A method for controlling hot cracking in TIG welding of nickel-based heat sink brazing joint areas

Abstract

The application discloses a method for controlling heat cracks in a TIG welding area of a nickel-based radiator brazing seam, and comprises the following steps: increasing the content of Mo element in a welding wire used in TIG welding, so that the mass percentage of the Mo element relative to other elements in the welding wire is increased, thereby allowing the Mo element and a B element in the TIG welding seam to form a high-melting-point compound phase during TIG welding, and preventing the B element in the TIG welding seam from combining with a Ni element to form a low-melting eutectic Ni-B at a grain boundary. The application solves the problem of heat cracks generated in a TIG welding gas collecting cover at a brazing seam position of a nickel-based high-temperature alloy radiator.

Description

Technical Field

[0001] This invention belongs to the field of nickel-based high-temperature alloy radiator core welding technology, specifically a method for controlling TIG weld hot cracking when using TIG welding in the brazing area of ​​nickel-based radiators. Background Technology

[0002] With the increasing demands for high-performance radiators in aircraft, stainless steel radiators can no longer meet the requirements in terms of corrosion resistance, thermal fatigue resistance, and creep resistance. Therefore, nickel-based high-temperature alloy materials with superior performance are selected.

[0003] The brazing filler metal used in nickel-based superalloy heat sinks is Ni-Cr-Si-B. During TIG welding, the weld seam remelts, and the filler metal dissolves into the nickel-based superalloy matrix. Due to compositional segregation caused by rapid cooling, the local content of boron (B) and silicon (Si) elements in the weld seam is relatively high. The solubility of boron in the Ni (nickel) matrix is ​​extremely low, only 0.7%. Therefore, the boron that cannot dissolve into the crystal forms a low-melting-point eutectic Ni-B at the grain boundaries (melting point approximately 1093℃). When the weld solidifies, weld shrinkage causes cracking at the Ni-B eutectic film. Furthermore, boron has a very high crack sensitivity coefficient; increasing the boron concentration by only 500 ppm can increase crack sensitivity fivefold. Therefore, hot cracking is particularly prone to occur during TIG welding of the nickel-based superalloy heat sink core and the gas collector shroud. Summary of the Invention

[0004] This invention aims to provide a method for controlling hot cracking in the brazed seam area of ​​nickel-based heat sinks using TIG welding, thereby solving the problem of hot cracking in the weld seam during TIG welding of the core and the gas collector of nickel-based high-temperature alloy heat sinks.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for controlling hot cracking in the brazed seam area of ​​a nickel-based high-temperature alloy heat sink using TIG welding, wherein the nickel-based high-temperature alloy heat sink includes fins, baffles, seals, and a gas collection shroud made of nickel-based high-temperature alloy material, wherein the fins, baffles, and seals are formed into a core by brazing and then welded to the gas collection shroud by TIG welding, and the method for controlling hot cracking by TIG welding includes: Increasing the Mo content in the welding wire used in TIG welding increases the mass percentage of Mo relative to other elements in the welding wire. This allows Mo to form a high-melting-point compound phase with B in the TIG weld during the welding process, preventing the formation of a low-melting-point eutectic Ni-B at the grain boundaries after B combines with Ni in the TIG weld.

[0006] Furthermore, the method for controlling hot cracking in TIG welding includes the following steps: Step 1: After assembling the fins, partitions and seals, braze them to form the core. The brazing filler metal used is Ni-Cr-Si-B series brazing filler metal. Step 2: The gas collection hood is welded to the end face of the core by TIG welding, and the argon arc weld formed by TIG welding crosses the multiple brazing seams formed between the partition and the seal. ERNiMo-10 welding wire is used for TIG welding.

[0007] As one approach, in step two, before TIG welding, the oxide film on the surface of the welding wire is first cleaned by pickling, and then the welding wire is dried.

[0008] As one approach, in step two, the welding current during TIG welding is 40–50 A, and the compressed gas flow rate is 20–30 L / min.

[0009] As one option, in step two, the diameter of the ERNiMo-10 welding wire is 1.2 mm.

[0010] As one approach, in step two, when the TIG welding is completed, fluorescence detection is used to detect cracks in the argon arc weld.

[0011] Compared with existing TIG welding technology, this invention uses high-molybdenum welding wire for TIG welding of nickel-based high-temperature alloy heat sinks. Even if the interstitial solid solubility of element B in element Mo is 0.6%, and even if element B and element Mo form a compound phase, the melting point of the compound phase is still very high (compared to the melting point of low-melting-point eutectic Ni-B of 1093℃, the melting point of the compound phase formed by element B and element Mo is even higher), so it will not cause hot cracking after TIG welding. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the core structure of a nickel-based high-temperature alloy heat sink; Figure 2 Here is a schematic diagram of the brazing seam structure of the core: In the diagram: 1-Cold edge seal, 2-Partition plate, 3-Hot edge seal, 4-Side plate, 5-Argon arc weld, 6-Gas collection hood, 7-Brazed weld. Detailed Implementation

[0013] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and conventional means in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0014] like Figures 1-2As shown, the core of the nickel-based high-temperature alloy heat sink is mainly composed of cold-edge seal 1, partition 2, hot-edge seal 3, and side plate 4 brazed together. After the core is brazed, a gas collection shroud 6 is welded to both sides of the core using TIG welding. The cold-edge seal 1, partition 2, hot-edge seal 3, side plate 4, and gas collection shroud 6 are all made of nickel-based high-temperature alloy material.

