An electron beam welding method suitable for nickel-cobalt based dissimilar high-temperature alloys

Abstract

An electron beam welding method suitable for nickel-cobalt-based dissimilar high-temperature alloys comprises the following steps: polishing, fluorescent inspection, pickling, and rinsing the parts to be welded; assembling the parts; locating weld points with argon arc; and polishing and cleaning the weld points. The parts are clamped and fixed to the workbench of the electron beam welder, the gun height is adjusted, the hatch is closed, vacuum is evacuated, and a welding program is compiled. The electron beam locates the weld points, and the weld is welded using a low-current electron beam welding process with waveform and oscillation. The weld is then finished using a low-current electron beam welding process. The weld is then finished using a low-current electron beam welding process. The parts are then removed from the electron beam welder and placed in a heat treatment furnace for heat treatment. The parts are then removed and the welds are visually and fluorescently inspected. This method significantly reduces the incidence of defects visible to the naked eye and those indicated by fluorescent light, increasing the first-pass weld yield to approximately 95%. This method achieves high-reliability welding of nickel-cobalt-based dissimilar high-temperature alloys, shortens part production cycle and manufacturing costs, and reduces instability during part production.

Description

Technical Field

[0001] The invention belongs to the technical field of metal welding, and in particular relates to an electron beam welding method suitable for nickel-cobalt based dissimilar high-temperature alloys. Background Art

[0002] GH5188 and GH3536 alloys are widely used in high-temperature components of aircraft engines. GH5188 is a solid-solution-strengthened cobalt-based superalloy. The addition of 14% tungsten achieves this, resulting in excellent high-temperature thermal strength. High levels of chromium and trace amounts of lanthanum contribute to its excellent high-temperature oxidation resistance, along with excellent forming and weldability. It is suitable for manufacturing aircraft engine parts requiring high strength below 980°C and oxidation resistance below 1100°C. GH3536, a nickel-based superalloy with a high iron content, is solid-solution-strengthened primarily with chromium and molybdenum. It exhibits excellent oxidation and corrosion resistance, moderate endurance and creep strength below 900°C, and good hot and cold formability and weldability. It is suitable for manufacturing combustion chamber components and other high-temperature components in aircraft engines, with long-term use below 900°C and short-term operating temperatures up to 1080°C. Due to the excellent performance of GH5188 alloy and GH3536 alloy at high temperatures, they are widely used in high-temperature units of aircraft engines such as combustion chambers, afterburners, tail nozzles and other units.

[0003] However, taking the manufacturing process of aircraft engine flame tubes as an example, when welding the GH5188 alloy splash plate and the GH3536 alloy vortex finder mounting base formed by laser selective melting, the probability of defects visible to the naked eye and displayed by fluorescence is very high, and the qualified rate of one-time welding is only about 20%, so rework is necessary. In severe cases, it may directly lead to the scrapping of the flame tube, which greatly affects the production cycle and manufacturing cost of the product and increases the instability factors in the parts production process. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention provides an electron beam welding method suitable for nickel-cobalt-based dissimilar high-temperature alloys, which greatly reduces the probability of defects visible to the naked eye and displayed by fluorescence, and increases the first-time welding pass rate to about 95%. It realizes high-reliability welding of nickel-cobalt-based dissimilar high-temperature alloys, greatly shortens the production cycle and manufacturing cost of parts, and reduces unstable factors in the part production process.

