A nickel-based high-temperature alloy prefabricated part for repairing high-temperature components of a gas turbine and a preparation method thereof

Abstract

The present invention provides a nickel-based high-temperature alloy preform for repairing high-temperature components of gas turbines and a preparation method thereof, the purpose of which is to develop a high-density, non-segregated nickel-based high-temperature alloy powder metallurgy repair preform technology suitable for high γ' strengthening phase, which can make the joint structure of the repaired preform dense and have excellent high-temperature creep resistance and tensile strength. The nickel-based high-temperature alloy preform is mainly prepared from low-melting point alloy powder, high-melting point alloy powder and binder. The preform is fixed to the damaged area of ​​the high-temperature component of the gas turbine after the coating is removed by spot welding, and repaired by specific heat treatment. The interface of the repaired area is firmly connected, the joint structure is uniform, the carbide or boride is distributed in a granular form, the mechanical strength of the joint can reach more than 80% of the strength of the new high-temperature component of the gas turbine, and the porosity of the repaired joint is ≤1%.

Description

Technical Field

[0001] The invention relates to a high-temperature alloy preform and a preparation method thereof, and in particular to a nickel-based high-temperature alloy preform for repairing high-temperature components of a gas turbine and a preparation method thereof. Background Art

[0002] With the gradual improvement of gas turbine efficiency, the requirements for the mechanical properties of high-temperature alloys in the turbine area are also gradually increasing. In order to meet the application requirements, high-temperature alloy structures with high γ' strengthening phases, that is, nickel-based high-temperature alloys with high Al+Ti content, are usually selected. However, this series of nickel-based high-temperature alloys with high Al+Ti content are subjected to service damage. The weldability of high-temperature alloys with high γ' strengthening phases is poor when melt welding is used. When repairing large defects, it will cause large deformation and failure cracks. In addition, the brazing method is not effective for repairing larger defect sizes. For this reason, people are committed to large gap defect repair technology. At present, powder metallurgy is mainly used to repair large defects. However, for the repair of large defects, traditional powder metallurgy repair is prone to component segregation, resulting in uneven microstructure. As the defect size increases, the probability of repairing defects (holes) also increases accordingly, and the quality of repair of service parts is difficult to quantify and control. Summary of the invention

[0003] The present invention provides a nickel-based high-temperature alloy preform for repairing high-temperature components of a gas turbine and a preparation method thereof. The purpose is to provide a high-density, non-segregated nickel-based high-temperature alloy powder metallurgy repair preform technology suitable for high γ' strengthening phase in order to address the current technical problems in this field. The repaired preform can make the joint structure of the connected joint dense and have excellent high-temperature creep resistance and tensile strength.

[0004] The present invention is achieved through the following technical solutions:

[0005] A nickel-based high-temperature alloy preform for repairing high-temperature components of a gas turbine is sintered from nickel-based high-temperature alloy repair powder, wherein the nickel-based high-temperature alloy repair powder comprises high-melting point alloy powder, low-melting point alloy powder and a binder.

[0006] The high melting point alloy powder and the low melting point alloy powder are mixed into nickel-based high temperature alloy powder; in terms of weight percentage, the nickel-based high temperature alloy powder includes 50% to 70% of high melting point alloy powder and 30% to 50% of low melting point alloy powder.

[0007] The nickel-based high-temperature alloy powder and the binder are mixed to form the nickel-based high-temperature alloy repair powder; in terms of weight percentage, the nickel-based high-temperature alloy repair powder includes 85% to 95% of the nickel-based high-temperature alloy powder and 5% to 15% of the binder.

[0008] The low melting point alloy powder contains, by weight percentage, 14.00% to 20.00% Cr, 0.20% to 1.50% W, 0.50% to 2.00% Mo, 8.00% to 10.00% Co, 2.50% to 5.50% Ta, 3.00% to 4.00% Al, 0.00% to 2.00% Ti, 1.00% to 2.50% Nb, 0. 10% to 0.35% Zr, 0.05% to 0.2% Hf, 0.001% to 0.01% Y, 0.005% to 0.01% Ce, 0.001% to 0.01% La, 0.001% to 0.006% Mg, 2.3% to 2.7% B, the remainder being Ni and unavoidable impurity elements; the purity of each component raw material of the low melting point alloy powder is not less than 99.99%.

[0009] The high melting point alloy powder has the same material composition as the gas turbine turbine high temperature component to be repaired; the high melting point alloy powder is preferably a nickel-based high temperature alloy with high γ' strengthening phase such as Mar M247, In738 or GTD-222.

