To enhance the intelligent control level of the converter steelmaking process, the research progress in models for endpoint control and slag foaming prediction was reviewed. Through a systematic review of relevant research, the evolution of endpoint control models from static approaches, including mechanistic, incremental, and intelligent models, to dynamic control models based on sub-lance, off-gas, and image data was analyzed.The development trend of slag foaming prediction models from single-modal prediction model based on audio, image and off-gas data to multi-modal prediction model combining these data sources was discussed.The review indicates that while existing models have achieved certain success in both theory and industrial applications, they still face significant challenges, particularly in terms of robustness and interpretability under complex operating conditions, as well as a strong dependence on high-quality data. This study concludes that the deep integration of metallurgical mechanisms with data-driven methods, coupled with the development of efficient multi-modal information fusion techniques, represents a key direction for improving the prediction accuracy and robustness of the models in the future.

Vacuum Degassing (VD) refining can effectively remove gases, sulfur, and inclusions in steel. However, low-melting-point large-size non-metallic inclusions and high aluminum loss in steel occurred during VD refining in commercial production. To solve the problems, the influence of VD refining on non-metallic inclusions and aluminum loss was summarized, focusing on the formation mechanisms and controlling methods of low-melting-point large-size inclusions and aluminum-loss. The formation mechanism of large-size inclusions included the following two: exogenous by entrainment and endogenous. The entrainment-type large-size inclusions could be decreased by regulating argon stirring intensity during the later period of VD refining. While endogenous large-size inclusions could be controlled by reducing CaO activity in refining slag, increasing Al₂O₃ content in slag, decreasing [Al] content and controlling [Ca] content in steel. The aluminum loss during VD processing could be reduced by decreasing the initial aluminum content in steel, along with increasing slag basicity (CaO/SiO₂) and Al₂O₃ content appropriately.

Short-process steelmaking is a key approach to promoting the green and low-carbon transformation of China’s steel industry. As the core equipment of this route, the electric arc furnace (EAF) is often constrained by limited bath stirring and metallurgical efficiency, which hinders its wider application. In this study, the flow behavior and mixing characteristics of a three-hole bottom-blown EAF under different gas flow rates and combined side-bottom blowing conditions were systematically investigated using both physical and numerical simulations. A 1∶8 scale water model experiment was conducted to examine bath mixing under varying bottom-blowing and side-bottom combined blowing operations, while a three-dimensional CFD model was established to analyze the velocity distribution at the steel-slag interface under different blowing parameters. The results show that the position of the bottom nozzles significantly affects bath stirring and interfacial mass transfer. With increasing the distance from the nozzles to the furnace center, the mixing time increases, while the dead-zone area at the steel-slag interface first decreases and then increases. The optimal nozzle location is 0.4R-0.5R. Under single bottom-blowing conditions, there exists an optimal flow rate range (0.1-0.32 L/min, corresponding to 20-60 L/min at industrial scale), beyond which stirring efficiency saturates. Side-bottom combined blowing can generate a through-circulation flow field and significantly improve mixing efficiency. However, when the bottom-blowing rate exceeds 0.63 L/min (120 L/min at industrial scale), the mixing efficiency declines. These findings provide theoretical guidance for optimizing EAF blowing operations, with important implications for improving the efficiency of short-process steelmaking and reducing energy consumption and carbon emissions.

Under conditions of high scrap ratio, the total iron (T.Fe) content in slag during electric arc furnace smelting is relatively high, and the T.Fe content in slag is a key factor affecting the dephosphorization effect and the steel yield of electric arc furnaces (EAF). Currently, the primary method for controlling the T.Fe content in slag involves injecting carbon powder, optimizing carbon powder injection parameters is of great significance for improving EAF smelting quality. Taking the EAF smelting process with a 60% scrap steel ratio in a steel plant as the research object, focusing on the control effect of carbon powder injection flow rate on T.Fe in slag, the variation law of the T.Fe content in slag was systematically analyzed, and its influence mechanism on dephosphorization effect was explored.The research results show that after scrap melting, the T.Fe content in slag gradually increases with the progress of oxygen supply, and the mass fraction of T.Fe in the final slag can reach up to 35%. Carbon powder injection can effectively reduce the T.Fe content in slag and improve dephosphorization effect, but there is an optimal regulatory range for its flow rate. When the flow rate is lower than 60 kg/min, the T.Fe content in slag continues to rise in the middle and late stages of smelting,while exceeding 90 kg/min leads to carbon powder saturation and waste. Carbon powder injection enhances dephosphorization by reducing the proportion of FeO composite phase and increasing the proportion of phosphorus-rich 2CaO·SiO₂ phase in slag. The optimal effect is achieved when the flow rate is controlled at 55-70  kg/min. Compared with the working condition without carbon powder injection, the average T.Fe content in the final slag decreases from 29% to 20%, and the average dephosphorization rate increases from 60% to 80%.

