Electron beam welding method suitable for nickel-cobalt-based dissimilar high-temperature alloy

Abstract

The invention discloses an electron beam welding method suitable for nickel-cobalt-based dissimilar high-temperature alloy. The electron beam welding method comprises the steps that polishing, fluorescence inspection, acid pickling and flushing, part assembling, argon arc welding spot positioning and welding spot polishing cleaning are sequentially carried out on a to-be-welded part of a part; a part is clamped and fixed to a workbench of an electron beam welding machine, the height of a gathering gun is adjusted, a cabin door is closed, vacuumizing is conducted, a welding program is compiled, a welding spot is positioned through an electron beam, welding seam welding is completed through the electron beam welding technology with small current and waveform and oscillation adding, and modification welding is conducted on a welding seam through the small current electron beam welding technology; and transferring the part into a heat treatment furnace from the electron beam welding machine, carrying out heat treatment on the part, taking out the part, and carrying out visual and fluorescence inspection on a welding seam. By means of the method, the occurrence probability of macroscopic and fluorescent display defects can be greatly reduced, the one-time welding qualification rate is increased to about 95%, high-reliability welding of the nickel-cobalt-based dissimilar high-temperature alloy is achieved, the part production period is shortened, the part manufacturing cost is reduced, and unstable factors in the part production process are reduced.

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] In the high-temperature unit body of aircraft engines, GH5188 alloy and GH3536 alloy are widely used. Among them, GH5188 is a solid solution strengthened cobalt-based high-temperature alloy. The alloy is solid solution strengthened by adding 14% tungsten, which makes the alloy have excellent high-temperature thermal strength. A high content of Cr and a trace amount of La are also added to the alloy, which makes the alloy have good high-temperature oxidation resistance. At the same time, it has excellent forming, welding and other process properties. It is suitable for manufacturing aircraft engines that require high strength below 980℃ and oxidation resistance below 1100℃. GH3536 is a nickel-based high-temperature alloy with a high iron content, which is mainly strengthened by Cr and Mo solid solution. It has good oxidation resistance and corrosion resistance, medium endurance and creep strength below 900℃, good cold and hot processing formability and welding performance, and is suitable for manufacturing combustion chamber components and other high-temperature components of aircraft engines. It can be used for a long time below 900℃, and the short-term working temperature can reach 1080℃. Due to the excellent performance of GH5188 alloy and GH3536 alloy at high temperature, 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 the laser selective melting-formed GH5188 alloy splashback plate and the GH3536 alloy vortex finder mounting seat are welded, the probability of defects visible to the naked eye and displayed by fluorescence is very high, and the one-time welding pass rate is only about 20%. Therefore, rework is necessary, and in severe cases, the flame tube may be directly scrapped, which greatly affects the product production cycle and manufacturing cost, and increases the unstable factors in the parts production process. Summary of the invention

[0004] In view of 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 one-time welding pass rate to about 95%, thereby achieving high-reliability welding of nickel-cobalt based dissimilar high-temperature alloys, greatly shortening the production cycle and manufacturing cost of parts, and reducing unstable factors in the parts production process.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme: 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. Firstly, 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 weldment and the cobalt-based weldment to be welded, so that the assembly gap and mismatch between the nickel-based weldment and the cobalt-based weldment meet the design requirements, and then use argon arc welding to position the nickel-based weldment and the cobalt-based weldment along the assembly gap between the nickel-based weldment and the cobalt-based weldment 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 left on the surface of the argon arc positioning welds;

[0013] Step 2: Soldering

[0014] ① First, clamp and fix the parts on the workbench of the electron beam welder, then adjust the focusing gun of the electron beam welder 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 welded parts and the cobalt-based welded parts to ensure 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 deformation of the parts;

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

[0017] ④. Perform electron beam modification welding on the weld to remove micro-crack defects and fish scale patterns 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 positioning welding parameters are: current of 40A to 60A, argon gas flow 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 empty to realize program verification.

