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Mold level fluctuation has always been one of the key factors in slab quality control. Abnormal fluctuations can easily cause slag entrainment and form surface defects of hot-rolled and cold-rolled steel sheets, thus reducing the product qualification rate. In this study, mold level fluctuation data was collected during Ti-bearing Interstitial Free (IF) steel in a stable state for a complete casting sequence in a certain factory. The mold level fluctuation is analyzed using the discrete wavelet transform (DWT) method, and its characteristic values are classified based on frequency. Combined with the corresponding process parameters, the causes were traced during abnormal fluctuation characteristic values. It was found that the formation of abnormal mold level fluctuation mainly comes from two aspects. On the one hand, there are random fluctuations in the low-frequency band, and on the other, there are clustered fluctuations in the relatively high-frequency band. There is always a rising trend in mold liquid levels when there are random abnormal fluctuations in the low-frequency band. There is a delay of approximately 0.1412 s in the feedback of the stopper rod to the mold level fluctuation. The major causes of the low-frequency random fluctuations include variations in the tundish weight, casting speed, and mold width, and the clogs peeling. The clogging of the side hole at the submerged entry nozzle (SEN) is the primary cause of abnormal clustered fluctuations in the high-frequency band. These are certain relationships with clogging, whether it is high-frequency clustered or low-frequency random abnormal fluctuations. Without a doubt, this is a crucial link that limits the slab quality.

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]

High strength low alloy (HSLA) steels with tempered martensite microstructure are widely applied in the offshore industry such as fasteners. The subsea environment conditions are quite favorable for severe hydrogen embrittlement (HE). Their good hardenability influences the achievement of excellent mechanical properties. Three different steelmaking routes such as continuous casting (CC), conventional ingot casting (CIC) and electroslag remelting (ESR) were investigated to verify the influence on the AISI 4140 steel microstructure and the HE susceptibility. Electrochemical hydrogen permeation tests were correlated with the microstructure obtained from each route that presented different levels of segregation bands. The CC process was responsible for the appearance of a high density of non-metallic inclusions (NMIs) like manganese sulfide (MnS) and impurities in segregation regions that increased the HE degree. The ESR route presented the best mechanical behavior due to the lowest reduction in ductility for hydrogenated uniaxial tensile test conditions and, consequently, the highest resistance regarding the HE. • Hydrogen embrittlement in high strength low alloy produced from steelmaking routes. • Hydrogen diffusivity and solubility in the high strength low alloy AISI 4140. • Effects of segregation bands on the hydrogen embrittlement in the high strength low alloy AISI 4140. [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]

This paper proposed a prediction algorithm for the degraded actuator taking into account the impact of estimation error of hidden index in the closed-loop system. To this end, a unified prediction framework is established to evaluate the hidden degradation information and recursively update the degradation model parameters simultaneously. The advantage is that the prediction framework can comprehensively compensate the estimation error of hidden degradation index caused by system uncertainty. To jointly estimate the degradation information in avoidance of the impact of system uncertainty, a modified adaptive Kalman filter is designed, and the proof of stability is provided. With the priori estimate from the filter, the degradation model parameters are updated by the inverse filtering probability based on Bayes' theorem. It is followed by the computation of the remaining useful life (RUL) prediction utilizing aforementioned hidden degradation information and the latest degradation model. The effectiveness of the proposed RUL prediction algorithm is demonstrated by the degraded actuator in the continuous casting process. • A novel prediction framework is designed for degraded actuator in closed-loop system. • Adaptive degradation model is established by modified adaptive Kalman filter. • The estimation error of hidden degradation index is integrated. • The stability of optimized adaptive Kalman filter is proven. • Recursive prediction algorithm is performed without full life data. [ABSTRACT FROM AUTHOR]

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Steel-making and continuous casting (SCC) processes are considered the main bottlenecks in the steel industry. We consider planning and scheduling problems in SCC processes and provide an overview of the literature with our commentary. The planning problem has as goal to create out of customer orders production units for the various production processes. The scheduling problem assigns these production units to the production facilities over different time intervals. We review a large number of planning and scheduling papers and propose two basic models for the planning and the scheduling problems that incorporate the most common and essential features. We describe for each problem the respective constraints and objectives as well as the practical implications in an actual production environment. We also analyse the methodologies used in their solutions, including decomposition strategies. In the last section, we present the conclusions of our survey and propose new research directions. [ABSTRACT FROM AUTHOR]

Longitudinal crack defects are a frequent occurrence on the surface of thin slabs during the high-speed continuous casting process. Therefore, this study undertakes a detailed analysis of the solidification characteristics of hyper-peritectic steel thin slabs. By establishing a three-dimensional heat transfer numerical model of the thin slab, the formation mechanism of longitudinal cracks caused by uneven growth of the initial shell is determined. Based on the mechanism of longitudinal crack formation, by adjusting the performance parameters of the mold flux, the contradiction between the heat transfer control and lubrication improvement of the mold flux is fully coordinated, further reducing the incidence of longitudinal cracks on the surface of the casting thin slab. The results show that, using the optimized mold flux, the basicity increases from 1.60 to 1.68, the F- mass fraction increases from 10.67% to 11.22%, the Na2O mass fraction increases from 4.35% to 5.28%, the Li2O mass fraction increases from 0.68% to 0.75%, and the carbon mass fraction reduces from 10.86% to 10.47%. The crystallization performance and rheological properties of the mold flux significantly improve, reducing the heat transfer performance while ensuring the lubrication ability of the molten slag. After optimizing the mold flux, a surface detection system was used to statistically analyze the longitudinal cracks on the surface of the casting thin slab. The proportion of longitudinal cracks (crack length/steel coil length, where each coil produced is about 32 m long) on the surface of the thin slab decreases from 0.056% to 0.031%, and the surface quality of the thin slab significantly improves. [ABSTRACT FROM AUTHOR]

