JPH09192784A - Production of complex cast slab - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a complex cast slab having clean interface between a base material and a clad material by drawing in the unidirection while solidifying and depositing a steel or a metal for the clad material on one side or both sides of the base material steel plate. SOLUTION: The base material steel plate 3 is passed under condition of dipping the one side surface into molten metal 2 having different composition as the clad material held on the free surface of a molten metal bath B3. At this time, the clad material 4 which solidifies and welds the molten metal 2 for the clad material on the dipping surface, is formed. The cast slab is bent in little upward with a supporting point roll 13 at the inlet side of the third bath B3 and drawn out with pinch rolls 14 at a desired drawing-out elevation angle θ. The thickness of the clad material 4 is controlled by adjusting the drawing-out angle θ diagonally upward in the bath B3 in the suitable range to decide the staying time in the bath B3, and then, the solidified quantity of the clad material 4 is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a multi-layer cast product which produces a relatively thin clad cast product by a continuous casting method in which the clad ratio can be changed.

[0002]

2. Description of the Related Art As a general method for producing a clad steel in which dissimilar metals are joined, methods such as rolling and explosion welding are widely known. However, since these clad steel manufacturing methods generally have high manufacturing costs, some methods of directly manufacturing clad steel by a continuous casting method have been proposed from the viewpoint of manufacturing cost reduction.

For example, Japanese Patent Application Laid-Open No. 51-111458 discloses a method of continuously supplying a clad material to the inner wall of a continuous casting mold. According to this method, the clad steel can be manufactured relatively easily without significantly changing the conventional continuous casting equipment. However, with this manufacturing method, it is difficult to control the cooling of the clad material that is continuously inserted into the mold, and a product of stable quality cannot be obtained.

Further, Japanese Unexamined Patent Publication No. 62-54561 discloses a method of pouring a dissimilar metal serving as a clad material onto the surface of a cast piece which has been solidified, and welding it to the cast piece. This method also makes it possible to manufacture clad steel relatively easily without significantly changing the conventional continuous casting machine. However, in this method, since dissimilar metals are hot-melted and welded onto the already solidified slab, impurities are easily mixed in the interface between the base material and the laminated material, and the cleanliness of the interface becomes a major quality problem. .

More recently, Japanese Patent Laid-Open No. 5-2777639
As can be seen in the publication, in a general continuous casting machine, two kinds of molten steels having different compositions are poured into a mold by using two dipping nozzles, and electromagnetic waves are used to avoid mutual mixing. However, a method has been proposed in which both wide surfaces and both side surfaces of a slab are cast and wrapped with steel having one composition.

[0006]

However, although the above casting method is suitable for producing a double-sided clad steel sheet, it is impossible in principle to produce a single-sided clad steel sheet with many uses. Further, in order to obtain a large clad ratio (thickness ratio of the clad material to the thickness of the base material) using this casting method, one of the nozzles needs to have a length exceeding 2 m. Further, when changing the clad ratio, the installation position of the electromagnetic flow control device installed in order to prevent the mixing of the above two liquid phases must be greatly changed, which causes various problems in practical use.

On the other hand, as a method for efficiently casting a thin flat plate, a method of solidifying a flat plate while forming a floating free surface of the metal or alloy in a molten state on a metal bath that does not react with the target metal or alloy JP 58
-74249, JP-A-59-42163, etc. are proposed.

According to the present invention, for a clad slab having a relatively small thickness, a double-layer slab (clad slab) can be efficiently formed while keeping the interface between the base material and the laminated material (clad material) clean. It is an object of the present invention to provide a method for producing a multi-layer cast product that can be produced.

[0009]

The method for producing a multi-layer cast product according to the present invention comprises pouring molten metal as a base metal onto the surface of a molten metal bath, and then applying the molten steel as a base metal on the free surface of the molten metal bath. For forming a base material steel sheet by solidification and growth by continuous drawing, and subsequently for suspending the base material steel sheet on a molten metal bath on an extension line of the drawing direction, for a composite material having a different composition from the base material molten steel It is characterized in that it is brought into contact with steel or metal, and is drawn out in one direction while solidifying and depositing the steel or metal for the above-mentioned bonding material on one side or both sides of the base material steel sheet.