[0005] To achieve the above object, the present invention adopts the following technical solution: an electron beam welding method suitable for nickel-cobalt based dissimilar high temperature alloys, comprising the following steps:

[0006] Step 1: Preparation before welding

[0007] ①. First, use a grinder to roughly grind the parts to be welded, and then manually polish the parts to be welded to reduce the surface roughness of the parts to be welded to below Ra3.2;

[0008] ②. Conduct fluorescent inspection on the parts to be welded to ensure there are no defects before welding;

[0009] ③. Pickle the parts to be welded to remove the oxides on the surface of the parts to be welded;

[0010] ④. Use distilled water to rinse the parts to be welded so that there is no acid residue on the surface of the parts to be welded;

[0011] ⑤. First, assemble the nickel-based parts to be welded and the cobalt-based parts to be welded so that the assembly gap and mismatch between the nickel-based parts to be welded and the cobalt-based parts to be welded meet the design requirements. Then, use argon arc welding to position the nickel-based parts to be welded and the cobalt-based parts to be welded along the assembly gap between the nickel-based parts to be welded and the cobalt-based parts to be welded, ensuring that the argon arc positioning welding points are evenly distributed along the assembly gap.

[0012] ⑥ First, manually polish the argon arc positioning welds, and then clean them with alcohol and distilled water to ensure that there are no impurities remaining on the surface of the argon arc positioning welds;

[0013] Step 2: Soldering

[0014] ① First, clamp the parts on the workbench of the electron beam welder, then adjust the electron beam welder's gun to the set height, then close the hatch of the electron beam welder, and then evacuate the vacuum chamber of the electron beam welder;

[0015] ② Use electron beam welding to reposition the parts along the assembly gap between the nickel-based and cobalt-based parts to be welded, ensuring that the electron beam positioning welds are evenly distributed along the assembly gap. Electron beam positioning welding is used to prevent subsequent welding thermal stress from causing part deformation.

[0016] ③. Start the prepared welding program and complete the electron beam welding along the assembly gap between the nickel-based and cobalt-based parts to be welded. The electron beam welding adopts a welding process with low current, waveform and oscillation, and the focusing current adopts surface focusing;

[0017] ④. Perform electron beam modification welding on the weld to remove micro-cracks and fish scales on the weld surface;

[0018] Step 3: Post-weld heat treatment

[0019] ① First restore the vacuum chamber of the electron beam welder to normal pressure, then open the hatch of the electron beam welder, and then remove the welded parts from the workbench of the electron beam welder;

[0020] ②. Send the parts into the heat treatment furnace for heat treatment;

[0021] ③. Take the parts out of the heat treatment furnace and conduct visual and fluorescent inspections on the welds of the parts.

[0022] In step 1 (1), the argon arc spot welding parameters are: current of 40A to 60A, argon gas flow rate of 8L / min to 10L / min, tungsten electrode diameter of 2mm, and no wire feeding during the spot welding process.

[0023] In step 2, the vacuum degree of the vacuum chamber is not less than 2×10 -4 mbar, and during the vacuuming process, complete the preparation of the welding program and run the welding program again to realize the program verification.

[0024] In step 2 (3), the welding process parameters are: voltage of 120 kV, welding beam current of 4.0 mA to 4.5 mA, welding speed of 12 mm / s to 15 mm / s, focusing current of 2085 mA, waveform of triangular wave, oscillation amplitude of 0.8 mm to 1.0 mm, oscillation frequency of 80 Hz to 100 Hz, arc starting angle of 90°, and arc ending angle of 90°.

[0025] In step 2 (4), the welding process parameters are: voltage of 120 kV, welding beam current of 4.0 mA to 4.5 mA, welding speed of 12 mm / s to 15 mm / s, focusing current of 2165 mA, waveform of triangular wave, oscillation amplitude of 0.8 mm to 1.0 mm, oscillation frequency of 80 Hz to 100 Hz, arc starting angle of 90°, and arc ending angle of 90°.

[0026] In step 3 (2), the heat treatment temperature is 900°C to 950°C, and the heat treatment time is 2 hours.

