Welding methods for Al-Mg-Sc alloy plates

Abstract

This invention provides a welding method for Al-Mg-Sc alloy plates, which involves gas metal arc welding (GMAW) of the Al-Mg-Sc alloy plates. Let the thickness of the Al-Mg-Sc alloy plate be W. When 1mm ≤ W ≤ 4mm, the GMAW welding current is 62A~100A, the welding voltage is 15V~20V, and the welding speed is 0.4m / min~0.8m / min. When 4mm < W ≤ 10mm, a symmetrical V-groove is machined at the welding interface of the Al-Mg-Sc alloy plate, and the GMAW welding current is 160A~200A, the welding voltage is 21V~25V, and the welding speed is 0.5m / min~1.0m / min. This invention can obtain high-quality welded joints with high tensile strength, high elongation, and high weldability coefficients under different thickness specifications.

Description

Technical Field

[0001] This invention relates to the field of alloy welding technology, and more specifically, to a welding method for Al-Mg-Sc alloy plates. Background Technology

[0002] Aluminum alloys, with their excellent specific strength, good corrosion resistance, and convenient processing performance, have become indispensable key structural materials in high-end equipment fields such as aerospace, high-speed rail transportation, marine engineering, and shipbuilding. However, the bottleneck of balancing strength and weldability in traditional Al-Mg alloys is gradually becoming apparent. Meanwhile, 5-series aluminum-magnesium alloys, due to their moderate strength, good weldability, and resistance to seawater corrosion, are widely used in load-bearing structural components.

[0003] Despite the significant application potential of 5-series alloys in terms of their intrinsic material properties, controlling the welding process remains challenging in the actual manufacturing and joining of thin-plate components. Aluminum alloy welding generally faces inherent difficulties such as high thermal conductivity, high specific heat capacity, low high-temperature strength, and susceptibility to oxidation. Especially when welding medium-thin plates with thicknesses ranging from 1mm to 10mm, controlling the heat input is crucial. Excessive heat input can easily lead to burn-through, molten pool collapse, or significant welding deformation; insufficient heat input may result in incomplete fusion, incomplete penetration, or poor weld formation. Furthermore, the solubility of hydrogen in aluminum alloys varies drastically with temperature; during cooling and solidification, hydrogen readily precipitates, forming pores that severely affect the joint's density and mechanical properties.

[0004] Currently, there are relatively mature standards for welding processes of conventional 5-series aluminum alloys (such as 5083 and 5052), mainly employing MIG (Metal Inert Gas) or TIG (Tungsten Inert Gas) technologies. However, Al-Mg-Sc alloys, as a novel alloy containing trace amounts of Sc, exhibit significant differences in molten pool flow behavior, metallurgical reaction patterns, and microstructure evolution mechanisms compared to traditional Al-Mg alloys. Existing general welding process parameters are often not directly applicable to Al-Mg-Sc alloys. Directly applying traditional processes often results in severe joint softening, high porosity, and a high tendency to crack. Particularly in the processing of plates of varying thicknesses, existing technologies lack systematic and differentiated process guidance. For ultra-thin and thin plates of 1mm to 4mm, traditional processes often struggle to balance penetration and burn-through prevention, and require extremely high stability of the shielding gas. For medium-thickness plates of 4mm to 10mm, single-pass welding or improper beveling design can easily lead to incomplete fusion defects at the root. Furthermore, without optimization of interpass temperature control and heat accumulation effects during multi-pass welding, grain coarsening can occur, reducing joint toughness. In addition, existing welding standards are largely based on traditional alloys and do not fully consider the influence of Sc on the surface tension of the molten pool, as well as its specific sensitivity to the purity and flow rate of the shielding gas.

[0005] Therefore, how to provide a welding process suitable for medium-strength weldable Al-Mg-Sc alloy plates, so as to accurately match welding parameters for different thickness specifications (1mm~10mm), thereby effectively suppressing defects such as porosity, cracks and lack of fusion, and obtaining high-quality welded joints, is a technical problem that needs to be solved in this field. Summary of the Invention

[0006] The main objective of this invention is to provide a welding method for Al-Mg-Sc alloy plates, in order to solve the problems of poor welding effect and poor mechanical properties of welded joints in the prior art.

