JPS5843174B2 - Kinzokunorenzokuchiyuuzouhouhou - Google Patents

Description

[Detailed Description of the Invention] In the continuous casting of metals, especially steel, curved continuous casting machines and vertical bending continuous casting machines with low equipment height are the mainstream. occupies
In recent years, various low-head continuous casting machines have been developed that aim to further reduce the height of equipment.

On the other hand, in order to improve the productivity of continuous casting machines, high-speed casting was aimed at, and so-called unsolidified straightening, in which slabs were straightened before they were completely solidified, was adopted, thereby suppressing internal cracks in slabs that were caused by unsolidified straightening. Development of straightening technology for this purpose is also progressing.

During high-speed casting with these curved continuous casters, vertical bending continuous casters, or other low-head continuous casters, the solidification of the slab is completed in the horizontal section after the straightening point, and the casting speed increases. The larger the horizontal coagulation zone, the larger the horizontal coagulation zone.

In continuous metal casting, little attention has been paid to the effect of the above-mentioned horizontal solidification on the quality of slabs.

This is probably because high-speed casting technology is being studied for relatively low grade steels.

The present inventors have repeatedly conducted high-speed casting tests of high-grade steel using the curved continuous caster shown in Fig. 1, and found that the horizontal solidification zone after the straightening point becomes longer and solidification shrinkage holes appear in the center of the slab. It was confirmed that the formation was remarkable.

Further, the present inventors conducted various tests and studies on measures to prevent defects caused by shrinkage porosity formed by high-speed casting, and were able to accomplish the present invention.

The present invention is designed to suppress the formation of shrinkage holes in the center of slabs caused by horizontal solidification when performing high-speed continuous casting using a curved casting machine, a vertical bending casting machine, etc., as shown in Fig. 2. An electromagnetic induction pump 8 is installed at one or more positions between just before the straightening point and the position where the horizontal part solidification is completed.
This involves a method in which a moving magnetic field is applied in the direction of completion of solidification, causing the molten metal to flow in that direction.

By this method, shrinkage defects in the center of the slab can be almost completely suppressed. Hereinafter, the content of the present invention will be specifically explained with reference to the drawings.

When casting a carbon steel bloom with a cross section of 250 mm x 300 mm from the mold 1 at a high speed of 1.5 m/min using a semi-circular curved continuous casting machine with a radius of 12 m as shown in Fig. 1, the slab 2
The complete solidification position 6 is from the first straightening roll 3 to jlOm
The horizontal coagulation zone is about 10 doors.

In conventional casting methods, the supply of molten steel to the horizontal part is insufficient, and shrinkage holes are often formed in the area where the slab solidifies in the horizontal part. There were problems such as oxidation.

FIG. 2 is a diagram showing an embodiment of the present invention, and FIG. 3 is a partially enlarged view of the same, in which a second straightening roll 4 and a third straightening roll 5 are used as a measure to suppress the formation of shrinkage holes due to horizontal solidification. A linear induction electromagnetic pump 8 is installed between them, and the direction of the final freezing point 6, that is, L
A moving magnetic field is applied in the direction of , the unsolidified molten steel 7 is caused to flow in the L direction, and the molten steel is smoothly supplied to the horizontal solidification section, thereby suppressing the formation of shrinkage holes.

In the example shown in Figure 2, the casting speed is 1.5 m and the horizontal solidification zone length is approximately 1.
In the case of 0 m, installing an electromagnetic pump in one location was sufficient, but if the casting speed is further increased and the horizontal solidification zone becomes longer, electromagnetic pumps should be installed in two or more locations. is valid.

As is clear from the above examples, the center shrinkage porosity defect, which is a problem during high-speed casting, is almost completely solved by the method of the present invention.

The method of the present invention is also an extremely effective means for horizontal continuous casting machines in which the entire slab solidifies in a horizontal or nearly horizontal state.

Furthermore, even if there is no horizontal solidification zone, in a continuous casting machine where the distance between the mold and the complete solidification position is long, it is effective to apply the method of the present invention in front of the complete solidification position.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a continuous casting machine to which the present invention is applied;
FIG. 2 is an explanatory diagram showing an embodiment of the present invention, and FIG.
It is an enlarged sectional view showing details of part A of the figure. 1... Mold, 2... Slab, 3-5...
...First to third straightening rolls, 6... Completely solidified slab position, 7... Unsolidified molten steel, 8...
・Electromagnetic pump, L...Moving magnetic field.

Claims (1)

[Claims] 1. In a metal continuous casting machine with a horizontal solidification zone, an electromagnetic induction pump is installed at one or more positions between just before the horizontal part and the horizontal part solidification end position, and the electromagnetic induction pump is installed at one or more positions between the horizontal part and the solidification end position, and the metal is solidified in the horizontal part. A continuous metal casting method characterized by suppressing the formation of shrinkage holes due to solidification in horizontal portions by causing the molten metal to flow in the direction of completion of solidification.