The purpose of this study is to predict the morphologies in the solidification process for Cu-0.6Cr(mass fraction,%)alloy by vacuum continuous casting(VCC)and verify its accuracy by the observed experimental results.I...The purpose of this study is to predict the morphologies in the solidification process for Cu-0.6Cr(mass fraction,%)alloy by vacuum continuous casting(VCC)and verify its accuracy by the observed experimental results.In numerical simulation aspect, finite difference(FD)method and modified cellular automaton(MCA)model were used to simulate the macro-temperature field, micro-concentration field,nucleation and grain growth of Cu-0.6Cr alloy using real data from actual casting operations.From the observed casting experiment,the preliminary grain morphologies are the directional columnar grains by the VCC process.The solidification morphologies by MCAFD model are in agreement with the result of actual casting experiment well.展开更多
A 3D coupling mathematical simulation program of the fluid flow, thermal transfer and solidification was developed based on the slab continuous casting process. Some characteristics such as fluid flow, solidification ...A 3D coupling mathematical simulation program of the fluid flow, thermal transfer and solidification was developed based on the slab continuous casting process. Some characteristics such as fluid flow, solidification and temperature distribution near the submerged entry nozzle （SEN） and the corner of the mold were simulated and analyzed. The result of the calculation indicates that the flow of molten metal forms two big cycling zones in the mold after it flows out of the SEN, and the temperature at the center of the two zones is relatively low. Moreover, there is a small narrow cycling zone near the narrow side of the mold due to casting. The velocity of the surface flow, the turbulent kinetic energy and the F value might reveal the relationship between the fluctuation of meniscus and the quality of the slab to some degree.展开更多
A mathematical model for heat transfer during solidification in continuous casting of automobile steel, was established on researching under the influence of the solidifying process of bloom quality of CCM in the EAF ...A mathematical model for heat transfer during solidification in continuous casting of automobile steel, was established on researching under the influence of the solidifying process of bloom quality of CCM in the EAF steelmaking shop, at Shijiazhuang Iron and Steel Co. Ltd. Several steel grades were chosen to research, such as, 40Cr and 42CrMo. According to the results of the high temperature mechanical property tests of blooms, the respective temperature curves for controlling the solidification of different steels were acquired, and a simulating software was developed. The model was verified using two methods, which were bloom pinshooting and surface strand temperature measuring experiments. The model provided references for research on the solidifying process and optimization of a secondary cooling system for automobile steel. Moreover, it was already applied to real production. The calculated temperature distribution and solidification trend of blooms had offered a reliable theory for optimizing the solidifying process of blooms, increasing withdrawal speed, and improving bloom quality. Meanwhile, a new secondary cooling system was designed to optimize a secondary cooling water distribution, including choice and arrangements of nozzles, calculation of cooling water quantity, and so on. 2008 University of Science and Technology Beijing. All rights reserved.展开更多
In order to quantify the understanding of crack formation in Horizontal Continuous Casting billet.the two-dimensional unsteady state mathematical model for heat transfer and elas-toplastic stress model have been estab...In order to quantify the understanding of crack formation in Horizontal Continuous Casting billet.the two-dimensional unsteady state mathematical model for heat transfer and elas-toplastic stress model have been established.Using these models to calculate the thermal stress which occurred both during surface reheating of 150× 150 mm billet which is just taken out of mold and during temperature drop in billet centre near the end of solidification,the reasonable crack formation criteria for about 0.45%carbon steel have been proposed as follows:In high temperature brittle zone higher than 1300℃,the critical tensile strength is about 170-390 N/cm^2,the critical strain to fracture is about 0.10%- 0.24%.展开更多
To simulate the phenomena in the mold region of continuous casting by coupling fluid flow and solidification, a three-dimensional mathematical model has been developed based on the K-ε turbulence equations and the SI...To simulate the phenomena in the mold region of continuous casting by coupling fluid flow and solidification, a three-dimensional mathematical model has been developed based on the K-ε turbulence equations and the SIMPLER algorithm. A pseudo source term was introduced into the energy equation to account for the latent heat and kinetic energy. The fluid flow in the mushy zone was calculated by defining the fluid viscosity as a function of the solid fraction in the mushy zone. Fine meshes in the solid region improve convergence and reduce iteration time. Comparison of the fluid flow and temperature distribution with and without solidification shows that although the solid shell in the mold is thin, it still greatly affects the flow pattern. The numerical results obtained provide details of the fluid flow and solidification phenomena which can be used to optimize the nozzle structure and other process parameters in continuous casting.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
