行波磁场减速模式对板坯连铸结晶器内传输行为的影响

Effect of Deceleration Mode of Traveling Wave Magnetic Field on the Liquid Steel Transportation Behavior in the Mold of Slab Casting

高拉速高质量连铸生产是当前钢铁冶金领域中绿色低碳发展的重要路径。基于汽车板生产用1000 mm×230 mm断面连铸板坯结晶器内的钢水传输行为研究,探究一种行波磁场减速模式(EMLS)对水口侧孔射流及其钢坯质量的影响。根据电磁热流体与凝固传输理论建立了三维耦合数值模型,利用电导率等效法测试装置测量电磁力校验了模型的准确性,并提出了电磁控流作用下的结晶器综合冶金性能评价依据。结果表明,EMLS电磁力在结晶器宽面两侧呈大小相等、方向相反分布,最佳工作频率为4 Hz,其电流强度对电磁力的影响起主导作用。指出,当前浇铸条件下EMLS的最佳减速电流为200 A。此时,电磁力方向具有指向水口两侧出钢口且略微向下的特征,可以较好地控制其侧孔射流对初凝坯壳的冲刷强度,同时也避免了电磁力作用下弯月面波动过大和钢液冲击深度加深的问题。综合表明,合理利用行波磁场减速控流有望较好地解决当前常见的结晶器液面卷渣和凝固钩对夹杂物与气泡的捕捉,从而有利于提高后续IF钢冷轧板的表面质量。

High speed continuous casting with premium quality is currently a key issue in steel metallurgy for its green low carbon development.The transmission behavior of liquid steel in 1000 mm×230 mm slab continuous casting mold is studied to explore a way for the product quality improvement through nozzle jet flow control by a kind of travelling wave magnetic field deceleration mode.Based on the theory of electromagnetic hot fluid and solidification transport,a coupled three-dimensional numerical model is developed.The model is validated experimentally by electromagnetic force measurement under an equivalent electrical conductivity.The comprehensive effect of the Electromagnetic Level Stabilizer(EMLS)on the metallurgical behavior of mold is proposed based on a multi-parameters evaluation.It is found out that the distribution of electromagnetic force presents a centrally symmetrical pattern on the wide faces of the mold.The optimal frequency of deceleration mode is 4 Hz,and the current intensity plays a leading role to the effect of electromagnetic force.It is suggested that the optimal stirring current intensity should be 200 A for the EMLS to obtain the electromagnetic forces with characteristic of pointing at the nozzle jets downward slightly,which is beneficial to the flow impingement control upon the solidifying shell with less meniscus surface fluctuation and the jet impact depth.It is shown accordingly,that the frequent phenomena such as mold flux involvement and inclusions or gas bubbles under solidification hook could be effectively eliminated by the adoption of mold EMLS,which is vital to the improvement of the final surface quality of IF steel products.