To investigate the dissolution behaviors of Al_(2)O_(3)inclusions in CaO-5wt%MgO-SiO_(2)-30wt%Al_(2)O_(3)-TiO_(2)system ladle slags,confocal scanning laser microscopy was conducted on the slags with different TiO_(2)c...To investigate the dissolution behaviors of Al_(2)O_(3)inclusions in CaO-5wt%MgO-SiO_(2)-30wt%Al_(2)O_(3)-TiO_(2)system ladle slags,confocal scanning laser microscopy was conducted on the slags with different TiO_(2)contents(0-10wt%),and scanning electron microscopy was performed to study the interfacial reaction between Al_(2)O_(3)and this slag system.The results disclose that the dissolution of Al_(2)O_(3)inclusions does not result in the formation of new phases at the boundary between the slag and the inclusions.In TiO_(2)-bearing and TiO_(2)-free ladle slags,there is no difference in the dissolution mechanism of Al_(2)O_(3)inclusions at steelmaking temperatures.Boundary layer diffusion is found as the controlling step of the dissolution of Al_(2)O_(3),and the diffusion coefficient is in the range of 4.18×10^(-10)to 2.18×10^(-9)m^(2)/s at 1450-1500℃.Compared with the solubility of Al_(2)O_(3)in the slags,slag viscosity and temperature play a more profound role in the dissolution of Al_(2)O_(3)inclusions.A lower viscosity and a lower melting point of the slags are beneficial for the dissolution.Suitable addition of TiO_(2)(e.g.,5wt%)in ladle slags can enhance the dissolution of Al_(2)O_(3)inclusions because of the low viscosity and melting point of the slags,while excessive addition of TiO_(2)(e.g.,10wt%)shows the opposite trend.展开更多
Accurate prediction of molten steel temperature in the ladle furnace(LF)refining process has an important influence on the quality of molten steel and the control of steelmaking cost.Extensive research on establishing...Accurate prediction of molten steel temperature in the ladle furnace(LF)refining process has an important influence on the quality of molten steel and the control of steelmaking cost.Extensive research on establishing models to predict molten steel temperature has been conducted.However,most researchers focus solely on improving the accuracy of the model,neglecting its explainability.The present study aims to develop a high-precision and explainable model with improved reliability and transparency.The eXtreme gradient boosting(XGBoost)and light gradient boosting machine(LGBM)were utilized,along with bayesian optimization and grey wolf optimiz-ation(GWO),to establish the prediction model.Different performance evaluation metrics and graphical representations were applied to compare the optimal XGBoost and LGBM models obtained through varying hyperparameter optimization methods with the other models.The findings indicated that the GWO-LGBM model outperformed other methods in predicting molten steel temperature,with a high pre-diction accuracy of 89.35%within the error range of±5°C.The model’s learning/decision process was revealed,and the influence degree of different variables on the molten steel temperature was clarified using the tree structure visualization and SHapley Additive exPlana-tions(SHAP)analysis.Consequently,the explainability of the optimal GWO-LGBM model was enhanced,providing reliable support for prediction results.展开更多
The formation of slag eye in a gas stirred ladle was studied through cold models and industrial trials. In the cold model,water and sodium tungstate solution were employed to simulate liquid steel,and silicon oil was ...The formation of slag eye in a gas stirred ladle was studied through cold models and industrial trials. In the cold model,water and sodium tungstate solution were employed to simulate liquid steel,and silicon oil was employed to simulate slag. The simulation results revealed that the gas flow rate and bath height had strong effects on the slag eye size. In particular,the thickness of slag layer played a strong role in the slag eye size. In addition,the slag eye could not be formed when the thickness of the top layer was more than 4 cm in water-silicone oil model.Besides,the section area of vessel had a great impact on the slag eye size. Industrial trials results showed a similar trend that the gas flow rate was very significant on the slag eye size. The predictions of the existing models showed larger predictions deviations compared with the experimental data. Moreover,a new model without fitting parameters was developed based on force balance and mathematical derivation,and verified by the experimental data. The new model provides the prediction with small deviations by comparing with the data acquired from cold models and industrial trials.展开更多