[0010] The low melting point alloy powder is a multi-component complex alloy powder with good melting point suppression and strengthening effects.

[0011] The particle size of the above-mentioned low melting point alloy powder and high melting point alloy powder is -53μm.

[0012] The melting temperature of the low melting point alloy powder is 1050°C to 1140°C.

[0013] A method for preparing a nickel-based high-temperature alloy prefabricated part for repairing a high-temperature component of a gas turbine, the specific method comprising:

[0014] (1) Select Mar M247, In 738 or GTD-222 nickel-based high-temperature alloy, and use a rotating electrode method to prepare and screen the required high-melting-point alloy powder;

[0015] (2) Ni, Cr, W, Mo, Co, Ta, Al, Ti, Nb, Zr, Hf, Y, Ce, La, Mg, and B are mixed, and then the above raw materials are melted into alloy ingots by vacuum induction melting, and then the desired low melting point alloy powder is prepared and screened by plasma atomization;

[0016] (3) mixing the processed high melting point alloy powder and low melting point alloy powder, adding a binder, and then mechanically mixing them uniformly to obtain a nickel-based high temperature alloy repair powder;

[0017] (4) Place the nickel-based high-temperature alloy repair powder in a mold and sinter it in a vacuum hot pressing furnace to prepare a preform. The vacuum degree in the vacuum hot pressing furnace is less than 1×10 -3Pa, the sintering temperature is 50℃~100℃ lower than the melting point of the alloy ingot, and the pressure in the vacuum hot pressing furnace is 0~35MPa;

[0018] (5) After sintering, the mold around the prefabricated part is removed, and the prefabricated part is processed by mechanical grinding, wire cutting, laser cutting or water cutting to meet the needs of repairing gas turbine service parts.

[0019] Among them, the sintering conditions in the vacuum hot pressing furnace are preferably: increasing the temperature to 900℃±10℃ at a speed of ≤10℃ / min and keeping it for 20-30min, increasing the temperature to 1000℃±10℃ at a speed of ≤8℃ / min and keeping it for 10-20min, applying a pressure of 5-20MPa, increasing the temperature to 1040℃±10℃ at a speed of ≤3℃ / min and keeping it for 5-15min, applying a pressure of 20-35MPa, and after the insulation is completed, reducing the temperature to 400℃ at a speed of ≥20℃ / min and cooling to room temperature with the furnace.

[0020] The prepared preform has a thickness of 1 mm to 5 mm, a length and a width determined by a mold, a dense internal structure, and a porosity of ≤3%.

[0021] The nickel-based high-temperature alloy is preferably a nickel-based high-temperature alloy product of Maritime House Co. Ltd or Western Australian Specialty Alloys Pty Ltd.

[0022] The above-mentioned adhesive is a commercial product, preferably NICROBRAZ-S adhesive from Wall Colmonoy Corporation.

[0023] Specific applications of the nickel-based high-temperature alloy preform for repairing high-temperature components of gas turbines prepared by the present invention:

[0024] 1. Use mechanical sandblasting to remove the coating on the gas turbine service parts.

[0025] 2. Use mechanical grinding to grind defects and some microcracks on gas turbine service parts to form repair pits or grooves, and use alcohol or acetone to clean the repair pits and grooves.

[0026] 3. Fix the nickel-based high-temperature alloy prefabricated parts to the surface of the repair area of ​​the gas turbine turbine service component by spot welding, and place the gas turbine turbine service component in a vacuum heat treatment furnace for heat treatment; the heat treatment furnace is raised to 1000°C at a speed of ≤15°C / min, and the heat treatment furnace is kept at 1000°C for 30 minutes, the heat treatment furnace is raised to 1190°C at a speed of ≤8°C / min, and the heat treatment furnace is kept at 1190°C for 30 minutes, and the heat treatment furnace is reduced to 500°C at a speed of ≥10°C / min, and the heat treatment furnace is cooled to room temperature after 500°C.

[0027] 4. Grind the heat-treated gas turbine repair component according to the original component shape, and then perform a restorative heat treatment on the overall gas turbine repair component structure. Finally, re-prepare the coating on the gas turbine repair component.

[0028] The nickel-based high-temperature alloy preform for repairing high-temperature components of gas turbines provided by the present invention is suitable for repairing nickel-based high-temperature alloy substrates with high Al+Ti content and high γ' strengthening phase, as well as defects with large depth (≥1.0mm).

