A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy

Abstract

A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy belongs to the technical field of laser processing. The present invention aims to solve the problems of difficult welding between electroformed nickel and GH4169 material, the occurrence of unfused defects in electron beam welding, and poor welding performance for large thickness. The method includes: 1. Assembly of the welded parts; 2. Low-vacuum laser welding. The present invention is used for low-vacuum laser welding of electroformed nickel / GH4169 superalloy.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser processing. Background Art

[0002] Heterogeneous material weldments are widely used in the fields of aviation, aerospace, automobiles, etc., and have unique advantages in aspects such as weight reduction and performance improvement. In the welding of dissimilar metals, due to the large differences in thermophysical properties between the two materials, brittle phases are likely to be generated, large residual stresses are produced, and process defects occur, etc. Electroformed nickel is high-purity nickel produced by electroforming, and has properties such as high strength, high-temperature oxidation resistance, and corrosion resistance, and is widely used in the fields of aerospace, shipbuilding, and nuclear industry, etc. GH4169 is an iron-nickel-chromium-based wrought superalloy, and its corresponding American grade is IN718. It has excellent high-temperature strength, high-temperature resistance, and corrosion resistance, and can serve in an environment of -253 to 650 °C. It is usually applied to key components in the fields of aerospace, nuclear power, petrochemical, and metallurgical engineering.

[0003] When welding heterogeneous materials of electroformed nickel and superalloy GH4169, the following problems usually exist: (1) During the welding process, problems such as pores, cracks, and grain coarsening are likely to occur on the electroformed nickel side, and it is difficult to overcome; (2) Since Ni is chemically more affinity with S and P elements, low-melting eutectics are likely to be formed due to element segregation during solidification. The low-melting eutectics are distributed in the form of a thin film at the grain boundaries and will crack along the grain boundaries when stressed. At the same time, the low-melting eutectics will also promote the formation of solidification cracks and reduce the strength of the welded joint; (3) When welding in an atmospheric environment, even if gas protection is applied, the entire welding process will inevitably come into contact with the atmosphere during the whole process, resulting in oxidation of the weld seam and adverse metallurgical reactions; (4) The microstructure of electroformed nickel is mainly a single-phase austenite structure, and excessive grain growth is likely to occur in the heat-affected zone on the nickel side. A larger heat input will increase the width of the heat-affected zone; (5) During the welding process, due to the weak fluidity of the molten pool, the formed gas is difficult to escape from the molten pool in time, resulting in pore defects in the weld seam; (6) It is difficult to achieve a large depth-to-width ratio welding in conventional welding processes, and it is not competent when welding butt joints of large-thickness electroformed nickel and GH4169.

[0004] For the above reasons, traditional welding methods cannot achieve the dissimilar metal welding of electroformed nickel and GH4169, and defects will appear in the weld and heat affected zone, resulting in the weakening of joint performance and difficulty in meeting the usage requirements. Especially for the welding of thick electroformed nickel and GH4169, the only welding method that can be adopted is high-energy beam welding. However, the properties of electroformed nickel and GH4169 are very different, and serious magnetic deflection will occur during electron beam welding. Specifically, the tip of the electron beam will deflect towards the GH4169 side, and unfused defects will appear at the bottom of the weld. Conventional laser welding is carried out in the atmospheric environment, and the depth-width ratio of the weld is small. When welding thick plates, it cannot be formed in one pass, and problems such as cracks, slag inclusions and grain coarsening will also occur, and the joint performance is difficult to meet the engineering application requirements. Therefore, there is currently no reliable welding method for the welding of thick electroformed nickel and GH4169. Summary of the Invention

[0005] The present invention aims to solve the problems of difficult welding of electroformed nickel and GH4169 materials, unfused defects occurring during electron beam welding, and poor welding performance for thick plates, and provides a low-vacuum laser welding method for electroformed nickel / GH4169 superalloy.

[0006] A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy is carried out according to the following steps:

[0007] I. Weldment assembly:

[0008] Assemble electroformed nickel and GH4169 so that the butt surfaces fit tightly, and then use a laser for spot fixation. Fix the spot-fixed weldment on the low-vacuum laser welding platform in the vacuum chamber.

