Vacuum electron beam double-sided inclined angle welding process of t-joint metal

Abstract

The application discloses a vacuum electron beam double-sided inclined-angle welding process for T-shaped joint metal and relates to the technical field of vacuum electron beam welding.The technical scheme of the application realizes full contact of double-sided molten pools and 100% coverage of the joint surface by precisely controlling the electron beam angle and the offset, effectively eliminates defects such as incomplete fusion and incomplete penetration, and ensures the fusion integrity of the joint.Further, the double-sided welding process can effectively inhibit grain coarsening and deformation, the weld structure is dense and uniform, there are no pores, cracks and slag, and the ultrasonic detection is stable and reaches the I-class standard.The parameter window is wide, the batch consistency is good, and the process is suitable for large-scale production;step-by-step cooling and heat control significantly reduce residual stress and deformation and improve the dimensional accuracy;and the process is highly versatile and suitable for the welding of inclined-angle structures of thick plates made of titanium alloy, stainless steel and other metals.

Description

Technical Field

[0001] This invention relates to the field of vacuum electron beam welding technology, and in particular to a vacuum electron beam double-sided bevel welding process for T-joint metals. Background Technology

[0002] As a common connection method in mechanical structures, the welding quality of T-joints directly affects the load-bearing capacity, sealing performance, and service safety of the overall structure.

[0003] With the increasing size of equipment and more stringent service conditions, the demand for T-welding of thick metal plates (10-80mm) such as titanium alloys and stainless steel is growing. However, traditional welding methods are prone to welding defects when dealing with this thickness range, especially leaving tiny unfused gaps at the root of the bevel, making it difficult to meet the Class I requirements for ultrasonic testing. In addition, traditional electron beam welding has low strength when penetrating the panel to connect with the web, and the process window is very narrow; when dealing with thick plates, even higher power welding parameters are required, which makes it more prone to defects.

[0004] Therefore, there is an urgent need to develop a high-quality welding process for T-joints suitable for metal plates with a thickness of 10-80mm, so as to achieve 100% fusion of the beveled surfaces and meet the requirements of ultrasonic testing for Class I welds. Summary of the Invention

[0005] The main objective of this invention is to propose a vacuum electron beam double-sided bevel welding process for T-joint metals, aiming to achieve 100% fusion of the beveled surfaces and meet the requirements of ultrasonic testing for Class I welds.

[0006] To achieve the above objectives, this invention proposes a vacuum electron beam double-sided bevel welding process for T-joint metals, comprising the following steps: Pre-welding preparation: T-joint the panel and web to obtain the workpiece to be welded; The thickness of the panel and the thickness of the web are both 10-80 mm. First side welding: Place the workpiece to be welded in the vacuum chamber, start the electron gun to weld one side of the fillet weld along the weld direction, and cool to room temperature after welding is completed; Second side welding: Start the electron gun to weld the other side of the fillet weld along the weld direction. After welding is completed, cool to room temperature and remove from the vacuum chamber; In the first and second side welding, the angle between the electron beam and the panel is 6 to 15°; the distance between the spot where the electron beam acts on the web and the panel is 0.6 to 1.5 mm.

[0007] Preferably, in the welding of the first side and the welding of the second side, the accelerating voltage for welding is 60-80kV.

[0008] Preferably, in the welding of the first side and the welding of the second side, the electron beam current is 50 to 200 mA.

[0009] Preferably, in the welding of the first side and the welding of the second side, the focusing current of the welding is JO~(JO+60)mA.

[0010] Preferably, the welding speed in the first and second side welding is 150-500 mm / min.

[0011] Preferably, during the welding of the first and second surfaces, the vacuum level of the vacuum chamber is ≤5×10⁻⁶. -2 Pa, the vacuum degree of the electron gun is ≤5×10 -3 Pa.

[0012] Preferably, the welding parameters for the first side welding are the same as those for the second side welding.

[0013] Preferably, the pre-welding preparation further includes: after T-jointing the panel and the web, fixing them by spot welding to obtain the workpiece to be welded.

