JPH06134556A - Tundish for continuous casting using static magnetic field - Google Patents

Abstract

PURPOSE:To improve the quality of a cast slab by using uniform static magnetic field in the vertical and perpendicular direction to the average flowing speed direction of molten metal pool acted between the outlet and the inlet sides of the molten metal and constituting a tundish wall in the static magnetic field acting range with a conductive body. CONSTITUTION:The uniform static magnetic field 6 in the vertical and perpendicular direction to the average flowing speed direction 5 of the molten metal pool is acted between a long nozzle 1 at the inlet side of the molten metal and an immersion nozzle 3 at the outlet side of the molten metal. By using the electric conductive wall 15 constituting the tundish wall contained in the static magnetic field acting range 12, desirably of the range of the static magnetic field acting range width 13 or more with the conductive body, the efficient braking effect is obtd. By this method, the molten steel stream in the tundish can be braked and the float-up of inclusion and bubbles is promoted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tundish for continuous casting using a static magnetic field.

[0002]

2. Description of the Related Art In a continuous casting tundish, a molten metal jet 2 discharged from a long nozzle 1 generally produces a large molten metal flow 4 between a long nozzle 1 and an immersion nozzle 3 as shown in FIG.

A tundish using a weir 7 as shown in FIG. 7 is disclosed in order to improve the quality of a continuously cast slab by promoting the floating of inclusions and bubbles in the continuous casting tundish. No. 57-170857.

Further, as shown in FIG. 8, continuous casting in which a static magnetic field 6 is applied between a long nozzle 1 of a tundish and an immersion nozzle 3 in a direction vertical and horizontal to a traveling direction 5 of molten metal. Japanese tundish is Sho 6
It is disclosed in Japanese Unexamined Patent Publication No. 3-140745.

[0005]

However, since the wall of the tundish shown in FIG. 8 is an insulator, the induced current 8 forms a loop in the molten metal as shown in FIG. And the induced current 8 is directed horizontally in the vicinity of the surface. Therefore, an upward braking force 10 acts near the bottom on the long nozzle 1 side from the static magnetic field action area center position 9 and near the surface on the immersion nozzle 3 side from the static magnetic field action area center position 9, and the static magnetic field action area center position Position 9
A downward braking force 11 acts near the bottom on the immersion nozzle 3 side and near the surface on the long nozzle 1 side of the static magnetic field working region 9. Since the upward braking force 10 and the downward braking force 11 are perpendicular to the average flow velocity direction 5 of the molten metal pool, the molten metal flow cannot be braked, and the floating effect of inclusions and bubbles is small.

As described above, the present invention eliminates the phenomenon that the induced current forms a loop in the molten metal and is directed horizontally in the vicinity of the bottom and the surface, and efficiently damps the molten metal flow in the tundish to intervene. The purpose is to improve the quality of continuously cast slabs by promoting the floating of objects and bubbles.

[0007]

DISCLOSURE OF THE INVENTION The gist of the present invention is that a uniform static magnetic field perpendicular to the mean flow direction of a molten metal pool in a tundish having a free surface above is applied to the molten metal. In a tundish for continuous casting using a static magnetic field that acts between a long nozzle on the inlet side and an immersion nozzle on the molten metal outlet side, at least a tundish wall included in the static magnetic field acting region is constituted by an electric conductor wall. This is a tundish for continuous casting using a static magnetic field.

[0008]

According to the present invention, as shown in FIG. 1, the static magnetic field 6 is uniform in the direction perpendicular to the mean flow velocity direction 5 of the molten metal pool in the tundish having the free surface above and in the vertical direction.
In the tundish for continuous casting using a static magnetic field, which acts between the long nozzle 1 on the molten metal inlet side and the immersion nozzle 3 on the molten metal outlet side, at least in the static magnetic field acting region 12 Specifically, the tundish wall having a width of the static magnetic field acting region of 13 or more is used as the conductive wall 15 constituted by an electric conductor so that a highly efficient braking effect can be obtained. In addition, the conductive wall 15
It is sufficient that the width is less than or equal to 14 which is twice the width of the static magnetic field acting area, and the thickness thereof is 30 mm or more. Also,
As a conductor, it is recommended to have an electric conductivity of 1 × 10 ⁶ (Ω- ¹ m- ¹ ) or more.

As shown in FIG. 2, in the static magnetic field acting region 12 excluding the vicinity of the side wall, the average flow velocity direction 5 of the molten metal pool is 5.
Since a uniform static magnetic field 6 is applied in a direction perpendicular to and perpendicular to, the braking force 16 in the direction opposite to the traveling direction 5 of the molten metal acts to brake the molten metal flow.

