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This paper proposes a novel intelligent scheduling method based on deep reinforcement learning (DRL) to solve the multi-objective steelmaking-continuous casting (SCC) scheduling problem, under time-of-use (TOU) tariffs for the first time. The intelligent scheduling system architecture is designed, and a mathematical model is established to minimise the total sojourn time and electricity cost. To effectively reduce production costs by avoiding peak periods of electricity consumption, the 'start time' of the system is generated based on the Markov Decision Process (MDP), and heuristic scheduling rules related to power cost are used as the action space, with corresponding reward functions designed according to the characteristics of these two objectives. To satisfy the continuous casting which is a particular SCC constraint, a backward strategy is developed. Additionally, a branching duelling double deep Q-network (BD3QN) is adapted to guide action selection and avoid blind search in the iteration process, and then applied to real-time scheduling. Numerical experiments demonstrate that the proposed method outperforms comparison algorithms in terms of solution quality and CPU times by a large margin. [ABSTRACT FROM AUTHOR]

To investigate the effect of the filter device on the cleanliness of molten steel and the flow field distribution within the tundish. The tundish filters were designed into five groups of pores with 20°, 25°, 30°, 35° and 40° elevation angles, and the flow field distribution and impurity removal rate of molten steel were calculated by Discrete Phase Model (DPM). The results showed that the removal rate of impurity in the molten steel could be significantly improved by using the tundish filter with elevation angle. When the elevation angle of the filter was 40°, the impurity removal rate reached 74.05%, and the flow field distribution would be more stable. The presence of the tundish filter caused the higher flow density of the molten steel before the filter inlet to decrease and become steadier after the filter, thereby enhancing the contact rate between impurities in the molten steel and the covering agent, ultimately achieving the highest impurity removal rate. [ABSTRACT FROM AUTHOR]

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]

In the process of continuous casting, the movement of inclusions plays a pivotal role in determining the grade of the final steel product. The present study focuses on the dynamic behavior of inclusions within the mold during continuous casting in the presence of a novel-designed hexa-furcated nozzle (HFN). Simulations were conducted to investigate the interaction between inclusion movement with casting speed and submerged entry nozzle depth (SEN), specifically focusing on the effects of the HFN. Using a water model validation approach, the study simulated the movement of inclusions under various casting conditions, replicating real-world scenarios encountered in steel production. The experiments revealed significant insights into how the introduction of the HFN influences the behavior of inclusions within the mold, shedding light on potential strategies for optimizing casting parameters to diminish inclusion shortcomings in the final steel product. [ABSTRACT FROM AUTHOR]

The objective of this paper is to present the effect of horizontal continuous casting parameters on macrosegregation and its effect on microstructures, textures, mechanical properties, and electrical resistivity of Cu–Mg alloy rod. By increasing the pulling distance and intermittent extraction time, chemical macrosegregation was observed along the longitudinal section of the cast rod, which reached a distance of 40 mm. Three areas were identified along the length of the material, especially at high pulling distance: with decreasing, quasi-stable, and increasing Mg concentration area. As the pulling distance increased, the difference in the observed extreme values of Mg concentration increased. Two distinct zones of different grain size were also observed. The first zone was formed of large columnar grains with a preferred direction of solidification ⟨ 100 ⟩ inclined to the axis of the wire, followed by a second zone formed of small grains of random texture. Consequently, difference in resistivity occurred from one zone to another and the resistivity increased from 37.5 to 41 nΩm. Likewise, the hardness varied between the values of 90 up and 110 Hv. The most homogenous chemical composition was obtained with up to 6 mm of pulling distance and up to 3 seconds of intermittent extraction time. [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 heat distribution and wear threat of the plate crystallizer used in continuous casting production are different in each area, and a single-thickness coating is unable to fulfill the requirements of all areas. To extend the service life of the crystallizer, a high hardness WC-Cr3C2-Ni thickness gradient wear-resistant coating was prepared on the inner wall of the crystallizer via the HVAF (High-Velocity Air Fuel) spraying technology. In cyclic thermal shock environments, the thermal shock resistance of planar coatings decreased with the thickness. The coating with a thickness of 100 μm exhibited the best thermal shock resistance, with up to 25 cycles at 800 °C thermal shock. In high-temperature wear experiments simulating actual service environments, the 300 μm coating, which owned the worst theoretical thermal shock resistance, was well bonded to the substrate and exhibited good serviceability. Comprehensive experimental results showed that the WC-Cr3C2-Ni coatings deposited by HVAF were stable in practical long-cycle production. The coating preparation process proposed in this paper has been applied in domestic steel mills, effectively extending the working cycle of the production line and improving economic efficiency. This study will provide a theoretical basis for the selection and preparation of surface coatings for continuous casting crystallizers and other structures in complex service environments. [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]