In this case, it is desirable to use a molten silver bath or a molten lead bath as the molten metal bath. Further, the molten silver bath or the molten lead bath is at least a first bath for solidification molding of the base steel sheet and a second bath for solidifying and depositing the laminated material.
It is preferable that the first and second tanks are partitioned by a weir except for the communicating portion near the liquid surface.

Furthermore, the thickness of the laminated material can be controlled by the cooling rate of the base material slab and the withdrawal rate of the slab, the temperature of the molten metal bath holding the laminated material, and the elevation angle of the slab withdrawal. preferable.

In the present invention, the clad ratio can be easily changed by using both the base material solidification forming means and the laminated material solidification forming means. That is, the feature of the present invention is that the clad ratio of the slab can be changed to an arbitrary value by controlling the solidification rate of each of the base material and the laminated material and the solidification time of the base material and the clad thickness. is there.

[0013]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. First,
The solidification forming means of the base material will be described with reference to FIG.

In FIG. 1, molten steel 1 serving as a base material is contained in a first pot 5, and molten metal 2 serving as a laminating material is contained in a second pot 6. Molten metal baths B1, B2, B3, whose interiors are divided into three, are provided from a region directly below the first pot 5 to a region directly below the second pot 6. That is, the first molten metal bath B1 is partitioned from the second molten metal bath B2 by the partition weir 10, and the second molten metal bath B2 is partitioned from the third molten metal bath B3 by the partition weir 11.

The length S2 of the second molten metal bath B2 is longer than the length S1 of the first molten metal bath B1, and the length S3 of the third molten metal bath B3 is the second molten metal bath. It is even longer than the length S2 of B2. Lengths S1 and S of the first to third baths
2, S3 are set to desired values according to specifications such as the clad ratio of the product to be manufactured. Also, these bath length S
In addition to 1 to S3, bath depth, slab drawing speed, slab drawing elevation angle θ, etc. are important factors that affect product quality.

A slab inclined withdrawal fulcrum roll 13 is provided above the entrance side of the third bath B3 and is pressed against the upper surface of the slab. The slab that is solidifying and growing is slightly bent upward by the fulcrum roll 13 and is pulled out by the pinch roll 14 at a desired pulling-out elevation angle θ.

First to third molten metal baths B1, B2, B3
Molten silver or molten lead is contained therein. The first molten metal bath B1 is provided with a temperature control device 7, the second molten metal bath B2 is provided with a temperature control device 8, and the third molten metal bath B is provided.
3 includes a temperature control device 9. Each temperature control device 7,
8 and 9 are provided with a heater and a temperature sensor, and the temperature is controlled so that the molten metal in each of the baths B1, B2 and B3 is maintained at a temperature equal to or higher than the freezing point of the molten steel 1 as the base material.

A pouring portion is formed outside the first molten metal bath B1, and the lower nozzle of the first pot 5 is inserted into the pouring portion. This lower nozzle is a sliding nozzle having a flow rate adjusting mechanism, whereby the molten steel 1 is poured into the receiving tank from the pan 5 while the flow rate is adjusted.

Further, the poured molten steel 1 overflows from the pouring portion and flows into the first bath B1 so as to cover the free surface of the molten metal. In addition, the molten metal surface in the first bath B1 is partitioned by a slag mixture prevention weir 12, and impurities such as alumina are blocked by the prevention weir 12 to prevent invasion of the downstream second and third B2 and B3. I am trying to do it.

The molten steel 1 spreads on the free surface of the molten metal bath, and the molten steel 1 also forms a free surface and is held at a predetermined thickness. The thickness of the molten steel 1 is determined by the balance between the pouring speed and the drawing speed of a thin plate that is solidified and drawn. The base material molten steel controlled to a predetermined thickness is a molten metal bath B2 controlled to a temperature equal to or higher than the melting point of silver or lead.
It solidifies and grows in the inside. Thereby, the base material steel plate 3 having a desired thickness is formed.