To reduce the slag sticking onto the snorkel of the ladle during the ladle alloying treatment station （LATS） process, CaO- CaF2 （the mass ratio of CaO/CaF2 is 1：1） was employed as the modifier of the LATS refinin...To reduce the slag sticking onto the snorkel of the ladle during the ladle alloying treatment station （LATS） process, CaO- CaF2 （the mass ratio of CaO/CaF2 is 1：1） was employed as the modifier of the LATS refining ladle slag. The effect of CaO-CaF2 on the melting point, viscosity, and desulfurizing capability of the ladle slag was investigated. The melting point of the unmodified ladle slag is 1439℃. When adding 20wt% CaO-CaF2, the melting point is decreased to 1327℃. At 1500℃. the viscosity of the unmodified ladle slag is 6.5 Pa.s, which can be decreased lower than 2 Pa.s by adding more than 10wt% CaO-CaF2. The experimental results of desulfu- rization of the melts show that the desulfurizing power of the ladle slag can be enhanced by adding CaO-CaF2.展开更多
Damage reasons of purging plugs for refining ladle and research progress on thermal shock resistance of corundum- spinel purging plugs were summarized. Research achievements and application results of nonoxides bonded...Damage reasons of purging plugs for refining ladle and research progress on thermal shock resistance of corundum- spinel purging plugs were summarized. Research achievements and application results of nonoxides bonded corundum purging plugs for refining ladle were briefly reviewed. The further research and developing trend of purging plugs was proposed.展开更多
1 Scope This standard specifies the classification, technical requirements, test methods, inspection rules, marking, packing, transportation, storage and quality certificate of purging plugs and well blocks for refini...1 Scope This standard specifies the classification, technical requirements, test methods, inspection rules, marking, packing, transportation, storage and quality certificate of purging plugs and well blocks for refining ladle.展开更多
Carbon-free Al_(2)O_(3)-MgO dense bricks were produced by the pressing method,using tabular alumina,white fused alumina,alumina micro-powder as main raw materials,and inorganic powder as the binder.The comprehensive p...Carbon-free Al_(2)O_(3)-MgO dense bricks were produced by the pressing method,using tabular alumina,white fused alumina,alumina micro-powder as main raw materials,and inorganic powder as the binder.The comprehensive properties and performance in steel ladle side wall were made a comparison between Al_(2)O_(3)-MgO dense bricks and precast blocks.The results show that Al_(2)O_(3)-MgO dense bricks exhibit high dense structure and strength,as well as superior thermal shock resistance and better penetration and corrosion resistance to slag than precast blocks.While replacing precast blocks with dense bricks in 250 t steel ladle side wall in some domestic steel mills,the thickness of the metamorphic layer from slag penetration and the corrosion rate decrease evidently.The damage of dense bricks during service is mainly caused by the corrosion from molten steel and slag,and the structure spalling of the metamorphic layer also plays an important role.展开更多
The manufacture of clean steel needs high performance carbon-free bricks for ladle lining.Based on long term application experiences of the prefab Al_(2)O_(3)-MgO blocks,unburnt Al_(2)O_(3)-MgO brick has been develope...The manufacture of clean steel needs high performance carbon-free bricks for ladle lining.Based on long term application experiences of the prefab Al_(2)O_(3)-MgO blocks,unburnt Al_(2)O_(3)-MgO brick has been developed by pressing a mix of alumina,spinel and magnesia as major raw materials and Al_(2)O_(3)-MgO gel powder as binder.In addition to low open porosity and high strength,the unburnt Al_(2)O_(3)-MgO brick shows superior corrosion resistance and thermal shock resistance to the prefab block.Field trials in a 300t steel ladle have indicated the residual lining of unburnt Al_(2)O_(3)-MgO bricks showed smooth surface without large spalling and seldom steel infiltration,consequently longer service life than the prefab blocks.The reliable,unburnt Al_(2)O_(3)-MgO bricks have more advantages of high efficiency,energy-saving and eco-friendly production.It will be one of the best options for ladle lining in the manufacture of high-purity steel.展开更多
The metallurgical properties and fatigue life of bearing steel processed by electric furnace (EAF), ladle refining (LF-VD), continous casting (CC) and electroslag remelting (ESR) have been investigated. The main resul...The metallurgical properties and fatigue life of bearing steel processed by electric furnace (EAF), ladle refining (LF-VD), continous casting (CC) and electroslag remelting (ESR) have been investigated. The main results obtained are as follows: (1) Due to low oxygen content and dispersion inclusions in steel, the fatigue Life of LF-VD-IC or CC is three times as high as that of EAF steel; (2) The oxygen content in steel produced by CC process is about 9.0x10(-6), the carbon segregation (C/C(0)) is from 0.92 to 1.10 and the fatigue life of CC steel is equal to that of ladle refining ingot casting steel; (3) Although the amount of inclusion and oxygen in ESR steel is higher than that of LF-VD-IC or CC steel, the fatigue life of ESR steel is higher than that of the latter because of its fine and well dispersed inclusions.展开更多