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

[0026] In step 3, 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 one-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 It is a schematic diagram of the structure of the combination of the GH5188 alloy splash plate and the GH3536 alloy vortex finder mounting seat 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 seat in the embodiment;

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

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

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

[0036] Step 1: Preparation before welding

[0037] ①, firstly, the part to be welded is coarsely ground by a winch grinder, and then the part to be welded is manually polished to reduce the surface roughness of the part to be welded to below Ra3.2; in this embodiment, the nickel-based welded part 1 is a GH3536 alloy vortex flow device mounting seat, 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 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 the oxides on the surface of the parts to be welded; in this embodiment, the acid solution for pickling is prepared by proportioning hydrofluoric acid, nitric acid, sulfuric acid and water;

[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 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 left 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 focusing gun of the electron beam welder 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 shall not be less than 2×10 -4 mbar, and in the process of vacuuming, the welding program is compiled and the welding program is run through once to realize 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 welded part 1 and the cobalt-based welded part 2 by electron beam welding, ensuring that the electron beam positioning welds are evenly distributed along the assembly gap, and preventing the subsequent welding thermal stress from causing deformation of the parts by electron beam positioning welding; in this embodiment, the number of electron beam positioning welds is four, and the phase angle between any adjacent electron beam positioning welds is 90°;

[0046] ③. Start the prepared welding program and complete the welding of the electron beam weld along the assembly gap between the nickel-based weldment 1 and the cobalt-based weldment 2; wherein, the electron beam welding adopts a welding process with a small current and adds waveform and oscillation, and the focusing current adopts surface focusing, and the welding process parameters are: voltage is 120kV, welding beam current is 4.0mA-4.5mA, welding speed is 12mm / s-15mm / s, focusing current is 2085mA, waveform is a triangular wave, oscillation amplitude is 0.8mm-1.0mm, oscillation frequency is 80Hz-100Hz, arc starting is 90°, and arc closing is 90°; specifically, the use of a small current is to reduce the thermal stress in the welding process, 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 waveforms and oscillation frequencies can play a role in stirring the molten pool, and can also inhibit the aggregation of impurity elements in the welding process 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 small current modification welding process, and the welding process parameters are: voltage is 120kV, welding beam current is 4.0mA~4.5mA, welding speed is 12mm / s~15mm / s, focusing current is 2165mA, waveform is triangular wave, oscillation amplitude is 0.8mm~1.0mm, oscillation frequency is 80Hz~100Hz, arc starting is 90°, arc ending is 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 inspections on the welds of the parts. Figure 4 The figure shows a micrograph of the weld cross section. It can be seen from the figure that the weld is dense inside 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 90mm × 45mm × 1.5mm, and 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 performance and hardness test, and the second subject is the high temperature tensile performance 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, indicating that the welding method of the present invention can ensure the reliability of the mechanical properties of the weld.

[0059] The solutions in the embodiments are not intended to limit the protection scope of the present invention. All equivalent implementations or changes that do not deviate from the present invention are included in the protection scope 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. Firstly, 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 weldment and the cobalt-based weldment to be welded, so that the assembly gap and mismatch between the nickel-based weldment and the cobalt-based weldment meet the design requirements, and then use argon arc welding to position the nickel-based weldment and the cobalt-based weldment along the assembly gap between the nickel-based weldment and the cobalt-based weldment 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 left on the surface of the argon arc positioning welds; Step 2: Soldering ① First, clamp and fix the parts on the workbench of the electron beam welder, then adjust the focusing gun of the electron beam welder 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 welded parts and the cobalt-based welded parts to ensure 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 deformation of the parts; ③. Start the prepared welding program and complete the electron beam welding along the assembly gap between the nickel-based welded parts and the cobalt-based welded parts. The electron beam welding adopts a welding process with a small current and added waveform and oscillation, and the focusing current adopts surface focusing; ④. Perform electron beam modification welding on the weld to remove micro-crack defects and fish scale patterns 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 positioning welding parameters are: current of 40A to 60A, argon gas flow 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 empty to realize 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 is 120kV, welding beam current is 4.0mA~4.5mA, welding speed is 12mm / s~15mm / s, focusing current is 2085mA, waveform is triangular wave, oscillation amplitude is 0.8mm~1.0mm, oscillation frequency is 80Hz~100Hz, arc starting is 90°, and arc ending is 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 of 90°, and arc ending 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, the heat treatment temperature is 900°C to 950°C, and the heat treatment time is 2 hours.

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