To produce a cast slab having few inclusion and excellent cleanliness even under high speed casting by sufficiently solidifying slag in a ladle and preventing the slag from flowing out of the ladle into a tundish, and also by further improving the cleanliness of molten steel located adjacent to the slag in the ladle, compared to before.
Molten steel tapping is performed from a converter furnace to a ladle in an undeoxidized state. After the molten steel tapping, a lower oxide in the slag is reduced by adding metal Al or Al dross to the slag in the ladle. Also, a MgCO3-containing material is added to the slag so that MgO concentration in the slag is 6-15 mass%. Then, in a vacuum degassing system, carbon in the molten steel is brought into reaction with dissolved oxygen, thereby reducing the concentration of the dissolved oxygen to 0.050 mass% or less. After the concentration of the dissolved oxygen becomes 0.050 mass% or less, the molten steel is deoxidized with metal Al, without using Mn as a deoxidizing agent. When adjustment of the Mn component in the molten steel is necessary, the Mn adjustment is performed by the addition of Mn-containing metal after the Al-deoxidization, and then the molten steel is cast into a cast slab in a continuous caster.
ARAMAKI NORICHIKA
INOUE NOBORU
NISHIGORI MASANORI
| JP2000087131A | 2000-03-28 | |||
| JP2003171714A | 2003-06-20 | |||
| JPH08325627A | 1996-12-10 | |||
| JPH10317049A | 1998-12-02 |
Kazuhiro Mori