Electron beam welding method for radial welding seam of high-strength material
Through large interference coordination, laser cleaning and post-weld insulation and slow cooling, the problem of cracks and defects in welding of high-strength materials is solved, and the reliability and quality of the welds are improved.
Patent Information
- Application Number
- CN202510754023.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-06
- Publication Date
- 2025-07-25
AI Technical Summary
High-strength materials are prone to cracks and difficult to weld during welding, especially large-thick radial welds, and there is a risk of defects such as pores and slag inclusions, which affects the welding quality.
The large interference combination design is used to offset the welding tensile stress, the laser cleaning equipment is used to remove oxide layers and impurities, the post-weld insulation and cooling process reduces residual stress, the segmented welding strategy reduces stress differences, and combines visual, ray and fluorescence detection to ensure defect elimination.
It effectively suppresses the occurrence of cracks, reduces the probability of defects such as pores and slag inclusions, and improves the mechanical properties and yield of the welds.
Smart Images
Figure CN120362683A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of high-strength material welding, and specifically relates to an electron beam welding method for radial welds of high-strength materials. Background Art
[0002] As Figure 1 and Figure 2 shown, the combustion chamber casing of a certain aeroengine is formed by electron beam welding of an inner casing and an outer casing. The welding material is a newly developed superalloy GH4251, which has high strength, high temperature resistance, but poor plasticity. Therefore, while improving the service temperature and high temperature strength of the parts, it inevitably reduces the welding performance of the alloy. On the one hand, the thermal stress generated during the electron beam welding process will cause plastic deformation and shrinkage of the material. Materials with poor plasticity have a small shrinkage amount during welding, the deformation of the welded parts is small, but the internal stress is large, and the residual stress of the weld is also large, making cracks more likely to occur. At the same time, if welding defects such as pores and slag inclusions occur, the risk of repair welding is also relatively high. On the other hand, for large-thickness radial welds, the welding difficulty is great. Therefore, how to select appropriate welding parameters, formulate welding methods according to the characteristics of the parts to reduce the generation of welding stress and welding defects, control the number of reworks, and improve the welding quality of the welds is of great significance. Summary of the Invention
[0003] The present invention provides an electron beam welding method for radial welds of high-strength materials, which solves the problems of large internal stress, more prone to cracks and great welding difficulty during combustion chamber welding.
[0004] To achieve the above object, the present invention provides the following technical solutions: An electron beam welding method for radial welds of high-strength materials, comprising: Design the welding joint of the inner casing and the outer casing as a large interference fit, and generate pre-compressive stress through pre-welding assembly to offset the welding tensile stress; Use a laser cleaning device to clean the weld joint to be welded, and perform welding after cleaning; After welding, put the parts into a heating furnace for heat preservation, and then cool them with the furnace; Determine the welding parameters, and perform seal welding and formal welding in sequence. The seal welding starts from the 0° position of the part, and the formal welding starts from the 180° position of the part; Visually inspect, radiographically inspect and fluorescently inspect the weld to ensure no cracks, lack of fusion, lack of penetration and excessive porosity defects.
[0005] Preferably, the large interference fit is achieved by the following method: Heat the outer casing to 180°C and keep it warm for 1 - 1.5 hours, and assemble the outer casing with the inner casing after it expands.
[0006] Preferably, the welding parameters include a welding speed of 900 mm / min, an accelerating voltage of 150 kV, a seal welding current of 7.0 mA, and a formal welding current of 15.0 mA.
[0007] Preferably, the welding speed for seal welding is 960 mm / min, the arc starting angle is 0°, and the arc is terminated after maintaining at 5°; The welding speed for formal welding is 960 mm / min, the arc starting angle is 180°, and the arc is terminated after maintaining at 20°.
[0008] Preferably, welding shall be carried out within 24 hours after cleaning.
[0009] Preferably, after welding, the parts are placed in a heating furnace, kept at 180 - 200 °C for 1 - 1.5 hours, and then cooled with the furnace.
[0010] Preferably, cleaning the joint to be welded also includes using acetone to clean the parts and fixtures, removing oil stains, and wiping the area of the joint to be welded with a silk cloth dipped in acetone.
[0011] Preferably, seal welding and formal welding are performed in sequence under an environment with a vacuum degree ≤ 6×10 -4 bar.