[0014] Preferably, the pre-welding preparation further includes: Before T-shaped docking, the panel and web were sequentially washed with alkali, water, and ethanol under ultrasonic assistance and then dried.

[0015] Preferably, the pre-welding preparation further includes: After performing the T-joint, wipe the fillet weld with ethanol or acetone.

[0016] The technical solution of this invention achieves full contact of the double-sided molten pool and 100% coverage of the joint surface by precisely controlling the electron beam angle and offset, effectively eliminating defects such as incomplete fusion and incomplete penetration, and ensuring the integrity of the joint fusion. Furthermore, the double-sided welding process of this solution effectively suppresses grain coarsening and deformation, resulting in a dense and uniform weld structure free of porosity, cracks, and slag inclusions, with ultrasonic testing consistently meeting Level I standards. It features a wide parameter window, good batch-to-batch consistency, and suitability for large-scale production; step-by-step cooling and thermal control significantly reduce residual stress and deformation, improving dimensional accuracy; and it is highly versatile, suitable for welding thick plates with beveled structures made of various metals such as titanium alloys and stainless steel. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 A schematic diagram of electron beam control for a vacuum electron beam double-sided bevel welding process of T-joint metal provided by the present invention; Figure 2 This is a cross-sectional view of the weld seam of the welded component in Embodiment 1 of the present invention; Figure 3 This is a surface view of the weld formed by the first welding in Embodiment 1 of the present invention; Figure 4 This is a surface view of the weld formed by welding the second side in Embodiment 1 of the present invention; Figure 5 This is a cross-sectional view of the weld seam of the welded component in Embodiment 2 of the present invention; Figure 6 This is a surface view of the weld formed by the first welding in Embodiment 2 of the present invention; Figure 7 This is a surface view of the weld formed by welding the second side in Embodiment 2 of the present invention; The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0021] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0022] For welding T-joints in metals with a thickness of 10–80 mm, existing connection technologies still face numerous technical bottlenecks in actual production, making it difficult to simultaneously ensure weld quality and joint performance. Specifically: In existing technologies, conventional electron beam welding is commonly used for thick plate T-joints. However, this conventional process is prone to internal defects such as incomplete penetration and discontinuous fusion during deep penetration welding, severely weakening the joint's load-bearing capacity. Especially in welding scenarios involving angled structures, the directional nature of the welding heat source and the flow behavior of the molten pool make it difficult for the molten pool to accurately cover the designed joint surface. This easily leads to localized incomplete fusion defects at the root, resulting in micro-defects remaining inside the weld. The weld quality fails to meet the high standards of ultrasonic testing (Level I), posing a threat to the safe service of the structural components. Furthermore, traditional electron beam welding has low strength when penetrating the panel and then connecting to the web, and the process window is very narrow. When dealing with thick plates, even higher power welding parameters are required, further increasing the likelihood of defects.

[0023] Therefore, in order to achieve 100% fusion of the beveled surfaces and meet the requirements of ultrasonic Class I weld inspection, this technical solution proposes a vacuum electron beam double-sided bevel welding process for T-joint metals, including the following steps: Pre-welding preparation: T-joint the panel and web to obtain the workpiece to be welded; The thickness of the panel and the thickness of the web are both 10-80 mm. First side welding: Place the workpiece to be welded in the vacuum chamber, start the electron gun to weld one side of the fillet weld along the weld direction, and cool to room temperature after welding is completed; Second side welding: Start the electron gun to weld the other side of the fillet weld along the weld direction. After welding is completed, cool to room temperature and remove from the vacuum chamber; In the first and second side welding, the angle between the electron beam and the panel is 6 to 15°; the distance between the spot where the electron beam acts on the web and the panel is 0.6 to 1.5 mm.