Copyright of Foundry Technology (1000-8365) is the property of Foundry Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Foundry Technology (1000-8365) is the property of Foundry Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Fe-15Mn-10Cr-8Ni-4Si alloy, which has excellent low-cycle fatigue durability, was developed as a core material for steel-based vibration dampers that are effective against large-amplitude, long-period earthquake motions, and was put into practical use in 2014. However, manufacturing using small-scale equipment was expensive, so the authors tried manufacturing using stainless steel continuous casting facility and rolling facility, and succeeded in mass production. The authors also developed welding materials and welding techniques to assemble a buckling restraint brace damper with flat plasticizing section and one with cruciform plasticizing section, and successfully put these two types of brace dampers into practical use. The alloy plate has been recognized as an industrial product that can be manufactured with stable quality, and has been approved by the Minister of Land, Infrastructure, Transport and Tourism as a steel material for construction. [ABSTRACT FROM AUTHOR]

Copyright of Metal Working (1674-165X) is the property of Metal Working Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The flow field, fluctuation of interface between steel and slag, distribution and capture of argon gas and solidified shell thickness in molds with different nozzles with two or three holes are studied with high-temperature quantitative velocity measurement and numerical simulation. The simulated results of surface velocities are in good agreement with the high temperature measurement results under different argon gas flow rates in the mold with the two- and three-hole nozzles. Compared to the mold with the three-hole nozzle, in the mold with the two-hole nozzle, the surface velocities of molten steel, fluctuation of interface between steel and slag, and inclination angles of jet flow of molten steel are larger, while the capture ratio of argon gas bubbles and solidified shell thickness are smaller under the same continuous casting parameters. When the argon gas flow rate is increased from 4 L/min to 8 L/min, the inclination angle of jet flow and capture ratio of argon gas decrease from 21.8° to 16.7° and increase from 0.12% to 0.27% in the mold with the two-hole nozzle. Those decrease from 20.5° to 11.3° and increase from 0.44% to 0.49% in the mold with the three-hole nozzle, respectively. [ABSTRACT FROM AUTHOR]

Fe-Mn-Al-C high-manganese and high-aluminum (high-Mn and high-Al) steel has the characteristics of high strength at room temperature and low temperature, good fatigue performance, high elongation, and good energy absorption in collisions. It is a lightweight advanced steel material with great potential for structural parts in automobile, transportation, military, and other fields. At present, there are serious surface quality defects and drastic slag–metal reactions during the continuous casting production, which hinder the efficient production of high-Mn and high-Al steel. The paper focuses on the development and challenges of continuous casting of high-Mn and high-Al steel. Firstly, the current development status of high-Mn and high-Al steel is reviewed. Then, combined with the production practice of continuous casting, difficulties and key points of control of high-Mn and high-Al steel are introduced from three aspects of non-metallic inclusion control, casting superheat control, and cooling process control. Finally, the challenges currently encountered in the production different types of mold fluxes are summarized and analyzed, and the key points for the development and application of a new type of titanium-containing continuous casting mold flux for high-Mn and high-Al steel are discussed. It is expected to provide a useful reference for improving the quality of Fe-Mn-Al-C high-Mn and high-Al steel for automotive and realizing its efficient and large-scale continuous casting production as soon as possible. [ABSTRACT FROM AUTHOR]

