JPH09271901A - Method for continuously casting clad cast slab - Google Patents

Abstract

(57) Abstract: A clad slab having a composition of a surface layer portion and an inner layer portion different from each other is manufactured industrially at low cost and stably without breaking the clad material plate by continuous casting. SOLUTION: The clad material is continuously manufactured by injecting the molten steel 3 into a mold 4 of a continuous casting machine for continuously casting a steel material from molten steel and supplying a clad material plate 5 along the inner surface of the mold 4. In doing so, a method for continuous casting of clad slabs is characterized in that a clad material plate 5 having a flux having a liquidus temperature of 1100 ° C. or more and 1300 ° C. or less attached to the surface in contact with the inner surface of the mold 4 is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting method for clad slabs in which the surface layer portion and the inner layer portion have different compositions.

[0002]

2. Description of the Related Art Regarding a continuous casting method for clad slabs, a vertical mold provided directly under a tundish is used.
The clad material plate is vertically supplied so as to be in contact with the inner surface of the mold, continuously supplied, and at the same time, molten steel in the tundish is injected into the mold through the clad material plate, From within the mold, the unsolidified clad slab with the clad material plate welded to the outer surface is continuously drawn out, after which the unsolidified clad slab is cooled,
A method for producing a clad slab by continuous casting, which comprises casting a clad slab, is disclosed in Japanese Patent Laid-Open No. 59-15653.
No. 8 discloses this.

[0003]

When the clad material plate is between the mold and the solidified shell, the clad material plate is pressed against the mold by molten steel static pressure. At this time, in the above method, since there is no lubricant between the clad material plate and the mold, excessive tensile stress acts on the clad material plate, which may cause the clad material plate to deform or even break. Therefore, there is a problem in that the quality of the clad material portion in the cast slab is uneven and the quality is deteriorated, and the operation is forced to be interrupted. Therefore, it is an object to improve the lubrication between the clad material plate and the mold and reduce the frictional force.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been invented in order to advantageously solve the above-mentioned problems, and its gist is to provide molten steel in a mold of a continuous casting machine for continuously casting steel from molten steel. In order to continuously produce a clad material by injecting and supplying a clad material plate along the inner surface of the mold, a clad material plate with a flux attached is used for the surface in contact with the inner surface of the mold. A continuous casting method for a clad slab, which is characterized in that a liquidus temperature of 1100 ° C. or higher and 1300 ° C. or lower is used as the flux.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing an embodiment of the present invention. In FIG. 1, tundish 1
Thus, the molten steel 3 is injected into the mold 4 via the immersion nozzle 2. At the same time, the clad material plate 5 is supplied via the guide roll 6 so as to contact the inner surface of the mold. At this time, the clad material plate is welded to the solidified shell 7 by the heat supply from the molten steel in the mold. further,
The flux attached to the surface of the clad material plate that contacts the inner surface of the mold melts and acts as a lubricant between the mold and the clad material plate. Therefore, the frictional force between the clad material plate and the mold does not become excessive and the clad material plate does not break.

In order for the flux adhered to the surface of the clad material plate that contacts the inner surface of the mold to melt and act as a lubricant between the mold and the clad material plate, the liquidus temperature must be within an appropriate range. is important. If the liquidus temperature is too high, it will not melt in the mold and will not act as a lubricant. On the other hand, if the liquidus temperature is too low, the clad material plate is heated by the radiant heat from the molten steel before being inserted into the mold, melts, and flows down from the surface of the clad material plate. From these, the liquidus temperature of the flux attached to the surface of the clad material plate is 1100 ° C or more and 1300 ° C or more.
It is desirable to do the following.

