A method for diffusion bonding of nickel-based superalloys with introduction of diffusional hydrogen

Abstract

The application provides a diffusion welding connection method of nickel-based high-temperature alloy with introduced diffusion hydrogen, and relates to the technical field of welding.The diffusion welding connection method of nickel-based high-temperature alloy with introduced diffusion hydrogen comprises the following steps: electrolytic hydrogen charging is performed on the nickel-based high-temperature alloy in a hydrogen charging solution, the nickel-based high-temperature alloy is used as a cathode, and solid solution hydrogen atoms are introduced into the surface stress layer of the nickel-based high-temperature alloy; the nickel-based high-temperature alloy is taken out from the hydrogen charging solution, washed and dried, two to-be-welded surfaces of the nickel-based high-temperature alloy are abutted and contacted to form a connecting piece, pre-tightening pressure is applied to the connecting piece, vacuumization is performed, and diffusion welding connection is performed. In the electrochemical hydrogen charging method, the nickel-based high-temperature alloy is used as a cathode, the electrolytic hydrogen charging is used to preliminarily remove the oxide film on the surface of the nickel-based high-temperature alloy, and in the step S3, the vacuum environment in the heating process of diffusion welding is utilized, and high-temperature catalysis is relied on to promote the diffusion hydrogen in the nickel-based high-temperature alloy matrix to reduce the oxide film, so that the oxide film is removed from the root.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and more specifically, to a diffusion welding method for nickel-based superalloys that introduces diffusible hydrogen. Background Technology

[0002] Diffusion welding is a solid-state metallurgical bonding technique that relies entirely on interfacial atomic diffusion to achieve interfacial bonding. Therefore, it places extremely stringent requirements on the bonding interface, demanding both a smooth surface and the absence of oxide films, or the presence of existing oxide films with a suitable in-situ removal mechanism. In related technologies, during vacuum diffusion welding of nickel-based superalloys, a dense oxide film forms at the bonding interface from sample preparation to assembly to welding. The presence of this oxide film reduces the quality of the interfacial bond. Common oxide film removal mechanisms include vacuum thermal decomposition and micromechanical fragmentation, which require applying high temperature and high pressure to the joint simultaneously. For thin-walled parts with flow channel-cavity structures, high temperature and high pressure can cause deformation of the weldment, affecting structural accuracy. Summary of the Invention

[0003] The present invention aims to solve the problem that applying high temperature and high pressure to remove the oxide film on nickel-based superalloy joints can cause deformation of the welded parts.

[0004] To address the above problems, this invention provides a diffusion welding method for nickel-based superalloys that introduces diffusible hydrogen.

[0005] This invention provides a diffusion welding method for nickel-based superalloys with the introduction of diffusible hydrogen, comprising the following steps: Step S1: Electrolytically charge hydrogen by placing the nickel-based superalloy in a hydrogen-filled solution, with the nickel-based superalloy serving as the cathode, so that dissolved hydrogen atoms are introduced into the surface stress layer of the nickel-based superalloy. Step S2: Remove the nickel-based superalloy from the hydrogen-filled solution, clean and dry it, and bring the two nickel-based superalloy surfaces to be welded together to form a connector. Apply pre-tightening pressure to the connector. S3: Evacuate to 5×10 -3 Above Pa, the heating rate is 80-120℃ / min, heating to 500-800℃, maintaining the pre-tightening pressure, and holding for 10-30 minutes; S4: Remove diffused hydrogen and perform diffusion welding.

[0006] Optionally, during the hydrogen electrolysis charging process, the current density is 0-10 A / m 2 The hydrogen charging time is 5-120 minutes.

[0007] Optionally, the hydrogen-charging solution is a sodium hydroxide solution with a concentration of 3-5 g / L.

[0008] Optionally, the hydrogen-charging solution comprises NaCl at a concentration of 28-32 g / L and NH4SCN at a concentration of 2-4 g / L.

[0009] Optionally, the hydrogen-charging solution comprises H2SO4 at a concentration of 0.01-0.05 mol / L and NH4SCN at a concentration of 2-4 g / L.

[0010] Optionally, after removing diffusing hydrogen, the diffusion weld joint includes: Step T1: Heat to 900-1100℃ and hold for 10-20 minutes to allow residual diffused hydrogen in the hydrogen trap to escape; Step T2: Maintain 900-1100℃, while increasing the pressure applied to the connector to 3-10MPa, and maintain for 10-30 minutes.

