With the increasing improvement of the performance requirements for steel in high-end equipment, high titanium steel has drawn wide attention due to its high strength, toughness, wear resistance and corrosion resistance. However, new challenge has encountered in smelting and casting of high Ti steel, due to the fact that Ti shows high activity and strong affinity to react with oxygen and nitrogen to form high melting point inclusions. The general characteristic of the submerged nozzle clogging in continuous casting of high Ti steel was reviewed, and the multilayer structure and chemical composition of the clog were revealed. The submerged nozzle clogging process and mechanism during continuous casting by Ti addition was summarized, and the chemical reaction type, sequence and clog component at the interface of the continuous casting nozzle were compared between Ti containing steel (w(Ti)≤0.01%) and high Ti steel (w(Ti)>0.1%). The inner wall erosion, temperature drop and physical adhesion were regarded as the key influencing mechanisms. Finally, the effective control strategy to solve the nozzle clogging problem in high Ti steel continuous casting has been proposed, and the new achievements on Ca treatment, nozzle material design and external field implementation has been outlined particularly.

To enhance the overall performance of magnesia-carbon bricks for ladle slag lines, this study introduced light-burned ascharite powder into a conventional formulation. Its effects on the physical properties, high temperature modulus of rupture, thermal shock resistance, and slag resistance of the bricks were systematically investigated. Results demonstrate that the composite addition of light-burned ascharite and metallic aluminum powder exhibits superior high temperature modulus of rupture, slag resistance, and thermal shock resistance compared to the formulation with ascharite alone. The synergistic effect is attributed to two mechanisms. The first involves aluminum powder, which at low to medium temperatures forms Al₄C₃ fibers, subsequently oxidized to Al₂O₃ and transformed into spinel. This process effectively fills and seals pores through the associated volume expansion and solid-phase deposition, thereby improving the medium-to-high temperature strength and slag resistance. Simultaneously, an appropriate amount of light-burned ascharite powder generates a dispersed magnesium borate liquid phase at high temperature, which promotes sintering densification, alleviates thermal stress, and strengthens the matrix through pinning effect, thereby significantly enhancing the high-temperature performance and thermal shock stability.

A statistical analysis was performed on both micro-inclusions and macro-inclusions in a 31-meter-long unsteady-state transition slab from two heats (A and B) of IF steel for automotive outer panels produced at a steel plant. Analysis of micro-inclusions larger than 5 μm revealed that the number density of inclusions increases significantly and remains elevated from 1 m before to 13 m after the start of casting heat B. Typical macro-inclusions larger than 30 μm, extracted via large-sample electrolysis, mainly consist of: blocky Al₂O₃ inclusions around 250 μm, irregular blocky mold flux inclusions around 600 μm, Al₂O₃+SiO₂ inclusions generally ranging from 50 μm to 200 μm, and spherical calcium aluminate inclusions with sizes between 30 μm and 100 μm. The content of macro-inclusions rises notably and stays high from 3 m before to 14 m after the start of casting heat B. Thus, the length of the transition slab with severely compromised molten steel cleanliness is approximately 17 meters.

In order to mitigate fracture and abnormal erosion of stopper rods in continuous casting tundishes and thereby enhance production safety and stability, a comparative analysis was conducted on two commonly used slab tundish stopper rods. The study examined their internal structure, chemical composition, phase constitution, and physical properties at both room and high temperatures. The results indicate that the HN-1 stopper rod, featuring a phosphate-bonded corundum-mullite anti-adhesion coating, a tightly adherent anti-oxidation coating, and a MgAl₂O₄-C head material, demonstrates excellent oxidation and erosion resistance. However, its slag line, composed of a low-ZrO₂ Al₂O₃-C material, exhibits reduced erosion resistance, leading to fracture during operation. In contrast, the HY-1 stopper rod employs an Al₂O₃-C/MgO-C composite structure in its slag line, providing superior erosion resistance. Nevertheless, the composition design of its anti-oxidation coating and the inadequate oxidation resistance of the rod body result in uniform internal oxidation of the stopper rod. Through optimization of the slag line material for the HN-1 rod and adjustments to the glaze composition and matrix oxidation resistance for the HY-1 rod, the sequence length for continuous casting of low-carbon steel was increased from 22 heats to 27-32 heats. These improvements effectively ensured the safety and stability of the continuous casting process.

The size and distribution of bubbles play a crucial role in determining the efficiency of metallurgical processes and the quality of the resulting products. A common challenge in current practices is the formation of excessively large and poorly dispersed bubbles, which significantly restrict heat and mass transfer, reaction kinetics, and the removal of inclusions between molten metal and bubbles. This paper systematically reviews recent progress in the refinement and uniform dispersion of bubbles in metallurgical systems. Key techniques such as gas injection parameter control, forced bubble detachment, argon blowing via submerged entry nozzles, dissolved gas flotation, mechanical stirring, and high-shear methods are examined in terms of their underlying mechanisms and practical performance. The fundamental principle of bubble refinement involves enhancing turbulent flow in the liquid phase to facilitate bubble breakup and suppress coalescence. Owing to the limitations of contact-based approaches in high-temperature molten media, non-contact electromagnetic flow control has emerged as a promising alternative. By generating intense liquid turbulence through electromagnetic forces, this method enables effective bubble refinement and homogeneous dispersion, offering considerable potential for improving metal purity and process efficiency in metallurgical operations.

In the continuous casting process, the stopper rod plays a pivotal role in regulating the flow of molten steel from the tundish into the mold. Its performance has a direct impact on the stability of the molten steel levels in both the tundish and the mold, as well as the control of the flow rate from the tundish. Spinel-carbon refractory materials are extensively utilized for the stopper rod owing to their superior chemical stability and resistance to molten steel erosion. However, when casting certain steel grades with excessively high oxygen content, severe erosion was observed on the stopper rod, which even compromised normal flow control. To address this situation, an analysis of the used stopper rod was conducted, revealing that the oxygen content and calcium content in the steel, along with the density of the stopper rod, are crucial factors influencing erosion. Based on these findings, an optimization study was carried out to adjust the contents of spinel, flake graphite, and SiC in the stopper rod, aiming to enhance its mechanical properties, thermal shock resistance, oxidation resistance, and erosion resistance. Among the samples, A3 exhibited superior performance compared to the control sample A0. Under the condition of maintaining excellent thermal shock resistance, the high-temperature strength of sample A3 increased by 2.9 MPa (approximately 30%), and its oxidation resistance improved by approximately 35%. During steel plant trials, the optimized screw head A3 demonstrated remarkable application performance. Compared with the original screw head, it significantly enhanced the erosion resistance during the casting of high-oxygen steel grades.

