Fluctuation of molten steel level in continuous casting process is a critical issue. The analytic function for the liquid steel surface stability index( F) of the continuous casting slab mold under the action of elect...Fluctuation of molten steel level in continuous casting process is a critical issue. The analytic function for the liquid steel surface stability index( F) of the continuous casting slab mold under the action of electromagnetic stirring was derived. The effects on the F value of the electromagnetic field,casting mold,submerged entry nozzle,and casting speed were observed,and the stability of the process parameters of a practical continuous casting system was evaluated. The main results generated are as follows:①Based on the free flow jet theory,a formula is established for the level stability index of continuous casting slab mold under electromagnetic stirring.②According to the results of calculation,the various parameters in decreasing order of the magnitude of their influence are magnetic flux density,nozzle submersion depth,casting speed,slab width,stirring current frequency,and nozzle side-hole inclination angle.③For practical continuous casting with a slab thickness of 230 mm,the calculated F values are between 3 and 5 for different matches between slab width and casting speed,but the parameter optimization space is much larger for wider slab widths and lower casting speeds.展开更多
A magnetic and temperature field-coupled mathematical model is proposed to calculate the induction heating process of a discard substitution block for billet hot extrusion process. The mathematical model is validated ...A magnetic and temperature field-coupled mathematical model is proposed to calculate the induction heating process of a discard substitution block for billet hot extrusion process. The mathematical model is validated by comparing simulation results with temperature measurements recorded during physical modeling. Based on systematical analysis of calculation results, a quantitative sawtooth induction power curve was proposed to realize the aim of achieving the best distributed temperature field in the block within the shortest induction time.展开更多
Owing to the development of new products and higher requirement of product properties, the current existing induction heating technology of Baosteel can no longer satisfy the new requirements of the product line. Cont...Owing to the development of new products and higher requirement of product properties, the current existing induction heating technology of Baosteel can no longer satisfy the new requirements of the product line. Control of the induction heating temperature to an appropriate value is a key consideration in induction heating technology. To obtain acculturated temperatures, investigations were focused on the parameters of an induction heating system, including those of induction heating equipment and heating processes. In these investigations, computer simulation was used to model the induction heating process, followed by physical experimentation to verify and improve the simulation model; finally, optimized induction heating parameters were suggested. The use of computer simulations dramatically decreased physical experimental times, and the computed heating parameters were used to guide the physical experimentation and design of the product line ; this increased the efficiency of subsequent investigations. This study focuses on the development of induction heating technology in Baosteel, which includes the overall induction heating technology used in manufacturing backup rollers and in the thermomechanical control process.展开更多
A mathematical model of the transient electro-thermal coupling of the induction heating of a magnesiumalloy round billet is established herein. The heating curve and temperature distribution characteristics of a magne...A mathematical model of the transient electro-thermal coupling of the induction heating of a magnesiumalloy round billet is established herein. The heating curve and temperature distribution characteristics of a magnesium alloy were calculated during induction heating under different parameters. Factors such as the number of coil turns and the cooling conditions were analyzed. A method for optimizing the temperature control mode and coil length of the magnesium-alloy round billet is proposed. The length of the coil and corresponding heating mode are determined through the coil length ratio( CLR),which provides a theoretical basis for the optimization of the magnesium-alloy round billet's extrusion.展开更多
This study established a three-dimensional mathematical model to determine the fluid flow in a slab continuous casting mold under an electromagnetic stirring force. The flow structure and distribution were studied wit...This study established a three-dimensional mathematical model to determine the fluid flow in a slab continuous casting mold under an electromagnetic stirring force. The flow structure and distribution were studied with respect to different continuous casting parameters and stirring current. Based on the calculation results, the mold flux entrapment index in free surface and velocity uniformity index were used to evaluate the flow field in the mold. The theoretical basis for the optimization of the flow field structure was provided. The study also suggested an optimization method for electromagnetic stirring parameters.展开更多
A physical model with mercury as analog was developed to investigate the influences of electromagnetic stirring（EMS） on flow field in slab continuous casting when the submerged entry nozzle（SEN） was clogged with d...A physical model with mercury as analog was developed to investigate the influences of electromagnetic stirring（EMS） on flow field in slab continuous casting when the submerged entry nozzle（SEN） was clogged with different clogging rates（0,10% ,25% ,and 50% ）. The flow field in mold under different EMS currents（0, 40 A, and 60 A） was measured by an ultrasonic Doppler velocimeter. The results proved that the flow field in the mold was a typical double roll structure under non-clogging SEN. As the SEN clogging rate increased, the flow field structure was transformed from a double roll to asymmetry flow. When the clogging rate reached 50%, the up circulation disappeared on the clogged side. The zone under the meniscus near the narrow face was a non-flowing area. EMS could correct bias flow caused by SEN clogging and improve the symmetry of the flow field during SEN clogging.展开更多
