JP2011031247A - Mold for continuous casting and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold for continuous casting capable of achieving improvement of tenacity and achieving further improvement of thermal shock resistance so as to prolong the life of the mold, and also to provide a method for manufacturing the same. <P>SOLUTION: In the mold for continuous casting and the method for manufacturing the same, a base plating layer 12 and a sprayed coating 13 on which surface roughening process are carried out are sequentially formed at a molten steel contact surface side. The sprayed coating 13 is formed by mixing a granular cermet material A composed of ≥10 mass% and ≤30 mass% of Cr<SB>3</SB>C<SB>2</SB>, ≥5 mass% and ≤15 mass% of Ni, and the balance WC with a granular material B composed of Ni or Ni based alloy. A thermal spray particle, in which the material B occupies ≥5 mass% and ≤30 mass% of a whole, is thermally sprayed by a flame spray machine 14, and the material B is made to exist at the grain boundary of the cermet material A. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a continuous casting mold used for manufacturing steel and the like and a manufacturing method thereof, and more particularly to a continuous casting mold excellent in heat resistance, corrosion resistance, and wear resistance and a manufacturing method thereof.

Conventionally, as a casting mold for continuous casting whose inner surface is thermally sprayed to improve wear resistance, for example, there is a mold disclosed in Patent Document 1. In the production of this mold, the surface of a base material made of a precipitation hardening type copper alloy (hereinafter also referred to as a base material copper plate) was subjected to base plating such as Ni, and a Ni—Cr based self-fluxing alloy was sprayed thereon. Thereafter, it is heated to about 1000 ° C. As a result, a diffusion layer is formed between the base copper plate and the base Ni plating layer and between the base Ni plating layer and the sprayed coating, and is bonded metallurgically, thereby providing a strong resistance on the base copper plate. A thermally sprayed coating having wear properties is formed.

However, as described above, when the base copper plate after thermal spraying is heated to about 1000 ° C., the base copper plate is deformed. For this reason, it is necessary to perform a strain relief operation on the base copper plate, but even if the strain relief is performed, it may not be incorporated into the back frame of the continuous casting mold. There is a problem that the flatness of the copper plate is inferior.
Furthermore, it is necessary to perform an age hardening heat treatment to recover the strength of the base copper plate, and there is a problem that the manufacturing process is extremely complicated and diverse. Here, it is conceivable that heat treatment is not performed after thermal spraying of a Ni—Cr self-fluxing alloy. In this case, the adhesion with the base copper plate is 0.20 to 0.29 MPa ( ^{2 to 3} kg / mm ^2). ) And is difficult to use for a long time.

Therefore, the inventor previously applied for a continuous casting mold that can be manufactured without performing heat treatment, as shown in Patent Document 2. Specifically, the thermal spray coating includes 10 to 90% by mass of a nickel-based alloy material and wear-resistant ceramics, and is composed of 90 to 10% by mass of a cermet material corresponding to the proportion of the nickel-based alloy material. In this mold, a nickel-based alloy material and a cermet material are sprayed at the same location simultaneously using independent flame sprayers.

Japanese Examined Patent Publication No. 61-15758 JP-A-10-71454

However, the conventional mold cannot be provided with thermal shock resistance that meets current needs.
Cited Document 2 describes a cermet material using various wear-resistant ceramics. In particular, when WC / Co is used for wear-resistant ceramics, it is compared with a single Ni—Cr-based self-fluxing alloy. It is described that the wear resistance of the mold can be improved, and the life of the mold can be extended most. This WC / Co is a material with excellent thermal shock resistance, but even if a thermal spray coating using this WC / Co is used, no further improvement in toughness can be expected and thermal shock resistance cannot be improved. It was easy to peel off, and the life of the mold could not be further extended.

Further, in the cited document 2, since two flame sprayers for respectively spraying the nickel-based alloy material and the cermet material are used for forming the sprayed coating, the thermal spraying in which the nickel-based alloy material and the cermet material are uniformly dispersed is used. There was a fear that a film could not be formed. For this reason, the portion where the density of the cermet material is high has low toughness, and there is a fear that the thermal shock resistance is lowered.
In addition, since two flame sprayers are used, there is a problem that workability when forming the sprayed coating is poor, and the equipment cost of the flame sprayer is increased, which is uneconomical.

