Preparation method and application of powder metallurgy nickel-based superalloy for nuclear power field

Abstract

The invention relates to a preparation method of a powder metallurgy nickel-based high-temperature alloy core plate in the nuclear power field. The method comprises the steps that firstly, alloy powder is prefabricated, main elements of the alloy powder are Ni, Cr, Ti, Al and the like, dispersion strengthening is conducted by adding La2O3, Y2O3 and TiN, powder sintering is conducted after ball-milling compounding is conducted, the composite powder obtained after ball milling is loaded into a sheath, compaction degassing and sealing welding are conducted, and then hot isostatic pressing is conducted. And the obtained material is heated to the hot rolling temperature for multi-pass rolling, the final rolling thickness of the core plate is 0.2-0.5 mm, and the high-strength and corrosion-resistant oxidized dispersion high-temperature alloy core plate for nuclear power is obtained. The powder metallurgy high-temperature alloy sheet prepared by the method is etched to obtain a runner, so that the heat exchange core plate is manufactured.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material preparation, and particularly relates to a preparation method and application of a powder metallurgy nickel-based superalloy for the nuclear power field. Background Art

[0002] As a clean and efficient energy source, nuclear energy occupies an important position in the global energy structure. However, during the operation of nuclear power plants, the reactor structural materials are in extreme environments such as high temperature, high pressure, and strong irradiation for a long time, which poses extremely high requirements for the performance of the materials. Traditional superalloys are difficult to meet these harsh conditions, so it is of great significance to develop new high-performance superalloys for nuclear power. Oxide dispersion strengthened (ODS) superalloys significantly improve the high-temperature strength, creep resistance, and irradiation resistance of the alloy by introducing nanoscale oxide particles into the matrix, and are considered ideal candidate materials for the next-generation nuclear reactor structural materials. The main characteristics of superalloys include: excellent high-temperature strength and plasticity, which enable superalloys to maintain sufficient strength and toughness at high temperatures, thus meeting the usage requirements of PCHE under extreme working conditions. Good oxidation resistance and hot corrosion resistance: Superalloys are not easily oxidized and corroded at high temperatures, which helps to extend the service life of PCHE and improve its reliability. Excellent creep resistance and anti-fission performance: These properties enable superalloys to maintain a stable shape and size under high-temperature and high-pressure environments, thus ensuring the heat exchange efficiency of PCHE. Good tissue stability: The tissue structure of superalloys does not easily change at high temperatures, which helps to maintain the long-term performance stability of PCHE. At the same time, superalloys are very difficult to process, mainly reflected in the following aspects such as the hardness and toughness of superalloys: Superalloys usually have high hardness and toughness, which exacerbates the wear of the tool during the etching process and reduces the etching efficiency. High hardness also means that higher etching energy or longer etching time is required, which increases the production cost and cycle. Chemical stability of the material: Some superalloys have high chemical stability to the etching solution and are not easily corroded by the etching solution, thus affecting the etching speed and quality. Materials with strong chemical stability may require the use of special etching solutions or etching processes, which increases the processing difficulty and cost. The etching accuracy requirements of PCHE are usually relatively high, and it is necessary to ensure the width, depth, and shape accuracy of the etching lines. The high-precision requirements make it necessary to strictly control parameters such as the etching speed, the concentration and temperature of the etching solution during the etching process, which increases the difficulty of process control. Undercutting is one of the common problems in the etching process, which will cause the width of the etching line to become larger, affecting the accuracy and performance. The degree of undercutting is affected by various factors such as the type, concentration, temperature of the etching solution, and the structure of the etching equipment, and it is difficult to completely avoid. The surface quality after etching has an important impact on the performance and service life of PCHE. Defects such as burrs and scratches generated during the etching process will affect the surface quality, and thus affect the heat exchange efficiency and sealing performance of PCHE. Summary of the Invention

[0003] The purpose of this section is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this section, the abstract, and the title. Such simplifications or omissions shall not be used to limit the scope of the present invention.