[0007] To achieve the above objectives, this invention provides a welding method for Al-Mg-Sc alloy plates, employing a flat butt joint method for gas metal arc welding (GMAW) of the Al-Mg-Sc alloy plates. The thickness of the Al-Mg-Sc alloy plate is denoted as W, where 1mm ≤ W ≤ 10mm. When 1mm ≤ W ≤ 4mm, the GMAW welding current is 62A~100A, the welding voltage is 15V~20V, and the welding speed is 0.4m / min~0.8m / min. When 4mm < W ≤ 10mm, a symmetrical V-groove is machined at the welding interface of the Al-Mg-Sc alloy plate, and the GMAW welding current is 160A~200A, the welding voltage is 21V~25V, and the welding speed is 0.5m / min~1.0m / min.

[0008] Furthermore, by mass percentage, the Al-Mg-Sc alloy sheet comprises 3.5 wt.% to 6.0 wt.% Mg, 0.08 wt.% to 0.30 wt.% Sc, 0.08 wt.% to 0.15 wt.% Zr, 0.05 wt.% to 0.5 wt.% Mn, 0 wt.% to 0.2 wt.% Cu, 0.01 wt.% to 0.4 wt.% Zn, 0 wt.% to 0.4 wt.% Fe, 0 wt.% to 0.2 wt.% Si, 0 wt.% to 0.1 wt.% Cr, and 0 wt.% to 0.2 wt.% Ti, with the balance being Al and unavoidable impurity elements.

[0009] Furthermore, the flow rate of the shielding gas used in gas metal arc welding is 15L / min to 28L / min.

[0010] Furthermore, when 1mm≤W≤4mm, the welding current used for gas metal arc welding is 62A~81A and the welding voltage is 16±1V; when 4mm<W≤10mm, the welding current used for gas metal arc welding is 170A~190A and the welding voltage is 23±1V.

[0011] Furthermore, when 4mm < W ≤ 10mm, the single-sided angle of the V-groove is 15°~30°, and the welding assembly gap is 0.5mm~2mm.

[0012] Furthermore, when 4mm < W ≤ 10mm, a welding sequence of one pass followed by two passes is adopted, with the welding assembly gap of the first pass being 0.5mm to 1.0mm and the welding assembly gap of the last two passes being 1.5mm to 2.0mm each independently.

[0013] Furthermore, the welding wire used in gas metal arc welding is an Al-Mg-Sc series welding wire, and by mass percentage, the Al-Mg-Sc series welding wire includes 5.8wt.%~6.8wt.% Mg, 0.3wt.%~0.50wt.% Sc, 0.08wt.%~0.15wt.% Zr, 0wt.%~0.3wt.% Mn, 0wt.%~0.1wt.% Cu, 0wt.%~0.3wt.% Zn, 0wt.%~0.3wt.% Fe, 0wt.%~0.2wt.% Si, 0wt.%~0.3wt.% Cr, and 0wt.%~0.05wt.% Ti, with the balance being Al and unavoidable impurity elements.

[0014] Furthermore, gas metal arc welding is performed under conditions of temperature ≥0℃ and relative humidity ≤85%RH.

[0015] Furthermore, before performing gas metal arc welding (GMAW), the Al-Mg-Sc alloy sheet is formed by rolling; the welding direction of GMAW is parallel or perpendicular to the rolling extension direction.

[0016] Furthermore, after gas metal arc welding, an Al-Mg-Sc alloy welded joint is formed, and the yield strength of the Al-Mg-Sc alloy welded joint is 150MPa~250MPa, the tensile strength is 260MPa~330MPa, the elongation is 4%~12%, and the welding coefficient is 0.75~0.95.

