Method for controlling zinc deposition on the surface of a welded joint of a zinc-based plated steel sheet

Abstract

This invention discloses a method for controlling zinc buildup on the weld surface of zinc-based coated steel sheets, relating to the field of steel sheet welding, and mainly addressing the problem of zinc buildup defects easily occurring on the weld surface of zinc-based coated steel sheets after welding. The method includes: pre-applying an outer coating to the surfaces of a first zinc-based coated steel sheet and a second zinc-based coated steel sheet to obtain a first steel sheet and a second steel sheet; and performing resistance spot welding on the superimposed first and second steel sheets to form a target steel sheet, wherein the target steel sheet has a first end face and a second end face. This invention is used for controlling zinc buildup on the weld surface of zinc-based coated steel sheets.

Description

Technical Field

[0001] This invention relates to the field of steel plate welding, and more particularly to a method for controlling zinc buildup on the weld surface of zinc-based coated steel plates. Background Technology

[0002] To improve the corrosion resistance of car bodies, zinc-based coated steel sheets such as pure zinc (GI) and zinc-aluminum-magnesium (ZM) are widely used in car body manufacturing. Resistance spot welding is the most important connection process in car body manufacturing. In recent years, the automotive manufacturing industry has continuously increased its requirements for the appearance quality of weld points of visible parts. However, zinc-based coated steel sheets are prone to zinc accumulation defects on the surface of weld points after welding. In order to improve the appearance quality, the weld points must be manually ground before electrophoresis to eliminate the protrusions. The grinding process for zinc accumulation defects in weld points will bring the following problems: (1) manual grinding will increase manufacturing costs and reduce production efficiency; (2) grinding will damage the zinc-based coating around the weld point and reduce corrosion resistance; (3) the reduction of corrosion resistance around the weld point will further affect the load-bearing safety of the weld point. Summary of the Invention

[0003] In view of the above problems, the present invention provides a method for controlling zinc buildup on the surface of weld joints of zinc-based coated steel sheets, the main purpose of which is to solve the problem that zinc buildup defects easily occur on the surface of weld joints after welding of zinc-based coated steel sheets.

[0004] To solve at least one of the above-mentioned technical problems, in a first aspect, the present invention provides a method for controlling zinc buildup on the weld surface of zinc-based coated steel sheets, the method comprising:

[0005] The first and second zinc-based coated steel sheets are respectively pre-coated with external coatings to obtain the first steel sheet and the second steel sheet;

[0006] The first and second steel plates, which are stacked together, are subjected to resistance spot welding to form a target steel plate, wherein the target steel plate has a first end face and a second end face.

[0007] Optionally, the melting point of the outer coating is greater than that of the zinc-based coating.

[0008] Optionally, the first end face mentioned above is an exposed surface, and the resistance spot welding of the stacked first and second steel plates to form the target steel plate includes:

[0009] The first electrode is brought into contact with the first end face and the second electrode is brought into contact with the second end face, and resistance spot welding is performed to form the target steel plate.

[0010] Optionally, the above method further includes: increasing the diameter and end face radius of curvature of the first electrode and the second electrode to perform resistance spot welding on the superimposed first steel plate and second steel plate to form the target steel plate.

[0011] Optionally, the end face diameter of the first electrode is larger than the end face diameter of the second electrode, and / or the end face radius of curvature of the first electrode is larger than the end face radius of curvature of the second electrode.

[0012] Optionally, the end face diameter of the first electrode is greater than 6 mm and less than 16 mm, and the end face diameter of the second electrode is greater than or equal to 6 mm and less than 8 mm.

[0013] Optionally, the end face radius of curvature of the first electrode is greater than 40 mm, and the end face radius of curvature of the second electrode is greater than or equal to 40 mm and less than 60 mm.

[0014] Optionally, the material of the outer coating is nickel or chromium.

[0015] Optionally, the above method further includes: pre-forming an external coating on the surface of the first zinc-based coated steel sheet and the second zinc-based coated steel sheet based on any one of electroplating, electroless plating and vapor deposition.

