Mechanism and Configuration Selection of Alternating Final Helical Electromagnetic Stirring in Large‐Size Round Bloom Continuous Casting

A coupled multiphysics model involving electromagnetic, fluid flow, solidification, and heat transfer is developed to investigate the alternating final helical electromagnetic stirring (F‐HEMS). The postprocessing is used to apply the Q ‐criterion to extract the rotating fluid's mesh and evaluate the alternating configuration of F‐HEMS. The results show that the alternating stirring mechanism is the rotating fluid's fragmentation and reorganization. Alternating stirring requires pause stirring, as incorporating pause stirring leads to greater stirring depth. Moreover, when stirring is paused, the rotating fluid dissipates within 18 s. Regardless of the specific pause duration, the volume of the rotating fluid consistently reaches a stable value at 55 s, which suggests that multiple cycles are necessary for effective alternating stirring. In addition, the optimal pause duration is determined to be 5 s. After the pause stirring, the stirring direction should be opposite to the original direction; opposite stirring results in a larger stirring volume, width, and depth. In the plant trials, the alternating F‐HEMS configuration derived from the numerical simulations is applied, leading to favorable results in the macrostructure of the strand. Although the alternating F‐HEMS is still an emerging technology, determining the alternating configuration and mechanism significantly contributes to its practical application.