A general mathematical model and boundary condition applicable to momentum and heat transfer in the semisolid continuous casting(SCC) process was established. Using the model, the numerical simulation of the momentum ...A general mathematical model and boundary condition applicable to momentum and heat transfer in the semisolid continuous casting(SCC) process was established. Using the model, the numerical simulation of the momentum and heat transfer of molten metal was carried out in the SCC system. The obtained results fit well with the measured ones. Moreover, using the numerical simulating software, the effect of various factors on breakout and breakage was explored. The obtained results show that heat flow density of copper mold and the withdrawal beginning time are two major influencing factors. The larger the heat flow density of copper mold, or the shorter the withdrawal beginning time, the more stable the semisolid continuous casting process. [展开更多
A two-dimensional model was applied to investigate the influence of the interfacial tension between the steel and the slag on the behavior of the meniscus in continuous casting mold of slab.The shape of the meniscus a...A two-dimensional model was applied to investigate the influence of the interfacial tension between the steel and the slag on the behavior of the meniscus in continuous casting mold of slab.The shape of the meniscus and phenomena near the meniscus were revealed,and the profile of the slag rim and the depth of the solidified meniscus and oscillation marks with different interfacial tension of the steel and slag were compared.With the increase in the interfacial tension,the size of the curved meniscus increased,while the curvature and the height of the local meniscus close to the mold decreased.Besides,the thickness of the slag rim,solid slag and total slag near the meniscus had the tendency to increase,and the bottom of the slag rim became lower and thicker.With the increase in the interfacial tension from 0.1 to 2.5 N/m,the location of the largest heat flux near the meniscus decreased from 10.0 to 2.5 mm above the initial level of the steel,and the largest heat flux was within 3.52-4.58 MW/m^(2).Meanwhile,the largest depth of the solidified meniscus decreased from 3.3 to 2.3 mm,and the depth of oscillation marks decreased,which was conducive to the shallow hook at the subsurface of the slab,and the improvement of surface cleanliness of 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
To study fluctuations of the free surface of liquid steel in the mold,two different models with the same casting conditions but different thicknesses were employed to analyze the hydrodynamic behavior at the top of th...To study fluctuations of the free surface of liquid steel in the mold,two different models with the same casting conditions but different thicknesses were employed to analyze the hydrodynamic behavior at the top of the mold.The first model was a standard thickness slab,and the second had a thickness three times wider.It is found with the second model that above the plane formed by the steel jets,it is possible to observe four three-dimensional vortexes that interact with the submerged entry nozzle（SEN）and mold walls.By using a biphasic model to simulate the interface between the liquid and air inside the mold,the flow asymmetry and the fluctuations of the free surface can be clearly observed.展开更多
文摘The purpose of this study is to predict the morphologies in the solidification process for Cu-0.6Cr(mass fraction,%)alloy by vacuum continuous casting(VCC)and verify its accuracy by the observed experimental results.In numerical simulation aspect, finite difference(FD)method and modified cellular automaton(MCA)model were used to simulate the macro-temperature field, micro-concentration field,nucleation and grain growth of Cu-0.6Cr alloy using real data from actual casting operations.From the observed casting experiment,the preliminary grain morphologies are the directional columnar grains by the VCC process.The solidification morphologies by MCAFD model are in agreement with the result of actual casting experiment well.
文摘A 3D coupling mathematical simulation program of the fluid flow, thermal transfer and solidification was developed based on the slab continuous casting process. Some characteristics such as fluid flow, solidification and temperature distribution near the submerged entry nozzle （SEN） and the corner of the mold were simulated and analyzed. The result of the calculation indicates that the flow of molten metal forms two big cycling zones in the mold after it flows out of the SEN, and the temperature at the center of the two zones is relatively low. Moreover, there is a small narrow cycling zone near the narrow side of the mold due to casting. The velocity of the surface flow, the turbulent kinetic energy and the F value might reveal the relationship between the fluctuation of meniscus and the quality of the slab to some degree.
基金the New Century Excellent Talents Program of the Ministry of Education of China(NCET-2007-0067).
文摘A mathematical model for heat transfer during solidification in continuous casting of automobile steel, was established on researching under the influence of the solidifying process of bloom quality of CCM in the EAF steelmaking shop, at Shijiazhuang Iron and Steel Co. Ltd. Several steel grades were chosen to research, such as, 40Cr and 42CrMo. According to the results of the high temperature mechanical property tests of blooms, the respective temperature curves for controlling the solidification of different steels were acquired, and a simulating software was developed. The model was verified using two methods, which were bloom pinshooting and surface strand temperature measuring experiments. The model provided references for research on the solidifying process and optimization of a secondary cooling system for automobile steel. Moreover, it was already applied to real production. The calculated temperature distribution and solidification trend of blooms had offered a reliable theory for optimizing the solidifying process of blooms, increasing withdrawal speed, and improving bloom quality. Meanwhile, a new secondary cooling system was designed to optimize a secondary cooling water distribution, including choice and arrangements of nozzles, calculation of cooling water quantity, and so on. 2008 University of Science and Technology Beijing. All rights reserved.