Al₂O₃-C refractories are widely used in sliding nozzles and continuous casting components due to their excellent thermal shock resistance and corrosion resistance. However, conventional high-carbon Al₂O₃-C materials suffer from issues such as carbon pickup in molten steel and CO₂emissions due to oxidation, as well as a loose microstructure that leads to performance degradation. These problems negatively affect clean steel production, environmental protection, and the service life of the materials. Therefore, there is an urgent demand to develop low-carbon Al₂O₃-C materials. However, key properties such as thermal shock resistance and corrosion resistance are insufficient to meet application requirements with carbon reduction. Optimizing carbon sources and additives is essential for improving the performance of low-carbon Al₂O₃-C materials. The effects of different carbon sources and additives on the composition, structure and properties of low-carbon Al₂O₃-C materials are reviewed in this paper, and the potential application of biochar as a green, renewable and highly reactive carbon source is prospected. The aim is to provide new ideas for the green preparation and performance improvement of low-carbon Al₂O₃-C materials.

The flow and heat transfer state of molten steel within the slab continuous casting mold is a critical factor determining the quality of the final slab. Utilizing artificial intelligence technology to achieve real-time, precise prediction and intelligent control of this complex multiphysics field is of great significance for improving the quality of high-end steel and promoting the intelligent transformation of the steel industry. To this end, this study first established a mechanistic model of molten steel flow, heat transfer, and solidification under electromagnetic stirring (EMS) in a slab continuous casting mold. Furthermore, a set of flow field evaluation criteria for the mold was proposed—namely, a steel-slag interface slag entrapment-freezing index, a shell uniformity index, and an inclusion removal index—with the aim of optimizing the EMS process. Secondly, based on the dataset of 3D flow and temperature fields generated by the aforementioned model, a large-scale multiphysics prediction model for the mold was developed using a deep neural network (DNN) architecture, enabling rapid prediction of the multiphysics field within the mold. The results show that, compared to traditional numerical simulation results, the prediction errors of the large model for the multiphysics fields, including the flow and temperature fields within the mold, are all within 10%. Meanwhile, the model′s computational speed was significantly increased, with the average computation time to obtain the multiphysics field within the mold being drastically reduced from the original 24 hours to 2 seconds. This research provides key technical support for achieving online optimization and closed-loop control of the EMS process and for the construction of a "Digital Twin" system.

Nozzle clogging is widely present in low-carbon steel, stainless steel, rare earth steel and other steel. Numerical simulation of nozzle clogging during continuous casting can reveal the formation process of deposits and quantitatively analyze the influence of various factors on clogging. The results provide theoretical guidance for controlling and mitigating nozzle clogging. However, current simulations are performed off-line. Furthermore, numerical simulation can predict the location where clog deposits break off, the size of the broken fragments, as well as their distribution and inheritance within the cast strand. To date, researchers have developed corresponding mathematical models based on the four main formation mechanisms of nozzle clogging, and the findings have been validated through both laboratory and industrial experiments. Nevertheless, nozzle clogging incidents still occur occasionally in practice. There is currently a lack of real-time prediction methods for the evolution of clogging. Future studies on numerical simulation of nozzle clogging may focus on real-time forecasting of clogging development and prediction of the distribution of broken clog materials in the cast product.

In the context of the global "dual carbon" strategy, ultra-high speed thin slab continuous casting has become a key technology for the green transformation of the iron and steel industry, owing to its significant advantages in energy saving, emission reduction, and product quality. However, high casting speeds (6-8 m/min) lead to issues such as unstable molten steel flow and inadequate lubrication by mold flux, which hinder further development. Although electromagnetic braking (EMBr) technology can suppress molten steel turbulence through applied magnetic fields, its specific effects on mold flux properties remain unclear. This study systematically investigates the evolution of physicochemical properties of ultra-high speed thin slab mold flux under magnetic fields. The results indicate that a mold flux with a basicity (R) of 1.67, viscosity of 0.22 Pa·s, melting point of 1 042 ℃, and a Na₂O-Li₂O-F flux system exhibits excellent process adaptability, meeting the requirements of rapid melting and uniform lubrication at high casting speeds. Under a magnetic field intensity ranging from 0 to 90 mT, the crystallization behavior of the mold flux is significantly influenced: increasing magnetic field strength advances nucleation time, prolongs the crystallization interval, inhibits crystal growth, and increases solidification volume expansion by 23%. Microstructural analysis reveals that the magnetic field promotes preferential growth of the Ca_0.87Mn_0.19Mg_0.94Si₂O₆ phase, increasing its proportion by 5.2%, and induces a transition in the silicate network from a disordered to an ordered structure. Water quenching experiments combined with XRD and Raman spectroscopy confirm that the magnetic field alters solute transport by suppressing melt flow, thereby regulating the solidification shrinkage behavior and microstructure of the mold flux. This study reveals, for the first time, the performance evolution mechanism of ultra-high speed casting mold flux under an electromagnetic field, providing a theoretical basis for developing mold fluxes compatible with EMBr technology and contributing to the industrial application of ultra-high speed continuous casting.

Crack breakout often occurs during the continuous casting process of peritectic steel, which seriously restricts the high-efficiency and high-quality production of peritectic steel continuous casting. Crack breakout mainly originates from solidification defects of the initial solidified shell in the mold. The phase transformation shrinkage of peritectic reaction forms air gaps, leading to uneven heat transfer and uneven thickness of the solidified shell, and crack breakout is prone to occur at the weak parts of the shell. This paper reviews the formation mechanism and conditions of depressions in peritectic steel continuous casting slabs, summarizes the typical characteristics and main influencing factors of slab corner crack breakout, wide-face off-corner breakout and wide-face center crack breakout, and also summarizes the influence laws of steel composition and process factors on crack formation. Aiming at the frequent crack breakout of peritectic steel, this paper puts forward requirements for improving crack breakout from aspects of process factors, mold flux properties and mold design, and points out that establishing a crack breakout risk prediction model for the continuous casting process based on the key influencing factors of crack breakout, and conducting early warning and timely intervention on accident precursor characteristics, is the development direction of future breakout prediction models.

