电磁搅拌对特大方坯结晶器内流场及温度场影响

以某厂断面为410 mm × 530 mm的特大方坯结晶器为原型，利用ANSYS有限元软件建立三维数值模型，研究电磁搅拌对结晶器流场及温度场的影响。施加电磁搅拌后，钢液受到径向电磁力，液面呈现旋转流动趋势。结晶器内钢液最大切向速度随着电流的增加而增大，随着频率的增加而减小。电磁搅拌的电流大小由0 增加到500 A时，液面波动由1.21 mm增加到4.35 mm。电磁搅拌能够使钢水的高温区局限于连铸结晶器上部，钢水温度更加均匀。同时钢液的水平旋流能够抑制初生坯壳的生长，降低坯壳的生长速度，使结晶器出口处坯壳厚度变薄。综合分析，该厂在实际生产时合理的电磁搅拌的电流大小应为400 A，频率为1.5 Hz，此时钢渣液面波动约为2.73 mm，温度场较为均匀。 

Effect of electromagnetic stirring in extra-large billet on the flow field and temperature field

As the “heart” of continuous caster, the flow field of mold directly affects the quality of the slab. For a billet caster, in-mold electromagnetic stirring (M-EMS), as its necessary configuration, can improve the flow field in the mold, homogenize the liquid steel temperature, improve segregation, and improve the slab quality. This paper utilized a 410 mm × 530 mm large billet caster in a factory, which is one of the largest section casters in China. Based on it, a three-dimensional numerical model was established using the ANSYS finite element software to study the influence of electromagnetic stirring on the flow field, liquid level fluctuation, and temperature field of the mold. After electromagnetic stirring was applied, the liquid steel was subjected to a radial electromagnetic force, and the liquid surface shows a rotating flow trend. The maximum tangential velocity of molten steel increases with the increase of current and decreases with the increase of frequency. When the current of electromagnetic stirring increases from 0 A to 500 A, the fluctuation of the liquid level increases from 1.21 mm to 4.35 mm. The maximum tangential velocity of the electromagnetic stirring center increases from 0.02 m?s?1 to 0.21 m?s?1. Electromagnetic stirring can restrain the impact of the high-temperature jet from the nozzle, move the high-temperature zone of molten steel upward, and make the temperature of molten steel more uniform. Under the action of a radial electromagnetic force, the horizontal swirl of liquid steel can inhibit the growth of the primary shell, reduce the growth rate of the shell, and reduce the thickness of the shell out of the mold by about 2.3 mm. The comprehensive analysis shows that the reasonable current of electromagnetic stirring is 400 A and the frequency is 1.5 Hz. At this time, the fluctuation of the slag level is about 2.73 mm, and the temperature field is relatively uniform.