Fluid flow, heat transfer and solidification of steel in the mold are so complex but crucial, determining the surface quality of the continuous casting slab. In the current study, a 2D numerical model was established ...Fluid flow, heat transfer and solidification of steel in the mold are so complex but crucial, determining the surface quality of the continuous casting slab. In the current study, a 2D numerical model was established by Fluent software to simulate the fluid flow, heat transfer and solidification of the steel in the mold. The VOF model and k-ε model were applied to simulate the flow field of the three phases(steel, slag and air), and solidification model was used to simulate the solidification process. The phenomena at the meniscus were also explored through interfacial tension between the liquid steel and slag as well as the mold oscillation. The model included a 20 mm thick mold to clarify the heat transfer and the temperature distribution of the mold. The simulation results show that the liquid steel flows as upper backflow and lower backflow in the mold, and that a small circulation forms at the meniscus. The liquid slag flows away from the corner at the meniscus or infiltrates into the gap between the mold and the shell with the mold oscillating at the negative strip stage or at the positive strip stage. The simulated pitch and the depth of oscillation marks approximate to the theoretical pitch and measured depth on the slab.展开更多
A heat transfer model on the solidification process has been established onthe basis of the technical conditions of the slab caster in No.3 steel works of Wuhan Iron & SteelCorporation, and the temperature field i...A heat transfer model on the solidification process has been established onthe basis of the technical conditions of the slab caster in No.3 steel works of Wuhan Iron & SteelCorporation, and the temperature field in the solidifying slab was calculated which was verified bythe measured slab surface temperature. The influences of the main operating factors includingcasting speed, spray cooling patterns, superheat of melt and slab size on the solidification processwere analyzed and the means of enhancing the slab temperature was brought forward. Raising thecasting speed to 1.3 m/min, controlling the flowrate of secondary cooling water and improving thecooling pattern at the lower segments of secondary cooling zone could improve the slab temperatureeffectively. And the increasing the superheat is adverse to the production of high temperature slab.展开更多
An unsteady, two-dimensional, explicitly solved fmite difference heat transfer model of a billet caster was presented to clarify the influence of the thermal conductivity of steel on model accuracy. Different approach...An unsteady, two-dimensional, explicitly solved fmite difference heat transfer model of a billet caster was presented to clarify the influence of the thermal conductivity of steel on model accuracy. Different approaches were utilized for calculating the thermal conductivity of solid, mushy and liquid steels. Model results predicted by these approaches were compared, and the advantages of advocated approaches were discussed. It is found that the approach for calculating the thermal conductivity of solid steel notably influences model predictions. Convection effects of liquid steel should be considered properly while calculating the thermal conductivity of mushy steel. Different values of the effective thermal conductivity of liquid steel adopted could partly be explained by the fact that different models adopted dissimilar ap- proaches for calculating the thermal conductivity of solid and mushy steels.展开更多
In order to study the effect of continuous casting process parameters on the shape of slab solidification end under non-uniform cooling,a solidification model of a continuous-cast slab with non-uniform cooling conditi...In order to study the effect of continuous casting process parameters on the shape of slab solidification end under non-uniform cooling,a solidification model of a continuous-cast slab with non-uniform cooling condition was established with ProCAST software.The model was verified by the results of nail shooting tests and the infrared temperature measurement equipment.Four characteristic parameters were defined to evaluate the uniformity of the shape of slab solidification end.The results showed that the nonuniformity at the beginning and end of solidification,the solidification end length,and the solidification unevenness increased with the rise of casting speed.For each 10°C increase of superheat,the solidification unevenness increased by about 0.022.However,the effect of superheat on the solidification end length can be ignored.The secondary cooling strength showed minimal effect on the nonuniformity at the beginning and end of solidification.With the increase in secondary cooling intensity,the solidification end length decreased,but the solidification unevenness increased.In addition,the central segregation of the slab produced with and without the mechanical soft reduction(MSR)process was investigated.The transverse flow of molten steel with low solid fraction influenced the central segregation morphology under MSR.展开更多
Continuous casting of steel involving different grades in the same casting sequence remains a challenge to billet caster operators. The intermixed composition obtained during the grade change does not meet the specifi...Continuous casting of steel involving different grades in the same casting sequence remains a challenge to billet caster operators. The intermixed composition obtained during the grade change does not meet the specification of either grade and must be downgraded. Incorrect identification of this intermixed region may result in non-conforming products reaching the customer. In this study, a numerical model based on CFD (computational fluid dynamics approach) has been developed which predicts the start and end of the intermixed composition and the tonnage to be downgraded under different casting conditions. This model was validated and the results were in good agreement with the actual plant data for a 6-strand billet caster at LD-1 of TATA Steel, India. This model is used to calculate transition tonnage for different scenarios, e.g. when one of the outermost strands is not functional or some combinations are not functional and varying casting speed during operation. Furthermore, impact of different design of baffles on performance of Tundish has been evaluated to find a way to reduce transition or intermixed composition.展开更多
基金supported by the National Natural Science Foundation of China(No.51504020,and No.51404019)Beijing Key Laboratory of Green Recycling and Extraction of Metals(GREM)+1 种基金the Laboratory of Green Process Metallurgy and Modeling(GPM2)the High Quality Steel Consortium(HQSC)at the School of Metallurgical and Ecological Engineering at University of Science and Technology Beijing(USTB),China
文摘Fluid flow, heat transfer and solidification of steel in the mold are so complex but crucial, determining the surface quality of the continuous casting slab. In the current study, a 2D numerical model was established by Fluent software to simulate the fluid flow, heat transfer and solidification of the steel in the mold. The VOF model and k-ε model were applied to simulate the flow field of the three phases(steel, slag and air), and solidification model was used to simulate the solidification process. The phenomena at the meniscus were also explored through interfacial tension between the liquid steel and slag as well as the mold oscillation. The model included a 20 mm thick mold to clarify the heat transfer and the temperature distribution of the mold. The simulation results show that the liquid steel flows as upper backflow and lower backflow in the mold, and that a small circulation forms at the meniscus. The liquid slag flows away from the corner at the meniscus or infiltrates into the gap between the mold and the shell with the mold oscillating at the negative strip stage or at the positive strip stage. The simulated pitch and the depth of oscillation marks approximate to the theoretical pitch and measured depth on the slab.