To investigate the effect of electromagnetic swirling flow in the nozzle (EMSFN) technology on the molten steel flow behavior in a slab continuous casting mold, a water model system with a geometric scaling ratio of 3∶1 was established based on similarity criteria, using a slab mold (1 450 mm×200 mm) as the prototype. A mechanical swirling rotor was installed inside the submerged entry nozzle to simulate the external field intervention effect of EMSFN. The influence of the nozzle swirling flow on the fluid flow pattern, liquid level fluctuation, and velocity distribution within the mold under different outlet flow rates of water model system was systematically studied. The results show that under conventional casting conditions, the flow field in the mold is asymmetrically distributed, with interfering upward flow occurring in the lower recirculation zone. The liquid level fluctuation intensified with increasing outlet flow rate, exceeding ±2 mm near the nozzle. After applying the nozzle swirling flow, the flow field symmetry was significantly improved. The impingement point of the nozzle outflow on the narrow face shifted upward, effectively dissipating the kinetic energy of the lower flow and suppressing the lower vortex, thereby stabilizing the liquid level fluctuation within ±1 mm. This study confirms that applying nozzle swirling flow enables effective control of the mold flow field, which provides a theoretical basis for the industrial application of EMSFN technology in slab continuous casting.

High speed casting was used to cast the low carbon steel grades used for tinplate due to the narrow width. Sliver defects were frequently detected in tinplate, which caused high downgrade ratio and production cost. The micro analysis revealed that the primary cause of these linear defects was FeO type with small oxide points. Under high casting speeds, the heat flux density of the molten steel exceeded the critical heat flux density, resulting in longitudinal slab cracks , which subsequently evolved into linear defects during rolling. By reducing the Na₂O content to 1.47%, increasing the Li₂O content to 1.7%, and controlling the fluid flow through optimization the current parameters of FC mold, the FeO type sliver defects were sharply decreased.

High-speed slab continuous casting can significantly improve production efficiency; however, severe fluctuations in liquid surface flow velocity under high casting speeds are prone to causing slag entrainment defects, and most conventional slab continuous casters are not equipped with electromagnetic braking systems. To explore a low-cost and high-efficiency flow field control method under high casting speeds, this study proposes a new approach: suppressing rapid liquid surface flow by inserting baffle rods. Using a combination of numerical simulation and physical water modeling, a 920 mm×180 mm mold model was established. With the diameter (30, 50, 70 mm) and insertion depth (10, 15 cm) of cylindrical refractory rods as variables, the regulation laws of cylindrical baffle rods on the liquid surface flow velocity and fluctuation in the mold were investigated.The results show that the diameter of the baffle rod plays a dominant role in regulating the mold flow field. Compared with the condition without a baffle rod, the 70 mm baffle rod reduces the overall flow velocity by 19.5%, which is 3.2 times the reduction rate of the 30 mm baffle rod (6.1%). The reduction in liquid surface fluctuation increases from 11% to 39%, a 3.5-fold improvement. The effect of insertion depth on the flow field exhibits a threshold effect: only when the diameter is no less than 50 mm, increasing the insertion depth to 15 cm can additionally reduce the flow velocity by 3.2%-5.4% and the fluctuation by 12.8%. For small-diameter rods (30 mm), increasing the depth has a weak regulatory effect.The optimal parameter combination in this study is a baffle rod with a diameter of 70 mm and an insertion depth of 15 cm. Under this condition, the maximum liquid surface velocity (at point P2) decreases to 0.2 m/s (a cumulative reduction of 17.7%), and the velocity in the central area (at point P4) decreases to 0.115 m/s (a reduction of 22.8%). The fluctuation value in the jet core area (at point P2) decreases to 0.21 cm (a reduction of 40.0%), and the fluctuation in the slag entrainment risk area (P2/P5) stabilizes at 0.21-0.23 cm.

To address transverse cracks observed at the upper surface edge (100-200 mm from the edge) of rolled extra-thick plates made of pressure vessel steel 13MnNiMoR at a domestic steel plant, the formation mechanism and countermeasures for such edge cracks in continuous casting slabs were investigated through microscopic examination and hot ductility simulation. The results reveal that the matrix microstructure near the edge cracks consists of coarse grains, with a pro-eutectoid ferrite film—ranging in thickness from several tens to hundreds of micrometers—present along the prior austenite grain boundaries. Cracks initiate and propagate within this ferrite film, with their roots embedded in an un-cracked ferrite zone. Significant decarburization is observed around the cracks, while no precipitated phases are detected. Under the conventional secondary cooling conditions of the current slab casting process, the upper surface edge region (100-200 mm from the edge) experiences severe local overcooling in the straightening section, where the surface temperature drops to about 850 ℃—below the lower limit of the measured ductile-to-brittle transition temperature (DBTT) range of 880-890 ℃. The presence of pro-eutectoid ferrite films along austenite grain boundaries significantly reduces the material's plasticity. In the straightening segment, this low-temperature brittle zone is subjected to both high stress concentration (exceeding the material's strength limit) and additional tensile strain due to equipment misalignment (e.g., roll gap deviation or poor arc alignment). These combined stresses act on the brittle ferrite film, leading to intergranular cracking. It is concluded that the transverse cracks in 13MnNiMoR extra-thick slabs primarily result from the combined effects of casting machine precision, grain boundary strength, and cooling conditions, which extend during rolling into large-scale defects. Based on the DBTT range (880-890 ℃) identified via hot ductility tests and insights from a fully coupled thermal-mechanical model—which highlighted issues such as low temperature, high stress concentration, and additional strain caused by equipment inaccuracy in the straightening section—adjustments were made to the casting machine alignment and cooling process. A new controlled cooling strategy was implemented in production, along with tighter control of nitrogen and aluminum content during steelmaking. These measures significantly improved the crack resistance of the slab edges, reducing the incidence of edge cracks in 13MnNiMoR slabs from 15.39% to 1.67%.

