A welding wire for welding AlSi10MnMg pressure casting aluminum alloy and Al-Mg-Si extruded aluminum alloy, a preparation method and application thereof

Abstract

This invention relates to the field of aluminum alloy welding technology, specifically to a welding wire, its preparation method, and its application for welding AlSi10MnMg die-cast aluminum alloy and Al-Mg-Si extruded aluminum alloy. By adding alloy metals La, Sr, and Y to the composition of traditional welding wires and precisely controlling the content of Sr, La, and Y, the welding performance of the welding wire can be significantly improved. Applying this invention to the welding of the frame of aluminum alloy battery trays improves the microstructure, suppresses the formation of porosity and looseness within the metal, and ultimately improves the welding reliability of dissimilar alloy components of power battery trays. It also significantly improves the mechanical properties of the welding wire material and eliminates microcracks and porosity defects at the weld seam after welding.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy welding technology, specifically to a welding wire for welding AlSi10MnMg die-cast aluminum alloy and Al-Mg-Si extruded aluminum alloy, its preparation method, and its application. Background Technology

[0002] With the rapid development of electrification in the transportation sector, battery trays and other assemblies in new energy vehicles, as crucial load-bearing components, have always had key performance indicators such as robustness, reliability, and sealing to strive for by manufacturers. Battery trays and similar components are made entirely of aluminum alloy, and the aluminum alloy parts require welding for fixation at connection points. The quality of the welding determines the relevant properties of the materials. During the welding process, brittle intermetallic compounds are easily formed at the interface, significantly reducing the strength and reliability of the weld. Poor welding quality often leads to cracking at the weld seam, further reducing the weld's strength and reliability. Therefore, the welding quality at the weld position determines the product's critical performance.

[0003] In the welding and fusion process of aluminum alloys, aluminum alloy welding wire is needed as the connecting material after melting. Al-Si aluminum alloy welding wire has advantages such as low melting point, wide crystallization temperature range, good fluidity after melting, and low solidification shrinkage, and is widely used in various technical fields. However, the application of commercially available Al-Si aluminum alloy welding wire in the welding of aluminum alloy battery tray components still has shortcomings. Battery trays are often made by welding components with different alloy compositions. The most common is the welding between AlSi10MnMg die-cast aluminum alloy and Al-Mg-Si extruded aluminum alloy. Welding these two dissimilar aluminum alloy components will have the following defects: 1. Porosity defects: The casting itself contains micro-shrinkage or residual gas during the casting process. The welding heat will cause these residual gases to expand and enter the weld pool. The high Si content of the welding wire melt solidifies and develops dendrites, which hinders the gas from rising and escaping, thus producing porosity and pores at the weld, reducing the mechanical strength of the weld. 2. Weld hot cracking: Extruded profiles contain Mg and Si, while castings contain a high Si content. When the weld pool solidifies, the two materials mix and easily form low-melting-point eutectics at the grain boundaries, such as Mg2Si. When the aluminum grains have solidified, the low-melting-point eutectics are still in a liquid state. As the temperature gradually decreases, the metal shrinks. When the shrinkage stress exceeds the yield point of the eutectic, microcracks will occur. As cooling progresses, the microcracks develop into macroscopic hot cracks.

[0004] Due to the aforementioned internal defects in the metal, cracks often occur at the weld seams of the product. Therefore, the assembly and welding of aluminum alloy power battery trays is a difficult point that production personnel have always needed to improve and solve. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a welding wire for welding AlSi10MnMg die-cast aluminum alloy and Al-Mg-Si extruded aluminum alloy, along with its preparation method and application. By adding alloying elements to control the microstructure and properties of the welding wire alloy, the mechanical properties of the welding wire material are significantly improved, the microstructure is enhanced, and the generation of porosity and looseness within the metal is reduced. Ultimately, this improves the welding reliability of dissimilar alloy components in power battery trays and reduces microcracks and porosity defects at the weld seam after welding.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A special welding wire for dissimilar aluminum alloys for new energy vehicle battery trays, the alloy composition of which is designed as follows: alloy element weight percentage Si: 4.5~6.0%, Fe: ≤0.8%, Cu: ≤0.3%, Mn: ≤0.05%, Mg: ≤0.05%, Zn: ≤0.1%, Ti: ≤0.2%, Sr: 0.05~0.14%, La: 0.07~0.5%, Y: 0.05~0.25%; balance Al.

[0007] In the alloy composition, the weight percentage of alloying elements is: 5×Sr≤La+Y.

