Diffusion bonding method for GH600 high-temperature alloy and copper-silver-zinc alloy

Abstract

The invention discloses a GH600 high-temperature alloy and copper-silver-zinc alloy diffusion bonding method which is characterized in that in the alloy diffusion bonding process, the diffusion temperature is strictly controlled to be 670-700 DEG C and is close to the solid-liquid transition temperature of a BAg49CuZnMnNi intermediate layer, the Mn element can be combined with oxygen of an interface, the combination of oxygen and Cr element in GH600 is eliminated, and the bonding strength of the GH600 high-temperature alloy and the copper-silver-zinc alloy is improved. And meanwhile, Mn and Ni elements have good solid solubility with the Cr element at the high temperature, precipitation of the Cr element can be reduced, enrichment of the Cr element on an interface is avoided, and the problem that in the diffusion bonding process of the GH600 high-temperature alloy and the copper-silver-zinc alloy, the Cr element is precipitated on the interface to be enriched, a CrP brittle phase is generated, and the welding performance of the alloy is reduced is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature alloy diffusion bonding, and more specifically, to a diffusion bonding method for GH600 high-temperature alloy and copper-silver-zinc alloy. Background Art

[0002] The sealing components of a certain type of engine are brazed by GH600 high-temperature alloy and copper-silver-zinc alloy. Copper-silver-zinc alloy is an ideal sealing material due to its low hardness and high linear expansion coefficient. However, the linear expansion coefficients of GH600 high-temperature alloy and copper-silver-zinc alloy are very different, about 2 times, and the service working temperature is high. Therefore, the brazed sealing components are subject to hot and cold stress cycles and the scraping force of the object on copper-silver-zinc during use, which is prone to problems such as peeling and stratification of the connection layer, and even weld cracking after use.

[0003] In order to achieve the effective connection of the sealing structure with large difference in linear expansion coefficient between GH600 high temperature alloy and copper-silver-zinc alloy, CN109759794A discloses the use of hot isostatic pressing diffusion connection technology in a method for connecting copper-silver alloy with a high temperature alloy ring. An intermediate layer of solder is used between the high temperature alloy ring and the copper-silver alloy ring, so that the copper-silver alloy forms a diffusion connection with the high temperature alloy ring under high temperature and high pressure environment, forming a connection between the high temperature alloy and the copper-silver alloy. This patent can achieve reliable connection between high temperature alloy and copper-silver alloy, form a functional integrated structural part, enhance its connection strength, and avoid problems such as peeling and delamination of the connection layer. However, the GH600 high temperature alloy used in this patent contains Cr element. During the diffusion process of heating to 705-745℃, pressure 130-150MPa, and heat preservation and pressure maintenance for 0.25-0.5h, the diffusion rate of Cr in the GH600 alloy is low, and it is easy to produce CrP brittle phase at the connection interface with P in the copper-silver-zinc alloy parent material, resulting in a decrease in weld performance and cracking caused by insufficient weld strength. Summary of the invention

[0004] The main technical problem to be solved by the present invention is to provide a diffusion bonding method for GH600 high-temperature alloy and copper-silver-zinc alloy, aiming at the problem that in the existing GH600 high-temperature alloy and copper-silver-zinc alloy diffusion bonding process, Cr element precipitates and accumulates at the interface to produce CrP brittle phase, resulting in a decrease in the welding performance of the alloy.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A method for diffusion bonding of a GH600 high temperature alloy and a copper-silver-zinc alloy, the preparation steps comprising:

[0007] S1. placing the copper-silver-zinc alloy inner ring into the GH600 high-temperature alloy outer ring, and adding a silver-based alloy intermediate layer between the outer wall of the copper-silver-zinc alloy inner ring and the inner wall of the GH600 high-temperature alloy outer ring;

[0008] S2. Assemble the GH600 high temperature alloy outer ring, the silver-based alloy middle layer and the copper-silver-zinc alloy inner ring and place them in the package, vacuum seal and weld them, and perform hot isostatic pressing;

[0009] S3. Raise the temperature to 670-700°C, the pressure to 160-180 MPa, and keep warm for 40-70 minutes;

[0010] S4. Cooling under pressure, venting and depressurizing after cooling to below 150°C, and removing the jacket to obtain GH600 high temperature alloy and copper-silver-zinc alloy formed parts.