Taking the base slag system of low-reactive CaO-Al₂O₃-Li₂O-B₂O₃-CaF₂ mold fluxes as the object, and with the aid of equipment such as the single hot thermocouple technique, scanning electron microscope, and X-ray diffraction analyzer, the effects of substituting B₂O₃ for CaF₂ on the properties of the slag such as crystallization temperature, critical cooling rate, crystallization incubation time and crystalline phases were investigated, and the crystallization kinetics analysis was carried out. The results show that using B₂O₃ instead of CaF₂ can effectively reduce the crystallization tendency of the slag. When the w(B₂O₃)/w(CaF₂) ratio increases from 0.44 to 2.25, the critical cooling rate rises. When the ratio of w(B₂O₃) to w(CaF₂) is 2.25, the critical cooling rate reaches 12 ℃/s, and the crystallization performance is the weakest. With the increase of the substitution amount of B₂O₃ for CaF₂, the crystallization inoculation time shows a trend of first increasing and then shortening. During the cooling process of the slag, the initial crystalline phase formed changes from CaAl₂O₄ to CaAl₄O₇. The change law of the full crystalline phase is CaAl₂O₄+CaF₂→CaAl₄O₇+CaF₂→CaAl₄O₇+CaF₂+Ca₅B₃O₉F. Kinetic analysis indicates that when w(B₂O₃)/w(CaF₂) is less than 1.6, the crystal growth changes from three-dimensional to two-dimensional as the temperature drops, with a transition temperature of 1 100 ℃. When w(B₂O₃)/w(CaF₂) is greater than or equal to 1.6, the crystals precipitated in the slag always grow in three dimensions. Moreover, as the substitution amount of B₂O₃ for CaF₂ increases, the precipitation of Ca₅B₃O₉F promotes the three-dimensional growth of the crystal. When the ratio of w(B₂O₃) to w(CaF₂) is 0.625 to 1, the crystallization performance of the slag is relatively weak, and the types of crystalline phases are fewer, which is more conducive to the regulation of crystallization performance.

The finite difference model for 320 mm×410 mm continuously cast bloom of 1.4418 martensite stainless steel was established based on the equipment condition in a domestic factory, and it was verified by the shell thickness and surface temperature in the plant. The solidification characteristic and mechanical reduction reasonability in continuous casting of 1.4418 martensite stainless steel were discussed numerically, and the most suitable casting speed was found as 0.45 m/min. Two sets of mechanical reduction parameters were designed with total reduction amount of 12 mm and 15 mm, respectively. The industrial test was carried out according to the optimized schemes by numerical modelling, and the successful operation was achieved within the rated power range of withdraw units. The best center quality of the bloom for 1.4418 martensite stainless steel was obtained when the casting speed was 0.45 m/min with the designed reduction amount for No.2—5 withdraw units about 4 mm, 4 mm, 4 mm and 3 mm respectively, and the pass rate for the level A flaw detection was measured to be around 97%, satisfying the requirement of batch production and delivery.

Both the pre and prost processing modules for the calculation of heat transfer and solidification in continuous casting were compiled to integrate with ProCAST simulation software by the treatment of bow geometry of the caster machine and the non-uniform water spray flux in the secondary cooling zone. The temperature distribution and solid fraction in both the longitudinal and transverse sections of the extra-thick slab were obtained by the numerical simulation of the practical continuous casting process. The results show that the liquid pool in the shape of “W” would form in the central broad section of the slab with the less water flux in the edge compared to that in the central broad face. The solidification homogeneity in the slab cross section could be improved by adjusting the spray flux in the secondary cooling zone.

To address the issues of flow field turbulence and unstable steel-slag interface in the thin slab continuous casting mold under high casting speed conditions, this study takes the FTSC thin slab mold and full-width single-segment electromagnetic braking (Ruler-EMBr) system of a steel plant as the research objects. A coupled model of Large Eddy Simulation (LES) and Volume of Fluid (VOF) is adopted for numerical simulation, with a focus on analyzing the influence law of different magnetic flux densities on the flow characteristics in the mold when the casting speed is 6.0 m/min. The results show that electromagnetic braking can effectively regulate the flow field in the mold, improve the stability of the steel-slag interface, and prevent the abnormal rise of the steel-slag interface. When the Ruler-EMBr system is applied with a magnetic flux density of 0.23 T, the maximum velocity of the steel-slag interface is controlled within 0.30 m/s, the maximum wave height is limited to 10 mm, the fluctuation range of the interface position is maintained within ±2 mm, and the turbulent kinetic energy of the steel-slag interface is suppressed below 0.045 J/kg. These findings fully verify the flow field regulation effect of the Ruler-EMBr system.

Center porosity is one of the main defects of continuous casting round billet. In order to reduce the center defect of the continuous casting round billet, the mechanical reduction is performed at the solidification end of the continuous casting round billet. According to the actual production situation of a factory, a three-dimensional finite heat transfer model of the continuous casting round billet was first established to simulate solidification, and according to the results of the heat transfer model, different reduction positions were determined. Then, the mechanical reduction processes of the continuous casting round billet with a diameter of 350 mm were simulated using a thermodynamic coupling model. At the same time, the relative change of the shrinkage cavity volume was used as the standard to evaluate the influence of the reduction position on the shrinkage cavity healing. Finally, the experiment of continuous casting round billet pressing was carried out. The results show that during the reduction process of continuous casting of round billet, the central shrinkage cavity became closed under the combined effects of metal filling and compression deformation. The reduction position corresponds to the solid fraction in the center of the continuous casting billet, and the metal flow condition is different at various reduction positions. Under the same reduction amount, when the central solid fraction of the continuous casting round billet increases, the flow range of the central metal of the continuous casting round billet will gradually decrease, and the relative flow distance of the metal will first increase, then remain unchanged, and finally decrease, and the central shrinkage cavity of the casting round billet will gradually decrease and finally become close. When the reduction is 15 mm, the optimal reduction interval of the continuous casting round billet is f_s=0.6-1.0. The experimental results show that the inner porosity of continuous casting round billet decreases after reduction.