[0017] By applying the technical solution of this invention, Al-Mg-Sc alloy plates with a thickness of 1mm to 10mm are welded based on gas metal arc welding (MIG welding). By limiting the welding parameters for thin plates of 1mm≤W≤4mm and for medium-thick plates of 4mm<W≤10mm, the defects of burn-through in thin plates and lack of fusion in medium-thick plates are effectively avoided, while optimizing the weld formation quality. Thus, high-quality welded joints with high tensile strength, high elongation and high weld coefficient can be obtained under different thickness specifications. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 and Figure 2 This is a grain structure diagram of the Al-Mg-Sc alloy welded joint formed in Example 1 of the present invention;

[0020] Figure 3 and Figure 4 This is a grain structure diagram of the Al-Mg-Sc alloy welded joint formed in Example 2 of the present invention;

[0021] Figure 5 This is a grain structure diagram of the Al-Mg-Sc alloy welded joint formed in Comparative Example 1 of the present invention. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0023] As described in the background section, existing technologies suffer from poor welding results and poor mechanical properties in Al-Mg-Sc alloy plates. To address these issues, this invention provides a welding method for Al-Mg-Sc alloy plates, employing a flat butt joint method with gas metal arc welding (GMAW). The thickness of the Al-Mg-Sc alloy plate is denoted as W, where 1mm ≤ W ≤ 10mm. When 1mm ≤ W ≤ 4mm, the GMAW welding current is 62A~100A, the welding voltage is 15V~20V, and the welding speed is 0.4m / min~0.8m / min. When 4mm < W ≤ 10mm, a symmetrical V-groove is machined at the welding interface of the Al-Mg-Sc alloy plate, and the GMAW welding current is 160A~200A, the welding voltage is 21V~25V, and the welding speed is 0.5m / min~1.0m / min.

[0024] The welding method provided by this invention solves the problems of deformation / burn-through in thin plates and lack of fusion / incomplete penetration in thick plates by precisely limiting the welding heat input parameters in different thickness ranges. At the same time, it fully utilizes the grain refinement advantage of Sc element, and finally achieves efficient, stable and high-quality welding of Al-Mg-Sc alloy plates.

[0025] It's worth noting that thinner sheet metal is more sensitive to heat input. Therefore, relatively low current and voltage are used to reduce heat input and avoid problems such as molten pool collapse or burn-through. As the thickness increases, the current and heat input are moderately increased to ensure full penetration. During each welding pass, the molten pool exists for a short time, and the gas escape time is limited. By limiting the upper limit of heat input and using high-purity argon gas protection, combined with an appropriate welding speed, porosity can be effectively suppressed, and the performance of the weld joint can be improved.

[0026] Based on this, for thin plates (1mm≤W≤4mm), the welding current (62A~100A), voltage (15V~20V), and speed (0.4m / min~0.8m / min) defined in this invention together determine a relatively low and stable heat input range. For thin plates of 1~4mm, if the heat input is too high, the heat is rapidly conducted to the base material, resulting in an excessively large molten pool volume, collapse under gravity, or even burn-through. The aforementioned precise low current / voltage combination limits the heat input per unit length, ensuring a moderate molten pool size and sufficient surface tension to maintain the molten pool shape and prevent collapse. At the same time, the lower welding heat input reduces the residence time of the heat-affected zone at high temperatures. This helps suppress the coarsening and dissolution of Al3(Sc,Zr) precipitates, thereby retaining more fine-grain strengthening effect during post-weld cooling and maintaining the strength of the joint matrix.

[0027] For medium-thick plates (4mm < W≤10mm), the welding current (160A~200A), voltage (21V~25V), and speed (0.5m / min~1.0m / min) specified in this invention solve the problems of root incomplete fusion, incomplete penetration, and interlayer inclusions in thick plate welding; it also ensures the uniformity of chemical composition and mechanical properties of the weld metal. For plates of 4~10mm, the higher current and voltage increase the arc power and penetration depth, ensuring complete fusion and avoiding root incomplete penetration. The higher heat input also enhances the convection motion of the molten pool, which is beneficial to the uniform distribution of alloying elements such as Sc in the weld metal and promotes the uniform nucleation of Al3Sc nano-precipitates. At the same time, the appropriate speed (0.5~1.0m / min) ensures that the molten pool has sufficient time for metallurgical reactions (such as gas escape) while avoiding excessively coarse grains caused by excessively slow speed.

[0028] In summary, the above welding scheme, by dividing the thickness W into two sub-ranges and matching different heat inputs to each, demonstrates the targeted and adaptable nature of the process parameters. This overcomes the contradiction that uniform process parameters cannot simultaneously satisfy the requirements of preventing burn-through in thin plates and ensuring penetration in thick plates. The resulting welded joint possesses excellent mechanical properties, maintaining the high strength and high corrosion resistance characteristic of Al-Mg-Sc alloys.