[0029] Beneficial effects of the present invention:

[0030] 1. A prefabricated part of a specific size is used according to the damaged size of the high-temperature component of the gas turbine or the size of the damage artificially processed to a specific size. The prefabricated part is fixed to the damaged area of ​​the high-temperature component of the gas turbine after the coating is removed by spot welding, and repaired by a specific heat treatment. The interface of the repaired area is firmly connected, the joint structure is uniform, the carbide or boride is distributed in a granular form, and the mechanical strength of the joint can reach more than 80% of the strength of the new high-temperature component of the gas turbine.

[0031] 2. The porosity of the joint after repair is ≤1%.

[0032] 3. A nickel-based high-temperature alloy preform for repairing high-temperature components of gas turbines is used to repair large-size defects of nickel-based high-temperature components with high Al+Ti content. The repair process is simple to operate, and high-temperature components can be repaired simultaneously in batches, greatly improving the efficiency of high-temperature component repair and reducing manufacturing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the metallographic image of the gas turbine turbine service component after partial repair according to the present invention. DETAILED DESCRIPTION

[0034] The nickel-based high-temperature alloy preform for repairing high-temperature components of a gas turbine of the present invention will be described in detail below in conjunction with specific embodiments.

[0035] Example 1

[0036] Table 1 shows three groups of proportions of low melting point alloy powders in Examples 2-4 of the nickel-based high temperature alloy preforms for repairing high temperature components of gas turbine turbines of the present invention.

[0037] Table 1

[0038]

[0039] Example 2

[0040] A preparation method and a repair method of a nickel-based high-temperature alloy prefabricated part for repairing a high-temperature component of a gas turbine, the specific steps are:

[0041] (1) Selecting Mar M247 nickel-based high-temperature alloy, and using a rotating electrode method to prepare and screen the required high-melting-point alloy powder;

[0042] (2) Ni, Cr, W, Mo, Co, Ta, Al, Ti, Nb, Zr, Hf, Y, Ce, La, Mg, and B with a purity of not less than 99.99% are prepared according to the ratio provided in sequence number 1 in Example 1, and then the raw materials are melted into alloy ingots by vacuum induction melting, and then the desired low melting point alloy powder is prepared and sieved by plasma atomization;

[0043] (3) After the processed high melting point alloy powder and low melting point alloy powder are mixed, a binder is added, and then the mixture is mechanically and uniformly mixed to obtain a nickel-based high temperature alloy repair powder; the binder is NICROBRAZ-S binder produced by Wall Colmonoy Corporation; by weight percentage, the high melting point alloy powder accounts for 50% and the low melting point alloy powder accounts for 50% of the nickel-based high temperature alloy powder; the nickel-based high temperature alloy powder and the binder are uniformly mixed to obtain a nickel-based high temperature alloy repair powder, by weight percentage, the binder accounts for 15% and the nickel-based high temperature alloy powder accounts for 85%.

[0044] (4) Place the nickel-based high-temperature alloy repair powder in a mold and sinter it in a vacuum hot pressing furnace to prepare a preform. The vacuum degree in the vacuum hot pressing furnace is less than 1×10 -3 Pa, in a vacuum hot pressing furnace, the temperature is raised to 900℃±10℃ at a speed of ≤10℃ / min and kept for 20-30min, then raised to 1000℃±10℃ at a speed of ≤8℃ / min and kept for 10-20min, and a pressure of 5-20MPa is applied, then the temperature is raised to 1040℃±10℃ at a speed of ≤3℃ / min and kept for 5-15min, and a pressure of 20-35MPa is applied, and after the end of the insulation, the temperature is lowered to 400℃ at a speed of ≥20℃ / min and then cooled to room temperature with the furnace;

[0045] (5) After sintering, the mold around the prefabricated part is removed, and the prefabricated part is processed by mechanical grinding, wire cutting, laser cutting or water cutting to meet the needs of repairing gas turbine service parts.

[0046] The density of the nickel-based high-temperature alloy repair powder after sintering is greater than 99%.

[0047] Repair: (1) Remove the coating on the gas turbine turbine service parts by mechanical sandblasting. Use mechanical grinding to grind the defects and some microcracks of the gas turbine turbine service parts to form repair pits or grooves. Use alcohol or acetone to clean the repair pits and grooves. (2) Fix the prefabricated parts to the surface of the repair area of ​​the gas turbine turbine service parts by spot welding, and place the gas turbine turbine service parts in a vacuum heat treatment furnace for heat treatment. The heat treatment furnace is raised to 1000℃ at a speed of ≤15℃ / min, and the heat treatment furnace is kept at 1000℃ for 30mins. The heat treatment furnace is raised to 1190℃ at a speed of ≤8℃ / min, and the heat treatment furnace is kept at 1190℃ for 30mins. The heat treatment furnace is lowered to 500℃ at a speed of ≥10℃ / min, and the heat treatment furnace is cooled to room temperature after 500℃. (3) The gas turbine repair component after heat treatment is ground according to the original component shape, and then the overall gas turbine repair component structure is subjected to restorative heat treatment, and finally the coating is re-prepared on the gas turbine repair component.

