High-strength gold-based alloy brazing filler metal and preparation method and application thereof

Abstract

The invention discloses high-strength gold-based alloy brazing filler metal and a preparation method and application thereof, and belongs to the technical field of alloy brazing. The brazing filler metal comprises the following components in percentage by mass: 0.5 to 5.0 percent of Ni, 0 to 10.0 percent of Cu, 0 to 2.0 percent of Ag, 0.1 to 1.0 percent of Pd and the balance of Au. Pd and Ag are added into the brazing filler metal, the brazing filler metal is applied to brazing of the base metal of the nickel-based superalloy containing Cr or / and Mo, the bonding strength of a welding joint of a nickel-based superalloy component and the oxidation resistance of the joint can be effectively improved, and therefore the brazing can play a more sufficient effect in brazing of the nickel-based superalloy, and the welding quality of the nickel-based superalloy component is improved. And the performance of a welding joint of the nickel-based high-temperature alloy component is improved, so that the normal operation time of the nickel-based high-temperature alloy component under extreme working conditions is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy brazing, and relates to a high-strength gold-based alloy brazing material and a preparation method and application thereof. Background Art

[0002] GH4169 alloy (Inconel 718) is a typical nickel-based high-temperature alloy containing Cr and Mo, which is widely used in aerospace, gas turbines, nuclear power and other high-temperature and high-pressure fields. These application scenarios put forward strict requirements on the material to have high strength, oxidation resistance and excellent thermal stability in extreme environments. In order to ensure the long-term stable operation of nickel-based high-temperature alloys under extreme working conditions, connection methods such as fusion welding, diffusion welding and brazing are usually used to make related components. Among them, brazing is more used in welding nickel-based high-temperature alloys because of its low heat input, which is especially suitable for the connection of complex structures and dissimilar materials. Compared with other connection methods, brazing can effectively reduce the organizational changes of the parent material and maintain the high-temperature performance of nickel-based high-temperature alloys. In addition, the brazing process has high flexibility and can be carried out under vacuum or protective atmosphere conditions, which significantly improves the oxidation resistance of the brazed joint and extends its service life.

[0003] In the actual welding process of brazing, AuCuNi (gold-based) brazing filler metals (such as American grades BAu-2, BAu-4, British grades Au1, Au2, etc.) are widely used brazing filler metals. However, since nickel-based high-temperature alloys contain elements such as nickel (Ni), chromium (Cr), and molybdenum (Mo), these elements react with Ni in the brazing filler metal during the brazing process to form hard and brittle intermetallic compounds (such as Ni-Cr compounds and Ni-Mo compounds) at the interface between the weld and the base material. These compounds can easily become crack sources, leading to brittle fracture of the welded joint, especially when subjected to thermal stress or mechanical stress. This phenomenon is more significant. In addition, the oxidation resistance of traditional AuCuNi brazing filler metals under high-temperature service conditions is not as good as that of nickel-based high-temperature alloy matrix materials. The welded joints are prone to oxidation, which leads to a decrease in joint strength and gradual degradation of weld performance. These problems seriously threaten the stability of the welded joints of nickel-based high-temperature alloy structural parts in high-temperature service, and may lead to premature failure of the structural parts.

[0004] Therefore, it is necessary to provide a high-strength gold-based brazing filler metal and its preparation method and application to improve the bonding strength of the brazed joint, optimize the oxidation resistance of the welded joint, use the brazing filler metal in the brazing of nickel-based high-temperature alloys containing Cr and / or Mo, improve the brazing performance of nickel-based high-temperature alloys, and further improve the strength and thermal stability of nickel-based high-temperature alloy components under extreme working conditions, and ensure the reliable operation of nickel-based high-temperature alloys under extreme service conditions. Summary of the invention

[0005] In order to overcome the problems in the background technology, the present invention significantly promotes the mutual diffusion of Ni, Cu in the brazing filler metal and Ni, Cr and other elements in the parent material by adding Pd to the brazing filler metal, reduces the thermodynamic stability of the brittle hard phase compound, and reduces its precipitation amount at the interface, thereby improving the bonding strength of the brazed joint. At the same time, Pd can generate a dense PdO protective layer, effectively blocking oxygen penetration, helping to prevent the weld from being oxidized, and strengthening the oxidation resistance of the welded joint.