The foaming behavior of slag significantly influences the submerged arc operation and energy efficiency of electric arc furnaces. The foaming characteristics of the CaO-SiO₂-FeO-Al₂O₃-MgO slag system under homogeneous melting conditions were systematically investigated. Based on thermodynamic calculations, the experimental composition ranges were determined as follows: w(FeO)=21%-30%,w(MgO)=3%-7%, and basicity 1.0-2.2. Through single-factor experiments and physical property analysis, the following conclusions were drawn: as the mass fraction of FeO increased from 21% to 25%, the foaming index rose significantly due to decreased viscosity. And a further increase to 30% slowed the growth trend, attributed to increased density and surface tension. Increasing basicity caused a non-monotonic change in the foaming index, with a minimum observed at 1.25 and a maximum at 1.7, resulting from the combined effects of decreased viscosity and increased surface tension and density. The mass fraction of MgO showed a negligible effect on the foaming index, owing to its limited ability to modify viscosity and surface tension. Additionally, high-temperature experiments involving solid-liquid mixtures (with similar liquid phase composition) revealed that the solid particle content affected foaming behavior in a parabolic trend.

As a high-carbon emitting sector, the steel industry accounts for approximately 7% of global CO₂ emissions. Against the backdrop of the “dual carbon” goals, there is an urgent need to develop carbon reduction and CO₂ resource utilization technologies to promote the industry's green transformation. Refining, as a critical stage in the steelmaking process, currently has limited application of CO₂, particularly in studies of ultra-low-carbon Fe-C alloy systems under atmospheric pressure conditions. The reaction mechanism of CO₂ in ultra-low-carbon Fe-C alloy melt was systematically studied using FactSage thermodynamic calculations and high-temperature thermal experiments, with a focus on analyzing the effects of CO₂ injection flow rate, temperature, and injection duration on the evolution of carbon content in the melt. The results indicated that CO₂ injection caused carbon enrichment in the melt, with the enrichment rate significantly increasing with higher flow rates and temperatures. When the CO₂ flow rate increased from 40 mL/min to 80 mL/min, the enrichment rate rose from 0.001 81 %/min to 0.003 19 %/min, representing a 76% increase. After prolonged injection, the carbon mass fraction eventually stabilized at around 0.11% in the melt, reaching a dynamic equilibrium. This study provides theoretical basis and process parameter support for the industrial application of CO₂ in the refining of ultra-low-carbon steel.

When aluminum is used for deoxidation in tinplate production, a large amount of hard, brittle Al₂O₃ inclusions are formed. As the cold-rolled thin sheet of this steel demands high surface quality, it is necessary to control the quantity and morphology of hard, brittle alumina-type inclusions. The calcium treatment process can modify the morphology and particle size of alumina inclusions. The influence of calcium and sulfur content in the steel on the modification of alumina inclusions was investigated through industrial trials and thermodynamic calculations, and the effect of temperature on inclusion types was also studied. The industrial trial results demonstrated that after 3 minutes of calcium treatment, the average size of inclusions decreased from 2.01-2.61 μm to 1.44-1.60  μm, while the number density of inclusions increased from 29.85-46.51 counts/mm² to 69.85-94.91 counts/mm². Upon exiting the ladle furnace, the average inclusion size increased to 1.82-2.43 μm, and the number density decreased to 39.95-53.05 counts/mm². From refining to casting, the decrease in molten steel temperature leads to the precipitation of CaS inclusions, resulting in a narrowing of the liquid window. Therefore, the molten steel composition significantly affects the efficacy of Ca treatment for inclusion modification. Rational control of the molten steel composition enables the Ca to modify Al₂O₃ inclusions into liquid calcium aluminates, thereby reducing the risk of nozzle clogging.

During railway track changs, frequent impact and contact occur, which imposes strict requirements on the mechanical properties of steel. Therefore, high manganese steel is often used. A study was conducted on the evolution of steel and slag composition, as well as the composition, quantity, morphology, and size of non-metallic inclusions during the LF refining process of high manganese steel for special tracks produced  by a domestic steel plant.The results indicated that the main inclusions in the high manganese steel were MnO-Al₂O₃-MgO-CaO-SiO₂-MnS inclusions. The inclusions entering the LF station were mainly MnO-SiO₂-CaO-Al₂O₃-MgO composite inclusions, with sizes ranging from 1.01  μm to 43.98 μm, and presented as a three-layer structure with a regular spherical shape.After deoxidation and alloying at the LF exit, the size and quantity of the formed inclusions decreased significantly. The large-sized inclusions were mainly those of the CaO-Al₂O₃-MgO-MnO system, with irregular shapes. These inclusions no longer contained  SiO₂, and the Mn content in the inclusions was also greatly reduced.After LF refining, the average diameter, maximum diameter, number density, and area fraction of inclusions all showed an decreasing trend overall, while the basicity of the slag showed an increasing trend overall. The mass fraction of T.O in steel decreases from 16.90×10^-6 to 6.65×10^-6, indicated a good deoxidation effect.Thermodynamic calculations were performed using FactSage. The results showed that with the increasing of T.Al content in steel, Al₂O₃ and CaS gradually increased in inclusions; with the increasing of T.Ca content in steel， CaS and CaO gradually increased in inclusions, while Al₂O₃ gradually decreased. The calculated results have a good correspondence with the actual results.

