JP2005314721A - Water-cooling type steel-made tubular structure having excellent high-temperature corrosion resistance, high-temperature wear resistance, moisture condensation corrosion resistance, and film peeling resistance, and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-cooling type steel-made tubular structure constituting a converter exhaust gas cooling facility, etc., wherein a film having excellent high-temperature corrosion resistance, high-temperature wear resistance, moisture condensation corrosion resistance, and film peeling resistance is formed, a facility lifetime is long, the maintenance cost and the updating cost are reduced, and the rate of operation of the facility is enhanced, and to provide a method for manufacturing the same. <P>SOLUTION: The water-cooling type steel-made tubular structure is constituted so that Cr alloy of 22-60 mass% effective for high-temperature wear and high-temperature corrosion is covered on a surface of the water-cooling type steel-made tubular structure, and the heating and diffusion treatment is performed for improving the peeling resistance of a film and reducing pores, and a joining layer is formed and an oxidation preventive layer is formed depending on a heating condition so that a layer of Cr alloy of 22-60 mass% is not peeled, and the method for manufacturing the same is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a water-cooled steel pipe structure that is exposed to high temperature wear and high temperature corrosion due to high temperature exhaust gas and dust containing chlorine etc. that corrode steel, and depending on the situation, for example, steelmaking of steel plant In order to contribute to extending the life of converter exhaust gas cooling equipment in factories, etc., a steel substrate surface coating film with excellent high-temperature corrosion resistance, high-temperature wear resistance, dew condensation corrosion resistance, and film peeling resistance at an atmospheric temperature of 1000 K or higher. This is to provide a water-cooled steel structure and a manufacturing method therefor, and to contribute to the reduction of total life cycle cost by reducing the maintenance cost and stabilizing the operation by extending the life of the equipment. .

  In the case of converter exhaust gas treatment equipment, a water-cooled steel pipe made up of a skirt 2, hoods 3, 4, radiant section 5, duct 6, etc. in order to effectively recover the sensible heat of high-temperature exhaust gas and useful components contained in the exhaust gas. The structure is configured as shown in FIG.

  During use, these water-cooled steel pipe structures have high temperature corrosion due to high temperature exhaust gas containing components such as Cl that corrode steel and high heat generated during blowing from molten steel and various ores that are added as auxiliary materials. Subjected to significant erosion wear due to dust.

In addition, it is subject to corrosive gases such as Cl and S generated from iron scrap and auxiliary materials mixed with plastic, high temperature corrosion due to high temperature oxidation, and thermal stress fatigue due to repeated intermittent operation. Due to these erosion wear, high temperature corrosion and thermal stress fatigue, the steel pipe structure is damaged by wear and cracks such as fire cracks generated in the base material, and cooling water and water vapor flowing in the pipe of the pipe structure If it leaks, a steam explosion may occur due to the reaction between the hot molten steel and the leaked water, and a serious disaster may occur.
Therefore, it is necessary to periodically stop the equipment and perform maintenance, thereby reducing productivity.

  In order to solve these problems, in Patent Document 1, C: 0.03 to 0.3%, Si: 0.2 to 1.2%, Mn: 0.3 to 2.6%, Ni: 0.1 to 6.0%, Cr: 8.0 to 15.0%, A method has been proposed in which a material having a composition of Mo: 0.05 to 4.0%, V: 0.1 to 3.0%, and the balance Fe is sprayed on the surface of the cooling pipe.

Further, in Patent Document 2, a method of forming a coating excellent in heat resistance and erosion resistance by spraying a Cr ₃ C ₂ —Ni · Cr cermet on the surface of a cooling pipe and then spraying a MCrAlX alloy Has been proposed.

  In Patent Document 3, a base sprayed coating of a refractory metal or its alloy or carbide cermet is formed on the surface of a base material such as a pipe, and further a porous inorganic coating is interposed as required. After applying a sealant mainly composed of chromic acid and phosphoric acid, drying, heating and firing under conditions of 350 to 550 ° C. × 0.3 hr or more, 0.5 to 20 μm, preferably 2 to 5 μm thick hard glass A composite sprayed member formed by forming a chromium oxide film on the upper layer has been proposed.

