bottom ladle. [ABSTRACT FROM AUTHOR]

Controlling the flow activity at the meniscus in the mold during the continuous casting of ultrathick slab is challenging due to the complex flow behavior, which is not extensively documented. Herein, a multiphase transient model of the ultrathick slab mold has been developed to describe the flow of molten steel, velocity distribution, and stream pattern at different submerged entry nozzle (SEN) outlets. The position of impact points and the fluctuation of liquid level are discussed as well. After ejecting from the port, the stream of the S‐shaped SEN splits into upper and lower streams. The upper stream moves to the liquid level, which improves the liquid level activity near the SEN. However, the reduced mainstream momentum alleviates the occurrence of slag layer exposure. Industrial application of the S‐shaped SEN results in uniform slag distribution and smooth casting operations. [ABSTRACT FROM AUTHOR]

Strand surface defects originate from the initial solidification of molten steel in continuous casting mold. This article investigates the initial solidification behavior during the continuous casting of 55SiCr spring steel billet using a novel mold simulator. First, the high‐frequency responding temperatures and high‐frequency heat fluxes across the mold corner and hot face are calculated by the 2D‐inverse heat conduction program mathematical model and the fast Fourier transformation, and the results indicate that the temperature variations and heat flux fluctuations around mold corner are stronger than those at mold hot face. Then, the characteristic heat fluxes around the meniscus at mold corner and hot face are analyzed, and their four corresponding signals are discussed with the help of power spectral density analysis. The average solidification factor K for shell corner is greater than shell face, which indicates that the cooling intensity of shell at corner is stronger due to the two‐dimensional heat transfer near mold corner, as demonstrated by heat transfer and dendrite structure analysis. Finally, the interrelations between the shell profile, mold oscillation, heat flux change rate, high‐frequency heat flux, temperature change rate, and high‐frequency temperature for the two cases are discussed. [ABSTRACT FROM AUTHOR]

In the course of the decarbonization of steel production, electric steel production will continue to gain importance. The processing of low‐quality scrap will also play an important role, which may lead to an increase in the content of so‐called tramp elements in steel production and further processing. This article examines the effect of the elements Cu, Sn, and Ni on the formation of surface cracks under the conditions of the continuous casting process. Results of an in situ bending test are compared with the results of the experimental simulation of high‐temperature oxidation and thermodynamic analysis based on the CALculation of PHase Diagrams (CALPHAD) approach. For a temperature of 900 °C, an equivalent Cu content of 0.20 wt% must be considered as the critical upper limit. The presumable reason is the existence of Cu‐ and Sn‐rich liquid phases at the austenite grain boundaries. The results clearly show the effect of the investigated elements but also point to the importance of the gas atmosphere and cooling conditions on the results. This can be a groundbreaking result for extending the process window for casting steels with increased tramp element contents. [ABSTRACT FROM AUTHOR]

Summary: The accurate characterisation of centreline segregation requires precise measurements of composition variations over large length scales (10−1$^{-1}$m${\rm {m}}$) across the centreline of the cast product, while having high resolution, sufficient to quantify the significant composition variations between dendrites due to microsegregation at very small length scales (10−5m$^{-5}{\rm {m}}$). This study investigates the potential of a novel microscopy technique, named Synchrotron Micro X‐ray Flurorescence (SMXRF), to generate large‐scale high‐resolution segregation maps from a steel sample taken from a thin slab caster. Two methods, Point Analysis and Regression Analysis, are proposed for SMXRF data calibration. By comparing with the traditional Laser‐Induced Breakdown Spectroscopy (LIBS), and Electron Probe Micro Analyser (EPMA) techniques, we show that SMXRF is successful in quantitative characterisation of centreline segregation. Over large areas (e.g. 12 ×$\times$ 16 mm2${\rm {mm}}^2$) and at high resolution (10–50 μm$\mu\text{m}$ pixel size) various techniques yield comparable outcomes in terms of composition maps and solute profiles. The findings also highlight the importance of both high spatial resolution and large field of view to have a quantitative, accurate, and efficient measurement tool to investigate segregation phenomena. [ABSTRACT FROM AUTHOR]