[0029] For the Al-Mg-Sc alloy sheet to be welded, the preferred composition by mass percentage includes 3.5 wt.%~6.0 wt.% Mg, 0.08 wt.%~0.30 wt.% Sc, 0.08 wt.%~0.15 wt.% Zr, 0.05 wt.%~0.5 wt.% Mn, 0 wt.%~0.2 wt.% Cu, 0.01 wt.%~0.4 wt.% Zn, 0 wt.%~0.4 wt.% Fe, 0 wt.%~0.2 wt.% Si, 0 wt.%~0.1 wt.% Cr, and 0 wt.%~0.2 wt.% Ti, with the balance being Al and unavoidable impurity elements. In fact, the welding process parameters provided by this invention can also be applied to other Al-Mg series aluminum alloys. However, the above alloy composition formulation achieves a better balance of material strength, plasticity, corrosion resistance, and weldability. In particular, the optimal selection of Mg and Sc elements can promote a more stable solid solution strengthening effect in the alloy plate, and also more effectively form precipitates. This effectively pins grain boundaries during the welding thermal cycle, inhibits recrystallization and grain coarsening, and ultimately refines the grains of the weld and heat-affected zone more significantly, further improving the toughness and stress corrosion cracking resistance of the resulting welded joint.

[0030] Furthermore, it is preferable that the flow rate of the shielding gas used in gas metal arc welding (GMAW) is 15 L / min to 28 L / min, in order to form a stable shielding gas curtain with good laminar flow. This preferred shielding gas flow rate range can further optimize the tension distribution on the surface of the molten pool, thereby stabilizing the arc morphology, reducing spatter, and making the molten pool surface smoother, ultimately achieving better welding results. In this invention, the shielding gas is exemplarily argon.

[0031] In several typical implementations, for thin plates with a thickness of 1 mm ≤ W ≤ 4 mm, a welding current of 62 A to 81 A and a voltage of 16 ± 1 V are preferred. Based on this preferred current and voltage, the arc energy is more moderate, the molten pool volume is small and shallow, and surface tension dominates the molten pool shape, thereby more effectively preventing burn-through and molten pool collapse, which are common phenomena in thin plate welding. At the same time, within this parameter range, the heat input is more strictly controlled to a level that does not lead to grain coarsening, which is more conducive to retaining the fine precipitates in the Al-Mg-Sc alloy, ultimately resulting in a higher weldability and elongation.

[0032] In several other typical implementations, when 4mm < W ≤ 10mm, it is preferable to use a welding current of 170A~190A and a welding voltage of 23±1V for gas metal arc welding. This parameter range can provide more sufficient and stable penetration, and together with the grain-refining effect of Sc element in Al-Mg-Sc alloy, it can more effectively suppress the softening of the heat-affected zone and obtain a welded joint with higher strength.

[0033] For cases where 4mm < W ≤ 10mm, in order to form a stable molten pool flow, allow the molten metal to fill the bottom of the groove more fully, and provide sufficient space for the molten pool metal to flow and solidify, it is further preferred that the single-sided angle of the V-groove is 15°~30° and the welding assembly gap is 0.5mm~2mm.

[0034] Furthermore, when 4mm < W ≤ 10mm, a two-pass welding sequence is preferred, with the first pass having a welding gap of 0.5mm to 1.0mm and the subsequent two passes each having an independent welding gap of 1.5mm to 2.0mm. In this preferred configuration, the first weld (root pass) uses a smaller gap of 0.5mm to 1.0mm, which effectively controls the heating depth of the arc on the root base material. It also makes it easier for the welder or automatic welding equipment to control the shape of the molten pool, resulting in a more uniform and dense root weld. The subsequent two welds (filler passes) use a larger gap of 1.5mm to 2.0mm, significantly improving welding efficiency and filler metal utilization. This also facilitates the escape of dissolved gases from the molten pool, further reducing porosity defects and improving weld quality. This first-pass, second-pass welding mechanism, combined with the differentiated gap design, ensures that the welded joint maintains high strength while exhibiting superior dimensional stability and consistent mechanical properties. Based on this, it is preferable that the welding speed of the first pass is 0.6±0.05 m / min, and the welding speeds of the latter two passes are each 0.9±0.05 m / min independently. This preferred speed gradient can further optimize the interpass temperature, making the mechanical properties of each region of the joint more uniform, and further improving the overall weldability.