Japanese Patent Publication No. 4-80089 Japanese Patent Laid-Open No. 7-018320 Japanese Patent No. 3039850

However, the above technique has the following problems to be solved. That is, for Patent Document 1, the adhesion mechanism between the base material and the sprayed coating is mainly a mechanical anchoring effect, and there is a problem in the bonding property of the sprayed particles and the adhesion to the base material. There are problems of high cost and insufficient erosion resistance due to the property.
Furthermore, in patent document 3, the restrictions of construction shape and lack of peeling resistance and wear resistance are pointed out as problems.

  Accordingly, an object of the present invention is to form a film excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and film peeling resistance, for example, to extend the life of converter exhaust gas cooling equipment, and to maintain maintenance costs and renewal costs. The object of the present invention is to provide a water-cooled steel pipe structure that achieves an improvement in the operating rate of the production facility.

The present invention for solving the above problems uses the following means.
(1) Bonding film containing 60 mass% or more of Ni on the surface of a steel base of a water-cooled steel pipe structure exposed to high temperature corrosion, high temperature wear and dew corrosion, 22 to 60 mass% of Cr, Ni It consists of a corrosion-resistant and abrasion-resistant coating coated with an alloy containing 35% by mass or more. A diffusion layer with a thickness of 1 μm or more is formed between the steel substrate surface and the coating, and the corrosion-resistant and abrasion-resistant coating. A water-cooled steel pipe structure excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and film peeling resistance, characterized by having a Vickers hardness of 300 to 700.
(2) Bonding film containing 60% by mass or more of Ni on the surface of the steel substrate of the water-cooled steel pipe structure exposed to high temperature corrosion, high temperature wear and dew condensation, 22 to 60% by mass of Cr and Ni It consists of an anti-corrosion / abrasion-resistant coating coated with an alloy containing 35% by mass or more and an anti-oxidation / anti-abrasion coating containing 50% by mass or more of Ni, with a thickness between the steel substrate surface and the coating. High-temperature corrosion resistance, high-temperature wear resistance, anti-condensation corrosion and film resistance, characterized in that a diffusion layer of 1 μm or more is formed and the hardness of the antioxidant and abrasion-resistant film is 300 to 700 in terms of Vickers hardness Water-cooled steel pipe structure with excellent peelability.

(3) Water-cooled steel excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and film peeling resistance, characterized in that the film thickness of the bonding film of (1) or (2) is 1 to 300 μm Pipe-making structure.
(4) Excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and delamination resistance, characterized in that the film thickness of the corrosion and abrasion resistant film of (1) or (2) is 100 to 1000 μm. Water-cooled steel pipe structure.
(5) High-temperature corrosion resistance and resistance, characterized in that the film thickness of the bonding film of (1) or (2) is 1 to 300 μm and the film thickness of the corrosion / abrasion resistant film is 100 to 1000 μm. A water-cooled steel pipe structure with excellent high-temperature wear, condensation corrosion resistance, and film peeling resistance.
(6) The water-cooled steel with excellent high temperature corrosion resistance, high temperature wear resistance, dew condensation resistance and anti-peeling resistance, characterized in that the film thickness of the anti-oxidation / anti-wear film of (2) is 100 to 500 μm. Pipe-making structure.
(7) The film thickness of the bonding film of (2) is 1 to 300 μm, the film thickness of the anticorrosion / abrasion resistant film is 100 to 1000 μm, and the film thickness of the antioxidation / abrasion resistant film is 100 A water-cooled steel pipe structure excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance, and film peeling resistance, characterized by having a thickness of ˜500 μm.