An experimental study is conducted to reveal the formation mechanism of transverse corner cracks by analyzing the metallurgical structure, crack morphology, and hot ductility. The results reveal that the corner temperature of the billet tends to be lower during mold solidification, leading to the formation of grain boundary low‐plasticity ferrite. Additionally, during the straightening process, the corner temperature of the billet falls into the serious low‐temperature brittle zone with temperature lower than 850 °C. These two factors contribute to the formation and propagation of cracks along the grain boundary ferrite under straightening forces. Therefore, after the verification of mold simulation test and industrial trial, the temperature at billet (section size 150 × 150 mm2) corner is improved by increasing the mold chamfer radius from 6 to 12 mm. This adjustment ensures that the straightening temperature at billet corner elevated from 830 to 880 °C, remaining outside the serious low‐temperature brittle zone, and the maximum depth of corner cracks decreases from 741.49 to 344.89 μm. [ABSTRACT FROM AUTHOR]

This study identifies optimal cooling rates and critical strain thresholds to prevent cracking in Cr12MoV billets during continuous casting through thermoplastic experiments, high‐temperature tensile tests, and a thermal–mechanical coupled simulation model. The result shows that the critical strain (dimensionless) for corner crack propagation at temperatures of 750, 800, and 850 °C are determined to be 0.125, 0.132, and 0.147, respectively. The critical strain for internal crack formation is found to be 0.03. The simulation results indicate that as the billet enters the first straightening roll, the corner strain is 0.035 and the central strain is 0.025. Upon exiting the fourth straightening roll, the corner strain increases to 0.038, while the central strain decreases to 0.021. Through simulation and high‐temperature confocal in situ observation, it can be concluded that a surface cooling rate of ≥5 °C s−1 effectively prevents cracks during the bending and straightening stage of continuous casting. [ABSTRACT FROM AUTHOR]

The crystallization process of low melting point CaO–SiO2–Al2O3–MgO system inclusions during the continuous casting and hot rolling process greatly affects the deformability of inclusions. The effect of Al2O3 and MgO contents on the crystallization characteristics of CaO–SiO2–Al2O3–MgO system melts representing the typical oxide inclusions in Si–Mn deoxidized steels is systematically investigated. The continuous cooling transformation and time–temperature transformation experiments are carried out. The results reveal that the increase of Al2O3 contents restrains the crystallization process of the melt, whereas the crystallization tendency of the melt is promoted with the increase of MgO contents. The precipitated phases are predominately 2CaO·MgO·2SiO2 and 3CaO·MgO·2SiO2, and the primary crystalline phase is unaffected by the changes of Al2O3 and MgO contents. To obtain low melting point plasticized inclusions with limited crystallization ability, it is recommended to control the Al2O3 and MgO contents greater than 15 wt% and below 5 wt%, respectively. The isothermal treatment is suggested to be controlled within a proper temperature range (1175–1250 °C) to decrease the crystallization kinetics. The oxide system's viscosity change is the limiting kinetic factor in the crystallization process, and it can be utilized to predict the system's crystallization tendency. [ABSTRACT FROM AUTHOR]

Low‐basicity fluorine‐containing mold powder, which forms a porous slag film with NaF pores, is expected to solve the contradiction between heat transfer and lubrication during the continuous casting of peritectic steel. Herein, to study the influences of different fluorine raw materials (NaF, CaF2, and Na3AlF6) on NaF vaporization, thermodynamic calculations are carried out by FactSage 8.1 during mold powder melting from 600 to 1600 °C. The results show that CaF2 is the first producing NaF gas, followed by Na3AlF6 and then NaF as the temperature increases. With the same mass of fluorine addition, NaF produces the highest amount of NaF(g), followed by Na3AlF6 and CaF2. Furthermore, the effects of basicity (%CaO/%SiO2) and Al2O3 contents on NaF vaporization are investigated. Additionally, different fluorine raw materials and Al2O3 components that can form porous slag films at low basicity (from 0.7 to 1.1) are also obtained. Therefore, this work can be used to guide mold powder design for peritectic steel. [ABSTRACT FROM AUTHOR]

The submerged entry nozzle (SEN) is an indispensable functional structural ceramic in the current continuous casting production. The stability and safety of the SEN is very important during the casting process. In this article, the functional failure of the SEN during the continuous casting process of the bearing steel GCr15 is studied. The results show that the functional failure of the SEN during the bearing steel GCr15 casting process is caused by the clogging inside the SEN which is led by the low cleanliness and the high impurities n the molten steel. The clogging in the SEN can be divided into solidified steel area, loose area, dense area, and surface area. To improve the castability of bearing steel or other high‐cleanliness steel, it is necessary to strengthen the refining process and treatment effect, strengthen the sealing and the effect of the protective casting of the molten steel, and moderate optimization of nozzle materials or the application of external fields on the SEN. [ABSTRACT FROM AUTHOR]