The present invention has been made in view of such circumstances, and provides a continuous casting mold capable of improving toughness and further improving thermal shock resistance and, as a result, extending the life of the mold, and a method for manufacturing the same. For the purpose.

The continuous casting mold according to the first invention that meets the above-mentioned object is a continuous casting mold in which a base plating layer and a sprayed coating that have been roughened are sequentially formed on the molten steel contact surface side.
The thermal spray coating is composed of a granular cermet material A composed of Cr ₃ C ₂ : 10% by mass to 30% by mass, Ni: 5% by mass to 15% by mass, and the balance WC, and a granular cermet material composed of Ni or a Ni-based alloy. The material B is formed by mixing with the material B, and sprayed with 5 flame% or more and 30 weight% or less of the whole material B with a flame spraying machine, and the material B exists at the grain boundary of the cermet material A Formed.

In the continuous casting mold according to the first invention, the base plating layer is made of Ni, Co, Fe, or an alloy based on any one or two of these, and the surface of the base plating layer is The roughness is preferably 50 μm or more and 150 μm or less by the roughening treatment.
In the continuous casting mold according to the first invention, the thickness of the thermal spray coating is preferably 0.1 mm or more and 1 mm or less.
In the continuous casting mold according to the first aspect of the present invention, the flame sprayer may be a high-speed flame sprayer that sets the velocity of the spray particles to 600 m / sec or more.

A method for manufacturing a continuous casting mold according to the second invention in accordance with the above object is a method for manufacturing a continuous casting mold in which a rough plating treatment and a thermal spray coating are sequentially formed on the molten steel contact surface side. In
Mixing granular cermet material A composed of Cr ₃ C ₂ : 10 mass% or more and 30 mass% or less, Ni: 5 mass% or more and 15 mass%, and the balance WC, and granular material B composed of Ni or Ni-based alloy In addition, the thermal spray coating is formed by spraying thermal spray particles, which are 5% by mass or more and 30% by mass or less of the whole, with the material B using a flame spraying machine, and the material B is present at the grain boundaries of the cermet material A. Form.

In the method for producing a continuous casting mold according to the second invention, the undercoat layer is made of Ni, Co, Fe, or an alloy based on any one or more of these, and the undercoat layer It is preferable to form the thermal spray coating after the surface roughening treatment is performed to make the surface roughness 50 μm or more and 150 μm or less.
In the method for producing a casting mold for continuous casting according to the second invention, a high-speed flame sprayer is used as the flame sprayer, and the velocity of the spray particles is preferably 600 m / second or more.

The casting mold for continuous casting and the manufacturing method thereof according to the present invention are composed of a granular cermet material A composed of Cr ₃ C ₂ , Ni, and the balance WC with a thermal spray coating adjusted to a predetermined ratio, and Ni or a Ni-based alloy. The sprayed particles formed by mixing with the granular material B and having 5% by mass or more and 30% by mass or less of the entire material B as the material B are sprayed by a flame spraying machine so that the material B exists at the grain boundary of the cermet material A. Therefore, the toughness can be improved and the thermal shock resistance can be improved. Therefore, peeling of the sprayed coating to be formed can be suppressed, and the life of the mold can be further extended.

Further, when the base plating layer is made of Ni, Co, Fe, or an alloy based on any one or more of these, a part of the sprayed particles sprayed by the flame spraying machine is It can penetrate into the surface layer and secure the retention force of the spray particles. Here, since the roughening treatment is further performed, the adhesion strength of the thermal spray coating can be improved. In addition, since this roughening process has a roughness of 50 μm or more and 150 μm or less, the adhesion of the sprayed coating can be enhanced while suppressing variations in the thickness of the sprayed coating.

When the thickness of the sprayed coating is 0.1 mm or more and 1 mm or less, the thickness of the sprayed coating can be set to an optimum thickness that can suppress the peeling of the sprayed coating and further increase the life of the mold.
Furthermore, when the flame sprayer is a high-speed flame sprayer that makes the speed of the spray particles 600 m / sec or more, the adhesion of the sprayed coating to the underlying plating layer can be further increased.