(8) After forming the bonding film and the corrosion / abrasion resistant film shown in (1) on the surface of the steel substrate of the water-cooled steel pipe structure exposed to the high temperature corrosion, high temperature wear and dew corrosion, the film region The surface of the steel substrate is subjected to a heat diffusion treatment that keeps it in the temperature range from the solidus temperature of the outermost coating to the liquidus temperature for at least 1 second in an atmosphere adjusted to an oxygen content of 1% by mass or less or reducing property. And a method for producing a water-cooled steel pipe structure excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and film peeling resistance, characterized by forming a diffusion layer of 1 μm or more between each film.
(9) Bonding film, corrosion resistance / abrasion resistance film and anti-oxidation / abrasion resistance film shown in (2) above on the surface of steel base of water-cooled steel pipe structure exposed to high temperature corrosion, high temperature wear and dew condensation corrosion After the film is formed, the film formation region is subjected to a heat diffusion treatment for holding for 1 second or more in the temperature range from the solidus temperature of the outermost film to the liquidus temperature in the air atmosphere, and between the surface of the steel substrate and each film A method for producing a water-cooled steel pipe structure excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and film peeling resistance, characterized in that a diffusion layer is formed in a thickness of 1 μm or more.
(10) The bonding film and the corrosion / abrasion resistant film shown in (1) above are formed on the surface of the steel base of the water-cooled steel pipe structure exposed to high temperature corrosion, high temperature wear and dew corrosion by welding. Manufacturing of water-cooled steel pipe structures with excellent resistance to high-temperature corrosion, high-temperature wear, condensation corrosion and anti-peeling, characterized by forming a diffusion layer of 1 μm or more between the steel substrate surface and each film Method.

The present invention, for example, by forming a film excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and film peeling resistance on a water-cooled steel pipe structure such as a converter exhaust gas cooling facility,
i) Abrasion resistance against ingots and dust generated during operation, and excellent corrosion resistance at sites exposed to high temperature corrosion.
ii) Thermal fatigue stress cracking is less likely to occur and is effective in preventing the occurrence of heat cracks.
iii) The protective film has excellent peeling resistance, and the protective effect can be sustained and maintained for a long time.
As a result, the service life of the equipment has been extended, the need for repairs with the equipment stopped is less than before, the operation rate of the equipment is improved, and the operation is stable. Can greatly contribute to the development.

  Hereinafter, the present invention will be described in detail. In the following description, “%” means “% by mass” unless otherwise specified.

  It is necessary to use an alloy containing 60% or more of Ni as a bonding film (first layer) on the surface of the water-cooled steel pipe structure. This is to increase the bonding strength by using an alloy containing Ni having high affinity for Fe of the steel substrate and Cr of the second-layer corrosion-resistant and wear-resistant film described later.

  In consideration of the strength and corrosion resistance of the bonding film to be formed, the components other than Ni are preferably 1 to 5% for B, 1 to 5% for Si, 0 to 15% for Cr, and more than 0 to 5 for Fe. %, Cu is more than 0 to 4%, Mo is more than 0 to 4%, W is more than 0 to 2%, C is more than 0 to 1.1%, and the balance is unavoidable. An alloy made of The reason for this is that for B and Si, at least 1% or more is required in order to lower the melting point of the bonding film, to lower the solidus temperature to about 1373K or lower, and to lower the liquidus temperature to about 1473K or lower. However, if the content exceeds 5%, the heat diffusion treatment described below forms boride and silicide, and the toughness of the Ni alloy solid solution of the base is reduced, thereby inhibiting the heat fatigue resistance of the bonding film. Must be 5% or less.

  From the viewpoint of corrosion resistance and film strength, Cr can be contained up to 20%, Fe up to 5%, Cu up to 4%, Mo up to 4%, W up to 2% and C up to 1.1%. However, if it is contained more than each, the toughness of the film is lowered, and there is a drawback that cracks are easily generated in the film during operation.

  It is desirable to form the above-mentioned bonding film with a thickness of 1 to 300 μm. The reason for this is that a minimum film thickness of 1 μm or more is required to form a diffusion layer of 1 μm or more. On the other hand, if the thickness exceeds 300 μm, the effect is saturated and economically unsuitable. As a method for forming the bonding film, a spraying method, a plating method, and a welding method can be applied, but the spraying method is particularly preferable.

  Next, from the viewpoint of corrosion resistance against corrosion sources containing Cl and S as a corrosion / abrasion resistant film (second layer) formed on the upper layer after the formation of the bonding film, it contains 22 to 60% of Cr. And from the viewpoint of the toughness of the formed film and the high temperature oxidation resistance, it is necessary to be an alloy containing Ni of 35% or more. The reason is based on the following hot corrosion resistance test results.

For high-temperature corrosion resistance evaluated by Cr and Ni components, corrosion ash with a coating material from four different contents of Cr and Ni (SFNi4, Ni-alloy, Cr 3 C 2, Inconel625, and the present invention material) Immersion test method (for example, Yoshio Harada; Material 31, no. 349, 54 (1982): A test piece was immersed in 1% chlorine dust-collected dust placed in an alumina crucible and sealed at 400 ° C. for 300 hours- The erosion situation was tested by heating in an electric furnace with a compression force of 4 MPa. The results are shown in Table 1.