[0006] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0007] On one hand, the present invention provides a high-strength gold-based alloy solder, which comprises the following components by mass fraction: Ni: 0.5-5.0%, Cu: 0-10.0%, Ag: 0-2.0%, Pd: 0.1-1.0%, and the balance is Au.

[0008] Preferably, the solder comprises the following components by mass fraction: Ni: 3.0%, Cu: 6.0%, Ag: 0.50%, Pd: 0.5%, and the remainder is Au.

[0009] Preferably, the solder comprises the following components by mass fraction: Ni: 3.0%, Cu: 6.0%, Ag: 1.0%, Pd: 0.5%, and the remainder is Au.

[0010] Preferably, the solder comprises the following components by mass fraction: Ni: 3.0%, Cu: 6.0%, Ag: 1.0%, Pd: 1.0%, and the remainder is Au.

[0011] Another aspect of the present invention provides a method for preparing the above solder, the preparation method comprising the following steps:

[0012] (1) Melting: Melting the raw material element under vacuum conditions to obtain alloy solder;

[0013] (2) rolling: cold rolling the alloy solder in step (1);

[0014] (3) Surface treatment is performed on the alloy solder after cold rolling in the step (2) to obtain a high-strength gold-based alloy solder.

[0015] Preferably, in step (1), the vacuum degree of the vacuum condition is ≤6×10 -3 Pa.

[0016] Preferably, in step (1), the smelting temperature is 1000-1200° C. and the smelting time is 30-60 min.

[0017] Preferably, in step (2), the total cold rolling deformation is 80%, and during the rolling process, the deformation of each pass is controlled at 5% to 15%, and the thickness of the alloy solder after rolling is 0.1 to 0.5 mm.

[0018] Preferably, in step (3), the surface of the alloy solder is polished with sandpaper and then cleaned with acetone to obtain a high-strength gold-based alloy solder.

[0019] The invention also proposes the application of the brazing material in brazing of nickel-based high-temperature alloys containing Cr and / or Mo.

[0020] Preferably, the nickel-based high-temperature alloy is GH4169.

[0021] GH4169 base material vacuum brazing includes the following steps:

[0022] S1: Surface treatment of GH4169 base material to remove surface grease and dirt;

[0023] S2: Assemble the GH4169 base material according to the designed lap joint method;

[0024] S3: vacuum brazing the GH4169 base material using the gold-based alloy brazing filler metal to obtain a brazed component.

[0025] Preferably, in step S1, an organic solvent is used to clean the surface of the GH4169 base material.

[0026] Preferably, in step S2, after assembly, the weld width is 0.01-0.04 mm.

[0027] Preferably, in step S3, the vacuum degree of vacuum brazing is ≤6×10 -3 Pa, first raise the temperature to 950℃ at a heating rate of 10℃ / min, keep it warm for 10min, then continue to raise the temperature to 1000~1050℃ at a heating rate of 10℃ / min, keep it warm for 4~20min, and then the brazed components are cooled to room temperature with the furnace.

[0028] The vacuum brazing method of other nickel-based high-temperature alloys containing Cr and / or Mo is similar to the above method.

[0029] Beneficial effects of the present invention:

[0030] 1. The present invention promotes the mutual diffusion of Ni, Cu in the solder and Ni, Cr and other elements in the base material by adding Pd to the solder, reduces the precipitation of Ni-Cr and Ni-Mo compounds at the interface, and effectively improves the bonding strength of the welded joint.

[0031] 2. The present invention adds Pd to the solder to form a dense PdO layer during high-temperature oxidation, which effectively blocks oxygen diffusion, helps prevent weld oxidation, and improves the oxidation resistance of the welded joint.

[0032] 3. The present invention adds Ag to the solder and utilizes the characteristics of Ag's low melting point, infinite solid solution with Au, and high diffusion rate to help the solder form a liquid phase at a lower temperature, improve the fluidity of the molten pool, thereby reducing weld porosity and loose connection defects, and further strengthening the bonding strength of the welded joint.

