JP2001205399A - Cooling drum for twin-drum type continuous casting of thin slab and continuous casting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling drum which is enhanced in a thermal insulating effect and is prolonged in the life of the cooling drum by imparting a single layer or plural layers of plating layers containing metal oxide layers in-between to the drum surface of the cooling drum for twin-roll type continuous casting and method for manufacturing the same. SOLUTION: The cooling drum for twin-drum type continuous casting of a thin slab has the three-layered plating layers consisting of the first plating layer of thickness of 100 to 500 μm which is formed of metal or alloy of any >=1 kind among Ni, Co, Co-Ni alloy, Ni-W alloy or Co-Ni-W alloy, the second plating layer which forms the metal oxide layer consisting of the metal or alloy of any >=1 kind among the Ni, Co, Co-Ni alloy, Ni-W alloy or Co-Ni-W alloy suspended with alumina particles of <=500 μm in diameter at a thickness of 500 to 1,000 μm and the third plating layer of thickness of 100 to 1,000 μm formed of the metal or alloy of any >=1 kind among the Ni, Co, Co-Ni alloy, Ni-W alloy or Co-Ni-W alloy on the second plating layer on the surface of the cooling drum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum structure of a cooling drum used for continuously casting a ribbon from a molten metal by a pair of cooling drums.

[0002]

2. Description of the Related Art In the field of continuous casting of metal, there is a twin-drum strip continuous casting method using a pair of cooling drums as a method of continuously casting a ribbon having a shape close to the final shape.
In this casting method, as shown in FIG. 1, molten metal M is formed by a pair of cooling drums 1-a, 1-b and side dams 2-a, 2-b for sealing the molten metal between these cooling drums. It is supplied from the tundish to the hot water pool 3 formed therebetween,
Next, the heat is removed through the cooling drums 1-a and 1-b, and a solidified shell 4 is formed on the peripheral surface of the cooling drums 1-a and 1-b. It is sent out as a thin ribbon S. The cooling drum used in the casting method has a problem that the life of the drum is short due to thermal fatigue due to repeated contact and non-contact with molten steel. As a method of alleviating the cooling of the drum when it is not in contact with molten steel, Japanese Patent Application Laid-Open No. 5-92239 discloses a method.
As disclosed in Japanese Unexamined Patent Publication (Kokai) No. H11-209, there is known a method of providing a heating means for heating the outer surface of a cooling drum. Also,
As disclosed in Japanese Patent Application Laid-Open No. 7-328749, the surface layer of the casting surface is formed from a pure Ni plating layer, a Ni-dissimilar material dispersed plating layer containing Fe, W or nonmetal, or a Co-Ni plating layer. Of low thermal conductivity material, the inner layer is made of silver copper or Cr-Zr copper, and has a multilayer structure with high thermal conductivity material. In addition, irregularities are formed at the interface between low thermal conductivity material and high thermal conductivity material. In addition, there has been proposed a cooling drum having a smooth casting surface. Furthermore, a cooling drum has been proposed in which after the surface of the cooling drum is subjected to alloy plating or the like, an uneven portion having a certain depth is formed on the surface layer portion, and the surface of the casting surface of the cooling drum is made smooth. I have.

[0003]

However, the conventional cooling drum described above has a problem that the life of the drum is short due to thermal fatigue caused by repeated contact and non-contact with molten steel. Mainly, the service life of both the inside of the drum made of copper alloy and the plating layer on the surface is a problem, but the plating layer can be repaired by grinding, re-plating, etc., but the inside of the drum cannot be easily repaired. The service life is the service life of the drum body. In order to extend the life, it is necessary to increase the durability by improving the strength of the drum side, or to reduce the heat load by relaxing the heat reception from the molten steel. The present inventors have paid attention to the latter, and have completed the present invention for the purpose of reducing the heat flux in the drum, and as a result, significantly extending the life of the drum.

[0004]

SUMMARY OF THE INVENTION In order to solve the disadvantage that the life of a conventional cooling drum for twin-drum thin cast slab casting is short, the present invention provides a plating method containing metal oxide particles on the surface of the cooling drum. A cooling drum for continuous casting of twin-type thin cast slab having a layer and a casting method thereof, the gist of which is as follows.