In SFNi4, Ni-alloy and Inconel 625 with Cr of less than 22%, the film is melted and the ratio of the damage exceeds 10%, the corrosion resistance under the corrosive conditions is low, and Cr ₃ C _{2 with} Ni of less than 35%. Then, the film was cracked and damaged.
On the other hand, the melting loss ratio of the high temperature corrosion resistant coating of the present invention was 1/10 to 1/30, which was very good.

  In addition, even if Cr is added in excess of 60%, the melting loss ratio is not improved and the effect is saturated. Therefore, the upper limit of the Cr addition amount is set to 60% from the economical viewpoint.

  Preferably, Cr is 40-60%, Ni is 35% or more, B is 0.5-5%, Si is 0.5-5%, Mo is 0.1-3%, and one or more are contained, and the balance is inevitable. It is desirable that the alloy be composed of mechanical impurities.

  B and Si are required to be 0.5% or more in order to lower the melting point of the corrosion-resistant and abrasion-resistant film, to bring the solidus temperature to about 1373K or lower, and to further bring the liquidus temperature to about 1673K or lower. However, if it contains more than 5%, the heat diffusion treatment described below forms boride and silicide with the contained components, and also lowers the toughness of the Ni alloy solid solution of the base, inhibiting the heat fatigue resistance of the corrosion and wear resistant coatings. , There is a drawback that cracks are likely to occur in the film during operation.

  If the Mo content is less than 0.1%, the high-temperature strength of the film decreases, and if it exceeds 3%, the oxidation resistance of the film decreases.

  When the outermost layer is a corrosion / abrasion resistant film, the film hardness needs to be 300 to 700 Vickers hardness. This is because the average hardness of the wear particles (dust) is about 300 in terms of Vickers hardness, so if the film surface hardness is less than 300, the wear resistance is poor, and if the film hardness exceeds 700, the film will crack. This is because it becomes easy to occur.

  Further, it is desirable that the corrosion-resistant and abrasion-resistant film is formed to a thickness of 100 to 1000 μm. The reason for this is that when the thickness is less than 100 μm, the period of time when the corrosion-resistant / abrasion-resistant film is damaged quickly and the performance is insufficient may be insufficient, and when it exceeds 1000 μm, the effect is saturated and economically unsuitable.

  Furthermore, sufficient effects can be obtained only with the above-mentioned bonding film formed on the upper part of the base material, corrosion resistance and abrasion resistance skin, but in order to further improve the wear resistance together with the oxidation prevention of these films, It is further desirable to form an alloy film containing 50% or more of Ni as the wear-resistant film (third layer).

  The reason for applying an alloy containing Ni as an anti-oxidation / anti-wear film (third layer) is that Ni has a high affinity with Cr contained in the anti-corrosion / anti-wear film (second layer). This is because when Ni is 50% or more, a great effect can be obtained on the antioxidant and wear resistance. As components other than Ni, B is preferably 1 to 5%, Si is 1 to 5%, and Cr is 10 to 20 in consideration of the anti-oxidation and melting point and wear resistance of the abrasion-resistant film to be formed. %, Fe over 0-5%, Cu over 0-4%, Mo over 0-4%, C 0.05-1.1%, and the balance is inevitable impurities. An alloy made of The reason for this is that B and Si are 1% in order to lower the melting point of the antioxidant and anti-wear coating, to lower the solidus temperature to about 1373K or lower, and to lower the liquidus temperature to about 1473K or lower. This is necessary. However, if it contains more than 5%, it will form boride and silicide with the components and heat diffusion treatment described later, and also lower the toughness of the Ni alloy solid solution of the base, preventing oxidation and the thermal fatigue resistance of the wear-resistant coating Therefore, it is necessary to make it 5% or less.

  Also, from the viewpoints of wear resistance and corrosion resistance, Cr should be 10-20%, Fe 5%, Cu 4%, Mo 4%, W 2% and C 0.05-1.1%. However, if it is contained in more than the respective ranges, the toughness of the film is reduced, and if it is less than the respective ranges of Cr and C, the wear resistance and corrosion resistance are reduced, and the film is cracked during operation. There is a drawback that it tends to occur.