The plate thickness of the steel plate 3 determined by the solidification growth amount is determined by the solidification rate and the passage time in the molten metal bath B2. The solidification rate is the amount of heat removed from bath B2, in other words, bath B2.
It is determined by the temperature of 2 and the passage time is the time to stay in the bath B2, and is controlled by the length S2 of the bath B2 in the drawing direction and the drawing speed.

That is, when the drawing speed of the slab is Vc, the passage time in the bath B2 is S2 / Vc, so if the solidification constant in the bath B2 is K ₁ , the solidified casting when leaving the bath B2 The piece thickness T is approximately T = K ₁ (S2 / Vc)
^1/2 .

Base material steel plate 3 having the thickness thus determined
Passes through with one surface immersed in a molten metal (molten steel) 2 having a different composition to be a laminated material (cladding material) held on the free surface of the next molten metal bath B3. At this time, the clad material 4 is formed by solidifying and melting the molten material 2 for the joining material on the surface that is being immersed.

The slab is fulcrum roll 1 on the entry side of the third bath B3.
It is slightly bent upward by 3 and is pulled out by the pinch roll 14 at a desired pull-up elevation angle θ. here,
The slab drawing speed is set to control the plate thickness of the base steel plate 3. Therefore, in order to control the thickness (cladding thickness) of the laminated material 4, the bath B3 is pulled obliquely upward and the pull-out angle θ is adjusted to an appropriate range to determine the staying time in the bath B3. The amount of solidification of the material 4 is controlled. At that time, controlling the temperature of the bath B3 is also extremely important in determining the thickness of the laminated material 4,
The temperature range is practically within about 50 ° C. in terms of the degree of superheat with respect to the melting temperature of the laminated material 4.

On the other hand, in controlling the thickness of the laminated material, cooling control from the base material side is even more important. Specifically, as shown in FIG. 1, forced cooling is required in some form, but in this case, considering that the molten metal exists below, forced air cooling is easy.

When the above-mentioned heat removal conditions are determined and the solidification and welding speed of the composite material, that is, the solidification constant K ₂ of the composite material is determined, the thickness t (mm) of the composite material is D, the melt thickness of the composite material, and When the upward pulling angle (elevation angle) of the piece is θ, it can be expressed by the following equation (1).

T = k ₂ {(D / Vc) sin θ} ^1/2 (1) It should be noted that the surfaces of the base material and the laminated material in the molten state are kept warm and are prevented from being oxidized, and floating surfaces are present. It is desirable to cover with a predetermined flux for the purpose of absorbing material. Further, it is also desirable to cover these surfaces with an inert gas from the viewpoint of operation stability.

Further, as shown in FIGS. 2 and 3, the melt 2 for the joining material may be poured from the side surface of the strand so as not to interfere with the pulling out of the cast pieces 3 and 4 which have been solidified. Furthermore, in the case of producing a double-sided multi-layered slab, the base material slab after completion of solidification, the thickness of which has been determined, is once dipped at a melting depth of the laminated material or more, and then pulled out at a predetermined elevation angle. The mating material 4 may be solidified and adhered to the front and back surfaces of the base material.

Hereinafter, a specific example of manufacturing a cast piece will be described. (Example 1) A casting test was attempted for the purpose of producing a clad steel having a width of 800 mm using a low carbon aluminum killed steel having a carbon concentration of about 0.08% by weight as a base material and an austenitic stainless steel (SUS304) as a composite material. .

The continuous casting equipment shown in FIG. 1 was used for the casting test. Each length S1, of the molten metal baths B1, B2, B3
S2 and S3 were set to 2 m, 8 m, and 9 m, and the temperatures of the baths were kept at 1560 ° C, 1250 ° C, and 1495 ° C, respectively.

