Novel strengthening and toughening nickel-based brazing filler metal with large joint filling capacity

Abstract

The invention provides a novel strengthening and toughening nickel-based brazing filler metal with high joint filling capacity. The novel strengthening and toughening nickel-based brazing filler metal is prepared from the following components in percentage by mass: 3.5 to 4.0 percent of boron, 4.0 to 5.0 percent of silicon, 3.5 to 4.0 percent of titanium, 10.0 to 12.0 percent of chromium, 0 to 1.0 percent of cobalt, 3.0 to 5.0 percent of iron and the balance of nickel. The strengthening and toughening novel nickel-based brazing filler metal with the large joint filling capacity has the good wettability and the good joint filling capacity at the same time and is suitable for use requirements of specific working conditions, and a brazed joint formed through brazed connection of the brazing filler metal has the good room-temperature tensile strength.

Description

Technical Field

[0001] The present invention relates to the technical field of nickel-based superalloy brazing, and more specifically, to a new type of nickel-based filler metal with strong gap filling ability and toughness. Background Art

[0002] The fuel nozzle is a key component of the aero-engine combustion chamber. Fuel is constrained by the nozzle flow passage under high pressure, sprayed in a certain velocity and atomized form, and mixed with compressed air in a certain proportion for combustion to form the working source of the engine. In the manufacturing process of aero-engine fuel nozzles, welding is a crucial step. Welding has advantages such as improving structural strength, corrosion resistance, and manufacturing efficiency, and plays a decisive role in the quality and reliability of key components.

[0003] Brazing is a welding method that uses a filler metal with a melting point lower than that of the base metal. Without melting the base metal, the filler metal is melted to fill the joint gap and diffuses with the base metal to achieve connection.

[0004] With the development of aero-engine technology in China, the structure of the engine fuel nozzle is becoming more and more complex. In the multiple brazing of the nozzle structure, one step of brazing involves the combined brazing of a total of 6 parts, namely the rear cover plate, the main nozzle, the nozzle housing, the adapter pipe, the primary swirler, and the secondary nozzle assembly. One end of the 4Cr13 adapter pipe forms a sealed brazing weld with the 4Cr13 main nozzle and the additively manufactured GH3536 alloy nozzle housing respectively, and the other end forms a sealed brazing weld with the 4Cr13 primary swirler and the 4Cr13 secondary nozzle assembly respectively, constituting a multi-layer closed space brazing structure. After assembly, the brazing weld between the secondary oil passage of the housing and the main nozzle is hidden inside, and the filler metal cannot be directly added. The filler metal cannot reach, and the filler metal can only be added at the contact between the inside of the main nozzle and the adapter pipe. After melting, it wets and spreads through the first layer to reach the second layer to achieve the sealing of the second layer. It is necessary to solve the contradiction between the wettability of the filler metal and the gap filling ability and ensure the sealing requirements of multiple brazing. Summary of the Invention

[0005] (1) Technical Problems to be Solved

[0006] The technical problem to be solved by the present invention is the contradiction between the wettability of the filler metal and the gap filling ability, and ensure the sealing requirements of multiple brazing.

[0007] (2) Technical Solutions

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] Provide a new type of nickel-based filler metal with strong gap filling ability and toughness, including the following components by mass percentage: 3.5 - 4.0% boron, 4.0 - 5.0% silicon, 3.5 - 4.0% titanium, 10.0 - 12.0% chromium, 0 - 1.0% cobalt, 3.0 - 5.0% iron, and the balance nickel.

[0010] Preferably, the melting temperature of the novel nickel-based brazing filler metal with strong large-gap filling ability is 950°C to 1020°C.

[0011] Preferably, the working temperature range of the novel nickel-based brazing filler metal with strong large-gap filling ability is 550 - 600°C.

[0012] Preferably, the novel nickel-based brazing filler metal with strong large-gap filling ability is prepared by the following steps:

[0013] S1. Weigh each component raw material according to a predetermined mass percentage;

[0014] S2. Melting each component raw material under a vacuum state to obtain liquid metal;

[0015] S3. Inhale the liquid metal into an atomizer, and under the atmosphere of a protective gas, atomize to obtain fine metal droplets, and the metal droplets are rapidly cooled and solidified into powder to obtain the novel nickel-based brazing filler metal with strong large-gap filling ability.