  In addition, when forming an anti-oxidation / anti-abrasion film, it is necessary to use an alloy having a Vickers hardness of 300 to 700 which constitutes the anti-oxidation / anti-abrasion film. The reason for this is that the average hardness of the wear particles (dust) is about 300 in terms of Vickers hardness, as described above, so if the film surface hardness is less than 300, the wear resistance is inferior and the film hardness exceeds 700. This is because cracks are likely to occur in the film.

  Furthermore, it is also preferable that the antioxidant / antiwear coating is formed to a thickness of 100 to 500 μm. The reason for this is that when the thickness is less than 100 μm, the period during which the wear resistance film is damaged quickly and the performance is insufficient may be insufficient, and when it exceeds 500 μm, the effect is saturated and economically unsuitable.

Next, a method for producing a water-cooled steel pipe structure will be described below.
In the aggregate of pipes, a region where the film of the present invention is formed inside the furnace of a facility in which a circular water-cooled steel pipe structure is configured as shown in FIG. It is preferable to remove scale, dirt, etc. on the surface of the surface. This is because it is possible to form a rough surface that does not peel off the heat-treated film after the film formation of the present invention described later.

  As a method for forming the rough surface, a mechanical method such as keren and a chemical method such as pickling can be applied in addition to the blast treatment. The film forming method is not particularly limited, and among the spraying methods, a plasma spraying method, a high-speed flame spraying method, a gas flame spraying method, or a welding method can be used.

  In the case of a two-layer coating with a bonding coating and corrosion / abrasion-resistant coating on the surface of the steel material, the surface of the formed coating and the surface of the steel substrate are adjusted to an oxygen content of 1% or less or reduced. It is necessary to carry out a heat diffusion treatment that maintains the temperature range between the solidus temperature and the liquidus temperature of the corrosion-resistant and abrasion-resistant film, which is a film, for 1 second or more. For example, in the case of an alloy consisting of Cr: 40-60%, Ni: 35% or more, B: 1.5-5%, Si: 1.5-5%, Mo: 0.1-3%, and the balance of inevitable impurities, a solid phase Since the line temperature is about 1223K and the liquidus temperature is about 1623K, a heat diffusion process is performed in which the temperature is kept in this range for 1 second or longer.

  By this heat diffusion treatment, diffusion between the film-forming particles and formation of a diffusion layer between the steel substrate and the bonding film are achieved, and a diffusion layer is also formed at the interface between the corrosion-resistant and abrasion-resistant film and the bonding film. As a result, the shear strength between the film and the steel base material, which was about 30 MPa before the heat diffusion treatment, reaches 100 MPa or more after the heat diffusion treatment, and the peel resistance of the film is remarkably improved. Furthermore, when Cr, B, and C are contained in the film component, hard components such as Cr boride and Cr carbide precipitate. This makes it possible to make the film hardness 300 to 700 in terms of Vickers hardness and improve the wear resistance.

  Similarly, among these coatings, in the case of a three-layer coating with a bonding coating, a corrosion / abrasion resistant coating, and an antioxidant and an abrasion resistant coating on the surface of the steel material, the formed coating and the vicinity of the steel substrate surface are exposed to the atmosphere. In the atmosphere, it is necessary to carry out a heat diffusion treatment for holding for 1 second or more in the temperature range from the solidus temperature to the liquidus temperature of the antioxidant and anti-wear coating which is the outermost film. For example, in the case of an alloy containing Ni of 50% or more, Cr: 10.38%, Si: 2.91%, Fe: 2.20%, B: 1.55%, C: 0.39% and the balance consisting of inevitable impurities, Since the temperature is about 1223K and the liquidus temperature is about 1373K, a heat diffusion process is performed in which the temperature is kept in this range for 1 second or longer.