(1) A twin-drum type cooling drum for continuous casting of thin slabs, comprising a metal oxide layer containing metal oxide particles within 2 mm from the surface of the surface of the cooling drum. Cooling drum for continuous casting of thin cast slabs. (2) In the cooling drum for twin-drum thin cast continuous casting, the surface layer of the cooling drum is made of at least one of Ni, Co, Co-Ni alloy, Ni-W alloy and Co-Ni-W alloy. A cooling drum for twin-drum thin cast continuous casting, comprising a metal oxide layer containing metal oxide particles within 2 mm from the surface of the surface layer.

(3) In a twin drum type cooling drum for continuous casting of thin slabs, the surface layer of the cooling drum is made of Ni, Co, Co.
-A metal oxide layer comprising at least one of a Ni alloy, a Ni-W alloy, and a Co-Ni-W alloy, having a metal oxide layer containing metal oxide particles within 2 mm from the surface of the surface layer, and A cooling drum for continuous casting of a twin-drum thin cast slab, wherein the area ratio of oxide particles is 10 to 70%.

(4) In a twin-drum type cooling drum for continuous casting of thin slab, the surface layer of the cooling drum is made of Ni, Co, Co.
-A metal oxide layer comprising at least one of a Ni alloy, a Ni-W alloy and a Co-Ni-W alloy, having a metal oxide layer containing metal oxide particles within 2 mm from the surface of the surface layer; A twin-drum type thin-cast continuous casting cooling drum, characterized in that the area ratio of particles of the product is 10 to 70% and the diameter of the metal oxide particles is 500 μm or less.

(5) In a twin drum type cooling drum for continuous casting of thin slabs, Ni, Co, Co-
One or more metals or alloys of Ni alloy, Ni-W alloy, Co-Ni-W alloy, with a thickness of 100 to 500 m
A first plating layer and a diameter of 50 on the first plating layer.
Ni, Co, Co-Ni alloy, Ni-W alloy in which alumina particles of 0 μm or less are suspended at an area ratio of 10 to 70%,
A second plating layer in which a metal oxide layer made of any one or more metals or alloys of a Co—Ni—W alloy is formed to a thickness of 500 to 1000 μm, and Ni, Co on the second plating layer , Co-Ni alloy, Ni-W alloy, Co
A cooling drum for twin-drum thin cast slab continuous casting, comprising a three-layer plating layer comprising a third plating layer having a thickness of 100 to 1000 μm and made of at least one metal or alloy of a Ni-W alloy. .

(6) The above (1), (2), (3),
(2) A twin-drum thin cast slab continuous casting method, comprising casting using the cooling drum according to any one of (4) and (5).

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings. FIG. 2 is a cross-sectional view of a cooling drum in a conventional method, in which Ni, Co or Co-Ni, Ni is formed on the surface of a sleeve 5 made of Cu or a Cu alloy of the cooling drum 1-a.
-W, Co-Ni-W alloy having a thickness of about 1
After applying the plating layer 6 of 2 mm, the surface of the plating layer 6 is subjected to chiseling, shot,
A large number of depressions (dimples) 12 having a constant depth and a diameter of 200 to 1000 μm are formed by electric discharge machining, laser machining, or etching. However, the heat flux is not remarkably reduced by the gas gap due to these depressions, and the life of the drum is shortened by the high heat load of the drum.

Therefore, the present inventors have found that the heat flux of the drum, that is, the heat load can be significantly reduced by providing an oxide layer having a heat insulating effect on the plating layer of the cooling drum. That is, after the first plating layer is formed on the surface of the cooling drum, alumina particles having a diameter of 500 μm or less are formed on the first plating layer on the surface parallel to the peripheral surface of the drum.
A metal oxide layer made of one or more metals or alloys of any one of Ni, Co, Co-Ni alloy, Ni-W alloy, and Co-Ni-W alloy suspended at 10 to 70% has a thickness of 50%.
The problem of the drum life could be solved by forming a metal oxide layer serving as a second plating layer formed at 0 to 1000 μm.

As shown in FIG. 3, the cooling drum according to the present invention first has Ni, Co,
A first plating layer 7 having a thickness of 100 to 500 μm and made of at least one of a Co—Ni alloy, a Ni—W alloy, and a Co—Ni—W alloy is formed. This is a plating layer usually applied to the cooling drum. Next, on this first plating layer, Ni, Co, Co—Ni alloy, Ni, in which alumina particles 8 having a diameter of 500 μm or less are suspended at an area ratio of 10 to 70% in a plane parallel to the peripheral surface of the drum. -W alloy, Co-
A metal oxide layer 9 which is made of at least one kind of metal or alloy of a Ni-W alloy and has a thickness of 500 to 1000 μm and is a second plating layer is formed. On the metal oxide layer containing the metal oxide particles, Ni, Co, Co—Ni alloy, Ni—W alloy having the same composition as the first plating layer 7,
Third plating layer 1 having a thickness of 100 to 1000 μm and made of at least one metal or alloy of a Co—Ni—W alloy
0 is formed on the surface of the third plating layer 10 as in FIG.