While pouring molten steel 1 as the base material into the pouring part near the first bath B1 from the first pot 5 through the dipping nozzle,
Molten metal 2 is poured from the second pot 6 through the dipping nozzle. The drawing speed is set to 5 m / min, the thickness D of the molten steel is adjusted to 20 to 25 mm, the base material steel plate 3 having substantially the same thickness is solidified and formed, and the upper drawing angle θ in the bath S3 is set to 0.5. By changing in the range of up to 2.0 °, the thickness of the laminated material (SUS304) 4 is 5 to 12 m.
I was able to obtain m.

When the cast strip drawing speed is set to 3.5 m / min, the thickness of the base steel plate 3 is 28 to 32 m.
m, the thickness of the laminated material (SUS304) 4 is 7.5
18 mm was obtained. (Example 2) Two-side solidification in bath B2 was attempted with the intention of producing a thicker base material. The flux in the bath B2 was removed, and about half of the downstream side (the bath B3 side) was subjected to forced air cooling. As a result, the coagulation constant is about 50%
It was increased, and a base material plate thickness of 80 mm was able to be secured at a drawing speed of 2.0 m / min. Further, as a result of setting the slab drawing angle θ to 1.0 °, the thickness of the laminated material 4 was 17.5 to 28 m by the forced air cooling control and the temperature control of the bath B3.
I was able to obtain m.

According to the above-mentioned embodiment, the base material plate thickness is 20 to 80 m and the interface between the base material and the laminated material is good by using simple equipment.
It has become possible to efficiently produce a clad slab having a thickness of m and a thickness of the laminated material of 5 to 28 mm.

[0034]

According to the present invention, a clad slab having a good interface between the base material and the laminated material can be manufactured with high efficiency by using a simple facility.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an outline of continuous casting equipment used in a method for producing a multi-layer cast product according to an embodiment of the present invention.

FIG. 2 is a plan view of a continuous casting facility used in the method for producing a multi-layer cast product according to the embodiment of the present invention.

3 is a vertical cross-sectional view of the equipment taken along the line III-III in FIG.

[Explanation of symbols]

1 ... Base material molten steel, 2 ... Laminated material molten metal, 3 ... Base material cast piece, 4 ...
Laminated material, 5 ... Base material molten steel holding pan, 6 ... Laminated material molten metal holding pan, 7 ... Bath B1 temperature control device, 8 ... Bath B2 temperature control device, 9 ... Bath B3 temperature control device, 10, 11 ... Bath partition weir ,
12 ... Noro mixing prevention weir, 13 ... Cast slab inclined drawing fulcrum roll, 14 ... Drawing driving roll, 15 ... Forced cooling nozzle, 16 ... Side weir.

Claims (3)

[Claims] 1. A molten base metal is poured onto the surface of a molten metal bath,
This base material molten steel is solidified and grown on the free surface of the molten metal bath to continuously draw and form the base material steel plate, and then the base material steel plate is suspended on the molten metal bath on the extension line of the drawing direction. It is characterized in that it is brought into contact with a steel or metal for a laminating material having a composition different from that of the base material molten steel, and is drawn in one direction while solidifying and depositing the steel or metal for a laminating material on one or both surfaces of the base material steel plate. And a method for producing a multi-layer cast slab. 2. A molten silver bath or a molten lead bath is used as the molten metal bath, and the molten silver bath or the molten lead bath solidifies at least a first tank for solidification molding of a base steel sheet and a laminated material. A second tank for depositing the first and second tanks, except for the communicating portion near the liquid surface,
The method for producing a multi-layer cast product according to claim 1, wherein the multi-layer cast product is partitioned by a weir. 3. The thickness of the laminated material is controlled by controlling the cooling rate of the base material slab and the withdrawal rate of the slab, the temperature of the molten metal bath holding the laminated material, and the elevation angle of the slab withdrawal. The method for producing a multi-layer cast product according to claim 1, which is characterized in that.