JP3380425B2 - Twin drum type continuous casting drum - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a twin-drum type thin plate continuous casting drum, and more particularly, to a twin-drum type thin plate continuous casting provided with a mechanism for lubricating an end surface of a cooling drum and a side dam during continuous casting. The present invention relates to a twin-drum type thin plate continuous casting drum in which a wear resistant member and a thermal strain buffering member are alternately arranged on a sliding portion of an end surface of the drum with a side dam.

[0002]

2. Description of the Related Art In recent years, attention has been focused on a continuous casting method for directly producing a thin plate having a thickness of about several mm close to the final shape from molten metal such as molten steel. In this case, the conventional multi-step hot rolling process is not required, and the rolling to the final shape may be light, so that the process and equipment can be simplified.

As one of such continuous casting methods, for example, there is a twin-drum type thin plate continuous casting method disclosed in JP-A-60-137562. In this method,
As shown in FIG. 2, a basin 3 is formed in a recess defined by a pair of cooling drums 1a and 1b and side dams 2a and 2b that rotate in opposite directions. Molten metal is poured into this pool 3 from a container such as a tundish via a pouring nozzle. The molten metal 4 contained in the molten metal pool portion 3 is cooled and solidified at the portions in contact with the cooling drums 1a and 1b to become a solidified shell. This solidified shell is accompanied by the rotation of the cooling drums 1a and 1b, and the pair of cooling drums 1a,
1b moves to a so-called drum gap portion 6, which faces each other at a position closest to each other. In the drum gap portion 6, the solidified shells formed on the surfaces of the respective cooling drums 1a and 1b are pressure-bonded to each other to form the target metal ribbon (thin plate) 5. Here, 18 is the end surface of the cooling drum.

In such a thin plate continuous casting machine, the side dams 2a, 2b are generally installed in the heat insulating material housed in the side dam case and the heat insulating material as seen in Japanese Utility Model Laid-Open No. 63-90548. And a ceramics planted on the surface of the base member corresponding to the cooling drum. At the time of casting, the side dam is pressed against the end surface of the cooling drum, and the ceramics are abraded by the cooling drum to eliminate the gap and prevent leakage of molten steel. Also, in the side weir, JP-A-61-
As disclosed in Japanese Patent No. 266160, in general,
Vibration is applied, which also promotes wear of the drum end surface.

The life of the cooling drum end surface in the thin plate continuous casting machine is determined by the heat load of the molten steel heat transferred to the cooling drum to the sliding portion of the drum end surface by heat transfer and the heat load transferred from the heating side dam to the drum end surface. It depends on the wear rate of the drum end surface coating material, which depends on Therefore, it is extremely important to improve the heat resistance of the drum end surface in order to improve the life of the drum end surface. Hitherto, in order to suppress wear of the end surface of the drum at high temperatures, wear resistant members have been applied as disclosed in JP-A-7-284883 and JP-A-6-5744.

Further, it is considered that the wear of the drum end surface is not limited to wear, and there are thermal cracks and peeling which occur in the coating material on the surface due to the heat load from the molten steel and the side weirs repeatedly applied following the rotation of the drum. . Therefore, it is effective to form a coating having excellent thermal shock resistance on the sliding surface of the cooling drum in order to suppress wear of the drum end surface.
A method for improving the thermal shock resistance of a sprayed coating in a twin-drum type continuous casting machine is disclosed in JP-A-59-76645 and JP-A-1-.
As disclosed in Japanese Patent No. 186245, there is a technique of inserting a plating layer as a thermal strain buffering member between the base material and the outermost layer of the coating film that receives heat.

[0007]

However, with the drum end surface coating materials disclosed in the above-mentioned JP-A-7-284883 and JP-A-6-5744, the wear resistance can be maintained, but the rotation of the drum does not occur. It is not possible to suppress thermal cracks and peeling that occur in the coating material on the surface due to the heat load from the molten steel and the side weir that are repeatedly added. That is, it is necessary to consider not only the wear of the drum end surface but also the crack separation due to the heat load. In addition, the above-mentioned JP-A-59-7
The thermal strain generated in the outermost surface layer portion of the sliding surface is only caused by the plating layer as the thermal strain buffering member between the base material and the surface layer material as disclosed in Japanese Patent No. 6645 and Japanese Patent Application Laid-Open No. 1-186245. Is large, and thermal cracking and peeling that occur in the coating cannot be avoided.