[0016] Preferably, the following steps are further included:

[0017] S4. Screen and collect the powder with a mesh size below 180 meshes using a 180-mesh sieve.

[0018] Preferably, after step S1, the following steps are further included:

[0019] After polishing the surface scale and impurities of each component raw material with sandpaper, ultrasonically clean it with an acetone solution for 15 minutes, then ultrasonically clean it with an ethanol solution for 5 minutes, and dry it at a temperature of 60°C.

[0020] Preferably, step S2 includes the following steps;

[0021] Melting each component raw material under a vacuum state;

[0022] In a protective gas environment, keep it at a temperature of 1550°C for 40 minutes to obtain liquid metal.

[0023] Preferably, in step S3, the atomization pressure is 5 MPa to 7.5 MPa, and the gas flow rate is 10 - 12 m 3 / min.

[0024] (III) Beneficial effects

[0025] The above technical solutions of the present invention have at least the following advantages:

[0026] In the present invention, the novel nickel-based brazing filler metal with strong large-gap filling ability provided by the present invention has good wettability and gap filling ability at the same time, is suitable for the use requirements of specific working conditions, and the brazed joint formed by brazing has good room temperature tensile strength.

[0027] The present invention uses a vacuum smelting - atomization powder preparation method to realize the preparation of a new type of nickel - based brazing filler metal with strong gap - filling ability and toughness. The prepared powder has the advantages of fine particle size, high sphericity, low oxygen content, high efficiency and low cost. Brief Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 is a schematic structural diagram of an aero - engine fuel nozzle provided by an embodiment of the present invention.

[0030] Figure 2 is a metallographic diagram of a 4Cr13 stainless steel brazed joint provided by an embodiment of the present invention.

[0031] Figure 3 is a metallographic diagram of a GH3536 brazed joint provided by an embodiment of the present invention.

[0032] The reference numerals in the drawings are as follows:

[0033] 1, main nozzle; 2, auxiliary nozzle; 3, swivel pipe; 4, primary swirler; 5, rear cover plate; 6, nozzle housing. Detailed Embodiments

[0034] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the following further details the present application in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0035] It should be understood that in various embodiments of the present application, the magnitude of the serial numbers of the above - mentioned processes does not mean the order of execution. Some or all steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0036] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms of "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0037] In the description of the embodiments of the present application, the weights of the relevant components not only can refer to the specific contents of each component, but also can represent the proportional relationships of the weights between the components. Therefore, as long as the contents of the relevant components in the description of the embodiments of the present application are enlarged or reduced proportionally, they are within the scope disclosed in the description of the embodiments of the present application. Specifically, the mass described in the description of the embodiments of the present application can be mass units well-known in the chemical industry such as μg, mg, g, kg, etc.

[0038] An embodiment of the present invention provides a novel nickel-based brazing filler metal with strong gap filling ability and toughness, which includes the following components by mass percentage: 3.5-4.0% boron, 4.0-5.0% silicon, 3.5-4.0% titanium, 10.0-12.0% chromium, 0-1.0% cobalt, 3.0-5.0% iron, and the balance nickel.

[0039] In this embodiment, titanium elements can improve the wettability and spreadability of the brazing filler metal, and chromium, cobalt, and iron elements are subjected to solid solution strengthening to improve the strength of the brazed joint and the gap filling ability of the brazing filler metal. Boron and silicon elements are melting point lowering elements and can improve the wettability and fluidity of the brazing filler metal. Through the ratio of the above components, the preparation of a nickel-based brazing filler metal with strong gap filling ability, toughness, and high wettability can be achieved.

[0040] In one embodiment, the melting temperature of the novel nickel-based brazing filler metal with strong gap filling ability and toughness is 950°C to 1020°C.

[0041] In one embodiment, the working temperature range of the novel nickel-based brazing filler metal with strong gap filling ability and toughness is 550-600°C. Specifically, when the novel nickel-based brazing filler metal with strong gap filling ability and toughness is within this working temperature range, it can maintain certain metal properties.