The effect of Al or Cu content on the microstructure and mechanical properties of continuous casting and extrusion Zn alloys has been studied by a room temperature tensile test, X-ray diffraction, and scanning electron microscope. With the increase in Al content, the microstructure of continuous casting and extrusion Zn alloys slightly coarsens, and the lamellar eutectic structure increases. The changes in the above structural factors result in a slight decrease in strength and a significant increase in the elongation of Zn-Al alloys. The strength of Zn alloys increases as the Cu content increases due to the increased content and size of the second phase in the Zn alloys. This means that the mechanical properties of Zn alloys can be adjusted by a continuous casting and extrusion process, and the improvement of equipment capacity can improve the structure and morphology of the alloys. [ABSTRACT FROM AUTHOR]

In the continuous casting process, clogging of the submerged entry nozzle (SEN) significantly increases the risk of slag entrainment and the incidence of defects in the slab. A water model at 0.6 scale was created for this study. Acrylic glass particles of different sizes were pasted on the inner walls of the SEN to simulate different clogging rates. Wavelet transform combined with energy was used to analyze the mold level fluctuation. The mold flow field and the distribution of the mold slag were observed. According to the findings, it is necessary to monitor fluctuations on both sides of the narrow face of the mold (NF). An accurate assessment of the bias flow may be made by the wavelet transform combined with energy to analyze the mold level fluctuation at the NF on both sides of the mold. This is a promotion and innovation in traditional fluctuations analysis methods. The frequency at NF is higher on the side with a larger clogging rate when asymmetric clogging occurs in SEN. The upper circulating flow (UCF) velocity on the side with lower clogging is more significant. The mold slag cannot completely cover the molten steel because of the velocity difference. The UCF vortex center on the severe side of the clogging shifts toward the NF as the asymmetric clogging increases, and the velocity of the molten steel there gradually rises. This increases the frequency of slag entrainment and the range of molten steel exposure. [ABSTRACT FROM AUTHOR]

In the current study, a three-dimensional mathematical model was established, integrating with the large eddy simulation (LES) turbulent model, the volume of fluid (VOF) multiphase model, and the magnetohydrodynamics (MHD) model to investigate the influence of the mold electromagnetic stirring (M-EMS) on the multiphase flow field in a slab continuous casting mold. The results indicated that the application of M-EMS altered the flow pattern of molten steel in the mold, thereby intensifying the meniscus fluctuation. Moreover, it increased the probability of the slag entrainment, elevating the net slag entrainment rate by nearly ten times. With the increase in current intensity, the stirring effect of M-EMS not only intensified the meniscus fluctuation but also increased the net slag entrainment rate. A user-defined function (UDF) was employed to quantify the number, size, and spatial distribution of entrained slag droplets. The increase in current intensity led to an increase in the number of large-size entrained slag droplets. The greater stirring intensity at a current intensity of 600 A led to the fragmentation of the larger entrained slag droplets into several smaller droplets, thus the proportion of large-size entrained slag droplets was reduced. The stirring effect of the electromagnetic force led to the formation of numerous vortices along the centerline of the mold thickness. Consequently, this phenomenon led to an increase in the occurrence and probability of slag entrainment along the centerline of the mold thickness. Under the influence of M-EMS, the effect of slag viscosity on the multiphase flow field appeared to be less significant, while an increase in viscosity reduced the slag entrainment rate. The submerged entry nozzle angle directly influenced the flow field in the upper circulation, consequently affecting the slag entrainment rate. The size distribution of entrained slag droplets remained unaffected by the slag viscosity and the nozzle angle. [ABSTRACT FROM AUTHOR]

Breakout is the most destructive accident that interrupts the smooth production process of continuous casting, which needs to take effective and accurate measures to predict. In light of the "Y" form tear trace left at slab surface when sticking breakout happens, computer vision techniques are used in this paper to convert the one-dimensional temperature signal measured in time sequence by thermocouples into two-dimensional temperature rate thermography of mold copper plate, forecasting breakout by capturing the "Y" shape sticking region characteristic in thermography. In an effort to process big quantity of thermography data in a precise and stable way and differentiate between sticking breakout sample and normal condition sample, deep convolutional neural network model is constructed for recognizing between these two, and we develop a mold breakout prediction model based on identifying abnormal visual sticking region through CNN (convolutional neural network). The test result indicates that model is able to detect sticking breakout samples out of different temperature patterns and exclude normal condition samples at the same time. With achieving a 100 pct prediction accuracy for true sticking breakout, fine-grained classification model obtains a lower false positive rate compared to transfer learning model and a better generalization performance, offering a new train of thought into establishing data-driven abnormality detection methods during continuous casting process. [ABSTRACT FROM AUTHOR]

As an important refractory material in the continuous casting process, the clogging of submerged entry nozzle (SEN) can negatively affect the quality of the slab. In this paper, the effect of electric current pulse (ECP) on the interfacial reaction between molten steel and SEN during continuous casting of ultra-low carbon steel was studied. The results show that the application of ECP can effectively inhibit the adhesion and growth of clogging. After employing ECP, the structure of clogging at the interface changes and its density increases. The newly formed clogging is more stable and can effectively resist the impact of high-speed molten steel. In particular, applying ECP improves the qualification rate of liquid level fluctuation on the mold. The number of large-size inclusions and defects in the slab are significantly reduced, which has a positive effect on improving the quality of the slab and prolonging the service life of the SEN. [ABSTRACT FROM AUTHOR]