[0048] Example 3

[0049] Different from Example 2, this example uses In738 nickel-based high-temperature alloy; the low-melting-point alloy powder is prepared according to the ratio provided in No. 2 in Example 1; the high-melting-point alloy powder in the nickel-based high-temperature alloy powder is 70% by weight, and the low-melting-point alloy powder is 30% by weight; in the nickel-based high-temperature alloy repair powder, the binder is 5% by weight, and the nickel-based high-temperature alloy powder is 95%. The rest of the preparation and repair methods are the same as those in Example 2.

[0050] Example 4

[0051] Different from Example 2, this example uses GTD-222 nickel-based high-temperature alloy; the low-melting-point alloy powder is prepared according to the ratio provided in No. 3 in Example 1; the high-melting-point alloy powder in the nickel-based high-temperature alloy powder is 50% by weight, and the low-melting-point alloy powder is 50% by weight; in the nickel-based high-temperature alloy repair powder, the binder is 10% by weight, and the nickel-based high-temperature alloy powder is 90%. The rest of the preparation and repair methods are the same as those in Example 2.

[0052] Example 5

[0053] Repair of damaged prefabricated parts of MarM247 high temperature alloy components

[0054] (1) Pretreatment of the repair area: Use a carbide straight grinder to grind the area to be repaired until it is bright and smooth. The size of the area to be repaired is length × width × depth = 30 mm × 15 mm × 1.5 mm. Clean the polished area with acetone.

[0055] (2) Powder preparation: The low melting point alloy powder composition is as follows by weight percentage: 19.0% Cr, 1.5% W, 8.2% Co, 5.0% Ta, 1.8% Mo, 1.7% Ti, 2.0% Nb, 4.0% Al, 0.15% Zr, 0.1% Hf, 0.0002% Y, 0.007% Ce, 0.005% La, 0.002% Mg, 2.45% B, the rest is Ni and unavoidable impurity elements. The powder particle size is -53μm. The high melting point alloy powder composition is prepared from MarM247 alloy ingot, and the powder particle size is -53μm.

[0056] (3) Powder mixing:

[0057] Calculated by weight percentage: high melting point alloy powder accounts for 60% of the nickel-based high temperature alloy powder, and low melting point alloy powder accounts for 40%.

[0058] Calculated by weight percentage: nickel-based high-temperature alloy powder and binder are evenly mixed to obtain nickel-based high-temperature alloy repair powder, wherein the binder accounts for 15% and the nickel-based high-temperature alloy powder accounts for 85%.

[0059] Preparation of nickel-based high-temperature alloy powder: high melting point alloy powder, low melting point alloy powder and binder are mixed evenly in a powder mixer according to the above proportions.

[0060] (4) Preparation of prefabricated parts:

[0061] The mixed nickel-based high-temperature alloy powder is placed in a mold, and the mold is placed in the effective heating area of ​​a vacuum hot pressing furnace. The vacuum degree of the vacuum hot pressing furnace is 3×10 -3 Pa, the vacuum hot pressing furnace is heated to 900℃±10℃ at a speed of ≤10℃ / min and kept warm for 20-30min, then heated to 1000℃±10℃ at a speed of ≤8℃ / min and kept warm for 10-20min, and a pressure of 5-20MPa is applied, then heated to 1040℃±10℃ at a speed of ≤3℃ / min and kept warm for 5-15min, and a pressure of 20-35MPa is applied, and after the end of the heat preservation, the temperature is reduced to 400℃ at a speed of ≥20℃ / min and then cooled to room temperature with the furnace. After sintering, the mold is removed from the surface of the preform by machining and electric spark wire cutting, and a 32mm×18mm×2mm preform is prepared.

[0062] (5) Prefabricated parts repair

[0063] The cut prefabricated parts were spot welded to the repair area of ​​the MarM247 high-temperature alloy component and placed in the effective heating area of ​​the heat treatment furnace for heat treatment. The vacuum degree of the heat treatment was 5×10 -3 Pa, the heat treatment furnace is increased to 1000℃ at a speed of ≤15℃ / min, the heat treatment furnace is kept at 1000℃ for 30mins, the heat treatment furnace is increased to 1190℃ at a speed of ≤8℃ / min, the heat treatment furnace is kept at 1190℃ for 30mins, the heat treatment furnace is reduced to 500℃ at a speed of ≥10℃ / min, and the heat treatment furnace is cooled to room temperature after 500℃.