[0027] Beneficial effects of the present invention:

[0028] The electron beam welding method of the present invention, which is applicable to nickel-cobalt-based dissimilar high-temperature alloys, greatly reduces the probability of defects visible to the naked eye and displayed by fluorescence, increases the first-time welding pass rate to about 95%, realizes high-reliability welding of nickel-cobalt-based dissimilar high-temperature alloys, greatly shortens the production cycle and manufacturing cost of parts, and reduces unstable factors in the part production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the structure of the assembly of the GH5188 alloy splash plate and the GH3536 alloy vortex finder mounting base in the embodiment;

[0030] Figure 2 for Figure 1 Middle AA section view;

[0031] Figure 3 is a position distribution diagram of the positioning welding points relative to the parts in the embodiment;

[0032] Figure 4 This is a cross-sectional micrograph of the weld of the assembly of the GH5188 alloy splash plate and the GH3536 alloy vortex finder mounting base in the embodiment;

[0033] In the figure, 1 is nickel-based workpiece to be welded, 2 is cobalt-based workpiece to be welded, and 3 is positioning welding point. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] An electron beam welding method suitable for nickel-cobalt based dissimilar high-temperature alloys comprises the following steps:

[0036] Step 1: Preparation before welding

[0037] ①, first use a winch grinder to rough grind the parts to be welded, and then manually polish the parts to be welded to reduce the surface roughness of the parts to be welded to below Ra3.2; in this embodiment, the nickel-based welded part 1 is a GH3536 alloy eddy current mount, the cobalt-based welded part 2 is a GH5188 alloy splash plate, and the weld height is 1.5 mm. Figure 1 、 2 As shown; In addition, the GH5188 alloy splash plate can be produced by casting, forging or additive manufacturing, and its initial surface roughness is about Ra6.3, while the GH3536 alloy vortex finder mounting seat is made by milling, and its surface is relatively smooth, so the GH5188 alloy splash plate only needs to be ground and polished;

[0038] ②. Conduct fluorescent inspection on the parts to be welded to ensure there are no defects before welding;

[0039] ③ Pickling the parts to be welded to remove oxides on the surface of the parts to be welded; in this embodiment, the acidic solution used for pickling is prepared by mixing hydrofluoric acid, nitric acid, sulfuric acid and water in proportion;

[0040] ④. Use distilled water to rinse the parts to be welded so that there is no acid residue on the surface of the parts to be welded;

[0041] ⑤. First, assemble the nickel-based workpiece 1 to be welded and the cobalt-based workpiece 2 to be welded, so that the assembly gap and mismatch between the nickel-based workpiece 1 to be welded and the cobalt-based workpiece 2 to be welded meet the design requirements, and then use argon arc welding to position the nickel-based workpiece 1 and the cobalt-based workpiece 2 along the assembly gap between the nickel-based workpiece 1 and the cobalt-based workpiece 2 to ensure that the argon arc positioning welds 3 are evenly distributed along the assembly gap; wherein, the argon arc positioning welding parameters are: current of 40A to 60A, argon gas flow rate of 8L / min to 10L / min, tungsten electrode diameter of 2mm, and no wire feeding during the spot welding process; in this embodiment, the number of argon arc positioning welds 3 is four, and the phase angle between any adjacent argon arc positioning welds 3 is 90°, as shown in FIG. Figure 3 As shown;

[0042] ⑥ First, manually polish the argon arc positioning welds, and then clean them with alcohol and distilled water to ensure that there are no impurities remaining on the surface of the argon arc positioning welds;

[0043] Step 2: Soldering

[0044] ① First, clamp the parts on the workbench of the electron beam welder, then adjust the electron beam welder's gun to the set height, then close the hatch of the electron beam welder, and then evacuate the vacuum chamber of the electron beam welder; the vacuum degree of the vacuum chamber should not be less than 2×10 -4 mbar, and during the vacuuming process, the welding program is compiled and the welding program is run through once to achieve program verification; in this embodiment, the height of the focusing gun is 300mm;

[0045] ② Repositioning the parts along the assembly gap between the nickel-based workpiece 1 and the cobalt-based workpiece 2 by electron beam welding to ensure that the electron beam tack welds are evenly distributed along the assembly gap. Electron beam tack welding is used to prevent deformation of the parts caused by subsequent welding thermal stress. In this embodiment, the number of electron beam tack welds is four, and the phase angle between any adjacent electron beam tack welds is 90°.