It is explanatory drawing which shows the thermal spraying condition of the casting mold for continuous casting which concerns on one embodiment of this invention. It is a partial expanded sectional view of the same casting mold. (A) is the partial expansion schematic diagram of the sprayed coating of the casting mold for continuous casting, (B) is the partial enlarged schematic diagram of the sprayed coating formed only with the cermet material A. It is explanatory drawing of the evaluation method of a thermal shock resistance.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
As shown in FIGS. 1, 2 and 3A, a continuous casting mold according to an embodiment of the present invention has a cooling member 10 in which a space portion penetrating in the vertical direction is formed. The slab is manufactured while supplying molten steel to the space and cooling it. The cooling member 10 includes a base material 11 made of copper or a copper alloy (for example, Cu—Cr—Zr), and a base plating layer 12 and a thermal spray coating 13 are sequentially formed on the molten steel contact surface side. ing. Details will be described below.

As shown in FIGS. 1 and 2, a base plating layer 12 that has been subjected to a roughening treatment is formed on the molten steel contact surface side of the base material 11. The base plating layer 12 has an anchor effect, which is the principle of adhesion of thermal spraying, obtained from a soft base material made of copper or a copper alloy, and in particular, Ni, Co, Fe, or any one or two of these It is preferable to consist of an alloy having the above as a base material.
In the roughening treatment performed on the base plating layer 12, the surface roughness (Rz) of the base plating layer 12 is 50 μm or more and 150 μm or less (preferably, the lower limit is 70 μm, the upper limit is 120 μm, and further 100 μm). Is preferred. Here, when the roughness is out of the range of 50 μm or more and 150 μm or less, the adhesion of the thermal spray coating to the underlying plating layer becomes less than 98 MPa (10 kg / mm ² ) and becomes too small.

A thermal spray coating 13 is formed on the base plating layer 12.
The thermal spray coating 13 is formed by mixing thermal spray particles formed by mixing a granular cermet material A composed of Cr ₃ C ₂ , Ni, and the balance WC with a granular material B composed of Ni or a Ni-based alloy. It is formed by thermal spraying.
Here, as the Ni-based alloy used for the material B, for example, any one of Hastelloy, Inconel, Ni—Cr, or MCrAlY (M: Ni or Ni—Co) can be used. Ni is particularly preferred. Note that the material B may contain inevitable impurities.

The thickness of the sprayed coating 13 is not particularly limited, but is preferably formed densely (with a filling rate of 90% or more, more preferably 95% or more) in a range of 0.1 mm to 1 mm.
Here, when the thickness of the sprayed coating is less than 0.1 mm, the thickness of the sprayed coating is too thin and the service life of the mold becomes too short. On the other hand, when the thickness of the thermal spray coating exceeds 1 mm, the thermal spray coating is too thick and the thermal spray coating is easily peeled off from the cooling member.
From the above, the thickness of the sprayed coating 13 to be formed is preferably 0.1 mm or more and 1 mm or less, but the lower limit is preferably 0.2 mm, more preferably 0.3 mm, and the upper limit is more preferably 0.7 mm. .

The spray particles are formed by mixing a granular cermet material A and a granular material B (5% by mass to 30% by mass of the entire spray particles are defined as the granular material B). FIG. 3A is an enlarged schematic diagram of the thermal spray coating formed by spraying the thermal spray particles, and FIG. 3B is an enlarged schematic diagram of the thermal spray coating formed by spraying only the granular cermet material A. Shown in Each sprayed coating shown in FIGS. 3A and 3B is formed on a base plating layer.
As shown in FIG. 3A, the material B exists at the grain boundary of the cermet material A by forming a sprayed coating with the sprayed particles obtained by mixing the granular cermet material A and the material B. For this reason, compared with the case where a sprayed coating is formed only by the cermet material A shown in FIG. 3 (B), the brittleness of the sprayed coating can be reduced and the toughness can be improved.

That is, when the amount of the material B in the spray particles is less than 5% by mass, the amount of the material B present at the grain boundary of the cermet material A is too small, and the effect of improving toughness cannot be obtained. On the other hand, when the amount of the material B in the sprayed particles exceeds 30% by mass, the amount of the cermet material A contained in the sprayed coating is too small, resulting in a decrease in the hardness of the sprayed coating and an increase in the volume wear rate. The material B is preferably present at all grain boundaries of the cermet material A, but may be partial.
From the above, the amount of the material B in the spray particles is 5% by mass or more and 30% by mass or less, but the lower limit is 8% by mass, further 10% by mass, the upper limit is 25% by mass, and further 20% by mass. It is preferable to do.