[0011] Optionally, in step S2, anhydrous ethanol is used to clean the nickel-based superalloy.

[0012] Optionally, step S1 may be preceded by... Step S0: Use metallographic sandpaper to polish the nickel-based superalloy surface to be welded, so that the surface roughness Ra of the nickel-based superalloy surface to be welded is required to reach 0.4-0.8μm.

[0013] Optionally, step S0 may further include: ultrasonically cleaning the polished nickel-based superalloy with acetone for 15-20 minutes, rinsing with anhydrous ethanol, and then drying.

[0014] Optionally, the preload pressure is 0.5-1 MPa.

[0015] The beneficial effects of the diffusion welding method for nickel-based superalloys using diffusible hydrogen introduced in this invention are as follows: Employing an electrochemical hydrogen charging method, the nickel-based superalloy acts as the cathode during the electrolytic hydrogen charging process, actively reducing and dissolving the dense and brittle oxide film on the surface of the nickel-based superalloy. This initially removes the oxide film from the surface of the nickel-based superalloy. For thin-walled parts with a flow channel-cavity structure, this avoids the deformation of the weldment caused by high-temperature and high-pressure oxide film removal, maintaining the good structural precision of the nickel-based superalloy. The infiltration of hydrogen reduces the diffusion activation energy of key elements such as Ni, significantly increasing the interdiffusion rate of interfacial atoms, resulting in a significant increase in the reaction layer thickness. It also regulates the evolution of the γ / γ' phase microstructure at the interface, achieving high-quality bonding at temperatures lower than conventional diffusion welding temperatures. This effectively avoids high-temperature grain coarsening of the base material, resulting in a dense, defect-free joint structure and significantly improved mechanical properties. Step S3 utilizes the vacuum environment during the diffusion welding heating process, relying on high-temperature catalysis to promote the reduction of the oxide film by diffusing hydrogen dissolved in the nickel-based superalloy matrix. This removes the oxide film at its source, eliminating the risk of the oxide film breaking down into permanent non-metallic inclusions during the high-temperature and high-pressure conditions of diffusion welding. Furthermore, it allows hydrogen atoms dissolved in the crystal lattice to gain sufficient kinetic energy to diffuse backward and escape from the surface. With the welding interface achieving a tight fit and the oxide film removed, the diffusing hydrogen is removed, and the residual hydrogen concentration in the joint is reduced to below a safe threshold. In summary, the entire method, through the step-by-step synergy of hydrogen-filled plasticizing and film removal and vacuum heating for hydrogen removal and embrittlement prevention, not only utilizes the beneficial effects of hydrogen in the early stages to improve interfacial contact conditions but also promptly eliminates the harmful effects of hydrogen in the later stages, ultimately achieving a high-density, inclusion-free, and crack-free high-quality diffusion weld joint. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of a diffusion welding method for nickel-based superalloys with the introduction of diffusible hydrogen, according to an embodiment of the present invention. Figure 2 This is an electron microscope image of the welded joint connection interface of Example 1; Figure 3 This is an electron microscope image of the welded joint interface in Comparative Example 1. Detailed Implementation

[0017] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0018] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this invention's description is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "comprising" and its variations as used herein are open-ended inclusion, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the description below.

[0019] In related technologies, for vacuum diffusion welding of GH536, the commonly used method is to reduce the oxide film to a nanoscale passivation film before welding; and to remove it in situ using a physicochemical mechanism of high temperature and high pressure during welding. The specific steps are as follows: (1) Use 400#~3000# metallographic sandpaper to grind step by step and polish the surface. The surface roughness Ra is usually required to reach 0.4-0.8μm; (2) First use acetone for ultrasonic cleaning, then rinse with anhydrous ethanol and dry with hot air. After cleaning, assemble and send it into the furnace immediately. The shorter the time interval, the better; (3) Dissolve the nanoscale oxide film in the vacuum furnace through high temperature and high pressure. The process mainly involves the following three mechanisms: ① vacuum thermal decomposition / dissolution mechanism, ② reduction reaction of carbon elements in the alloy, and ③ micro-mechanical crushing. Among them, the vacuum thermal decomposition mechanism requires high vacuum and high temperature to be present during the welding process; since carbon is a trace element that is strictly controlled in GH536 alloy, the effect of reducing the oxide film by carbon elements is very limited and can only play an auxiliary role; the micro-crushing mechanism requires loading the sample. The aforementioned oxide film breakage mechanism relies on high temperature and high pressure. For thin-walled complex structures, high temperature and high pressure can easily cause structural deformation, which in turn can cause the components to fail to meet the usage requirements.

