A long-life aluminum alloy resistance welding electrode and a welding method

Abstract

The application discloses a long-life aluminum alloy resistance welding electrode and a welding method, and belongs to the field of welding. The welding electrode comprises an arc-shaped welding end face which is in contact with an aluminum alloy plate to be welded during welding operation, and the welding end face satisfies 9 mu m <= Tu <= 15 mu m, wherein h represents an arbitrary micro-protrusion on the welding end face, along the radial direction of the welding end face, h1 i is the height from the bottom to the top of the micro-protrusion i on the side close to the center, h2 i is the height from the bottom to the top of the micro-protrusion i on the side far from the center, and n >= 5. The diameter of the welding end face satisfies D >= 4 + 5t, and the curvature radius of the welding end face is 60 mm-200 mm, wherein t is the thickness of the thinnest aluminum alloy plate to be welded. The mutual coupling between the geometric characteristics of the welding end face of the welding electrode can significantly improve the service life of the welding electrode.

Description

Technical Field

[0001] This invention belongs to the field of welding, specifically relating to a long-life aluminum alloy resistance welding electrode and welding method. Background Technology

[0002] With the development of lightweighting in automobiles, aluminum alloys are being used more and more in vehicle body structures. Compared with steel, the process of spot welding aluminum alloys is significantly more difficult. The welding current required for spot welding aluminum alloys is nearly three times that of spot welding steel, and the electrode force is nearly twice that of spot welding steel. This leads to a significant increase in the risk of welding defects in aluminum alloy welds.

[0003] Patent CN206356755U provides an electrode cap that improves welding results by creating a raised structure on the electrode welding surface to promote current and heat accumulation. Patent CN104043898A discloses a spherical electrode with multiple annular ridges, which utilizes these ridges to pierce the oxide film on the aluminum alloy surface, thereby improving welding quality. However, in these technical solutions, the current tends to concentrate on the protruding parts of the electrode, leading to premature electrode pitting corrosion, severely affecting electrode lifespan, and hindering cost optimization in the spot welding process.

[0004] Therefore, providing a welding electrode with a longer lifespan for aluminum alloy resistance welding is of positive significance for improving the welding efficiency and cost of aluminum alloys. Summary of the Invention

[0005] The purpose of this invention is to provide a long-life welding electrode for resistance welding of aluminum alloys, thereby improving the service life of the welding electrode. This invention also provides a welding method.

[0006] According to one embodiment of the present invention, a long-life aluminum alloy resistance welding electrode is provided. The long-life aluminum alloy resistance welding electrode includes a welding end face, which is spherical. The welding end face contacts the aluminum alloy plate to be welded during welding operations, and the welding end face has micro-protrusions. The Tu value of the welding end face is defined as:

[0007] ,

[0008] Where h represents any micro-protrusion on the welding end face, and along the radial direction of the welding end face, h1 i h2 is the height from the bottom to the top of the micro-protrusion i near the center. i Let i be the height from the bottom to the top of the micro-protrusion on the side furthest from the center, and n≥5;

[0009] The Tu value of the welded end face satisfies: 9μm≤Tu≤28μm.

[0010] The diameter of the welded end face satisfies D≥4+5 The radius of curvature of the welding end face is 60mm-200mm, where t is the thickness of the thinnest plate among the aluminum alloy plates being welded.

[0011] Furthermore, in some embodiments, the diameter of the welding end face is 10mm-14mm.

[0012] In current resistance welding electrode designs, factors such as the diameter and radius of curvature of the welding end face are controlled as independent parameters to achieve a balance between electrode life and welding quality. However, this invention, through extensive research and experimentation, has discovered a synergistic coupling relationship between the diameter, radius of curvature of the welding end face, and the Tu value. When the diameter, radius of curvature, and Tu value of the welding end face are precisely limited to a certain range, the service life of the welding electrode can be increased by more than two times, effectively improving the economics of aluminum alloy resistance welding.

[0013] Furthermore, in some embodiments, the welding end face includes a textured structure.

[0014] Furthermore, in some embodiments, the convex-concave structure is configured as an undulating annular corrugated structure.

[0015] Furthermore, in some embodiments, the convex-concave structure is configured as a plurality of columnar protrusions and / or recessed blind holes.

