Recent Topics of Research and Development in Continuous Casting

概要

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Three major issues in continuous casting are nonmetallic inclusions, cracking and segregation. By the application of electromagnetic stirring (EMS) in mold the inclusion entrapment by the growing initial solid shell is hindered and the number of inclusions near the surface of slabs is much reduced. By the application of level magnetic field (LMF) the downward liquid flow induced by the exit flow from submerged entry nozzle is much decelerated and the entrapment of large size inclusions inside the slabs is eliminated, which otherwise cause inner defects. Electromagnetic casting (EMC) prevents from the formation of oscillation mark and hook mark, concomitantly eliminates the entrapment of inclusions and bubbles at the hook mark and also prevents from the formation of surface depression and longitudinal surface cracking in hypo-peritectic steels. Resonance-like unsteady bulging with oscillation of molten metal level in mold causes internal cracking and can be prevented by unequally spaced support rolls. Macrosegregation can be reduced by the proper reduction of casting thickness or, in the case of bloom, the minimization of the size of equiaxed solids, which can be realized by the application of EMS.
2006-12-15