The submerged entry nozzle is one of the key factors determining the molten steel flow field in the mold and plays an irreplaceable role in suppressing excessive meniscus fluctuations, preventing poor melting of the meniscus protective slag and regulating the molten steel flow field in the mold. Using high-temperature quantitative velocity measurement method and numerical simulation methods, the effects of 38 mm and  48 mm inner diameter convex-bottom SEN, and 48 mm inner diameter wavy-bottom SEN on the flow field, argon bubble distribution, meniscus fluctuations, solidification, and inclusion capture in the 840 mm×180 mm continuous casting mold under different casting speeds were studied. High-temperature velocimetry measurements of mold surface velocity were conducted for 38 mm inner diameter convex-bottom SEN at casting speeds of 0.8, 1.0, and 1.2 m/min. The good agreements between measurement and numerical simulation results validated the reliability of the mathematical model. The simulation results showed that when the casting speed was 1.2 m/min, the mold with 48 mm inner diameter wavy-bottom SEN showed smaller surface velocity, more uniform bubble distribution, reasonable overall meniscus fluctuations, uniform solidifying shell growth, and fewer captured inclusions (≤150 μm), demonstrating the best overall performance.

For the 200 mm×800 mm twin-strand slab mold, physical simulation experiment with a 1∶1 water model and numerical simulations based on the VOF multiphase flow and DPM discrete phase models were employed to systematically investigate the effects of nozzle structure parameters (bottom shape, inclination angle, and immersion depth) and process parameters (gas flow rate) on the flow field characteristics and slag layer behavior within the mold.The research found that a concave bottom nozzle combined with an 18° inclination angle could significantly reduce liquid surface fluctuations and flow velocity, enhancing the stability of the flow field.An immersion depth of 150 mm could effectively mitigate the disturbance of the flow to the liquid surface, and an gas blowing rate of 4-6 L/min ensured uniform slag layer coverage, preventing the exposure of molten steel. The study revealed the dominant role of the nozzle bottom shape and inclination angle, and proposed an optimized parameter combination, providing theoretical basis and practical guidance for improving the stability and quality of the cast slab in the continuous casting process of special cross-section slabs.

To investigate the redistribution of rare earths in steel ingots after electroslag remelting,the computational fluid dynamics(CFD)method was employed to simulate the interaction between rare earths and molten steel,heat transfer laws,and solidification segregation during the ingot casting process.Visualization of the temperature field,flow field distribution,and solidification segregation in the ingot was achieved,and the effects of key parameters on rare earth distribution were analyzed.The results show that when the casting temperature increases from 1 550 ℃ to 1  650 ℃,the rare earth segregation in all parts of the steel ingot decreases to varying degrees,among which the horizontal radius of the segregation zone with a mass fraction of 0.075% at the upper center is reduced by approximately 0.01 m. When the molten steel inlet flow rate increases from 11.66 t/min to 13.60 t/min,the central segregation is significantly reduced,with the horizontal coverage of the segregation zone above 0.06% at the top narrowed by about 0.02 m. When the mass fraction of rare earth addition amount increases from 0.048% to 0.08%,the horizontal radius of the top segregation zone widens by approximately 0.15 m.

Through thermodynamic calculations of carbon-oxygen reactions and theoretical analysis of CO production in molten steel, it is concluded that bubbles are not generated by the high oxygen enamel steel itself  during solidification. Therefore，during the continuous casting of high oxygen enamel steel, it is necessary to control the carbon content in the tundish flux and continuous casting mould power. By adopting pilot experiments and continuous casting production methods, it was found that as the active oxygen value in the high oxygen enamel steel increased, the total oxygen content also increased, the number of inclusions increased, and the maximum size of inclusions showed an increasing trend. When the active oxygen value reached 0.028 5%, the maximum size of inclusions exceeded 30 μm. The yield of alloy in the steel ingot decreased with the increased of active oxygen value in the molten steel. When the active oxygen value increased from 0.011 6% to 0.028 5%, the yield of Mn in the steel ingot decreased from 93% to 84.2%, and the yield of Nb in the steel ingot decreased from 76.2% to 68%.The inclusions in the high oxygen enamel steel continuous casting slab were spherical and mainly composed of oxides and manganese sulfide. Manganese oxide was the main component in the oxides, while manganese sulfide was distributed on the surface of the oxides. The above-mentioned inclusions were plastic inclusions that deform synchronously with the steel plate during the rolling process. After hot rolling, cold rolling, and enamel, high-quality continuous casting slab have good product performance.