[0024] The welding process proposed in this scheme involves adjusting the angle of the electron beam during double-sided welding (e.g., ...). Figure 1 ∠a (as shown, the angle between the electron beam and the panel) and offset (as shown) Figure 1 The distance 'd' (the distance between the spot and the plate when the electron beam acts on the web) is controlled to achieve mutual contact between the two molten pools and 100% coverage of the T-joint's mating surface. This effectively eliminates existing welding defects such as incomplete fusion and incomplete penetration, ensuring the integrity of the joint fusion. Simultaneously, it helps to mitigate the effects of heat input superposition caused by double-sided welding, which leads to coarse grains, large deformation, and decreased mechanical properties. The weld exhibits a dense and uniform internal structure, free from defects such as porosity, cracks, and slag inclusions. Ultrasonic non-destructive testing verifies that its quality consistently meets the Class I standard.

[0025] Furthermore, the double-sided welding process of this solution has a wide parameter adjustment window, maintaining good welding consistency across different batches and operating conditions, providing a reliable guarantee for large-scale mass production. Simultaneously, during the double-sided welding process, step-by-step cooling and heat input control effectively suppresses the accumulation of thermal stress and residual deformation, significantly improving the dimensional accuracy of the parts. Moreover, the double-sided welding process of this solution has strong versatility, applicable not only to the welding of thick plate beveled structures of reactive metals such as titanium alloys, but also stably applied to various metal materials such as stainless steel.

[0026] To further explain, the accelerating voltage for welding the first and second sides is 60-80kV.

[0027] The preferred accelerating voltage for welding in this scheme is 60-80kV, which is beneficial for providing a higher electron penetration speed to match the deep penetration welding of thick plates.

[0028] To further explain, in the welding of the first side and the welding of the second side, the electron beam current is 50-200mA.

[0029] Since this welding process is a double-sided input process, excessive heat input on both sides can easily lead to defects such as coarse grains, large deformation, and decreased mechanical properties. Therefore, while ensuring the integrity of the joint fusion, this solution also optimizes the electron beam current for welding based on the accelerating voltage. This is to avoid excessive power, which may lead to an overly narrow weld, unstable molten pool, or even cutting through the base material, while also preventing insufficient power, which may result in insufficient penetration or incomplete weld penetration.

[0030] To further explain, in the welding of the first side and the welding of the second side, the focusing current of the welding is JO~(JO+60)mA.

[0031] The focusing current determines the focal size and energy density of the electron beam. The focusing current provided by this scheme can form a stable keyhole effect, ensuring the ratio of melt depth to melt width, so as to prevent energy dispersion, insufficient melt depth or uncontrolled melt pool shape caused by poor focusing.

[0032] To further clarify, the welding speed in the first and second side welding is 150–500 mm / min.

[0033] Welding speed affects heat input to some extent; therefore, this solution also optimizes the welding speed. If the speed is too fast, the heat input may be insufficient, resulting in shallow penetration and poor fusion. If the speed is too slow, the heat input may be too large, leading to excessively wide welds and coarse grains.

[0034] To further clarify, during the welding of the first and second sides, the vacuum level of the vacuum chamber is ≤5×10⁻⁶. -2 Pa, the vacuum degree of the electron gun is ≤5×10 -3 Pa.

[0035] To further clarify, the welding parameters for the first side and the second side are the same. By controlling the same welding parameters for both sides, it is beneficial to achieve symmetrical heat input, minimize welding deformation, and ensure uniform microstructure and properties of the heat-affected zones on both sides, thus avoiding overheating on one side.

[0036] To further explain, the pre-welding preparation also includes: after T-jointing the panel and web, fixing them by spot welding to obtain the workpiece to be welded.

[0037] Spot welding can temporarily position the butt joint between the panel and the web, ensuring the assembly accuracy of the T-joint and the stability of the root gap. It helps to prevent misalignment or deformation caused by thermal stress during welding, provides a precise reference for double-sided electron beam welding, and ensures the quality of weld formation and structural integrity.

[0038] To further explain, the pre-welding preparation also includes: Before T-joint welding, the faceplate and web are sequentially cleaned with alkali, water, and ethanol under ultrasonic assistance, and then dried. This process helps remove oil, oxide film, and moisture from the base material surface, and the ultrasonic cavitation effect enhances the cleanliness of complex areas such as the root of the T-joint, preventing porosity and incomplete fusion defects during welding and ensuring the surface activity of the base material.