To address the challenges of delayed quality monitoring and inefficient manual judgment in continuous casting production, an online quality monitoring and judgment system for casting slabs was developed based on multi-source data fusion. A three-tier architecture of "data acquisition, rule engine, and intelligent judgment" was designed, incorporating a real-time data acquisition module covering 707 process parameters across critical processes such as mold vibration and secondary cooling water distribution. A dynamically configurable three-tier metallurgical quality rule base was innovatively proposed, establishing a core rule engine for slab judgment to support real-time process parameter monitoring and anomaly warnings based on statistical process control (SPC), while achieving multi-level collaborative responses through sound-light alarms and WeChat notifications. To resolve defect traceability challenges, a three-dimensional coupling judgment model was established for mold level fluctuations, casting speed variations, and stopper rod movements, with formula-based characterization of the mapping relationship between process parameter fluctuations and quality defects. Application at a steel plant in Tangshan demonstrated significant improvements: through dynamic optimization of the metallurgical rule base and closed-loop feedback mechanisms for process parameters, the internal defect judgment accuracy increased from 25% to 85.6%, comprehensive judgment accuracy reached 98.5%, and manual re-inspection workload was reduced by over 75%. This research provides a full-process solution of "rule configuration, process monitoring, and quality traceability" for digital control of continuous casting, effectively addressing industry pain points such as outdated knowledge updates in traditional expert systems and insufficient interpretability of data-driven models.

This study utilizes a low-Reynolds number k-ε turbulence model to construct a three-dimensional magnetohydrodynamic coupling numerical model, investigating the impact of electromagnetic stirring (EMS) current intensity and stirrer positioning on the flow, heat transfer, and solidification behavior of molten steel within the continuous casting mold for 140 mm×140 mm billets of 82B steel at a particular steel plant. The results demonstrate that the current intensity is a critical determinant of stirring efficacy; increasing the current intensity leads to a reduction in the depth of the primary steel jet impact, an increase in tangential velocity, and accelerated dissipation of superheat within the mold, resulting in a thinner solidified shell and a scouring effect on the shell due to backflow near the mold, which appears a slow growth zone in shell thickness. Variations in stirrer positioning also alter the flow field characteristics; the lower the position, the more the main flow core descends, and the position and shape of the vortex change accordingly, reducing liquid surface fluctuations, although an excessively high exit tangential velocity may lead to uneven shell growth. For the continuous casting production of high-carbon steel billets at this plant, it is beneficial to appropriately elevate the EMS installation to 515 mm and enhance the stirring current intensity to the rated 600 A. This configuration keeps the liquid surface fluctuations within a controllable range and further promotes rapid dissipation of superheated molten steel, while also ensuring a certain degree of undercooling at the center of the foot rolling area, facilitating early nucleation of molten steel and enhancing the ratio of equiaxed grains, which is advantageous for improving the center segregation of the billet.

Focusing on slab defects such as longitudinal cracks and depressions in 2Cr13 martensitic stainless steel produced at a steel plant, the high-temperature characteristics of the steel and the physicochemical properties of the used mold fluxes were systematically investigated. Results indicate that 2Cr13 martensitic stainless steel undergoes a peritectic reaction during solidification, with the initial solid fraction reaching 88.77% at the onset of this reaction. The DSC curves exhibit significant fluctuations at high-temperature stage, indicating a poor thermal stability of the steel. Additionally, the steel has also the characteristics of high tensile strength but low thermal plasticity. These characteristics will easy to cause the non-uniform growth of the initial solidification shell, leading to the formation of the slab defects. Comparative analysis of two commercial mold fluxes (S1 and S2) reveals similar effective chemical compositions, viscosity, and melting temperature. However, S2 flux contains a significant lower proportion of pre-melted material compared to S1 flux. During actual application, low-melting-point Na₂CO₃ in the S2 flux tends to melt preferentially, inducing segregation phenomena. Consequently, the Na₂CO₃ content in the liquid slag exceeds designed values, reducing both the viscosity and break temperature of the slag. This results in an uneven distribution of flux films and weakens the heat transfer regulation capacity, thereby increasing the propensity for longitudinal cracks and depressions in the cast slab. These findings provide crucial insights for optimizing mold flux design and casting parameters in the continuous casting of martensitic stainless steels.

Based on a finite element model, the magnetic induction intensity and Joule heat obtained from Maxwell were imported into Fluent as source terms to investigate the flow field and temperature field of molten steel in a five-strand four-channel induction heating tundish under the influence of ladle heat dissipation. The results show that, during the casting process, the temperatures at the three outlets of the tundish without ladle heat dissipation decrease slowly and exhibit a similar trend, with a temperature drop of less than 1 K among the outlets. In contrast, under the influence of ladle heat dissipation, the temperatures at the three outlets differ significantly, with a temperature difference of nearly 20 K between the early and late stages of casting. Although induction heating compensates for the temperature loss of molten steel in the ladle, it does not significantly reduce the temperature variation across different casting periods. The maximum outlet temperature is 11 K lower than the initial casting temperature. When the induction heating power is adjusted during casting, the maximum temperature difference between different time points remains within 2 K, and the temperatures remain relatively consistent across different periods and outlets.

The flow behavior of molten steel in the Ruhrstahl-Heraeus (RH) furnace critically influences the efficiency of refining processes, including decarburization and impurity removal. While the widely employed gas-stirring technique effectively enhances molten steel circulation, the associated bubble flow is difficult to control precisely, potentially leading to flow instabilities and uneven energy distribution that limit further gains in refining efficiency. Therefore, in order to optimize the flow behavior within the RH furnace, this paper conducts an optimization simulation of the electromagnetic stirrer in the RH riser. The results show that the inner diameter of the iron core should be minimized to 750 mm to maximize the magnetic field strength; The outer diameter and thickness are optimized to 1 500 mm and 100 mm respectively, at which point the magnetic field performance and material cost are balanced; The stirrer is positioned 125 mm from the top to generate the maximum force. When the coil is 75 mm away from the molten steel, the magnetic field distribution of the iron core is the most uniform, without local magnetic concentration areas, and the magnetic field strength of the molten steel reaches a relatively high level; The simulation determines that 110 turns of coil, a frequency of 5 Hz, and an current below 250 A are the optimal combination, which can generate an average magnetic induction intensity of over 0.04 T and achieve the best matching of electromagnetic force and penetration depth. After coupling the optimized electromagnetic field into the flow field, the circulation flow increases by 6.3%, which proves the optimization effect of the electromagnetic stirrer. This study clearly defines a set of optimal three-phase six-level electromagnetic stirrer parameters for the RH riser when the inner diameter is 650 mm, providing theoretical basis and parameter guidance for its industrial design.