In the present invention, the reason why the diameter of alumina particles contained in the second plating layer is 500 μm or less is as follows.
If the diameter of the alumina particles is more than 00 μm, it is difficult to disperse the alumina uniformly in the plating bath, and uniform plating cannot be performed. This is because the stress resulting from the difference in the amount increases, and cracks occur in the plated metal, thereby shortening the life of the drum. Further, the thickness of the metal oxide layer forming the plating layer in the present invention is 500
The reason why the thickness is limited to about 1000 μm and the area ratio: 10 to 70% is that when the thickness of the metal oxide layer is 500 μm or less and the area ratio is 10% or less, the effect of reducing heat flux cannot be sufficiently obtained. When the thickness of the metal oxide layer is 1000 μm or more and the area ratio is 70% or more, the heat insulation effect is large, so that the temperature of the plating surface is increased, and the surface is softened and thermal cracks are generated. Further, in order to obtain an area ratio of the metal oxide of 70% or more, the concentration of the oxide suspended in the plating bath must be increased. As a result, the progress of plating is easily hindered and uniform plating is performed. Because you can't.

By using three plating layers including a metal oxide layer as described above, a plating layer having extremely excellent heat insulating properties can be formed. Of course, the composition of the metal or alloy of the first plating layer, the second plating layer, and the third plating layer may be the same or different, respectively, but the plating of different metals or alloys may be performed. It is preferably a layer.

[0015] The life of the cooling drum manufactured in this way is extended several times or more than the conventional one, and the heat flux of the conventional cooling drum is 20 to 20 times that of the conventional one.
It can be seen that the heat insulating effect is reduced by 34%.

[0016]

(Example 1) 300 μm thick on the peripheral surface of a cooling drum having a drum diameter of 1200 mm and a drum width of 800 mm
Was formed, and a second plating layer was formed with a thickness of 700 μm by Ni plating in a state where alumina particles having a diameter of 10 μm were suspended at 5 g / l on the plating layer. The area ratio occupied by the alumina particles at this time was 15% in the area parallel to the peripheral surface of the drum. Furthermore,
On this second plating layer, a 500 μm thick Co-Ni alloy
The third plating layer was applied. The total plating thickness on the cooling drum surface is 1500 μm. Finally, dimples were formed by performing shot blasting with a steel ball having a diameter of 2 mm from above these plating layers. As a result, as shown in FIG. 4, the heat flux in the first embodiment is reduced by about 20% as compared with the conventional comparative example in which the surface of the cooling drum is simply plated with Ni having a thickness of 1 mm and the surface is dimpled. Further, as shown in FIG. 5, the service life of the cooling drum could be extended about 3.4 times as compared with the conventional comparative example.

Example 2 A 300 μm first plating layer was formed on the peripheral surface of a cooling drum having the same drum size as in Example 1, and then 15 g / l of alumina particles having a diameter of 10 μm were formed on the plating layer. In the suspended state, Ni plating was formed to a thickness of 700 μm to form a second plating layer. The area ratio occupied by the alumina particles at this time was 35% in the area parallel to the peripheral surface of the drum. Further, a third plating layer was formed on the second plating layer with a thickness of 500 μm using a Co—Ni alloy. The total plating thickness on the cooling drum surface is 1500 μm. Finally, dimples were formed by performing shot blasting with a steel ball having a diameter of 2 mm from above these plating layers. As a result, as shown in FIG. 4, the heat flux in the first embodiment is reduced by about 25% as compared with the conventional comparative example in which the surface of the cooling drum is simply plated with Ni having a thickness of 1 mm and the surface is dimpled. Further, as shown in FIG. 5, the life of the cooling drum is about 4 times longer than that of the comparative example.
Could be extended twice.