To address the phenomenon of sparking during the edge induction heating process in hot strip mills,this paper uses numerical simulation to systematically investigate the key factors influencing sparking and their effe...To address the phenomenon of sparking during the edge induction heating process in hot strip mills,this paper uses numerical simulation to systematically investigate the key factors influencing sparking and their effects.The distribution of induced current density in the steel plate above roller conveyor table during the heating process is calculated and compared under different conditions,including the relative positions of the steel plate and induction coil,the width of the steel plate,and changes in load. The results show that when a narrow steel plate is heated or the steel plate shifts to the side of the induction coil,sparking between the steel plate and roller conveyor is more likely to occur.展开更多
Through physical modeling and numerical simulation,the flow field in a slab continuous casting mold with electromagnetic stirring is measured under different casting parameters and stirring currents. To qualitatively ...Through physical modeling and numerical simulation,the flow field in a slab continuous casting mold with electromagnetic stirring is measured under different casting parameters and stirring currents. To qualitatively evaluate the flow field in the mold, two indexes,i, e., mold flux entrapment and velocity uniformity, are proposed. Based on these two indexes, some optimized stirring parameters under different casting conditions can be determined.展开更多
Based on the modified Scheil model of solute redistribution,the effects of solidification rate,molten steel flow,and alloy composition on solute macrosegregation during the solidification of carbon steel continuous ca...Based on the modified Scheil model of solute redistribution,the effects of solidification rate,molten steel flow,and alloy composition on solute macrosegregation during the solidification of carbon steel continuous casting billet are calculated and analyzed. The formation mechanism of "white band "segregation under the condition of electromagnetic stirring is also involved,and some practical countermeasures to restrain the central segregation are suggested. The results show that the modified Scheil model can be applied to predict and analyze the macrosegregation of casting slab effectively. The ratio vx/R of the flow velocity of molten steel to solidification rate has decisive formations of segregation such as linear,V,and "white band"types. It is an effective way to select sufficient terminal cooling and reasonable electromagnetic stirring in order to decrease macrosegregation in the slab. The concept of the characteristic distance of solute enrichment layer can drastically simplify the calculation of solute redistribution at the solid/liquid interface of various elements in carbon steel.展开更多
Using computer simulation and test measurements,the relationship between the electromagnetic properties of an electromagnetic stirring roller and the roller structure parameters was analyzed and compared. The distribu...Using computer simulation and test measurements,the relationship between the electromagnetic properties of an electromagnetic stirring roller and the roller structure parameters was analyzed and compared. The distribution of the magnetic field,magnitude of the electromagnetic force,and matched-load characteristics were systematically investigated at different parameter values for the induction coils,iron core,shield,and roller sleeve.The results indicate that the change in the electromagnetic force with stirring frequency is non-linear and has a maximum value higher than 10 Hz;the electromagnetic force largely depends on the diameter of the core;and there is a mutual restriction relationship between the two-phase imbalance and the electromagnetic force.展开更多
Electromagnetic metallurgy is a technology that achieves molten metal stirring or transportation without contact by electromagnetic force or eddy current, as well as metal heat treatment by induction and diabatic heat...Electromagnetic metallurgy is a technology that achieves molten metal stirring or transportation without contact by electromagnetic force or eddy current, as well as metal heat treatment by induction and diabatic heating, thus to control all kinds of transitions in the metallurgical process efficiently, optimize the internal material structure and improve product quality.展开更多
文摘Fluctuation of molten steel level in continuous casting process is a critical issue. The analytic function for the liquid steel surface stability index( F) of the continuous casting slab mold under the action of electromagnetic stirring was derived. The effects on the F value of the electromagnetic field,casting mold,submerged entry nozzle,and casting speed were observed,and the stability of the process parameters of a practical continuous casting system was evaluated. The main results generated are as follows:①Based on the free flow jet theory,a formula is established for the level stability index of continuous casting slab mold under electromagnetic stirring.②According to the results of calculation,the various parameters in decreasing order of the magnitude of their influence are magnetic flux density,nozzle submersion depth,casting speed,slab width,stirring current frequency,and nozzle side-hole inclination angle.③For practical continuous casting with a slab thickness of 230 mm,the calculated F values are between 3 and 5 for different matches between slab width and casting speed,but the parameter optimization space is much larger for wider slab widths and lower casting speeds.
基金financially supported by National Science Foundation of China ( NO. 51274137 and NO. 11372174)
文摘A magnetic and temperature field-coupled mathematical model is proposed to calculate the induction heating process of a discard substitution block for billet hot extrusion process. The mathematical model is validated by comparing simulation results with temperature measurements recorded during physical modeling. Based on systematical analysis of calculation results, a quantitative sawtooth induction power curve was proposed to realize the aim of achieving the best distributed temperature field in the block within the shortest induction time.
