Influence of Electromagnetic Brake on Hook Growth and Inclusion Entrapment Beneath the Surface of Low‐Carbon Continuous Casting Slabs

Abstract

In the current study, the entrapment of inclusions by hooks under electromagnetic brake (EMBr) is investigated through hook reveal and inclusion detection at the subsurface of slabs. Simulation is performed to present the fluid flow and the temperature at the meniscus of the mold. With the application of EMBr in the simulation, the steel jet from the submerged entry nozzle (SEN) deflected upward, the speed of upper backflow increased, and the temperature of steel at the meniscus also increased. The measured average depth of hooks and the number density of >10 μm inclusions without EMBr are larger than those with EMBr. With the application of EMBr, the high temperature of the liquid steel at the meniscus prevented the growth of hooks, and small hooks could only capture few inclusions. Hence, the surface quality of slabs could be improved with EMBr.

Electromagnetic Forces in Continuous Casting of Steel Slabs

“…The change in the bubble transport with double-ruler EMBr tends to decrease the fraction of bubbles captured into the solidifying steel, as shown in Figure 22b, especially the 0.1mm size [82,138]. In addition, less deep hooks, due to more superheat towards the meniscus region with double-ruler EMBr, can reduce inclusion capture into the hooks [132] as shown in Figure 23. meniscus region with double-ruler EMBr, can reduce inclusion capture into the hooks [132] as shown in Figure 23.…”

“…More superheat is delivered towards the surface with stronger upward flows if the lower ruler is stronger and the upper ruler field is far above the nozzle ports [115,132]. This increases meniscus temperatures [115,132]. This can decrease the depths of oscillation marks and subsurface hooks, which are strongly related to low temperature distributions near the meniscus [100,101], as shown in Figure 19 [132].…”

“…This increases meniscus temperatures [115,132]. This can decrease the depths of oscillation marks and subsurface hooks, which are strongly related to low temperature distributions near the meniscus [100,101], as shown in Figure 19 [132]. Alternatively, abnormally high strength or low location of the upper ruler field can make the meniscus flow stagnant, causing associated surface defects.…”

“…Thus, superheat transport towards the stop surface is more adjustable by independent control of the field strengths of two rulers. More superheat is delivered towards the surface with stronger upward flows if the lower ruler is stronger and the upper ruler field is far above the nozzle ports [115,132]. This increases meniscus temperatures [115,132].…”

“…This makes superheat transport and temperature distribution more uniform near the solidifying steel shell, especially where the meniscus tends to be cold, near the SEN Figure 19. (a) Subsurface hooks and (b) the effect of double-ruler EMBr on hook depth in the steel slab [132].…”