As shown in FIG. 3, the induced current 8 flows out into the conductive wall 15 on the tundish side wall in the static magnetic field acting region 12, and then flows into the conductive wall 15 on the other side wall, whereby the molten metal and the conductive metal are conducted. A current loop is formed with the wall 15.

As shown in FIG. 4, in the static magnetic field acting region 12, the braking force does not act upward and downward unlike the prior art near the bottom and surface of the tundish.
Since a uniform static magnetic field 6 is applied in a direction perpendicular to the traveling direction 5 of the molten metal and in a vertical direction, an induced current 8 is generated in a direction horizontal and vertical to the average flow direction 5 of the molten metal pool. To do. Therefore, the molten metal flow is braked by the braking force 16 acting in the direction opposite to the average flow velocity direction 5 of the molten metal pool.

In addition, an induced current flows out into the conductive wall 15 near the tundish side wall in the static magnetic field acting region 12. Therefore, the induced current 8 is directed horizontally in the vicinity of the side wall of the static magnetic field acting region 12, and the braking force 16 in the direction opposite to that of the molten metal acts, so that the braking effect near the side wall is large. As a result, it is possible to promote the floating of inclusions and bubbles and improve the quality of the continuously cast slab.

[0013]

[Example] In a tundish with a capacity of 50 tons, when the static magnetic field is not applied, the static magnetic field is 5000 gauss and the static magnetic field is applied in the horizontal direction when an insulator is used on all walls. In the case of the method of the present invention using a conductive wall in a wide range including a magnetic field acting area, the distribution amount of inclusions remaining in each slab with respect to the inclusion diameter is metallurgized. Researched. The result is shown in FIG. According to the present invention, it was confirmed that the floating separation of inclusions in the tundish was promoted.

[0014]

The tundish for continuous casting using the static magnetic field of the present invention can stop the molten steel flow in the tundish, promote the floating of inclusions and bubbles, and significantly improve the quality of the cast mold. We were able to.

[Brief description of drawings]

FIG. 1 is a schematic view of the direction of a molten steel flow, a static magnetic field, and a conductive wall in the present invention, (a) is a plan view, and (b) is an elevation view.

FIG. 2 is a perspective view of the direction of the molten steel flow, the static magnetic field, and the direction of the braking force in the present invention as seen from the tundish side wall direction.

FIG. 3 is a perspective view showing an induced current loop according to the present invention, and is an elevation view seen from a longitudinal direction.

FIG. 4 is a perspective view showing the direction of the induced current and the braking force in the vicinity of the bottom according to the present invention, FIG.
(B) is an enlarged elevational view near the surface and (c) is an enlarged elevational view near the side wall.

FIG. 5 is a graph comparing distribution amounts of inclusions trapped in a mold with respect to inclusion diameters in a normal example, a conventional example, and an example of the present invention in the absence of a magnetic field.

FIG. 6 is a perspective view of a flow pattern of molten steel in a tundish when a static magnetic field is not applied, as seen from a tundish side wall direction.

FIG. 7 is a perspective view seen from the side of a tundish for continuous casting using a conventional weir.

8A and 8B are schematic diagrams showing the direction of molten steel flow and the electromagnetic force acting in the conventional method, in which FIG. 8A is a plan view and FIG. 8B is an elevation view.

9A and 9B are perspective views showing a flow pattern of an induced current in a tundish when a static magnetic field of a conventional method is applied, where FIG. 9A is an elevation view and FIG. It is an enlarged view, (c) is an enlarged view of the bottom vicinity of (a).

[Explanation of symbols]

 1 Long Nozzle 2 Molten Steel Jet Jet from Long Nozzle 3 Immersion Nozzle 4 Large Molten Steel Flow 5 Direction of Molten Steel 6 Static Magnetic Field 7 Weir 8 Induced Current 9 Center Position in Width of Static Magnetic Field Action 10 Upward Braking Force 11 Downward Braking Force 12 Static magnetic field acting region 13 Static magnetic field acting region width 14 Double width of static magnetic field acting region width 15 Conductive wall 16 Braking force opposite to the traveling direction of molten steel.

Claims (1)

[Claims] 1. A uniform static magnetic field, which is perpendicular to the average flow direction of the molten metal pool in a tundish having a free surface above and is oriented vertically, is applied to the molten metal inlet side and the molten metal outlet side. In a continuous casting tundish using a static magnetic field to act in between, for continuous casting using a static magnetic field, characterized in that at least the tundish wall included in the static magnetic field working region is a conductive wall constituted by an electric conductor Tundish.