A mathematical model which describes the fluid flow in a gas stirred original ladle and CAS OB ladle was introduced. The fluid field analysis was obtained through mathematical simulation. In order to decrease the lad...A mathematical model which describes the fluid flow in a gas stirred original ladle and CAS OB ladle was introduced. The fluid field analysis was obtained through mathematical simulation. In order to decrease the ladle refractory wearing and increase the heating speed of liquid steel, some measures should be adopted. The result shows that the flow fields in CAS OB ladle and original ladle are different. With a fixed gas flow rate, the flow field is related to the plug position and the snorkel depth. When the nozzle is located at 0 45 r , where r is the radius of ladle bottom, the fluid field predicted by water modeling is quite satisfactory for improving the quality of liquid steel.展开更多
As a functional metallurgical container for molten steel,refining ladle has a great influence on the smelting safety and quality of steel.The online monitoring of the residual thickness for ladle lining was applied to...As a functional metallurgical container for molten steel,refining ladle has a great influence on the smelting safety and quality of steel.The online monitoring of the residual thickness for ladle lining was applied to increase the smelting efficiency and safety.It is found that the ladle refractories show obvious discontinuous degradation characteristics through the monitoring data.Moreover,the degradation of low-carbon magnesia–carbon brick at slag line and corundum-based castable at steel bath was calculated according to the established corrosion model and crack propagation model,respectively.The discontinuous degradation mechanism of the ladle refractories is illustrated,which is of great significance to the optimal configuration of the ladle lining refractories.展开更多
Ti-stabilized 321 stainless steel was prepared using an electric arc furnace, argon oxygen decarburization (AOD) furnace, ladle furnace (LF), and continuous casting processes. In addition, the effect of refining proce...Ti-stabilized 321 stainless steel was prepared using an electric arc furnace, argon oxygen decarburization (AOD) furnace, ladle furnace (LF), and continuous casting processes. In addition, the effect of refining process and utilization of different slags on the evolution of inclusions, titanium yield, and oxygen content was systematically investigated by experimental and thermodynamic analysis. The results reveal that the total oxygen content (TO) and inclusion density decreased during the refining process. The spherical CaO–SiO2–Al2O3–MgO inclusions existed in the 321 stainless steel after the AOD process. Moreover, prior to the Ti addition, the spherical CaO–Al2O3–MgO–SiO2 inclusions were observed during LF refining pro-cess. However, Ti addition resulted in multilayer CaO–Al2O3–MgO–TiOx inclusions. Two different samples were prepared by conventional CaO–Al2O3-based slag (Heat-1) and -TiO2-rich CaO–Al2O3-based slag (Heat-2). The statistical analysis revealed that the density of inclusions and the -TiOx content in CaO–Al2O3–MgO–TiOx inclusions found in Heat-2 sample are much lower than those in the Heat-1 sample. Furthermore, the TO content and Ti yield during the LF refining process were controlled by using -TiO2-rich calcium aluminate synthetic slag. These results were consistent with the ion–molecule coexist-ence theory and FactSage?7.2 software calculations. When -TiO2-rich CaO–Al2O3-based slag was used, the -TiO2 activity of the slag increased, and the equilibrium oxygen content significantly decreased from the AOD to LF processes. Therefore, the higher -TiO2 activity of slag and lower equilibrium oxygen content suppressed the undesirable reactions between Ti and O.展开更多
The behavior of non-metallic inclusions in LCAK （low carbon aluminum killed） steel produced by BOF （basic oxygen furnace）-LF （ladle furnace） refining-FTSC （flexible thin slab continuous caster） production rout...The behavior of non-metallic inclusions in LCAK （low carbon aluminum killed） steel produced by BOF （basic oxygen furnace）-LF （ladle furnace） refining-FTSC （flexible thin slab continuous caster） production route was investigated. The results showed that, LF refining for LCAK steel could decrease the wT[o] significantly, and the inclusions were modified by Ca treatment, which prevented nozzle clogging efficiently. However, owing to the unstable casting condition in the earlier stage of casting, a severe reoxidation occurred, accompanied with mold slag entrapment. The transformation of non-metallic inclusions during the steelmaking process was Al2O3→MgO→Al2O3 type inclusion→MgO-Al2O3 O3-CaO type inclusion with a CaS ring, and the mechanism of the transformation was pro posed and discussed via thermodynamic and kinetic analysis. Besides, to avoid CaS precipitation, the product of W[Al] ×w3[S] in steel should be less than 2.0 × 10 10 at 1873 K, which remands higher desulfurization ratio during LF refining.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.U20A20272 and52074073)the Fundamental Research Funds for the Central Universities(No.2325035)。