Tundish plasma heating technology could reduce the tapping temperature and superheat fluctuation range, as well as improve the quality of casting billets, whose equipment has the advantages of easy installation, high heating efficiency, and low energy consumption. Focusing on the hot issues related to tundish plasma heating technology, the equipment characteristics were systematically described, the application progress of plasma heating technology in slab production was introduced, and the metallurgical effects of plasma heating technology in practical applications were analyzed. The effect of the device on the temperature, chemical composition, and inclusion removal in molten steel was revealed. It is demonstrated that the first domestically developed new hollow graphite electrode heating device has achieved a breakthrough in tundish heating technology. It effectively meets the production requirements of low-, medium-, and high-carbon steels, offering an effective solution to the problem of temperature heat loss in the tundish, and achieving the goal of energy-saving and consumption reduction.

To optimize the inclusion control level of GCr15 bearing steel and explore the influence of an asymmetric side-port submerged entry nozzle on the spatial distribution of inclusions in continuous casting bloom, field sampling and analysis were performed on the bloom. A numerical model was established that simultaneously considers the three-dimensional unsteady flow, heat transfer, solidification and the coupling of inclusion movement throughout the continuous casting process, as well as the capture of inclusions at the solidification front, to realize the prediction of the spatial position of residual inclusions in the continuous casting bloom at different times. The proportion of inclusions floating to the slag/steel interface increased from 1.9% to 17.9% when the particle size increased from 1 μm to 50 μm during the continuous casting process. Residual inclusions within the bloom exhibited an asymmetric distribution, with a tendency to accumulate 7.8-10.5 mm beneath the bloom surface. Inclusions less than 10 μm were more likely to be transported by molten steel flow into the deeper regions of the liquid pool, while inclusions with a particle size greater than 10 μm tend to accumulate at 1/4 to 1/3 of the inner arc side of the bloom.

The withdrawal-induced leakage of molten steel from the dummy bar head during the start-up phase of billet continuous casting is a major constraint on production continuity and equipment safety. This issue stems from systematic shortcomings in conventional dummy bar practices, including the design of the dummy bar head, cold charge parameters, auxiliary equipment, and monitoring and control mechanisms. In response, this paper introduces an integrated plug-pulling process that combines multi-dimensional innovations in the dummy bar head design, intelligent and precise regulation of cold charge parameters, development of new auxiliary devices, and smart adaptive monitoring and control. Industrial trials confirm that the proposed approach reduces the monthly average number of leakage incidents caused by dummy bar withdrawal from 8 to 2, increases the monthly average mold casting capacity by 32.8%, and decreases the current fluctuation amplitude of the withdrawal-straightening motor by 40%. By enabling intelligent monitoring and adaptive control, the start-up casting process has been transformed from an experience-driven, reactive operation into a data-driven, proactive prevention system. This provides comprehensive technical support for high-efficiency and safe billet continuous casting.

This study investigates the effects of the upward traveling wave magnetic field (TMF) operating at different frequencies on the solidification process, microstructure refinement, and mechanical properties of an Al-7wt.% Si binary alloy. The alloy solidification samples were prepared using an electromagnetic casting device. A magnetic-flow-thermal multi-field coupling model was employed for numerical simulation of the melt solidification process, calculating the forced convection and liquid phase distribution within the Al-7 wt.% Si alloy melt subjected to TMF treatment. The results indicate that under 75 A 12 Hz-TMF, the peak velocity of the flow field within the Al-7 wt.% Si alloy melt reached 0.023 m/s. Under the combined effects of forced convection and Joule heating, the dendrite arm spacing (DAS) of the samples treated at 8 Hz-TMF was refined to 127.8 μm. Meanwhile, the ultimate tensile strength and elongation after fracture increased from 100.8 MPa and 6.9% (natural solidification, NMF) to 113.7 MPa and 8.3%. When the TMF frequency was increased to 12 Hz, the Joule heating generated within the melt gradually increased, leading to a reduction in the temperature gradient during the solidification process, thereby slowing down the solidification rate of the castings, and the refinement effect on the solidification structure decreased, with the average DAS increasing to 140.3 μm, and the mechanical properties consequently degraded. The results demonstrate that the convection induced by TMF and Joule heating are the primary reasons for the refinement of the solidification microstructure and the enhancement of mechanical properties. These findings provide a theoretical basis for the research on improving the quality and mechanical properties of castings through applied electromagnetic field casting technology.

To address center segregation and shrinkage cavities in GCr15 bearing steel continuous casting billets, a steel plant established a solidification heat transfer model for large billets by integrating principles of heat transfer, steel grade characteristics, and the spatial structure of the withdrawal and straightening equipment, employing the finite difference method. Leveraging the accuracy of this model, a final-stage reduction technology was developed and implemented on a seven-stand withdrawal and straightening system with 1 200 mm equal roller spacing, achieving safe and stable production with a total reduction of 22 mm. With this technology, the center carbon segregation index of high-carbon steel billets has been consistently maintained within 0.95-1.05, the proportion of billets with a carbon extreme deviation not exceeding 0.08% has increased to 98.4%, and 99.95% of billets now exhibit center shrinkage cavities of grade 0.5 or lower. This breakthrough enhancement in internal billet quality has enabled the plant to adopt a low compression ratio rolling process for producing large-size bars, which achieve an ultrasonic testing pass rate exceeding 99.95% in accordance with the AA grade of GB/T 4162.