[0009] II. Low-vacuum laser welding:

[0010] Under the conditions that the vacuum environment pressure is 0.1 Pa to 10 kPa, argon atmosphere, laser power is 2 kW to 10 kW, laser beam incident angle is 70° to 110°, spot diameter is 0.4 mm to 4 mm, welding speed is 0.1 m / min to 2 m / min, and defocus amount is -15 mm to 0 mm, align the welding laser spot on the center line of the weld without offset, and the laser head moves along the welding path to form a weld. After welding, cool the weldment in a low-vacuum environment, take out the weldment, and thus complete the low-vacuum laser welding method for electroformed nickel / GH4169.

[0011] The beneficial effects of the present invention are:

[0012] (1) The present invention makes up for the deficiencies of traditional laser welding, realizes the welding of electroformed nickel / GH4169 thick plates, and solves the long-standing industry problems. When electron beam welding is used, due to the magnetic deflection effect, the tip will deflect towards GH4169. By adopting the butt joint structure of electroformed nickel / GH4169, the laser focusing spot is centered on the butt joint interface, and welding is carried out in a low-vacuum environment with an ambient pressure below 10 kPa. The weld formation is good, and a reliable connection between electroformed nickel and GH4169 is achieved.

[0013] (2) A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy of the present invention can achieve welding of large thickness without opening a groove. The lower chamber pressure greatly reduces the plume generated during the welding process, reduces the attenuation effect on the laser, increases the weld penetration depth, and realizes welding with a large depth-to-width ratio.

[0014] (3) A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy of the present invention has a concentrated energy density, high welding efficiency, small heat input, and a narrower heat-affected zone, effectively suppressing the coarsening of grains in the heat-affected zone.

[0015] (4) A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy of the present invention has very little residual air in the chamber and no oxidation appears in the weld. In addition, after reaching the specified ambient pressure, argon is introduced for a period of time, and then the introduced argon is gradually reduced. When the argon flow rate is the same as the vacuum pumping speed at the preset ambient pressure, the pressure in the chamber remains constant, and then the welding operation starts. During this process, the introduction of argon further protects the welded joint and effectively prevents joint oxidation.

[0016] (5) A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy of the present invention has less molten metal, a fast cooling rate, small element segregation, and effectively suppresses the appearance of intergranular weak tissues. In addition, welding is carried out in a low-vacuum environment, the boiling point of the material decreases, while the solidus temperature of the material changes little, so the liquid-vapor interface and the solid-liquid interface are very close, that is, the liquid metal layer is very thin, and the welding process is stable.

[0017] (6) A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy of the present invention has no defects (pores, cracks, and grain coarsening) inside the weld, effectively improving the weld performance. Under low-vacuum conditions, the flow pattern of the liquid metal inside the keyhole changes, and the flow direction of the liquid metal is upward along the back wall of the keyhole. This flow pattern is conducive to the escape of bubbles inside the molten pool, so pore defects are not likely to appear inside the weld. In electron beam welding, which is also a high-energy beam, when the focused electron beam is centered on the weld center line, due to the large difference in material properties, the tip of the electron beam will deflect towards the GH4169 side, and unfused defects will appear at the bottom of the weld. Therefore, electron beam welding often needs to deviate towards the pure nickel side. In this method, the focused laser beam is centered on the weld center line, realizing the welding of relatively thick electroformed nickel / GH4169 joints without unfused defects at the bottom.

[0018] That is, the low-vacuum laser welding method for electroformed nickel / GH4169 of the present invention ensures the weld penetration while eliminating defects such as cracks, pores, and grain coarsening caused by traditional welding processes.

[0019] The present invention relates to a low-vacuum laser welding method for electroformed nickel / GH4169 superalloy. Brief Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the low-vacuum laser welding method for electroformed nickel / GH4169 superalloy in Example 1. 1 is a 10kW fiber laser, 2 is a 200μm optical fiber, 3 is a vacuum chamber, 4 is a laser head, 5 is a Roots pump, 6 is a mechanical pump, 7 is a low-vacuum laser welding platform, 8 is a welded part, and 9 is the welding direction;

[0021] Figure 2 It is a schematic diagram of the butt joint structure of the low-vacuum laser welding method for electroformed nickel / GH4169 superalloy of the present invention. 10 is GH4169 material, and 11 is electroformed nickel;