[0016] According to another aspect of the present invention, a welding method is provided, which uses the long-life aluminum alloy resistance welding electrode provided in any of the foregoing embodiments to perform aluminum alloy welding.

[0017] Furthermore, in some embodiments, the diameter D of the welded end face satisfies D≥4+5 , where t is the thickness of the thinnest plate in the aluminum alloy sheet being welded; the electrode pressure used during welding is 2kN-6kN.

[0018] Furthermore, in some embodiments, the aluminum alloy plate being welded is configured as a 6-series aluminum alloy.

[0019] Furthermore, in some embodiments, the welding current is 18kA-45kA, and the welding time is 60ms-200ms. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the welding electrode structure in Example 1;

[0021] Figure 2a This is a schematic diagram of the welded end face structure in Example 1;

[0022] Figure 2bThis is a schematic diagram of the welded end face structure in Example 2;

[0023] Figure 2c This is a schematic diagram of the welded end face structure in Example 3;

[0024] Figure 3 This is a schematic diagram of the welding electrode structure in Example 4;

[0025] Figure 4 This is a schematic diagram of the welding electrode structure in Example 5;

[0026] Figure 5 Photographs of weld joint surfaces from comparative examples and embodiments using different Tu values ​​for the welded end faces;

[0027] Figure 6 Photographs of weld joint surfaces in comparative examples and embodiments using different weld end face curvature radii;

[0028] Figure 7 Photographs of the weld joint surfaces of the comparative examples and embodiments using different weld end face diameters;

[0029] Figure 8 These are photographs of the solder joint surfaces in a comparative example.

[0030] Figure 9a This is a diagram showing the surface height distribution of the solder joint before pitting corrosion in Comparative Example 2.

[0031] Figure 9b This is a diagram showing the surface height distribution of the solder joint after pitting corrosion in Comparative Example 2.

[0032] Figure 10 This is a schematic diagram of the welding test device structure in one embodiment;

[0033] Figure 11 This is a schematic diagram of the Tu measurement method in one embodiment;

[0034] Figure 12 This is a schematic diagram of the welding electrode end face structure in one embodiment.

[0035] Meaning of the reference numerals in the attached figures:

[0036] 1-Electrode body; 2-Electrode side; 3-Welding end face; 4-Protruding ring; 5-Concave ring; 6-Boss; 7-Blind hole; 8-Pit corrosion; 9-Upper electrode; 10-Lower electrode; 11-Upper electrode rod; 12-Lower electrode rod; 13-Aluminum plate; 14-Resistance measuring device. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0038] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment herein. The phrase appearing in various places in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive, independent, or alternative embodiments. Those skilled in the art will understand that the embodiments herein can be combined with other embodiments without causing structural conflicts.

[0039] In this article, "multiple" means at least two.

[0040] In the automotive industry, welding is widely used in the body manufacturing process to connect metal components. Among these, resistance spot welding has gained the most widespread application due to its advantages of low cost, short cycle time, high reliability, and good weld quality. Currently, with increasing demands for energy conservation and emission reduction, and growing emphasis on vehicle safety, more and more steel components in the body structure are being replaced by aluminum alloys. Compared to traditional steel, aluminum alloys have only one-third the density, superior specific strength and specific stiffness, and also offer excellent impact energy absorption.

[0041] However, compared to steel, aluminum alloys have better electrical and thermal conductivity, and a dense oxide film naturally forms on their surface. This results in aluminum alloy resistance welding requiring three times the welding current and twice the electrode force compared to steel welding under the same conditions. During resistance spot welding, aluminum alloy welds are more prone to defects such as insufficient weld nugget diameter, spatter, hot cracking, and incomplete fusion, limiting the overall quality of the welded aluminum alloy structure. The rapid degradation and electrode erosion that occur during resistance spot welding between the welding electrode and the aluminum alloy material are closely related to the generation of these welding defects.

[0042] To improve the quality of spot welding of aluminum alloys, some technical solutions incorporate raised structures on the working surface of the welding electrode to concentrate current and heat and penetrate the alumina layer. For example, patent CN206356755U discloses an electrode cap with several raised protrusions on a spherical electrode. The protrusions primarily concentrate current and heat, thereby improving the welding effect of the electrode cap. However, due to the excessive height of the protrusions, the welding current and heat are concentrated on a small number of protrusions, easily leading to excessive heat at the corresponding electrode protrusions and premature electrode pitting, thus affecting welding efficiency. Patent CN104043898A discloses a new electrode with multiple raised annular ridges on a spherical electrode. This method primarily uses the raised rings to pierce the surface oxide film to improve electrode life and surface quality. However, due to the high height and small number of raised rings, the current and heat are mainly concentrated on the raised rings during welding, leading to premature electrode pitting.