  By this heat diffusion treatment, the outermost layer is heated and a liquid phase is formed on the outermost layer, so that the outermost layer film plays a role of preventing oxidation of the lower layer film. Furthermore, this heat diffusion treatment achieves diffusion between the film-forming particles and the formation of a diffusion layer between the steel substrate and the bonding film, at the respective interfaces of the anti-oxidation and anti-abrasion film and the anti-corrosion / anti-abrasion film and the bonding film. Also, a diffusion layer can be formed. Before this heat diffusion treatment, the shear strength between the film and the steel substrate, which was about 30 MPa, reaches 100 MPa or more after the heat diffusion treatment, and the peel resistance of the film is significantly improved. Furthermore, when Cr, B, and C are contained in the film component, hard components such as Cr boride and Cr carbide precipitate. This makes it possible to make the film hardness 300 to 700 in terms of Vickers hardness and improve the wear resistance.

  Note that if the heat diffusion treatment temperature is lower than the solidus temperature of the material, the above reaction becomes a solid diffusion reaction, and a long time treatment is required before exhibiting a predetermined performance. Lack of reliability of adhesion to the material. Further, if the liquidus temperature is exceeded, there is a problem that the material is fluidized and flows out from the surface of the structure to form a uniform film. Accordingly, the heat diffusion treatment temperature is in the range between the solidus temperature and the liquidus temperature. Also, as the retention time within the solidus temperature and liquidus temperature range, the diffusion layer cannot be formed more than 1 μm in a short time of less than 1 second, and the predetermined film performance cannot be exhibited. Is 1 second or longer.

  When all the films are formed by the welding method, the heat diffusion treatment may be omitted. This is due to the formation of a diffusion layer during welding.

  As a heating method in the heat diffusion treatment, there are a method using a gas burner, a method of heating in a gas furnace or an electric furnace having an oxygen concentration of 1% or less, or a reducing atmosphere, but if there is a size and shape limitation, a gas torch Use the law. In order to prevent or minimize deformation (strain) generated in the structure during heating, it is preferable to use an appropriate restraining jig.

  The water-cooled steel pipe structure preferably forms a high temperature corrosion resistant, high temperature wear resistant film according to the present invention before the entire assembly is completed, and is generally a component composed of 3 to 15 tubes. In this state, a film excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and film peeling resistance according to the present invention is formed.

  Even in the formation of high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance, and excellent film peeling resistance film according to the present invention after complete assembly, heat diffusion treatment is performed by using an appropriate deformation prevention restraint tool and gas burner heating. However, since it is in the air atmosphere, it is desirable to form a three-layer film in which a bonding film, a corrosion / abrasion resistant film, and an antioxidant and an abrasion resistant film are formed on the surface of the steel substrate.

  Hereinafter, comparative examples and examples of the present invention will be described.

(1) Invention Example 1
In the embodiment of the present invention, in the lower hood of the converter exhaust gas facility which is a water-cooled steel pipe structure exposed to high temperature corrosion, high temperature wear and dew condensation corrosion, the fin having the shape shown in FIG. 3 in the region 8 shown in FIG. The surface of 10 steel substrate contains 60% or more of Ni, the balance being 10.38% Cr, 2.91% Si, 2.20% Fe, 1.55% B, 0.02% C, and a bonding film 11 consisting of unavoidable impurities of 1-100 μm A film is formed with a film thickness, and the surface is composed of 49.0% Cr, 48.0% Ni, 1% B, 1% Si, 1% Mo and inevitable impurities as a corrosion- and abrasion-resistant film 12, and the solidus temperature is 1363K. After forming a film with a thickness of 100 to 400 μm, a heat diffusion treatment is performed by holding the film formation region at a temperature of 1373 to 1623 K in an atmosphere adjusted to a reducing property for 10 seconds. 10 μm diffusion layer is formed on the interface, each film interface and each film, and the film hardness is Resistance to hot corrosion in Vickers hardness 300-500, high temperature wear, to form a film excellent in resistance to condensation corrosion and 耐皮 film peelability, was used at 1 year actual furnace.

  During this time, in the film formation region with excellent resistance to high temperature corrosion, high temperature wear, condensation corrosion, and film peeling, film peeling, substrate exposure due to wear, substrate exposure due to corrosion, thermal fatigue stress corrosion cracking There was no problem that caused troubles in operation such as water leakage.