[0022] Figure 3 It is a schematic diagram of the weld of electron beam welding for butt joints of thick plate electroformed nickel / GH4169 superalloy. 12 is an unfused defect;

[0023] Figure 4 It is a schematic diagram of the weld of the low-vacuum laser welding of electroformed nickel / GH4169 superalloy of the present invention. a is the weld width, b is the weld penetration, c is the bottom locking depth, and d is the bottom locking width;

[0024] Figure 5 It is a physical diagram of the surface morphology and cross-sectional morphology of the welded part after welding in Example 1. a is the surface morphology, and b is the cross-sectional morphology;

[0025] Figure 6It is a physical diagram of the surface morphology and cross-sectional morphology of the welded part after Example 2. a is the surface morphology and b is the cross-sectional morphology;

[0026] Figure 7 It is the Ni-side element distribution map of the welded joint of the welded part after Example 2;

[0027] Figure 8 It is a physical diagram of the surface morphology and cross-sectional morphology of the welded part after Example 3. a is the surface morphology and b is the cross-sectional morphology. Specific Embodiments

[0028] The technical solution of the present invention is not limited to the specific embodiments listed below, and also includes any combination between the specific embodiments.

[0029] Specific Embodiment 1: A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy is carried out according to the following steps:

[0030] I. Weldment Assembly:

[0031] Assemble the electroformed nickel and GH4169 so that the butt surfaces fit tightly, and then use a laser for spot fixing. Fix the spot-fixed weldment on the low-vacuum laser welding platform in the vacuum chamber;

[0032] II. Low-Vacuum Laser Welding:

[0033] Under the conditions that the vacuum environment pressure is 0.1 Pa - 10 kPa, argon atmosphere, laser power is 2 kW - 10 kW, laser beam incident angle is 70° - 110°, spot diameter is 0.4 mm - 4 mm, welding speed is 0.1 m / min - 2 m / min, and defocus amount is -15 mm - 0 mm, align the welding laser spot on the center line of the weld seam without offset, and let the laser head move along the welding path to form a weld seam. After welding is completed, cool the weldment in a low-vacuum environment and take out the weldment, thus completing the low-vacuum laser welding method for electroformed nickel / GH4169.

[0034] Table 1 Main Chemical Compositions of Electroformed Nickel and GH4169

[0035]

[0036] Before welding in this specific embodiment, welding parameters need to be set. The laser power is controlled by programming the laser control software, and the welding speed, defocus amount, and offset amount are controlled by programming the vacuum chamber control panel.

[0037] In this specific embodiment, in order to achieve a vacuum environment in the chamber, the chamber can be equipped with an independent vacuum pumping control system and a secondary vacuum pumping system. The front stage is a mechanical pump, and the rear stage is a Roots pump. First, the mechanical pump is turned on. When the ambient pressure drops below 16 kPa, the Roots pump is turned on. Compared with the mechanical pump, the Roots pump has a faster vacuum pumping speed. However, it cannot work at high ambient pressures. Therefore, when the ambient pressure is below 16 kPa, the preset pressure can be quickly reached. After reaching the specified ambient pressure, a certain amount of argon is introduced into the chamber. At this time, the ambient pressure in the chamber will rise slowly. Then, the intake air volume is adjusted downward, and the ambient pressure in the chamber drops. When the preset ambient pressure is reached again, the vacuum pumping speed of the vacuum pump is balanced with the gas filling speed, so as to keep the ambient pressure in the chamber constant.

[0038] The selection of welding parameters in this specific embodiment is closely related to the thickness of the welded part. For example, the negative defocus amount is to set the laser focusing position inside the welded part. The greater the thickness of the welded part, the greater the negative defocus amount, so as to achieve a greater welding depth and realize the welding of thick plates.

[0039] When electron beam welding dissimilar materials, due to the differences in the thermophysical properties of the materials and the inherent characteristics of the electron beam, a magnetic deflection phenomenon will occur. The electron beam deflects towards one side of the material, forming an unfused defect at the tip of the joint, as Figure 3 shown. However, the method of low-vacuum laser welding used in this specific embodiment will not have a deflection problem, as Figure 4 shown.