As a method for adhering the flux to the surface of the clad material plate, there are a thermal spraying method, a powder sintering method, a method of dissolving the flux in an organic solvent, spraying and then heating, and the same effect can be obtained by either method. To be

[0008]

【Example】

(Example 1) Molten steel in a tundish was injected into a mold through an immersion nozzle, and at the same time, a clad material plate having a thickness of 3 mm was continuously supplied so as to contact the inner surface of the mold. Molten steel in the tundish is steel for general structural materials SS4
1 and the clad material plate is SUS304. The composition of the clad material plate on the surface that contacts the inner surface of the mold is% by weight.
In _{SiO 2: 35~45%, CaO:} 20~25%, A
_{l 2 O 3: 2~5%,} CaF 2: 10~20%, Na 2
_{O: 10~15%, Fe 2 O} 3: 0~1%, MgO: 1
A flux consisting of ~ 2% and unavoidable impurity elements was deposited. The liquidus temperature of this flux is 1150 to 1300 ° C., although it depends on the composition. The flux deposition thickness on the surface of the clad material plate was 1 mm, and it was deposited by a thermal spraying method. Comparative Example 1 is a case where the flux was not attached to the surface of the clad material plate.

In Comparative Example 1, the clad material plate broke during the casting and the casting had to be interrupted, whereas the method of the present invention did not break the clad material sheet.
Stable casting is possible.

(Example 2) Molten steel in a tundish was injected into a mold through a dipping nozzle, and at the same time, a clad material plate having a thickness of 3 mm was continuously supplied so as to contact the inner surface of the mold. The molten steel in the tundish is steel for general structural materials SS41, and the clad material plate is SUS304. On the surface of the clad material plate that contacts the inner surface of the mold, the composition is wt%, SiO ₂ : 35 to 45%, CaO: 20 to
_{25%, Al 2 O 3:} 2~5%, CaF 2: 10~20
%, Na ₂ O: 10 to 15%, Fe ₂ O ₃ : 0 to 1%,
A flux composed of MgO: 1 to 2% and an unavoidable impurity element was adhered. The liquidus temperature of this flux is 1150 to 1300 ° C., although it depends on the composition.

In Comparative Example 2, the composition of the flux deposited on the surface of the clad material plate is wt% and SiO ₂ : 10 to 1
5%, CaO: 50~60%, Al 2 O 3: 2~5%,
CaF ₂ : 1-5%, Na ₂ O: 1-5%, Fe
₂ O ₃ : 0 to 1%, MgO: 1 to 2% and an unavoidable impurity element. Although the liquidus temperature of this flux varies depending on the composition,
00 ° C.

In Comparative Example 3, the composition of the flux deposited on the surface of the clad material plate was wt% and SiO _{2 was} 40 to 5.
0%, CaO: 20~30%, Al 2 O 3: 10~20
%, CaF ₂ : 20 to 25%, Na ₂ O: 10 to 20
_{%, Fe 2 O 3: 0~1} %, MgO: it was made from 1-2% and unavoidable impurity elements. The liquidus temperature of this flux varies depending on the composition, but it is 950 to 1050.
° C. In each of the method of the present invention, Comparative Example 2 and Comparative Example 3, the adhesion thickness of the flux was 1 mm, and the flux was applied by the thermal spraying method.

In Comparative Example 2, the flux deposited on the surface of the clad material plate was not dissolved in the mold, did not function sufficiently as a lubricant, and the friction between the clad material plate and the mold was large, and the clad material plate It broke. In Comparative Example 3, before the clad material plate was inserted into the mold, the flux melted due to the radiant heat from the molten steel and flowed down, which did not function as a lubricant and the clad material plate broke. On the other hand, according to the method of the present invention, stable casting is possible without breaking the clad material plate.

[0014]

INDUSTRIAL APPLICABILITY By using the method of the present invention, it is possible to improve the quality of the slab and to stabilize the operation when producing a slab with different compositions of the inner layer portion and the surface layer portion by continuous casting. It will be possible.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an example of an embodiment of the present invention.

[Explanation of symbols]

 1 Tundish 2 Immersion nozzle 3 Molten steel 4 Mold 5 Clad material plate 6 Guide roll 7 Solidification shell

Claims (2)

[Claims] 1. A molten steel (3) is poured into a mold (4) of a continuous casting machine for continuously casting a steel material from molten steel, and a clad material plate (5) is provided along the inner surface of the mold (4).
The continuous casting method for clad slabs, characterized in that the clad material plate (5) having flux adhered to the surface in contact with the inner surface of the mold (4) is used for continuously producing the clad material by supplying . 2. The flux has a liquidus temperature of 1
The continuous casting method for clad slabs according to claim 1, wherein a temperature of 100 ° C or higher and 1300 ° C or lower is used.