Abstract
This research work was conducted to find the possibility of controlling the initial solidification in the continuous casting processes with the triple point by appling high frequency electromagnetic field. Some continuous casting processes such as the horizontal continuous casting have the triple point defined as the intersection of a refractory, a mold and molten steel. Since the triple point has a role of initiating solidification shell, proper initiation of solidification at the point is required. The imposition of high frequency electromagnetic field on the triple point was investigated to achieve the appropriate solidification control.
First of all, numerical calculations were done to estimate the magnetic pressure and the joule heat. Then, bench scale experiments and plant tests with the horizontal continuous caster in Keihin Works were carried out. An induction coil was installed around the triple point and driven at 3kHz in both cases. For the bench scale experiments, 250kg of plain carbon steel was cast into a round billet with 65mm in diameter, and for the plant tests 50t of high carbon steel was cast into billets with 330mm in diameter. The cast surface appearance and subsurface solidification structure were examined. Without electromagnetic field, the triple point defects such as rough surface and irregular subsurface solidification structure appeared on the cast. On the other hand, almost no such defects were observed.
Better bonding between the shell tip and the molten metal near the triple point was supposed to be promoted by the electromagnetic field.
