JPH07314104A - Method for controlling fluidity of molten metal in mold in continuous casting - Google Patents

Abstract

PURPOSE:To improve the quality of a continuously cast slab by uniformizing the revolving flow in the peripheral direction of molten metal surface in the continuous casting preventing the development of fault. CONSTITUTION:An electromagnetic stirring device 2 is arranged so as to position the molten steel surface 1 within a range 6 from the center 3 of a core to the upper end of the core and the uniform revolving flow is formed in the peripheral direction of a mold 7 near the molten steel surface 1, and the solidification at the initial stage is uniformized, and the entering of gas bubbles and inclusion of the surface layer into the solidified shell is reduced. By this method, the uniform revolving flow is obtd. in the peripheral direction of the mold near the molten steel surface to make the initial solidification uniform, and the longitudinal crack caused by the uneven solidification of the cast slab is prevented, and the quality of the cast slab is improved.

Description

Detailed Description of the Invention

[0001]

The present invention relates to continuous casting of steel,
The molten steel in the mold is swirled by electromagnetic stirring, and a device is installed at a position where the effect of electromagnetic stirring is effective, and by effectively controlling the molten steel flow, defects and solidification caused by trapping bubbles and inclusions in the surface layer 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 reducing vertical cracks caused by nonuniformity.

[0002]

2. Description of the Related Art For the purpose of improving the quality of continuously cast slabs,
As a method of controlling the molten steel flow in the continuous casting mold using electromagnetic stirring in the mold, a method in which an electromagnetic stirring device 2 is installed below the molten steel surface 1 as shown in FIG. 1 to generate a swirling flow is generally used. ing.

[0003]

However, in the conventional method described above, the swirl flow 4 is formed at the core center position 3 as shown in FIG. 2, but is formed at the core center position 3 on the molten steel surface 1. The flow 5 derived from the swirling flow 4 becomes dominant, a uniform swirling flow cannot be obtained in the circumferential direction of the mold near the molten metal surface, uniform solidification is difficult, and vertical cracks occur, and bubbles and inclusions are generated in the surface layer. It also causes trapping, and cannot improve the quality of continuously cast slabs.

The present invention provides a molten steel flow control method in a continuous casting in which the swirling flow in the circumferential direction of the casting mold on the surface of the molten steel is made uniform to improve the quality of the continuously cast slab.

[0005]

According to the present invention, as shown in FIG. 3, in the continuous casting of steel, the position of the molten steel level is set so that the electromagnetic stirrer is installed at a position where the electromagnetic stirrer effect is effective. Core center 3 of electromagnetic stirrer 2 installed around mold 7
It is a molten steel flow control method in continuous casting, characterized in that the molten steel flow in the mold is swirled to control the molten steel flow by installing the apparatus so as to be within a range 6 from the core to the upper end of the core.

[0006]

According to the present invention, as shown in FIGS. 3 and 4, the electromagnetic stirrer 2 is installed so that the molten steel level 1 is located within the range 6 from the core center 3 to the upper end of the core. A uniform swirl flow is formed around the surface 1 in the circumferential direction of the mold 7 to make the initial solidification uniform and reduce trapping of surface layer bubbles and inclusions in the solidified shell.

Here, a uniform swirling flow 4 on the molten steel surface 1
Since it is formed, it becomes possible to reduce vertical cracks due to uneven solidification of the cast slab and significantly improve the quality of the continuously cast slab, as compared with the conventional method.

[0008]

Example In a curved slab continuous casting machine (radius 10.5 m) having a cross section of width 1380 mm and thickness 250 mm,
Incidence of vertical cracks in each slab cast by the conventional method in which the upper end of the core is installed 300 mm or less from the surface of the molten metal by electromagnetic stirring in the mold and the method of the present invention where the center of the core is installed in the meniscus position investigated.

The results of this investigation are shown in Table 1. From this result, it was confirmed that the number of vertical cracks was reduced in the case of the present invention.

[0010]

[Table 1]

[0011]

As described above, according to the molten metal flow control method in a mold of the present invention, this apparatus is installed so as to be within the range from the core center of the electromagnetic stirrer installed around the mold to the upper end of the core. By swirling the molten steel flow in the mold and controlling the molten steel flow, a uniform swirling flow is formed in the circumferential direction of the mold near the molten steel surface, homogenizing the initial solidification and forming a solidified shell of surface bubbles and inclusions. It becomes possible to prevent the vertical cracks resulting from the non-uniform solidification of the cast slab and to significantly improve the quality of the continuous cast slab.

[Brief description of drawings]

FIG. 1 is a schematic side view of a mold showing an installation position of a conventional electromagnetic stirring device.

FIG. 2 is a perspective view schematically showing the flow pattern of the molten steel surface at the installation position of the electromagnetic stirrer in the conventional method.

FIG. 3 is a schematic side view of a mold showing an installation position of an electromagnetic stirrer according to the method of the present invention.

FIG. 4 is a perspective view schematically showing the flow pattern of the molten steel surface at the installation position of the electromagnetic stirrer according to the method of the present invention.

[Explanation of symbols]

 1 molten steel surface 2 electromagnetic stirrer 3 core center position 4 swirl flow 5 flow derived from swirl flow 6 range from core center 3 to core upper end 7 mold

Claims (1)

[Claims] 1. In continuous casting of steel, the apparatus is installed so that the position of the molten steel surface is within the range from the core center of the electromagnetic stirrer installed around the mold to the upper end of the core. A method for controlling molten steel flow in a mold in continuous casting, characterized in that the molten steel flow is controlled by swirling.