The solidification structure and segregation behavior in 20Mn2 alloyed steel from continuously cast billet with different casting speed (2.0, 2.4, 2.7 m/min) has been investigated, and the dendrite evolution and solute enrichment characteristics in the billet at high speed casting has been revealed. It is found that the deflection angle in the columnar dendrite induced by M-EMS decreases as withdraw speed increases, mainly due to the decrease in the average stay time in the stirring zone instead of the increase of steel flow rate, indicating the effect of M-EMS on the homogeneity of temperature and promotion of free nucleus formation reduces. The equiaxed ratio in the billet increases as casting speed increases from 2.4 to 2.7 m/min, attributed to the F-EMS acting as S-EMS to stimulate the formation of nucleus. The alignment of equiaxed zone in the case of 2.4 and 2.7 m/min is much better than that in 2.0 m/min, due to the weakening effect of M-EMS and strengthening effect of early F-EMS, together with the increase of superheat. The center segregation in the billet shows no obvious change as casting speed increases from 2.0 to 2.4 and 2.7 m/min, and low superheat, appropriate F-EMS and F-EMS working as S-EMS is the explanation for different trials respectively. The spot segregation in the billet deteriorates as casting speed increases, involving the increase in the size, number and solute content. The most severe solute enrichment is in the vicinity zone where fine dendrite and coarse dendrite contact. The countermeasures to improve the center quality of continuously cast billet at high speed is proposed. Medium superheat, strengthened M-EMS, intense secondary cooling, appropriate S-EMS and F-EMS are beneficial for most steels. [ABSTRACT FROM AUTHOR]

In the process of continuous casting, the slab temperature is a particularly crucial production parameter. However, it is still being monitored on the surface of the slab. At present, the prediction of slab temperature using machine learning models is not feasible due to the lack of internal temperature data from actual production. In this paper, a prediction method based on DNNs algorithm integrating numerical simulation and SHAP analysis is proposed to monitor the temperature field of continuous casting slab in real-time. The dataset comprises 6 input features and 5 output features. Following data preprocessing, four distinct machine learning models were developed employing DNNs, SVM, XGBoost, RF algorithms to individually predict the temperature of the slab. The DNNs model is selected as the optimal model according to the performance comparison using performance parameters such as MAE, MSE, and R2. SHAP value is calculated for the sensitivity analysis of the influence of the characteristic parameters of DNNs prediction model on the prediction results. The experimental results indicate that the prediction model has an average success rate of 96.48 pct within a temperature accuracy of ± 20 °C. Moreover, the resident time, the amount of internal side water within the slab, and the internal side heat transfer coefficient of the slab have the most significant impact on the model. This study introduces a novel method for establishing machine learning models with machine learning techniques. [ABSTRACT FROM AUTHOR]

The stable control of mold level is a key link in the production of high-quality continuous casting slabs. Periodic mold level fluctuation (PMLF) is common during the continuous casting process, and the abnormal PMLF has significant harmful effects on surface quality of slab. This article proposed an analysis and control method for abnormal PMLF. First, the finite impulse response (FIR) filter and fast Fourier transform (FFT) were used to remove noise interference in PMLF data and highlight the fluctuation characteristics of PMLM. Then, considering that uneven solidification has a significant impact on abnormal PMLF, the influence of chemical composition on the equilibrium Fe-C pseudo-binary diagram was calculated by Thermo-Calc software. Furthermore, roller diameter, roller spacing, casting speed, and chemical composition were chosen as the prediction indicator to predict the quality of PMLF. Random forest (RF) model shows good performance in predicting PMLF; the prediction accuracy of RF model is 92.76 pct, which is 21.39 pct higher than that of GA-BP model. Finally, the Feedforward fuzzy PID (F2FPID) controller designed in this article was used to eliminate abnormal PMLF. The average range of mold level fluctuation under the PID controller is ± 6.8 mm, while under the F2FPID controller, the average range of mold level fluctuation is ± 1.1 mm. And the F2FPID controller owns a lower overshoot of 0.48 pct and an adjusting time of 1.52 seconds, which are 94.8 pct and 59.5 pct, respectively, lower than those of the PID controller. [ABSTRACT FROM AUTHOR]