Three-dimensional mathematical model was established to investigate the solidification behavior during the continuous casting of a round bloom with the diameter of 0.7 m, where a novel swirling flow submerged entry nozzle (SEN) combined with mold electromagnetic stirring (M-EMS) method was used. The results show that an impinging flow phenomenon, which was normally formed in conventional single-port SEN casting, was effectively eliminated by adopting the new method. Molten steel from the swirling flow SEN port uniformly moved to the solidification front, which improved the dissipation rate of molten steel super-heat. When the rotational direction of the swirling flow in SEN was in the same direction as M-EMS, the super-heat of molten steel in mold can be decreased by 5 K, compared to the use of a conventional SEN with M-EMS. As the current intensity decreased from 310 to 100 A, the super-heat of molten steel in the mold center region was reduced by 3 K. This is due to that the shielding effect of M-EMS on rotational flow momentum from the swirling flow SEN became weak as the stirring intensity decreased. In addition, molten steel temperature near the meniscus under the current intensity of 310 and 100 A was 1787 K and 1790 K, respectively. The solidified shell thickness obtained by using 100 A current intensity was about 1 × 10−3 m larger than that of 310 A current intensity. [ABSTRACT FROM AUTHOR]

Strand electromagnetic stirring (SEMS) is widely applied in thin-slab continuous casting to promote the equiaxed crystal ratio (ECR). However, the effects of alternate electromagnetic stirring on the evolution of solidification macrostructure and ECR remain poorly understood. And the formation of the equiaxed crystal region beneath the stand and equiaxed-to-columnar transition (ECT) have been overlooked in most previous models. This study first introduces a novel equiaxed-columnar solidification model to comprehensively analyze the effects of alternate electromagnetic stirring in thin-slab continuous casting. A complete macrostructure feature of the slab, including the equiaxed crystal region beneath the strand, ECT, well-developed columnar dendrites, columnar-to-equiaxed transition, and center equiaxed crystal zone, could be simulated accurately. The multiphase model was validated by the measured ECR and columnar growing direction from a pickling corrosion experiment. Results showed that alternate stirring could improve the ECR effectively. The ECR was increased by 26 pct compared to the one-way stirring when the switching period of alternate stirring was 8–12 seconds. A multi-vortex flow structure was observed in the secondary cooling zone, which could increase the residence time of the molten steel and the nucleation rate. Furthermore, the vortex-shedding behavior of the upper recirculation alleviated the remelting of equiaxed crystals during the sedimentation. The behavior of multiphase flow under alternate SEMS is a novel finding. These preliminary results are encouraging and should be validated in other continuous casting processes. [ABSTRACT FROM AUTHOR]

Hollow granular mold flux is an essential functional material in the continuous casting process, and its melting behavior significantly influences continuous casting. The existing research mainly focuses on the influence of the characteristics of mold flux on the melting behavior and does not involve the operation of mold flux. This study explored the effect of flux layer thickness on the melting behavior of mold fluxes using a melting rate test method based on a copper bath and numerical simulation. The results show that with the increase in the flux layer thickness, the melting rate of mold fluxes shows the trend of the 'M curve,' including two upward and two downward stages. The 'M curve' is related to the temperature and combustion behavior of carbonaceous materials in the flux layer. In the first stage, as the thickness increases, the thermal insulation of the flux layer is significantly improved, which promotes the melting of the mold flux. In the second stage, the increase in flux layer thickness hinders the diffusion of O2 from the air to the flux layer, and the carbon–oxygen reaction rate decreases, which is not conducive to the combustion of carbonaceous materials and the flux melting. In the third stage, the increase in the flux layer thickness hinders the diffusion of CO2 to the outside, increases the CO2 concentration in the flux layer, promotes the Boudouard reaction, and increases the melting rate. In the fourth stage, with the increase in the flux layer thickness, O2 can only diffuse to the low-temperature zone (< 400 °C) of the flux layer and cannot participate in the carbon–oxygen reaction and form CO2, which decreases the rate of Boudouard reaction and the melting rate of mold flux. [ABSTRACT FROM AUTHOR]

The mold electromagnetic stirring technology and mold feeding steel strip technology are both effective method of reducing center segregation and shrinkage cavities in continuous casting bloom. In this work, a bidirectional flow-solid coupling model was established to investigate the swing and depth of steel strip feeding with the influence of both molten steel and electromagnetic forces. The results indicate that increasing the strip's feeding speed from 0.2 to 0.4 m/s without electromagnetic stirring results in an increase in the swinging amplitude from 6.26 to 11.89 mm. With the implementation of mold electromagnetic stirring, the bottom of the steel strip moves on the "Z" shape periodically, and the swing amplitude increasing with the current strength rising. When the feeding speeds are 0.2, 0.3, and 0.4 m/s, and the current is increased from 200 to 300 A, the maximum swing amplitude of the steel strip increases from 7.30, 12.18, and 21.09 to 10.34, 19.47, and 41.14 mm, respectively. [ABSTRACT FROM AUTHOR]