[0004] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0005] The purpose of the present invention is to provide a preparation method and application of powder metallurgy nickel-based superalloy for the nuclear power field. By innovating the material preparation process technology, using high-temperature rolling technologies such as primary and secondary rolling, the superalloy sheets are regulated, the distribution of texture in all directions of the rolled sheets is regulated, and the grain size is refined. Furthermore, while obtaining mechanical properties, corresponding etching technologies and formulations are developed and researched.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: A preparation method and application of powder metallurgy nickel-based superalloy for the nuclear power field, including

[0007] 1. The alloy powder

[0008] a) Preparation of the alloy powder: Nickel-based pre-alloy powder is prepared by argon atomization. The melting alloy composition is Al 0.20 - 0.25%, Cr 19 - 23%, Fe 0.5 - 1%, Ti 0.5 - 1%, Y 0.2 - 0.5%, and the balance is Ni; the powder particle size D50 is 30 - 50 μm;

[0009] b) Select La 2 O 3 , Y 2 O 3 , TiN as the dispersion strengthening and enhancing phase, with a ratio of La 2 O 3 accounting for 40%, Y 2 O 3 accounting for 40%, and TiN accounting for 20%. The particle size D50 is 5 - 10 μm. In order to improve the bonding strength and contact specific surface area of each alloy powder, the dispersion strengthening and enhancing phase is subjected to surface micro-etching. The formula is 10% ammonium bifluoride solution, the soaking time is 20S, and then it is washed with deionized water and dried for standby;

[0010] 2. Mechanical alloying: The raw materials in step 1 are put into a high-energy ball mill according to the ratio of the dispersion strengthening and enhancing phase accounting for 0.3 - 1% of the total mass for mechanical alloying. The ball milling time is 10 - 30 hours, the ball-to-material ratio is 10:1 - 20:1, and the rotation speed is 200 - 400 revolutions per minute;

[0011] 3. Load the mechanically alloyed powder into a stainless steel sheath and perform hot isostatic pressing. The hot isostatic pressing temperature is 1000 - 1200 °C, the pressure is 100 - 150 MPa, and the holding time is 30 - 60 minutes.

[0012] 4. Heat treatment: Heat-treat the billet after hot isostatic pressing. The heat treatment process is as follows: solution treatment at 1100 - 1200 °C for 1 - 2 hours, water quenching, then aging treatment at 700 - 800 °C for 10 - 20 hours, and air cooling.

[0013] 5. Heat the billet to 900 - 1100 °C for hot rolling. Use a lubricant for lubrication during rough rolling and finish rolling. Roll it to a thickness of 0.2 - 1 mm. Finish annealing: Anneal the rolled sheet. The annealing temperature is 950 - 1100 °C, and the holding time is 1 - 3 hours.

[0014] 6. Perform surface treatment and etching on the obtained superalloy sheet. After pickling and degreasing the sheet surface, perform etching to obtain flow channels. It is characterized in that the formula of the etching solution is as follows: the concentration of ammonium cerium nitrate etching solution is 100 - 200 g / L, the concentration of FeCl 3 ion source is 50 g / L - 400 g / L, the proportion of nitric acid is 10 - 20% (volume fraction), and the concentration of the anti-undercutting agent hydroxyethylidene diphosphonic acid is 10 g / L - 20 g / L.

[0015] 7. Etch the superalloy core plate obtained in step 5. It is characterized in that the etching method specifically includes the following steps:

[0016] (1) Perform film covering treatment on the superalloy core plate to be etched. The coating thickness of the photosensitive ink may need to be between 8 and 14 microns. Due to problems such as the strong corrosiveness of the etching solution, polyacrylic acid resin is added to the ink, with a molecular weight between 16000 and 30000; cover a negative film on the film-covered metal plate for exposure treatment, and develop the exposed metal plate.

[0017] (2) The spray pressure for the spray etching operation on the exposed and developed plate is 2.5 - 3 kg / cm2. The spray temperature for the spray etching operation is 40 - 60 °C, and the spray time is 10 - 20 min.

[0018] 8. Perform rapid surface polishing on the etched product obtained in step 7 to reduce the roughness. The polishing solution composition is spherical alumina with a particle size of 80 - 200 nm, accounting for 5% - 10%, sodium polyacrylate dispersant accounting for 2% - 5%, polyvinylpyrrolidone film-forming agent 1% - 2%, and the rest is water, with a neutral pH. The polishing time is 2 - 3 min. After cleaning and drying, the required superalloy heat exchange core plate is obtained.