To comprehensively comprehend variation of strip shape (strip feeding depth and maximum steel sheath cross‐sectional area) under different process parameters (strip feeding speed, strip oscillation frequency, strip amplitude, molten steel superheat, strip width, and strip thickness), a mathematical model of feeding strip process has been developed herein. Flow near steel strip is analyzed. Meanwhile, the qualitative relationship between strip shape and process parameters is derived based on energy conservation within the system of molten steel and steel strip. The results show that strip feeding depth is positively correlated with strip feeding speed, strip width, and strip thickness, while it's negatively correlated with strip oscillation frequency, strip amplitude, and molten steel superheat; maximum steel sheath cross‐sectional area is positively correlated with strip width and strip thickness, while it's negatively correlated with strip feeding speed, strip oscillation frequency, strip amplitude, and molten steel superheat. Based on the calculated results, the quantitative relationships are proposed to predict the strip feeding depth and maximum steel sheath cross‐sectional area with aforementioned process parameters, which are suitable for the situations that the strip tip is located between the outlet of submerged entry nozzle and the end of the liquid core. [ABSTRACT FROM AUTHOR]

Al–Mg–Si aluminum wires for overhead power transmission have extensive applications in industry and daily life. Herein, superior strength and electrical conductivity combinations in the aged cold‐drawn Al–Mg–Si–Ce–Cu wires fabricated by continuous casting and rolling are achieved. The cold‐drawn wires exhibit high strength and electrical conductivity combinations of 383 ± 2 MPa, 51.16 ± 0.23% International Annealed Copper Standard (IACS); 373 ± 3 MPa, 51.98 ± 0.25%; and 357 ± 3 MPa, 53.16 ± 0.11% IACS, respectively, when aged at 160, 170, or 180 °C for 24 h. Subgrain boundaries are introduced into alloys by continuous casting and rolling and cold drawing, causing significant lattice distortion within the grains and providing sites for the nucleation of precipitates. Moreover, high‐angle‐annular dark‐field scanning transmission electron microscopy and density functional theory results show that Ce atoms could enter the lattice of β" and replace the Si3 sites, which is energetically preferred. The underlying mechanisms for achieving superior strength–electrical conductivity combination are to introduce subgrain boundaries via continuous casting and rolling and cold drawing for promoting the transformation of solid solution atoms to finely dispersed precipitates, which significantly reduces the scattering of electrons and hence improves the electrical conductivity. This work provides a new strategy for designing high‐strength and high‐conductivity aluminum alloy wire conductors. [ABSTRACT FROM AUTHOR]

Continuous casting of aluminum (Al) deoxidized steels demands careful inspection due to the occurrence of submerged entry nozzle (SEN) clogging, leading to unexpected production stops. Recognizing the castability of a specific “cast” by monitoring the condition of the SEN is essential for uninterrupted casting. With this information prior to casting, operators can take preventive action against possible clogging occurrences, thus reducing unplanned downtimes. In response to the severe implications of SEN clogging, this work introduces a novel way to forecast castability of Al‐killed steels. A hybrid model is proposed that integrates the adaptive neuro‐fuzzy inference system (ANFIS) and long short‐term memory (LSTM) networks. The output of the model helps to anticipate the event of clogging by analyzing both the past condition of the SEN and changes in the steel chemistry during the transport of the steel ladle from refining to the casting process. A comprehensive analysis of 150 casts helped to build the ANFIS algorithm for estimating the castability index (CI) parameter from steel chemistry. LSTM algorithm is used as a subsequent step to forecast castability in the next 20–25 min. Discrepancies between the predictive response and the actual conditions are reported. Although the real‐time implementation of the proposed model is the ultimate goal, the focus of this work was to present the methodology and demonstrate its potential. [ABSTRACT FROM AUTHOR]

