JP2750929B2 - Continuous casting method with spray deposit method - Google Patents

Description

The present invention relates to a continuous casting method to which a spray deposit method is added.

[Conventional technology and its problems]

Generally, the spray deposit method atomizes a molten metal stream with an inert gas, rapidly solidifies finely crushed droplets during scattering, deposits them on a collector, and forms a preform (semi-finished metal) of a desired shape. (See, for example, Japanese Patent Publication No. 54-29985, Japanese Patent Publication No. 56-12220 and Japanese Patent Application No. 62-1849). The microstructure can be formed, there is no macro segregation, and the workability and castability are good.The disadvantages are that the preform is limited to a simple shape, porosity is easily generated, and For example, the yield is poor.

On the other hand, as is well known, the continuous casting method is a general metal rolling production process of melting → ingot → soaking → bulking → heating → rolling, and omitting the steps of ingot, soaking and soaking, It takes a process that can be immediately rolled from molten metal, and its features are not only the reduction of equipment costs due to the simplification of the process, but also the improvement of product yield, as well as the excellent surface and internal quality. ing. However, without precise control, for example, center segregation, porosity, internal cracks, and the like as internal defects are likely to occur, and the metallurgical or mechanical operation is devoted to the operation. In particular, the center segregation is not a metallurgical factor but a very difficult problem because it is caused by mechanical factors peculiar to continuous casting equipment such as roll alignment, roll pitch, and reduction amount.

Therefore, the present inventor has created the following invention for the purpose of compensating for the disadvantages while taking advantage of the respective advantages by combining the two processes of the spray deposit method and the continuous casting method.

[Means for solving the problem]

That is, the gist of the present invention is that the upper surface of the mold (6) on the upstream side of the process for producing a slab by the continuous casting method is covered with the chamber (9), and the central portion of the slab in the chamber (9). In addition, by adding a process of rapid solidification by a spray deposit method, a columnar preform is precast in the center of the slab to prevent porosity generated on the outer periphery of the preform.・ Continuous casting method with a deposit method.

〔Example〕

The present invention will be described in detail based on an example of an apparatus for carrying out the present invention shown in FIG.

The apparatus of this embodiment is a continuous casting facility for casting a billet or bloom. A molten steel 2 for a normal continuous casting method is poured into a first tundish 1 from a ladle (not shown). . Into the second tundish 3, molten steel 4 (having the same composition as the molten steel 2) for performing normal spray deposit is poured from an open induction melting furnace (not shown). An inclined nozzle 5 is provided in the first tundish 1 to introduce the molten steel 2 and to prevent secondary oxidation, and the tip of the nozzle 5 is immersed in a mold 6.

On the other hand, the second tundish 3 is disposed immediately above the mold 6, and a slightly short nozzle 7 is also extended to the tundish 3. The tip of the nozzle 7 is surrounded by an inert gas 8a such as argon ejected from a disk atomizer 8.

These nozzles 5 and 7 and disk atomizer 8
Is filled with an inert gas and covered with a spray chamber 9 for preventing secondary oxidation, and an exhaust gas passage (not shown) communicates with the spray chamber 9.

In addition, 10 is a preform, 11 is a cast shell, and 12 is a pinch roll.

Next, according to an embodiment of the present invention based on the above-described apparatus, a collector (smaller than a dummy bar head) is formed on a dummy bar head of a dummy bar (not shown) used in a normal continuous casting facility. The dummy bar is slightly protruded from above the mold 6 before the operation. Therefore,
First, the molten steel 4 flows down from the nozzle 7 of the second tundish 3, and the inert gas 8 a from the disk atomizer 8 is sprayed on the molten steel 4 to atomize the droplets. The atomized metal particles are deposited on the collector to form the preform 10. At this time, since the preform 10 is formed while the dummy bar is sequentially lowered, the columnar preform 10 can be formed. Next, when the dummy bar comes to the dummy bar set position in the mold 6 in the ordinary continuous casting method, the molten steel 2 flows down from the nozzle 5 of the first tundish 1 and is poured into the mold 6. After the molten steel 2 is filled so as to wrap the outer periphery of the columnar preform 10 already formed, pulling out of the dummy bar is started in the same manner as in a normal continuous casting method, and a slab shell 11 is sequentially formed.

Therefore, the outer periphery of the preform 10 located at the center of the slab shell 11 is remelted by the molten steel 2 by continuous casting, and defects such as porosity that frequently occur on the outer periphery of the preform 10 can be removed. The preform 10 formed by spray deposit has been substantially solidified by rapid cooling.
Coagulation is promoted. Therefore, the production speed of the slab shell 11 can be increased. Further, since the powder generated by the spray deposit is re-melted by the molten steel 2, the yield is remarkably improved. According to the test, 90% or more was obtained.

〔The invention's effect〕

 According to the present invention, the following effects can be obtained.

Since the preform by the spray deposit method is previously cast in the center of the slab, it is possible to prevent defects at the center, which tend to occur in the slab.

The outer periphery of the preform is redissolved by the molten metal by the continuous casting method, and defects such as porosity generated on the outer periphery of the preform can be prevented, and together with this,
It is covered with the chamber and eliminates the boundary layer between the preform and the slab, thereby improving the quality of the produced slab.

Due to the presence of the preform, solidification of the molten metal for the continuous casting method in the mold is promoted, and the production speed of the slab can be increased.

The powder generated by the spray deposit method is re-dissolved by the molten metal used in the continuous casting method.
The yield is further improved.

[Brief description of the drawings]

 FIG. 1 is an example of an apparatus for implementing the present invention. 1,3… Tundish, 2,4… Molten steel, 5,7… Nozzle.

Claims (1)

(57) [Claims] An upper surface of a mold (6) on an upstream side of a process for producing a slab by a continuous casting method is covered with a chamber (9). In the chamber (9), a spray is provided at a central portion of the slab. A spray characterized by adding a process of rapid solidification by a deposit method to cast a columnar preform in the center of the slab in advance to prevent porosity generated on the outer periphery of the preform.
A continuous casting method with a deposit method added.