文摘Owing to the development of new products and higher requirement of product properties, the current existing induction heating technology of Baosteel can no longer satisfy the new requirements of the product line. Control of the induction heating temperature to an appropriate value is a key consideration in induction heating technology. To obtain acculturated temperatures, investigations were focused on the parameters of an induction heating system, including those of induction heating equipment and heating processes. In these investigations, computer simulation was used to model the induction heating process, followed by physical experimentation to verify and improve the simulation model; finally, optimized induction heating parameters were suggested. The use of computer simulations dramatically decreased physical experimental times, and the computed heating parameters were used to guide the physical experimentation and design of the product line ; this increased the efficiency of subsequent investigations. This study focuses on the development of induction heating technology in Baosteel, which includes the overall induction heating technology used in manufacturing backup rollers and in the thermomechanical control process.
文摘A mathematical model of the transient electro-thermal coupling of the induction heating of a magnesiumalloy round billet is established herein. The heating curve and temperature distribution characteristics of a magnesium alloy were calculated during induction heating under different parameters. Factors such as the number of coil turns and the cooling conditions were analyzed. A method for optimizing the temperature control mode and coil length of the magnesium-alloy round billet is proposed. The length of the coil and corresponding heating mode are determined through the coil length ratio( CLR),which provides a theoretical basis for the optimization of the magnesium-alloy round billet's extrusion.
文摘This study established a three-dimensional mathematical model to determine the fluid flow in a slab continuous casting mold under an electromagnetic stirring force. The flow structure and distribution were studied with respect to different continuous casting parameters and stirring current. Based on the calculation results, the mold flux entrapment index in free surface and velocity uniformity index were used to evaluate the flow field in the mold. The theoretical basis for the optimization of the flow field structure was provided. The study also suggested an optimization method for electromagnetic stirring parameters.
文摘A physical model with mercury as analog was developed to investigate the influences of electromagnetic stirring（EMS） on flow field in slab continuous casting when the submerged entry nozzle（SEN） was clogged with different clogging rates（0,10% ,25% ,and 50% ）. The flow field in mold under different EMS currents（0, 40 A, and 60 A） was measured by an ultrasonic Doppler velocimeter. The results proved that the flow field in the mold was a typical double roll structure under non-clogging SEN. As the SEN clogging rate increased, the flow field structure was transformed from a double roll to asymmetry flow. When the clogging rate reached 50%, the up circulation disappeared on the clogged side. The zone under the meniscus near the narrow face was a non-flowing area. EMS could correct bias flow caused by SEN clogging and improve the symmetry of the flow field during SEN clogging.
文摘To address the phenomenon of sparking during the edge induction heating process in hot strip mills,this paper uses numerical simulation to systematically investigate the key factors influencing sparking and their effects.The distribution of induced current density in the steel plate above roller conveyor table during the heating process is calculated and compared under different conditions,including the relative positions of the steel plate and induction coil,the width of the steel plate,and changes in load. The results show that when a narrow steel plate is heated or the steel plate shifts to the side of the induction coil,sparking between the steel plate and roller conveyor is more likely to occur.
基金financially supported by National Science Foundation of China ( NO. 51274137 and NO. 50874133)
文摘Through physical modeling and numerical simulation,the flow field in a slab continuous casting mold with electromagnetic stirring is measured under different casting parameters and stirring currents. To qualitatively evaluate the flow field in the mold, two indexes,i, e., mold flux entrapment and velocity uniformity, are proposed. Based on these two indexes, some optimized stirring parameters under different casting conditions can be determined.
文摘Based on the modified Scheil model of solute redistribution,the effects of solidification rate,molten steel flow,and alloy composition on solute macrosegregation during the solidification of carbon steel continuous casting billet are calculated and analyzed. The formation mechanism of "white band "segregation under the condition of electromagnetic stirring is also involved,and some practical countermeasures to restrain the central segregation are suggested. The results show that the modified Scheil model can be applied to predict and analyze the macrosegregation of casting slab effectively. The ratio vx/R of the flow velocity of molten steel to solidification rate has decisive formations of segregation such as linear,V,and "white band"types. It is an effective way to select sufficient terminal cooling and reasonable electromagnetic stirring in order to decrease macrosegregation in the slab. The concept of the characteristic distance of solute enrichment layer can drastically simplify the calculation of solute redistribution at the solid/liquid interface of various elements in carbon steel.
文摘Using computer simulation and test measurements,the relationship between the electromagnetic properties of an electromagnetic stirring roller and the roller structure parameters was analyzed and compared. The distribution of the magnetic field,magnitude of the electromagnetic force,and matched-load characteristics were systematically investigated at different parameter values for the induction coils,iron core,shield,and roller sleeve.The results indicate that the change in the electromagnetic force with stirring frequency is non-linear and has a maximum value higher than 10 Hz;the electromagnetic force largely depends on the diameter of the core;and there is a mutual restriction relationship between the two-phase imbalance and the electromagnetic force.
文摘Electromagnetic metallurgy is a technology that achieves molten metal stirring or transportation without contact by electromagnetic force or eddy current, as well as metal heat treatment by induction and diabatic heating, thus to control all kinds of transitions in the metallurgical process efficiently, optimize the internal material structure and improve product quality.