[0064] (6) Remanufacturing of MarM247 high temperature alloy components

[0065] The repaired MarM247 high-temperature alloy components are subjected to surface shaping treatment, performance recovery heat treatment and coating preparation to complete the entire process of Mar M247 high-temperature alloy component repair work.

Claims

1. A nickel-based high-temperature alloy prefabricated part for repairing high-temperature components of a gas turbine, characterized in that: The nickel-based high-temperature alloy preform is sintered from nickel-based high-temperature alloy repair powder; the nickel-based high-temperature alloy repair powder comprises high-melting point alloy powder, low-melting point alloy powder and binder; the high-melting point alloy powder and the low-melting point alloy powder are mixed into nickel-based high-temperature alloy powder; the nickel-based high-temperature alloy powder comprises 50% to 70% high-melting point alloy powder and 30% to 50% low-melting point alloy powder by weight percentage; the nickel-based high-temperature alloy powder and the binder are mixed into nickel-based high-temperature alloy repair powder; the nickel-based high-temperature alloy repair powder comprises 85% to 95% nickel-based high-temperature alloy powder and 5% to 15% binder by weight percentage; the low-melting point alloy powder contains 14.00% to 20.00% Cr, 0.2 0% to 1.50% W, 0.50% to 2.00% Mo, 8.00% to 10.00% Co, 2.50% to 5.50% Ta, 3.00% to 4.00% Al, 0.00% to 2.00% Ti, 1.00% to 2.50% Nb, 0.10% to 0.35% Zr, 0.05% to 0.2% Hf, 0.001% to 0.01% Y, 0.005% to 0.01% Ce, 0.001% to 0.01% La, 0.001% to 0.006% Mg, 2.3% to 2.7% B, and the balance is Ni and impurity elements; the high melting point alloy powder is consistent with the material composition of the high temperature parts of the gas turbine to be repaired.

2. The nickel-based high-temperature alloy preform for repairing high-temperature components of a gas turbine according to claim 1, characterized in that: The purity of each component raw material of the low melting point alloy powder is not less than 99.99%.

3. The nickel-based high-temperature alloy preform for repairing high-temperature components of a gas turbine according to claim 1, characterized in that: The particle size of the low melting point alloy powder and the high melting point alloy powder is -53 μm.

4. The nickel-based high-temperature alloy preform for repairing high-temperature components of a gas turbine according to claim 1, characterized in that: The melting temperature of the low melting point alloy powder is 1050°C to 1140°C.

5. A method for preparing a nickel-based high-temperature alloy preform for repairing a high-temperature component of a gas turbine according to any one of claims 1 to 4, characterized in that: The preparation method is: (1) Select nickel-based high-temperature alloy and use a rotating electrode method to prepare and screen the required high-melting-point alloy powder; (2) Ni, Cr, W, Mo, Co, Ta, Al, Ti, Nb, Zr, Hf, Y, Ce, La, Mg, and B are prepared, and then the raw materials are melted into alloy ingots by vacuum induction melting, and the required low melting point alloy powder is prepared and screened by plasma atomization; (3) After mixing the processed high melting point alloy powder and low melting point alloy powder, adding a binder, and then mechanically mixing them uniformly to obtain a nickel-based high temperature alloy repair powder; (4) Placing the nickel-based high-temperature alloy repair powder in a mold and sintering it in a vacuum hot pressing furnace to prepare a preform, with a vacuum degree of <1×10 -3 Pa, the sintering temperature is 50-100°C lower than the melting point of the alloy ingot, and the pressure in the vacuum hot pressing furnace is 0-35MPa; (5) After sintering, the mold around the prefabricated part is removed, and the prefabricated part is processed by mechanical grinding, wire cutting, laser cutting or water cutting to meet the needs of repairing gas turbine service parts.

6. The method for preparing a nickel-based high-temperature alloy preform for repairing a high-temperature component of a gas turbine according to claim 5, characterized in that: The temperature in the vacuum hot pressing furnace is raised to 900°C±10°C at a speed of ≤10°C / min and kept for 20-30min, then raised to 1000°C±10°C at a speed of ≤8°C / min and kept for 10-20min, a pressure of 5-20MPa is applied, then raised to 1040°C±10°C at a speed of ≤3°C / min and kept for 5-15min, a pressure of 20-35MPa is applied, and after the insulation is completed, the temperature is lowered to 400°C at a speed of ≥20°C / min and then cooled to room temperature with the furnace.

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