[0042] In one embodiment, the novel nickel-based brazing filler metal with strong gap filling ability and toughness is prepared by the following steps:

[0043] S1. Weigh the raw materials of each component according to the predetermined mass percentage; specifically, weigh the metal raw materials of nickel, boron, silicon, titanium, chromium, cobalt, and iron according to the predetermined mass percentage. After polishing the surface oxide scale and impurities of the corresponding pure metal raw materials with sandpaper, first ultrasonically clean them in an acetone solution for about 15 minutes, then ultrasonically clean them in an ethanol solution for about 5 minutes, and dry them at 60°C.

[0044] S2. Melt the raw materials of each component under a vacuum state to obtain liquid metal; specifically, melt the raw materials of nickel, boron, silicon, titanium, chromium, cobalt, and iron under a vacuum state, protect with argon, keep warm at 1550°C for 40 minutes, and obtain liquid metal.

[0045] S3. Inhale the liquid metal into the atomizer. Under the atmosphere of protective gas, atomize it to obtain fine metal droplets. The metal droplets are rapidly cooled and solidified into powder to obtain the nickel-based filler metal. Specifically, pour the liquid metal into the tundish. Under the protection of nitrogen and atmosphere, inhale the liquid metal into the atomizer. The atomization pressure is 5 MPa to 7.5 MPa, and the gas flow rate is 10 - 12 m 3 / min. Atomize to obtain fine metal droplets, which are rapidly cooled and solidified into powder. Collect the powder to obtain the novel nickel-based filler metal with strong large-gap filling ability and toughness. Further, adopt the vacuum smelting-atomization powder preparation method to prepare the novel nickel-based filler metal with strong large-gap filling ability and toughness. The prepared powder has the advantages of fine particle size, high sphericity, low oxygen content, high efficiency and low cost.

[0046] S4. Use a 180-mesh sieve to screen and collect the powder below 180 mesh. Specifically, use a 180-mesh sieve to screen and collect the powder below 180 mesh from the obtained powder.

[0047] It should be noted that in this embodiment, the content of impurities needs to be strictly controlled during the preparation of the novel nickel-based filler metal with strong large-gap filling ability. Excessive impurities will affect the wettability and gap filling ability of the filler metal. Before preparation, check the crucible and equipment conditions. The crucible can be loaded only when it is in good condition; the furnace charge must be kept dry without oil, mud, moisture, etc.; each ladle needs to be preheated and the slag removed, which can greatly reduce the impurities in the filler metal. Specifically, the total amount of impurity elements needs to be controlled to be less than 0.3%.

[0048] The following elaborates on the solution of the present application in combination with specific embodiments:

[0049] Example 1

[0050] Prepare the novel nickel-based filler metal with strong large-gap filling ability according to the component ratio and preparation steps in the above embodiment. Among them, the measured novel nickel-based filler metal (filler metal powder) includes the following components by mass percentage: the balance is nickel, 3.77% of boron, 4.36% of silicon, 3.80% of titanium, 10.75% of chromium, 0.42% of cobalt, 3.41% of iron, and 0.17% of impurities. Take the filler metal powder and add industrial white oil and a high molecular polymer with a molecular weight of 200 - 3000 to make the soldering paste. The measured melting temperature range of the novel nickel-based filler metal with strong large-gap filling ability is 977 °C to 1032 °C.

[0051] Such as Figure 1The shown aero-engine fuel nozzle mainly comprises: a main nozzle 1, a sub-nozzle 2, a swivel pipe 3, a primary swirler 4, a rear cover plate 5, and a nozzle housing 6; wherein, the main nozzle 1 and the sub-nozzle 2 are installed inside the nozzle housing 6, the sub-nozzle 2 is assembled and fixed inside the main nozzle 1, the primary swirler 4 is assembled on the outer peripheral side of the sub-nozzle 2, a first sub-oil passage hole is provided on the main nozzle 1, a second sub-oil passage hole is provided on the sub-nozzle 2, the swivel pipe 3 penetrates through the first sub-oil passage hole and the second sub-oil passage hole to connect the first sub-oil passage hole and the second sub-oil passage hole, and the rear cover plate 5 is connected to the rear part of the sub-nozzle 2.