[0035] To avoid ambiguity, in actual welding, the above "first pass, last two passes" actually refers to three passes: the first pass is the first pass for the root pass, and the last two passes refer to the two subsequent passes for filling and covering.

[0036] In several typical embodiments, based on the composition of the aforementioned alloy plate, the welding wire used for gas metal arc welding is preferably an Al-Mg-Sc series welding wire. This Al-Mg-Sc series welding wire, by mass percentage, comprises 5.8 wt.% to 6.8 wt.% Mg, 0.3 wt.% to 0.50 wt.% Sc, 0.08 wt.% to 0.15 wt.% Zr, 0 wt.% to 0.3 wt.% Mn, 0 wt.% to 0.1 wt.% Cu, 0 wt.% to 0.3 wt.% Zn, 0 wt.% to 0.3 wt.% Fe, 0 wt.% to 0.2 wt.% Si, 0 wt.% to 0.3 wt.% Cr, and 0 wt.% to 0.05 wt.% Ti, with the balance being Al and unavoidable impurity elements. Based on this optimized element content ratio, it can be matched with the composition of the alloy plate to be welded, and more effectively achieve the comprehensive effect of uniform weld structure, fine grains, high strength, good elongation and high welding coefficient.

[0037] In practical applications, it is preferred to perform gas metal arc welding (GMAW) under conditions of temperature ≥0℃ (specifically 5℃~35℃) and relative humidity ≤85%RH (specifically 30%RH~60%RH) to effectively reduce the risk of cold cracking, while better maintaining the effective protective effect of the shielding gas, reducing hydrogen intrusion, and further improving the purity of the molten pool metal.

[0038] Furthermore, before performing gas metal arc welding (GMAW), the Al-Mg-Sc alloy sheet is formed by rolling; the welding direction of GMAW is parallel or perpendicular to the rolling extension direction. The rolled sheet exhibits a distinct fibrous structure, with elongated grains along the rolling direction and oriented alloying elements and inclusions. When the welding direction is parallel to the rolling direction, the softened region of the heat-affected zone extends along the rolling direction, and the solidification structure of the weld metal is consistent with the fiber direction of the base metal, which is beneficial for stress transfer and dispersion, improving the tensile strength and fatigue performance of the joint under longitudinal loads. When the welding direction is perpendicular to the rolling direction, the heat-affected zone spans the fiber direction, effectively blocking weak paths at grain boundaries and inhibiting rapid crack propagation along grain boundaries.

[0039] In several preferred embodiments, an Al-Mg-Sc alloy welded joint is formed after gas metal arc welding (GMAW). The Al-Mg-Sc alloy welded joint has a yield strength of 150 MPa to 250 MPa, a tensile strength of 260 MPa to 330 MPa, an elongation of 4% to 12%, and a weld coefficient of 0.75 to 0.95 (more preferably, a yield strength of 190 MPa to 240 MPa, a tensile strength of 280 MPa to 320 MPa, an elongation of 5% to 10%, and a weld coefficient of 0.8 to 0.95). That is to say, the above welding method can effectively restore or maintain most of the strength of the Al-Mg-Sc alloy base material. Simultaneously, the elongation indicates that the resulting joint can absorb a certain amount of energy before fracture, improving its reliability under load. The weld coefficient signifies the effectiveness of the above welding process in controlling heat input and optimizing microstructure.

[0040] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0041] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0042] Example 1

[0043] A gas metal arc welding (MIG) method for Al-Mg-Sc alloy plates:

[0044] The sheet metal welded in this embodiment has a thickness of 1.6 mm and its alloy composition includes Mg 4.5 wt.%, Sc 0.14 wt.%, Zr 0.11 wt.%, Mn 0.21 wt.%, Cu 0.05 wt.%, Zn 0.1 wt.%, Fe 0.06 wt.%, Si 0.05 wt.%, and Cr 0.0005 wt.%. The welding wire used has an alloy composition including Mg 6.1 wt.%, Sc 0.35 wt.%, Zr 0.12 wt.%, Mn 0.15 wt.%, Fe 0.05 wt.%, and Si 0.05 wt.%.