[0043] To overcome the shortcomings of existing technologies, embodiments of the present invention provide a long-life welding electrode for resistance welding of aluminum alloys, which has a longer service life when performing resistance spot welding on aluminum alloys. Generally, an electrode with a spot welding life of 50 cycles or more is considered to have a long-life welding effect.

[0044] In Example 1, the structure of the welding electrode is as follows: Figure 1 As shown, the electrode includes an electrode body 1, with an electrode side surface 2 at its end. The electrode side surface 2 is either an arc surface or a conical surface. The electrode body 1 is connected to a welding end face 3 via the electrode side surface 2. During welding, the welding end face 3 is the part of the electrode body 1 that contacts the aluminum alloy material being welded. The Tu value of the welding end face 3 is 9μm-28μm. In a further preferred embodiment, the welding electrode also satisfies the following: the diameter of the welding end face 3 satisfies D≥4+5√t, specifically 10mm-14mm (i.e., the diameter of the circle formed by the outer perimeter of the welding end face 3 is 10mm-14mm), and the radius of curvature of the welding end face 3 is 60mm-200mm. It should be understood that if the radius of curvature is too large, the welding end face 3 will be too close to a plane, which will have an adverse effect on the spot welding of the aluminum alloy; while if the diameter of the welding end face is too large, it will cause the pressure and current to be too dispersed, resulting in a smaller weld nugget diameter, which is not conducive to improving the welding strength.

[0045] The Tu value is calculated as follows: The micro-protrusion structure on the surface of the weld end face is measured along a radial direction. In one example, such as... Figure 12 On the welding electrode end face shown, a radial contour line is as follows: Figure 11 As shown, Figure 11 The left side is the side closest to the center of the welding end face, and the right side is the side furthest from the center of the welding end face. For the micro-protrusion i, h1 i h2 represents the height from the bottom to the top on the side closest to the center. i This represents the height from the bottom to the top on the side furthest from the center. .

[0046] To control the Tu value of the welding end face 3, the welding end face 3 includes a textured structure. In different embodiments, the textured structure can take different forms.

[0047] In Example 1, the cross-sectional profile of the welded end face 3 is as follows: Figure 2a As shown, the concave-convex structure is configured as an undulating annular corrugated structure, including multiple semi-circular convex rings 4 arranged in a concentric circle pattern. The height of the convex rings 4 is h1, the width is d1, and the radial spacing is d0.

[0048] For the welded end face, ,

[0049] h represents any micro-protrusion on the welded end face, along the radial direction of the welded end face, h1 i =h2 i =h1, where n is the total number of semi-circular convex rings 4. In Example 2, the cross-sectional profile of the welding end face 3 is as follows: Figure 2b As shown, the concave-convex structure is configured as an irregular annular corrugated convex ring 4. The maximum height of the irregular annular corrugated convex ring 4 is h1, the average width is d1, and the average interval is d0. The calculation method for its Tu value is the same as in the previous embodiment.

[0050] In Example 3, the cross-sectional profile of the welded end face 3 is as follows: Figure 2c As shown, the concave-convex structure is configured as concentrically arranged concave rings 5, with a maximum depth of h2, a width of d1, and a radial spacing of d0. The calculation method for its Tu value is the same as in the previous embodiment.

[0051] In other embodiments, the corrugated structure may also be configured as a sine wave, a square wave, or other corrugated shapes.

