A method for welding Hastelloy foil based on resistance welding

Abstract

This invention discloses a method for welding Hastelloy foil using resistance welding, relating to the field of welding technology. The method includes the following steps: Step 1, pre-treating the offshore wind turbine assembly and the Hastelloy foil; Step 2, adjusting the shape of the resistance welding head using sandpaper; Step 3, clamping the grounding cable of the resistance welding equipment onto the offshore wind turbine assembly and placing the Hastelloy foil at the welding position on the assembly; Step 4, adjusting the resistance welding current to complete the spot welding. This method ensures the integrity and corrosion resistance of the Hastelloy foil, which serves as a corrosion-resistant protective layer for the offshore wind turbine assembly, in contact with the marine corrosive environment, as well as a tight welded bond between the Hastelloy foil and the offshore wind turbine assembly.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and in particular to a method for welding Hastelloy foil based on resistance welding. Background Technology

[0002] Wind power is the world's fastest-growing green energy technology. While onshore wind farms are rapidly developing, the abundant offshore wind energy resources and the feasibility of current technology make the ocean a rapidly growing wind power market. However, because offshore wind turbine components are exposed to the marine atmosphere for extended periods, their coatings are less dense and cannot withstand the penetration of corrosive media such as water vapor and chloride ions into the substrate. This leads to localized corrosion of the turbines and even metal breakage, resulting in economic losses.

[0003] Hastelloy is one of the most corrosion-resistant modern metallic materials, exhibiting excellent resistance to most corrosive media, including pitting corrosion, crevice corrosion, and stress corrosion. Furthermore, Hastelloy is one of the few materials resistant to corrosion from moist chlorine gas, hypochlorites, and chlorine dioxide solutions, and also shows good resistance to high-concentration chloride solutions, such as ferric chloride and copper chloride. Therefore, Hastelloy is well-suited for applications in harsh corrosive environments, such as in petrochemical, papermaking, flue gas desulfurization, and environmental protection industries. However, research on the welding performance of Hastelloy has primarily focused on Hastelloy plates. For thin Hastelloy foils, welding methods such as argon arc welding and laser welding can directly melt through the foil. The flow of the molten pool allows corrosive elements to surge to the surface of the Hastelloy foil, significantly reducing the corrosion resistance at the weld joint and resulting in low shear tensile strength. Therefore, using Hastelloy foil as a corrosion protection layer for other metallic materials is not a viable solution. Summary of the Invention

[0004] The purpose of this invention is to provide a method for welding Hastelloy foil based on resistance welding, which ensures the integrity and corrosion resistance of the Hastelloy foil, which serves as a corrosion-resistant protective layer for offshore wind power generation components, in contact with the marine corrosive environment, as well as the tight welding bond between the Hastelloy foil and the offshore wind power generation components.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] This invention provides a method for welding Hastelloy foil based on resistance welding, comprising the following steps:

[0007] Step 1: Pre-treat the structure to be welded and the Hastelloy foil;

[0008] Step 2: Use sandpaper to adjust the shape of the resistance welding head;

[0009] Step 3: Clamp the grounding cable of the resistance welding equipment onto the structure to be welded, and place the Hastelloy foil at the welding position of the structure to be welded.

[0010] Step 4: Adjust the resistance welding current to complete the spot welding.

[0011] Preferably, in step one, the Hastelloy foil is a Hastelloy C-276 foil with a thickness between 0.06mm and 0.15mm, and the thickness of the structure to be welded is greater than 1mm.

[0012] Preferably, in step one, when pre-treating the structure to be welded and the Hastelloy foil, the structure to be welded is polished with 400-grit sandpaper, and the Hastelloy foil is polished with 2000-grit sandpaper. The polished structure to be welded and the Hastelloy foil are then cleaned with ethanol.

[0013] Preferably, in step two, when adjusting the shape of the resistance welding head with sandpaper, the edges of the resistance welding head are polished smooth with 400-grit sandpaper to remove the ridges, the welding contact surface of the resistance welding head is polished smooth and flat with 2000-grit sandpaper, and the polished resistance welding head is cleaned with ethanol.

[0014] Preferably, in step three, the Hastelloy foil is laid flat on the structure to be welded, a round resistance welding head or a flat resistance welding head is selected, and the resistance welding head is pressed vertically onto the Hastelloy foil.

