Simulation Of Magnetic Field Of Final Electromagnetic Stirring And Application

With the increasing advance of requirements of steel quality by users, electromagnetic stirring technique has been applied worldwide. But several defects are usually found in the continuous casting of steel, such as center segregation, V segregation and central porosity, especially for high carbon steels. Final electromagnetic stirring (FEMS) is a effective method for improving the steel quality and these defects are improved through it in the continuous casting of high carbon steel.Begin with the using of the FEMS in the electric furnace plant of Nanjing steel group, taking the FEMS in the continuous casting of the billets as research object, this subject studies the influence of the electromagnetic parameters to the electromagnetic field. With this purpose, electromagnetic stirring was investigated in aspects of theoretical analysis, mathematic model, computer simulation, local measurement and operation.During the theoretical analysis of electromagnetic stirring processing of continuous casting of square billet, several elementary dimensionless numbers including Reynoldenumber(Re), magnetic Reynolde number( Rem ),Hartman number(Ha) and magneticinteraction number(N) were used to explain the hypothesis in the study of electromagnetic stirring. The analysis and computation in the electromagnetic stirring processing were simplified through these hypothesis. This theoretical analysis also presents the theoretical principle for the analysis of distribution of the electromagnetic field and force.During the computer simulation of electromagnetic stirring processing, because of the limit of the present software to solve the coupled field, simulation program was complied by the author and was taken as simulation tool due to its analysis function of electromagnetic field and force. The calculation modeling of electromagnetic field was established base on finite element analysis theory. Based on the computer language FORTRAN90,three dimension electromagnetic field was made to compute the distribution of the electromagnetic field and force. Further more, the max velocity in the front of solidification was computer by the simple model.For further explore of the characteristic of electromagnetic parameters and magnetic flux distribution and to select EMS parameters, the magnetic flux of rotating magnetic field in square billet were measured in workshop. The influence of EMS parameters (such as electric current strength and frequency) on the velocity of molten steel in the billet was investigated with computer simulation. The simulated magnetic flux and measured one had same distribution rule. That shows the simulation is reasonable. The research results provide the theory basis for parameter selection of the EMS electromagnetic parameters of continuous casting. Based on the results obtained from modeling, computer simulation and industrial trial, the influence of these electromagnetic parameters on strand quality was certified.Finally, the research results of FEMS process in continuous casting were summarized. Meanwhile, the research direction and object were also pointed out. One is about the aspect of theoretical research. With the development of calculation technique in the future, electromagnetic field, flow field temperature field and concentration field should be completed coupled. So the EMS mechanism in continuous casting would be intensively comprehended. The other is about the aspect of application of the FEMS. The selection of the installation position and electromagnetic parameters should be further researched. So best condition parameters and electromagnetic parameters would be explored in order to obtain billets with equiaxed crystal.