A new two-way coupled magnetohydrodynamic (MHD) model considering the dynamics change of electromagnetic force at steel–slag interface was established to investigate the multiphase flow and slag entrapment in slab continuous casting under mold electromagnetic stirring (EMS). The transient turbulent flow and the steel–slag interface behavior were described by solving the large eddy simulation (LES) model and volume of fluid (VOF) model. The level fluctuation, the location, and net mass of slag entrapment were quantitatively evaluated. By comparing the predicted level height within the in-situ measurement, the results show that the two-way coupled MHD model can better reveal the multiphase flow under EMS. The type of slag entrapment is closely related to the flow pattern, the vortex formation is predominant under the lower EMS current, while it changes to the shear-layer instability under the relatively high EMS current, the proportion of vortex formation slag entrapment decreases to 30.7 pct under the EMS current is 600 A. The tendency of net slag entrapment rate is the same as that of level fluctuation, with the increase of EMS current and casting speed, both the level height and net slag entrapment rate decrease firstly and then increase. Therefore, it is necessary to match the casting speed and EMS current to avoid the slag entrapment in actual production. The net slag entrapment rate is 0.034 kg/s, under the condition of 1.2 m/min casting speed and 600 A EMS current. [ABSTRACT FROM AUTHOR]

Machine learning (ML) algorithms have been proven to be effective methods in steel design and production processes. In this study, the feature analysis and prediction of slag entrapment in continuous casting process were carried out based on XGBoost model. Results show that the area under the curve (AUC) and accuracy of BO-XGBoost are 0.811 and 0.756, respectively, which are higher than PSO-XGBoost and GA-XGBoost. Feature analysis shows that mold flux, oscillation frequency, serial number, inner arc, casting speed (CS) and slab width are the key features which affect the entrapped slag defect, based on Gini coefficient and SHAP values. In addition, partial dependence plots of SHAP value suggest that it is conducive to product the qualified slabs with less entrapped slag defect, when the oscillation frequency is 60–140 cpm, inner arc is 7.5–9.5 m, CS is 0.35–1.2 m/min, serial number is less than 5, slab width is less than 1300 mm and 2# mold flux. [ABSTRACT FROM AUTHOR]

In this study, we developed a numerical model of a slab continuous casting mold coupled with multi-phase and multi-physical fields, known as MPF-Mold, and explored the effect of Fc-Mold on fluid flow, heat transfer, and solidification in the mold. Firstly, the simulation results were carefully verified from five perspectives. Next, the fast Fourier transform (FFT) is introduced to discuss the difference between MPF-Mold and the model considering only the fluid flow in the simulation results of level fluctuation. Typically, mold oscillation can be disregarded when analyzing the degree of level fluctuation through numerical simulation. However, neglecting multi-phase heat transfer and solidification may lead to overestimations of the severity of level fluctuation, especially in the region near the narrow meniscus. When coupling MPF-Mold with Fc-Mold, the upper backflow in the mold becomes stable, increasing symmetry and reducing level fluctuation severity and abnormalities. The shell uniformity index on the wide face meniscus and the lower part of the narrow face in the mold is significantly improved. This suggests that the upper and lower magnetic poles of Fc-Mold are beneficial to the shell uniform growth of the wide face meniscus and lower part of the narrow face, respectively. However, a new 'concave' appears in the shell near the corner of the mold, as a result of the horizontal vortex caused by deviations in the jet flow. Therefore, the magnetic field needs to be optimized to stabilize the flow field. MPF-Mold demonstrates advantages in achieving a reasonable match of steel grade, equipment, and process, and contributing to the digital transformation of continuous casting. [ABSTRACT FROM AUTHOR]

Longitudinal surface cracks are prevalent in the continuous casting of hypo-peritectic beam blanks, primarily related to multiphysics non-uniformity (multi-phase field, flow field, temperature field) within the mold. Therefore, multi-phase and coupled flow-thermal models were constructed to investigate the non-uniform multiphysics characteristics in the beam blank mold with a single nozzle and its effect on the formation of longitudinal cracks. First, the three-phase flow model reveals significant unevenness slag distribution along the web width, positively correlated to surface velocity of the molten steel. Subsequently, considering the impact of the solidification shell, surface velocity decreases nonlinearly with increasing immersion depth, influenced by web vortex position in the X-direction, which is also influenced by mold curvature, and interaction between web and side vortexes. Furthermore, the temperature field distribution inside the mold is non-uniform. Under the effect of the single-web recirculation flow, the temperature near the meniscus at the NN (position near the nozzle) side of the web is lower than that at the FN (position far away from the nozzle) side, resulting in more intensive initial cooling at this position. Meanwhile, a reheating zone exists at the mold exit of the NN side. Statistical analysis revealed that the absolute values of Spearman coefficient between the non-uniformity of shell thickness and the temperature and flow velocity of the molten steel exceed 0.6, which is related to the depth of the web vortex. Finally, from the perspective of the influence of SEN's immersion depth on multiphysics, the high surface velocity of the steel, strong cooling near the meniscus, and non-uniform shell thickness at the mold exit can be relieved with an immersion depth of 75 mm. The plant experiment confirmed that increasing the immersion depth from 65 to 75 mm leads to a relative reduction of 39 and 43 pct in the longitudinal cracks ratio for strands and rolled products, respectively. [ABSTRACT FROM AUTHOR]