[0052] In Example 4, the structure of the welding electrode is as follows: Figure 3 As shown, the uneven structure on the welding end face 3 is configured as uniformly arranged columnar bosses 6. In embodiment 5, the structure of the welding electrode is as follows: Figure 4 As shown, the uneven structure on the welding end face 3 is configured as uniformly arranged circular blind holes 7. In other embodiments, the uneven structure on the welding end face can also be configured as a hybrid structure of bosses and blind holes, and the bosses and blind holes can also be configured as polygonal, elliptical, or irregular shapes, etc. When the Tu value of the welding end face meets 9μm-28μm, no specific form restriction is imposed on the uneven structure on the welding end face. Welding tests were performed on welding electrodes with different Tu values. The welding electrode with a Tu value of about 15μm had the lowest contact resistance. The reason may be that the uneven structure can penetrate the coating on the surface of the plate to be welded, thereby reducing the contact resistance. When the Tu value is too low, the piercing effect on the coating on the surface of the plate is weak. When the Tu value is too high, the uneven structure is too dense at the microscopic level, resulting in only the raised part contacting the plate, which will also cause the contact resistance to increase. Taking welding electrodes with a radius of curvature of 100 mm and welding end face Tu values ​​of 4 μm, 15 μm, and 32.6 μm as examples, the contact resistance between the welding electrode with a Tu value of 4 μm and the coated aluminum alloy plate was measured to be approximately 29.84 μΩ. The contact resistance of the welding electrode with a Tu value of 15 μm decreased to approximately 20.34 μΩ, while the contact resistance of the welding electrode with a Tu value of 32.6 μm increased to approximately 22.86 μΩ.

[0053] Another embodiment of the present invention provides a welding method for welding aluminum alloys using the welding electrode provided in the above embodiments. In a preferred embodiment, the diameter D of the welding end face 3 satisfies D≥4+5. Where t is the thickness of the thinnest plate in the aluminum alloy sheet being welded; the electrode pressure used during welding is 2kN-6kN. This welding method is particularly suitable for welding 6-series aluminum alloys. In a further preferred embodiment, the welding current is 18kA-45kA, and the welding time is 60ms-200ms.

[0054] The embodiments and comparative examples of the present invention adopt the following methods: Figure 10 The welding test apparatus shown is used to conduct welding tests. The apparatus includes an upper electrode 9 and a lower electrode 10, which are fixedly mounted on upper electrode rod 11 and lower electrode rod 12, respectively. The upper electrode rod 11 and lower electrode rod 12 are coaxially aligned and can move relative to each other to provide welding pressure and welding current to the upper electrode 9 and lower electrode 10. Measuring devices are installed on the upper electrode rod 11 and lower electrode rod 12 to accurately measure the welding pressure. Resistance measuring devices 14 are connected to the upper electrode 9 and lower electrode 10, respectively. The resistance measuring devices 14 can measure the resistance between the upper electrode 9 and lower electrode 10 during the welding process. When the aluminum plate 13 being welded is a single piece, the measured resistance is the contact resistance between the welding electrode and the aluminum plate 13. When the aluminum plate 13 consists of two or more layers of aluminum plates, the measured resistance is the sum of the contact resistance and the welding resistance within the aluminum plate 13.

[0055] Table 1 shows the service life of a set of example and comparative welding electrodes under an electrode pressure of 3.0 kN, a welding current of 45 kA, and a welding time of 80 ms. The welded plates were 0.95 mm thick 6016-T4P aluminum alloy plates. The uneven textured structure in both the example and comparative electrodes adopted a ring-shaped corrugated structure. During the welding process, the surface of the aluminum plate was continuously observed. When obvious pitting corrosion marks appeared on the weld joint surface, the welding electrode was determined to have failed due to pitting corrosion. Calculations showed that for the above-mentioned plates (4+5...),... =8.87mm, and all examples in Table 1 satisfy D≥4+5 However, comparative examples 5, 6, and 8 do not meet the above conditions.

[0056]