[0015] like Figure 1 As shown, the argon arc weld 5 between the core 1 and the gas collecting hood 6 is a straight weld extending from the upper side plate 4 to the lower side plate 4. The argon arc weld 5 passes through the cold edge seal 1, the partition 2, the hot edge seal 3 and the side plate 4, and affects the brazing weld 7 on the cold edge seal 1, the partition 2, the hot edge seal 3 and the side plate 4.

[0016] This invention discloses a method for controlling hot cracking in the brazed seam area of ​​a nickel-based high-temperature alloy heat sink using TIG welding, comprising the following steps: Step 1: Refer to the following steps: Assemble the fins, cold edge seal 1, partition 2, hot edge seal 3, and side plate 4. Figure 1 After assembly, brazing is performed using Ni-Cr-Si-B brazing filler metal. Once brazing is complete, it forms a single core. Step 2: Pickling removes the oxide film from the surface of the 1.2mm diameter ERNiMo-10 welding wire, followed by drying in a drying oven at 150℃ for 2 hours. (Refer to...) Figure 1 and Figure 2 Assemble the core that was brazed in step one with the gas collecting shroud 6, and then perform TIG welding. Before TIG welding, adjust the TIG welding parameters: welding current 45A, argon flow rate 25L / min. Then, use ERNiMo-10 welding wire with a diameter of 1.2mm to weld the nickel-based high-temperature alloy radiator core and the gas collecting shroud 6. Perform fluorescence detection on the surface of the argon arc weld 5 and check that there are no cracks on the surface of the argon arc weld 5.

[0017] Those skilled in the art can make various adjustments to this application based on the actual circumstances. The general principles defined in this application can be implemented in other embodiments without departing from their connotations. Therefore, this application is not limited to the structure shown in the specific embodiments, but is to be accorded the widest scope consistent with the principles and features set forth in the claims of this application.

Claims

1. A method for controlling hot cracking in the brazed seam area of ​​a nickel-based high-temperature alloy heat sink using TIG welding, wherein the nickel-based high-temperature alloy heat sink comprises fins, baffles, seals, and a gas collection shroud made of nickel-based high-temperature alloy material, wherein, The fins, baffles, and seals are brazed to form a core, which is then welded to the gas collection hood via TIG welding. The method for controlling hot cracking using TIG welding includes: Increasing the Mo content in the welding wire used in TIG welding increases the mass percentage of Mo relative to other elements in the welding wire. This allows Mo to form a high-melting-point compound phase with B in the TIG weld during the welding process, preventing the formation of a low-melting-point eutectic Ni-B at the grain boundaries after B combines with Ni in the TIG weld.

2. The method for controlling hot cracking in the brazed seam area of ​​a nickel-based high-temperature alloy heat sink using TIG welding according to claim 1, characterized in that, Includes the following steps: Step 1: After assembling the fins, partitions and seals, braze them to form the core. The brazing filler metal used is Ni-Cr-Si-B series brazing filler metal. Step 2: The gas collection hood is welded to the end face of the core by TIG welding, and the argon arc weld formed by TIG welding crosses the multiple brazing seams formed between the partition and the seal. ERNiMo-10 welding wire is used for TIG welding.

3. The method for controlling hot cracking in the brazed seam area of ​​a nickel-based high-temperature alloy heat sink using TIG welding according to claim 1, characterized in that, In step two, before TIG welding, the oxide film on the surface of the welding wire is first cleaned by pickling, and then the welding wire is dried.

4. The method for controlling hot cracking in the brazed seam area of ​​a nickel-based high-temperature alloy heat sink using TIG welding according to claim 1, characterized in that, In step two, the welding current during TIG welding is 40-50A, and the compressed gas flow rate is 20-30L / min.

5. The method for controlling hot cracking in the brazed seam area of ​​a nickel-based high-temperature alloy heat sink using TIG welding according to claim 1, characterized in that, In step two, the diameter of the ERNiMo-10 welding wire is 1.2 mm.

6. The method for controlling hot cracking in the brazed seam area of ​​a nickel-based high-temperature alloy heat sink using TIG welding according to claim 1, characterized in that, In step two, when the TIG welding is completed, fluorescence detection is used to detect cracks in the argon arc weld.

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