The cermet material A is Cr ₃ C ₂ : 10% by mass or more and 30% by mass or less (preferably the lower limit is 13% by mass, further 15% by mass, the upper limit is 27% by mass, further 25% by mass), Ni: 5 It is composed of 15% by mass or more and preferably 15% by mass (preferably the lower limit is 7% by mass, the upper limit is 12% by mass, and further 10% by mass), and the balance is WC. The cermet material A may contain, for example, Fe as an inevitable impurity.
By making the cermet material A as described above, the hardness is comparable to that of WC / 12% Co, which is generally used as a wear-resistant material, and the thermal shock resistance at high temperatures is 3 to 3. It can be improved about 5 times. Therefore, the crack resistance of the thermal spray coating 13 can be improved.

The thermal spray coating 13 shown above is formed by spraying thermal spray particles with a flame sprayer 14.
The flame sprayer 14 is a high-speed flame sprayer that makes the velocity of spray particles 600 m / second (preferably 700 m / second) or more, but a flame sprayer that is usually used can also be used. In addition, when a high-speed flame sprayer is used, the adhesive force of the thermal spray coating 13 to the base plating layer 12 can be further increased.
For the reasons described above, the upper limit of the velocity of the spray particles is not defined, but in reality, for example, it is about 1000 m / second.

Next, the manufacturing method of the casting mold for continuous casting which concerns on one embodiment of this invention is demonstrated.
First, as shown in FIGS. 1 and 2, a base plating layer 12 is formed by performing base plating having a thickness of about 100 μm on the inner surface of the molten steel contact surface side of the base material 11 constituting the continuous casting mold.
As an electrolytic solution in this case, a solution in which 350 g of S-Ni (nickel sulfamate), 5 g of nickel chloride, and 30 g of boric acid are dissolved in 1 liter is used. the density 3A / dm ^2. Here, the base plating layer is formed of Ni, but may be formed of, for example, Co or Fe, or may be formed of an alloy based on any one or more of Ni, Co, and Fe. Also good.

The underlying plating layer 12 is subjected to a roughening treatment, and the roughness of the surface of the underlying plating layer 12 is set to 50 μm or more and 150 μm or less.
Here, the roughening treatment is performed by a blast treatment using alumina. In addition, as an alumina to be used, for example, alumina having a grid size of # 24 can be used, and the air pressure at the time of blasting is set to about 0.49 MPa (5 kg / cm ² ).
Then, a granular cermet material A composed of Cr ₃ C ₂ , Ni, and the remainder WC and a granular material B composed of Ni or a Ni-based alloy are mixed on the ground plating layer 12 that has been roughened. The sprayed particles that are formed and have 5% by mass or more and 30% by mass or less of the entire material as the material B are sprayed by the flame sprayer 14.

Here, the particle size distribution of the cermet material A and the material B is, for example, about 5 μm or more and 60 μm or less (preferably the lower limit is 10 μm and the upper limit is 55 μm) considering the strength of the sprayed coating to be formed. Note that the particle size distributions of the cermet material A and the material B before thermal spraying may be the same or different.
The spray particles can be used by separately purchasing the cermet material A and the material B and mixing them in the above-mentioned proportions, but it is also possible to purchase and use those previously mixed.

As the flame sprayer 14 for spraying the sprayed particles, a high-speed flame sprayer that makes the speed of the sprayed particles 600 m / second (preferably 700 m / second) or more is used, but a conventionally known flame sprayer is used. You can also
As a result, as shown in FIG. 3A, the sprayed coating 13 in which the material B is present can be formed at the grain boundary of the cermet material A. The thickness of the thermal spray coating 13 is not particularly limited, but is preferably formed densely in the range of 0.1 mm to 1 mm.
The surface side of the sprayed coating 13 formed in this way is finished as necessary, and then used as a continuous casting mold.

Next, examples carried out for confirming the effects of the present invention will be described.
First, an underlying plating layer made of Ni was formed on the surface of a base material made of Cu—Cr—Zr by the method described in the above embodiment. Here, in the roughening treatment, an alumina grid having a particle size of # 24 was used, and the air pressure at that time was about 0.49 MPa.
Then, a sprayed coating having a thickness of about 0.8 mm was formed on the base plating layer using a high-speed flame spraying machine. Table 1 shows the types and ratios of materials constituting the thermal spray coating.