This manuscript presents a model of a system implementing individual stages of production for long steel products resulting from rolling. The system encompasses the order registration stage, followed by production planning based on information about the billet inventory status, then offers the possibility of scheduling orders for the melt shop in the form of melt sequences, manages technological knowledge regarding the principles of sequencing, and utilizes machine learning and optimization methods in melt sequencing. Subsequently, production according to the implemented plan is monitored using IoT and vision tracking systems for ladle tracking. During monitoring, predictions of energy demand and energy consumption in LMS processes are made concurrently, as well as predictions of metal overheating at the CST station. The system includes production optimization at two levels: optimization of the heat sequence and at the production level through the prediction of heating time. Optimization models and machine learning tools, including mainly neural networks, are utilized. The system described includes key components: optimization models for sequencing heats using Ant Colony Optimization (ACO) algorithms and neural network-based prediction models for power-on time. The manuscript mainly focuses on process modeling issues rather than implementation or deployment details. Machine learning models have significantly improved process efficiency and quality; the optimization of planning has reduced sequencing plan execution time; and power-on time prediction models estimate the main ladle heating time with 97% precision, enabling precise production control and reducing overheating. The system serves as an example of implementing the concept of a cyber–physical system. [ABSTRACT FROM AUTHOR]

TiN and Ti(C,N) are the main precipitates in Ti micro-alloyed steel during the continuous casting, which directly affect the microstructure and property of the slab. However, due to the solute segregation and the different cooling rates at different locations of the slab section, it is challenging to accurately predict the precipitation behavior of carbonitride during the continuous casting process using the existing thermodynamic model. Taking into account the solute segregation laws at the solid-liquid interface during continuous casting solidification and incorporating the influence of precipitates on solute segregation, this study proposes a model for coupled carbonitride precipitation and solute segregation by introducing dynamic solute partition coefficients. Based on this, a kinetic model is established to describe growth of TiN and Ti(C,N) precipitates during continuous cooling of the slab by utilizing the micro-element superposition method. The nano carbonitride will precipitate in the solid phase upon complete solidification of the slab. The macroscopic solute distribution at different positions of the slab, ranging from the center to the surface, was calculated using a segregation model that incorporates a convective coefficient. Through this, a precipitation model for nano-carbonitrides in Ti microalloyed steel is developed by incorporating the classical nucleation theory. The models are validated by comparing the predicted values of Ti carbonitride precipitation quantity and average precipitate size with experimental data at typical locations, including the surface, 1/4 position, and internal regions of the slab. The accuracy of the predictions reaches over 90 pct. This study enhances the comprehension of precipitation and growth mechanisms of carbonitride in Ti microalloyed steel, contributing to a more comprehensive understanding of this material system. [ABSTRACT FROM AUTHOR]

The growing use of aluminum and its compounds has increased the volume of aluminum waste. To mitigate environmental impacts and cut down on manufacturing expenses, extensive investigations have recently been undertaken to recycle aluminum compounds. This paper outlines the outcomes of a study on fabricating standard EN AW-2007 alloy using industrial and secondary scrap through continuous casting. The resultant recycled bars were analyzed for their chemical makeup and examined for microstructural features in both the cast and T4 states, undergoing mechanical property evaluations. The study identified several phases in the cast form through LM, SEM + EDS, and XRD techniques: Al7Cu2Fe, θ-Al2Cu, β-Mg2Si, Q-Al4Cu2Mg8Si7, and α-Al15(FeMn)3 (SiCu)2, along with Pb particles. Most primary intermetallic precipitates such as θ-Al2Cu, β-Mg2Si, and Q-Al4Cu2Mg8Si7 dissolved into the α-Al solid solution during the solution heat treatment. In the subsequent natural aging process, the θ-Al2Cu phase predominantly emerged as a finely dispersed hardening phase. The peak hardness achieved in the EN AW-2007 alloy was 124.8 HB, following a solution heat treatment at 500 °C and aging at 25 °C for 80 h. The static tensile test assessed the mechanical and ductility properties of the EN AW-2007 alloy in both the cast and T4 heat-treated states. Superior strength parameters were achieved after solution heat treatment at 500 °C for 6 h, followed by water quenching and natural aging at 25 °C/9 h, with a tensile strength of 435.0 MPa, a yield strength of 240.5 MPa, and an appreciable elongation of 18.1% at break. The findings demonstrate the feasibility of producing defect-free EN AW-2007 alloy ingots with excellent mechanical properties from recycled scrap using the continuous casting technique. [ABSTRACT FROM AUTHOR]

To successfully prepare bulk metallic glass (BMG) slab with high efficiency and low cost, a new horizontal continuous casting (HCC) process was designed to produce 5-mm thick Zr41.2Ti 13.8Cu12.5Ni10.0Be22.5 (Vit1) amorphous alloy slab. A mathematical model was established based on finite volume method (FVM) to study the temperature field during the HCC process, when the casting temperature was 1123 K and the casting speed was 21 mm/s. The simulation results indicated that a 5 mm thick amorphous alloy slab could be successfully prepared by the new HCC process. Simulated and experimental cooling curves exhibit the same variation trend, which verifies the accuracy of the FVM model. The experimental results showed that Vit1 amorphous alloy slab with thickness of 5 mm was successfully prepared by the new HCC process. The critical thickness of the amorphous alloy slab prepared by the HCC process was further simulated. Theoretically, the maximum thickness of BMG slab cast by the HCC process is 9 mm under the continuous casting parameters. [ABSTRACT FROM AUTHOR]

The research results presented in the article constitute the next stage of a planned series of experiments on the process of refining steel from a dispersive non-metallic phase by its filtration method. The paper presents the results of experiments carried out using an innovative design of multi-hole ceramic filters, the filter holes of which have an elliptical shape. Analyses of the macro and microstructure and purity of the steel before and after the filtration process reflect the course of the research and confirm that this can be an effective and cheap method of its refining from non-metallic inclusions. The results presented are the first of their kind in the world and confirm that the shape of the filter holes of multi-hole ceramic filters may have a significant impact on the efficiency of the steel filtration process. The non-metallic phase identified at the ceramic filter-steel interface corresponds to the reaction products of the deoxidation of aluminum steel. [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]