[0016] Optionally, the thickness of the outer coating and the thickness of the zinc-based coating satisfy a preset thickness relationship, wherein the preset thickness relationship is h2≤0.3h1, where h2 is the thickness of the outer coating and h1 is the thickness of the zinc-based coating.

[0017] By employing the above technical solution, the present invention provides a method for controlling zinc buildup on the weld surface of zinc-based coated steel sheets. Addressing the problem of zinc buildup defects easily occurring on the weld surface after welding of zinc-based coated steel sheets, the present invention obtains a first steel sheet and a second steel sheet by pre-forming an outer coating on the surfaces of the first and second zinc-based coated steel sheets, respectively. The stacked first and second steel sheets are then resistance-spot welded to form a target steel sheet, wherein the target steel sheet has a first end face and a second end face. In this solution, by pre-forming an outer coating on the surface of the zinc-based coated steel sheet, the outer coating does not melt during welding and cannot fully react with the zinc-based coating at the moment of welding. Therefore, an effective seal is formed on the surface of the low-melting-point zinc-based coating. Even if some of the low-melting-point zinc-based coating penetrates the high-melting-point outer coating to reach the weld surface during resistance spot welding, the volume of the zinc-based coating reaching the surface is significantly reduced compared to having no outer coating. After accumulation and cooling, no obvious zinc buildup defects are formed.

[0018] Accordingly, the zinc deposit control device, equipment, and computer-readable storage medium for the weld surface of zinc-based coated steel sheets provided in the embodiments of the present invention also have the above-mentioned technical effects.

[0019] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0021] Figure 1 A flowchart illustrating a method for controlling zinc buildup on the weld surface of a zinc-based coated steel sheet according to an embodiment of the present invention is shown.

[0022] Figure 2 This diagram illustrates the composition of a target steel plate according to an embodiment of the present invention.

[0023] Figure 3 This diagram illustrates the experimental results of a method for controlling zinc buildup on the weld surface of a zinc-based coated steel sheet when the first and second electrodes are of the same size, according to an embodiment of the present invention.

[0024] Figure 4 This diagram illustrates the test results of a zinc-based coated steel sheet without a pre-formed outer coating, according to an embodiment of the present invention.

[0025] Figure 5 The diagram shows the experimental results of a method for controlling zinc buildup on the weld surface of a zinc-based coated steel sheet when the first and second electrodes have different dimensions, according to an embodiment of the present invention. Detailed Implementation

[0026] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0027] To address the problem of zinc buildup defects on the weld surface of zinc-based coated steel sheets after welding, this invention provides a method for controlling zinc buildup on the weld surface of zinc-based coated steel sheets, such as... Figure 1 As shown, the method includes:

[0028] S101, respectively, an outer coating is pre-formed on the surface of the first zinc-based coated steel sheet and the second zinc-based coated steel sheet to obtain the first steel sheet and the second steel sheet;

[0029] For example, embodiments of the present invention pre-form an external coating on the surface of a zinc-based coated steel sheet to increase the melting point of the coating surface, thereby achieving the functions of isolation and sealing. It is understood that the pre-formation of the external coating on the zinc-based coating surface described in the present invention can be a double-sided pre-formation or a single-sided pre-formation.

[0030] S102. Resistance spot welding is performed on the superimposed first steel plate and second steel plate to form a target steel plate, wherein the target steel plate has a first end face and a second end face.

[0031] For example, in this embodiment of the invention, a resistance spot welding device is used to weld the stacked first and second steel plates. During the welding process, at least one electrode of the resistance spot welding device is in contact with the pre-formed outer coating. Under the action of the welding current, weld nuggets are formed between the test plates of the target steel plate. It is understood that the resistance spot welding device is a power frequency spot welding device, a medium frequency spot welding device, etc., and the target steel plate is the target steel plate.

