Method and part for eliminating local chain-shaped pore defect of beam slope attenuation area

Abstract

The invention discloses a method and part for eliminating local chain-shaped pore defects in a beam slope attenuation area, and belongs to the technical field of electron beam welding.The method includes the steps that in the formal welding stage of a workpiece to be welded, stable welding is conducted for more than one complete circle, and then the beam attenuation process is started; in the beam attenuation process, the beam is controlled to be reduced to a zero value in a linear attenuation mode; when beam attenuation of the to-be-welded workpiece is started, a focusing current value is synchronously and progressively increased, so that the focus position of an electron beam gradually moves upwards from the surface of a connector; and when the beam current drops to a zero value and the focusing current value reaches a preset incremental quantity, performing local modification welding on a beam current attenuation area of the to-be-welded workpiece so as to eliminate the local chain-shaped pore defect of the beam current slope attenuation area and finish the welding of the to-be-welded workpiece. According to the method, the problem that local chain-shaped air hole defects of beam attenuation areas are prone to occurring in the welding process of nitrogen-containing stainless steel and other workpieces difficult to weld can be effectively solved, and the welding quality and the qualification rate of parts can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of electron beam welding, and in particular relates to a method and parts for eliminating local chain-shaped pore defects in a beam slope attenuation zone. Background Art

[0002] Electron beam welding (EBW) is widely used in aviation manufacturing due to its advantages, including high power density, minimal welding distortion, and high precision. During EBW, the molten metal in the weld pool flows backward, in the opposite direction of the weld. If a high beam current is applied directly at the start of welding to maintain a stable weld and then discontinued at the end, the weld will produce an excessively high weld reinforcement at the start and a deep crater at the end. This defect must be avoided in actual component welding, otherwise the weld quality will fail to meet acceptance standards.

[0003] For straight welds, this defect is typically addressed by adding lead-in and lead-out plates made of the same material as the component at both ends of the weld. These plates direct the electron beam into and out of the weld, retaining the weld reinforcement at the start and the pit at the end of the weld on the lead-in and lead-out plates and ultimately removing them. However, for girth welds, these lead-in and lead-out plates are not suitable. Instead, the weld reinforcement and pit at the end of the weld are eliminated by gradually increasing the beam current to a stable welding current at the start of welding (beam ramping) and then gradually reducing the stable welding current to zero at the end of welding (beam decay). During the girth weld process, the dynamic conditions of the weld pool constantly change in the beam ramping and beam decaying regions, leading to extremely unstable pressure in the weld pool vapor chamber, which can easily lead to chain porosity defects within the weld. When welding girth welds, in order to ensure complete penetration of the weld joint around the entire circumference of the weld, a welding overlap occurs. After the overlap ends, the beam begins to decay, and the electron beam current gradually decreases. The pressure and dynamic conditions of the weld pool vapor chamber change, which can easily lead to local chain porosity defects in the weld. Metals such as titanium alloys and high-temperature alloys are not very sensitive to local chain porosity defects in the beam decay region. However, for some nitrogen-containing stainless steel materials, local chain porosity defects in the beam decay region are one of the most common defects in parts, making the beam decay region a relatively difficult area to weld in the girth weld. In summary, in current electron beam welding, especially during girth weld welding, the pressure of the weld pool vapor chamber becomes extremely unstable due to the increasing beam current and the changes in the dynamic conditions of the weld pool in the beam decay region, which can easily lead to chain porosity defects in the weld, reducing the welding quality of the parts. Summary of the Invention