[0045] During welding, the welding direction is along the rolling direction. The temperature of the welding environment is 20℃, and the relative humidity is 41%RH.

[0046] The welding process parameters are: welding current 72A, welding voltage 16.9V, welding speed 0.7m / min, and shielding gas Ar flow rate 16L / min.

[0047] After welding, an Al-Mg-Sc alloy welded joint is formed, which includes a weld zone, a fusion zone, and a heat-affected zone. The grain structure is shown in the figure. Figure 1 and Figure 2 .

[0048] Example 2

[0049] The only difference between this embodiment and Embodiment 1 is that the welding speed in the welding process parameters is changed to 0.4 m / min.

[0050] After welding, an Al-Mg-Sc alloy welded joint is formed, which includes a weld zone, a fusion zone, and a heat-affected zone. The grain structure is shown in the figure. Figure 3 and Figure 4 .

[0051] Example 3

[0052] The only difference between this embodiment and Embodiment 1 is that the welding current in the welding process parameters is changed to 81A.

[0053] Example 4

[0054] The only difference between this embodiment and Embodiment 1 is that the welding current in the welding process parameters is changed to 62A and the welding voltage is changed to 16.1V.

[0055] Example 5

[0056] The only difference between this embodiment and Embodiment 1 is that the flow rate of the shielding gas Ar in the welding process parameters is changed to 25 L / min.

[0057] Example 6

[0058] A MIG welding method for Al-Mg-Sc alloy plates:

[0059] The sheet metal welded in this embodiment has a thickness of 6.8 mm and its alloy composition includes Mg 4.4 wt.%, Sc 0.15 wt.%, Zr 0.12 wt.%, Mn 0.25 wt.%, Cu 0.06 wt.%, Zn 0.12 wt.%, Fe 0.05 wt.%, and Si 0.04 wt.%. The welding wire used has an alloy composition including Mg 6.2 wt.%, Sc 0.36 wt.%, Zr 0.10 wt.%, Mn 0.18 wt.%, Fe 0.06 wt.%, and Si 0.04 wt.%.

[0060] During welding, the welding direction is along the rolling direction. The welding environment temperature is 25℃ and the relative humidity is 38%RH.

[0061] Before welding, the plate is beveled in a V-shape with an angle of 15° on one side.

[0062] The welding process parameters are as follows: welding current 180A, welding voltage 23.2V, shielding gas Ar flow rate 16L / min. The welding passes are 1 in front and 2 behind, with a welding gap of 1mm in front and 2mm behind, and a welding speed of 0.6m / min in front and 0.9m / min behind.

[0063] Example 7

[0064] The only difference between this embodiment and embodiment 6 is that the welding current in the welding process parameters is changed to 170A and the welding voltage is changed to 22.7V.

[0065] Example 8

[0066] The only difference between this embodiment and embodiment 6 is that the welding current in the welding process parameters is changed to 189A and the welding voltage is changed to 23.4V.

[0067] Example 9

[0068] The only difference between this embodiment and Embodiment 1 is that the alloy composition of the sheet to be welded is changed to include Mg 3.0wt.%, Sc 0.05wt.%, Zr 0.16wt.%, Mn 0.02wt.%, Cu 0.3wt.%, Zn 0.002wt.%, and Fe 0.1wt.%.

[0069] Example 10

[0070] The only difference between this embodiment and Embodiment 1 is that the alloy composition of the sheet to be welded is changed to include 6.3 wt.% Mg, 0.35 wt.% Sc, 0.06 wt.% Zr, 0.6 wt.% Mn, 0.5 wt.% Zn, 0.06 wt.% Fe, and 0.3 wt.% Si.

[0071] Example 11

[0072] The only difference between this embodiment and Embodiment 1 is that the alloy composition of the welding wire used for welding is changed to include Mg 5.5wt.%, Sc 0.55wt.%, Zr 0.06wt.%, Mn 0.5wt.%, Cu 0.15wt.%, Zn 0.5wt.%, Fe 0.4wt.%, and Si 0.3wt.%.

[0073] Example 12

[0074] The only difference between this embodiment and Embodiment 1 is that the alloy composition of the welding wire used for welding is changed to include Mg 7.0wt.%, Sc 0.2wt.%, Zr 0.18wt.%, Fe 0.4wt.%, Si 0.3wt.%, Cr 0.4wt.%, and Ti 0.08wt.%.

