Primary columnar crystal growth characteristics affected by double stirrings in continuous casting square billet

Abstract

The primary columnar crystal deviates due to forced flow induced by a mold electromagnetic stirrer (M-EMS). On this basis, the flow field can be qualitatively analyzed. As the growth characteristics of primary columnar crystal by double stirrings are still unknown, an electromagnetic swirling flow in the nozzle (EMSFN) approach was applied with M-EMS during a plant trial of continuous casting square billet. We first investigated the deflected angle of the primary columnar when using M-EMS or EMSFN solely. The deflected angle reduces gradually from the billet surface to the center when using only M-EMS. With increasing the EMSFN current, the deflected angles increase first, then reduce. When double stirrings with opposite directions are applied, the deflected angles fluctuate between positive and negative values near the billet surface. When the current is 600 A, the ratio of negative angles reaches 45%. This fluctuation of growth direction forms an interlaced dendrite structure, which restrains the solute migrating to the billet center.