[0032] By employing the above technical solution, the present invention provides a method for controlling zinc buildup on the weld surface of zinc-based coated steel sheets. Addressing the problem of zinc buildup defects easily occurring on the weld surface after welding of zinc-based coated steel sheets, the present invention obtains a first steel sheet and a second steel sheet by pre-forming an outer coating on the surfaces of the first and second zinc-based coated steel sheets respectively; resistance spot welding is then performed on the stacked first and second steel sheets to form a target steel sheet, wherein the target steel sheet has a first end face and a second end face. In the above solution, by pre-forming an outer coating on the zinc-based coating surface of the visible test plate in the target steel sheet, since the outer coating does not melt during welding and cannot fully react with the zinc-based coating at the moment of welding, an effective seal is formed on the surface of the low-melting-point zinc-based coating. Even if some of the low-melting-point zinc-based coating penetrates the high-melting-point outer coating to reach the weld surface during resistance spot welding, the volume of the zinc-based coating reaching the surface is significantly reduced compared to having no outer coating, and after cooling, no obvious zinc buildup defects are formed.

[0033] In one embodiment, the melting point of the outer coating is greater than the melting point of the zinc-based coating.

[0034] For example, in this embodiment of the invention, an outer coating is pre-formed on the surface of the zinc-based coating, such that the melting point T2 of the outer coating is greater than the melting point T1 of the zinc-based coating. Because the melting point of the outer coating is increased, the volume of the coating melting around the solder joint is reduced. After the zinc-based coating melts, it is sealed between the high-melting-point outer coating and the substrates of the first and second steel plates, thereby reducing the flow of the low-melting-point zinc-based coating.

[0035] In one embodiment, the first end face is an exposed surface, and the resistance spot welding of the stacked first and second steel plates to form the target steel plate includes:

[0036] The first electrode is brought into contact with the first end face and the second electrode is brought into contact with the second end face, and resistance spot welding is performed to form the target steel plate.

[0037] For example, in this embodiment of the invention, two or more steel plates are stacked and overlapped to form a target steel plate. The first end face of the target steel plate is designated to have appearance quality requirements.

[0038] In one embodiment, the method further includes: increasing the diameter and end face radius of curvature of the first electrode and the second electrode to perform resistance spot welding on the superimposed first steel plate and second steel plate to form a target steel plate.

[0039] For example, by using spot welding electrodes with large end face diameter and large radius of curvature on the visible side, the surface current density of the test plate with pre-formed outer coating is reduced, while the heat dissipation area is increased, further reducing the surface temperature and reducing the melting of zinc-based coating.

[0040] Furthermore, by using spot welding electrodes with large end face diameters and large radii of curvature on the exposed surface, the pressure on the target steel plate on the exposed surface is reduced. At the same time, the reduction in the surface temperature of the weld point increases the support force on the surface of the target steel plate, which can reduce the depth of the weld indentation on the exposed surface, thereby further improving the appearance quality of the weld point.

[0041] In one embodiment, the end face diameter of the first electrode is greater than the end face diameter of the second electrode, and / or the end face radius of curvature of the first electrode is greater than the end face radius of curvature of the second electrode.

[0042] For example, the total thickness of the target steel plate is t, and the thickness of the thinnest test plate in the target steel plate is t1. When the thickness ratio t / t1≤3, the diameter d1 and radius of curvature r1 of the first electrode end face in contact with the thin test plate, and the diameter d2 and radius of curvature r2 of the second electrode end face in contact with the test plate on the other side of the target steel plate, need to satisfy d1≥d2 and r1≥r2.

[0043] In one embodiment, the end face diameter of the first electrode is greater than 6 mm and less than 16 mm, and the end face diameter of the second electrode is greater than or equal to 6 mm and less than 8 mm.

[0044] In one embodiment, the end face radius of curvature of the first electrode is greater than 40 mm, and the end face radius of curvature of the second electrode is greater than or equal to 40 mm and less than 60 mm.