[0008] The alloy composition contains the following alloying elements by weight percentage: 0.7% ≥ La + Y ≥ 0.4%. Insufficient La and Y content cannot fully refine the grains, while excessive La and Y content will form coarse enriched phases. These phases are brittle and will become crack initiation sites, leading to decreased mechanical properties and deterioration of welding performance.

[0009] The preparation method includes the following steps: (1) Composition design: Alloy element weight percentages: Si: 4.5~6.0%, Fe: ≤0.8%, Cu: ≤0.3%, Mn: ≤0.05%, Mg: ≤0.05%, Zn: ≤0.1%, Ti: ≤0.2%, Sr: 0.05~0.14%, La: 0.07~0.5%, Y: 0.05~0.25%; balance Al; (2) Feeding: Feeding is carried out in batches. First, feed the intermediate alloy containing Si and aluminum ingots, then feed the intermediate alloy containing Mn, Cu and Ti into the molten alloy, and finally feed the intermediate alloy containing Mg, La, Sr and Y into the settling furnace. (3) Degassing and slag removal: The volume ratio of chlorine-argon mixed gas is 1:4 to 2:3, and the gas flow rate is 12 to 20 m³ / h. Degassing and slag removal are carried out online in the flow channel. (4) Casting: Hot top semi-continuous casting is adopted, with a casting temperature of 690-720℃ and a water flow rate of 120-180m³ / h to obtain a cast rod with a diameter of 120-180mm; (5) Heat equalization: Keep warm at 550-580℃ for 8-20 hours; first cool in the furnace to 200-300℃ and then air cool; (6) Sawing the car body: After homogenization, cut off the head and tail of the ingot with a length of more than 30mm, and machine off the surface segregation layer of more than 5mm; (7) Hot extrusion: Die temperature control: 440~490℃, ingot preheating temperature: 490~540℃, ingot gradient heating, extrusion cylinder temperature control: 430~450℃, extrusion speed control: 2~3m / min, to obtain a continuous extruded billet with a diameter of 10~15mm; extrusion temperature control: 520~540℃; (8) Rewinding: The continuously extruded billet is rewound at the end of the extrusion production line using a reel; (9) Continuous extrusion and drawing: After the surface of the continuously extruded billet is cleaned, it is fed into a continuous extrusion press for extrusion molding. The billet is then drawn into an aluminum alloy welding wire product with a diameter of 0.8 to 2.4 mm. The welding wire product is ultrasonically cleaned, dried and wound up to obtain the aluminum alloy welding wire.

[0010] In step (9), the surface cleaning of the continuously extruded billet includes four steps: surface brushing with a rotating wire brush, alkaline washing with 8-15% NaOH by mass, acid washing with 8-13% sulfuric acid by mass, and high-pressure rinsing with clean water at 40-60℃.

[0011] In step (3), the hydrogen content after degassing is controlled to be below 0.1 mL / 100 g Al.

[0012] Application of special welding wire for dissimilar aluminum alloy welding structures in welding structural components of aluminum alloy battery trays for new energy vehicles.

[0013] The base alloy composition of the aluminum alloy battery tray components welded together is Al-Mg-Si and AlSi10MnMg.

[0014] Advantages of the invention: 1. This invention significantly improves the welding performance of traditional welding wire by adding alloying elements Sr, La, and Y to the composition and precisely controlling their content. The principle is as follows: Sr can refine the grain size of the welding wire metal, change the morphology of eutectic silicon, transform needle-like / lamellar silicon into fine fibrous or granular silicon, reduce the spacing between secondary dendrite arms, suppress primary silicon, and significantly improve the strength, plasticity, and toughness of the weld. Adding Sr alone may increase the hydrogen content and porosity of the welding wire to some extent; however, when combined with an appropriate amount of La, due to its strong chemical reactivity, low-density La2O3 is generated, which carries impurities and hydrogen from the melt to the surface, thus offsetting the adverse effects of Sr on hydrogen content and porosity, ensuring joint tightness; at the same time, La can also accumulate at the solid-liquid interface front, producing compositional supercooling, hindering grain growth, and significantly refining the α-Al matrix grains of the weld metal. The effects of adding an appropriate amount of Y on the weld melt are as follows: Y, also possessing high chemical reactivity, preferentially reacts with O, H, S, and low-melting-point impurities to form high-melting-point compounds, which float to the surface and are removed or form fine, dispersed inclusions, reducing porosity and oxide inclusions, further enhancing the purification effect of La. Secondly, Y adsorbs at the α-Al crystal nucleus growth interface, inhibiting columnar crystal growth and promoting equiaxed crystal formation, resulting in grain refinement of approximately 50%. It also modifies the eutectic Si phase, transforming it from coarse needle-like flakes to fine granular / fibrous structures, significantly improving the joint's strength, toughness, and plasticity, while simultaneously reducing the surface tension of the molten pool, improving fluidity, and enhancing weld formation and density. Thirdly, it refines the microstructure and optimizes phase morphology, disperses solidification stress, and widens the effective feeding range between the solid and liquid phases; the columnar crystal region narrows, and the number of equiaxed crystals increases, reducing the continuous network distribution of low-melting-point phases between grains, thereby reducing hot cracking sensitivity and the risk of hot cracking. Fourth, trace amounts of Y solid solution or form dispersed precipitates produce solid solution strengthening and second phase strengthening; at the same time, it purifies grain boundaries, improves phase interface bonding, enhances the high-temperature stability, corrosion resistance and fatigue performance of the weld, delays joint failure, realizes microalloying strengthening, and improves the fatigue resistance of the metal.