[0040] The beneficial effects of this embodiment are as follows:

[0041] (1) This embodiment makes up for the deficiencies of traditional laser welding, realizes the welding of electroformed nickel / GH4169 thick plates, and solves the long-standing industry problems. When using electron beam welding, due to the magnetic deflection effect, the tip will deflect towards GH4169. Using an electroformed nickel / GH4169 butt joint structure, the laser focusing spot is centered on the butt joint interface, and welding is carried out in a low-vacuum environment with an ambient pressure below 10 kPa. The weld formation is good, realizing a reliable connection between electroformed nickel and GH4169, and the tensile strength can reach 400 MPa.

[0042] (2) A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy in this embodiment can achieve welding of large thickness without opening a groove. The lower chamber pressure greatly reduces the plume generated during the welding process, reduces the attenuation effect on the laser, increases the weld penetration depth, and realizes welding with a large depth-to-width ratio.

[0043] (3) A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy in this embodiment has a concentrated energy density, high welding efficiency, small heat input, a narrower heat-affected zone is formed, and effectively inhibits the grain coarsening in the heat-affected zone.

[0044] (4) A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy in this embodiment has very little residual air in the chamber and no oxidation appears in the weld. In addition, after reaching the specified ambient pressure in this method, argon is introduced for a period of time, and then the introduced argon is gradually reduced. The argon flow rate is the same as the vacuum pumping speed at the preset ambient pressure. At this time, the pressure in the chamber remains constant, and then the welding operation is started. During this process, the introduction of argon further protects the welded joint and effectively prevents joint oxidation.

[0045] (5) A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy in this embodiment has less molten metal, a fast cooling rate, and small element segregation, effectively suppressing the appearance of intergranular weak tissues. In addition, welding is carried out in a low-vacuum environment. The boiling point of the material decreases, while the solidus temperature of the material changes little. Therefore, the liquid-gas interface and the solid-liquid interface are very close, that is, the liquid metal layer is very thin and the welding process is stable.

[0046] (6) A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy in this embodiment has no defects (pores, cracks, and grain coarsening) inside the weld, effectively improving the mechanical properties of the weld. Under low-vacuum conditions, the flow pattern of the liquid metal inside the keyhole changes, and the flow direction of the liquid metal is upward along the back wall of the keyhole. This flow pattern is conducive to the escape of bubbles inside the molten pool, so it is not easy to appear pore defects inside the weld. In electron beam welding, which is also a high-energy beam, when the focused electron beam is centered on the weld center line, due to the large difference in material properties, the tip of the electron beam will deflect towards the GH4169 side, and unfused defects will appear at the bottom of the weld. Therefore, electron beam welding often needs to deviate towards the pure nickel side. In this method, the focused laser beam is centered on the weld center line, realizing the welding of a relatively thick electroformed nickel / GH4169 joint without unfused defects at the bottom.

[0047] That is, the low-vacuum laser welding method for electroformed nickel / GH4169 in this embodiment ensures the weld penetration while eliminating defects such as cracks, pores, and grain coarsening caused by traditional welding processes.

[0048] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that the electroformed nickel and GH4169 described in step 1 are electroformed nickel and GH4169 after acetone cleaning. Others are the same as specific embodiment 1.

[0049] This specific embodiment processes the material into a butt joint structure with a flat surface. Before welding, wipe the surface of the welded part with acetone to remove oil, moisture, and other contaminants on the surface of the welded part to avoid adverse effects on the welded joint.

[0050] Specific Embodiment 3: The difference between this embodiment and either of Specific Embodiments 1 or 2 is that: the thicknesses of the electroformed nickel and GH4169 in Step 1 are both 5 mm to 30 mm. Others are the same as in Specific Embodiment 1 or 2.

[0051] Specific Embodiment 4: With reference to Figure 2 Specifically described, the difference between this embodiment and any one of Specific Embodiments 1 to 3 is that: in Step 1, the electroformed nickel and GH4169 are assembled to form a butt joint or a lock-bottom butt joint. Others are the same as in Specific Embodiments 1 to 3.