[0045] For example, by employing differentiated electrodes with different end face diameters and radii of curvature, the following effects are achieved: (1) Since the total current flowing through the two electrode end faces is the same, a larger electrode end face diameter and / or a larger radius of curvature increases the contact area between the electrode and the steel plate, resulting in a decrease in surface current density; (2) a larger electrode end face diameter and / or a larger radius of curvature increases the contact area between the electrode and the steel plate, resulting in increased surface heat dissipation; (3) a larger electrode end face diameter and / or a larger radius of curvature increases the contact area between the electrode and the steel plate, resulting in a decrease in surface pressure. These effects, combined, cause the final weld nugget to shift towards the side with a smaller electrode end face diameter and / or a smaller radius of curvature, thereby reducing the surface temperature of the weld point on the side with a larger electrode end face diameter and / or a larger radius of curvature, further reducing zinc buildup defects. When the thick plate surface has appearance requirements (i.e., the thick plate is the first steel plate), weld nugget shifting is beneficial for weld nugget formation. When the thin plate has appearance requirements (i.e., the thin plate is the first steel plate), when the thickness ratio t / t1 ≤ 3, the weld nugget offset will not significantly affect the weld nugget formation at the interface between the two steel plates; when the thickness ratio t / t1 > 3, the weld nugget offset will affect the weld nugget formation at the interface. Therefore, when the thin plate is used as the first steel plate, the thickness ratio t / t1 is limited to ≤ 3.

[0046] In one embodiment, the material of the outer coating is nickel or chromium.

[0047] For example, compared to zinc's melting point of 419.53°C, nickel is a hard, ductile, and ferromagnetic metal that can be highly polished and is corrosion-resistant, with a melting point of 1453°C, making it suitable for outer plating. Chromium, with a melting point of 1907°C, is also suitable.

[0048] In one embodiment, the method further includes: pre-forming an external coating on the surface of the first zinc-based coated steel sheet and the second zinc-based coated steel sheet based on any one of electroplating, electroless plating, and vapor deposition.

[0049] For example, electroplating is a process of depositing a thin layer of other metals or alloys onto the surface of a steel plate using the principle of electrolysis. It is a process that uses electrolysis to attach a metal film to the surface of metal or other material parts, thereby preventing metal oxidation, improving wear resistance, conductivity, reflectivity, corrosion resistance, and enhancing aesthetics.

[0050] Like electroplating, electroless plating also involves a redox reaction where metal ions in the plating solution are reduced to atoms and adhere to the surface of the magnet. However, unlike electroless plating, there is no electric current to attract ions and enhance atomic adhesion. Therefore, a reducing agent is required to coexist in the plating solution, and a catalyst is also needed on the substrate surface. This process can form a uniform outer coating on the surface of magnets with complex shapes. The outer coating has high hardness, small porosity, and high chemical stability.

[0051] The advantages of vapor deposition are high ionization rate (up to 100%), high deposition rate, intense bombardment, dense outer coating and good bonding with the substrate.

[0052] In one embodiment, the thickness of the outer coating and the thickness of the zinc-based coating satisfy a preset thickness relationship, wherein the preset thickness relationship is h2≤0.3h1, where h2 is the thickness of the outer coating and h1 is the thickness of the zinc-based coating.

[0053] For example, the thickness of the outer coating is h2, and the thickness of the zinc-based coating is h1, satisfying h2≤0.3h1.

[0054] In summary, this application, by pre-applying a high-melting-point coating to a visible test panel with aesthetic requirements, suppresses zinc buildup defects during the welding process without affecting welding quality. During resistance spot welding, the surface temperature of the weld joint can reach approximately 900°C, far exceeding the melting point of the zinc-based coating. The molten zinc-based coating is squeezed out around the weld joint under electrode pressure. In many cases, the magnetic field around the weld joint is not uniform; under the influence of electromagnetic force, the squeezed-out zinc-based coating metal aggregates and solidifies to form zinc buildup. In this embodiment of the invention, a high-melting-point outer coating is pre-applied to the surface of the low-melting-point zinc-based coating before welding. Because the melting point of the outer coating is higher than the surface temperature of the weld joint, it does not melt during welding and cannot fully react with the zinc-based coating at the moment of welding. Therefore, an effective seal is formed on the surface of the low-melting-point zinc-based coating. Even during resistance spot welding, when some low-melting-point zinc-based plating penetrates the high-melting-point outer plating to reach the weld surface, the volume of zinc-based plating reaching the surface is significantly reduced compared to when there is no outer plating. This reduced volume prevents the formation of noticeable zinc buildup defects upon cooling. Furthermore, using electrodes with large end-face diameters and radii of curvature on the visible surface (outer surface of the part) further reduces the current density and pressure on the visible surface during welding, lowering the temperature and further suppressing zinc buildup defects. The reduced pressure also prevents indentations during welding, resulting in low-indentation welds and improved appearance. In addition, this technology extends electrode lifespan. Typically, electrode materials are copper alloys, such as chromium-zirconium copper and alumina-dispersion-strengthened copper. At high welding temperatures, Zn on the material surface reacts with Cu to form a zinc-copper alloy, reducing electrode lifespan. The high-melting-point pre-plating layer, to some extent, inhibits the contact and reaction between Zn and Cu, preventing contamination of the electrode by the low-melting-point zinc-based plating and extending electrode lifespan.