[0033] 4. By using the brazing filler metal of the present invention to weld nickel-based high-temperature alloy parent materials containing Cr and / or Mo, the negative impact of traditional brazing fillers on welded joints is compensated, so that the brazing effect is more fully exerted, and the welded joints of nickel-based high-temperature alloy components have more excellent bonding strength and oxidation resistance, so that the nickel-based high-temperature alloy has a longer service life under extreme working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The microscopic morphology of the GH4169 alloy brazed joints, wherein (a) is a microscopic morphology of the joint after being welded using the brazing filler metal of Comparative Example 1, and (b) is a microscopic morphology of the joint after being welded using the brazing filler metal of Example 2;

[0035] Figure 2 The spreading area of ​​the solder prepared in Examples 1-3 of the present invention and Comparative Example 1 on the GH4169 alloy;

[0036] Figure 3 The tensile strength of GH4169 alloy joints brazed with the solders prepared in Examples 1-3 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below in conjunction with specific embodiments.

[0038] In the examples and comparative examples of the present invention, chemical reagents not otherwise specified were all commercially available analytically pure reagents for the experiments.

[0039] In the embodiments of the present invention and comparative examples, the solder components are as shown in Table 1.

[0040] Table 1

[0041]

[0042] Example 1

[0043] In this embodiment, the brazing filler metal is prepared as follows, and the prepared brazing filler metal is used for brazing GH4169 base material:

[0044] (1) The gold-based alloy solder composition in Table 1 was prepared and 20 g of raw materials were weighed, wherein the raw material purity was above 99.99%.

[0045] (2) Place the ingredients in a vacuum induction furnace, and after the vacuum reaches below 6×10-3Pa, heat to 1000℃ and smelt for 60min to fully melt all the metals to form a uniform alloy melt. After smelting, the alloy is cooled to room temperature in the furnace.

[0046] (3) The smelted alloy solder is rolled to a thickness of 0.2 mm using a cold rolling process.

[0047] (4) The surface of the alloy solder is polished with sandpaper and cleaned with acetone to obtain a clean sample. The solder prepared in this example is denoted as: AuCu6Ni3Ag0.5Pd0.5.

[0048] (5) Use organic solvents (such as acetone or alcohol) to treat the surface of GH4169 base material to remove grease and dirt on the surface.

[0049] (6) Assemble the GH4169 base material in lap joint mode, and control the weld width to 0.01-0.04 mm;

[0050] (7) Place the brazing sample in a vacuum brazing furnace and start heating when the vacuum degree drops below 6×10-3Pa. Raise the temperature to 950℃ at a rate of 10℃ / min. Keep it at that temperature for 10 minutes and then continue to raise the temperature to 1000℃ at the same rate. Keep it at that temperature for 20 minutes and then cool it to room temperature in the furnace.

[0051] The spreading area of ​​the solder on the GH4169 alloy in this embodiment was tested, and the results were as follows: Figure 2 shown.

[0052] In this embodiment, the tensile strength test of the welded joint of the GH4169 component after brazing is carried out. The results are as follows: Figure 3 shown.

[0053] Example 2

[0054] In this embodiment, the brazing filler metal is prepared as follows, and the prepared brazing filler metal is used for brazing GH4169 base material:

[0055] (1) The gold-based alloy solder composition in Table 1 was prepared and 20 g of raw materials were weighed, wherein the raw material purity was above 99.99%.

[0056] (2) Place the ingredients in a vacuum induction furnace, and after the vacuum reaches below 6×10-3Pa, heat to 1100℃ and smelt for 45min to fully melt all the metals to form a uniform alloy melt. After smelting, the alloy is cooled to room temperature in the furnace.

[0057] (3) The smelted alloy solder is rolled to a thickness of 0.1 mm using a cold rolling process.

[0058] (4) The surface of the alloy solder is polished with sandpaper and cleaned with acetone to obtain a clean sample. The solder prepared in this example is denoted as: AuCu6Ni3Ag1.0Pd0.5.

[0059] (5) Use organic solvents (such as acetone or alcohol) to treat the surface of GH4169 base material to remove grease and dirt on the surface.