As the primary feedstock for X65 pipeline steel, the continuous casting slab is prone to macrosegregation, which is one of the key defects limiting the performance of steel materials. To control solute segregation during the continuous casting process, a multiphase solidification model was established by coupling melt flow, macroscopic heat transfer, microstructural solidification evolution, and solute transport, with full consideration of the soft reduction process at the solidification end. The model was applied to systematically investigate the influence mechanisms of superheat and casting speed on slab macrosegregation. The computational accuracy was validated through carbon-sulfur analysis of industrial slabs. The results show that as the superheat increases from 14 ℃ to 30 ℃, columnar dendrite growth is enhanced and the equiaxed grain zone narrows. For every 8 ℃ increase in superheat, the equiaxed zone at the slab center decreases by 0.6-0.8 mm, and the segregation index increases by approximately 1.39%. The effect of casting speed on segregation control depends on the matching between the solidification end and the soft reduction zone: at 0.8 m/min, the solidification end (18.46 m) occurs before the reduction zone, resulting in ineffective reduction and a segregation index of 1.151; at 1.1 m/min, the solidification end (23.55 m) falls entirely within the reduction zone, where the reduction effect is most effective, yielding the lowest segregation index of 1.071; at 1.2 m/min, the solidification end (27.95 m) extends beyond the reduction zone, where insufficient coverage causes the segregation index to rise slightly to 1.082. This study clarifies the quantitative relationship among superheat, casting speed, and central segregation under fixed soft reduction conditions, providing a theoretical basis and process optimization guidance for the precise control of macrosegregation in slab continuous casting.

With the increasing demand for low-carbon and ultra-low-carbon steel smelting, low-carbon spinel-carbon refractories for continuous casting are subject to more rigorous requirements for slag corrosion resistance and thermal shock resistance. This study systematically investigates the effect of nano-carbon/magnesium aluminate spinel (C/MgAl₂O₄) composite powder content on the properties of low-carbon magnesia-alumina spinel-carbon (MgAl₂O₄-C) refractories for stopper rods. The results indicate that the composite powder consists primarily of irregularly shaped particles with rough surfaces, in which nano-carbon is distributed between MgAl₂O₄ grains and adhered to spinel particle surfaces, forming a unique clustered morphology. The optimal performance of MgAl₂O₄-C refractories was achieved with 6.3% composite powder addition (sample C/MA-2), showing 15.4%, 19.6%, and 45% enhancements in the cold modulus of rupture (CMOR), the cold crushing strength (CCS), and the hot modulus of rupture (HMOR), respectively, compared to the composite-free sample (C/MA-0). Sample C/MA-2 exhibited the best thermal shock resistance, showing a 11.9% higher the thermal shock resistance of than C/MA-0. Furthermore, the erosion depth of C/MA-2 was reduced by 19.6% relative to C/MA-0, demonstrating superior slag corrosion resistance.

The wetting characteristic of mold flux is an important factor affecting the surface quality of low-density steel billets. By using a high-temperature contact angle measuring instrument in combination with interfacial structure characterization, the effects of (CaO+BaO)/Al₂O₃ mass ratio and substitution of B₂O₃ for SiO₂ on the wetting characteristic between CaO-Al₂O₃-based mold flux and low-density steel are studied. Results show that as the (CaO+BaO)/Al₂O₃ mass ratio increases from 0.87 to 1.59 and B₂O₃ gradually replaces SiO₂, the initial temperature at which the contact angle begins to rapidly reduce decreases from 1 480 ℃ to 1 330 ℃, 1 170 ℃, and first decreases from 1 300 ℃ to 1 170 ℃ and then increases to 1 180 ℃, respectively. The evolution behavior of contact angle and adhesion work is similar to the change in temperature. As the (CaO+BaO)/Al₂O₃ mass ratio increases, the thickness of element diffusion layer at the steel-slag interface increases from 1 μm to 5 μm. As B₂O₃ replaces SiO₂, the thickness of element diffusion layer at the interface first decreases from 9 μm to 5 μm and then increases to 15 μm. Mn diffuses and transfers from the steel matrix to the interface, and its content gradually decreases. Al diffuses and transfers from the steel matrix to the interface, and due to the high Al content in the slag at the interface, its content shows an increasing trend. The change of Si content is not obvious. Based on this, the mass ratio of (CaO+BaO)/Al₂O₃ is controlled at around 1.59, and the contents of B₂O₃ and SiO₂ are controlled at 5%, which are conducive to maintaining the low reactivity of mold flux and improving its wetting characteristics with low-density steel.

Al₂O₃-C materials were prepared using high-alumina bauxite clinker as the primary raw material, flake graphite as the carbon source, metallic silicon and silicon carbide as additives, and phenolic resin as the binder, with varying proportions of reactive alumina micropowder incorporated. The particle size distribution, bulk density, and flowability of the granulated feedstock, along with the cold modulus of rupture, apparent porosity, bulk density, permanent linear change after heating, hot modulus of rupture, thermal expansion, and thermal shock resistance of the Al₂O₃-C materials, were measured in accordance with relevant standards. This study investigated the effect of reactive alumina micropowder addition on the properties of Al₂O₃-C refractories for the three major continuous casting components, based on a formulation with high-alumina bauxite clinker as the main raw material and the mass fraction of graphite is 23%. The results indicated that with increasing reactive alumina micropowder content, the granulation quality and flowability of the Al₂O₃-C granules first improved and then deteriorated. Incorporating reactive alumina micropowder into the Al₂O₃-C refractories reduced the apparent porosity and enhanced the bulk density, cold modulus of rupture, and hot modulus of rupture. Following heat treatment at 1 100 ℃ and 1 600 ℃, all samples exhibited varying degrees of shrinkage, with the linear shrinkage increasing progressively as the reactive alumina micropowder content increased. Moreover, with higher additions of reactive alumina micropowder, the thermal expansion coefficient of the high-alumina bauxite clinker-based Al₂O₃-C refractories gradually increased, while their thermal shock resistance progressively deteriorated.

The effect of stand electromagnetic stirring on the fluid flow and heat transfer behavior of molten steel during continuous casting of ø800 mm round billet was investigated. The results indicate that the stirring position has an important influence on the flow state, flow direction, stirred volume, and cooling rate in the molten steel. Within the strand zone, lowering the stirring position reduces the angle between the radio flow direction of the solidification front from 30° to 0°, while the helical angel of the longitudinal flow trajectory increases from 30° to 55°. The flow tendency toward the core weakened, and the stirring velocity at the solidification front decreased from 0.008 m/s to 0.003 6 m/s. Among them, when the stirrer is located in the upper-middle section of the CET zone, the flow stability of the molten steel is significantly improved. The stirring speed at the solidification front is 0.005 6 m/s, and the effective stirring volume of molten steel is the largest, which is 0.045 3 m³, with a tendency to flow to the core. In terms of heat transfer, the heat loss of molten steel in the stirring zone is faster. When the stirring is in the upper-middle section of the CET zone, it is beneficial to improve the equiaxed crystal rate and accelerate the solidification rate of the billet. Therefore, the stand electromagnetic stirring position in the upper-middle section of the CET zone is the best, which provides an important guiding significance for the optimization of the electromagnetic stirring process.