基金This work was financially sponsored by Jiangsu Youth Science Foundation (No.JDQ2001003).
文摘A heat transfer model on the solidification process has been established onthe basis of the technical conditions of the slab caster in No.3 steel works of Wuhan Iron & SteelCorporation, and the temperature field in the solidifying slab was calculated which was verified bythe measured slab surface temperature. The influences of the main operating factors includingcasting speed, spray cooling patterns, superheat of melt and slab size on the solidification processwere analyzed and the means of enhancing the slab temperature was brought forward. Raising thecasting speed to 1.3 m/min, controlling the flowrate of secondary cooling water and improving thecooling pattern at the lower segments of secondary cooling zone could improve the slab temperatureeffectively. And the increasing the superheat is adverse to the production of high temperature slab.
基金financially supported by the National Natural Science Foundation of China(No.51074019)
文摘An unsteady, two-dimensional, explicitly solved fmite difference heat transfer model of a billet caster was presented to clarify the influence of the thermal conductivity of steel on model accuracy. Different approaches were utilized for calculating the thermal conductivity of solid, mushy and liquid steels. Model results predicted by these approaches were compared, and the advantages of advocated approaches were discussed. It is found that the approach for calculating the thermal conductivity of solid steel notably influences model predictions. Convection effects of liquid steel should be considered properly while calculating the thermal conductivity of mushy steel. Different values of the effective thermal conductivity of liquid steel adopted could partly be explained by the fact that different models adopted dissimilar ap- proaches for calculating the thermal conductivity of solid and mushy steels.
基金financially supported by the National Natural Science Foundation of China(Nos.51774030 and U1860104)the Fundamental Research Funds for the Central Universities,China(No.N2025019).
文摘In order to study the effect of continuous casting process parameters on the shape of slab solidification end under non-uniform cooling,a solidification model of a continuous-cast slab with non-uniform cooling condition was established with ProCAST software.The model was verified by the results of nail shooting tests and the infrared temperature measurement equipment.Four characteristic parameters were defined to evaluate the uniformity of the shape of slab solidification end.The results showed that the nonuniformity at the beginning and end of solidification,the solidification end length,and the solidification unevenness increased with the rise of casting speed.For each 10°C increase of superheat,the solidification unevenness increased by about 0.022.However,the effect of superheat on the solidification end length can be ignored.The secondary cooling strength showed minimal effect on the nonuniformity at the beginning and end of solidification.With the increase in secondary cooling intensity,the solidification end length decreased,but the solidification unevenness increased.In addition,the central segregation of the slab produced with and without the mechanical soft reduction(MSR)process was investigated.The transverse flow of molten steel with low solid fraction influenced the central segregation morphology under MSR.
文摘Continuous casting of steel involving different grades in the same casting sequence remains a challenge to billet caster operators. The intermixed composition obtained during the grade change does not meet the specification of either grade and must be downgraded. Incorrect identification of this intermixed region may result in non-conforming products reaching the customer. In this study, a numerical model based on CFD (computational fluid dynamics approach) has been developed which predicts the start and end of the intermixed composition and the tonnage to be downgraded under different casting conditions. This model was validated and the results were in good agreement with the actual plant data for a 6-strand billet caster at LD-1 of TATA Steel, India. This model is used to calculate transition tonnage for different scenarios, e.g. when one of the outermost strands is not functional or some combinations are not functional and varying casting speed during operation. Furthermore, impact of different design of baffles on performance of Tundish has been evaluated to find a way to reduce transition or intermixed composition.