[0012] Preferably, the weld seam is a radial weld seam of the combustion chamber casing.
[0013] Preferably, the requirements for ray detection are that there are no sharp - angled and linear pores and slag inclusions inside the weld seam, and the pore size does not exceed the standard allowable value.
[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an electron beam welding method for a radial weld seam of high - strength materials. By designing the welding joint of the inner casing and the outer casing to be a large interference fit, the pre - compressive stress generated by pre - assembly before welding effectively offsets the horizontal tensile stress caused by heat input during the welding process, thereby suppressing the crack risk of high - strength materials with poor plasticity due to stress concentration. Using a laser cleaning device to clean the joint to be welded can efficiently remove the oxide layer and impurities, reducing the generation probability of defects such as pores and slag inclusions. After welding, through the heat - preservation and slow - cooling process, the residual stress in the welding area is promoted to be slowly released, while avoiding the formation of brittle and hard tissues, improving the mechanical properties of the weld seam. During the welding process, a segmented welding strategy is adopted to reduce the solidification shrinkage stress of the molten pool and the differential stress in the heat - affected zone. Finally, through multi - level quality control means such as visual inspection, ray detection, and fluorescence detection, it is ensured that there are no cracks, lack of fusion, incomplete penetration, and over - standard pore defects on the inner and outer surfaces and inside the weld seam, significantly improving the welding reliability and finished product rate of the large - thickness radial weld seam of high - strength materials. Description of the Drawings
[0015] Figure 1 It is a drawing of a certain aero - engine combustion chamber casing in the background technology of the present invention; Figure 2 This is a schematic diagram of the area to be welded on the combustion chamber casing of an aeroengine in the background art of the present invention; Figure 3 This is a flowchart of an electron beam welding method for a radial weld of a high-strength material according to the present invention; In the figure, 1 - inner casing, 2 - outer casing, 3 - area to be welded. Specific embodiments
[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.
[0017] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.
[0018] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.
[0019] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.
[0020] As Figure 3 shown, the present invention provides an electron beam welding method for a radial weld of a high-strength material, including: S1 Design the welding joint of the inner casing and the outer casing as a large interference fit, and generate pre-compressive stress through pre-assembly before welding to offset the welding tensile stress; S2 Use a laser cleaning device to clean the welding joint, and perform welding after cleaning; S3 After welding, place the part in a heating furnace for heat preservation, and then cool it in the furnace; S4 Determine the welding parameters, and perform seal welding and formal welding in sequence. The seal welding starts at the 0° position of the part, and the formal welding starts at the 180° position of the part; S5 Perform visual inspection, radiographic inspection, and fluorescent inspection on the weld to ensure that there are no cracks, lack of fusion, incomplete penetration, and excessive porosity defects.
[0021] The specific design of the joint structure is as follows: Radial welds generate tensile stress in the horizontal direction during welding. When the tensile stress is greater than the yield strength, cracks perpendicular to the welding direction will occur on the weld. The yield strength of GH4251 material is relatively low. To prevent cracks from occurring during welding, the joint fitting method is designed as a large interference fit. Before welding, a certain amount of compressive stress is pre-generated on the weld part of the parts to offset part of the tensile stress generated during welding, thereby reducing the tensile stress and inhibiting crack generation. Considering that the electron beam current is relatively narrow and shaped like an inverted funnel, if there is slight deformation in the welded joint, incomplete fusion is likely to occur at the root of the weld, and a complete circle of linear display along the weld direction will appear during radiographic inspection after removing the lock bottom. Therefore, the thickness of the welding stop should be slightly larger to ensure that it can contain the depth of the incomplete fusion weld. After testing, the stop thickness is determined to be 2 mm.
[0022] The specific welding parameters are determined as follows: The stress that causes deformation of the parts comes from two aspects. On the one hand, it comes from the shrinkage stress generated by metal fusion and solidification. The wider the weld, the greater the shrinkage stress. On the other hand, the stress comes from the difference in the welding affected zones above and below the weld. The greater the width difference of the zone, the greater the stress generated. Therefore, to reduce the welding width and heat input, the focusing method is determined to be surface focusing, and no deflection is added to the beam current, and no dressing weld and tack weld are carried out.