[0075] Example 13

[0076] The only difference between this embodiment and Embodiment 1 is that the welding parameters are changed to: welding current 100A, welding voltage 20V, welding speed 0.4m / min, and shielding gas Ar flow rate 28L / min.

[0077] Example 14

[0078] The only difference between this embodiment and embodiment 6 is that the welding current in the welding process parameters is changed to 160A and the welding voltage is changed to 21V.

[0079] Example 15

[0080] The only difference between this embodiment and embodiment 6 is that the welding current in the welding process parameters is changed to 200A and the welding voltage is changed to 25V.

[0081] Comparative Example 1

[0082] The difference between this comparative example and Example 1 is that the welding current in the welding process parameters is changed to 105A.

[0083] After welding, the grain structure of the resulting weld joint is shown in the figure. Figure 5 .

[0084] Comparative Example 2

[0085] The difference between this comparative example and Example 1 is that the welding speed in the welding process parameters is changed to 1.0 m / min.

[0086] Comparative Example 3

[0087] The difference between this comparative example and Example 6 is that the board material was not beveled.

[0088] Comparative Example 4

[0089] The difference between this comparative example and Example 1 is that the welding voltage in the welding process parameters is changed to 10V.

[0090] Comparative Example 5

[0091] The difference between this comparative example and Example 6 is that the welding current in the welding process parameters is changed to 220A.

[0092] Comparative Example 6

[0093] The difference between this comparative example and Example 6 is that the welding speed in the welding process parameters is changed to 0.4 m / min.

[0094] Comparative Example 7

[0095] The difference between this comparative example and Example 6 is that the welding voltage in the welding process parameters is changed to 20V.

[0096] Comparative Example 8

[0097] The difference between this comparative example and Example 6 is that the welding voltage in the welding process parameters is changed to 28V.

[0098] Test methods

[0099] Tensile strength, yield strength, and elongation: tested according to GB / T 16865-2023. Welding coefficient = joint strength / base material strength, where "strength" refers to tensile strength.

[0100] The above tests were performed on the welded joints of the Al-Mg-Sc alloy plates obtained in each embodiment and comparative example, and the results are shown in Table 1.

[0101] Table 1

[0102]

[0103] As can be seen from the above description, the above embodiments of the present invention are based on MIG welding. By limiting the welding parameters for the thin plate range of 1mm≤W≤4mm and the medium-thick plate range of 4mm<W≤10mm respectively, the purpose of effectively avoiding burn-through defects in thin plates and non-fusion defects in medium-thick plates is achieved, while optimizing the weld formation quality. Thus, high-quality welded joints with high tensile strength, high elongation and high welding coefficient can be obtained under different thickness specifications.

[0104] Specifically, in each embodiment:

[0105] Comparing Examples 9 and 10 with Example 1, it can be seen that by further optimizing the alloy composition of the sheet to be welded, a better balance can be achieved in terms of material strength, plasticity, corrosion resistance and weldability.

[0106] Comparing Examples 11 and 12 with Example 1, it can be seen that by further optimizing the alloy composition of the welding wire, it is possible to match the composition of the alloy plate to be welded, and more effectively achieve the comprehensive effect of uniform weld structure, fine grains, high strength, good elongation and high welding coefficient.

[0107] Comparing Example 13 with Example 1, it can be seen that for plates with a thickness of 1mm≤W≤4mm, by further optimizing the welding parameters, it is possible to more effectively prevent burn-through and molten pool collapse, which are common phenomena in thin plate welding; at the same time, it is also more conducive to retaining the fine precipitates in the Al-Mg-Sc alloy, and ultimately obtaining a higher welding coefficient and elongation.

[0108] Comparing Examples 14 and 15 with Example 6, it can be seen that for plates with a thickness of 4mm < W ≤ 10mm, by further optimizing the welding parameters, a more sufficient and stable penetration capability can be provided. At the same time, in conjunction with the grain-refining effect of Sc element in Al-Mg-Sc alloy, the softening of the heat-affected zone can be more effectively suppressed, resulting in a welded joint with higher strength.