[0057] In Table 1, the welding end face diameter and welding end radius of curvature of the welding electrodes in Comparative Examples 1 and 2 are the same as those in Example 6, but the surface Tu values ​​of the welding end faces exceed the range of 9μm-28μm. The surface morphology of the weld points obtained from Comparative Examples 1, 2, 6, 7, and 8 are shown in Table 1. Figure 5 As shown. In Figure 5 In the images, 'a' represents a photograph of the solder joint surface before pitting occurs, and 'b' represents a photograph of the solder joint surface where obvious pitting marks begin to appear. Example 6-a is a photograph of the solder joint surface after 109 welds, at which point no obvious pitting marks have yet appeared; Figure 5 Example 6-b shows a photograph of the weld surface after 112 welding cycles. It can be seen that obvious pitting corrosion marks appeared at the beginning of the test, and the service life of the welding electrode in Example 6 was determined to be 112 cycles under the current welding conditions. Figure 5 In the examples, Example 7-a shows a photograph of the weld joint surface after 140 welding cycles using the welding electrode of Example 7, showing no pitting corrosion; Example 7-b shows a photograph of the weld joint surface after 146 welding cycles, showing the beginning of pitting corrosion. Example 8-a shows a photograph of the weld joint surface after 95 welding cycles using the welding electrode of Example 8, showing no pitting corrosion; Example 8-b shows a photograph of the weld joint surface after 98 welding cycles, showing the beginning of pitting corrosion. As a comparison, Comparative Example 1-a shows a photograph of the weld joint surface after 39 welding cycles using the welding electrode of Comparative Example 1, showing no pitting corrosion; Comparative Example 1-b shows a photograph of the weld joint surface after 41 welding cycles using the welding electrode of Comparative Example 2, showing no pitting corrosion; Comparative Example 2-b shows a photograph of the weld joint surface after 49 welding cycles using the welding electrode of Comparative Example 2, showing the beginning of pitting corrosion. Furthermore, when the welding electrode of Comparative Example 2 is used for 41 welding cycles, the height distribution of the weld joint surface is as follows... Figure 9a As shown, it exhibits a uniform and symmetrical annular distribution; the surface height distribution of the weld points after 49 welding operations is as follows. Figure 9b As shown, obvious adhesion appears in the central area, indicating that the weld points obtained by spot welding the welding electrode of Comparative Example 2 have quality problems.

[0058] As shown in Table 1, Comparative Examples 3 and 4 have the same Tu value and radius of curvature as Examples 9, 10, and 11. However, the welding end face radius of the welding electrodes in Comparative Examples 3 and 4 is less than the lower limit of 60 mm. The surface morphology of the weld points obtained from Comparative Examples 3, 4, 9, 10, and 11 is as follows: Figure 6 As shown. Figure 6In the examples, Example 9-a shows a photograph of the weld joint surface after 185 welding cycles using the welding electrode of Example 9, showing no pitting corrosion; Example 9-b shows a photograph of the weld joint surface after 190 welding cycles, showing the beginning of pitting corrosion; Example 10-a shows a photograph of the weld joint surface after 247 welding cycles using the welding electrode of Example 10, showing no pitting corrosion; Example 10-b shows a photograph of the weld joint surface after 256 welding cycles, showing the beginning of pitting corrosion; Example 11-a shows a photograph of the weld joint surface after 373 welding cycles using the welding electrode of Example 11, showing no pitting corrosion; Example 11-b shows a photograph of the weld joint surface after 379 welding cycles, showing the beginning of pitting corrosion. As a comparison, Comparative Example 3-a shows a photograph of the weld joint surface after 12 welding cycles using the welding electrode of Comparative Example 3, showing no pitting corrosion; Comparative Example 3-b shows a photograph of the weld joint surface after 15 welding cycles, showing the beginning of pitting corrosion. Comparative Example 4-a shows a photograph of the weld joint surface after 24 welding cycles using the welding electrode of Comparative Example 4, showing no pitting corrosion; Comparative Example 4-b shows a photograph of the weld joint surface after 30 welding cycles, showing the beginning of pitting corrosion.

[0059] Comparative Example 5 has the same Tu value and radius of curvature as Examples 12, 13, and 14, but its weld end face diameter is less than the lower limit of 10 mm. The surface morphology of the weld points obtained from Comparative Example 5, Examples 12, 13, and 14 is as follows: Figure 7 As shown. Figure 7 In Example 12-a, a photograph of the weld joint surface after 105 welding cycles using the welding electrode of Example 12 shows no pitting corrosion; Example 12-b, a photograph of the weld joint surface after 108 welding cycles shows the beginning of pitting corrosion. Example 13-a, a photograph of the weld joint surface after 117 welding cycles using the welding electrode of Example 13 shows no pitting corrosion; Example 13-b, a photograph of the weld joint surface after 120 welding cycles shows the beginning of pitting corrosion. Example 14-a, a photograph of the weld joint surface after 130 welding cycles using the welding electrode of Example 14 shows no pitting corrosion; Example 14-b, a photograph of the weld joint surface after 136 welding cycles shows the beginning of pitting corrosion. For comparison, Figure 7 In the comparison, Comparative Example 5-a is a photograph of the weld surface after 35 welding cycles of the welding electrode of Comparative Example 5, showing no pitting corrosion; Comparative Example 5-b is a photograph of the weld surface after 36 welding cycles, showing the beginning of pitting corrosion.