[0004] The present invention provides a method and parts for eliminating local chain-shaped pore defects in the beam slope attenuation zone, aiming to solve the problem that in current electron beam welding, especially in the welding process of girth welds, the pressure of the molten pool steam chamber is extremely unstable due to the increase of beam current and the change of dynamic conditions of the welding pool in the beam attenuation zone, which leads to the easy generation of chain-shaped pore defects inside the weld and reduces the welding quality of the parts.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for eliminating local chain-shaped air hole defects in a beam slope attenuation zone, comprising the following steps: S1. During the formal welding phase of the workpiece to be welded, first perform stable welding on the workpiece for more than one full week, and then start the beam decay process; S2. During the beam attenuation process of the workpiece to be welded, the beam is controlled to decrease to zero in a linear attenuation manner; S3, while starting the beam attenuation of the workpiece to be welded, synchronously increasing the focus current value, so that the electron beam focus position gradually moves upward from the joint surface of the workpiece to be welded; S4. When the beam current drops to zero and the focusing current value reaches a predetermined increment, local modification welding is performed on the beam attenuation area of ​​the workpiece to be welded, so as to eliminate the local chain-like porosity defects in the beam slope attenuation area and complete the welding of the workpiece to be welded.

[0006] In some embodiments, in S1, during more than one full cycle of stable welding, the angle range of stable welding is controlled to be ~ .

[0007] In some embodiments, in S2, during the beam attenuation process of the workpiece to be welded: The angle range corresponding to the beam attenuation process is controlled as follows: ~ ; The linear decay rate of the beam is controlled to be 3mA / s~6mA / s.

[0008] In some embodiments, in S3 , the increasing amount of the focusing current value is controlled to be 30 mA to 60 mA.

[0009] Furthermore, in S3, the focusing current value increases at a constant rate, and the increasing process is completed synchronously with the linear decay of the beam current.

[0010] In some embodiments, the material of the workpieces to be welded includes stainless steel containing nitrogen.

[0011] In some embodiments, the workpiece to be welded includes an annular workpiece, and the diameter of the weld seam of the annular workpiece is controlled to be 600 mm to 1500 mm.

[0012] In some embodiments, in S4, when performing local modification welding, the welding area of ​​the local modification welding covers the weld area corresponding to the beam attenuation.

[0013] The present invention also provides a part, which is welded by eliminating the local chain-shaped pore defects in the beam slope attenuation area.

[0014] Compared with the prior art, the method and parts of the present invention for eliminating local chain-shaped pore defects in the beam slope attenuation zone have the following beneficial effects: The present invention provides a method for eliminating local chain-like porosity defects in the beam slope attenuation zone. To ensure that the weld joint of a part is fully melted throughout the entire circumference of the weld, the overlapping area is welded. After the part rotates one circle, welding will continue for a certain length to completely remelt the beam increasing area. At this time, not only can the full melt of the weld of the part be ensured throughout the entire circumference, but also the local chain-like porosity defects that may be generated in the beam increasing area can be eliminated. By starting beam attenuation after ultra-stable welding, the beam linearly decays to zero, and the beam attenuation synchronously increases the focusing current. After the beam returns to zero, a local modification welding is performed on the attenuation area to ensure that the weld is fully melted throughout the entire circumference and avoid unfused defects. The present invention stabilizes the molten pool vapor pressure by controlling the linear attenuation rate, slows down the molten pool solidification rate by controlling the focus upward and reducing the energy, thereby reducing the resistance of the porosity escape, and finally repairs the potential defects in the attenuation area in a targeted manner to completely eliminate the chain-like porosity.

[0015] The present invention can relatively thoroughly eliminate the problem of localized chain-like porosity defects caused by dynamic changes in the electron beam molten pool vapor chamber in the beam attenuation region during electron beam welding of girth welds, thereby ensuring component welding quality. Furthermore, the present invention can avoid the occurrence of localized solidification cracks in the weld caused by excessive beam attenuation, thereby forming a defect-free electron beam weld. This method is particularly effective for difficult-to-weld materials such as nitrogen-containing stainless steel, which are prone to localized chain-like porosity defects in the beam attenuation region. By employing the method of the present invention, component welding quality and pass rate, as well as workpiece strength, can be significantly improved, possessing considerable practical significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings in the specification are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0017] Figure 1 The present invention is a method for eliminating local chain-shaped porosity defects in the beam slope attenuation zone and a flow chart of the method in parts. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0019] 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 invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0020] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0021] In the description of the embodiments of the present invention, it should be noted that if the terms "upper," "lower," "horizontal," "inner," etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is typically placed when in use. These terms are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0022] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0023] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0024] How to effectively improve the quality of electron beam welding of parts, especially parts made of nitrogen-containing stainless steel, and increase the product qualification rate.