[0046] ③. Start the prepared welding program and complete the electron beam weld along the assembly gap between the nickel-based workpiece 1 to be welded and the cobalt-based workpiece 2 to be welded; wherein, the electron beam welding adopts a welding process with a small current and the addition of waveform and oscillation, and the focusing current adopts surface focusing, and the welding process parameters are: voltage of 120kV, welding beam current of 4.0mA~4.5mA, welding speed of 12mm / s~15mm / s, focusing current of 2085mA, waveform of triangular wave, oscillation amplitude of 0.8mm~1.0mm, oscillation frequency of 80Hz~100Hz, arc starting of 90°, and arc ending of 90°; specifically, the use of a small current is to reduce the thermal stress during welding, thereby reducing the tendency to form microcracks, and at the same time, it can also reduce the size of the molten pool, reduce the amount of parent metal melted, and reduce the impurity content in the molten pool to form oxides. Adding waveform and oscillation frequency can play a role in stirring the molten pool, and can also inhibit the aggregation of impurity elements during welding to form large particles of oxides;

[0047] ④. Electron beam modification welding is performed on the weld to remove microcrack defects and fish scale patterns on the weld surface. The electron beam modification welding adopts a low current modification welding process with the following welding process parameters: voltage of 120kV, welding beam current of 4.0mA to 4.5mA, welding speed of 12mm / s to 15mm / s, focusing current of 2165mA, waveform of triangular wave, oscillation amplitude of 0.8mm to 1.0mm, oscillation frequency of 80Hz to 100Hz, arc starting angle of 90°, arc ending angle of 90°;

[0048] Step 3: Post-weld heat treatment

[0049] ① First restore the vacuum chamber of the electron beam welder to normal pressure, then open the hatch of the electron beam welder, and then remove the welded parts from the workbench of the electron beam welder;

[0050] ②. Send the parts into the heat treatment furnace for heat treatment; the heat treatment temperature is 900℃~950℃ and the heat treatment time is 2h;

[0051] ③. Take the parts out of the heat treatment furnace and conduct visual and fluorescent inspection on the welds of the parts. Figure 4 The figure shows a cross-sectional micrograph of the weld. It can be seen from the figure that the weld is dense and has no defects such as incomplete fusion.

[0052] In addition, in order to evaluate the welding performance, butt welding tests were carried out on GH5188 alloy specimens and GH3536 alloy specimens. The specimen dimensions (length × width × thickness) were both 90mm × 45mm × 1.5mm. The welding method of the specimens was exactly the same as that of the actual parts.

[0053] The performance evaluation is divided into two subjects. The first subject is the room temperature tensile property and hardness test, and the second subject is the high temperature tensile property test. The number of test objects in each subject is four. The test results are shown in Tables 1 and 2.

[0054] Table 1. Room temperature tensile properties and hardness test results

[0055]

[0056] Table 1. High temperature tensile properties test results

[0057]

[0058] Furthermore, the fracture positions of all the butt-welded test pieces were located on one side of the GH3536 alloy test piece, and none occurred at the weld seam, indicating that the welding method of the present invention can ensure the reliability of the mechanical properties of the weld seam.

[0059] The solutions in the embodiments are not intended to limit the scope of protection of the present invention. All equivalent implementations or modifications that do not depart from the scope of protection of the present invention are included in the scope of protection of the present invention.

