Numerical simulation of electromagnetic field and flow pattern in a continuous slab caster with in-roll type strand electromagnetic stirring

Electromagnetic Forces in Continuous Casting of Steel Slabs

“…Alternatively, EMC applies vertically-moving magnetic fields near the meniscus [36][37][38]. Other types of moving field systems-SEMS and S-EMS-are applied to the strand below the mold [33,[40][41][42][43][44][45][46][47].…”

“…Finally, SEMS in slab casting creates large vertical recirculation regions below the mold, designed to control superheat, solidification, grain structure, and solute distribution [33,[40][41][42][43][44][45][46][47]. The one-way horizontally-moving fields in SEMS create Lorentz forces which directly drive the molten steel across the strand towards one of the narrow faces.…”

“…After impinging on that narrow face, the flow splits vertically upward and downward. With one magnetic field or an "in-roll" pair of moving field systems on each side of the strand, this results in two large, counter-rotating vertical recirculation regions across the entire strand width, which extend far above and below the SEMS field region [41,42,[45][46][47]. With two sets of two pairs each of in-roll-type SEMS stirrers employed, SEMS can generate three flow recirculation zones across the strand, which induce stronger effects on mixing the flow, compared to single-pair in-roll SEMS [42].…”

“…With one magnetic field or an "in-roll" pair of moving field systems on each side of the strand, this results in two large, counter-rotating vertical recirculation regions across the entire strand width, which extend far above and below the SEMS field region [41,42,[45][46][47]. With two sets of two pairs each of in-roll-type SEMS stirrers employed, SEMS can generate three flow recirculation zones across the strand, which induce stronger effects on mixing the flow, compared to single-pair in-roll SEMS [42]. The top surface flow in the mold is not affected much by SEMS, so the importance of this mixing flow is related mainly to effects on superheat distribution, temperature gradients at the solidification front, grain structure, porosity, and segregation in the strand, which are discussed later.…”

“…This slab-casting SEMS differs from S-EMS in bloom and billet casting, which can have either horizontal rotating magnetic fields around the strand perimeter as with M-EMS [33,40] or longitudinal moving fields that produce recirculating flow in the vertical plane through the strand thickness [41]. The slab-casting SEMS produces vertical recirculating flow regions across the strand width, both above and below the SEMS field region [33,[40][41][42][43][44][45][46][47], which aims to control heat transfer and solidification/nucleation phenomena, to increase equiaxed grains and to reduce segregation and porosity [33,42,43].…”