[0020] To address the problems existing in the aforementioned related technologies, embodiments of the present invention provide a diffusion welding method for nickel-based superalloys that introduces diffusible hydrogen.

[0021] like Figure 1 As shown in the figure, an embodiment of the present invention provides a diffusion welding method for nickel-based superalloys that introduces diffusible hydrogen, comprising the following steps: Step S1: Electrolytically charge hydrogen by placing the nickel-based superalloy in a hydrogen-filled solution, with the nickel-based superalloy serving as the cathode, so that dissolved hydrogen atoms are introduced into the surface stress layer of the nickel-based superalloy. Step S2: Remove the nickel-based superalloy from the hydrogen-filled solution, clean and dry it, and bring the two nickel-based superalloy surfaces to be welded together to form a connector. Apply pre-tightening pressure to the connector. S3: Evacuate to 5×10 -3 Above Pa, the heating rate is 80-120℃ / min, heating to 500-800℃, maintaining the pre-tightening pressure, and holding for 10-30 minutes; S4: Remove diffused hydrogen and perform diffusion welding.

[0022] Specifically, in step S3, the vacuum level is evacuated to 5 × 10⁻⁶. -3 The temperature is rapidly increased to 500-800℃ above Pa, utilizing the high temperature to activate the reducing properties of diffusing hydrogen. This causes hydrogen atoms enriched at the residual stress and interface to undergo a reduction reaction with the surface oxide film, generating water vapor and a small amount of hydrogen. The high vacuum environment lowers the decomposition temperature of the oxide and promotes the forward reaction. On the other hand, it removes the generated gaseous products in real time, avoiding secondary contamination at the interface. Maintaining the pre-tightening pressure ensures that the interface remains in close contact, providing an effective interface channel for the reduction reaction. The interface is cleaned by hydrogen reduction chemical cleaning, removing the oxide film barrier that hinders atomic diffusion and creating clean metal contact conditions for inter-atomic diffusion at the interface in the subsequent diffusion welding stage. The hydrogen introduced in the early hydrogen charging stage is consumed, reducing the risk of hydrogen embrittlement, and the residual hydrogen that originally pinned dislocations and caused lattice distortion is removed, thereby releasing residual stress and restoring the local toughness of the material. The combination of heating and short-term holding not only ensures the kinetic requirements of the reduction reaction but also inhibits the coarsening of the base material grains and excessive dissolution of the strengthening phase. Ultimately, it achieves the synergistic effect of film removal and purification, stress relief, and microstructure control, laying a reliable interface and microstructure foundation for low-temperature high-quality diffusion welding.

[0023] In this embodiment, an electrochemical hydrogen charging method is employed. During the electrolytic hydrogen charging process, the nickel-based superalloy serves as the cathode, undergoing electrolytic hydrogen charging in the hydrogen charging solution. This actively reduces and dissolves the dense and brittle oxide film on the surface of the nickel-based superalloy, initially removing the oxide film. For thin-walled parts with a flow channel-cavity structure, this avoids the weldment deformation caused by high-temperature and high-pressure oxide film removal, maintaining the good structural precision of the nickel-based superalloy. The infiltration of hydrogen can reduce the diffusion activation energy of major elements such as Ni, significantly increasing the interdiffusion rate of interfacial atoms, resulting in a significant increase in the reaction layer thickness. It also regulates the evolution of the γ / γ' phase microstructure at the interface, achieving high-quality bonding at temperatures lower than conventional diffusion welding temperatures. This effectively avoids high-temperature grain coarsening of the base material, resulting in a dense, defect-free joint structure and significantly improved mechanical properties. Step S3 utilizes the vacuum environment during the diffusion welding heating process, relying on high-temperature catalysis to promote the reduction of the oxide film by diffusing hydrogen dissolved in the nickel-based superalloy matrix. This removes the oxide film at its source, eliminating the risk of the oxide film breaking down into permanent non-metallic inclusions during the high-temperature and high-pressure conditions of diffusion welding. Furthermore, it allows hydrogen atoms dissolved in the crystal lattice to gain sufficient kinetic energy to diffuse backward and escape from the surface. With the welding interface achieving a tight fit and the oxide film removed, the diffusing hydrogen is removed, and the residual hydrogen concentration in the joint is reduced to below a safe threshold. In summary, the entire method, through the step-by-step synergy of hydrogen-filled plasticizing and film removal and vacuum heating for hydrogen removal and embrittlement prevention, not only utilizes the beneficial effects of hydrogen in the early stages to improve interfacial contact conditions but also promptly eliminates the harmful effects of hydrogen in the later stages, ultimately achieving a high-density, inclusion-free, and crack-free high-quality diffusion weld joint.