[0025] like Figure 1 As shown, the present invention provides a method for eliminating local chain-shaped air hole defects in the beam slope attenuation zone, comprising the following steps: S1. During the formal welding phase of the workpiece to be welded, first perform stable welding on the workpiece for more than one full week, and then start the beam decay process; S2. During the beam attenuation process of the workpiece to be welded, the beam is controlled to decrease to zero in a linear attenuation manner; S3, while starting the beam attenuation of the workpiece to be welded, synchronously increasing the focus current value, so that the electron beam focus position gradually moves upward from the joint surface of the workpiece to be welded; S4. When the beam current drops to zero and the focusing current value reaches a predetermined increment, local modification welding is performed on the beam attenuation area of ​​the workpiece to be welded, so as to eliminate the local chain-like porosity defects in the beam slope attenuation area and complete the welding of the workpiece to be welded.

[0026] The present invention's method for eliminating localized chain-like porosity defects in the beam slope decay zone begins with more than one full cycle of stable welding at the start of formal welding. This ensures complete penetration of the initial weld and provides a stable welding environment for the subsequent beam decay phase. Stable welding preheats the weld area, reduces welding stress, and promotes uniform weld formation. After stable welding is completed, the welding beam decay begins. Unlike traditional methods of abruptly shutting off the beam, the present invention employs a linear decay method, allowing the beam current to steadily decrease at a linear rate until it reaches zero. This slow beam decay avoids drastic changes in the weld pool and reduces defects such as porosity and cracks. As the beam decay begins, the focusing current is simultaneously increased. This increase in focusing current gradually shifts the electron beam's focal point away from the joint surface of the workpieces being welded. This change in focal position helps maintain a stable weld pool and prevents pool collapse or porosity formation caused by beam decay. By precisely controlling the amount of focus current increase, the electron beam's focusing performance can be optimized, further improving weld quality. Finally, the present invention uses localized touch-up welding: Once the beam current drops to zero and the focusing current increases to a predetermined value, welding concludes. To ensure the final quality of the weld, localized touch-up welding is performed in the area where the beam current attenuates. This localized touch-up welding can further eliminate any minor defects, such as pores, cracks, or lack of fusion, thereby improving the overall quality and reliability of the weld.

[0027] Based on this, the method of the present invention for eliminating local chain-like pore defects in the beam slope attenuation zone can completely eliminate local chain-like pore defects in the beam slope attenuation zone through the synergistic effect of steps such as stable welding, slow beam attenuation, synchronous adjustment of the focusing current, and local modification welding, thereby significantly improving the welding quality. This method is particularly suitable for difficult-to-weld materials such as nitrogen-containing stainless steel, and can effectively solve the defect problems that are prone to occur in these materials during the welding process, thereby greatly improving the welding quality and pass rate of parts. Moreover, the present invention can avoid the occurrence of local solidification crack defects in the weld caused by too fast beam attenuation by slowly attenuating the beam and synchronously adjusting the focusing current, thereby ensuring the integrity and reliability of the weld, significantly enhancing the stability and controllability of the welding process, and helping to obtain more consistent and reliable welding results.

[0028] In some practical working conditions, the method of eliminating local chain-shaped porosity defects in the beam slope attenuation zone of the present invention is controlled to have a stable welding angle range of ~ By comprehensively controlling multiple parameters during the welding process, it is possible to completely eliminate local chain-like porosity defects in the beam slope attenuation zone and avoid the occurrence of local solidification crack defects in the weld, thereby significantly improving the welding quality.

[0029] The method of eliminating the local chain-shaped air hole defects in the beam slope attenuation zone of the present invention, in the beam attenuation process, the angle range corresponding to the beam attenuation process is controlled to be ~ The linear attenuation rate of the beam is controlled to be 3mA / s to 6mA / s. By precisely controlling the angle range and attenuation rate of the beam attenuation, the beam can be ensured to decay smoothly, avoiding the occurrence of local solidification crack defects in the weld due to excessive beam decay. It also helps to control the welding heat input and further improve the welding quality.

