| 摘要 |
A method for the continuous production of cast steel strands which are 200 mmx200 mm or less in cross-section by a continuous casting process in which molten steel containing over 0.20% of carbon is fed into a casting mold with a lubricant through a submerged nozzle or in an open stream and continuously drawn out downwardly of the casting mold, which includes the steps of (a) electromagetically stirring the molten steel at a position within said casting mold by the application of a magnetic field induced by introducing into an electromagnetic coil an alternating current of a frequency (f) in the range of 1.5 to 15 and maintaining the magnetic flux density (gauss) in the range of 602 e-0.10f to 1844 e-0.12f at the center of the electromagnetic coil, and (b) electromagnetically stirring the molten steel at a position in the final solidifying zone, of the continuously cast strand, in which the shorter diameter of the molten steel pool is smaller than 1/2 the length of the shorter side of the cast strand, by the application of a magnetic field induced by introduing an alternating current into an electromagnetic coil and maintaining the magnetic flux density (gauss) in the range of 0.143xD2+231 to 0.343xD2+451 at the center of the electromagnetic coil, wherein D is the solidified shell thickness in millimeters of the continuously cast strand, the value of the D ranging from 20 to 90, thereby permitting the production of medium and high carbon killed steel billets, which are improved as to segregations, inclusions, surface quality, cold forgeability, and machinability, by a continuous casting process at low cost.
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