[0055] Furthermore, to further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, such as... Figures 2-5 As shown in the examples below, the implementation process for controlling zinc buildup on the weld surface of zinc-based coated steel sheets in two embodiments of the present invention is illustrated. Figure 2As shown, the first zinc-based coated steel plate 1, the first zinc-based coated steel plate substrate 11, the first zinc-based coating 12, the first zinc-based coated steel plate outer coating 13, the second zinc-based coated steel plate 2, the second zinc-based coated steel plate substrate 21, the second zinc-based coating 22, the target steel plate 3, the first electrode 4, and the second electrode 5.

[0056] Example 1:

[0057] The target steel plate 3 is composed of a first zinc-based coated steel plate 1 and a second zinc-based coated steel plate 2.

[0058] The first zinc-based coated steel plate 1 includes a first zinc-based coated steel plate substrate 11 and a first zinc-based coating 12. In this embodiment of the invention, the first zinc-based coated steel plate substrate 11 is IF steel with a thickness of 0.7 mm. The first zinc-based coating 12 is located on both sides of the first zinc-based coated steel plate substrate 11 and is a zinc-aluminum-magnesium coating with a coating thickness of 5 μm on each side. The aluminum content is 1-2%, the magnesium content is 1-2%, and the remaining element is zinc. The melting point T1 of the first zinc-based coating 12 is approximately 380°C.

[0059] The second zinc-based coated steel plate 2 includes a first zinc-based coated steel plate substrate 21 and a first zinc-based coating 12. In this embodiment of the invention, the second zinc-based coated steel plate substrate 21 is IF steel with a thickness of 0.7 mm. The second zinc-based coating 22 is located on both sides of the second zinc-based coated steel plate substrate 21 and is a zinc-aluminum-magnesium coating with a single-sided coating thickness of 5 μm. The aluminum content is 1-2%, the magnesium content is 1-2%, and the remaining element is zinc. The melting point T1 of the second zinc-based coating 22 is approximately 380°C.

[0060] To reduce zinc buildup defects during welding, the first zinc-based coated steel plate 1 and the second zinc-based coated steel plate 2 were pretreated before welding. Electroplating was used to coat the outer surface of the first zinc-based coated steel plate 1 with a Ni composition. The thickness of the outer coating on one side was 0.05 μm, and its melting point T2 was 1453℃, much higher than the melting point of the zinc-based coating. Electroplating was also used to coat the outer surface of the first zinc-based coated steel plate 2 with a Ni composition. The thickness of the outer coating on one side was also 0.05 μm, and its melting point T2 was 1453℃, much higher than the melting point of the zinc-based coating. At this point, the thickness of the outer coating was h2, and the thickness of the zinc-based coating was h1, satisfying h2 ≤ 0.3h1.

[0061] After preparing the outer coating, the first zinc-based coated steel plate 1 and the second zinc-based coated steel plate 2 are overlapped to form the target steel plate 3. The target steel plate 3 is then welded using a resistance spot welding device. The resistance spot welding device is a medium-frequency DC welding machine, and the welding equipment includes a first electrode 4 and a second electrode 5.