[0023] The heat input also directly affects the magnitude of the stress generated by welding, and its magnitude is determined by the welding parameters. Heat input is defined as the ratio of welding power (Q) to welding speed (V). Among them, η is the efficiency of power transfer. As can be seen from formula (1), the welding speed is inversely proportional to the heat input. Therefore, the welding speed should not be too fast. To improve the weld quality and reduce the vaporization and discharge of welding defects such as pores and slag inclusions, the welding speed also needs to be slowed down. After experimental verification, when the welding speed is selected as 900 mm / min, the weld formation is good and the weld quality is high; HI = ηQ / V (1).
[0024] The specific pre-welding cleaning is as follows For the defects generated by electron beam welding, local repair welding is generally carried out using argon arc welding. Due to the high strength of GH4251 material, the heat input generated by argon arc welding is large and stress concentration is more likely to cause weld cracking. Therefore, it is necessary to avoid defects such as pores and slag inclusions as much as possible. Since the defects are not easy to repair, a laser cleaning device is used to clean the welded joint before welding, and electron beam welding needs to be carried out within 24 hours after cleaning.
[0025] The specific post-welding treatment is as follows: Slow cooling after welding can reduce the residual stress of the welded joint and prevent the appearance of brittle and hard tissues. At the same time, post-weld post-heating is increased. After the parts are placed in a heating furnace and kept at 180 - 200 °C for 1 - 1.5 hours, they are cooled with the furnace.
[0026] Another embodiment of the present invention provides an electron beam welding method for radial welds of high-strength materials, including: Step 1. Clean the parts and fixtures. Clean the parts and welding fixtures with acetone to remove oil stains, and wipe the area of the joint to be welded with a silk cloth dipped in acetone.
[0027] Step 2. Thermal assembly Put the outer casing parts into an oven for heating. After continuously heating at 180°C for 1 hour, assemble the expanded outer casing with the inner casing to ensure an interference fit between the parts.
[0028] Step 3. Pre-welding dimensional inspection Assemble the parts as required, and use a coordinate measuring machine to detect the circumferential runout of the parts and the circular runout at the weld to check whether it is within the standard range. If not meeting the requirements, the parts need to be disassembled, reassembled, and corrected until the requirements are met.
[0029] Step 4. Electron beam welding. The welding parameters are shown in Table 1, where the accelerating voltage is 150 KV at high voltage.
[0030] Horizontally install the assembled components and welding fixtures on the tiltable rotary table of the electron beam welding machine, and evacuate to ≤6×10 -4 bar.
[0031] Use a longitudinal electron gun for the welding machine, set the tilt angle of the welding machine turntable to 0°, use a small beam current to measure points after finding the weld position, perform sealing welding starting from 0° of the part, and perform formal welding starting from 180° of the part, welding 370°.
[0032] Table 1 Welding parameters
[0033] Step 5. Post-welding slow cooling and post-heating After welding, keep warm for 5 minutes to release gas, put it into an oven, continuously heat at 180°C for 1 hour, and then cool with the furnace.
[0034] Step 6. Visual inspection Visually inspect the electron beam welds according to the standard. It is required that the weld surface should be smooth and smoothly transition to the base metal, and there should be no visually visible defects such as cracks, lack of fusion, incomplete penetration, burn, burn-through, etc. After welding the parts using the above steps, the visual inspection of the welds is qualified.
[0035] Step 7. Radiographic inspection and fluorescent inspection Perform radiographic inspection and fluorescent inspection on the welds according to the standard. It is required that there should be no defects such as cracks, lack of fusion, and incomplete penetration inside the welds. Angular and linear pores, slag inclusions, and excessive pores are not allowed.
[0036] After welding the parts using the above steps, both the radiographic inspection and the fluorescent inspection of the weld seam show qualified results.
[0037] Another embodiment of the present invention provides an electron beam welding method for the radial weld seam of a high-strength material, including: Step 1: Preparation before welding Clean the parts and fixtures: Use acetone to clean the oil stains on the surfaces of the inner casing, outer casing, and fixtures, and wipe the area to be welded with a silk cloth dipped in acetone.
[0038] Laser cleaning: Use a laser device to clean the weld seam area, remove the oxide layer and impurities, and complete the welding within 24 hours after cleaning.
[0039] Step 2: Hot fitting and assembly Heat the outer casing: Place the outer casing in an oven, keep it at 180°C for 1 hour to make it expand, and then assemble it with the inner casing to form a large interference fit.