[0019] The design principle of the present invention is as follows:

[0020] The oxidation resistance and hardness of existing high-temperature alloys are problematic in nuclear power applications, and the heat resistance of traditional iron-based high-temperature alloys cannot meet the requirements. High-temperature alloys improve the mechanical properties of alloys by γ′ phase precipitation. Studies have shown that when the temperature exceeds 1000°C, the γ′ phase will aggregate, grow or re-dissolve in the matrix, thereby losing its strengthening effect. At present, the use temperature of traditional nickel-based high-temperature alloys is close to the limit of the working temperature (Tm). It is difficult to expand the service temperature of high-temperature alloys to a higher service temperature by regulating γ′. ODS high-temperature alloys introduce nano-inert particles with high thermal stability and chemical dispersion in the matrix to improve the stability of the mechanical properties of the alloy by hindering dislocation and grain boundary movement. The addition of oxides, particle size, and the composite situation with the alloy, and the rolling process have an impact on the grain size and orientation. Through ball milling, dispersed particles with a size of 5-10nm are finally formed with a "core-shell" structure. At the same time, the surface of the oxide particles is finely etched to improve the interface contact between the particles and the alloy, and the interface bonding is improved. At the same time, by introducing TiN particles, TiN absorbs oxygen atoms and fuses into the alloy, which better plays a role in dispersion strengthening. At the same time, we developed a high-temperature alloy etching solution formula to achieve a technological breakthrough in PCHE core boards.

[0021] The technical effects of the present invention or the advantages of the present invention compared with the prior art shall be explained and supported by specific data and described in a specific and realistic manner.

[0022] (1) The present invention provides a method for preparing a powder metallurgy nickel-based high-temperature alloy for use in the nuclear power field and its application. By optimizing the high-temperature alloy composition and the amount and ratio of dispersed particles, high strength and high temperature resistance are achieved.

[0023] (2) The high-temperature alloy sheet of the present invention is stronger than the traditional high-temperature alloy and is more suitable for working conditions in the nuclear power field.

[0024] (3) Compared with other patents for high-temperature contract preparation, the present invention can prepare high-temperature alloys and etching formulas, which are suitable for core plates of microchannel heat exchange in the nuclear power field, and have isotropic mechanical properties, which can meet the specifications and performance requirements under nuclear power conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0026] Figure 1 Process diagram for preparing the heat exchange core plate of the superalloy of the present invention.

[0027] Figure 2 Preparing the plate in Example 1 of the present invention.

[0028] Figure 3 Workpiece after etching the plate prepared in Example 1 of the present invention. Detailed implementation manners

[0029] To make the above objects, features and advantages of the present invention more obvious and understandable, the following detailed description of the specific implementation manners of the present invention is made in conjunction with the embodiments of the specification.

[0030] Many specific details are set forth in the following description in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar promotions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0031] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure or characteristic that can be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it an individual or alternative embodiment that excludes other embodiments.

[0032] The following is a detailed description in conjunction with the specific implementation manners.

[0033] Example 1

[0034] 1. The alloy powder

[0035] a) Preparation of the alloy powder: Nickel-based pre-alloy powder was prepared by argon atomization method. The melting alloy composition was Al 0.22%, Cr 21%, Fe 0.8%, Ti 0.8%, Y 0.3%, and the balance was Ni; the powder particle size D50 was 25 μm.

[0036] b) Select La 2 O 3 , Y 2 O 3 , TiN as the dispersion strengthening and reinforcing phase, with a ratio of La 2 O 3 accounting for 40%, Y 2 O 3 , accounting for 40%, and TiN accounting for 20%. The particle size D50 was 10 μm. In order to improve the bonding strength and contact specific surface area of each alloy powder, surface micro-etching was performed on the dispersion strengthening and reinforcing phase. The formula was 10% ammonium bifluoride solution, the soaking time was 20 s, and then it was washed with deionized water and dried for standby.

[0037] 2. Mechanical alloying: The raw materials in Step 1 are put into a high-energy ball mill according to the proportion that the dispersion strengthening reinforcing phase accounts for 0.5% of the total powder mass for mechanical alloying. The ball milling time is 20 hours, the ball-to-material ratio is 10:1 - 20:1, and the rotation speed is 300 revolutions per minute;

[0038] 3. The mechanically alloyed powder is loaded into a stainless steel jacket for hot isostatic pressing. The hot isostatic pressing temperature is 1100 °C, the pressure is 150 MPa, and the holding time is 50 minutes;

[0039] 4. Heat treatment: The billet after hot isostatic pressing is heat-treated. The heat treatment process is: solution treatment at 1150 °C for 1.5 hours, water quenching, and then aging treatment at 750 °C for 15 hours, air cooling;

[0040] 5. The billet is heated to 1000 °C for hot rolling. Lubricant is used for lubrication during rough rolling and finish rolling, and it is hot rolled to a thickness of 0.5 mm. Finish annealing: The sheet after finish rolling is subjected to finish annealing. The annealing temperature is 1050 °C, and the holding time is 2 hours.