To avoid coarse crystallization of CaO–SiO2–Al2O3 inclusions during the solidification stage of continuous casting process, the effect of MgO on crystallization behavior of these inclusions is investigated. The single hot thermocouple technology experiment results show that the low melting point CaO–SiO2–Al2O3 inclusions do not easily crystallize during the solidification stage. However, with increasing the MgO content from 4.5 to 15.7 wt pct, the initial crystallization temperature of inclusions increases from 1376 K to 1431 K (1103 °C to 1158 °C) and the crystallization ratio increases from 35.45 to 100 pct. The crystallization ability of the inclusions can be predicted by the initial crystallization potential and the viscosity at the melting point. With increasing the MgO content from 0 to 15.7 wt pct, the initial crystallization potential of the inclusions increases from 0.28 to 0.87 and the viscosity of the inclusions at the melting point decreases from 4.47 to 0.56 Pa s. The higher the initial crystallization potential and the lower the viscosity near the melting point, the easier the crystallization of the inclusions occurs. Al2O3 mainly acts as the network former and participates in the construction of the network structure. With the increase of MgO content, the crystallization ability of inclusions increases gradually, which is mainly related to the increase of melt structure depolymerization. [ABSTRACT FROM AUTHOR]

Solidification end reduction is an effective approach to control the central porosity during continuous casting of round bloom, although it is not widely reported. In the present work, a three-dimensional finite element model has been developed with coupling heat transfer and mechanical deformation for a φ690 mm continuously cast round bloom, and verified by the surface temperature, shrinkage zone width, reduction crack location, and deformed contour shape. It is found that the contact width between roller and the bloom increases with the increase of reduction amount and approximately in a parabolic relationship. To cover the whole range of the shrinkage zone, the total reduction amount should not be smaller than 25 mm as the width of the shrinkage zone is about 120 mm. The bulge width along the horizontal direction during reduction increases as the total reduction amount increases, and the relationship can be fitted by a parabolic equation. The reduction thickness in the shrinkage zone is larger when the reduction amount is higher, and it also follows parabolic relationship. The deformation in the shrinkage zone is more obvious when the reduction is conducted before crater end. The reduction efficiency for φ690 mm round bloom before solidification is between 20 and 30 pct, while after solidification is roughly between 12 and 20 pct. It increases with the increase of apparent reduction amount, mainly related to the increase of the strain rate. The deformation of the shrinkage zone in φ690 mm round bloom with 30 mm apparent reduction in continuous casting and hot rolling has been compared. The equivalent strain in the shrinkage zone of the round bloom in continuous casting is about 0.047 to 0.052, while that in hot rolling is about 0.031 to 0.036, indicating the reduction efficiency of the former is about 1.5 times higher than the latter. [ABSTRACT FROM AUTHOR]

During steel solidification, solute element segregation at dendrite boundaries intensifies the precipitation of MnS inclusions. The morphology, dimensions, and spatial distribution of these precipitates influence the high-temperature thermoplasticity of continuously cast slabs. Variations in the equilibrium partition coefficients (ki) of different cooling phases in Q355 microalloyed steel were investigated using thermodynamic calculations. To obtain accurate parameters, the thermodynamic behavior of the continuous casting process was simulated using Marc finite element software for thermal history data at each node of the cooling process. A real-time constant cooling rate model was established, and four different rates were selected to verify the model. Model predictions and observations demonstrated strong agreement, with an error range of 2.2 to 5.2 pct. A method for calculating variable cooling rates was proposed. Based on the heat transfer model, a real-time variable cooling rate model was established and high-temperature confocal laser scanning microscopy (HT-CLSM) was used for observation of the solidification process. This prediction model can effectively characterize MnS precipitation and growth and the effects of casting speed and superheating on the particle size distribution of MnS inclusions. This study provides a rapid and accurate method for predicting MnS precipitation, helpful for optimizing the process of continuous casting. [ABSTRACT FROM AUTHOR]