As a critical functional refractory component in continuous casting, the tundish stopper rod directly influences process continuity, molten steel cleanliness, and final product quality. Traditional Al₂O₃-C stopper rods face technical limitations—including chemical erosion, carbon oxidation, and insufficient high-temperature strength—when casting calcium-treated steels, high-manganese steels, and high-oxygen steels. This paper examines the performance advantages of MgO-C refractories as an alternative, focusing on their erosion-resistance mechanism and its effects on steel cleanliness and thermal shock resistance. Studies indicate that MgO-C materials inhibit the formation of low-melting-point phases due to the high melting point and low reactivity of MgO with steel components; a dense MgO reaction layer formed on the surface effectively blocks molten steel penetration; and the graphite component provides excellent thermal shock resistance and high-temperature structural stability. Furthermore, MgO-C materials help improve steel cleanliness by adsorbing inclusions such as Al₂O₃ and SiO₂ and mitigating carbon pickup. However, challenges remain for industrial application, including balancing carbon-free requirements with high performance, ensuring reliability in long-sized stopper rod structures, and controlling costs. Future efforts should promote wider adoption of MgO-C stopper rods in efficient continuous casting through multi-scale simulation, composite design, and process optimization.

The production of high-strength and high-toughness spring steel is a key component in the lightweight development trend of the automotive industry. To address the issue of significant macrosegregation control in the continuous casting of 55SiCrA spring steel, this study develops a coupled multi-physics numerical model integrating "flow-heat transfer-electromagnetic field-solute transport" for the actual industrial continuous casting process of 280 mm×280 mm spring steel blooms. The accuracy of the solute field predicted by the model was verified through industrial-scale sampling. Furthermore, the effects of submerged entry nozzle (SEN) structure, casting superheat, and mold electromagnetic stirring (M-EMS) on solute transport during continuous casting were systematically investigated. The results indicate that the SEN structure significantly influences molten steel flow and solute transport behavior. The use of a four-port nozzle reduces the severity of negative segregation under bloom surface and eliminates its asymmetry. Increasing the superheat prolongs solute precipitation and transport at the solidification front, thereby intensifying negative segregation under bloom surface. M-EMS enhances molten steel turbulence and accelerates heat dissipation, which helps mitigate the original negative segregation; however, it also increases the scouring effect at the solidification front, potentially leading to the formation of a secondary negative segregation band within the mushy zone.

To meet the stringent non-magnetic requirements for 316L austenitic stainless steel in applications such as nuclear power and mobile devices, it is essential to precisely control the residual ferrite content in the cast slab. This study investigates a high-nickel, high-nitrogen 316L austenitic stainless steel slab produced industrially. Using metallographic examination and electron backscatter diffraction (EBSD), the morphology, distribution, and content of ferrite across the thickness direction at the slab centerline were characterized, along with the identification of secondary precipitated phases. Thermodynamic simulations were employed to analyze the equilibrium solidification process, and the predictive accuracy of various empirical models for solidification mode and ferrite content was evaluated. The results indicate that the ferrite morphology varies from granular near the surface to short rod-like and finally to a semi-network morphology toward the center, predominantly along austenite grain boundaries. The ferrite content (volume fraction)ranges from 0.14% to 1.47%, with the highest value observed at the center, meeting the non-magnetic criteria. The main secondary precipitates were identified as chi-phase and sigma-phase. Near the surface, ferrite precipitates as discrete particles at austenite grain boundaries, with partial transformation into chi-phase. The high cooling rate at the surface inhibits complete transformation, resulting in a coupled ferrite/chi-phase microstructure. In contrast, the semi-network ferrite in the central region has largely transformed into sigma-phase. Although thermodynamic calculations predict single-phase austenitic solidification (A-mode), experimental observations confirm austenite-ferrite (AF-mode) solidification. Among five chromium/nickel equivalent formulas and the WRC-1992 diagram evaluated, only the Hull formula accurately predicts the ferrite content (1%-2%), consistent with measured results. Other models either overpredict (3% or 7%-10%) or incorrectly predict fully austenitic solidification.

Spinel carbon refractories exhibit outstanding thermal shock resistance and corrosion resistance by molten steel, rendering them well-suited for applications in continuous casting components. Two types of spinel carbon refractories were prepared using fused spinel, sintered spinel, graphite, and Al-Si alloy powders as primary raw materials, and the physical property and corrosion tests were carried out. The results show that: At relatively high temperatures (above 1 400 ℃), the Al-Si alloy powders reacts with CO in vapor form to produce Al₂O₃ and SiC fibers, which strengthen the bonding of the matrix, and part of the silicon forms SiC with a granular morphology under corrosion conditions; Fused spinel, with its high density, can physically impede the infiltration of molten slag, and the erosion it undergoes is primarily characterized by chemical dissolution at the raw material boundary. In contrast, sintered spinel has a lower density than fused spinel, leading to weaker resistance against molten slag penetration. Nevertheless, it boasts higher activity compared to fused spinel and a stronger capacity to dissolve MnO and FeO in the slag, thereby demonstrating enhanced resistance to glass phase dissolution. As a result, both spinel carbon refractories exhibit excellent corrosion resistance.

The problem of low qualification rate of AK-B3 ball mill steel had been appeared, the microstructure, inclusions and precipitation around defects of flaw detection were detected and analyzed by OM, SEM and metal in situ analyzer, the segregation of chemical elements of continuous casting billets was analyzed. The results show that there were strip shaped cracks, micro-cracks and micro-viods distributed along rolling direction. The side morphology of cracks were cleavage fracture, inclusion of MnS and TiN occurred around cracks. Chemical elements of Mn, P and S of continuous casting billet exhibited obviously segregation, which was the main reason for the low qualification rate of flaw detection. The qualification rate of flaw detection increased from 85% to 94% through improving smelting and continuous casting processes, enhancing the cleanliness of molten steel and the internal quality of casting billets, optimizing processes of slow cooling of billets and heating process of furnace diminution thermal stress and increasing rolling reduction of continuous casting billets.