[0024] Optionally, during the hydrogen electrolysis charging process, the current density is 0-10 A / m 2 The hydrogen charging time is 5-120 minutes.

[0025] In this optional embodiment, by using a gentle current and controllable time, the removal and plasticization of hydrogen atoms are precisely confined to the surface area of ​​the nickel-based superalloy that needs improvement, while avoiding hydrogen embrittlement penetrating into the nickel-based superalloy matrix, thereby providing the optimal surface condition for subsequent diffusion welding.

[0026] Optionally, the hydrogen-charging solution is a sodium hydroxide solution with a concentration of 3-5 g / L.

[0027] In this optional embodiment, the 3-5 g / L sodium hydroxide solution acts as a "pure hydrogen atom generator," providing active hydrogen atoms in a gentle and efficient manner. This ensures the hydrogen supply required for decoction and plasticization while protecting the matrix and eliminating impurities, guaranteeing that only the beneficial effects of hydrogen are realized without any chemical side effects. The hydrogen-filled solution creates a stable, highly conductive, and non-toxic alkaline electrochemical environment, ensuring that hydrogen atoms can be generated efficiently and purely and enter the nickel matrix, while protecting the nickel surface from corrosion.

[0028] Optionally, the hydrogen-charging solution comprises NaCl at a concentration of 28-32 g / L and NH4SCN at a concentration of 2-4 g / L.

[0029] In this optional embodiment, the core function of the hydrogen permeation solution formulation (high concentration NaCl + trace amounts of NH4SCN) can be summarized as "powerful surface activation and poisoning inhibition recombination" to achieve ultra-high efficiency hydrogen permeation. Specifically, the 28-32 g / L NaCl acts as a strong electrolyte, significantly improving the solution's conductivity and releasing a large amount of active Cl-. - Ions, Cl - It can penetrate and destroy the dense passivation film on the nickel surface, putting the substrate in a highly activated state and significantly reducing the polarization resistance of the electrochemical reaction, thereby greatly increasing the kinetic rate of the cathode hydrogen evolution reaction under the same voltage; while 2-4 g / L of NH4SCN plays the role of a key "poisoning agent", and the SCN it dissociates... - Ions or sulfide species generated by the reaction preferentially adsorb onto the most active catalytic sites on the nickel surface, strongly inhibiting the escape of newly generated active hydrogen atoms that combine to form hydrogen molecules (H2), forcing them to diffuse and penetrate into the nickel lattice with almost 100% probability. The result of the synergistic effect of these two factors is that NaCl ensures a sufficient supply of hydrogen and interfacial reaction activity, while NH4SCN blocks the only path for hydrogen atoms to escape, thereby establishing an extremely high hydrogen concentration gradient and compressive stress field on the nickel surface in a short time, achieving a breakthrough in both depth and concentration.

[0030] Optionally, the hydrogen-charging solution comprises H2SO4 at a concentration of 0.01-0.05 mol / L and NH4SCN at a concentration of 2-4 g / L.