The excellent water-cooling structure contributes to achieve efficient and reasonable heat transfer in the mold, which is essential for achieving the ultra-large beam blank continuous casting (ULBBCC). Therefore, this work designed different ultra-large beam blank mold (ULBBM) which were composed of three wide face copper plates with different water-cooling structures and two narrow face copper plates with different water-cooling structures, on the basis of which a three-dimensional heat transfer model of the copper plate coupling with the cooling water flow in the water-cooling structure was developed with the consideration of fluid-solid coupling interaction. Then, the accuracy of the model was verified by comparing the model-predicted and measured water temperatures. Finally, the focus is comparing the heat transfer behavior of the mold under different water-cooling structures, as well as the temperature and flow evolution of the cooling water, and the most optimal water-cooling structure was proposed. The results show that the water-cooling structure of water slots with semicircular roots (Mold II) contributes the narrow face copper plate of ULBBM to obtain excellent temperature uniformity and achieve homogenization of heat transfer. The water-cooling structure of small hole water channel with a diameter of 10 mm (Mold III) decreases the maximum temperature at the fillet of wide face copper plate of ULBBM to 582.9 K and the maximum circumferential temperature difference near the meniscus to 103.3 K, and which contributes the wide face copper plate to obtain higher temperature uniformity and lower fillet temperature, and achieve homogenization of heat transfer. [ABSTRACT FROM AUTHOR]

Based on our previously proposed three-phase solidification model, a comprehensive analysis on the impact of the only electromagnetic stirring (EMS) and combined EMS on the microscopic structure evolution and solute segregation behavior in a 500 mm diameter 42CrMo steel of continuously cast round bloom. The results indicate that M-EMS has a notable impact on expediting the dissipation of superheat, enhancing the initiation of grain formation, and enlarging the equiaxed region. The percentage of equiaxed grains increased from 59.26 to 63.37% with the increment in current intensities of M-EMS from 250 to 350 A. However, higher M-EMS current intensities were found to enhance local positive segregation in the transition zone between columnar and equiaxed grains. The impact of M-EMS on improving center positive segregation was minimal, as the ratio of center positive segregation remained consistently around 1.17. Furthermore, the implementation of F-EMS demonstrated its effectiveness in reducing center positive segregation. The ratio of center positive segregation decreased from 1.14 to 1.10, when the current intensity increases from 150 to 250 A. However, it should be noted that F-EMS alone did not contribute to the expansion of the equiaxed zone. On the other hand, when M-EMS was combined with F-EMS (referred to as combined EMS), it showed potential in mitigating center segregation during continuous casting round blooms. The benefits observed with M-EMS in terms of promoting grain nucleation and expanding the equiaxed grain zone were also evident in this combined EMS process. Furthermore, a notable enhancement in the equiaxed grain ratio up to 60.13% was observed combined EMS models were simultaneously employed during continuous casting of round blooms. And, there was a reduction in center segregation ratio for round blooms to as low as 1.09. [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]

The slag-metal reaction between traditional CaO-SiO 2 -CaF 2 -Na 2 O-based slag and high-titanium steel deteriorates the performance of the mold flux, negatively affecting the surface quality of the slab and causing issues in continuous casting. To maintain the stability of slag properties after the slag-metal interaction, BaO and Li 2 O were added to the mold flux as a potential new slag system of the BaO-CaO-SiO 2 -TiO 2 -CaF 2 -Li 2 O-Na 2 O seven-component slag for the continuous casting of high titanium steel. In this study, the effects of the BaO/CaO ratio on the structure and properties of the seven-component slag were examined using molecular dynamics simulation and Raman spectroscopy, and the effect of the BaO content on the amphoteric behavior of TiO 2 was also investigated. With the gradual substitution of CaO by BaO, the melt's basicity increases, and TiO 2 transforms from acidic TiⅤ to alkaline TiⅥ. Simultaneously, the addition of BaO promotes the conversion of O b into O f and O nb , resulting in a simplified melt structure. The continuous increase in content of structural units Q Si 0 and Q Si 1 , along with the continuous decrease in content of Q Si 3 and Q Si 4 , further elucidates this phenomenon. Hence, it can be inferred that BaO primarily functions as a depolymerizing agent within the network structure of the melt. [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]