[0011] Furthermore, the thickness of the silver-based alloy intermediate layer is 0.08-0.12 mm.

[0012] Furthermore, the silver-based alloy intermediate layer is made of BAg49CuZnMnNi material.

[0013] Furthermore, the heating process includes: first heating to 300-400°C with a pressure not less than 100 MPa, and then heating to 670-700°C with a pressure of 160-180 MPa.

[0014] Further, the temperature is raised to 680-690°C and the pressure is 165-175MPa. Preferably, the temperature is raised to 685°C and the pressure is 170MPa.

[0015] Furthermore, the heating rate is 4-6°C / min.

[0016] Furthermore, the cooling rate is 1.5-2.5°C / min.

[0017] Furthermore, the contact surface of the copper-silver-zinc alloy inner ring or the GH600 high-temperature alloy outer ring is an uneven surface.

[0018] Furthermore, the uneven surface includes a comb tooth surface, a thread surface or a step surface.

[0019] Compared with the prior art, the beneficial effects are:

[0020] In the process of alloy diffusion connection, the present invention strictly controls the diffusion temperature at 670℃-700℃, which is near the solid-liquid transition temperature of BAg49CuZnMnNi. The Mn element can combine with oxygen at the interface to eliminate the combination of oxygen and Cr element in GH600. At the same time, Mn and Ni elements have good solid solubility with Cr element at high temperature, which can reduce the precipitation of Cr element and avoid the enrichment of Cr element at the interface. When the temperature is too low, that is, below 670℃, the silver-based alloy middle layer is solid, the diffusion rate of alloy elements is low, and a long diffusion time is required to form a better connection interface. In addition, the diffusion process is unstable, which is easy to cause thermal damage to the copper-silver-zinc parent material; when the temperature is too high, that is, when it is greater than 700℃, the brittle phase CrP is easy to be generated, which affects the strength of the weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the package cover;

[0022] Figure 2 It is a schematic diagram of the U-shaped ring of the package;

[0023] Figure 3 It is a schematic diagram of the metallographic diagram of the welds of Examples 1 to 3 and Comparative Example 1;

[0024] Figure 4 It is the fracture detection diagram of Examples 1 to 3 and Comparative Example 1.

[0025] Among them, (a) is the detection diagram of Example 1, (b) is the detection diagram of Example 2, (c) is the detection diagram of Example 3, and (d) is the detection diagram of Comparative Example 1. DETAILED DESCRIPTION

[0026] The present invention will be further explained and illustrated below in conjunction with the embodiments, but the specific embodiments do not limit the present invention in any form.

[0027] The package used in the embodiment is composed of a cover plate and a U-shaped ring, such as Figures 1-2A gap of 0.1 to 0.15 mm is reserved on one side at the joint between the cover plate and the U-shaped ring, the lower surface of the cover plate has a fillet of about 0.5 mm, and a gap of 0.5 mm is reserved between the cover plate and the upper end surface of the part. At the same time, 8 evenly distributed square grooves a are designed on the lower surface of the cover plate, which penetrate radially, with a groove width of about 5 to 6 mm and a groove depth of about 0.3 to 0.5 mm, and; 8 evenly distributed small air guide grooves b are designed on the inner and outer walls of the cover plate, which penetrate axially, with a groove width of about 0.3 to 0.5 mm and a groove depth of about 0.3 to 0.5 mm, and are connected to the 8 square grooves a. A 0.3-0.5mm gap is reserved between the inner and outer side walls of the U-shaped ring and the contact part. An annular groove c and 8 evenly distributed arc air guide grooves d are designed at the bottom. The annular groove and arc air guide groove are about 5-6mm wide and 0.3-0.5mm deep, and are radially connected. Eight arc air guide grooves e are designed on the inner and outer side walls of the U-shaped ring, with a depth of about 0.3mm-0.5mm. The bottom square groove is connected to the side wall air guide groove. This design can ensure that after the parts are installed, the internal gas can be discharged smoothly through the air groove.