[0039] To further explain, the pre-welding preparation also includes: After performing the T-joint, wipe the fillet weld with ethanol or acetone.

[0040] For large components that are difficult to clean with ultrasonic cleaning, ethanol or acetone can be used to wipe and clean the welding area. Ethanol or acetone can quickly evaporate and remove oil, oxide film and moisture from the surface of the fillet weld, avoiding porosity and lack of fusion defects during welding and ensuring the cleanliness of the fillet weld area.

[0041] The present invention will be further illustrated below through specific embodiments: Example 1 (1) Pre-welding preparation: T-shaped butt joint of 14mm TC4 titanium alloy panel and 14mm TC4 titanium alloy web, and fix by spot welding to obtain the workpiece to be welded.

[0042] (2) First-side welding: Place the workpiece to be welded in the vacuum chamber and evacuate the vacuum chamber to a vacuum level of 4.0 × 10⁻⁶. - 2 Pa, then the vacuum level of the electron gun was evacuated to 1.1 × 10⁻⁶. -3 Pa, start the electron gun to weld the fillet weld on one side along the weld direction, and cool to room temperature after welding is completed; The angle between the electron beam and the panel is 12°, the distance between the spot on the web and the panel is 1.5 mm, the accelerating voltage is 65 kV, the electron beam current is 80 mA, the focusing current is JO+25 mA, and the welding speed is 450 mm / min.

[0043] (3) Second side welding: Start the electron gun to weld the other side of the fillet weld along the weld direction. After welding, cool to room temperature and remove from the vacuum chamber; The angle between the electron beam and the panel is 12°, the distance between the spot on the web and the panel is 1.5 mm, the accelerating voltage is 65 kV, the electron beam current is 80 mA, the focusing current is JO+25 mA, and the welding speed is 450 mm / min.

[0044] The weld cross-sectional view of the welded part obtained in Example 1 is shown below. Figure 2 As shown, the two-sided molten pools are completely bonded, specifically: The surface diagram of the weld formed by the first welding is shown below. Figure 3 As shown, the surface is uniformly formed and free of cracks. Metallographic analysis shows that the weld penetration is 14.494 mm, the surface weld width is 4.641 mm, and the weld width at 1 / 3 of the weld is 2.403 mm. Ultrasonic testing (UT) inside the weld showed no defects exceeding the standard, including no cracks, no incomplete penetration, no lack of fusion, no dense porosity, no strip-shaped slag inclusions, etc., which meet the requirements of Class I weld.

[0045] The surface diagram of the weld formed by the second welding is shown below. Figure 4 As shown, the surface is uniformly formed and free of cracks. Metallographic analysis shows that the weld penetration is 14.216 mm, the surface weld width is 4.554 mm, and the weld width at 1 / 3 of the weld is 2.492 mm. Ultrasonic testing (UT) inside the weld showed no defects exceeding the standard, including no cracks, no incomplete penetration, no lack of fusion, no dense porosity, no strip-shaped slag inclusions, etc., which meet the requirements of Class I weld.

[0046] Example 2 (1) Pre-welding preparation: T-shaped butt joint of 35mm 304 stainless steel panel and 35mm 304 stainless steel web, and fix by spot welding to obtain the workpiece to be welded.

[0047] (2) First-side welding: Place the workpiece to be welded in the vacuum chamber and evacuate the vacuum chamber to a vacuum level of 3.0 × 10⁻⁶. - 2 Pa, then the vacuum level of the electron gun was evacuated to 1.5 × 10⁻⁶. -3 Pa, start the electron gun to weld the fillet weld on one side along the weld direction, and cool to room temperature after welding is completed; The angle between the electron beam and the panel is 8°, the distance between the spot on the web and the panel is 1.5 mm, the accelerating voltage is 65 kV, the electron beam current is 110 mA, the focusing current is JO+45 mA, and the welding speed is 200 mm / min.

[0048] (3) Second side welding: Start the electron gun to weld the other side of the fillet weld along the weld direction. After welding, cool to room temperature and remove from the vacuum chamber; The angle between the electron beam and the panel is 8°, the distance between the spot on the web and the panel is 1.5 mm, the accelerating voltage is 65 kV, the electron beam current is 110 mA, the focusing current is JO+45 mA, and the welding speed is 200 mm / min.