Ductile iron with different Ni contents (0–10%) was successfully fabricated through horizontal continuous casting technology, and the effects of Ni content on ductile iron's microstructure and mechanical properties were investigated. The results showed that the Ni addition affected the diffusion of carbon atoms, altering the phase constituents during solid-state transformation. The ductile iron with Ni amounts less than 2% was composed of spheroidal graphite and ferrite. The addition of the 2% Ni addition led to more than 40% pearlite in the matrix. When the Ni content exceeded 6%, bainite and martensite were detected, which enhanced strength significantly but deteriorated ductility. Annealing treatment facilitated the dissolution of carbides and increased ferrite fraction, contributing to the improvement of ductility. The as-annealed sample with 8% Ni showed an ultimate tensile strength of 1057 MPa and an elongation of 4.6%. [ABSTRACT FROM AUTHOR]

The limited mechanical properties of pure Zn, such as its low strength and ductility, hinder its application as a material for biodegradable implants. Addressing this challenge, the current study focuses on the development of biodegradable Zn-based alloys, employing innovative alloy design and processing strategies. Here, alloys with compositions ranging from 0.02 to 0.10 weight percent (wt%) Cu, 1.22 to 1.80 wt% Ti, and 0.04 to 0.06 wt% Mo were produced utilizing a high-throughput gradient continuous casting process. This study highlights three specific alloys: Zn 1.82 Cu 0.10 Ti 0.05 Mo (HR8), Zn 0.08 Cu 1.86 Ti 0 Mo (HR7), and Zn 1.26 Cu 0.13 Ti 0.06 Mo (HR6), which were extensively evaluated for their microstructure, mechanical properties, electrochemical performance, potential as bioimplants, and cytotoxicity. These alloys were found to exhibit enhanced mechanical strength, optimal degradation rates, and superior biocompatibility, evidenced by in-vivo experiments with SD rats, positioning them as promising candidates for medical implants. This research not only introduces a significant advancement in biodegradable alloy development but also proposes an efficient method for their production, marking a pivotal step forward in biomedical engineering. The limited mechanical properties of pure Zn have hindered its application in biodegradable implants. Our research primarily focuses on the alloy design and process strategies of biodegradable Zn-based alloys. We explore the Zn Cu x Ti x Mo x alloys. This study introduces a high-throughput experimental approach for efficient screening of multi-component alloy systems with optimal properties. The Zn Cu x Tix Mo x alloys were designed and processed through gradient continuous casting, followed by homogenization and hot rolling. Our findings indicate that the Zn 1.82 Cu 0.10 Ti 0.05 Mo alloy demonstrates superior tensile, mechanical, and corrosion properties post hot rolling. The study suggests that Zn 0.13 Cu 1.26 Ti 0.06 Mo, Zn 0.08 Cu 1.86 Ti 0 Mo, and Zn 1.82 Cu 0.10 Ti 0.05 Mo alloys hold significant potential as biodegradable materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Spinel is known to cause clogging of the submerged entry nozzle in continuous casting. The effect of basicity on the precipitation behavior of MgO·Al2O3 in Al-killed steel with w[Al] = 0.065% at 1550°C was investigated. The inclusions in steel are mainly MgO·Al2O3 spinel after slag-steel reaction, which is consistent with the thermodynamic results. The polygonal spinel transforms to nearly spherical or rod-like with the sizes smaller than 5 μm with the increase of refining-slag basicity. The number of inclusions shows little variation with basicity. In industrial production, it is often observed that spinel inclusions in molten steel are transformed into CaO-Al2O3-MgO inclusions. However, this phenomenon was not observed in this study. Two sets of experiments were conducted; therefore, the reasons behind the lack of transformation from spinel to CaO-Al2O3-MgO inclusions were elucidated. We determined that Mg in MgO·Al2O3 originated from the MgO crucible, and the [Ca] and [Mg] supplied through the steel slag reaction were insufficient to facilitate the modification of Al2O3. [ABSTRACT FROM AUTHOR]

To improve the strength of the metal while maintaining good plasticity, helical fibers are added to the metal matrix. How to form helical fiber and control its parameters in the preparation process are urgent problems to be solved in the study of helical fiber-reinforced metal matrix composites. In this paper, the continuous casting process of helical fiber-reinforced metal matrix composites was proposed. To reduce the difficulty of the experiment, the formation process of helical fiber on metal matrix and the relationship between the continuous casting process parameters and helical shape fiber parameters were studied by preparing helical carbon fiber-reinforced lead matrix composites with a low-melting-point metal matrix. The results show that this process can produce helical fiber-reinforced metal matrix composite stably and continuously, and the helical shape parameters of the composite can be controlled by changing the process parameters of continuous casting. To further improve the practical application of this process, helical carbon fiber-reinforced aluminum matrix composites were prepared. The test result in terms of mechanical property shows that the tensile strength and elongation of the composite were improved. This indicates that the reinforced phase of the helical structure of the metal matrix composite has higher strength and toughness compared with the matrix metal. [ABSTRACT FROM AUTHOR]