[0109] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0110] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A welding method for Al-Mg-Sc alloy plates, characterized in that, The Al-Mg-Sc alloy plate was subjected to gas metal arc welding using a flat butt joint method; the thickness of the Al-Mg-Sc alloy plate was denoted as W, where 1mm ≤ W ≤ 10mm; When 1mm≤W≤4mm, the welding current used in the gas metal arc welding is 62A~100A, the welding voltage is 15V~20V, and the welding speed is 0.4m / min~0.8m / min. When 4mm < W ≤ 10mm, a symmetrical V-groove is processed on the welding interface of the Al-Mg-Sc alloy plate, and the welding current used for the gas metal arc welding is 160A~200A, the welding voltage is 21V~25V, and the welding speed is 0.5m / min~1.0m / min.

2. The welding method for Al-Mg-Sc alloy plates according to claim 1, characterized in that, By mass percentage, the Al-Mg-Sc alloy sheet comprises 3.5wt.%~6.0wt.% Mg, 0.08wt.%~0.30wt.% Sc, 0.08wt.%~0.15wt.% Zr, 0.05wt.%~0.5wt.% Mn, 0wt.%~0.2wt.% Cu, 0.01wt.%~0.4wt.% Zn, 0wt.%~0.4wt.% Fe, 0wt.%~0.2wt.% Si, 0wt.%~0.1wt.% Cr, and 0wt.%~0.2wt.% Ti, with the balance being Al and unavoidable impurity elements.

3. The welding method for Al-Mg-Sc alloy plates according to claim 1, characterized in that, The flow rate of the shielding gas used in the gas metal arc welding is 15L / min to 28L / min.

4. The welding method for Al-Mg-Sc alloy plates according to any one of claims 1 to 3, characterized in that, When 1mm≤W≤4mm, the welding current used in the gas metal arc welding is 62A~81A and the welding voltage is 16±1V. When 4mm < W ≤ 10mm, the welding current used in the gas metal arc welding is 170A~190A and the welding voltage is 23±1V.

5. The welding method for Al-Mg-Sc alloy plates according to any one of claims 1 to 3, characterized in that, When 4mm < W ≤ 10mm, the single-sided angle of the V-groove is 15°~30°, and the welding assembly gap is 0.5mm~2mm.

6. The welding method for Al-Mg-Sc alloy plates according to claim 5, characterized in that, When 4mm < W ≤ 10mm, the welding sequence is one pass followed by two passes, with the welding gap of the first pass being 0.5mm to 1.0mm and the welding gap of the last two passes being 1.5mm to 2.0mm each.

7. The welding method for Al-Mg-Sc alloy plates according to any one of claims 1 to 3, characterized in that, The welding wire used in the gas metal arc welding (GMAW) is an Al-Mg-Sc series welding wire, and by mass percentage, the Al-Mg-Sc series welding wire includes 5.8wt.%~6.8wt.% Mg, 0.3wt.%~0.50wt.% Sc, 0.08wt.%~0.15wt.% Zr, 0wt.%~0.3wt.% Mn, 0wt.%~0.1wt.% Cu, 0wt.%~0.3wt.% Zn, 0wt.%~0.3wt.% Fe, 0wt.%~0.2wt.% Si, 0wt.%~0.3wt.% Cr, and 0wt.%~0.05wt.% Ti, with the balance being Al and unavoidable impurity elements.

8. The welding method for Al-Mg-Sc alloy plates according to any one of claims 1 to 3, characterized in that, The gas metal arc welding is performed under conditions of temperature ≥0℃ and relative humidity ≤85%RH.

9. The welding method for Al-Mg-Sc alloy plates according to any one of claims 1 to 3, characterized in that, Before performing the gas metal arc welding (GMAW), the Al-Mg-Sc alloy sheet is formed by rolling; the welding direction of the GMAW is parallel or perpendicular to the rolling extension direction.

10. The welding method for Al-Mg-Sc alloy plates according to any one of claims 1 to 3, characterized in that, After the gas metal arc welding (GMAW) is performed, an Al-Mg-Sc alloy welded joint is formed. The yield strength of the Al-Mg-Sc alloy welded joint is 150MPa~250MPa, the tensile strength is 260MPa~330MPa, the elongation is 4%~12%, and the welding coefficient is 0.75~0.95.

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