文摘In order to quantify the understanding of crack formation in Horizontal Continuous Casting billet.the two-dimensional unsteady state mathematical model for heat transfer and elas-toplastic stress model have been established.Using these models to calculate the thermal stress which occurred both during surface reheating of 150× 150 mm billet which is just taken out of mold and during temperature drop in billet centre near the end of solidification,the reasonable crack formation criteria for about 0.45%carbon steel have been proposed as follows:In high temperature brittle zone higher than 1300℃,the critical tensile strength is about 170-390 N/cm^2,the critical strain to fracture is about 0.10%- 0.24%.
基金Supported by the National Natural Science Foundationof China-Bao Steel Conjunct Foundation ( No.5 0 1 74 0 31 )
文摘To simulate the phenomena in the mold region of continuous casting by coupling fluid flow and solidification, a three-dimensional mathematical model has been developed based on the K-ε turbulence equations and the SIMPLER algorithm. A pseudo source term was introduced into the energy equation to account for the latent heat and kinetic energy. The fluid flow in the mushy zone was calculated by defining the fluid viscosity as a function of the solid fraction in the mushy zone. Fine meshes in the solid region improve convergence and reduce iteration time. Comparison of the fluid flow and temperature distribution with and without solidification shows that although the solid shell in the mold is thin, it still greatly affects the flow pattern. The numerical results obtained provide details of the fluid flow and solidification phenomena which can be used to optimize the nozzle structure and other process parameters in continuous casting.
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.
文摘A general mathematical model and boundary condition applicable to momentum and heat transfer in the semisolid continuous casting(SCC) process was established. Using the model, the numerical simulation of the momentum and heat transfer of molten metal was carried out in the SCC system. The obtained results fit well with the measured ones. Moreover, using the numerical simulating software, the effect of various factors on breakout and breakage was explored. The obtained results show that heat flow density of copper mold and the withdrawal beginning time are two major influencing factors. The larger the heat flow density of copper mold, or the shorter the withdrawal beginning time, the more stable the semisolid continuous casting process. [
基金The authors are grateful for support from the National Natural Science Foundation of China(Grant Nos.52004045,52074054 and U20A20270)the Fundamental Research Funds for the Central Universities(Grant No.2022CDJXY-011)and College of Materials Science and Engineering and Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and Advanced Materials at Chongqing University,China.
文摘A two-dimensional model was applied to investigate the influence of the interfacial tension between the steel and the slag on the behavior of the meniscus in continuous casting mold of slab.The shape of the meniscus and phenomena near the meniscus were revealed,and the profile of the slag rim and the depth of the solidified meniscus and oscillation marks with different interfacial tension of the steel and slag were compared.With the increase in the interfacial tension,the size of the curved meniscus increased,while the curvature and the height of the local meniscus close to the mold decreased.Besides,the thickness of the slag rim,solid slag and total slag near the meniscus had the tendency to increase,and the bottom of the slag rim became lower and thicker.With the increase in the interfacial tension from 0.1 to 2.5 N/m,the location of the largest heat flux near the meniscus decreased from 10.0 to 2.5 mm above the initial level of the steel,and the largest heat flux was within 3.52-4.58 MW/m^(2).Meanwhile,the largest depth of the solidified meniscus decreased from 3.3 to 2.3 mm,and the depth of oscillation marks decreased,which was conducive to the shallow hook at the subsurface of the slab,and the improvement of surface cleanliness of 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support by Universidad Autonoma Metropolitana (Nos.2231207 and 2270303)Sistema Nacional de Investigadores (SNI-CONACYT)
文摘To study fluctuations of the free surface of liquid steel in the mold,two different models with the same casting conditions but different thicknesses were employed to analyze the hydrodynamic behavior at the top of the mold.The first model was a standard thickness slab,and the second had a thickness three times wider.It is found with the second model that above the plane formed by the steel jets,it is possible to observe four three-dimensional vortexes that interact with the submerged entry nozzle（SEN）and mold walls.By using a biphasic model to simulate the interface between the liquid and air inside the mold,the flow asymmetry and the fluctuations of the free surface can be clearly observed.