[0028] Example 1

[0029] This embodiment provides a diffusion bonding method for GH600 high temperature alloy and copper-silver-zinc alloy, and the preparation steps include:

[0030] S1. Use white silk cloth to scrub the sheath, GH600 high-temperature alloy outer ring, copper-silver-zinc inner ring, and silver-based alloy middle layer. After cleaning, wipe with white silk cloth and it should not change color. Use alcohol as the medium to ultrasonically clean the polished and cleaned middle layer, GH600 high-temperature alloy outer ring, copper-silver-zinc inner ring, sheath cover plate and U-shaped ring. The cleaning time is 10 to 15 minutes. After cleaning, use cold air to dry the surface moisture of the parts and sheath.

[0031] S2. Use the energy storage spot welding method to spot weld the 0.1mm thick BAg49CuZnMnNi silver-based alloy middle layer to the copper-silver-zinc inner ring welding surface. The positioning weld should avoid oxidation and burrs. Combine the GH600 high-temperature alloy outer ring and the copper-silver-zinc alloy inner ring and put them into the encapsulated U-shaped ring. Cover the cover plate so that the air guide groove on the side wall of the cover plate is located in the middle of the air guide square groove on the side wall of the U-shaped ring. Use a punch to impact and position along the gap between the cover plate and the U-shaped ring to ensure that the gap between the cover plate and the U-shaped ring is uniform and the exhaust channel is unobstructed.

[0032] S3. Extract the gas inside the package and perform vacuum sealing welding. Put the sealed package into the hot isostatic pressing furnace, fill the hot isostatic pressing furnace with an appropriate amount of argon gas to ensure that the pressure inside the furnace is 26MPa.

[0033] S4. Raise the temperature at a heating rate of 4°C / min, and inject argon into the furnace through a pressurizer; when the temperature and pressure are raised to 300°C, the pressure must be greater than 100MPa; continue to raise the temperature to 670°C, the solidus temperature of the copper-silver-zinc alloy base material, and ensure the pressure is 160MPa, and maintain the temperature and pressure for 70 minutes. Under high temperature and high pressure conditions, the sheath is deformed by air pressure, forcing the high-temperature alloy and the copper-silver-zinc alloy (silver-based alloy middle layer) to fit closely to cause element diffusion and form a diffusion welding connection.

[0034] S5. Cool at a cooling rate of 1.5°C / min. Do not release air during the cooling process. Release air and release pressure when the temperature reaches below 150°C.

[0035] Example 2

[0036] This embodiment provides a diffusion bonding method for GH600 high temperature alloy and copper-silver-zinc alloy, and the preparation steps include:

[0037] S1. Use white silk cloth to scrub the sheath, GH600 high-temperature alloy outer ring, copper-silver-zinc inner ring, and silver-based alloy middle layer. After cleaning, wipe with white silk cloth and it should not change color. Use alcohol as the medium to ultrasonically clean the polished and cleaned middle layer, GH600 high-temperature alloy outer ring, copper-silver-zinc inner ring, sheath cover plate and U-shaped ring. The cleaning time is 10 to 15 minutes. After cleaning, use cold air to dry the surface moisture of the parts and sheath.

[0038] S2. Use the energy storage spot welding method to spot weld the 0.1mm thick BAg49CuZnMnNi silver-based alloy middle layer to the copper-silver-zinc inner ring welding surface. The positioning weld should avoid oxidation and burrs. Combine the GH600 high-temperature alloy outer ring and the copper-silver-zinc alloy inner ring and put them into the encapsulated U-shaped ring. Cover the cover plate so that the air guide groove on the side wall of the cover plate is located in the middle of the air guide square groove on the side wall of the U-shaped ring. Use a punch to impact and position along the gap between the cover plate and the U-shaped ring to ensure that the gap between the cover plate and the U-shaped ring is uniform and the exhaust channel is unobstructed.