[0015] 2. The welding wire of this invention was applied to the frame welding of aluminum alloy battery tray structural components in new energy vehicles, and to the welding of components with different alloy grades. Good results were achieved, which are reflected in the improvement of welding processability: optimizing the fluidity of the molten pool, reducing spatter and slag inclusions, reducing the tendency of hot cracking; improving arc stability; improving post-weld formation, reducing porosity and hydrogen content, and ensuring joint tightness. Attached Figure Description

[0016] Figure 1 These are comparative photographs of the mechanical specimens in Example 3 before and after tensioning. Figure 2 These are macroscopic low-magnification photographs of the weld section specimens from Example 4; in which... Figure 2 A is a low-magnification photograph of cross-section specimen A; Figure 2B is a low-magnification photograph of cross-sectional specimen B; Figure 2 C is a low-magnification photograph of cross-section specimen C; Figure 2 D is a low-magnification photograph of cross-section specimen D; Figure 2 E is a low-magnification photograph of cross-sectional specimen E; Figure 3 These are microscopic photographs of the metallographic specimens of the finished welding wire in Example 5; whereby... Figure 3 A is a photograph of the microscopic metallographic sample A; Figure 3 B is a photograph of the microscopic metallographic sample B; Figure 3 C is a photograph of the microscopic metallographic sample C; Figure 3 D is a photograph of the microscopic metallographic sample D; Figure 3 E is a photograph of the microscopic metallographic sample E. Detailed Implementation

[0017] Example 1

[0018] A welding wire for welding AlSi10MnMg die-cast aluminum alloy and Al-Mg-Si extruded aluminum alloy, its preparation method, and its application. The preparation method includes the following steps: (1) Composition design: Five alloy compositions of welding wire A, welding wire B, welding wire C, welding wire D and welding wire E were designed and verified respectively; (2) Feeding: Feeding is carried out in batches. First, feed the intermediate alloy containing Si and aluminum ingots, then feed the intermediate alloy containing Mn, Cu and Ti into the molten alloy, and finally feed the intermediate alloy containing Mg, La, Sr and Y into the settling furnace. (3) Degassing and slag removal: A chlorine-argon mixed gas with a volume ratio of 1:4 and a gas flow rate of 20 m³ / h is used for online degassing and slag removal in the flow channel; (4) Casting: Hot top semi-continuous casting is adopted, the casting temperature is 700℃, the water flow rate is 120m³ / h, and a casting rod with a diameter of 120mm is obtained. (5) Heat equalization: 550℃ / 10h; first furnace cooling to 250℃ and then air cooling to room temperature; (6) Sawing the car body: After homogenization, cut off the head and tail of the ingot with a length of more than 30mm, and machine off the surface segregation layer of more than 5mm; (7) Hot extrusion: Die temperature control: 450℃, ingot preheating temperature: 510~460℃, ingot gradient heating, extrusion cylinder temperature control: 430℃, extrusion speed control: 3m / min, to obtain a continuous extruded billet with a diameter of 15mm; (8) Rewinding: The continuously extruded billet is rewound at the end of the extrusion production line using a reel; (9) Continuous extrusion: After surface cleaning, the continuous extrusion billet is fed into a continuous extrusion press for extrusion molding. After four drawing passes, an aluminum alloy welding wire with a diameter of 1.6 mm is obtained. The welding wire is ultrasonically cleaned, dried and wound up to obtain the aluminum alloy welding wire.

[0019] In step (9), the continuous extrusion billet surface cleaning includes four steps: surface brushing with a rotating wire brush, alkaline washing with 10% NaOH by mass, acid washing with 10% sulfuric acid by mass, and high-pressure rinsing with 50°C clean water.