[0015] Preferably, in step four, the welding current used when selecting a round resistance welding head is 70A-90A, and the welding current used when selecting a flat resistance welding head is 30A-40A.

[0016] Preferably, in step four, during the welding process, the molten pool is located between the Hastelloy foil and the structure to be welded, and the melting thickness of the Hastelloy foil does not exceed two-thirds of the thickness of the Hastelloy foil.

[0017] Preferably, in step four, when using a flat resistance welding head for continuous spot welding, the interval between weld spots is 0.5mm. Welding starts from the first weld spot with a welding current of 30A, and the welding current of each subsequent weld spot is increased by 30%-35% compared to the first weld spot.

[0018] Preferably, in step four, when using a round resistance welding head, the welding current is 70A-90A; when using a flat resistance welding head, the welding current is 30A-40A.

[0019] The present invention achieves the following technical effects compared to the prior art:

[0020] The method of resistance welding of Hastelloy foil according to this invention enables spot welding of Hastelloy foil to the structure to be welded (offshore wind turbine components). The weld joint is located on the contact surface between the Hastelloy foil and the offshore wind turbine component. When Hastelloy foil is used as an anti-corrosion layer, the weld joint is located on the opposite side of the corroded surface of the Hastelloy foil, and the weld joint does not directly contact the corrosive environment, thus avoiding corrosion failure of the weld joint. This welding method will not weld through the 0.08mm thick Hastelloy foil, avoiding the problem of corrosion resistance failure at the weld-through point due to welding at the contact surface between the Hastelloy foil and the marine corrosive environment. The shear tensile tear force of a single weld point of Hastelloy foil is above 90N. When using this method to weld Hastelloy foil to offshore wind turbine components, the weld joint has a good weld bond. In the continuous spot welding process using a flat resistance welding head, a continuous weld can be obtained, achieving the sealing welding of the anti-corrosion layer. Attached Figure Description

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1a This is a topographic image of a circular resistance welding head;

[0023] Figure 1b A topographical diagram of a flat resistance welding head;

[0024] Figure 2 A schematic diagram of resistance spot welding method for Hastelloy foil and offshore wind power generation components;

[0025] Figure 3a Image of the surface morphology of the Hastelloy foil weld joint after resistance spot welding;

[0026] Figure 3b Image showing the surface morphology of the weld joints on the Hastelloy foil after laser welding;

[0027] Figure 4a The image shows the cross-section of a resistance spot weld under an optical microscope.

[0028] Figure 4b The image shows the cross-sectional morphology of a resistance spot weld under a scanning electron microscope.

[0029] Figure 5a A schematic diagram of a tensile shear test on Hastelloy foil after welding.

[0030] Figure 5bThe image shows the morphology of the weld joints on the Hastelloy foil after a tensile shear test.

[0031] Figure 5c Tensile curve of the weld joint of Hastelloy foil;

[0032] Figure 6 This is a morphological image of a continuous weld after welding with a flat resistance welding head.

[0033] Among them: 1-Hastelloy foil, 2-Offshore wind power generation components, 3-Resistance welding head. Detailed Implementation

[0034] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] The purpose of this invention is to provide a method for welding Hastelloy foil based on resistance welding, which ensures the integrity and corrosion resistance of the Hastelloy foil, which serves as a corrosion-resistant protective layer for offshore wind power generation components, in contact with the marine corrosive environment, as well as the tight welding bond between the Hastelloy foil and the offshore wind power generation components.

[0036] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] As shown in Figure 1 to Figure 3a , Figures 4a to 6 As shown: This embodiment provides a method for welding Hastelloy foil based on resistance welding. The structure to be welded is an offshore wind power generation component, and includes the following steps:

[0038] Step 1: Hastelloy foil 1 is Hastelloy C-276 foil with a thickness between 0.06mm and 0.15mm. Offshore wind turbine component 2 is a 3mm thick 316L stainless steel plate. Pre-treatment is performed on offshore wind turbine component 2 and Hastelloy foil 1. 400-grit sandpaper is used to polish offshore wind turbine component 2 to ensure that the surface is free of protrusions or depressions. The metal powder on the surface is cleaned with ethanol. 2000-grit sandpaper is used to lightly polish Hastelloy foil 1 to remove the outer skin, only increasing the surface roughness. It is then cleaned with ethanol.