[0052] Currently, the brazing process of this aero-engine fuel nozzle is as follows:

[0053] The weld position 924 to be brazed is as Figure 1 shown. First, the sub-nozzle 2 is inserted into the main nozzle 1, and the first sub-oil passage hole and the second sub-oil passage hole are aligned. After alignment, the swivel pipe 3 is inserted into the first sub-oil passage hole to position and fix the sub-nozzle 2 and the main nozzle 1. During the assembly process, the axial positioning of each component is determined by a tooling, and the angular positioning of each component is achieved through the connection between the boss on the main nozzle 1 and the groove on the nozzle housing 6. When brazing among the main nozzle 1, the sub-nozzle 2, and the swivel pipe 3, the filler metal can only be filled at Figure 1 the position A (the contact position between the inside of the main nozzle and the swivel pipe) shown, and the filler metal at position A is heated during the brazing process to make the filler metal have a certain fluidity, so that it can fill into the circumferential welding surface of the swivel pipe 3 (i.e., Figure 1 the position B shown in), to achieve the brazing connection between the swivel pipe 3, the main nozzle 1, the sub-nozzle 2, and the primary swirler 4.

[0054] In the prior art, there is a filler metal with good gap filling ability, which can ensure complete filling of the weld area, but its wettability is poor, that is, it does not have good fluidity after heating, and the weld at position B cannot be filled in this working condition, so it is not applicable to this working condition; in the prior art, there is also a filler metal with good wettability, which has good fluidity after heating and can flow from position A to position B, but its gap filling ability is poor, and finally, the brazed joint is prone to defects such as holes and gaps, which will affect the mechanical properties of the joint, and it is also not applicable to this working condition. Therefore, based on this working condition, it is necessary to solve the contradiction between the wettability and the gap filling ability of the filler metal to ensure the sealing requirements of multiple brazings. Based on this, this embodiment provides a new type of nickel-based filler metal with strong gap filling ability and toughness to solve the above technical problems.

[0055] After actual tests, using a new type of nickel-based filler metal with strong gap filling ability and toughness provided by this embodiment for such as Figure 1During the brazing of the shown aero-engine fuel nozzle, the filler metal filled at position A can smoothly flow to position B during the brazing process, effectively filling the weld at position B. The finally prepared brazed joint of the aero-engine fuel nozzle has no obvious welding defects, its mechanical properties meet the usage requirements, and it meets the sealing requirements of this part.

[0056] The brazing test of the aero-engine fuel nozzle was carried out using this new nickel-based filler metal with strong large-gap filling ability and toughening:

[0057] Based on the brazing working conditions of the above aero-engine fuel nozzle, among them, the main nozzle 1, the auxiliary nozzle 2, the swivel pipe 3 and the first-stage swirler 4 are generally preferably additively manufactured with 4Cr13 stainless steel material, and the nozzle housing 6 is preferably additively manufactured with GH3536 material. To further study the mechanical properties of the brazed joint prepared by this new nickel-based filler metal with strong large-gap filling ability and toughening, in this embodiment, test pieces were prepared from two materials and tensile tests were carried out. The specific process is as follows:

[0058] First, prepare the additively manufactured GH3536 test piece and the 4Cr13 test piece. Take an appropriate amount of the nickel-based brazing paste prepared by the above new nickel-based filler metal with strong large-gap filling ability and toughening, and uniformly pre-place it at the welding position. Then place the test piece on a special fixture. Place the test piece with the pre-placed filler metal in a vacuum brazing furnace, evacuate to below 5×10 -4 Pa, heat it at a rate of 10 - 20 °C / min to 550 °C, hold for 15 min, then heat it at a rate of 10 - 20 °C / min to 940 °C, hold for 20 min, and finally heat it at a rate of 5 °C / min to 1050 °C, hold for 120 min. After welding, quickly cool it to below 100 °C by filling argon and then take it out.