The flow pattern in an opaque mold cannot be readily visible, and worker experience plays a major role in controlling it, even though it has a significant impact on slab quality in a continuous casting (CC) mold. An Eulerian–Eulerian two‐fluid model is used to comprehensively study the two‐phase flow of argon and molten steel in a slab CC mold. The positions of vortex centers in upper/lower recirculation zones and the impingement point of jet flow on the narrow face of mold are identified and their distribution is analyzed. The interactive effects of casting speed, argon flow rate, and immersion depth of the submerged entry nozzle (SEN) on the flow pattern inside the mold are revealed. 2D and 3D flow pattern regimes are plotted and the boundary lines and boundary surfaces are fit with exponential functions and ternary functions, respectively. To obtain a double roll flow in the slab CC mold investigated, the relation among argon flow rate (Qg$Q_{\text{g}}$), casting speed (Cl$C_{\text{l}}$), and the immersion depth of the SEN (SSEN$S_{\text{SEN}}$) should satisfy, Qg<−0.2799SSEN−119.3086Cl+0.2811SSENCl+0.0003SSEN2+51.2864Cl2+67.6296$Q_{\text{g}} &amp;amp;amp;amp;amp;amp;lt; - 0.2799 S_{\text{SEN}} - 119.3086 C_{\text{l}} &amp;amp;amp;amp;amp;amp;amp;plus; 0.2811 S_{\text{SEN}} C_{\text{l}} &amp;amp;amp;amp;amp;amp;amp;plus; 0.0003 S_{\text{SEN}}^{2} &amp;amp;amp;amp;amp;amp;amp;plus; 51.2864 C_{\text{l}}^{2} &amp;amp;amp;amp;amp;amp;amp;plus; 67.6296$. [ABSTRACT FROM AUTHOR]

Herein, the effects of the bottom shape of the submerged entry nozzle (SEN) on the molten steel flow and size distribution of argon bubbles are analyzed in a steel continuous casting slab strand using multiple‐size‐group approach. The type of nozzle bottom includes the well bottom, flat bottom, and mountain bottom. Most of argon bubbles are larger than 4.5 mm inside the SEN and the mold at the three types of nozzles. The frequency distribution of bubbles inside the SEN increases from 28.29% to 32.65% and 35.74% for 5.0–5.5 mm bubbles and decreases from 53.71–50.49% and 47.38% for 5.5–6.0 mm bubbles with the nozzle bottom varied from the flat to mountain and well shape, respectively. The number density of argon bubbles with 4.0–5.5 mm diameter in the mold decreases and increases for 5.5–6.0 mm bubbles with the nozzle bottom varying from the well to flat and mountain shape, respectively. In addition, the results of the industrial trials show that inclusions adhesion and aggregation at the bottom of the nozzle are eliminated using the flat bottom SEN casting. Meanwhile, the mechanism of SEN clogging under the different types of nozzle bottoms is analyzed. [ABSTRACT FROM AUTHOR]

To prevent thermal cracks on steel slabs during the stacking, scarfing, and grinding processes after continuous casting, an optimized machine learning (ML) model to predict the impact absorption energy (EIA) of steel slabs is developed. A total of 1,421 experimental EIA data are collected from Charpy impact tests at slab temperatures 25 ≤ TS ≤ 400 °C, then ML models that considered 15 steel‐component variables and temperatures are developed. Four ML models are developed and their accuracies are compared. The optimized deep neural network algorithm predicts EIA most accurately with root mean squared error of 10.82 J and coefficient of determination (R2) of 0.992. Then the predicted EIA is used as the criterion to predict the occurrence of thermal cracks in slabs that are actually produced by a continuous casting process. At TS = 250 °C, cracking does not occur when the steel has predicted EIA > 175 J. The use of the developed model to predict EIA can prevent the formation of thermal cracks in slabs produced by continuous casting, and enable optimization of the cooling method and scarfing methods that precede the next process after continuous casting of slabs. [ABSTRACT FROM AUTHOR]

Slag entrapment from metal–slag interface during continuous casting operations has been a major area of concern for steelmakers globally. The presence of inactive regions in the upper region of the mold poses another challenge. Proper flow behavior of the molten metal coming out of the nozzle in the mold is required to overcome these challenges. Nozzle design greatly affects the flow pattern of the molten steel inside the mold. The present investigation is an attempt to study the flow and solidification behavior in a slab caster mold with the use of a novel‐designed hexa‐furcated nozzle using numerical investigation results. The casting speed and submerged entry nozzle (SEN) depth are varied to study the effect of these parameters on minimizing the inactive zones in the mold and the steel/slag interface fluctuations. The results show that the interface fluctuation increases at higher casting speed and lower SEN depth. The residence time distribution (RTD) analysis was also performed for different cases to investigate the flow behavior. The validation of the fluid flow and RTD curve inside the computational domain is carried out with the use of physical modeling. [ABSTRACT FROM AUTHOR]

