JPH07204804A - Molten Steel Flow Control Method in Mold in Continuous Casting - Google Patents

Abstract

(57) [Summary] [Object] The present invention, in continuous casting of steel, uniformizes a non-uniform swirling flow generated in the vicinity of the inner circumference of the mold as seen in conventional electromagnetic stirring in a mold, and causes bubbles in the molten steel surface layer. The quality of continuous cast slabs is improved by reducing defects caused by trapping of inclusions and inclusions or vertical cracks caused by uneven solidification. [Structure] In a molten steel strand in which a swirling flow has been generated in molten steel by an electromagnetic stirring device in a mold, at the center position in the mold thickness direction, and from one mold short side 1/5 of the mold width to the other mold short position. A plate is inserted within a range from the side to a position of 1/5 of the mold width, and the molten steel flow in the mold is controlled by both the electromagnetic stirring in the mold and the inserted plate.

Description

Detailed Description of the Invention

[0001]

The present invention relates to continuous casting of steel,
The present invention relates to a molten steel flow control method in a continuous casting for the purpose of improving the quality of a continuously cast slab by swirling the molten steel in the mold by electromagnetic stirring.

[0002]

2. Description of the Related Art As a method for controlling the molten steel flow in a continuous casting mold by using electromagnetic stirring in the mold for the purpose of improving the quality of a continuous casting slab, conventionally, as shown in FIG. It is common practice to generate a swirling flow 1 horizontally in the vicinity. Reference numeral 10 represents an immersion nozzle.

[0003]

However, in the above-mentioned conventional method, as shown in FIG. 4, the flow 2 along one mold long side induced in the molten steel by electromagnetic stirring and the other mold long side are induced. The flow becomes unstable in the vicinity of the position 4 where it comes into contact with the flow 3 along the flow, and turbulence is generated there. Therefore, a uniform swirling flow cannot be obtained near the inner circumference 5 of the mold near the molten metal surface. As a result, it becomes difficult to uniformly solidify the molten steel, and the quality of the continuously cast slab cannot be improved.

The present invention homogenizes the non-uniform swirling flow generated in the vicinity of the inner periphery of the mold, which is seen in the conventional method, and causes defects caused by trapping bubbles and inclusions in the molten steel surface layer, or vertical solidification due to non-uniform solidification. The purpose is to reduce cracking and improve the quality of continuously cast slabs.

[0005]

As shown in FIG. 1, the present invention provides a center in the thickness direction of a mold in a molten steel strand in which a swirling flow is generated in the molten steel by an electromagnetic stirring device in the mold during continuous casting of steel. At position 6 and 1/5 of the mold width from one mold short side, from position 7 from the other mold short side 1/1 of the mold width
5 is a method for controlling molten steel flow in a mold, in which a plate 9 is inserted within a range up to position 8 and electromagnetic stirring in the mold and both of the inserted plates are used to control the molten steel flow in the mold.

[0006]

According to the present invention, as shown in FIG. 2, electromagnetic stirring is applied to the inside of the mold to move from the position 7 which is ⅕ of the mold width from one mold short side along the center position 6 in the mold thickness direction. A plate 9 having an appropriate length is inserted within a range from the other short side of the mold to a position 8 which is ⅕ of the mold width, and a flow induced by electromagnetic stirring is applied to the flow 2 along both long sides of the mold. Divide into 3. Since the flows 2 and 3 are clearly divided, instability does not occur at the boundary of the flows 2 and 3 and the flow is not disturbed as in the conventional method, and a uniform swirling flow is obtained in the circumferential direction of the mold. It is possible to make the solidification uniform, reduce the occurrence of vertical cracks in the cast slab, and improve the quality of the obtained continuous cast slab.

The plate to be inserted into the mold is made of a refractory material or the like in terms of material, and it is preferable that the plate is attached so as to extend from the immersion nozzle 10 like a blade as shown in the drawing. The depth should be within the range where swirl flow occurs.

[0008]

EXAMPLES In a curved slab continuous casting machine (radius 10.5 m) having a width of 1380 mm and a thickness of 250 mm, a conventional method in which electromagnetic stirring is applied in the mold and the plate is not inserted into the molten steel strand, Was cast by the method of the present invention in which each of the slabs was inserted, and the occurrence rate of vertical cracks in each slab was investigated. The results are shown in Table 1. According to the present invention, it was confirmed that the number of vertical cracks generated was smaller than in the past.

[0009]

[Table 1]

[0010]

By carrying out the molten steel flow control method in a mold in continuous casting according to the present invention, the molten steel flow in the mold can be controlled, vertical cracks can be prevented, and the quality of the cast slab is significantly improved. I was able to.

[Brief description of drawings]

FIG. 1 is a view showing the installation position of a plate according to the method of the present invention as viewed from above in the vertical direction.

FIG. 2 is a schematic view seen from above in the vertical direction for explaining the flow pattern of the molten steel surface in the method of the present invention.

FIG. 3 is a schematic view of a flow pattern of a molten steel surface in a conventional method as viewed from above in a vertical direction.

FIG. 4 is a schematic view seen from above in the vertical direction for explaining a flow pattern of a molten steel surface and a mechanism of its turbulence in a conventional method.

[Explanation of symbols]

 1 Swirl flow 2 Flow along one mold long side 3 Flow along the other mold long side 4 Position where 2 and 3 contact 5 Inner circumference of mold 6 Center position in mold thickness direction 7 Mold width 1 from one mold short side / 5 position 8 1/5 position of mold width from the other mold short side 9 Plate 10 Immersion nozzle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eiichi Takeuchi 20-1 Shintomi, Futtsu City, Chiba Shin Nippon Steel Co., Ltd. Technology Development Division

Claims (1)

[Claims] 1. In continuous casting of steel, in a molten steel strand in which a swirling flow is generated in molten steel by an electromagnetic stirring device in a mold, at a center position in the thickness direction of the mold and from one of the mold short sides to 1 / m of the mold width. Characterized in that a plate is inserted within a range from the position of 5 to the position of 1/5 of the mold width from the short side of the other mold, and the molten steel flow in the mold is controlled by both the electromagnetic stirring in the mold and the inserted plate. Method for controlling molten steel flow in a mold.