Electromagnetic Stirring In The Round Billet Mold Inclusion Movement Behavior Research

Inclusions in steel have an important impact on its performance, the total oxygen content of the steel can be removed to less than10ppm after refining. Due to reoxidation reaction, slag entrapment and other reasons, the total oxygen content of steel picks up in the continuous casting process, resulting in the inclusion content of casting blank increased. Mold electromagnetic stirring technology can significantly improve the slab quality and the cleanliness of the steel, widely used in continuous casting production. Flowfield and inclusion behavior in mold under electromagnetic stirring were studied more by mathematical simulation and industrial experiment, but the physical simulation especially water simulation studies reported less.In this paper, a1:1physical model was established according to similarity principle. The flow field in mold under electromagnetic stirring was simulated by water model and mechanical agitation. The shape of impeller was constantly improved according to the measured result of flowfield and velocity field in the mold. The similarity of flowfield between mechanical stirring in the water mold and electromagnetic stirring in the steel mold can meet the requirements.The flowfield and inclusion trajectory under traditional straight channel nozzle and swirl-type submerged nozzle in the mold were discussed through the study of mathematical modeling and water model experiment. Study shows that the steel swirling flow can be formed in the mold under the swirl-type submerged nozzle, the nozzle can obviously reduce the impact depth of the jet, accelerate inclusion floatation and move the heat center up.The influence of casting speed and stirring intensity on flowfield and inclusion floatation rate was researched by water model experiment. With the casting speed increased, the impact depth of the outlet was deeper and the removal rate of inclusions reduced. Electromagnetic stirring can transform the water flow impact velocity into the tangential velocity, reduce the impact depth and weaken erose to shell, and create favorable conditions for inclusions gathered up and floatation. Inclusion floatation is higher with the stirring intensity greater when using the swirl-type submerged nozzle. The inclusion floatation increased firstly and then decreased with the stirring intensity increased, and it is highest when the stirring speed48rpm (the maximum tangential velocity0.25m/s).The liquid level state of mold under traditional straight channel nozzle and swirl-type submerged nozzle without electromagnetic stirring was analyzed by mathematical simulation. And the influence of casting speed and stirring intensity to powder entrapment was researched by water model experiment. Study shows that the tangential velocity of liquid level is about0.15m/s when using swirl-type nozzle, larger than using straight channel nozzle, the steel/slag interface is active and meniscus temperature can improve11℃. There is a larger vortex at the mold center when using traditional straight channel nozzle after electromagnetic stirring application. The level fluctuation and fluid flow velocity using swirl-type nozzle is smaller than straight channel nozzle, and there is less prone to slag entrapment.