Therefore, an object of the present invention is to provide a twin-drum type thin plate continuous casting drum which advantageously solves such a problem and enables stable long-term casting.

[0009]

The gist of the present invention is (1)
A twin-drum type thin plate for continuously casting a thin plate while injecting molten metal into a molten metal pool formed between a pair of cooling drums and side dams and then cooling and solidifying the molten metal on the rotating peripheral surface of the cooling drum. A continuous casting drum, which is a twin-drum type thin plate continuous casting drum in which a sliding portion of an end surface of the drum with a side dam is plated with Ni to form a protective coating having a thickness of 10 to 50 μm, , The wear resistant member and the thermal strain buffering member are alternately arranged in the circumferential direction by 0.1.
A twin-drum type thin plate continuous casting drum, characterized in that they are arranged at a pitch of 0.5 mm, (2) the linear expansion coefficient of the thermal strain buffering member is 0.7 to 1 in ratio with the linear expansion coefficient of Ni ．
4. The twin-drum type thin plate continuous casting drum as described in (1) above, wherein (3) the component of the thermal strain buffering member is Ni except for unavoidable impurities. 1) The twin-drum type thin plate continuous casting drum according to 2), or 4) The component of the thermal strain buffering member is Cr.
= 15-25%, the balance being Ni and unavoidable impurities, and the twin drum type thin plate continuous casting drum according to (1) or (2) above, (5) wherein the component of the thermal strain buffering member is (2) The twin-drum type thin plate continuous casting drum according to (1) or (2) above, wherein CoCrCrY is used to remove inevitable impurities, and (6) The component of the thermal strain buffering member is CoNiCrAlY except for inevitable impurities. The twin-drum type thin plate continuous casting drum according to (1) or (2) above.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail with reference to the drawings. First, the twin-drum type thin plate continuous casting drum used in the present invention will be described with reference to FIGS. The structure of the drum end surface has a shape protruding in a ring shape in the drum axial direction with a predetermined width (sliding width) toward the side dam, and the protruding portion slides on the side dam. In the circumferential direction of the sliding part, on the center line of the sliding width,
Thermal spraying is performed so that the wear resistant members 7 and the thermal strain buffering members 8 are alternately arranged at a pitch of 0.1 to 0.5 mm. If the construction pitch of the wear resistant member 7 and the thermal strain buffering member 8 is less than 0.1 mm, the adhesion strength of the wear resistant member to the base material cannot be secured,
The coating peels off due to mechanical load during sliding. Also, 0.
If it exceeds 5 mm, the thermal strain inside the wear resistant member becomes large, resulting in the occurrence of thermal cracks and peeling. In particular, in order to ensure the quality stability of the coating during thermal spraying, the working pitch is preferably 0.3 mm or more and 0.5 mm or less.

When the wear resistant member and the thermal strain buffering member have unequal pitches, if the ratio between the wear resistant member and the thermal strain buffering member exceeds 2: 1, the buffering capacity becomes insufficient. It is desirable that the ratio be 2: 1 or less.

If the linear expansion coefficient of the thermal strain buffering member is less than 0.7 times the linear expansion coefficient of Ni, the thermal strain buffering ability will be lost and thermal cracking will occur. Further, when the linear expansion coefficient exceeds 1.4 times the linear expansion coefficient of Ni, expansion and contraction due to heat of the thermal strain buffering member are large, and conversely thermal cracking occurs, so that the linear expansion of the thermal strain buffering member. The coefficient is 0.7 to the ratio with the linear expansion coefficient of Ni.
Set to 1.4.

As a thermal strain buffer member, Ni is insufficient in wear resistance by itself, but it can be supplemented by a wear resistant member and is the same material as the base material (coefficient of linear expansion), which is preferable. It is a material.

The alloy component of Cr and Ni as the thermal strain buffering member is Cr = 15 to 25%. If the Cr component ratio exceeds 25%, the thermal shock resistance deteriorates, causing cracking of the coating film, while if the Cr content ratio is less than 15%, N
This is because it is not possible to exert the wear resistance improving effect superior to that of i.