[0062] In this embodiment, the first electrode 4 and the second electrode 5 are identical in size: the first electrode 4 has an end face diameter of 6mm and an end face curvature radius of 40mm; the second electrode 5 has an end face diameter of 6mm and an end face curvature radius of 40mm, and is made of chromium zirconium copper. The first electrode 4 contacts the outer coating 13 of the first zinc-based coated steel plate 1 on the upper surface of the first zinc-based coated steel plate 1; the second electrode 5 contacts the outer coating of the second zinc-based coated steel plate 2 on the lower surface of the second zinc-based coated steel plate 2. The welding parameters are: welding pressure 3kN, welding time 300ms, and welding current 8kA. After welding, a weld nugget is formed between the first zinc-based coated steel plate 1 and the second zinc-based coated steel plate 2, achieving the connection between the first zinc-based coated steel plate 1 and the second zinc-based coated steel plate 2. In this embodiment, the final weld nugget diameter is 5.5mm, and the failure mode of the weld nugget in the peel test is button failure, meeting the usage requirements. The appearance quality of the weld joint is as follows: Figure 3 As shown, no zinc buildup defects occurred around the solder joints. Through continuous welding tests, with a 2-second time interval between each two solder joints, the electrode life after the surface pre-applied high-melting-point coating was examined. The tested electrode life reached 3000 points.

[0063] Comparative Example 1:

[0064] In Comparative Example 1, no external coating was pre-applied to the surfaces of the first zinc-based coated steel plate 1 and the second zinc-based coated steel plate before welding; all other conditions were identical to those in Example 1. In Comparative Example 1, the final weld nugget diameter was 5.5 mm, and the weld nugget failure mode in the peel test was button failure, indicating that the mechanical properties met the usage requirements. The appearance quality of the weld joint was as follows: Figure 4 As shown, there are obvious zinc build-up defects around the weld points. Through continuous welding tests, with a time interval of 2 seconds between every two weld points, the electrode life was tested at 2000 points, which is significantly lower than that of the steel plate after pre-coating.

[0065] Example 2:

[0066] The target steel plate 3 is composed of a first zinc-based coated steel plate 1 and a second zinc-based coated steel plate 2.

[0067] The first zinc-based coated steel plate 1 includes a first zinc-based coated steel plate substrate 11 and a first zinc-based coating 12. In this embodiment of the invention, the first zinc-based coated steel plate substrate 11 is IF steel with a thickness of 0.7 mm. The first zinc-based coating 12 is located on both sides of the first zinc-based coated steel plate substrate 11 and is a zinc-aluminum-magnesium coating with a coating thickness of 5 μm on each side. The aluminum content is 1-2%, the magnesium content is 1-2%, and the remaining element is zinc. The melting point T1 of the first zinc-based coating 12 is approximately 380°C.

[0068] The second zinc-based coated steel plate 2 includes a first zinc-based coated steel plate substrate 21 and a first zinc-based coating 12. In Embodiment 2 of the present invention, the second zinc-based coated steel plate substrate 21 is IF steel with a thickness of 0.7 mm. The second zinc-based coating 22 is located on both sides of the second zinc-based coated steel plate substrate 21 and is a zinc-aluminum-magnesium coating with a single-sided coating thickness of 5 μm. The aluminum content is 1-2%, the magnesium content is 1-2%, and the remaining element is zinc. The melting point T1 of the second zinc-based coating 22 is approximately 380°C.

[0069] To reduce zinc buildup defects during welding, the first zinc-based coated steel plate 1 was pretreated before welding by electroplating. An outer coating 13, composed of Ni, was applied to both sides of the first zinc-based coated steel plate 1. The coating thickness on each side was 0.05 μm, and its melting point T2 was 1453℃, significantly higher than the melting point of the zinc-based coating. At this point, the thickness of the outer coating was h2, and the thickness of the zinc-based coating was h1, satisfying h2 ≤ 0.3h1.