In addition, as shown in FIG. 4, the thermal shock resistance in Table 1 was evaluated by moving the plasma spraying machine at a constant speed to the surface side of the formed sprayed coating, and the number of times the crack was generated in the sprayed coating. In Table 1, the ratio of Comparative Examples 2 to 5 and Examples 1 to 4 was determined with the number of occurrences of cracks in Comparative Example 1 being 1.0.
The degree of extension of the mold life in Table 1 is the ratio of Comparative Examples 2 to 5 and Examples 1 to 4 by measuring the use time of the actually used mold and setting the time of Comparative Example 1 to 1.0. Asked.

As is apparent from Table 1, the thermal shock resistance of Examples 1 to 4 can be increased to 3 times or more (up to about 5 times) of the thermal shock resistance of Comparative Example 1, and Comparative Examples 1 to 4 can be increased. In comparison with Comparative Examples 4 and 5 having a high thermal shock resistance, the temperature could be increased twice or more. Therefore, it was confirmed that the mold life could be extended as compared with the prior art.
From the above, by using the continuous casting mold of the present invention and its manufacturing method, the toughness can be improved and the thermal shock resistance can be further improved. As a result, the life of the mold can be extended. It could be confirmed.

As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included. For example, a case where the continuous casting mold of the present invention and the manufacturing method thereof are configured by combining a part or all of the above-described embodiments and modifications is also included in the scope of the right of the present invention.
The cooling member for forming the thermal spray coating to which the present invention is applied includes a combination of four members composed of a pair of short sides and a pair of long sides, but is not limited to this. For example, a billet (For example, the width | variety and thickness are about 100-200 mm) or the tube shape thing which manufactures a bloom (for example, width | variety and thickness is about 200-400 mm) may be sufficient. Therefore, for the mold configuration, for example, a mold for producing a slab, billet, bloom, or beam blank (used for H-shaped steel), and further, a block mold in which water conduction holes are drilled in a forged or forged copper block, Of course, it is possible to apply the present invention.

10: Cooling member, 11: Base material, 12: Undercoat layer, 13: Thermal spray coating, 14: Flame sprayer

Claims (7)

In the continuous casting mold in which the base plating layer and the sprayed coating that have been roughened are sequentially formed on the molten steel contact surface side,
The thermal spray coating is composed of a granular cermet material A composed of Cr ₃ C ₂ : 10% by mass to 30% by mass, Ni: 5% by mass to 15% by mass, and the balance WC, and a granular cermet material composed of Ni or a Ni-based alloy. The material B is formed by mixing with the material B, and sprayed with 5 flame% or more and 30 weight% or less of the whole material B with a flame spraying machine, and the material B exists at the grain boundary of the cermet material A A casting mold for continuous casting, characterized by being formed. The mold for continuous casting according to claim 1, wherein the base plating layer is made of Ni, Co, Fe, or an alloy based on any one or more of these, and the surface of the base plating layer is: A continuous casting mold, wherein the roughness is 50 μm or more and 150 μm or less by the roughening treatment. The continuous casting mold according to claim 1 or 2, wherein the sprayed coating has a thickness of 0.1 mm or more and 1 mm or less. The continuous casting mold according to any one of claims 1 to 3, wherein the flame sprayer is a high-speed flame sprayer that sets the velocity of the spray particles to 600 m / sec or more. Mold. In the method for producing a casting mold for continuous casting, in which a base plating layer and a sprayed coating that have been roughened are sequentially formed on the molten steel contact surface side,
Mixing a granular cermet material A composed of Cr ₃ C ₂ : 10 mass% to 30 mass%, Ni: 5 mass% to 15 mass%, and the balance WC, and a granular material B composed of Ni or Ni-based alloy In addition, the thermal spray coating is formed by spraying thermal spray particles, which are 5% by mass or more and 30% by mass or less of the whole, with the material B using a flame spraying machine, and the material B is present at the grain boundaries of the cermet material A. A process for producing a casting mold for continuous casting, characterized in that 6. The method for manufacturing a continuous casting mold according to claim 5, wherein the base plating layer is made of Ni, Co, Fe, or an alloy based on any one or more of these, and the base plating layer is formed on the base plating layer. A method for producing a casting mold for continuous casting, wherein the thermal spray coating is formed after performing the surface roughening treatment so that the surface roughness is 50 μm or more and 150 μm or less. 7. The continuous casting mold according to claim 5, wherein a high-speed flame sprayer is used as the flame sprayer, and the velocity of the spray particles is 600 m / sec or more. Manufacturing method.

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