[0040] Dimensional inspection: Use a coordinate measuring machine to detect the circular runout error after assembly, ensure that it is ≤0.05mm, and if it exceeds, re-calibrate.
[0041] Step 3: Electron beam welding Vacuum environment: Fix the assembled body on the turntable of the electron beam welding machine, evacuate to 6×10 -4 bar.
[0042] Welding parameters: Seal welding: Start arc at 0°, current 7.0mA, speed 960mm / min, keep for 5° after welding 10°.
[0043] Formal welding: Start arc at 180°, current 15.0mA, speed 960mm / min, weld in a range of 370°.
[0044] Focusing method: Surface focusing, no beam deflection.
[0045] Step 4: Post-welding treatment Slow cooling: Keep warm for 5 minutes after welding to release gas, then place the parts in an oven, keep at 180°C for 1 hour and then cool down to room temperature with the furnace.
[0046] Step 5: Weld seam inspection Visual inspection: The weld seam surface is smooth, without cracks, lack of fusion, and burn-through.
[0047] Radiographic inspection: There are no linear porosity, slag inclusions, and lack of penetration defects inside, and the pore diameter is ≤0.3mm.
[0048] Fluorescent inspection: There are no surface micro-cracks.
[0049] Although the embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments and application fields. The above specific embodiments are merely illustrative and guiding, rather than restrictive. Under the inspiration of the specification, those of ordinary skill in the art can also make many forms without departing from the scope protected by the claims of the present invention, and all of these fall within the scope of protection of the present invention.
Claims
1. An electron beam welding method for a radial weld of a high-strength material, characterized in that Including: Design the welded joint of the inner casing and the outer casing as a large interference fit, and generate pre-compressive stress through pre-assembly before welding to offset the welding tensile stress; Use a laser cleaning device to clean the joint to be welded, and then perform welding after cleaning; After welding, put the parts into a heating furnace for heat preservation, and then cool them in the furnace; Determine the welding parameters, and perform seal welding and formal welding in sequence. The seal welding starts at the 0° position of the part, and the formal welding starts at the 180° position of the part; Conduct visual inspection, radiographic testing and fluorescent testing on the weld to ensure no cracks, lack of fusion, incomplete penetration and excessive porosity defects.
2. The electron beam welding method for the radial weld of a high-strength material according to claim 1, characterized in that, The large interference fit is achieved by the following method: Heat the outer casing to 180°C and keep it warm for 1 - 1.5 hours, and then assemble the outer casing with the inner casing after it expands; 3. The electron beam welding method for the radial weld of a high-strength material according to claim 1, characterized in that, The welding parameters include a welding speed of 900 mm / min, an accelerating voltage of 150 kV, a seal welding current of 7.0 mA and a formal welding current of 15.0 mA.
4. The electron beam welding method for the radial weld of a high-strength material according to claim 1, characterized in that, The welding speed of the seal welding is 960 mm / min, the starting arc angle is 0°, and the arc is stopped after maintaining for 5°; The welding speed of the formal welding is 960 mm / min, the starting arc angle is 180°, and the arc is stopped after maintaining for 20°; 5. The electron beam welding method for the radial weld of a high-strength material according to claim 1, characterized in that Welding shall be carried out within 24 hours after cleaning.
6. The electron beam welding method for the radial weld of a high-strength material according to claim 1, characterized in that, After welding, put the parts into a heating furnace, keep them warm at 180 - 200°C for 1 - 1.5 hours, and then cool them in the furnace; 7. An electron beam welding method for a radial weld of a high-strength material according to claim 1, characterized in that, Cleaning the joint to be welded also includes using acetone to clean the parts and fixtures to remove oil stains, and wiping the area of the joint to be welded with a silk cloth dipped in acetone.
8. The electron beam welding method for the radial weld of a high-strength material according to claim 1, characterized in that Perform sealing welding and formal welding in sequence under the environment with a vacuum degree ≤ 6×10 -4 bar.
9. The electron beam welding method for the radial weld of a high-strength material according to claim 1, characterized in that, The weld is the radial weld of the combustion chamber casing.
10. The electron beam welding method for the radial weld of a high-strength material according to claim 1, characterized in that, The requirements for radiographic testing are that there are no sharp-angle and linear pores and slag inclusions inside the weld, and the pore size does not exceed the standard allowable value.