Claims

1. An electron beam welding method suitable for nickel-cobalt based dissimilar high temperature alloys, characterized in that: The steps include: Step 1: Preparation before welding ①. First, use a grinder to roughly grind the parts to be welded, and then manually polish the parts to be welded to reduce the surface roughness of the parts to be welded to below Ra3.2; ②. Conduct fluorescent inspection on the parts to be welded to ensure there are no defects before welding; ③. Pickle the parts to be welded to remove the oxides on the surface of the parts to be welded; ④. Use distilled water to rinse the parts to be welded so that there is no acid residue on the surface of the parts to be welded; ⑤. First, assemble the nickel-based parts to be welded and the cobalt-based parts to be welded so that the assembly gap and mismatch between the nickel-based parts to be welded and the cobalt-based parts to be welded meet the design requirements. Then, use argon arc welding to position the nickel-based parts to be welded and the cobalt-based parts to be welded along the assembly gap between the nickel-based parts to be welded and the cobalt-based parts to be welded, ensuring that the argon arc positioning welding points are evenly distributed along the assembly gap. ⑥ First, manually polish the argon arc positioning welds, and then clean them with alcohol and distilled water to ensure that there are no impurities remaining on the surface of the argon arc positioning welds; Step 2: Soldering ① First, clamp the parts on the workbench of the electron beam welder, then adjust the electron beam welder's gun to the set height, then close the hatch of the electron beam welder, and then evacuate the vacuum chamber of the electron beam welder; ② Use electron beam welding to reposition the parts along the assembly gap between the nickel-based and cobalt-based parts to be welded, ensuring that the electron beam positioning welds are evenly distributed along the assembly gap. Electron beam positioning welding is used to prevent subsequent welding thermal stress from causing part deformation. ③. Start the prepared welding program and complete the electron beam welding along the assembly gap between the nickel-based and cobalt-based parts to be welded. The electron beam welding adopts a welding process with low current, waveform and oscillation, and the focusing current adopts surface focusing; ④. Perform electron beam modification welding on the weld to remove micro-cracks and fish scales on the weld surface; Step 3: Post-weld heat treatment ① First restore the vacuum chamber of the electron beam welder to normal pressure, then open the hatch of the electron beam welder, and then remove the welded parts from the workbench of the electron beam welder; ②. Send the parts into the heat treatment furnace for heat treatment; ③. Take the parts out of the heat treatment furnace and conduct visual and fluorescent inspections on the welds of the parts.

2. The electron beam welding method for nickel-cobalt based dissimilar high temperature alloys according to claim 1, characterized in that: In step 1 (1), the argon arc spot welding parameters are: current of 40A to 60A, argon gas flow rate of 8L / min to 10L / min, tungsten electrode diameter of 2mm, and no wire feeding during the spot welding process.

3. The electron beam welding method for nickel-cobalt based dissimilar high temperature alloys according to claim 1, characterized in that: In step 2, the vacuum degree of the vacuum chamber is not less than 2×10 -4 mbar, and during the vacuuming process, complete the preparation of the welding program and run the welding program again to realize the program verification.

4. The electron beam welding method for nickel-cobalt based dissimilar high temperature alloys according to claim 1, characterized in that: In step 2 (3), the welding process parameters are: voltage of 120 kV, welding beam current of 4.0 mA to 4.5 mA, welding speed of 12 mm / s to 15 mm / s, focusing current of 2085 mA, waveform of triangular wave, oscillation amplitude of 0.8 mm to 1.0 mm, oscillation frequency of 80 Hz to 100 Hz, arc starting angle of 90°, and arc ending angle of 90°.

5. The electron beam welding method for nickel-cobalt based dissimilar high temperature alloys according to claim 1, characterized in that: In step 2 (4), the welding process parameters are: voltage of 120 kV, welding beam current of 4.0 mA to 4.5 mA, welding speed of 12 mm / s to 15 mm / s, focusing current of 2165 mA, waveform of triangular wave, oscillation amplitude of 0.8 mm to 1.0 mm, oscillation frequency of 80 Hz to 100 Hz, arc starting angle of 90°, and arc ending angle of 90°.

6. The electron beam welding method for nickel-cobalt based dissimilar high temperature alloys according to claim 1, characterized in that: In step 3 (2), the heat treatment temperature is 900°C to 950°C, and the heat treatment time is 2 hours.

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