[0052] Specific Embodiment 5: The difference between this embodiment and any one of Specific Embodiments 1 to 4 is that: when the electroformed nickel and GH4169 are assembled to form a lock-bottom butt joint, the lock-bottom width is 2 mm to 9 mm, and the lock-bottom depth is 4 mm to 28 mm. Others are the same as in Specific Embodiments 1 to 4.

[0053] Specific Embodiment 6: The difference between this embodiment and any one of Specific Embodiments 1 to 5 is that: in Step 1, laser spot fixation is adopted, which is specifically carried out according to the following steps: under normal pressure, with a laser power of 1 kW to 3 kW and in a quasi-focused state, the laser acts on the weld for 100 ms to 500 ms, and the spot fixation is completed. Others are the same as in Specific Embodiments 1 to 5.

[0054] During the spot fixation process of this specific embodiment, neither the welded part nor the laser head moves. The laser emits light successively at the positions at both ends of the weld, locally melts, forms a small molten pool, stops after 200 ms, and the spot fixation on the upper surface is completed. The same method is used for the spot fixation on the lower surface.

[0055] Specific Embodiment 7: The difference between this embodiment and any one of Specific Embodiments 1 to 6 is that: during the spot fixation process in Step 1, neither the welded part nor the laser head moves. Others are the same as in any one of Specific Embodiments 1 to 6.

[0056] Specific Embodiment 8: The difference between this embodiment and any one of Specific Embodiments 1 to 7 is that: the vacuum environment pressure in Step 2 is 0.1 Pa to 10 kPa, and the argon atmosphere is adjusted according to the following steps: First, turn on the mechanical pump. When the vacuum environment pressure drops below 16 kPa, turn on the Roots pump. When the vacuum environment pressure reaches 0.1 Pa to 10 kPa, introduce argon with a pressure of 0.2 kPa to 3 kPa for 0.1 min to 3 min. The vacuum environment pressure rises, and the argon intake is adjusted downward until the vacuum environment pressure reaches 0.1 Pa to 10 kPa again, and the pumping speed of the vacuum pump is balanced with the charging speed, and the chamber environment pressure is constant. Others are the same as in Specific Embodiments 1 to 7.

[0057] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that: Step 2 sequentially closes the Roots pump and the mechanical pump, then opens the air inlet valve to allow air to enter the cabin, and after the pressure in the cabin is consistent with the external environment pressure, the cabin door is opened to take out the weldment. The rest is the same as specific embodiments 1 to 8.

[0058] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that: in step 2, a single laser is used to center the welding laser spot on the center line of the weld without offset. The rest is the same as specific embodiments 1 to 9.

[0059] The following examples are used to verify the beneficial effects of the present invention:

[0060] Embodiment 1, combined with Figure 1 Specific instructions:

[0061] A low vacuum laser welding method for electroformed nickel / GH4169 high temperature alloy is carried out according to the following steps:

[0062] 1. Weldment assembly:

[0063] Use acetone to wipe the surfaces of electroformed nickel and GH4169 to be welded, remove surface oil, moisture and impurities, assemble the electroformed nickel and GH4169 to achieve a bottom-locked butt joint, use a clamp to fix the butt surfaces to fit tightly, then under normal pressure, laser power of 2kW and quasi-focus, apply laser to one side of the weld for 200ms to achieve spot fixation at both ends of the weld, then repeat the operation to achieve spot fixation at both ends of the weld on the other side, remove the clamp after spot fixation, place the spot-fixed weldment on the low-vacuum laser welding platform in the vacuum chamber, and clamp and fix it;

[0064] 2. Low vacuum laser welding:

[0065] Under the conditions of vacuum environment pressure of 0.2kPa, argon atmosphere, laser power of 2.8kW, laser beam incident angle of 90°, spot diameter of 0.4mm, welding speed of 0.9m / min and defocus of -2mm, a single laser is used to center the welding laser spot on the center line of the weld without offset, and the laser head moves along the welding path to form a weld. After welding, the weldment is cooled in a low vacuum environment, the Roots pump and the mechanical pump are turned off in turn, and then the air inlet valve is opened to allow air to enter the cabin. After the internal pressure of the cabin is consistent with the external environment pressure, the cabin door is opened and the weldment is taken out, thus completing the low vacuum laser welding method of electroformed nickel / GH4169.

[0066] The thickness of the electroformed nickel and GH4169 described in step 1 is both 6 mm.