[0039] S3. Extract the gas inside the package and perform vacuum sealing welding. Put the sealed package into the hot isostatic pressing furnace, fill the hot isostatic pressing furnace with an appropriate amount of argon gas to ensure that the pressure inside the furnace is 30MPa.

[0040] S4. Raise the temperature at a heating rate of 6°C / min, and inject argon into the furnace through a pressurizer; when the temperature and pressure are raised to 400°C, the pressure must be greater than 100MPa; continue to raise the temperature to 700°C, which is the solidus temperature of the copper-silver-zinc alloy base material, and ensure the pressure is 180MPa, and maintain the temperature and pressure for 40 minutes. Under high temperature and high pressure conditions, the sheath is deformed by gas pressure, forcing the high-temperature alloy and the copper-silver-zinc alloy (silver-based alloy middle layer) to fit closely to cause element diffusion and form a diffusion welding connection.

[0041] S5. Cool at a cooling rate of 2.5°C / min. Do not release air during the cooling process. Release air and release pressure when the temperature reaches below 150°C.

[0042] Example 3

[0043] This embodiment provides a diffusion bonding method for GH600 high temperature alloy and copper-silver-zinc alloy, and the preparation steps include:

[0044] S1. Use white silk cloth to scrub the sheath, GH600 high-temperature alloy outer ring, copper-silver-zinc inner ring, and silver-based alloy middle layer. After cleaning, wipe with white silk cloth and it should not change color. Use alcohol as the medium to ultrasonically clean the polished and cleaned middle layer, GH600 high-temperature alloy outer ring, copper-silver-zinc inner ring, sheath cover plate and U-shaped ring. The cleaning time is 10-15 minutes. After cleaning, use cold air to dry the surface moisture of the parts and sheath.

[0045] S2. Use the energy storage spot welding method to spot weld the 0.1mm thick BAg49CuZnMnNi silver-based alloy middle layer to the copper-silver-zinc inner ring welding surface. The positioning weld should avoid oxidation and burrs. Combine the GH600 high-temperature alloy outer ring and the copper-silver-zinc alloy inner ring and put them into the encapsulated U-shaped ring. Cover the cover plate so that the air guide groove on the side wall of the cover plate is located in the middle of the air guide square groove on the side wall of the U-shaped ring. Use a punch to impact and position along the gap between the cover plate and the U-shaped ring to ensure that the gap between the cover plate and the U-shaped ring is uniform and the exhaust channel is unobstructed.

[0046] S3. Extract the gas inside the package and perform vacuum sealing welding. Put the sealed package into the hot isostatic pressing furnace, fill the hot isostatic pressing furnace with an appropriate amount of argon gas to ensure that the pressure inside the furnace is 30MPa.

[0047] S4. Raise the temperature at a heating rate of 5°C / min, and inject argon into the furnace through a pressurizer; when the temperature and pressure are raised to 350°C, the pressure must be greater than 100MPa; continue to raise the temperature to 685°C, the solidus temperature of the copper-silver-zinc alloy base material, and ensure the pressure is 170MPa, and maintain the temperature and pressure for 50 minutes. Under high temperature and high pressure conditions, the sheath is deformed by air pressure, forcing the high-temperature alloy and the copper-silver-zinc alloy (silver-based alloy middle layer) to fit closely to cause element diffusion and form a diffusion welding connection.

[0048] S5. Cool at a cooling rate of 2°C / min. Do not release air during the cooling process. Release air and release pressure when the temperature reaches below 150°C.

[0049] Comparative Example 1

[0050] This comparative example provides a diffusion bonding method for GH600 high temperature alloy and copper-silver-zinc alloy, and the preparation steps include:

[0051] S1. Use white silk cloth to scrub the sheath, GH600 high temperature alloy outer ring, copper-silver-zinc inner ring. After cleaning, wipe with white silk cloth and it should not change color. Use alcohol as the medium to ultrasonically clean the GH600 high temperature alloy outer ring, copper-silver-zinc inner ring, sheath cover and U-shaped ring after grinding and cleaning. After cleaning, use cold air to dry the surface moisture of the parts and sheath.