[0039] Step two: Adjust the shape of the resistance welding head 3 with sandpaper. Smooth the edges of the resistance welding head 3 with 400-grit sandpaper to remove any sharp lines. Smooth the welding contact surface of the resistance welding head 3 with 2000-grit sandpaper to ensure a smooth and even contact surface with the Hastelloy foil 1 being welded. Clean the polished resistance welding head 3 with ethanol. (The circular resistance welding head is shown in the image.) Figure 1a As shown, the flat resistance welding head is as follows Figure 1b As shown;

[0040] Step 3: Clamp the grounding cable of the resistance welding equipment onto the offshore wind turbine component 2, ensuring good contact and unobstructed circuitry. Lay the Hastelloy foil 1 flat on the welding position of the offshore wind turbine component 2, ensuring there are no foreign objects in the middle. Select a round or flat resistance welding head according to the required weld morphology, and press the resistance welding head 3 vertically onto the Hastelloy foil 1, ensuring uniform pressure on the pressing surface. Ensure full contact between the welding position of the Hastelloy foil 1 and the welding position of the offshore wind turbine component 2, with a pressure of approximately 10N. A welding diagram is shown below. Figure 2 As shown;

[0041] Step 4: When selecting a round resistance welding head, the welding current used is 70A-90A; when selecting a flat resistance welding head, the welding current used is 30A-40A. Adjust the welding time to complete the spot welding. During the welding process, the molten pool is located between the Hastelloy foil 1 and the offshore wind power generation component 2. The melting thickness of the Hastelloy foil 1 does not exceed two-thirds of the thickness of the Hastelloy foil 1, and is only between 40μm and 50μm.

[0042] In this embodiment, a circular resistance welding head is selected for welding, resulting in several dispersed circular weld points with a diameter of 0.35 mm. The surface of the Hastelloy foil 1 remains intact. When using the circular resistance welding head, the welding current is 70A-90A, preferably 80A. During the welding process, the Hastelloy foil 1 maintains good contact with the resistance welding head 3, while the contact resistance between the Hastelloy foil 1 and the offshore wind turbine component 2 is relatively high. The weld pool is located at the contact point between the Hastelloy foil and the offshore wind turbine component 2. After cutting, polishing, and etching with a specific etchant, the weld morphology is finally obtained as shown below. Figure 4a As shown.

[0043] Through the Figure 4a and Figure 4b Weld morphology analysis of the Hastelloy foil 1 weld joint shows that the weld joint diameter is approximately 0.35 mm, and about 0.05 mm of the 0.08 mm thick Hastelloy foil 1 has melted, forming an effective metallurgical bond with the offshore wind power generation component 2. According to... Figure 3a Surface morphology of Hastelloy foil 1 after welding and Figure 4aAs can be seen from the cross-sectional morphology of the weld, this welding method can effectively spot weld the Hastelloy foil 1 to the offshore wind power generation component 2 without damaging the surface integrity of the Hastelloy foil 1. In practical applications, it can serve as an effective corrosion-resistant layer to prevent the corrosive environment from eroding the offshore wind power generation component 2.

[0044] use Figure 5a Tensile shear tests were conducted on the welded parts obtained by circular resistance welding heads using the method described in the article. The failure cause of the welded part between Hastelloy foil 1 and offshore wind power generation component 2 was tearing of Hastelloy foil 1 around the spot weld joint. The surface morphology of the weld joint after tearing is as follows: Figure 5b As shown. In Figure 5c The tensile shear test curves show that the failure load for a single weld joint is above 90N, indicating good weld mechanical properties. In practical applications, the weld stability of the Hastelloy foil 1 and the offshore wind turbine component 2 can be improved by adding multiple weld points.

[0045] In this embodiment, after welding with a circular resistance welding head, the surface of the Hastelloy foil 1 is intact, with no obvious welding marks, no cracks in the weld, and the surface of the Hastelloy foil 1 still has the same corrosion resistance as in the initial state.