[0060] (6) Assemble the GH4169 base material in lap joint mode, and control the weld width to 0.01-0.04 mm;

[0061] (7) Place the brazing sample in a vacuum brazing furnace and start heating when the vacuum degree drops below 6×10-3Pa. Raise the temperature to 950℃ at a rate of 10℃ / min. Keep it at that temperature for 10 minutes and then continue to raise the temperature to 1030℃ at the same rate. Keep it at that temperature for 10 minutes and then cool it to room temperature in the furnace.

[0062] The microstructure test of the welded joint of the GH4169 component after brazing in this embodiment is as follows: Figure 1 shown.

[0063] The spreading area of ​​the solder on the GH4169 alloy in this embodiment was tested, and the results were as follows: Figure 2 shown.

[0064] In this embodiment, the tensile strength test of the welded joint of the GH4169 component after brazing is carried out. The results are as follows: Figure 3 shown.

[0065] Example 3

[0066] In this embodiment, the brazing filler metal is prepared as follows, and the prepared brazing filler metal is used for brazing GH4169 base material:

[0067] (1) The gold-based alloy solder composition in Table 1 was prepared and 20 g of raw materials were weighed, wherein the raw material purity was above 99.99%.

[0068] (2) Place the ingredients in a vacuum induction furnace, and after the vacuum reaches below 6×10-3Pa, heat to 1200℃ and smelt for 30min to fully melt all the metals to form a uniform alloy melt. After smelting, the alloy is cooled to room temperature in the furnace.

[0069] (3) The smelted alloy solder is rolled to a thickness of 0.5 mm using a cold rolling process.

[0070] (4) The surface of the alloy solder is polished with sandpaper and cleaned with acetone to obtain a clean sample. The solder prepared in this example is denoted as: AuCu6Ni3Ag1.0Pd1.0.

[0071] (5) Use organic solvents (such as acetone or alcohol) to treat the surface of GH4169 base material to remove grease and dirt on the surface.

[0072] (6) Assemble the GH4169 base material in lap joint mode, and control the weld width to 0.01-0.04 mm;

[0073] (7) Place the brazing sample in a vacuum brazing furnace and start heating when the vacuum degree drops below 6×10-3Pa. Raise the temperature to 950℃ at a rate of 10℃ / min. Keep it at that temperature for 10 minutes and then continue to raise the temperature to 1050℃ at the same rate. Keep it at that temperature for 4 minutes and then cool it to room temperature in the furnace.

[0074] The spreading area of ​​the solder on the GH4169 alloy in this embodiment was tested, and the results were as follows: Figure 2 shown.

[0075] In this embodiment, the tensile strength test of the welded joint of the GH4169 component after brazing is carried out. The results are as follows: Figure 3 shown.

[0076] Example 4

[0077] This embodiment adopts the same method as that of Embodiment 1 for preparing the brazing filler metal and brazing the GH4169 base material. The brazing filler metal and GH4169 component prepared in this embodiment have similar performance to those of the brazing filler metal and component in Embodiment 1.

[0078] Example 5

[0079] This embodiment adopts the same method as that of Embodiment 1 for preparing the brazing filler metal and brazing the GH4169 base material. The brazing filler metal and GH4169 component prepared in this embodiment have similar performance to those of the brazing filler metal and component in Embodiment 1.

[0080] Comparative Example 1

[0081] This comparative example adopts the same method as Example 2 for preparing the solder and brazing the GH4169 base material.

[0082] The microstructure test of the welded joint of the GH4169 component after brazing in this embodiment is as follows: Figure 1 shown.

[0083] The spreading area of ​​the solder on the GH4169 alloy in this embodiment was tested, and the results were as follows: Figure 2 shown.

[0084] In this embodiment, the tensile strength test of the welded joint of the GH4169 component after brazing is carried out. The results are as follows: Figure 3 shown.

[0085] Comparative Example 2

[0086] This comparative example adopts the same method as Example 2 for preparing the solder and brazing the GH4169 base material.

[0087] The bonding strength of the GH4169 component welded joint after brazing in this comparative example is poor. Excessive Ag content in the brazing filler metal will lead to premature liquefaction of the molten pool, narrow the operating temperature window, and increase the fluidity of the melt, thus causing uneven weld formation and defects such as pores and shrinkage holes; although excessive Pd improves the oxidation resistance, the PdO layer formed at high temperature will hinder the mutual diffusion of interface elements, weakening the metallurgical bonding strength and the stability of the weld.