[0030] The method of the present invention for eliminating local chain-shaped porosity defects in the beam slope attenuation zone is as follows: during the beam attenuation process, the increasing amount of the focusing current value is controlled to be 30mA to 60mA. By synchronously increasing the focusing current value, the electron beam focal position is gradually moved upward from the joint surface of the workpiece to be welded, which helps to improve the molten pool morphology and fluidity during the welding process, thereby eliminating welding defects and improving welding quality.

[0031] During localized touch-up welding, the weld area of ​​the present invention covers the weld area corresponding to the beam attenuation. This localized touch-up welding can further eliminate any minor defects that may exist, improve the overall quality of the weld, ensure the integrity and reliability of the weld joint, and meet high-precision welding requirements.

[0032] The method disclosed herein for eliminating localized chain-like porosity defects in the beam slope decay zone is particularly suitable for workpieces made of nitrogen-containing stainless steel, effectively improving the quality of electron beam welding of parts, particularly those made of nitrogen-containing stainless steel. This method is particularly effective for difficult-to-weld materials such as nitrogen-containing stainless steel, which are prone to localized chain-like porosity defects in the beam slope decay zone. It can significantly improve welding quality and yield, while reducing production costs.

[0033] In some actual working conditions, the present invention is applicable to annular workpieces, especially workpieces with a weld diameter between 600 mm and 1500 mm, and helps to solve the defect problems of such workpieces during the welding process, thereby improving welding quality and production efficiency.

[0034] The present invention also provides a part, which is welded by eliminating local chain-shaped pore defects in the beam slope attenuation zone. Through the method of the present invention, the qualified rate of the processed parts is high and the quality is guaranteed.

[0035] The method and components for eliminating local chain-shaped air hole defects in the beam slope attenuation zone of the present invention are further described in detail below through specific embodiments.

[0036] The method of eliminating local chain-shaped pore defects in the beam slope attenuation zone of the present invention is specifically: 1) When the ring is formally welded, the stable welding is greater than Then the beam attenuation begins; 2) During the beam attenuation process, the beam attenuation rate is strictly controlled so that the beam current value decays linearly at a rate of 3mA / s to 6mA / s until the beam current value drops to 0mA; 3) As the beam current begins to decay, the focusing current value is changed synchronously, so that when the beam current decays to 0mA, the focusing current value gradually increases by 30mA to 60mA. At this time, the focal position of the electron beam gradually changes from the joint surface to a certain position above the joint surface. When the beam current value drops to 0mA and the focusing current increases to the specified value, the welding is officially completed.

[0037] 4) Perform local modification welding on the beam attenuation area to complete the parts welding.

[0038] Example 1 The workpiece to be welded is a circular weld part with a diameter of 1500mm at a certain weld seam. Then the beam current decayed. The decay rate of the beam current was set to 3mA / s. The beam current decayed to 0mA in 7 seconds (the beam current was converted to an angle of about The official welding is ended when the beam current decays to 0 mA. The focusing current is increased by 30 mA synchronously when the beam current starts to decay. The welding operation of the ring-shaped welding part with a diameter of 800 mm at the welding position is completed after the modification welding of the beam current decay region.

[0039] Example 2 The workpiece to be welded is a ring-shaped welding part with a diameter of 800 mm at the welding position. The stable welding is started The beam current decay is started after the stable welding. The decay rate of the beam current value is set to 6 mA / s, and the beam current decays to 0 mA in 5 seconds (converted into an angle, the beam current value is about The official welding is ended when the beam current decays to 0 mA. The focusing current is increased by 60 mA synchronously when the beam current starts to decay. The welding operation of the ring-shaped welding part with a diameter of 800 mm at the welding position is completed after the modification welding of the beam current decay region.