[0031] In this optional embodiment, the core function of the hydrogen permeation solution formulation (low concentration H2SO4 + trace amount of NH4SCN) is to synergistically enhance direct proton supply and surface poisoning, thereby achieving high-efficiency and low-damage hydrogen permeation. Specifically, 0.01-0.05 mol / L dilute H2SO4 acts as a protic acid, directly providing highly active H2SO4. + Unlike alkaline solutions, ions do not undergo water dissociation (H₂O→H₂O) during cathode reduction. + +OH The reaction pathway is shorter and the overpotential is lower, thus enabling a sufficient supply of active hydrogen atoms at extremely low current densities. Simultaneously, dilute sulfuric acid has very weak corrosiveness to the nickel matrix, and combined with short-time hydrogen purging, surface pitting corrosion can be effectively avoided, ensuring interface smoothness. Meanwhile, 2-4 g / L of NH4SCN also fulfills its core function as a hydrogen embrittlement poisoning agent, with the dissociated SCN... -Sulfide species selectively adsorb onto catalytic recombination sites on the nickel surface, strongly inhibiting the combination of hydrogen atoms into hydrogen molecules (H2) and their escape. This forces most active hydrogen atoms to diffuse inward, significantly improving hydrogen penetration efficiency. The synergistic effect of both is that H2SO4 ensures a continuous supply of active hydrogen with few side reactions, while NH4SCN blocks hydrogen escape pathways. Together, they rapidly establish a high-concentration hydrogen gradient on the nickel surface, achieving efficient plasticization and film removal.

[0032] Optionally, after removing diffusing hydrogen, the diffusion weld joint includes: Step T1: Heat to 900-1100℃ and hold for 10-20 minutes to allow residual diffused hydrogen in the hydrogen trap to escape; Step T2: Maintain 900-1100℃, while increasing the pressure applied to the connector to 3-10MPa, and maintain for 10-30 minutes.

[0033] In this optional embodiment, in step T1, the temperature is maintained at 5×10. -3 Under high vacuum and pre-tightening pressure, the temperature is raised to 900-1100℃ and held for 10-20 minutes. Utilizing the thermal activation energy provided by the high temperature, the diffused hydrogen atoms remaining in hydrogen traps such as grain boundaries, dislocations, vacancies, and γ / γ′ phase interfaces during the initial hydrogen charging and reduction processes gain sufficient kinetic energy to overcome the trap's binding energy, recombine into hydrogen molecules, and escape from the crystal lattice. Simultaneously, the high vacuum environment continuously extracts the desorbed hydrogen gas in real time, maintaining an extremely low hydrogen partial pressure within the furnace. This provides a concentration gradient driving force for the continuous outward diffusion of hydrogen, achieving deep desorption. By removing residual diffused hydrogen and reducing the concentration of dissolved hydrogen below the safe threshold, the hidden danger of hydrogen accumulating at defects after welding is fundamentally eliminated, ensuring the long-term service reliability of the joint. High-temperature insulation promotes further interdiffusion and recrystallization of interfacial atoms, making the structure of the joint interface more uniform. At the same time, minimal pressure avoids creep deformation of components at high temperatures. After dehydrogenation, the material restores its intrinsic mechanical properties, realizing a closed-loop process in which the joining process uses hydrogen and the final product is freed from hydrogen, ensuring that the diffusion welded joint has both high density and excellent strength and toughness.

[0034] In step T2, under conditions of maintaining a high temperature of 900-1100℃ and a high vacuum, the welding pressure is increased to 3-10 MPa using a hydraulic system and maintained for 10-30 minutes. The synergistic activation of high temperature and high pressure provides sufficient thermal vibration energy to the atoms on both sides of the interface, enabling them to overcome the energy barrier required for diffusion and migration. The high pressure further crushes the microscopic protrusions at the interface through plastic deformation, expanding the actual contact area and shortening the interatomic distance to within the range of gravitational influence. This promotes the formation of common grains or continuous grain boundaries through interdiffusion of lattice atoms on both sides of the interface, achieving true atomic bonding in a metallurgical sense. The plastic flow energy driven by high pressure effectively closes the initial phase... After cleaning, residual micropores, microcracks, and other interface defects are eliminated, resulting in a weld microstructure with extremely high density and no continuous oxide film interlayer. High-temperature, long-term heat preservation ensures sufficient interdiffusion of major elements such as Ni, Cr, or Al, smoothing the composition and microstructure gradient near the interface and forming a uniform and continuous diffusion transition layer, avoiding performance embrittlement caused by abrupt compositional changes. Under these conditions, the joint strength approaches or even reaches the level of the base material, achieving a high-strength, high-density, and high-reliability connection quality, providing a solid metallurgical guarantee for the subsequent service of the component. At the same time, temperature control during this stage avoids excessive grain coarsening in the base material, balancing the connection quality and the performance of the base material.

[0035] Optionally, in step S2, anhydrous ethanol is used to clean the nickel-based superalloy.