Since most hot and cold metal-forming processes originate from various casting processes, it is important to test their susceptibility to the deformation of new materials. Cast rods of CuMg alloys with a Mg content of 2, 2.4, 2.8, 3, 3.2, 3.6, and 4 wt.% were obtained in the continuous casting process with pure copper as a reference material in order to obtain information on the material's ability to withstand 50% deformation. The materials in the as-cast state were subjected to solutioning, cold drawing, and recrystallization. After each process, samples were taken and subjected to upsetting tests with 50% deformation applied in a single operation. Additionally, materials in the as-cast state were subjected to upsetting tests at 700 °C. The hardness and electrical conductivity of each sample were analyzed. Selected samples were subjected to microstructural analysis. The obtained results show an increase in hardness from 46 HB to 90–126 HB, and a further increase to 150–190 HB with a quasi-linear decrease of electrical conductivity, which proved the influence of solid-solution and strain hardening, respectively. The microstructural analysis proved that such deformation does not cause microcracks. Furthermore, in the case of CuMg up to 3 wt.% of Mg, the alloying additive completely dissolved after solutioning. [ABSTRACT FROM AUTHOR]

5356 aluminum alloy welding wire is widely used in automotive, aerospace, and marine, due to its excellent corrosion resistance, high strength-to-weight ratio, and excellent weldability. The properties of aluminum alloys are primarily determined by their microstructure. This study investigates the microstructure evolution, mechanical properties, and texture of 5356 aluminum alloy welding wire produced using the continuous casting direct rolling (CCDR) method. The results show that continuous rolling led to an increased generation of dislocations in the matrix, and dynamic recovery plays an important role in reducing dislocation density. As a result of dynamic recovery, the microstructures of 3RPs consist of extensive deformed grains and numerous substructures. The continuous casting direct rolling textures are characterized to be cube and shear textures. After 10 rolling processes, the 5356 aluminum alloy welding wire shows a highest tensile strength of 365 MPa with a lowest elongation of 8.8%. This research provides theoretical guidance to produce high-performance 5356 aluminum alloy welding wires, paving the way for their more efficient and reliable applications. [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]

During high-speed continuous casting, the effect of secondary cooling on the quality of the billet is more obvious, and the possibility of quality problems is higher. This study takes the continuous casting machine producing 165 mm × 165 mm billet as the research object. The six different secondary cooling schemes are designed with the 4.5 m/min casting speed. By comparing the shell deformation, surface stress, surface temperature recovery, and metallurgical lengths at different secondary cooling schemes, the secondary cooling scheme applied in the high-speed continuous casting process is selected. The results show that the surface temperature recovery and stress of the billet in Scheme 1 are higher than those of other cooling schemes. The metallurgical length and shell deformation of the billet in Scheme 4 are higher than those of other cooling schemes. In Schemes 2, 3, 5, and 6, the shell deformation of Schemes 3 and 5 is higher than that of Schemes 2 and 6. In Schemes 2 and 6, the maximum surface central stress of the continuous casting billet in the secondary cooling zone is 36.3 MPa and 31 MPa, respectively. Scheme 6 is used as the secondary cooling scheme of high-speed continuous casting in this study. The water quantity in secondary cooling zone 1 ~ 5 segments of Scheme 6 is 28 m3/h, 31 m3/h, 16 m3/h, 10 m3/h, and 6 m3/h, respectively. Finally, the industrial trial is carried out, which proves that Scheme 6 can be applied to high-speed continuous casting. [ABSTRACT FROM AUTHOR]