[0060] Comparative Examples 6, 7, and 8 were used to compare and verify the synergistic effect among the three parameters: the diameter of the welding electrode end face, the Tu value of the welding end face, and the radius of curvature of the welding end face. The surface morphology of the weld points obtained from their welding is as follows: Figure 8 As shown. In Figure 8In the comparison, Comparative Example 6-a shows a photograph of the weld joint surface after 10 welding cycles using the welding electrode of Comparative Example 6, showing no pitting corrosion; Comparative Example 6-b shows a photograph of the weld joint surface after 13 welding cycles, showing the beginning of pitting corrosion. Comparative Example 7-a shows a photograph of the weld joint surface after 19 welding cycles using the welding electrode of Comparative Example 7, showing no pitting corrosion; Comparative Example 7-b shows a photograph of the weld joint surface after 22 welding cycles, showing the beginning of pitting corrosion; Comparative Example 8-a shows a photograph of the weld joint surface after 27 welding cycles using the welding electrode of Comparative Example 8, showing no pitting corrosion; Comparative Example 8-b shows a photograph of the weld joint surface after 31 welding cycles, showing the beginning of pitting corrosion.

[0061] By comparing the above embodiments and comparative examples, it can be seen that the welding electrode provided by the embodiments of the present invention, through strict control of the welding end face diameter, welding end face Tu value, and welding end face radius of curvature, achieves synergy among different bonding characteristics of the welding electrode, effectively improving the service life of the welding electrode. Experimental data from various comparative examples show that if any parameter exceeds the range required by the embodiments of the present invention, it will cause a significant deterioration in the service life of the welding electrode. The service life of the welding electrodes in the comparative examples is generally less than 50% of that in the embodiments of the present invention; in comparative examples 7, 8, and 9, which only meet the requirements of one parameter, the service life of the welding electrodes in the comparative examples can only reach about 10% of that in the preferred embodiment. Therefore, the welding electrode provided by the embodiments of the present invention achieves unexpected technical effects and effectively extends the service life of the welding electrode.

[0062] The purpose of the above embodiments is to provide a detailed description of the present invention in conjunction with the accompanying drawings, so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present invention, optimizations or equivalent substitutions of the technical features involved, as well as combinations of implementation methods in different embodiments without causing a conflict of principles, all fall within the protection scope of the present invention.

Claims

1. A long-life welding electrode for resistance welding of aluminum alloys, characterized in that, The long-life aluminum alloy resistance welding electrode includes a welding end face, which is spherical. During welding operations, the welding end face contacts the aluminum alloy plate being welded. Furthermore, the welding end face includes a textured structure, which is a micro-protrusion. The Tu value of the welding end face is defined as follows: ， Where h represents any micro-protrusion on the welding end face, and along the radial direction of the welding end face, h1 i h2 is the height from the bottom to the top of the micro-protrusion i near the center. i Let i be the height from the bottom to the top of the micro-protrusion on the side furthest from the center, and n≥5; The Tu value of the welded end face satisfies: 9μm≤Tu≤15μm; The diameter of the welded end face satisfies D≥4+5 , where t is the thickness of the thinnest aluminum alloy plate being welded; The radius of curvature of the welded end face is 60mm-200mm; The diameter of the welded end face is 10mm-14mm.

2. The long-life aluminum alloy resistance welding electrode according to claim 1, characterized in that, The convex-concave structure is configured as an undulating annular corrugated structure.

3. The long-life aluminum alloy resistance welding electrode according to claim 2, characterized in that, The convex-concave structure is configured as a plurality of columnar protrusions and / or recessed blind holes.

4. A welding method, characterized in that, Aluminum alloy welding is performed using the long-life aluminum alloy resistance welding electrode as described in any one of claims 1 to 3.

5. The welding method according to claim 4, characterized in that, The diameter D of the welded end face satisfies D≥4+5 , where t is the thickness of the thinnest plate in the aluminum alloy sheet being welded; the electrode pressure used during welding is 2kN-8kN.

6. The welding method according to claim 5, characterized in that, The welding current is 18kA-45kA, and the welding time is 60ms-200ms.

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