| 摘要 |
<p>PROBLEM TO BE SOLVED: To cast the slab free from surface defects by specifying the surface tension of the flux for continuously casting steel at 1500 deg.C and the viscosity at 1300 deg.C in the range of the respective prescribed values. SOLUTION: In the flux for continuous casting, the surface tension at 1500 deg.C is in the range of 0.4∼0.6N/m, and the viscosity at 1300 deg.C is in the range of 0.05-0.5Pa's respectively. When the surface tension at 1500 deg.C exceeds 0.6N/m, inclusions and bubbles are left on the interface to generate surface defects. On the other hand, when the surface tension is smaller, the molten flux can be included in the molten steel, and the lower limit to prevent this phenomenon is 0.4N/m. When the viscosity of the molten flux at 1300 deg.C is lower than 0.05Pa's, not only inclusion of the molten flux into the molten steel is generated but also the excessive flow-in is generated to cause the surface cracking. When the viscosity exceeds 0.5Pa's, the heat flux in a mold is increased due to insufficient flow-in of the flux to cause defective lubrication, depression, and surface cracking.</p> |