[0070] After preparing the outer coating, the first zinc-based coated steel plate 1 and the second zinc-based coated steel plate 2 are overlapped to form the target steel plate 3. The target steel plate 3 is then welded using a resistance spot welding device. One side of the first zinc-based coated steel plate 1 is the visible surface and has appearance quality requirements. Specifically, in Embodiment 2 of the present invention, the resistance spot welding device is a medium-frequency DC welding machine, and the welding equipment includes a first electrode 4 and a second electrode 5.

[0071] In this embodiment, the first electrode 4 and the second electrode 5 have different dimensions: the first electrode 4 has an end face diameter of 10mm and a flat end face; the second electrode 5 has an end face diameter of 6mm and an end face radius of curvature of 40mm. In this embodiment, the total thickness of the target steel plate 3 is t, which is 1.4mm, and the thickness of the thinnest test plate in the target steel plate is t1, which is 0.7mm. The thickness ratio t / t1 = 2 (satisfying the thickness ratio t / t1 ≤ 3, the weld nugget offset is small). At this time, the end face diameter d1 and radius of curvature r1 of the first electrode 4 in contact with the first zinc-based coated steel plate 1, and the end face diameter d2 and radius of curvature r2 of the second electrode 5 in contact with the second zinc-based coated steel plate 2, satisfy d1 ≥ d2 and r1 ≥ r2.

[0072] The first electrode 4 contacts the outer coating 13 of the first zinc-based coated steel plate 1 on its upper surface; the second electrode 5 contacts the second zinc-based coated steel plate 22 on its lower surface. The welding parameters are: welding pressure 3kN, welding time 300ms, and welding current 10kA. After welding, a weld nugget is formed between the first zinc-based coated steel plate 1 and the second zinc-based coated steel plate 2, achieving the connection between them. In this embodiment, the final weld nugget diameter is 6.1mm, and the weld nugget failure mode in the peel test is button failure, meeting the usage requirements. The appearance quality of the weld joint is as follows: Figure 5As shown, no zinc buildup defects occurred around the weld points. The outer surface of the first zinc-based coated steel sheet 1 had no obvious indentations, felt smooth to the touch, and its appearance quality was further improved.

[0073] In this application, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise expressly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can mean a fixed connection, a detachable connection, or an integral connection; "link" can mean a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0074] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0075] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0076] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0077] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0078] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0079] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0080] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0081] This application also provides a computer program product, which includes computer software instructions that, when executed on a processing device, cause the processing device to perform actions such as... Figure 1 The control flow of the memory in the corresponding embodiment.

[0082] A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can store or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk (SSD)).

[0083] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0084] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between apparatuses or units, and may be electrical, mechanical, or other forms.

[0085] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0086] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0087] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0088] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for controlling zinc buildup on the weld joint surface of a zinc-based coated steel sheet, characterized in that, include: The first and second zinc-based coated steel sheets are respectively pre-coated with external coatings to obtain the first steel sheet and the second steel sheet; The first and second steel plates, which are stacked together, are subjected to resistance spot welding to form a target steel plate, wherein the target steel plate has a first end face and a second end face; The melting point of the outer coating is greater than that of the zinc-based coating. The outer coating does not melt during the welding process and cannot fully react with the zinc-based coating at the moment of welding. The first end face is an exposed surface, and the first end face is pre-coated with the aforementioned outer coating. The step of resistance spot welding the stacked first and second steel plates to form the target steel plate includes: The first electrode is brought into contact with the first end face and the second electrode is brought into contact with the second end face, and resistance spot welding is performed to form the target steel plate. The thickness of the outer coating and the thickness of the zinc-based coating satisfy a preset thickness relationship, wherein the preset thickness relationship is h2≤0.3h1, where h2 is the thickness of the outer coating and h1 is the thickness of the zinc-based coating; The material of the outer plating layer is nickel or chromium; An external coating is pre-formed on the surface of the first zinc-based coated steel sheet and the second zinc-based coated steel sheet using any one of the following methods: electroplating, electroless plating, and vapor deposition. The diameter of the end face of the first electrode is larger than the diameter of the end face of the second electrode. And / or, The radius of curvature of the end face of the first electrode is greater than that of the end face of the second electrode.

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