ŠTORE STEEL Ltd. is one of the three steel plants in Slovenia. Continuous cast 180 mm × 180 mm billets can undergo cooling to room temperature using a turnover cooling bed. They can also be cooled down under hoods or heat treated to reduce residual stresses. Additional operations of heat treatment from 36 h up to 72 h and cooling of the billets for 24 h, with limited capacities (with only two heat treatment furnaces and only six hoods), drastically influence productivity. Accordingly, the casting must be carefully planned (i.e., the main thing is casting in sequences), while the internal quality of the billets (i.e., the occurrence of inner defects) may be compromised. Also, the stock of billets can increase dramatically. As a result, it was necessary to consider the abandoning of cooling under hoods and heat treatment of billets. Based on the collected scrap data after ultrasonic examination of rolled bars, linear regression and genetic programming were used for prediction of the occurrence of inner defects. Based on modeling results, cooling under hoods and heat treatment of billets were abandoned at the casting of several steel grades. Accordingly, the casting sequences increased, and the stock of billets decreased drastically while the internal quality of the rolled bars remained the same. [ABSTRACT FROM AUTHOR]

The study investigates the effect of pulsed magnetic fields on undissolved carbides in high-carbon chromium bearing steel GCr15 billets. The billets were subjected to heat treatment at 950 °C, with a pulsed magnetic field of varying durations applied during the process. The influence of the pulsed magnetic field on the distribution of undissolved carbides within the billets was investigated, and the thermodynamic and kinetic mechanisms of undissolved carbides dissolution were explored. The results indicate that the area percentage of undissolved carbides in the microstructure decreases from 1.68% to 0.06% after applying a pulsed magnetic field for 10 min, and the size of undissolved carbides decreases from 17.5 μm to 4.9 μm. When a pulsed magnetic field is applied for 30 min, all undissolved carbides dissolve. The statistics demonstrate that the average size of undissolved carbides is reduced from 14.19 μm to 0.63 μm, with a reduction percentage reaching 96%. Over the same duration, the number density of the undissolved carbides decreases from (0.19~0.55)/mm2 to (0.03~0.1)/mm2, and the percentage area of the undissolved carbides decreases from (1.26~1.68)% to (0~0.02)%. Thermodynamically, applying a pulsed magnetic field lowers the dissolution energy barrier of undissolved carbides and modifies their transformation temperature. Kinetically, the rate of alloy element diffusion is enhanced by increasing the frequency of atomic jumps. This research aims to provide new insights into enhancing the contact fatigue life of bearing steel, increasing the proportion of special steel, and optimizing the steel deep-processing process. [ABSTRACT FROM AUTHOR]

Submerged entry nozzle (SEN) clogging will affect the production efficiency and product quality in the continuous casting process. In this work, the transient SEN clogging model is developed by coupling the porous media model defined by the user-defined function (UDF) and the discrete phase model (DPM). The effects of the transient SEN clogging process on the flow field, the distribution of argon gas bubbles and the fluctuation of the interface between steel and slag in the concave bottom SEN in the continuous casting slab mold with a cross-section of 1500 mm × 230 mm are studied by coupling transient SEN clogging model, DPM and volume of fluid (VOF) model. The results show that the actual morphology and thicknesses of SEN clogging are in good agreement with the numerical simulation results. The measurement result of the surface velocity is consistent with the numerical simulation result. With increasing the simulation time, the degree of SEN clogging increases. The flow velocities of molten steel flowing from the outlet of the side hole increase, because the flow space is occupied with the clogging inclusions, which leads to the increased number of argon gas bubbles near the narrow wall. The steel–slag interface fluctuation near the narrow walls also increases, resulting in the increased risk of slag entrapment. [ABSTRACT FROM AUTHOR]

Economic limitations often hinder the extensive use of fiber-reinforced concrete in full-scale structures. Addressing this, the present study explored localized reinforcement at critical interfaces, deploying a novel synchronized casting mold that deviates from segmented casting interface studies. The research prioritized the flexural, compressive, and shear characteristics at the interface between fiber-reinforced concrete and ordinary concrete with continuous casting. The results demonstrated that polyethylene (PE) fibers significantly enhance anti-cracking capabilities, surpassing steel fibers in all mechanical tests. PE fibers' high modulus of elasticity and tensile strength considerably augmented the interface's bending resistance, facilitating better load transfer and capitalizing on the fibers' tensile properties. Additionally, their low density and greater dispersion negated the sinking behavior typical of steel fibers, thereby strengthening the compressive capacity of the interface. Although a 0.75% PE fiber volume is ideal for ductility, volumes as low as 0.25% or 0.5% are economically viable if dispersion is optimal. Conversely, steel fibers, prone to sinking and clustering, offer inferior shear resistance at the interface than PE fibers, marking a significant finding for structural applications. [ABSTRACT FROM AUTHOR]

This work conducted an exploring study to minimize porosity cavities in a 300 mm × 2000 mm slab by mechanical heavy reduction when it has solidified. Real density measurements of slab samples indicated that, with a heavy reduction of 20 mm to slab after behind its solidification end, slab center was much denser and much more consistent. Porosity volumes at 1/4 and 1/2 width regions of slab were minimized from 5.19 × 10−4 cm3/g to 1.29 × 10−4 cm3/g and from 2.27 × 10−4 cm3/g to 1.05 × 10−4 cm3/g, respectively. Original Position Statistical-Distribution Analysis (OPA) of larger sampled slabs indicated that the heavy reduction was efficiently penetrated from slab surface into center to heal porosity cavities. Obtained results indicated positive influences of heavy reduction in healing porosity holes in slab even after solidification, when the temperature gradient of slab surface and center was about 280 °C. [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]

