Numerical Simulation Of Electromagnetic Field And Flow Field In280mm×325mm Bloom Continuous Casting Mold With Electromagnetic Stirring

Being an important application of electromagnetic hydrodynamics in metallurgical industry, the electromagnetic stirring can control the process of thermal and solidification in the mold, and thus improve the quality of bloom. So it is of great significance to study the electromagnetic field and fluid field in mold with M-EMS.Based on the structure of bloom continuous casting mold with electromagnetic stirring in a factory, a numerical simulation model to represent the electromagnetic field and fluid field in continuous casting model was established by using ANSYS11.0software with the finite element and finite volume method in this paper, and the distribution laws of magnetic field and flow field were obtained. The impacts of exciting current intensity, frequency and other parameters were analyzed through numerical simulation and industrial experiment. The main conclusions are as follows:(1) The magnetic flux density reaches its maximum value at the middle plane of the stirrer and become smaller towards the two ends of the mold gradually. On the horizontal plane, the magnetic flux density is bigger on border and smaller on center. The electromagnetic force distributes circumferentially at horizontal plane. The tangential electromagnetic force is proportional to the distance to the bloom center and it has maximum value at the center of the stirrer, in addition, there is another peak at the exit of mold.(2) The magnetic flux density and electromagnetic force increase with the exciting current intensity. As the current intensity increases for each additional100A, the magnetic induction intensity increases about117Gs when current frequency is2.4Hz. Magnetic flux density in the mold decreases with the increasing of frequency. Besides electromagnetic force increases first and then decreases, reaches its maximum value at8.0Hz.(3) Without electromagnetic stirring, the molten steel enters mold and penetrates deep down, then returns upward along the side of solidification to form a single loop. The maximal horizontal flow velocity is only0.006m/s at the middle plane of the stirrer. With electromagnetic stirring, the flow style shifts from vertical downward to horizontal rotary. The maximal tangential reaches0.549m/s when current parameter is400A、2.4Hz.(4) With electromagnetic stirring, the flow field in mold could be divided into three parts: the steel forms a rotary movement in which part named mainstream district; at the top of the mainstream area, it is called up circulation flow, that molten steel flow down by the center and upward by the side of solidification; on the contrary, steel at the bottom of the mainstream zone forms another circulation which flow direction is opposite. The intrusion of the steel flow becomes shallow, so more superheat molten steel stay in the top of mold. It is conducive to heat transfer and dissipation of superheat.(5) Between the ranges of low-frequency which M-EMS is working at, stir intensity increases with the increasing of current intensity and frequency. So vortex flow and secondary flow phenomenon enhanced, the shallower the intrusion of the steel flow shares, the higher the hot area position.(6) This paper also studies the influence of M-EMS on bloom quality through the industrial experiment. With stirring intensity increasing, the quality of bloom getting better, center equiaxial crystal area increases and center loose and center craters decreases.