[0036] In this optional embodiment, anhydrous ethanol is used to wash away the hydrogen-filled solution on the surface of the nickel-based superalloy to prevent water stains from remaining on the bonding surface.

[0037] Optionally, step S1 may be preceded by... Step S0: Use metallographic sandpaper to polish the nickel-based superalloy surface to be welded, so that the surface roughness Ra of the nickel-based superalloy surface to be welded is required to reach 0.4-0.8μm.

[0038] Specifically, the nickel-based superalloy surfaces to be welded are mechanically ground and polished stepwise using 400#-3000# metallographic sandpaper. This progressively refined grinding and polishing process removes oxide scale, oil stains, and machining marks from the surfaces to be welded through mechanical removal, resulting in a smooth, clean surface with micro-undulations at the submicron scale. This provides ideal physical contact conditions for atomic interdiffusion at the subsequent diffusion welding interface.

[0039] In this optional embodiment, the grinding and polishing process inevitably introduces a surface plastic deformation layer and residual stress. This residual stress layer is considered a strain energy accumulation layer. Due to the residual stress causing lattice distortion and increased dislocation density, a non-equilibrium microstructure with higher energy is formed. During electrolytic hydrogen charging, this region can serve as a driving force channel for preferential hydrogen atom penetration, because hydrogen atoms tend to concentrate in higher energy locations such as lattice distortion regions and dislocation-dense regions to reduce the system's free energy, thereby achieving hydrogen concentration enrichment in the stress layer on the surface to be welded. The fine surface finish ensures that the surface oxide film is fully exposed and reacts with hydrogen during the hydrogen reduction process, making the cleaning treatment more thorough. The intentionally retained residual stress layer serves as a hydrogen capture pre-field, guiding the hydrogen atoms penetrating during the hydrogen charging stage to accurately concentrate in the surface to be welded. This process does not add extra steps but promotes diffusion, achieving the goal of synergistic effect between mechanical pretreatment and hydrogen regulation, and providing a high-quality weld interface with both physical smoothness and chemical activity for subsequent processes.

[0040] Optionally, step S0 may further include: ultrasonically cleaning the polished nickel-based superalloy with acetone for 15-20 minutes, rinsing with anhydrous ethanol, and then drying.

[0041] In this optional embodiment, acetone ultrasonic cleaning is used to remove surface oil and polishing residue; acetone residue is removed by rinsing with anhydrous ethanol, followed by drying with a hot air blower.

[0042] Optionally, the preload pressure is 0.5-1 MPa.

[0043] In this optional embodiment, on the one hand, the pressure is sufficient to flatten the microscopic roughness and protrusions on the surface to be welded, significantly increasing the actual contact area of ​​the interface and laying the physical contact foundation for subsequent atomic diffusion. Simultaneously, it avoids excessive creep deformation or instability of the thin-walled structure during the heating process due to excessive pressure. On the other hand, this pressure level is just below the material's yield strength, ensuring that the interface remains closed during the preceding intermediate-temperature hydrogen reduction and high-temperature dehydrogenation stages without hindering the smooth escape of water vapor and desorbed hydrogen generated by the hydrogen reduction reaction. This avoids sealing the interface and blocking the gas escape channels due to excessive pressure. In summary, this approach ensures the smooth progress of interface cleaning treatment at each stage, maintains the dimensional accuracy and shape stability of the component, and ensures that the mating surfaces are in a tightly fitted and chemically clean optimal state before entering the high-pressure welding stage, thus providing crucial initial conditions for high-quality diffusion welded joints.

[0044] The present invention will be further described below with reference to specific embodiments.

[0045] Example 1: GH536 diffusion welded joint with diffusing hydrogen.

[0046] 1. Use 400#-3000# metallographic sandpaper to perform progressive mechanical grinding and polishing on the GH536 base material to be welded, so that the surface roughness Ra of the base material to be welded surface reaches 0.6μm. After ultrasonic cleaning with acetone for 18 minutes, rinse with anhydrous ethanol and dry with a hot air blower.

[0047] 2. Electrolytic hydrogen charging was performed by placing GH536 in a 4 g / L sodium hydroxide solution, with GH536 serving as the cathode. This introduced dissolved hydrogen atoms into the surface stress layer of GH536, at a current density of 5 A / m. 2 Hydrogen charging time: 60 minutes.