文摘To investigate the dissolution behaviors of Al_(2)O_(3)inclusions in CaO-5wt%MgO-SiO_(2)-30wt%Al_(2)O_(3)-TiO_(2)system ladle slags,confocal scanning laser microscopy was conducted on the slags with different TiO_(2)contents(0-10wt%),and scanning electron microscopy was performed to study the interfacial reaction between Al_(2)O_(3)and this slag system.The results disclose that the dissolution of Al_(2)O_(3)inclusions does not result in the formation of new phases at the boundary between the slag and the inclusions.In TiO_(2)-bearing and TiO_(2)-free ladle slags,there is no difference in the dissolution mechanism of Al_(2)O_(3)inclusions at steelmaking temperatures.Boundary layer diffusion is found as the controlling step of the dissolution of Al_(2)O_(3),and the diffusion coefficient is in the range of 4.18×10^(-10)to 2.18×10^(-9)m^(2)/s at 1450-1500℃.Compared with the solubility of Al_(2)O_(3)in the slags,slag viscosity and temperature play a more profound role in the dissolution of Al_(2)O_(3)inclusions.A lower viscosity and a lower melting point of the slags are beneficial for the dissolution.Suitable addition of TiO_(2)(e.g.,5wt%)in ladle slags can enhance the dissolution of Al_(2)O_(3)inclusions because of the low viscosity and melting point of the slags,while excessive addition of TiO_(2)(e.g.,10wt%)shows the opposite trend.
基金financially supported by the National Natural Science Foundation of China(Nos.51974023 and 52374321)the funding of State Key Laboratory of Advanced Metallurgy,University of Science and Technology Beijing(No.41621005)the Youth Science and Technology Innovation Fund of Jianlong Group-University of Science and Technology Beijing(No.20231235).
文摘Accurate prediction of molten steel temperature in the ladle furnace(LF)refining process has an important influence on the quality of molten steel and the control of steelmaking cost.Extensive research on establishing models to predict molten steel temperature has been conducted.However,most researchers focus solely on improving the accuracy of the model,neglecting its explainability.The present study aims to develop a high-precision and explainable model with improved reliability and transparency.The eXtreme gradient boosting(XGBoost)and light gradient boosting machine(LGBM)were utilized,along with bayesian optimization and grey wolf optimiz-ation(GWO),to establish the prediction model.Different performance evaluation metrics and graphical representations were applied to compare the optimal XGBoost and LGBM models obtained through varying hyperparameter optimization methods with the other models.The findings indicated that the GWO-LGBM model outperformed other methods in predicting molten steel temperature,with a high pre-diction accuracy of 89.35%within the error range of±5°C.The model’s learning/decision process was revealed,and the influence degree of different variables on the molten steel temperature was clarified using the tree structure visualization and SHapley Additive exPlana-tions(SHAP)analysis.Consequently,the explainability of the optimal GWO-LGBM model was enhanced,providing reliable support for prediction results.
基金financially supported by National Natural Science Foundation of China(51534001,51604003)Natural Science Research Project of Anhui Province Universities(KJ2016A089)Youth Foundation of Anhui University and Technology(QZ201502)
文摘The formation of slag eye in a gas stirred ladle was studied through cold models and industrial trials. In the cold model,water and sodium tungstate solution were employed to simulate liquid steel,and silicon oil was employed to simulate slag. The simulation results revealed that the gas flow rate and bath height had strong effects on the slag eye size. In particular,the thickness of slag layer played a strong role in the slag eye size. In addition,the slag eye could not be formed when the thickness of the top layer was more than 4 cm in water-silicone oil model.Besides,the section area of vessel had a great impact on the slag eye size. Industrial trials results showed a similar trend that the gas flow rate was very significant on the slag eye size. The predictions of the existing models showed larger predictions deviations compared with the experimental data. Moreover,a new model without fitting parameters was developed based on force balance and mathematical derivation,and verified by the experimental data. The new model provides the prediction with small deviations by comparing with the data acquired from cold models and industrial trials.