[0088] pass Figure 2 , Figure 3 The quantitative results of solder spreading area and tensile strength can be obtained, as shown in Table 2.

[0089] Table 2

[0090]

[0091] It can be seen from Table 1 that in Examples 1-3, the solder spreading area and the tensile strength of the GH4169 component welded joints are better than those in Comparative Example 1, which fully demonstrates that by adding Ag and Pd to the solder, the solder spreading area on the surface of the GH4169 base material can be increased, and its spreading area increases with the increase of the Ag content in the alloy, indicating that the addition of Ag and Pd can improve the wettability and fluidity of the solder. More importantly, in Comparative Example 1, the tensile strength of the component welded joints decreased significantly under high temperature conditions, while the solder of Example 2 showed higher tensile strength and excellent thermal stability in the range of 450°C to 850°C. Especially at high temperatures of 650°C and 850°C, the tensile strength of the solder in Example 2 is significantly better than other formulations, which fully verifies its advantages in high temperature mechanical properties and thermal stability.

[0092] pass Figure 1 It can be seen that the comparative example 1 ( Figure 1(a)) The interface structure of the brazed joint of the components is discontinuous and crack-like, showing obvious pores and uneven bonding areas, indicating that the brazing material in Comparative Example 1 has poor bonding at the interface and is prone to form a hard and brittle phase during use, thereby weakening the overall strength and stability of the joint. In contrast, Example 2 ( Figure 1 (b) The interface of the brazed joint of the components presents a uniform and dense bonding structure, with a clear interface and no obvious cracks or pores. This shows that the addition of Ag and Pd significantly improves the fluidity and wettability of the brazing filler metal, promotes the mutual diffusion of elements between the brazing filler metal and the GH4169 alloy, inhibits the precipitation of hard and brittle compounds at the interface, and significantly enhances the firmness and uniformity of the interface bonding.

[0093] In summary, the present invention can promote the mutual diffusion of Ni, Cu in the brazing filler metal with Ni, Cr and other elements in the parent metal by adding Pd and Ag to the brazing filler metal, reduce the precipitation of interface compounds, and effectively improve the strength of the component welding joint and the brazing filler metal spreading area after brazing with the brazing filler metal of the present invention, especially for alloys with high Ni and Cr contents such as GH4169, the effect is more prominent.

[0094] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A high-strength gold-based alloy solder, characterized in that: The solder comprises the following components by mass fraction: Ni: 0.5-5.0%, Cu: 0-10.0%, Ag: 0-2.0%, Pd: 0.1-1.0%, and the balance is Au.

2. The method for preparing a high-strength gold-based alloy solder according to claim 1, characterized in that: The preparation method comprises the following steps: (1) Melting: Melting the raw material element under vacuum conditions to obtain alloy solder; (2) rolling: cold rolling the alloy solder in step (1); (3) Surface treatment is performed on the alloy solder after cold rolling in the step (2) to obtain a high-strength gold-based alloy solder.

3. The preparation method according to claim 2, characterized in that: In the step (1), the vacuum degree of the vacuum condition is ≤6×10 -3 Pa.

4. The preparation method according to claim 2, characterized in that: In the step (1), the smelting temperature is 1000-1200° C. and the smelting time is 30-60 min.

5. The preparation method according to claim 2, characterized in that: In the step (2), the total cold rolling deformation is 80%, and during the rolling process, the deformation of each pass is controlled at 5% to 15%, and the thickness of the alloy solder after rolling is 0.1 to 0.5 mm.

6. The preparation method according to claim 2, characterized in that: In the step (3), the surface of the alloy solder is polished with sandpaper and then cleaned with acetone to obtain a high-strength gold-based alloy solder.

7. Application of the high-strength gold-based alloy brazing filler metal according to claim 1 in brazing of nickel-based high-temperature alloys containing Cr and / or Mo.

8. The use according to claim 7, characterized in that: The nickel-based high-temperature alloy is GH4169.

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