[0048] 3. Remove GH536 from the hydrogen charging solution, rinse with anhydrous ethanol, and dry. Place the two GH536 surfaces to be welded together to form a connector. Apply a pre-tightening pressure of 1 MPa and evacuate to 5 × 10⁻⁶. -3 .

[0049] 4. The heating rate is 100℃ / min, and the temperature is raised to 700℃. Hold the temperature for 20 minutes.

[0050] 6. Heat to 1000℃ and hold for 15 minutes to allow the residual diffused hydrogen in the hydrogen trap to escape.

[0051] 7. Maintain the temperature at 1000℃, while simultaneously increasing the pressure to 6MPa and holding for 20 minutes to complete the welding.

[0052] 8. Turn off the heating program, maintain the above pressure and vacuum level until the furnace temperature cools to room temperature, and obtain the joint, such as... Figure 2 As shown, the intermediate bonding interface shows no deformation, no non-metallic inclusions, and no cracks.

[0053] Example 2: GH536 diffusion welded connection with the introduction of diffusing hydrogen.

[0054] 1. Use 400#-3000# metallographic sandpaper to perform progressive mechanical grinding and polishing on the GH536 base material to be welded, so that the surface roughness Ra of the base material to be welded surface reaches 0.6μm. After ultrasonic cleaning with acetone for 18 minutes, rinse with anhydrous ethanol and dry with a hot air blower.

[0055] 2. GH536 was placed in a sodium chloride solution with a composition ratio of 30 g / L NaCl and 3 g / L NH4SCN for electrolytic hydrogen charging, with GH536 serving as the cathode. This process introduced dissolved hydrogen atoms into the surface stress layer of GH536, with a current density of 1 A / m. 2 Hydrogen charging time: 120 minutes.

[0056] 3. Remove GH536 from the hydrogen-filled solution, rinse with anhydrous ethanol, and dry. Place the two GH536 surfaces to be welded face to face to form a connector. Apply a pre-tightening pressure of 0.5 MPa and evacuate to 5 × 10⁻⁶. -3 .

[0057] 4. The heating rate is 80℃ / min, and the temperature is raised to 500℃. Hold the temperature for 30 minutes.

[0058] 6. Heat to 900℃ and hold for 20 minutes to allow the residual diffused hydrogen in the hydrogen trap to escape.

[0059] 7. Maintain the temperature at 900℃, while simultaneously increasing the pressure to 10MPa and holding for 30 minutes to complete the welding.

[0060] 8. Turn off the heating program, maintain the above pressure and vacuum level until the furnace temperature cools down to room temperature to obtain the joint.

[0061] Example 3: GH536 diffusion welded joint with diffusing hydrogen.

[0062] 1. Use 400#-3000# metallographic sandpaper to perform progressive mechanical grinding and polishing on the GH536 base material to be welded, so that the surface roughness Ra of the base material to be welded surface reaches 0.6μm. After ultrasonic cleaning with acetone for 18 minutes, rinse with anhydrous ethanol and dry with a hot air blower.

[0063] 2. GH536 was placed in a dilute sulfuric acid solution with a composition of 0.01 mol / L H2SO4 and 3 g / L NH4SCN for electrolytic hydrogen charging, with GH536 as the cathode. This process introduced dissolved hydrogen atoms into the surface stress layer of GH536 at a current density of 10 A / m. 2 Hydrogen charging time: 5 minutes.

[0064] 3. Remove GH536 from the hydrogen charging solution, rinse with anhydrous ethanol, and dry. Place the two GH536 surfaces to be welded together to form a connector. Apply a pre-tightening pressure of 1 MPa and evacuate to 5 × 10⁻⁶. -3 .

[0065] 4. The heating rate is 120℃ / min, heat to 800℃, and hold for 10 minutes.

[0066] 6. Heat to 1100℃ and hold for 10 minutes to allow the residual diffused hydrogen in the hydrogen trap to escape.

[0067] 7. Maintain the temperature at 1100℃, while simultaneously increasing the pressure to 3MPa and holding for 10 minutes to complete the welding.

[0068] 8. Turn off the heating program, maintain the above pressure and vacuum level until the furnace temperature cools down to room temperature to obtain the joint.

[0069] Comparative Example 1: GH536 diffusion welded connection.

[0070] 1. Use 400#-3000# metallographic sandpaper to perform progressive mechanical grinding and polishing on the GH536 base material to be welded, so that the surface roughness Ra of the base material to be welded surface reaches 0.6μm. After ultrasonic cleaning with acetone for 18 minutes, rinse with anhydrous ethanol and dry with a hot air blower.

