Jongkeun Kim’s research while affiliated with Romanian Institute of Science and Technology and other places

In order to develop the high frequency electromagnetic continuous casting technology for applying to steel, numerical analysis of the magnetic field and casting experiments using various parameters have been conducted. The method of using cold inserts was well established to lead to a reliable numerical model. According to this numerical model, it was predicted that while casting, the magnetic field would be concentrated on the common region occupied by the coil and the melt and further its maximum value would be seen just below the melt level, Casting experiments have been carried out using tin as a simulating material for steel, No oscillation mark was observed on the billets because the solidification started without hook. Under an optimum condition, billet surface roughness was improved to 1/10 of the conventionally cast billets. The surface quality of the billet was heavily dependent on the melt level, the casting speed, and the coil current. In case of the excessive coil current, wave marks other than the oscillation mark appeared on the billet surface. The billet with proper electromagnetic conditions showed a thinner solid shell at the early stage of the solidification and a thicker shell at the mold bottom in comparison with the conventional cast billet. It has been concluded that the Joule heat is a more dominant factor than the magnetic pressure in determining the surface quality of cast products in the high frequency electromagnetic continuous casting process.

The objective of this study is to improve the surface quality of the billet by applying high-frequency magnetic field electromagnetic casting technology to the continuous casting of steel. In this study, the effect of the mold shape on the steel billet surface quality was examined by a continuous casting experiment. It also researched the effects of electromagnetic field on the surface quality of the billet by observing the shape of the early-solidified shell as well as measuring the meniscus shape and mold flux consumption. Through the experiment, it was found that billet surface roughness was improved to 1/5 of the conventionally cast billets under an optimum condition. This study also discovered that a hook formed on the early-solidified shell and molten steel overflowed when an electromagnetic field was not applied. However, in the electromagnetic casting, a hook did not form in the meniscus and the early-solidified shell grew and became thin and even. The corner shape of the mold also had a great effect on the surface quality of billet's corner. In addition, it was found that mold flux consumption is increased during electromagnetic casting.