To realize the double-roll thin strip continuous casting process for the production of high-quality steels, it is necessary to seek a new type of refractory material tailored for delivery device employed in this process. Therefore, the present study aimed to design and prepare MgAl 2 O 4 –C refractories for this purpose as well as to study their physical and mechanical properties, thermal shock resistance, oxidation kinetics, and to perform molten steel experiments after pre-oxidation treatment. The results of the present study demonstrated that the specimens could maintain high mechanical and thermal shock properties even after pre-oxidation treatment. After pre-oxidation at 1100 °C/1 h, the cold compressive strength of the specimen reached 17.63 MPa, with a residual strength ratio (thermal shock resistance) of 77.99%. Analysis of oxidation kinetics based on the shrinking core model indicated an increase in the effective diffusion coefficient and complete oxidation time with higher pre-oxidation temperature. Pre-oxidation of MgAl 2 O 4 –C refractories has been shown to be effective in reducing carbon penetration into the molten steel from carbon-containing refractories, thus maintaining the stability of the molten steel composition. This effect was attributed to enhanced contact and wettability between the steel and refractories, an augmented thickness of the pre-oxidized decarburized layer, the formation of a dense magnesium oxide layer, and the emergence of the MgAl 1·9 Fe 1 O 4 phase. Consequently, an MgAl 2 O 4 –C refractories designed for the delivery device was proposed along with anticipated applicability in the double-roll continuous casting process. [ABSTRACT FROM AUTHOR]

The article compares the efficiency of technologies for feeding liquid metal into the mold of a continuous casting machine (CCM) and its flow within the mold volume under conditions of free and forced mixing. The influence of various designs of the developed mixing devices on the nature of the melt flow in the mold volume is analyzed. The objects of research are the hydrodynamic and thermal flows of liquid metal during the casting of steel into the CCM mold. [ABSTRACT FROM AUTHOR]

Ag-Sn-In-Ni-Te alloy ingots were produced through a heating–cooling combined mold continuous casting technique; they were then drawn into wires. However, during the drawing process, the alloy wires tended to harden, making further diameter reduction challenging. To overcome this, heat treatment was necessary to soften the previously drawn wires. The study investigated how variations in heat treatment temperature and holding time affected the microstructure, microhardness and corrosion resistance of the alloy wires. The results indicate that the alloy wires subjected to heat treatment at 700 °C for 2 h not only exhibited a uniform microstructure distribution, but also demonstrated low microhardness and excellent corrosion resistance. [ABSTRACT FROM AUTHOR]

Secondary cooling electromagnetic stirring (S-EMS) significantly impacts the internal quality of continuous casting slabs. In order to investigate the effects of S-EMS modes on segregation in slabs, a three-dimensional numerical model of the full-scale flow field, solidification, and mass transfer was established. A comparative analysis was conducted between continuous electromagnetic stirring and alternate stirring modes regarding their impacts on steel flow, solidification, and carbon segregation. The results indicated that adopting the alternate stirring mode was more advantageous for achieving uniform flow fields and reducing the disparity in solidification endpoints, thus mitigating carbon segregation. Specifically, the central carbon segregation index under continuous stirring at 320 A was 1.236, with an average of 1.247, while under alternate stirring, the central carbon segregation index decreased to 1.222 with an average of 1.227. [ABSTRACT FROM AUTHOR]

The regulation of hydrogen content in the continuous casting process is conducive to the reduction of pore defects in the casting billet. In this paper, the influence of negative pressure (NP) and continuous casting speed (CCS) on hydrogen content in copper rod billet prepared by negative pressure continuous casting (NPCC) technique was analyzed, and the mechanism of the coordinated coupling of NP and melt flow on hydrogen removal was revealed. It is clarified that with the CCS of 20 mm min−1 and an increase in the NP value from − 20 to − 80 kPa, the hydrogen content is reduced from 1.0 to 0.3 ppm. The coordinated action of NP and melt flow induced by CCS can minimize the hydrogen content. When the NP value is − 80 kPa and the CCS is 10 mm min−1, the hydrogen content is as low as 0.2 ppm, and the hydrogen removal rate is 85.7%. The larger the NP, the smaller the critical nucleation radius of the hydrogen bubble, and the larger the growth rate of the hydrogen bubble. The coupling of the NP field and flow field can make the melt which is difficult to nucleate and grow of the hydrogen bubble flow to the position which is easy to nucleate and grow. The effect of the vortex fields in the purification chamber on the removal of hydrogen is not affected by the CCS, but the CCS affects the floating of hydrogen at the solidification front, which leads to a small increase in the hydrogen content with the increase of the CCS. Our study provides a theoretical basis for the preparation of high-quality metal billets. [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]

The formation of edge or surface cracks on continuous cast slabs is a significant problem as these increase the slab processing cost and affect the quality of hot/cold rolled coils. The edge crack formation is greatly influenced by slab composition, caster operation and machine maintenance strategies. The manganese-to-sulfur (Mn/S) ratio of low carbon steels has a significant effect on the formation of edge cracks. The effect of Mn/S ratio on hot ductility and edge crack tendency was investigated for low carbon boron steel over a temperature of 600–1100 °C using a Gleeble thermomechanical simulator. The temperature range of low ductility is a strong function of the Mn/S ratio, and this range decreases with an increase in Mn/S ratio. The underlying mechanism for low ductility is discussed using fractographs and microstructure. Edge cracks on slabs of this grade can be eliminated by maintaining the Mn/S ratio greater than 36 to narrow the low ductility temperature range and ensuring the surface and corner temperature of the slab beyond the temperature range of low ductility especially during unbending. A hard or soft secondary cooling strategy is recommended to maintain the surface and corner temperature of slabs beyond the low ductility temperature range. [ABSTRACT FROM AUTHOR]