直浇道电磁搅拌对连铸坯凝固组织影响

中缩和偏析缺陷对铸坯质量有很大的影响，在直浇道外施加电磁搅拌可以明显地改善连铸坯的凝固组织，并提高连铸坯的质量。选用低熔点Sn-3.55Pb合金浇注试样，用实验方法研究直浇道电磁搅拌对铸坯凝固 组织的影响，并用数值模拟作为辅助手段分析了影响因素。实验证明：施加直浇道电磁搅拌后，铸坯的晶粒细化，等轴晶区扩大，柱状晶区减小；在降低过热度的情况下，施加电磁 搅拌，可避免直浇道堵塞，保证浇注顺利进行，而且铸坯的凝固组织更加细小；在直浇道外施加电磁搅拌，不仅改变了金属液的流动形态，而且提高了浇道内的最低温度，使浇道内的温度分布均匀。

Effects of nozzle electromagnetic stirring (N-EMS) on solidification structure of continuously cast billets

Centerline shrinkage and segregation in continuously cast billets have a bad effect on the quality of cast product. Nozzle electromagnetic stirring (N EMS) is an effective method to refine the solidification structure of continuously cast billets and improve the quality of the cast product. The effect of N EMS on solidification structure of continuously cast metal of Sn 3.5%Pb alloy has been investigated by experiments and numerical analyses. The results show that by imposing N EMS crystal grains of continuously cast billets are refined, and that continuous casting can be conducted at lower pouring temperature and the solidification structure of the obtained billets is much finer. The mechanism of improving solidification structure of billets is applied to the change of flow and the temperature distribution of molten metal in the nozzle.