EMBr对高拉速薄板坯钢水动态行为影响的模拟

Simulation of the effect of EMBr on the dynamic behavior of molten steel in thin slab with high casting speed

在高拉速薄板坯的生产工艺研究中,结晶器内钢水流场是决定坯壳均匀性、液面卷渣概率等铸坯质量问题的关键因素。EMBr能够显著改变钢水流场,是改善这些问题的关键工艺技术。因此,对结晶器内钢水流场的模拟、分析与优化是必不可少的工作。以往的研究中,相关的数据与理论指导较少,针对薄板坯无头轧制产线,高拉速连铸机的分析与研究更鲜有报道。因此基于该高拉速连铸机,采用数值模拟方法获得了结晶器内不同电磁制动电流强度的磁感强度分布。采用电磁与多相流耦合模式,针对不同磁感强度条件下的结晶器钢水流场分布与液面形貌进行了仿真模拟,并分析了电磁制动对液面波动的影响。结果表明,基于固定的工况环境,电磁制动电流值为175 A时钢水流场分布均匀,钢水液面流速相对最低,最高流速约为0.6 m/s,同时液面高度差与剪切角相对最小。该条件最有利于减少因坯壳不均或液面卷渣造成铸坯缺陷的概率。电流值225 A相比125 A时,钢水液面位置磁感强度仅提高0.02 T,液面到达稳定时间仅缩短约1 s。因此存在综合评判下的最优电流值。

In the research on the production technology of thin slab with high casting speed,the steel flow field in the mold is the key factor to determine the slab quality problems such as the uniformity of slab shell and the probability of liquid level slag entrapment.EMBr can significantly change the flow field of molten steel,which is the key process technology to improve these problems.Therefore,it is essential to simulate,analyze and optimize the steel flow field in the mold.In the previous research,there are few relevant data and theoretical guidance,and there are few reports on the analysis and research of high casting speed continuous caster for thin slab endless rolling line.Based on the high casting speed continuous caster,the magnetic induction distribution of different electromagnetic braking current intensity in the mold is obtained by numerical simulation.Using the coupling mode of electromagnetic and multiphase flow,the flow field distribution and liquid surface morphology of steel in mold under different magnetic induction intensity are simulated,and the influence of electromagnetic braking on liquid surface fluctuation is analyzed.The results show that:Based on the fixed working condition environment,when the electromagnetic braking current value is 175 A,the flow field of steel is evenly distributed,the liquid surface velocity of steel is relatively lowest,the maximum velocity is about 0.6 m/s,and the liquid surface height difference and shear angle are relatively minimum.This condition is most conducive to reducing the probability of slab defects caused by uneven shell or liquid level slag.When the current value is 225 A,compared with 125 A,the magnetic induction intensity at the liquid level of steel is only increased by 0.02 T,and the time for the liquid level to reach stability is only shortened by about 1 s.Therefore,there is an optimal current value under comprehensive evaluation.