To reduce the solidification structure defects and the macrosegregation of the Φ300 mm continuous casting round bloom, the pulsed magneto‐oscillation (PMO) treatment is added at the secondary cooling zone. A numerical model for calculating the pulsed electromagnetic field, flow field, and temperature field in continuous casting is established, and the coupling simulations of multiphysical fields under different casting parameters and PMO parameters are performed. Their influence on solidification process and the appropriate parameters are discussed. The industrial experiments conducted under the recommended parameters yield good results. Industrial experiments show that when the peak current is increased from 1350 to 1550 KIA and the casting speed is increased from 0.75 to 0.90 m min−1, PMO can increase the equiaxed grain zone and reduce the carbon macrosegregation of the bloom. Moreover, at high casting speed, PMO treatment can significantly promote columnar‐to‐equiaxed transition and increase the width of mixed grain zone. [ABSTRACT FROM AUTHOR]

The types, distribution, morphology, orientation, growth, and aggregation mechanism of primary carbides in the continuous casting slab of 6Cr13 high‐carbon martensitic stainless steel are investigated. In the results, it is shown that M7C3 carbides precipitate from the liquid steel at the end of solidification. The area fraction of primary carbides in the slab thickness direction shows an overall decreasing trend from the center to the edge. And, the closer to the center region, the greater the difference in carbide distribution due to the presence of spot segregation defects. At 1/8 thickness and edges in the slab, the fast cooling rate and fine dendrites make the carbide morphology to be a small‐sized brain like that aggregates a large number of spherical carbides. At 1/4 thickness in the slab, blocky, fibrous, and spherical carbides precipitate successively and eventually aggregate together. At 3/8 thickness and center in the slab, the cooling rate is slower and spot segregation defects are randomly distributed in this region. The carbide morphology is mostly small‐sized brain like in the non‐spot segregation region. However, the alloying elements are highly supersaturated and the carbides can grow sufficiently to form less oriented, large‐sized brain‐like carbide in the spot segregation region. [ABSTRACT FROM AUTHOR]

Bias flow of molten metal in slab mold caused by unstable flow from submerged entry nozzle can deteriorate the slab quality during continuous casting. In this study, a novel electromagnetic swirling flow in nozzle (EMSFN) technique, which utilizes electromagnetic force to stabilize the flow in the nozzle and subsequently control the flow in the mold, is proposed. The mechanism for controlling unstable flow through EMSFN is explored through numerical simulation and water model experiments. In the results, it is shown that the molten steel is rotated under the effect of magnetic field and flows into the mold along the upper edge of the nozzle outlet, which weakens the impact of molten steel on the bottom of nozzle and stabilizes the outflow from nozzle. The flow field is consistently symmetrical on both sides of the nozzle. The impact depth of molten steel flowing down along the narrow sides of the mold on both sides is greatly reduced. The surface velocity on both sides of the nozzle changes uniformly. The range of surface velocity variation with EMSFN is only 10% of that with a conventional nozzle. The EMSFN technique can help prevent slag entrapment and improve the flotation of inclusions and bubbles. [ABSTRACT FROM AUTHOR]

The formation of defects such as cracks in continuous casting deteriorates the quality of cast products and efficiency of steelmaking. To evaluate the risks and identify the root causes of defect formation, phenomenological quality criteria computed with a solidification and microstructure model known as InterDendritic Solidification (IDS) have previously been applied. This approach is computationally efficient and provides a fundamental perspective to defect formation in continuous casting. The aim of this work is to study the capabilities of these criteria as features in predicting transverse cracking with interpretable machine learning models. IDS is coupled with a heat transfer model known as Tempsimu to simulate the continuous casting process. Measured compositions are utilized in the simulations and defects reported at a steelmaking plant are used as labels in classification. Logistic regression, decision tree, and Gaussian Naïve Bayes classifiers are developed to predict transverse cracking in peritectic C–Mn, low‐carbon B–Ti microalloyed, and peritectic Nb‐microalloyed steels. The corresponding balanced accuracies of the best classifiers from cross‐validation are 92%, 94.6%, and 82.8%. Due to the good performance and the interpretability of the developed classifiers, the fundamental causes of transverse cracking and possibilities of avoiding it by changes in the compositions are identified. [ABSTRACT FROM AUTHOR]