To achieve the desired superheat of molten steel during the continuous casting process, optimization of process parameters such as molten steel temperature in ladle furnace, casting speed, and baking temperature is necessary. Therefore, obtaining the superheat corresponding to these process parameters in advance is particularly important. To address this issue, a model for predicting the temperature of molten steel in the tundish during continuous casting is designed. The model adopts a combined modeling approach of mechanistic model and data model. To address the issue of the mechanism model's inability to capture the variation of the lining's thermal parameters, this article improves the traditional physics-informed neural network (PINN) algorithm. It combines the constraints from both the forward and inverse problems, allowing for obtaining solutions to the equations while capturing the variation of equation parameters. Actual data from multiple casting sequences at a steel plant are collected to validate the accuracy and interpretability of the model. The results show that the error of the model is about 2.1k which has better accuracy compared to pure mechanistic model and pure data model. Additionally, it can capture the variation patterns of tundish lining thermal parameters under different operating conditions. Therefore, the model designed in this article can provide both profound physical interpretation ability and more practical predictions of molten steel temperature. [ABSTRACT FROM AUTHOR]

An alloyed cast iron was prepared by horizontal continuous casting. To study the salt bath temperature on microstructure and mechanical properties, the alloyed cast iron was firstly austenitized at 950 °C for 3 h and then austempered in salt bath at various temperatures (250 ℃, 300 ℃ and 350 ℃) for another 3 h. The scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), and X-ray diffraction (XRD) were employed to observe the microstructure and test the mechanical properties of the alloyed cast iron. Results show that the microstructure of the alloyed cast iron is mainly composed of acicular or feathery ferrite (bainite), retained austenite, carbide, and graphite. When austempered in salt bath at 250 ℃, 300 ℃ and 350 ℃ for 3 h, the volume fractions of retained austenite are 33.1%, 41.7%, and 57.2%, the thickness of acicular ferrite are 0.25 μm, 0.3 μm, and 0.8 μm. As the salt bath austempering temperature increases, the mechanical properties decrease due to the increase of the volume fraction of retained austenite and the thickness of acicular ferrite. The highest tensile strength of the alloyed cast iron is achieved when it is austempered at 250 ℃ in a salt bath. Under these conditions, the tensile strength of the alloyed cast iron can reach 1,429 MPa. Tensile test results indicate that the fracture mechanism is predominantly brittle fracture. [ABSTRACT FROM AUTHOR]

The continuous casting and continuous extrusion processes were used to prepare 6201 aluminum alloy wires. Electron backscattering diffraction, transmission electron microscopy, hardness, tensile, and conductivity tests were used to study the effects of Ni microalloying on the microstructure, mechanical properties, and conductivity of 6201 aluminum alloy. The results show that Ni microalloying refins the grain size of 6201 aluminum alloy in continuous casting, continuous extrusion and solid solution treatment states, which in turn improved the strength. During the aging process, Ni microalloying accelerated the age-hardening behavior of 6201 aluminum alloy, which increase the peak hardness and strength while retaining plasticity. But it decrease the electrical conductivity of the alloy because the Ni atoms always existed in the form of a solid solution, increasing the density of β"-precipitates and refined the size. The optimum yield and tensile strengths of 295. 33 MPa and 326. 12 MPa, respectively, are obtained by Ni microalloying and optimization of the heat treatment process. [ABSTRACT FROM AUTHOR]

The paper addresses the issue of early detection of steel ladle slag in the continuous casting of steel. In this study, the vibration method of slag detection was evaluated due to the high informative value of the vibration signal. The analysis is based on the variation in the character of the vibration acceleration signal of the protective tube manipulator of the continuous casting machine when slag enters the intermediate ladle. The envelope method of the vibration power spectrum was used to derive five empirical criteria for slag cut-off. In addition, these criteria included data on the molten mass in order to reduce the occurrence of false alarms. A generalized measure was developed to determine the performance quality of the criteria which was estimated to be 91.79%. This result validates the efficiency of these criteria and their suitability for testing in real production conditions. [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]