[0052] S2. Assemble the GH600 high-temperature alloy outer ring and the copper-silver-zinc alloy inner ring and put them into the encapsulated U-shaped ring, cover the cover plate, make the air guide groove on the side wall of the cover plate located in the middle of the air guide square groove on the side wall of the U-shaped ring, use a punch to impact and position along the gap between the cover plate and the U-shaped ring to ensure that the gap between the cover plate and the U-shaped ring is uniform and the exhaust channel is unobstructed.

[0053] S3. Extract the gas inside the package and perform vacuum sealing welding. Put the sealed package into the hot isostatic pressing furnace, fill the hot isostatic pressing furnace with an appropriate amount of argon gas to ensure that the pressure inside the furnace is 30MPa.

[0054] S4. Raise the temperature at a heating rate of 5°C / min, and inject argon into the furnace through a pressurizer; raise the temperature and pressure to 350°C to ensure that the pressure is greater than 100MPa; continue to raise the temperature to 710°C, ensure that the pressure is 150MPa, and maintain the temperature and pressure for 25 minutes. Under high temperature and high pressure conditions, the gas pressure deforms the sheath, forcing the high-temperature alloy and the copper-silver-zinc alloy (silver-based alloy middle layer) to fit closely to cause element diffusion and form a diffusion welding connection.

[0055] S5. Cool at a cooling rate of 2°C / min. Do not release air during the cooling process. Release air and release pressure when the temperature reaches below 150°C.

[0056] Metallographic characterization and strength performance testing were performed on the welds and fracture surfaces of the GH600 high temperature alloy and copper-silver-zinc alloy molded parts of Examples 1 to 3 and the comparative example. Figure 1 As shown in the figure, at 670℃-700℃, the weld metallographic structure is uniform, while at 710℃, obvious gray spots of CrP brittle phase can be seen in the metallographic diagram. Figure 2 As shown in the figure, although the connection between copper, silver, zinc and GH600 can be achieved at 710℃, CrP brittle phase is generated inside the weld. The higher the temperature, the more obvious the CrP brittle phase is, and the easier it is to aggregate. The high temperature has a greater impact on the thermal damage of the matrix. From the fracture morphology, the 710℃ weld fracture has fewer dimple features, and the joint fractures brittlely. The detected weld strength is shown in Table 1:

[0057] Table 1

[0058] Example Strength (MPa) Example 1 332～341 Example 2 335～352 Example 3 340～348 Comparative Example 1 300～320

[0059] It can be seen from the above table that the weld strength obtained by the method of the present invention at 670°C-690°C is 332-352MPa, and further increasing the temperature will generate CrP brittle phase, resulting in a decrease in weld strength.

[0060] Example 4

[0061] This embodiment provides a diffusion bonding method for GH600 high temperature alloy and copper-silver-zinc alloy, and the preparation steps include:

[0062] S1. Use white silk cloth to scrub the sheath, GH600 high-temperature alloy outer ring, copper-silver-zinc inner ring, and silver-based alloy middle layer. After cleaning, wipe with white silk cloth and it should not change color. Among them, the inner wall of the GH600 high-temperature alloy outer ring is provided with a comb structure, and the outer wall of the copper-silver-zinc inner ring is also provided with a matching comb structure. Use alcohol as the medium to ultrasonically clean the polished and cleaned middle layer, GH600 high-temperature alloy outer ring, copper-silver-zinc inner ring, sheath cover plate and U-shaped ring. The cleaning time is 10-15 minutes. After cleaning, use cold air to dry the surface moisture of the parts and sheath.

[0063] S2. Use the energy storage spot welding method to spot weld the 0.1mm thick BAg49CuZnMnNi silver-based alloy middle layer to the copper-silver-zinc inner ring welding surface. The positioning weld should avoid oxidation and burrs. Combine the GH600 high-temperature alloy outer ring and the copper-silver-zinc alloy inner ring and put them into the encapsulated U-shaped ring. Cover the cover plate so that the air guide groove on the side wall of the cover plate is located in the middle of the air guide square groove on the side wall of the U-shaped ring. Use a punch to impact and position along the gap between the cover plate and the U-shaped ring to ensure that the gap between the cover plate and the U-shaped ring is uniform and the exhaust channel is unobstructed.