Example 3 A first plating layer of 300 μm was formed on the peripheral surface of a cooling drum having the same drum size as that of Example 1, and then 30 g / l of alumina particles having a diameter of 10 μm were formed on the plating layer. In the suspended state, Ni plating was formed to a thickness of 700 μm to form a second plating layer. At this time, the area ratio occupied by the alumina particles was 50% in the area parallel to the peripheral surface of the drum. Further, a third plating layer was formed on the second plating layer with a thickness of 500 μm using a Co—Ni alloy. The total plating thickness on the cooling drum surface is 1500 μm. Finally, dimples were formed by performing shot blasting with a steel ball having a diameter of 2 mm from above these plating layers. As a result, as shown in FIG. 4, the heat flux in the first embodiment is reduced by about 34% as compared with the conventional comparative example in which the surface of the cooling drum is simply plated with Ni having a thickness of 1 mm and the surface is dimpled. Further, as shown in FIG. 5, the life of the cooling drum could be extended about 4.7 times as compared with the conventional comparative example.

[0019]

As described above, according to the present invention, by providing a metal oxide layer inside a drum surface layer of a twin-roll type continuous casting cooling drum, the heat insulating effect can be enhanced and the life of the cooling drum can be extended. Will be possible.

[Brief description of the drawings]

FIG. 1 is a perspective view of a twin-roll continuous casting apparatus.

FIG. 2 is an enlarged partial cross-sectional view of a conventional cooling drum.

FIG. 3 is an enlarged partial cross-sectional view of a cooling drum according to the present invention.

FIG. 4 is a diagram showing measurement results of heat flux in an example according to the present invention and a comparative example.

FIG. 5 is a diagram showing a comparison of a cooling drum life between an example according to the present invention and a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cooling drum 2 ... Side weir 3 ... Hot water pool 4 ... Solidified shell 5 ... Sleeve 6 ... Plating layer 7 ... First plating layer 8 ... Alumina particles 9 ... Metal oxide layer (second plating layer) 10 ... Third plating Layer 12: Dimple S: Thin ribbon

Claims (6)

[Claims] 1. A twin drum type cooling drum for continuous casting of thin cast slabs, comprising a metal oxide layer containing metal oxide particles within 2 mm from the surface of the surface of the cooling drum. Cooling drum for continuous casting of thin slabs. 2. A cooling drum for twin-drum thin cast continuous casting, wherein the surface layer of the cooling drum is Ni, Co, Co-N.
an i-alloy, a Ni-W alloy, or a Co-Ni-W alloy, comprising a metal oxide layer containing metal oxide particles within 2 mm from the surface of the surface layer. Drum type cooling drum for continuous casting of thin slabs. 3. A cooling drum for continuous casting of a twin-drum thin cast slab, wherein the surface layer of the cooling drum is Ni, Co, Co-N.
an i-alloy, a Ni-W alloy, a Co-Ni-W alloy, a metal oxide layer containing metal oxide particles within 2 mm from the surface of the surface layer, and the metal oxide A twin-drum cooling drum for continuous casting of thin slabs, wherein the area ratio of particles of the product is 10 to 70%. 4. A cooling drum for twin-drum thin cast continuous casting, wherein the surface layer of the cooling drum is Ni, Co, Co-N.
an i-alloy, a Ni-W alloy, or a Co-Ni-W alloy, comprising a metal oxide layer containing metal oxide particles within 2 mm from the surface of the surface layer; Wherein the area ratio of the particles is 10 to 70% and the diameter of the metal oxide particles is 500 μm or less. 5. A cooling drum for twin-drum thin cast slab continuous casting, wherein Ni, Co, Co-Ni is provided on the surface of the cooling drum.
Any one of an alloy, a Ni-W alloy, and a Co-Ni-W alloy
A first plating layer of at least one kind of metal or alloy having a thickness of 100 to 500 μm, and a 500 μm diameter on the first plating layer;
Ni, Co, Co-Ni alloy, Ni-W alloy, Co
A second plating layer in which a metal oxide layer made of any one or more kinds of metals or alloys of a Ni-W alloy is formed with a thickness of 500 to 1000 μm;
i, Co, Co-Ni alloy, Ni-W alloy, Co-Ni
-W alloy and one or more metals or alloys with a thickness of 1
A cooling drum for twin-drum thin cast continuous casting, comprising a three-layer plating layer comprising a third plating layer having a thickness of 00 to 1000 μm. 6. A twin-drum thin cast slab continuous casting method comprising casting using the cooling drum according to any one of claims 1, 2, 3, 4 and 5.