(2) Invention Example 2
In the embodiment of the present invention, 60% or more of Ni is contained in the same region as in the first embodiment, and the balance is 10.38% Cr, 2.91% Si, 2.20% Fe, 1.55% B, 0.02% C and an inevitable impurity. The film 11 is formed with a film thickness of 100 to 200 μm, and the surface thereof is composed of 53.9% Cr, 42.0% Ni, 2.53% Mo, 0.98% Si, 0.53% B and inevitable impurities as a corrosion-resistant and wear-resistant film 12. After forming an alloy film with a thickness of 400 to 800 μm, the outermost layer contains 50% or more of Ni as an anti-oxidation and anti-wear coating 13 with the balance being 10.38% Cr, 2.91% Si, 2.20% Fe, 1.55% B After forming a film of an alloy consisting of 0.39% C and inevitable impurities and having a solidus temperature of 1263 K with a film thickness of 200 to 400 μm, the film forming region is kept at a temperature of 1273 to 1423 K for 20 seconds in an air atmosphere. Heat diffusion treatment is performed, and the interface with the steel substrate, each film interface, and inside each film Forms a diffusion layer of 20 μm, and forms a coating with excellent surface temperature resistance of 400 to 600, high-temperature corrosion resistance, high-temperature wear resistance, dew condensation corrosion resistance, and resistance to film peeling. used.

  During this time, in the film formation region with excellent resistance to high temperature corrosion, high temperature wear resistance, dew condensation corrosion, and film peeling resistance, film peeling, substrate exposure due to wear, substrate exposure due to corrosion, thermal fatigue stress corrosion cracking There was no problem that caused troubles in operation such as water leakage.

(3) Invention Example 3
In the embodiment of the present invention, 60% or more of Ni is contained in the same region as in the embodiment 1, with the balance being 16.33% Cr, 4.35% Si, 2.82% Fe, 2.65% B, 2.09% Mo, 1.99% Cu, 0.72%. Bonding film 11 composed of C and inevitable impurities is formed to a film thickness of 200 to 300 μm, and the surface thereof is corrosion- and abrasion-resistant film 12 as 56.5% Cr, 39.0% Ni, 2.53% Mo, 0.98% Si, 0.53 After forming a film of 800% to 1000 μm in thickness of an alloy consisting of% B and inevitable impurities, the outermost layer contains 50% or more of Ni as an anti-oxidation and anti-wear film 13 with the balance being 16.33% Cr, 4.35% Si , 2.82% Fe, 2.65% B, 2.09% Mo, 1.99% Cu, 0.72% C and an inevitable impurity, and an alloy with a solidus temperature of 1223K is formed with a film thickness of 400-500μm, then the film is formed Heat diffusion treatment is performed to keep the region at a temperature of 1373-1623K in air for 100 seconds. Diffusion layer is formed 100 μm at the interface with steel substrate, each film interface and each film, and the surface hardness of the film is 500 to 700 with high Vickers hardness, high temperature corrosion resistance, high temperature wear resistance, condensation corrosion resistance and resistance to film peeling A film with excellent properties was formed and used in an actual furnace for one year.

  During this time, in the film formation region with excellent resistance to high temperature corrosion, high temperature wear, condensation corrosion, and film peeling, film peeling, substrate exposure due to wear, substrate exposure due to corrosion, thermal fatigue stress corrosion cracking There was no problem that caused troubles in operation such as water leakage.

(4) Comparative Example 1
High temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance, and water-cooled steel base material STB340 of the lower hood that does not form a film with excellent resistance to film peeling will reduce the tube thickness by up to about 3 mm after about 12 months of use. Therefore, measures such as repairing the surface of the steel base by the overlay welding method have been implemented.

It is a schematic diagram which shows a converter exhaust gas cooling equipment. It is sectional drawing of the lower hood which is the water-cooling type steel pipe structure excellent in the high temperature corrosion resistance, high temperature abrasion resistance, dew condensation corrosion resistance, and film peeling resistance which concerns on this invention. Cross-sectional view and membrane layer of membrane by center fin type circular pipe constituting lower hood which is water-cooled steel pipe structure excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and film peeling resistance according to the present invention It is a block diagram.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Converter 2 ... Skirt 3 ... Lower hood 4 ... Upper hood 5 ... Radiation part 6 ... Dust collector duct 7 ... Lower hood cross section 8 ... High temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and delamination resistance according to the present invention Film formation region 9 excellent in water-cooled steel pipe 10 ... fin 11 ... bonding film 12 ... corrosion and abrasion resistant film 13 ... antioxidation and abrasion resistant film