[0040] Example 3 The workpiece to be welded is a ring-shaped welding part with a diameter of 800 mm at the welding position. The stable welding is started The beam current decay is started after the stable welding. The decay rate of the beam current value is set to 5 mA / s, and the beam current decays to 0 mA in 3 seconds (converted into an angle, the beam current value is about The official welding is ended when the beam current decays to 0 mA. The focusing current is increased by 45 mA synchronously when the beam current starts to decay. The welding operation of the ring-shaped welding part with a diameter of 800 mm at the welding position is completed after the modification welding of the beam current decay region.

[0041] In summary, the method and the part for eliminating the local chain-shaped porosity defects in the beam current slope decay region effectively solve the technical problem of the local chain-shaped porosity defects in the beam current slope decay region in the electron beam welding by stable welding, linear beam current decay, synchronous adjustment of the focusing current and local modification welding. The welding parameters are accurately controlled in the method, such as the angle range of the stable welding, the beam current decay rate and the change amount of the focusing current, so as to ensure the stability of the welding process and the consistency of the welding quality. The present application is particularly suitable for difficult-to-weld materials such as nitrogen-containing stainless steel, and can significantly improve the welding quality and the qualification rate, and has good material adaptability. The present application covers the complete process of the welding process from the stable welding to the local modification welding, ensures the overall quality of the welding seam from the initial penetration to the final forming, and through the optimization of the welding process and the accurate control of the welding parameters, not only reduces the production cost, but also improves the welding quality and the production efficiency, Finally, it should be noted that the above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in this industry can smoothly implement the present invention as shown in the specification and described above. Any equivalent changes, modifications and evolutions made by using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A method for eliminating local chain-shaped pore defects in the beam slope attenuation zone, characterized in that: The steps include: S1. During the formal welding phase of the workpiece to be welded, first perform stable welding on the workpiece for more than one full week, and then start the beam decay process; S2. During the beam attenuation process of the workpiece to be welded, the beam is controlled to decrease to zero in a linear attenuation manner; S3, while starting the beam attenuation of the workpiece to be welded, synchronously increasing the focus current value, so that the electron beam focus position gradually moves upward from the joint surface of the workpiece to be welded; S4. When the beam current drops to zero and the focusing current value reaches a predetermined increment, local modification welding is performed on the beam attenuation area of ​​the workpiece to be welded, so as to eliminate the local chain-like porosity defects in the beam slope attenuation area and complete the welding of the workpiece to be welded.

2. The method for eliminating local chain-shaped pore defects in the beam slope attenuation zone according to claim 1, characterized in that: In the above S1, during the stable welding for more than one full cycle, the angle range of the stable welding is controlled to be ~ .

3. The method for eliminating local chain-shaped pore defects in the beam slope attenuation zone according to claim 1, characterized in that: In said S2, during the beam attenuation process of the workpiece to be welded: The angle range corresponding to the beam attenuation process is controlled as follows: ~ ; The linear decay rate of the beam is controlled to be 3mA / s~6mA / s.

4. The method for eliminating local chain-shaped pore defects in the beam slope attenuation zone according to claim 1, characterized in that: In the step S3 , the increasing amount of the focusing current value is controlled to be 30 mA to 60 mA.

5. The method for eliminating local chain-shaped pore defects in the beam slope attenuation zone according to claim 4, characterized in that: In S3, the focusing current value increases at a constant rate, and the increasing process is completed synchronously with the linear attenuation of the beam current.

6. The method for eliminating local chain-shaped pore defects in the beam slope attenuation zone according to claim 1, characterized in that: The material of the workpiece to be welded includes stainless steel material containing nitrogen.

7. The method for eliminating local chain-shaped pore defects in the beam slope attenuation zone according to claim 1, characterized in that: The workpiece to be welded includes an annular workpiece, and the diameter of the weld seam of the annular workpiece is controlled to be 600 mm to 1500 mm.

8. The method for eliminating local chain-shaped air hole defects in the beam slope attenuation zone according to claim 1, characterized in that: In the above S4, when performing local modification welding, the welding area of ​​the local modification welding covers the weld area corresponding to the beam attenuation.

9. A component, characterized in that: The parts are welded by the method for eliminating local chain-shaped porosity defects in the beam slope attenuation zone according to any one of claims 1 to 8.

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