帘线钢82B小方坯电磁搅拌结晶器多场传输行为

连铸电磁搅拌结晶器内钢液流动、传热、传质和凝固行为十分复杂且对铸坯质量影响巨大,为了进一步揭示电磁搅拌结晶器内多物理场传输行为及其相互影响规律,建立了电磁场作用下三维多物理场耦合连铸凝固模型,模拟研究了结晶器电磁搅拌对帘线钢82B小方坯连铸过程的影响。结果表明,随着搅拌电流强度增大,钢液流动加强;结晶器出口附近铸坯中心纵向流速先减小,进而流速反向,之后反向的流速增大,促进热量散失,加剧了小方坯皮下负偏析,同时促进了钢液池溶质浓度提高。当搅拌电流为280 A时,搅拌器中心铸坯横截面上最大切向速度达到0.23 m/s,距离弯月面1.5 m位置,负偏析低谷碳的质量分数为0.706%,铸坯中心碳的质量分数达到了0.872%。

Multi-physical transport in billet mold of cord steel 82B with electromagnetic stirring

Transport phenomenon of momentum, heat, and solute are very complicated during solidification process of continuously casting billet with mold electromagnetic stirring (MEMS). So, mold electromagnetic stirring has great influence on the billet quality. In order to study the effect of MEMS on complicated transfer phenomenon and understand interactions between them during billet solidification process, a 3D multi-physical fields coupling model for continuous casting process with MEMS was established. Solidification process of cord steel 82B billet in mold with MEMS was simulated with this model. The model was validated by comparison between simulated and measured results. Numerical results show that, as MEMS current increase, flow intensity in mold become stronger, vertical flow velocity at billet center near the exit of mold first decrease, then turn round, and increase continuously. Heat transfer of billet, subcutaneous negative segregation of 82B billet, and solute enrichment in melt pool of 82B billet during continuous casting process are all promoted with increasing mold electromagnetic stirring current. As electromagnetic stirring current is 280 A, maximum tangential velocity of liquid steel along X-axis in cross sections at MEMS center is 0.23 m/s, and minimum mass fraction of carbon at negative zone and mass fraction of carbon in liquid pool at billet center are 0.706% and 0.872% respectively in the cross section 1.5 m away from meniscus