[0071] 2. The two GH536 surfaces to be welded are brought into contact to form a connector. A preload pressure of 1 MPa is applied, and a vacuum is drawn to 5 × 10⁻⁶. -3 .

[0072] 4. The heating rate is 100℃ / min, and the temperature is raised to 700℃. Hold the temperature for 20 minutes.

[0073] 6. Heat to 1000℃ and keep warm for 15 minutes.

[0074] 7. Maintain the temperature at 1000℃, and simultaneously increase the pressure to 10MPa to break the oxide film on the bonding surface. Hold for 20 minutes to complete the welding.

[0075] 8. Turn off the heating program, maintain the above pressure and vacuum level until the furnace temperature cools to room temperature, and obtain the joint, such as... Figure 3 As shown, the intermediate bonding interface is deformed, and there are permanent non-metallic inclusions generated by the broken particles at the intermediate bonding interface, resulting in a large number of cracks.

[0076] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for diffusion welding of nickel-based superalloys by introducing diffusible hydrogen, characterized in that, Includes the following steps: Step S1: Electrolytically charge the nickel-based superalloy with hydrogen in a hydrogen-filled solution, using the nickel-based superalloy as the cathode, so that dissolved hydrogen atoms are introduced into the surface stress layer of the nickel-based superalloy. Step S2: Remove the nickel-based superalloy from the hydrogen-filled solution, clean and dry it, bring the two nickel-based superalloy surfaces to be welded together to form a connector, and apply a pre-tightening pressure to the connector; S3: Evacuate to 5×10 -3 Above Pa, the heating rate is 80-120℃ / min, heating to 500-800℃, maintaining the pre-tightening pressure, and holding for 10-30 minutes; S4: Remove diffused hydrogen and perform diffusion welding.

2. The method for diffusion welding of nickel-based superalloys with diffusible hydrogen according to claim 1, characterized in that, During the electrolytic hydrogen charging process, the current density is 0-10 A / m 2 The hydrogen charging time is 5-120 minutes.

3. The method for diffusion welding of nickel-based superalloys with diffusible hydrogen according to claim 1, characterized in that, The hydrogen charging solution is a sodium hydroxide solution with a concentration of 3-5 g / L.

4. The diffusion welding method for nickel-based superalloys with diffusible hydrogen according to claim 1, characterized in that, The hydrogen charging solution comprises NaCl at a concentration of 28-32 g / L and NH4SCN at a concentration of 2-4 g / L.

5. The method for diffusion welding of nickel-based superalloys with diffusible hydrogen according to claim 1, characterized in that, The hydrogen charging solution comprises H2SO4 at a concentration of 0.01-0.05 mol / L and NH4SCN at a concentration of 2-4 g / L.

6. The method for diffusion welding of nickel-based superalloys with diffusible hydrogen according to claim 1, characterized in that, The steps of removing diffusing hydrogen and performing diffusion welding include: Step T1: Heat to 900-1100℃ and hold for 10-20 minutes to allow residual diffused hydrogen in the hydrogen trap to escape; Step T2: Maintain 900-1100℃, while increasing the pressure applied to the connector to 3-10MPa and maintaining it for 10-30 minutes.

7. The diffusion welding method for nickel-based superalloys with diffusible hydrogen according to claim 1, characterized in that, In step S2, the nickel-based high-temperature alloy is cleaned using anhydrous ethanol.

8. The method for diffusion welding of nickel-based superalloys with diffusible hydrogen according to claim 1, characterized in that, Before step S1, there are also steps that include... Step S0: Use metallographic sandpaper to polish the surface of the nickel-based high-temperature alloy to be welded, so that the surface roughness Ra of the surface of the nickel-based high-temperature alloy to be welded is required to reach 0.4-0.8μm.

9. The method for diffusion welding of nickel-based superalloys with diffusible hydrogen according to claim 8, characterized in that, Step S0 further includes: ultrasonically cleaning the nickel-based high-temperature alloy after acetone cleaning and polishing for 15-20 minutes, rinsing with anhydrous ethanol, and then drying.

10. The method for diffusion welding of nickel-based superalloys with diffusible hydrogen according to claim 8, characterized in that, The preload pressure is 0.5-1 MPa.

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