[0041] 6. The obtained superalloy sheet is subjected to surface treatment and etching. After pickling and degreasing the sheet surface, etching is carried out to obtain a flow channel. It is characterized in that the formula of the etching solution is: the concentration of ammonium cerium nitrate etching solution is 200 g / L, the concentration of the FeCl 3 ion source is 300 g / L, the proportion of nitric acid is 15% (volume fraction), and the concentration of the anti-undercutting agent hydroxyethylidene diphosphonic acid is 15 g / L;

[0042] 7. The superalloy core plate obtained in Step 5 is etched. It is characterized in that the etching method specifically includes the following steps:

[0043] (1) The to-be-etched superalloy core plate is subjected to film covering treatment. The coating thickness of the photosensitive ink may need to be between 12 microns. Due to problems such as the strong corrosiveness of the etching solution, polyacrylic resin is added to the ink, and the molecular weight is between 16000 - 20000; A negative film is covered on the film-covered metal plate for exposure treatment, and the exposed metal plate is developed;

[0044] (2) The spray pressure for the spray etching operation on the exposed and developed sheet is 3 kg / cm2. The spray temperature for the spray etching operation is 50 °C, and the spray time is 15 min.

[0045] 8. Perform rapid surface polishing on the etched product obtained in step 7 to reduce roughness. The polishing liquid consists of spherical alumina with a particle size of 100 nm, accounting for 8%, sodium polyacrylate dispersant accounting for 3%, and polyvinylpyrrolidone film-forming agent accounting for 1%. The rest is water, with a neutral pH. The polishing time is 2 min. After cleaning and drying, the required superalloy heat exchange core plate is obtained.

[0046] Comparative Example 1

[0047] Change the formula of the ceramic reinforcing phase: b) Select La 2 O 3 , with a particle size D50 of 10 μm. To improve the bonding strength and contact specific surface area of each alloy powder, perform surface micro-etching on the dispersion-strengthened reinforcing phase. The formula is 10% ammonium bifluoride solution, soak for 20 s, then wash with deionized water and dry for standby;

[0048] Others are the same as in Example 1.

[0049] Comparative Example 2

[0050] Change the formula of the ceramic reinforcing phase: b) Select Y 2 O 3 , with a particle size D50 of 10 μm. To improve the bonding strength and contact specific surface area of each alloy powder, perform surface micro-etching on the dispersion-strengthened reinforcing phase. The formula is 10% ammonium bifluoride solution, soak for 20 s, then wash with deionized water and dry for standby;

[0051] Others are the same as in Example 1.

[0052] Comparative Example 3

[0053] b) Select La 2 O 3 , Y 2 O 3 as the dispersion-strengthened reinforcing phase, with a ratio of La 2 O 3 accounting for 50%, Y 2 O 3 , accounting for 50%, TiN accounting for 20%, with a particle size D50 of 10 μm. To improve the bonding strength and contact specific surface area of each alloy powder, perform surface micro-etching on the dispersion-strengthened reinforcing phase. The formula is 10% ammonium bifluoride solution, soak for 20 s, then wash with deionized water and dry for standby;

[0054] Others are the same as in Example 1.

[0055] Comparative Example 4

[0056] The obtained superalloy sheet is subjected to surface treatment and etching. After pickling and degreasing the sheet surface, etching is carried out to obtain the flow channels. It is characterized in that the formula of the etching solution is as follows: the concentration of ammonium cerium nitrate etching solution is 100 g / L, and the concentration of the 3 FeCl ion source is 300 g / L, the proportion of nitric acid is 15% (volume fraction), and the concentration of the anti-undercutting agent hydroxyethylidene diphosphonic acid is 15 g / L;

[0057] Others are the same as in Example 1.

[0058] Comparative Example 5

[0059] The obtained superalloy sheet is subjected to surface treatment and etching. After pickling and degreasing the sheet surface, etching is carried out to obtain the flow channels. It is characterized in that the formula of the etching solution is as follows: the concentration of ammonium cerium nitrate etching solution is 200 g / L, and the concentration of the 3 FeCl ion source is 100 g / L, the proportion of nitric acid is 15% (volume fraction), and the concentration of the anti-undercutting agent hydroxyethylidene diphosphonic acid is 15 g / L;

[0060] Others are the same as in Example 1.