基金This study was financially supported by Baosteel, College Natural Science Research Project of Jiangsu Province (No. 04KJB430022,05KJD450043)the National Natural Science Foundation of China (No.50474037)
文摘To reduce the slag sticking onto the snorkel of the ladle during the ladle alloying treatment station （LATS） process, CaO- CaF2 （the mass ratio of CaO/CaF2 is 1：1） was employed as the modifier of the LATS refining ladle slag. The effect of CaO-CaF2 on the melting point, viscosity, and desulfurizing capability of the ladle slag was investigated. The melting point of the unmodified ladle slag is 1439℃. When adding 20wt% CaO-CaF2, the melting point is decreased to 1327℃. At 1500℃. the viscosity of the unmodified ladle slag is 6.5 Pa.s, which can be decreased lower than 2 Pa.s by adding more than 10wt% CaO-CaF2. The experimental results of desulfu- rization of the melts show that the desulfurizing power of the ladle slag can be enhanced by adding CaO-CaF2.
基金National Science Foundation of China ( No.51032007 and No.U1204505) for supporting this work
文摘Damage reasons of purging plugs for refining ladle and research progress on thermal shock resistance of corundum- spinel purging plugs were summarized. Research achievements and application results of nonoxides bonded corundum purging plugs for refining ladle were briefly reviewed. The further research and developing trend of purging plugs was proposed.
文摘1 Scope This standard specifies the classification, technical requirements, test methods, inspection rules, marking, packing, transportation, storage and quality certificate of purging plugs and well blocks for refining ladle.
文摘Carbon-free Al_(2)O_(3)-MgO dense bricks were produced by the pressing method,using tabular alumina,white fused alumina,alumina micro-powder as main raw materials,and inorganic powder as the binder.The comprehensive properties and performance in steel ladle side wall were made a comparison between Al_(2)O_(3)-MgO dense bricks and precast blocks.The results show that Al_(2)O_(3)-MgO dense bricks exhibit high dense structure and strength,as well as superior thermal shock resistance and better penetration and corrosion resistance to slag than precast blocks.While replacing precast blocks with dense bricks in 250 t steel ladle side wall in some domestic steel mills,the thickness of the metamorphic layer from slag penetration and the corrosion rate decrease evidently.The damage of dense bricks during service is mainly caused by the corrosion from molten steel and slag,and the structure spalling of the metamorphic layer also plays an important role.
文摘The manufacture of clean steel needs high performance carbon-free bricks for ladle lining.Based on long term application experiences of the prefab Al_(2)O_(3)-MgO blocks,unburnt Al_(2)O_(3)-MgO brick has been developed by pressing a mix of alumina,spinel and magnesia as major raw materials and Al_(2)O_(3)-MgO gel powder as binder.In addition to low open porosity and high strength,the unburnt Al_(2)O_(3)-MgO brick shows superior corrosion resistance and thermal shock resistance to the prefab block.Field trials in a 300t steel ladle have indicated the residual lining of unburnt Al_(2)O_(3)-MgO bricks showed smooth surface without large spalling and seldom steel infiltration,consequently longer service life than the prefab blocks.The reliable,unburnt Al_(2)O_(3)-MgO bricks have more advantages of high efficiency,energy-saving and eco-friendly production.It will be one of the best options for ladle lining in the manufacture of high-purity steel.
文摘The metallurgical properties and fatigue life of bearing steel processed by electric furnace (EAF), ladle refining (LF-VD), continous casting (CC) and electroslag remelting (ESR) have been investigated. The main results obtained are as follows: (1) Due to low oxygen content and dispersion inclusions in steel, the fatigue Life of LF-VD-IC or CC is three times as high as that of EAF steel; (2) The oxygen content in steel produced by CC process is about 9.0x10(-6), the carbon segregation (C/C(0)) is from 0.92 to 1.10 and the fatigue life of CC steel is equal to that of ladle refining ingot casting steel; (3) Although the amount of inclusion and oxygen in ESR steel is higher than that of LF-VD-IC or CC steel, the fatigue life of ESR steel is higher than that of the latter because of its fine and well dispersed inclusions.