[0059] Cutting the test piece shows that the filler metal is evenly and continuously distributed, there is no lack of welding, the welding is good, and the multi-layer closed space structure brazing of the aero-engine fuel nozzle is realized; the metallographic analysis of the brazed joint of 4Cr13 is as Figure 2 shown. The brazing interface is dense, and the joint structure is white γ solid solution distributed with dot-like borides and carbides. The measured room-temperature tensile strength of the brazed joint reaches 484 MPa; the metallographic analysis of the brazed joint of GH3536 is as Figure 3 shown. The brazing interface is dense, and the joint structure is white γ solid solution distributed with dot-like borides and carbides. The measured room-temperature tensile strength of the brazed joint reaches 650 MPa.

[0060] In the prior art, BNi82CrSiB filler metal is generally used for brazing the fuel nozzle of an aeroengine; compared with the prior art, for the 4Cr13 stainless steel joint brazed with BNi82CrSiB filler metal, its room temperature tensile strength is 320 MPa. For the 4Cr13 stainless steel joint brazed with the novel nickel-based filler metal with strong large-gap filling ability and toughening provided in this embodiment, its room temperature tensile strength is increased to 484 MPa. For the GH3536 joint brazed with BNi82CrSiB filler metal, its room temperature tensile strength is 380 MPa. For the GH3536 joint brazed with the novel nickel-based filler metal with strong large-gap filling ability and toughening provided in this embodiment, its room temperature tensile strength is increased to 650 MPa. Thus, it can be seen that the brazing with the novel nickel-based filler metal with strong large-gap filling ability and toughening in this test example has the ability to toughen the joint.

[0061] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A novel nickel-based filler metal with strong large caulking ability and toughening, characterized in that, It comprises the following components by mass percentage: Boron: 3.5 - 4.0%; Silicon: 4.0 - 5.0%; Titanium: 3.5 - 4.0%; Chromium: 10.0 - 12.0%; Cobalt: 0 - 1.0%; Iron: 3.0 - 5.0%; Nickel: the balance.

2. The novel nickel-based filler metal with strong large caulking ability and toughening as described in claim 1, characterized in that, The melting temperature of the novel nickel-based solder with strong large gap filling ability is 950°C to 1020°C.

3. The novel nickel-based brazing filler metal with strong large caulking ability and toughening, as described in claim 1, is characterized in that The working temperature range of the novel nickel-based solder with strong large gap filling ability is 550 - 600°C.

4. The novel nickel-based brazing filler metal with strong large caulking ability and toughening, as described in claim 1, is characterized in that, It is prepared by the following steps: S1. Weigh the raw materials of each component according to the predetermined mass percentage; S2. Melt the raw materials of each component under a vacuum state to obtain liquid metal; S3. Inhale the liquid metal into an atomizer, and under the atmosphere of a protective gas, atomize it to obtain fine metal droplets, and the metal droplets are quickly cooled and solidified into powder to obtain the novel nickel-based solder with strong large gap filling ability.

5. The novel nickel-based filler metal with strong large caulking ability and toughening as claimed in claim 4, characterized in that, It further includes the following steps: S4. Screen and collect the powder with a mesh size of less than 180 meshes using a 180-mesh sieve.

6. The novel nickel-based filler metal with strong large caulking ability and toughening as described in claim 4, characterized in that, After step S1, it further includes the following steps: After polishing the surface oxide scale and impurities of the raw materials of each component with sandpaper, ultrasonically clean them with an acetone solution for 15 minutes, then ultrasonically clean them with an ethanol solution for 5 minutes, and dry them at a temperature of 60°C.

7. The novel nickel-based brazing filler metal with strong large caulking ability as described in claim 4, characterized in that, Step S2 includes the following steps; Melt the raw materials of each component under a vacuum state; Under the environment of a protective gas, keep it at a temperature of 1550°C for 40 minutes to obtain liquid metal.

8. The novel nickel-based filler metal with strong large caulking ability and toughening, as described in claim 4, is characterized in that In step S3, the atomization pressure is 5 MPa to 7.5 MPa, and the gas flow rate is 10 - 12 m 3 / min.

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