Further, CoCrAlY, CoNiCrAl
Y is used as a heat-shielding film, has a thermal strain buffering function, and also has an adhesiveness improving function with the base material, and is therefore a preferable alloy for the thermal strain buffering member of the present invention. Al and Co
Metals such as are added for the purpose of further improving heat resistance. Further, by alloying, wear resistance can be improved as compared with Ni. Considering the directionality in which strain occurs and the softening characteristics of the material due to heat, the buffer effect of thermal strain can be further enhanced.

The wear resistant member is not particularly limited in the present invention, and the conventional WC system or Co--Cr--
A thermal spray coating material such as an Al-Y system or a Co-Mo-Cr-Si system can be appropriately selected and used. The present invention is effective regardless of the type as long as it has a structure in which the side weir is pressed against the drum end portion by the drum type continuous casting machine.

[0017]

EXAMPLES Casting tests were carried out using the present invention and comparative examples. The test conditions and results are shown in Table 1. The comparison between the case where the conventional heat buffer member is not applied and the present invention is Test No. 1 and 3
Went by. In addition, the pitch of the wear-resistant member and the heat-strain buffering member was compared within the range of the present invention and in other cases.
o. 2, 3 and 4. In addition, the effectiveness of the present invention when the material is changed is also shown in Test No. Confirmed by 5, 6, and 7.

The test results are summarized as a relationship between the casting amount and the crack generation state per unit area and are shown in FIG. In each of the examples of the present invention, it was confirmed that wear of the drum end surface due to heat was suppressed and a stable molten steel seal could be secured for a long time.

[0019]

[Table 1]

[0020]

As described in detail above, according to the present invention, there is no wear due to thermal cracks on the end surface of the drum, and stable casting can be performed for a long time. Therefore, the present invention is an industrially valuable invention. Can be said to be

[Brief description of drawings]

FIG. 1 is a diagram schematically illustrating an outline of a drum end surface of the present invention.

FIG. 2 is a perspective view schematically showing an outline of a twin-drum type thin plate continuous casting method.

FIG. 3 is a diagram showing a relationship between a casting amount and a thermal crack generation amount when the present invention is applied.

[Explanation of symbols]

1a, 1b Cooling drum 2a, 2b Side weir 3 Hot water pool 4 Molten metal 5 Metal ribbon 6 Drum gap part 7 Wear resistant members 8 Thermal strain buffer

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kazuo Hamada Inventor, Kazuo Hamada 3434 Shimada, Hikari City, Yamaguchi Pref., Nippon Steel Corp. Hikari Works (56) Reference JP-A-7-284883 (JP, A) JP 6-335751 (JP, A) JP 6-126390 (JP, A) JP 60-137562 (JP, A) JP 61-266160 (JP, A) JP 59-76645 (JP , A) JP-A-3-118945 (JP, A) JP-A-64-66049 (JP, A) Actually open 63-90548 (JP, U) Actually open flat 6-5744 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B22D 11/06 330

Claims (6)

(57) [Claims] 1. A thin plate is continuously cast while pouring molten metal into a molten metal pool formed between a pair of cooling drums and side dams, and then cooling and solidifying the molten metal on the rotating peripheral surface of the cooling drum. A twin-drum type continuous casting drum for thin plate continuous casting, in which a sliding portion of the end face of the drum with a side dam is plated with Ni and a protective coating having a thickness of 10 to 50 μm is formed on the Ni plating. A twin-drum type thin plate continuous casting drum, characterized in that, as the protective coating, wear-resistant members and thermal strain buffering members are alternately arranged in a circumferential direction at a pitch of 0.1 to 0.5 mm. 2. The twin-drum type thin plate continuous casting according to claim 1, wherein the linear expansion coefficient of the thermal strain buffering member is 0.7 to 1.4 in ratio with the linear expansion coefficient of Ni. drum. 3. The component of the thermal strain buffering member is Ni, except for inevitable impurities, and is Ni.
A twin-drum type thin plate continuous casting drum as described above. 4. The component of the thermal strain buffering member is Cr = 15 to
The twin drum type continuous casting drum according to claim 1 or 2, wherein the balance is Ni and inevitable impurities at 25%. 5. The twin-drum type thin plate continuous casting drum according to claim 1, wherein the component of the thermal strain buffering member is CoCrAlY except for inevitable impurities. 6. The twin-drum type thin plate continuous casting drum according to claim 1, wherein the component of the thermal strain buffering member is CoNiCrAlY except for inevitable impurities.