基金Item Sponsored by National Natural Science Foundation of China(59874018)
文摘A mathematical model which describes the fluid flow in a gas stirred original ladle and CAS OB ladle was introduced. The fluid field analysis was obtained through mathematical simulation. In order to decrease the ladle refractory wearing and increase the heating speed of liquid steel, some measures should be adopted. The result shows that the flow fields in CAS OB ladle and original ladle are different. With a fixed gas flow rate, the flow field is related to the plug position and the snorkel depth. When the nozzle is located at 0 45 r , where r is the radius of ladle bottom, the fluid field predicted by water modeling is quite satisfactory for improving the quality of liquid steel.
基金This work was financially supported by the National Natural Science Foundation of China(Grant Nos.U1908227,U1860205,and U20A20270)Key Program of Natural Science Foundation of Hubei Province(2021CFA071)the Special Project of Central Government for Local Science and Technology Development of Hubei Province(2019ZYYD076).
文摘As a functional metallurgical container for molten steel,refining ladle has a great influence on the smelting safety and quality of steel.The online monitoring of the residual thickness for ladle lining was applied to increase the smelting efficiency and safety.It is found that the ladle refractories show obvious discontinuous degradation characteristics through the monitoring data.Moreover,the degradation of low-carbon magnesia–carbon brick at slag line and corundum-based castable at steel bath was calculated according to the established corrosion model and crack propagation model,respectively.The discontinuous degradation mechanism of the ladle refractories is illustrated,which is of great significance to the optimal configuration of the ladle lining refractories.
基金The authors gratcfully acknowledge the sup-port of the National Natural Science Foundation of China(Grant No.51374020)the State Key Laboratory of Advanced Metallurgy at theUniversity of Science and Technology Beijing(USTB)the JiuquanIron and Steel Group Corporation.
文摘Ti-stabilized 321 stainless steel was prepared using an electric arc furnace, argon oxygen decarburization (AOD) furnace, ladle furnace (LF), and continuous casting processes. In addition, the effect of refining process and utilization of different slags on the evolution of inclusions, titanium yield, and oxygen content was systematically investigated by experimental and thermodynamic analysis. The results reveal that the total oxygen content (TO) and inclusion density decreased during the refining process. The spherical CaO–SiO2–Al2O3–MgO inclusions existed in the 321 stainless steel after the AOD process. Moreover, prior to the Ti addition, the spherical CaO–Al2O3–MgO–SiO2 inclusions were observed during LF refining pro-cess. However, Ti addition resulted in multilayer CaO–Al2O3–MgO–TiOx inclusions. Two different samples were prepared by conventional CaO–Al2O3-based slag (Heat-1) and -TiO2-rich CaO–Al2O3-based slag (Heat-2). The statistical analysis revealed that the density of inclusions and the -TiOx content in CaO–Al2O3–MgO–TiOx inclusions found in Heat-2 sample are much lower than those in the Heat-1 sample. Furthermore, the TO content and Ti yield during the LF refining process were controlled by using -TiO2-rich calcium aluminate synthetic slag. These results were consistent with the ion–molecule coexist-ence theory and FactSage?7.2 software calculations. When -TiO2-rich CaO–Al2O3-based slag was used, the -TiO2 activity of the slag increased, and the equilibrium oxygen content significantly decreased from the AOD to LF processes. Therefore, the higher -TiO2 activity of slag and lower equilibrium oxygen content suppressed the undesirable reactions between Ti and O.
基金Item Sponsored by National Key Technology Research and Development Programin 11th Five-Year Plan of China(2006BAE03A13)
文摘The behavior of non-metallic inclusions in LCAK （low carbon aluminum killed） steel produced by BOF （basic oxygen furnace）-LF （ladle furnace） refining-FTSC （flexible thin slab continuous caster） production route was investigated. The results showed that, LF refining for LCAK steel could decrease the wT[o] significantly, and the inclusions were modified by Ca treatment, which prevented nozzle clogging efficiently. However, owing to the unstable casting condition in the earlier stage of casting, a severe reoxidation occurred, accompanied with mold slag entrapment. The transformation of non-metallic inclusions during the steelmaking process was Al2O3→MgO→Al2O3 type inclusion→MgO-Al2O3 O3-CaO type inclusion with a CaS ring, and the mechanism of the transformation was pro posed and discussed via thermodynamic and kinetic analysis. Besides, to avoid CaS precipitation, the product of W[Al] ×w3[S] in steel should be less than 2.0 × 10 10 at 1873 K, which remands higher desulfurization ratio during LF refining.