[0061] Comparative Example 6

[0062] The obtained superalloy sheet is subjected to surface treatment and etching. After pickling and degreasing the sheet surface, etching is carried out to obtain the flow channels. It is characterized in that the formula of the etching solution is as follows: the concentration of ammonium cerium nitrate etching solution is 200 g / L, and the concentration of the 3 FeCl ion source is 100 g / L, the proportion of nitric acid is 15% (volume fraction); others are the same as in Example 1.

[0063]

[0064]

[0065] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims

1. A method for preparing a powder metallurgy nickel-based high-temperature alloy core plate for use in the nuclear power field, characterized in that: Ingredients: a) Preparation of alloy powder: nickel-based pre-alloyed powder was prepared by argon atomization method, the smelting alloy composition was Al0.20-0.25%, Cr19-23%, Fe0.5-1%, Ti0.5-1%, Y0.2-0.5%, and the balance was Ni; the powder particle size D50 was 30-50μm; b) La2O3, Y2O3, and TiN are selected as dispersion strengthening reinforcement phases with a particle size D50 of 5-10 μm. In order to improve the bonding strength and contact specific surface area of ​​each alloy powder, the dispersion strengthening reinforcement phase is surface micro-etched with a formula of 10% ammonium bifluoride solution and soaked for 20 seconds. After washing with deionized water, ball milling, rolling, and etching are performed to obtain a high-temperature alloy heat exchange core plate.

2. The alloy and reinforcing phase powder ball milling according to claim 1, characterized in that Mechanical alloying: The raw materials in step 1 are placed in a high-energy ball mill for mechanical alloying according to a dispersion strengthening phase accounting for 0.3-1% of the total mass ratio. The ball milling time is 10-30 hours, the ball-to-material ratio is 10:1-20:1, and the rotation speed is 200-400 rpm.

3. The rolling process according to claim 1, characterized in that The mechanically alloyed powder is placed in a stainless steel package and hot isostatic pressing is performed. The hot isostatic pressing temperature is 1000-1200°C, the pressure is 100-150MPa, and the insulation time is 30-60 minutes.

4. The rolling process according to claim 1, characterized in that Heat treatment: The hot isostatic pressing blank is heat treated, and the heat treatment process is: 1100-1200℃ solid solution treatment for 1-2 hours, water quenching, and then 700-800℃ aging treatment for 10-20 hours, air cooling.

5. The rolling process according to claim 1, characterized in that The billet is heated to 900-1100℃ for hot rolling, lubricated with lubricant during rough rolling and finish rolling, hot rolled to a thickness of 0.2-1mm, finished product annealing: the finished plate is annealed at a temperature of 950-1100℃ and a holding time of 1-3 hours.

6. The sheet material according to claim 1 is processed, characterized in that The obtained high-temperature alloy plate is subjected to surface treatment and etching, and after the surface of the plate is pickled and degreased, the flow channel is obtained by etching, characterized in that the formula of the etching solution is as follows: the concentration of the cerium ammonium nitrate etching solution is 100-200g / L, the concentration of the FeCl3 ion source is 50g / L~400g / L, the proportion of nitric acid is 10-20% (volume fraction), and the concentration of the side corrosion inhibitor hydroxyethylidene diphosphonic acid is 10g / L-20g / L.

7. The method for etching the high temperature alloy core plate according to claim 1, characterized in that: The etching method specifically comprises the following steps: (1) The high-temperature alloy core plate to be etched is subjected to a coating treatment, and the thickness of the photosensitive ink coating may need to be between 8 and 14 microns. Due to the strong corrosiveness of the etching solution and other problems, polyacrylic acid resin is added to the ink, and the molecular weight is between 16000 and 30000; a negative film is covered on the coated metal plate for exposure treatment, and the exposed metal plate is developed; (2) The spray pressure for spray etching of the exposed and developed plate is 2.5-3 kg / cm2. The spray temperature for spray etching is 40-60°C and the spray time is 10-20 minutes.

8. The etching content according to claim 1, characterized in that The etched product is quickly polished to reduce the roughness. The polishing liquid is composed of spherical alumina with a particle size of 80-200nm, accounting for 5% to 10%, sodium polyacrylate dispersant accounting for 2% to 5%, polyethylene polyvinyl pyrrolidone film-forming agent 1% to 2%, and the rest is water. The pH is neutral. The polishing time is 2-3 minutes. After cleaning and drying, the required high-temperature alloy heat exchange core plate is obtained.

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