Claims (10)

  Bonded film containing 60 mass% or more of Ni on the surface of the steel base of a water-cooled steel pipe structure exposed to high temperature corrosion, high temperature wear and condensation corrosion, 22 to 60 mass% of Cr, and 35 mass% of Ni It consists of corrosion-resistant and abrasion-resistant coatings coated with the respective alloys described above. A diffusion layer with a thickness of 1 μm or more is formed between the steel substrate surface and the coating, and the hardness of the corrosion-resistant and abrasion-resistant coatings. Is a water-cooled steel pipe structure excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance, and film peeling resistance, characterized by having a Vickers hardness of 300 to 700.   Bonded film containing 60 mass% or more of Ni on the surface of the steel base of a water-cooled steel pipe structure exposed to high temperature corrosion, high temperature wear and condensation corrosion, 22 to 60 mass% of Cr, and 35 mass% of Ni It consists of an anti-corrosion / abrasion-resistant film coated with an alloy containing each of the above and an anti-oxidation / abrasion-resistant film containing Ni in an amount of 50% by mass or more. High temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance, and delamination resistance are characterized by forming a diffusion layer and having an anti-oxidation and abrasion-resistant film hardness of 300 to 700 in terms of Vickers hardness. Excellent water-cooled steel pipe structure.   3. A water-cooled steel pipe structure excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and film peeling resistance, characterized in that the film thickness of the bonding film according to claim 1 or 2 is 1 to 300 μm.   A water-cooled steel pipe excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and film peeling resistance, characterized in that the film thickness of the corrosion resistant and abrasion resistant film according to claim 1 or 2 is 100 to 1000 µm. Structure.   3. The high temperature corrosion resistance, high temperature wear resistance, and dew condensation resistance characterized in that the film thickness of the bonding film according to claim 1 or 2 is 1 to 300 [mu] m and the film thickness of the corrosion resistant and abrasion resistant film is 100 to 1000 [mu] m. And a water-cooled steel pipe structure with excellent film peel resistance.   A water-cooled steel pipe structure excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and film peeling resistance, characterized in that the film thickness of the antioxidant / antiwear film according to claim 2 is 100 to 500 μm. .   The film thickness of the bonding film according to claim 2 is 1 to 300 μm, the film thickness of the corrosion / abrasion resistant film is 100 to 1000 μm, and the film thickness of the antioxidant / abrasion resistant film is 100 to 500 μm. A water-cooled steel pipe structure excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance, and film peeling resistance.   After the bonding film and the corrosion / abrasion resistant film shown in claim 1 are formed on the surface of the steel substrate of the water-cooled steel pipe structure exposed to high temperature corrosion, high temperature wear and dew condensation corrosion, the amount of oxygen is reduced to 1 Perform a heat diffusion treatment that maintains the temperature range from the solidus temperature of the outermost film to the liquidus temperature for 1 second or more in an atmosphere adjusted to less than mass% or reducing, and between the steel substrate surface and each film A method for producing a water-cooled steel pipe structure excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and film peeling resistance, characterized in that a diffusion layer is formed in a thickness of 1 μm or more.   After forming the bonding film, corrosion resistance / abrasion resistance film and anti-oxidation / abrasion resistance film shown in claim 2 on the surface of the steel substrate of the water-cooled steel pipe structure exposed to high temperature corrosion, high temperature wear and dew condensation corrosion, A diffusion layer is formed between the surface of the steel substrate and each film by performing a heat diffusion treatment in which the film formation region is maintained in the temperature range from the solidus temperature of the outermost film to the liquidus temperature for 1 second or more in an air atmosphere. A method for producing a water-cooled steel pipe structure excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and film peeling resistance, characterized by being formed at 1 μm or more.   The joining film and the corrosion / abrasion resistant film shown in claim 1 are formed on the surface of the steel substrate of the water-cooled steel pipe structure exposed to high temperature corrosion, high temperature wear and dew condensation corrosion by a welding method. A method for producing a water-cooled steel pipe structure excellent in high temperature corrosion resistance, high temperature wear resistance, dew condensation corrosion resistance and film peeling resistance, characterized by forming a diffusion layer of 1 μm or more between the surface and each film.

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