JPS608133B2 - Continuous steel casting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous casting method for steel, and more particularly to a method for treating molten steel during the process from a ladle to a mold in a continuous steel casting method.

・In continuous casting and in general casting, N is present in molten steel.
It is well known that the presence of 203,Ca○-AI203-based inclusions causes defects in the resulting cast products and various products manufactured therefrom. Methods to remove or prevent the occurrence of these inclusions in molten steel include the non-oxidation method, which seals the molten steel with argon between the ladle and the mold to prevent oxidation, and the method of installing a weir in the tundish. There are methods to float and separate inclusions by adjusting the flow and residence time of molten steel in the tundish, and methods to float and separate inclusions in the tundish or mold by blowing argon gas into the molten steel in the tundish or immersion nozzle. Methods such as separation are used. In continuous casting, generally a plurality of ladles are used, and molten steel is continuously poured into the mold through a tundish by exchanging the ladles, so-called multi-lotus coins.

Even if all of the above-mentioned methods for removing inclusions from molten steel or preventing their occurrence are used, in the case of multiple rusting in continuous casting, a considerable amount of inclusions can be found in the product made from the molten steel in the rear pot. By injecting the molten steel from the rear pot into the mold from the tundish's immersion nozzle, the amount of deposits on the immersion nozzle increases significantly, and when it is severe, it causes nozzle damage. Therefore, the current situation is that the use of multi-strand coins made of high-strength steel for pipes must be limited only by taking measures against inclusions as described above.
The object of the present invention is to provide a continuous casting method for steel in which molten steel is continuously injected into a mold from a steel plate through a tundish. Ca found in products cast with molten steel from the rear pot after the second charge at Zenzeizo.
- To provide a method for continuous copper casting in which the inclusions of the mountain 203 series and the mountain 203 series are removed, the erosion of the bond nozzle due to the inclusions is prevented, and the melting loss due to the tundish molten metal is reduced. .

The continuous casting method of steel according to this invention includes a tundish,
A refractory weir with a through hole at the bottom is used to divide the molten steel into multiple damage areas that receive the molten steel from the ladle, and the outlet area that pours out the molten steel from the mold. This method is characterized by changing the receiving area and pouring the molten steel into the mold while maintaining the height of the molten steel surface in the dish above the through hole.

The increase in mountain 203 series and Ca○-AI203 series inclusions in the mirror steel due to the molten steel in the rear ladle in multi-rensen is due to the slag from the front ladle flowing into the tundish. This is thought to be due to mixing and suspension in the water.

The outflow of tundish slag from the ladle occurs at a fairly early stage, and it is difficult to prevent this slag outflow. The method of the present invention will be explained in detail below based on examples.

1 and 2 are schematic cross-sectional views of one embodiment of a tundish used in the method of the present invention. This embodiment shows a twin-type casting machine in which molten steel is injected from one tundish into two continuous casting machines. In FIG. 1, the dish and Kawama ladle 3 used in the method of this invention are molded.

In this embodiment, molten steel is poured into two molds 3, 3a. The weir 11 having a through hole 12 at the bottom of the tandy shoe 0G is also partitioned with a trowel, and the air seal pipe 2 is connected from the ladle 1.
Multiple damaged castle turtles 3a, 13b that receive molten steel through
, 13c, and the immersion nozzle turtle 5 to mold the molten steel into the mold 3.
It is divided into Deyu Castle 14914a, which is located in 3A.

When molten steel is injected from the ladle into the hot water receiving area 13a of the evening dish 10, the molten steel passes through the through hole 12 of the weir 11 into the hot water outlet area 4, and also through the through hole 12 of the weir 11 and the damaged areas 13b, 13.
c to reach the injury area 14a, and each moat thin nozzle 1
5, 15a and is injected into the molds 3, 3a. The height of the molten steel surface 16 is maintained above the through hole 12. Ladle 1
When the pouring of the molten steel of the first charge into the ladle 10 is completed and the ladle is to be replaced, the molten steel of the ladle la of the second charge is poured into a different damage castle 13b as shown in FIG.

The molten steel in the tundish 10 passes through the through hole 12 and other receiving areas 3a and 13c, reaches the molten steel 14 and 14a, and is injected into the molds 3 and 3a. is confined within the hot spring castle 13a by the weir 11,
It floats on the molten steel, and is prevented from being drawn into the molten steel by the injection flow from the rear ladle la. Furthermore, since the molten steel surface 16 is maintained above the through hole 12, it will not flow out to other areas. Ukeyu Castle 13a, 13b? The order in which the stoves 3c are used may be arbitrary. The number of wounded castles is chosen according to the number of times the ladle is charged. Since the method of the present invention is configured as described above, it is possible to significantly reduce AI203 and Ca○-Yama203-based inclusions in the obtained product, especially the product obtained by using Minato steel in the after-pan, and reduce product defects. At the same time, it is possible to reduce the adhesion of inclusions to the tundish nozzle and prevent problems with nozzle clogging, and since the injection port is changed for each ladle, it is possible to reduce melting loss per tundish hot water. .

Next, as concrete performance data, “UOE by continuous casting”
The ultrasonic failure index of the final product of aluminum killed steel for pipes is shown in the table below.

As is clear from the table, when using the conventional method, the number of defects caused by the second charge was nearly three times that of the first charge, but by adopting the method of this invention, this difference almost disappears. ing.

In addition, the amount of inclusions attached to the immersion nozzle is approximately 1
/2.

[Brief explanation of the drawing]

1 and 2 are schematic cross-sectional views of one embodiment of a tundish used in the method of the present invention. In the drawing, 1 is a ladle, 3, 3a is a mold, 10G
matandish, 11 is a weir, 12 is a through hole, 13a, 1
3b, 13c are the castle of injury, 14, 14a are the castle of injury, turtle 5,
15a is a bonding nozzle, 16 is a molten steel surface, and 17 is a slag. Figure 1 Figure 2

Claims (1)

[Claims] 1. In a continuous steel casting method in which molten steel is continuously poured from a ladle into a mold via a tundish; The tundish is divided into a tundish area and a tap area for pouring molten steel into the mold, and each time the ladle is replaced, the receiving area that receives molten steel from the ladle is changed, and the height of the molten steel surface in the tundish is maintained above the through hole. A continuous steel casting method characterized by pouring molten steel into a mold while