[0046] In this embodiment, a flat resistance welding head is selected for welding, resulting in a narrow weld seam with a length of approximately 1 mm formed by several weld points. When using the flat resistance welding head, the welding current is preferably 30A-40A. When performing continuous spot welding with the flat resistance welding head, the weld point interval is 0.5 mm. Welding begins with a welding current of 30A for the first weld point, and the welding current for each subsequent weld point is increased by 30%-35% compared to the first weld point, set to approximately 40A. Continuous spot welding using this method can achieve the connection of the spot weld seams and seal the corrosion-resistant layer. Using a flat resistance welding head can effectively increase the weld seam length and reduce the weld seam width. The continuous weld seam obtained using a flat resistance welding head is as follows: Figure 6 As shown.

[0047] When using the resistance welding method for Hastelloy foil 1 in this embodiment, the resistance spot welding function of a cold welding machine is used. First, the offshore wind turbine assembly 2 and the Hastelloy foil 1 are pre-treated. The surfaces of the offshore wind turbine assembly 2 and the Hastelloy foil 1 are cleaned and trimmed to ensure the flatness of the contact surfaces. The offshore wind turbine assembly 2 is directly connected to the resistance welding ground cable. The Hastelloy foil 1 is placed on the smooth and flat surface of the offshore wind turbine assembly 2, and the resistance welding head 3 is vertically pressed onto the Hastelloy foil 1. After ensuring full contact between the Hastelloy foil 1 and the offshore wind turbine assembly 2, resistance welding is performed. The weld seam formed by this welding method is located at the contact surface between the Hastelloy foil 1 and the offshore wind turbine assembly 2. The welding does not damage the integrity of the contact surface between the Hastelloy foil 1 and the resistance welding head 3, avoiding damage to the corrosion resistance of the Hastelloy foil 1, isolating the offshore wind turbine assembly 2 from the corrosive marine environment, and improving the service life of the offshore wind turbine assembly 2.

[0048] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for welding Hastelloy foil based on resistance welding, characterized in that: Includes the following steps: Step 1: Pre-treat the structure to be welded and the Hastelloy foil; In step one, the thickness of the Hastelloy foil is between 0.06mm and 0.15mm, and the thickness of the structure to be welded is greater than 1mm. In step one, when pre-treating the structure to be welded and the Hastelloy foil, the structure to be welded is polished with 400-grit sandpaper, and the Hastelloy foil is polished with 2000-grit sandpaper. The polished structure to be welded and the Hastelloy foil are then cleaned with ethanol. Step 2: Use sandpaper to adjust the shape of the resistance welding head; Step 3: Clamp the grounding cable of the resistance welding equipment onto the structure to be welded, and place the Hastelloy foil at the welding position of the structure to be welded. In step three, either a round resistance welding head or a flat resistance welding head is selected. Step 4: Adjust the resistance welding current to complete the spot welding. In step four, the welding current used when selecting a round resistance welding head is 70A-90A, and the welding current used when selecting a flat resistance welding head is 30A-40A. In step four, during the welding process, the molten pool is located between the Hastelloy foil and the structure to be welded, and the melting thickness of the Hastelloy foil does not exceed two-thirds of the thickness of the Hastelloy foil.

2. The method for welding Hastelloy foil based on resistance welding according to claim 1, characterized in that: In step one, the Hastelloy foil is a Hastelloy C-276 foil.

3. The method for welding Hastelloy foil based on resistance welding according to claim 1, characterized in that: In step two, when adjusting the shape of the resistance welding head with sandpaper, the edges of the resistance welding head are polished smooth with 400-grit sandpaper to remove the sharp lines, and the welding contact surface of the resistance welding head is polished smooth and flat with 2000-grit sandpaper. The polished resistance welding head is then cleaned with ethanol.

4. The method for welding Hastelloy foil based on resistance welding according to claim 1, characterized in that: In step three, the Hastelloy foil is laid flat on the structure to be welded, and the resistance welding head is pressed vertically onto the Hastelloy foil.

5. The method for welding Hastelloy foil based on resistance welding according to claim 4, characterized in that: In step four, when using a flat resistance welding head for continuous spot welding, the interval between weld spots is 0.5mm. Welding starts from the first weld spot with a welding current of 30A, and the welding current of each subsequent weld spot is increased by 30%-35% compared to the first weld spot.

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