[0067] The lock bottom width of the lock bottom butt joint described in step 1 is 3.5 mm, and the lock bottom depth is 4 mm.

[0068] During the spot welding process in Step 1, neither the welded part nor the laser head moves.

[0069] The so-called focusing in Step 1 specifically means that the distance from the laser head to the surface of the welded part is the focal length (300 mm), and at this time, the spot diameter is the smallest.

[0070] The pressure of the vacuum environment in Step 2 is 0.2 kPa, and the argon atmosphere is adjusted according to the following steps: First, turn on the mechanical pump. When the pressure of the vacuum environment drops below 16 kPa, turn on the roots pump. When the pressure of the vacuum environment reaches 0.2 kPa, introduce argon with a pressure of 1.5 kPa for 0.5 min. The pressure of the vacuum environment rises, and then adjust the argon intake volume until the pressure of the vacuum environment reaches 0.2 kPa again, so that the pumping speed of the vacuum pump is balanced with the inflation speed, and the pressure of the chamber environment is constant.

[0071] Figure 1 It is a schematic diagram of the low-vacuum laser welding method for electroformed nickel / GH4169 in Example 1. 1 is a 10 kW fiber laser, 2 is a 200 μm optical fiber, 3 is a vacuum chamber, 4 is a laser head, 5 is a roots pump, 6 is a mechanical pump, 7 is a low-vacuum laser welding platform, 8 is a welded part, and 9 is the welding direction. Among them, the 10 kW fiber laser is produced by IPG Corporation, and the laser and the laser head are connected by a 200 μm optical fiber to transmit the laser from the laser to the laser head. The mechanical pump, the roots pump and the vacuum chamber are connected by pipelines, and the connection sequence is that the vacuum chamber is connected to the roots pump, and the roots pump is connected to the mechanical pump. The welded part is fixed on the welding workbench by a fixture, and the welded part remains fixed during the welding process, that is, the welding is achieved by the movement of the laser head. The laser head moves along the welding direction at the welding speed, and the welding speed, defocus amount and offset amount are all achieved by the three-axis movement of the laser head. At the same time, a water cooling system is configured to be responsible for the cooling of the 10 kW laser and the laser head. The water circuits for the cooling of the laser and the laser head are independent cycles, which can effectively ensure the cooling effect of the device.

[0072] Example 2: The difference between this example and Example 1 is as follows: In Step 1, the thickness of the electroformed nickel is 10 mm, and the thickness of GH4169 is 15 mm; in Step 1, the lock bottom width of the lock bottom butt joint is 4 mm, and the lock bottom depth is 10 mm; in Step 2, under the conditions of a vacuum environment pressure of 0.2 kPa, an argon atmosphere, a laser power of 4 kW, a laser beam incident angle of 90°, a spot diameter of 0.4 mm, a welding speed of 0.6 m / min and a defocus amount of -5 mm, use a single laser to center the welding laser spot on the center line of the weld without an offset amount, and the laser head moves along the welding path to form a weld. Others are the same as in Example 1.

[0073] Example 3: The differences between this example and Example 1 are as follows: In Step 1, the thickness of the electroformed nickel is 10 mm and the thickness of GH4169 is 15 mm; the bottom width of the lock-bottom butt joint described in Step 1 is 4 mm and the bottom depth is 10 mm; in Step 2, under the conditions of a vacuum environment pressure of 0.2 kPa, an argon atmosphere, a laser power of 4.2 kW, a laser beam incident angle of 90°, a spot diameter of 0.4 mm, a welding speed of 0.6 m / min, and a defocus amount of -5 mm, a single laser is used to center the welding laser spot on the center line of the weld seam without an offset amount, and the laser head moves along the welding path to form the weld seam. Others are the same as in Example 1.

[0074] Figure 5 Figure 4 shows the physical diagrams of the surface morphology and cross-sectional morphology of the welded part after welding in Example 1. a is the surface morphology and b is the cross-sectional morphology. As can be seen from the figure, the weld seam is well formed, the metals on both sides of the weld seam are melted, there are no defects such as cracks and pores inside the weld seam, the penetration depth of the weld seam is 5.1 mm, the width is 2.84 mm, and the depth-width ratio is 1.8:1.