The continuous casting of Al‐killed Ti‐stabilized interstitial free steels is often affected by clogging. By today, the mechanism behind this phenomenon is not entirely clarified. The active tracing method, which involves the direct addition of rare‐earth elements (REEs), enables tracking of nonmetallic inclusions (NMIs) over process time. Due to the high oxygen affinity of these elements, preexisting NMIs are partially reduced and marked by this tracer. Using scanning electron microscopy with energy‐dispersive spectroscopy, it is possible to differentiate such labeled NMIs from particles formed at later stages in the process by the absence of these tracing elements. Active tracing is used in industrial and laboratory settings to trace preexisting alumina NMIs with La or Ce. In the investigation, it is revealed that the number of small NMIs increases after the addition of REEs, and subsequently, the size increases again after FeTi is alloyed. In both settings, traced and untraced Al–Ti oxides are found. The separation tendency of traced NMIs is studied over time by analyzing the composition of the slags. Furthermore, the impact of deoxidation products on the formation of the clogging layer within the submerged entry nozzle is investigated, indicating that these NMIs contribute to its formation. [ABSTRACT FROM AUTHOR]

The morphology of carbides, the distribution of alloying elements, and the dissolution of primary carbides in 6Cr13 continuous casting slabs during the high‐temperature homogenization process are studied herein. The results show that severe segregation of alloying elements exists at the center of the cast slabs, accompanied by large, interconnected primary carbides in the form of a network. Large‐sized reticulated primary carbides are difficult to completely dissolve and eliminate during homogenization treatments. Large‐sized primary carbides will dissolve along the contours and the joints between the carbides when the temperature of high‐temperature homogenization does not exceed 1250 °C and the time does not exceed 1 h. The carbides that had broken off will precipitate again along the original contour in the form of large‐sized brain‐like carbides beyond this temperature and time. In situ observation of the high‐temperature homogenization process reveals that when the slab is heated to 1200 °C, the local liquid phase starts to be generated around the carbide. Cr atoms diffuse into the matrix through the liquid–matrix interface; it will accelerate the high‐temperature homogenization process and improve the segregation of alloying elements around carbides. [ABSTRACT FROM AUTHOR]

Heat transfer from the solidified shell to the mold, especially in the meniscus region, significantly affects the surface quality of the strand and the stability of the continuous casting process. The mold slag film serves as the sole heat transfer medium between the shell and the mold, and its performance and structure have a substantial impact on the heat transfer efficiency. Thus, since the 1980s, various testing methods are developed to investigate the heat transfer performance of the slag film, including the pouring method, immersion method, parallel plate method, and mold experiment. In this article, the principles, characteristics, and main study results of these methods are reviewed, and the existing issues are highlighted in these methods. Furthermore, specific requirements that shall be satisfied in future research on the heat transfer of slag film are presented. The new approach for testing heat transfer in slag film necessitates ensuring consistency in the heat flux, surface temperature of the shell, interfacial thermal resistance, and thickness and cooling rate of the slag film, aligning with those observed in a mold. This consistency is crucial to ensure the comparable structure and heat transfer characteristic between the experimental and industrial slag films. [ABSTRACT FROM AUTHOR]

During the thin slab continuous casting process of silicon steel, electromagnetic stirring (EMS) can control the flow, heat transfer, and solidification of molten steel through electromagnetic force. Herein, a 3D mathematical model coupling the fluid flow, heat transfer, solidification, and the electromagnetic field is built. The effects of varied current intensities on the flow, heat transfer, and solidification of molten steel in the thin slab under secondary EMS are explored based on applying the electromagnetic brake in the mold region. In the findings, it is demonstrated that increasing the current intensity increases the flow rate and vorticity of the molten steel in the second cooling zone, eliminating the superheating phenomenon and improving the uniformity of the molten steel's temperature distribution. Meanwhile, based on the nucleation and growth parameters determined from thermal simulation experiments, the cellular automation finite‐element model is used to simulate the microstructure evolution during the solidification of thin slab. In the results, it is shown that the stirring energy increases when the current intensity increases, potentially promoting equiaxed crystal growth and grain refinement. Compared to the production sample, a reasonable qualitative agreement is achieved for the grain morphology, equiaxed crystal ratio, and columnar to equiaxed transition. [ABSTRACT FROM AUTHOR]