[0049] The weld cross-sectional view of the welded part obtained in Example 2 is shown below. Figure 5 As shown, the two-sided molten pools are completely bonded, specifically: The surface diagram of the weld formed by the first welding is shown below. Figure 6 As shown, the surface is uniformly formed and free of cracks. Metallographic analysis shows that the weld penetration is 27.141 mm, the surface weld width is 8.291 mm, and the weld width at 1 / 3 of the weld is 3.281 mm. Ultrasonic testing (UT) inside the weld showed no defects exceeding the standard, including no cracks, no incomplete penetration, no lack of fusion, no dense porosity, no strip-shaped slag inclusions, etc., which meet the requirements of Class I weld.

[0050] The surface diagram of the weld formed by the second welding is shown below. Figure 7 As shown, the surface is uniformly formed and free of cracks. Metallographic analysis shows that the weld penetration is 26.418 mm, the surface weld width is 7.163 mm, and the weld width at 1 / 3 of the weld is 3.493 mm. Ultrasonic testing (UT) inside the weld showed no defects exceeding the standard, including no cracks, no incomplete penetration, no lack of fusion, no dense porosity, no strip-shaped slag inclusions, etc., which meet the requirements of Class I weld.

[0051] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A vacuum electron beam double-sided bevel welding process for T-joint metals, characterized in that, Includes the following steps: Pre-welding preparation: T-joint the panel and web to obtain the workpiece to be welded; The thickness of the panel and the thickness of the web are both 10-80 mm. First side welding: Place the workpiece to be welded in the vacuum chamber, start the electron gun to weld one side of the fillet weld along the weld direction, and cool to room temperature after welding is completed; Second side welding: Start the electron gun to weld the other side of the fillet weld along the weld direction. After welding is completed, cool to room temperature and remove from the vacuum chamber; In the first and second side welding, the angle between the electron beam and the panel is 6 to 15°; the distance between the spot where the electron beam acts on the web and the panel is 0.6 to 1.5 mm.

2. The vacuum electron beam double-sided bevel welding process for T-joint metals as described in claim 1, characterized in that, In both the first and second side welding processes, the accelerating voltage for welding is 60–80 kV.

3. The vacuum electron beam double-sided bevel welding process for T-joint metal as described in claim 2, characterized in that, In the welding of the first and second sides, the electron beam current is 50-200mA.

4. The vacuum electron beam double-sided bevel welding process for T-joint metal as described in claim 1, characterized in that, In the welding of the first side and the welding of the second side, the focusing current of the welding is JO~(JO+60)mA.

5. The vacuum electron beam double-sided bevel welding process for T-joint metals as described in claim 1, characterized in that, In the welding of the first and second sides, the welding speed is 150-500 mm / min.

6. The vacuum electron beam double-sided bevel welding process for T-joint metals as described in claim 1, characterized in that, During the welding of the first and second sides, the vacuum degree of the vacuum chamber is ≤5×10⁻⁶. -2 Pa, the vacuum degree of the electron gun is ≤5×10 -3 Pa.

7. The vacuum electron beam double-sided bevel welding process for T-joint metals as described in claim 1, characterized in that, The welding parameters for the first side and the welding parameters for the second side are the same.

8. The vacuum electron beam double-sided bevel welding process for T-joint metals as described in claim 1, characterized in that, The pre-welding preparation also includes: after T-jointing the panel and web, fixing them by spot welding to obtain the workpiece to be welded.

9. The vacuum electron beam double-sided bevel welding process for T-joint metals as described in claim 1, characterized in that, The pre-welding preparation also includes: Before T-shaped docking, the panel and web were sequentially washed with alkali, water, and ethanol under ultrasonic assistance and then dried.

10. The vacuum electron beam double-sided bevel welding process for T-joint metals as described in claim 1, characterized in that, The pre-welding preparation also includes: After performing the T-joint, wipe the fillet weld with ethanol or acetone.

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