[0075] Figure 6 Figure 8 shows the physical diagrams of the surface morphology and cross-sectional morphology of the welded part after welding in Example 2. a is the surface morphology and b is the cross-sectional morphology. As can be seen from the figure, the weld seam is well formed, the metals on both sides of the weld seam are evenly melted, there are no defects such as cracks and pores inside the weld seam, the penetration depth of the weld seam is 11.26 mm, the width is 2.93 mm, and the depth-width ratio is 3.8:1.

[0076] Figure 7 Figure 12 shows the element distribution diagram of the Ni side of the welded joint of the welded part in Example 2. As can be seen from the figure, the Ni side joint is well fused, there are no unfused defects and cracks, and the element transition at the fusion line is gentle, avoiding the attenuation of mechanical properties caused by element mutation.

[0077] Figure 8 Figure 16 shows the physical diagrams of the surface morphology and cross-sectional morphology of the welded part after welding in Example 3. a is the surface morphology and b is the cross-sectional morphology. As can be seen from the figure, the weld seam is well formed, the metals on both sides of the weld seam are evenly melted, there are no defects such as cracks and pores inside the weld seam, the depth of the weld seam is 12.41 mm, the width is 2.98 mm, and the depth-width ratio is 4.2:1.

Claims

1. A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy, characterized in that It is carried out according to the following steps: I. Weldment assembly: The electroformed nickel and GH4169 are assembled to make the butt surfaces fit tightly, and then laser spot welding is carried out. The spot-welded weldment is fixed on the low-vacuum laser welding platform in the vacuum chamber; The thickness of the electroformed nickel is 10 mm, and the thickness of the GH4169 is 15 mm; The assembly of the electroformed nickel and GH4169 realizes a lock-bottom butt joint, with a lock-bottom width of 4 mm and a lock-bottom depth of 10 mm; II. Low-vacuum laser welding: Under the conditions of a vacuum environment pressure of 0.2 kPa, an argon atmosphere, a laser power of 4.0 kW, a laser beam incident angle of 90°, a spot diameter of 0.4 mm, a welding speed of 0.6 m / min, and a defocus amount of -5 mm, the welding laser spot is centered on the center line of the weld seam without an offset. The laser head moves along the welding path to form a weld seam. After welding is completed, the weldment is cooled in a low-vacuum environment, and the weldment is taken out, thus completing the low-vacuum laser welding method of electroformed nickel / GH4169.

2. The low-vacuum laser welding method of electroformed nickel / GH4169 superalloy according to claim 1, characterized in that The electroformed nickel and GH4169 described in step I are the electroformed nickel and GH4169 after acetone cleaning.

3. The low-vacuum laser welding method of electroformed nickel / GH4169 superalloy according to claim 1, characterized in that The laser spot welding described in step I is specifically carried out according to the following steps: Under normal pressure, a laser power of 2 kW, and a condition of being in focus, the laser acts on the weld seam for 200 ms to complete the spot welding.

4. A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy according to claim 3, characterized in that During the spot welding process in step I, neither the weldment nor the laser head moves.

5. A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy according to claim 1, characterized in that The vacuum environment pressure of 0.2 kPa and the argon atmosphere described in step II are adjusted according to the following steps: First, turn on the mechanical pump. When the vacuum environment pressure drops below 16 kPa, turn on the Roots pump. When the vacuum environment pressure reaches 0.2 kPa, introduce argon with a pressure of 1.5 kPa for 0.5 min. The vacuum environment pressure rises, and the argon intake is adjusted downward until the vacuum environment pressure reaches 0.2 kPa again, and the pumping speed of the vacuum pump is balanced with the inflation speed, and the chamber environment pressure is constant.

6. The low-vacuum laser welding method of electroformed nickel / GH4169 superalloy according to claim 5, characterized in that In step II, turn off the Roots pump and the mechanical pump in sequence, then open the intake valve, air enters the chamber, and after the pressure in the chamber is the same as the external environment pressure, open the chamber door and take out the weldment.

7. A low-vacuum laser welding method for electroformed nickel / GH4169 superalloy according to claim 1, characterized in that In step II, a single laser is used to center the welding laser spot on the center line of the weld seam without an offset.

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