[0064] S3. Extract the gas inside the package and perform vacuum sealing welding. Put the sealed package into the hot isostatic pressing furnace, fill the hot isostatic pressing furnace with an appropriate amount of argon gas to ensure that the pressure inside the furnace is 30MPa.

[0065] S4. Raise the temperature at a heating rate of 5°C / min, and inject argon into the furnace through a pressurizer; when the temperature and pressure are raised to 350°C, the pressure must be greater than 100MPa; continue to raise the temperature to 690°C, the solidus temperature of the copper-silver-zinc alloy base material, and ensure the pressure is 175MPa, and maintain the temperature and pressure for 60 minutes. Under high temperature and high pressure conditions, the sheath is deformed by air pressure, forcing the high-temperature alloy and the copper-silver-zinc alloy (silver-based alloy middle layer) to fit closely to cause element diffusion and form a diffusion welding connection.

[0066] S5. Cool at a cooling rate of 2°C / min. Do not release air during the cooling process. Release air and release pressure when the temperature reaches below 150°C.

[0067] In this embodiment, the inner wall of the GH600 high-temperature alloy outer ring and the outer wall of the copper-silver-zinc inner ring can also be provided with a threaded surface and a step surface to increase the contact area between the two.

[0068] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A diffusion bonding method for GH600 high temperature alloy and copper-silver-zinc alloy, characterized in that: The preparation steps include: S1. placing the copper-silver-zinc alloy inner ring into the GH600 high-temperature alloy outer ring, and adding a silver-based alloy intermediate layer between the outer wall of the copper-silver-zinc alloy inner ring and the inner wall of the GH600 high-temperature alloy outer ring; S2. Assemble the GH600 high temperature alloy outer ring, the silver-based alloy middle layer and the copper-silver-zinc alloy inner ring and place them in the package, vacuum seal and weld them, and perform hot isostatic pressing; S3. Raise the temperature to 670-700°C, the pressure to 160-180 MPa, and keep warm for 40-70 minutes; S4. Cooling under pressure, venting and depressurizing after cooling to below 150°C, and removing the jacket to obtain GH600 high temperature alloy and copper-silver-zinc alloy formed parts.

2. The diffusion bonding method of GH600 high temperature alloy and copper-silver-zinc alloy according to claim 1, characterized in that: The thickness of the silver-based alloy intermediate layer is 0.1-0.15 mm.

3. The diffusion bonding method of GH600 high temperature alloy and copper-silver-zinc alloy according to claim 1, characterized in that: The silver-based alloy intermediate layer is made of BAg49CuZnMnNi material.

4. The diffusion bonding method of GH600 high temperature alloy and copper-silver-zinc alloy according to claim 1, characterized in that: The heating process includes: firstly heating to 300-400°C with a pressure not less than 100MPa, and then heating to 670-700°C with a pressure of 160-180MPa.

5. The diffusion bonding method of GH600 high temperature alloy and copper-silver-zinc alloy according to claim 1, characterized in that: The temperature is raised to 680-690° C. and the pressure is 165-175 MPa.

6. The diffusion bonding method of GH600 high temperature alloy and copper-silver-zinc alloy according to claim 5, characterized in that: The temperature is raised to 685°C and the pressure is 170MPa.

7. The diffusion bonding method of GH600 high temperature alloy and copper-silver-zinc alloy according to claim 1, characterized in that: The heating rate is 4-6°C / min.

8. The diffusion bonding method of GH600 high temperature alloy and copper-silver-zinc alloy according to claim 1, characterized in that: The cooling rate is 1.5-2.5°C / min.

9. The diffusion bonding method of GH600 high temperature alloy and copper-silver-zinc alloy according to claim 1, characterized in that: The contact surface of the copper-silver-zinc alloy inner ring or the GH600 high-temperature alloy outer ring is an uneven surface.

10. The diffusion bonding method of GH600 high temperature alloy and copper-silver-zinc alloy according to claim 9, characterized in that: The uneven surface includes a comb tooth surface, a thread surface or a step surface.

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