[0020] In step (3), the hydrogen content after degassing is controlled to be below 0.1 mL / 100gAl.

[0021] Verification was conducted using five alloy compositions (based on the weight percentage of alloying elements, with the balance being Al): The alloy composition of welding wire A is: (excluding Sr, La, and Y elements) Si: 4.538%, Fe: 0.124%, Cu: 0.021%, Mn: 0.011%, Mg: 0.011%, Zn: 0.009%, Ti: 0.026%, the remainder being Al; The alloy composition of welding wire B is: (satisfying the relationship 5×Sr≤La+Y, 0.7%≥La+Y≥0.4%) Si: 4.559%, Fe: 0.180%, Cu: 0.029%, Mn: 0.014%, Mg: 0.007%, Zn: 0.011%, Ti: 0.025%, Sr: 0.063%, La: 0.322%, Y: 0.115%, the remainder being Al; The alloy composition of welding wire C is: (satisfying 5×Sr≤La+Y, but not satisfying the relationship 0.7%≥La+Y≥0.4%) Si: 4.665%, Fe: 0.153%, Cu: 0.029%, Mn: 0.008%, Mg: 0.014%, Zn: 0.005%, Ti: 0.047%, Sr: 0.054%, La: 0.678%, Y: 0.094%, with the remainder being Al; The alloy composition of welding wire D is: (does not satisfy 5×Sr≤La+Y, but satisfies the relationship 0.7%≥La+Y≥0.4%) Si: 4.744%, Fe: 0.158%, Cu: 0.037%, Mn: 0.010%, Mg: 0.012%, Zn: 0.007%, Ti: 0.040%, Sr: 0.128%, La: 0.350%, Y: 0.086%, with the remainder being Al; The alloy composition of welding wire E is: (satisfying 5×Sr≤La+Y, but not satisfying the relationship 0.7%≥La+Y≥0.4%) Si: 4.917%, Fe: 0.099%, Cu: 0.084%, Mn: 0.017%, Mg: 0.013%, Zn: 0.008%, Ti: 0.032%, Sr: 0.021%, La: 0.171%, Y: 0.047%, with the remainder being Al.

[0022]

[0023] Example 2 Sample preparation and material mechanical testing After the welding wire manufacturing is completed, the finished welding wire undergoes mechanical testing in accordance with the national standard GB / T 228.1-2021. Experimental equipment and materials: Testing machine: Electronic universal testing machine, accuracy class 1; Extensometer: Contact extensometer, used to accurately measure deformation during the yielding stage; Measuring tool: Vernier calipers with a resolution of 0.01 mm; Samples: Welding wire samples were prepared by directly cutting them from the spools of welding wires A to E respectively.

[0024] Sample preparation: Sampling: Randomly cut a straight piece of welding wire with a length of approximately 350mm. Avoid bending, twisting or damaging the surface of the welding wire during the sampling process. Pretreatment: Clean the surface of the welding wire with anhydrous ethanol and degreased cotton to remove any oil and coatings that may be present; Marking: On the parallel section in the middle of the welding wire, lightly mark the original gauge length L0=100 mm with a scribing tool; Clamping end treatment: To prevent the sample from slipping or breaking prematurely at the clamping point, use special clamps to clamp the sample at both ends (approximately 50 mm in length).

[0025] The test results are shown in Table 2:

[0026] Example 3 Butt welding tensile failure test After the five types of welding wire are produced, as shown in the attached document. Figure 1As shown, welding wires A through E were used to perform center-to-center butt welding on a 1 / 2 extruded profile planar mechanical sample Al-Mg-Si (T6) and a 1 / 2 die-cast planar mechanical sample AlSi10MnMg. Before welding, the weld seam of the base material was cleaned. After edge butt welding, MIG flat welding was used with pure argon at a flow rate of 12–18 L / min. The 1.2 mm welding wire current was 100–180 A, the voltage was 18–25 V, and the welding speed was 0.3–0.7 m / min. The wire feed speed was matched with the welding speed to ensure sufficient deposition. Five mechanical specimens were obtained: mechanical specimen A, mechanical specimen B, mechanical specimen C, mechanical specimen D, and mechanical specimen E. Three parallel tests were performed on each type of mechanical specimen.

[0027] The composition of the base material Al-Mg-Si is as follows: Si: 0.512%, Fe: 0.365%, Cu: 0.164%, Mn: 0.010%, Mg: 1.036%, Zn: 0.011%, Cr: 0.139%, Ti: 0.108%, with the remainder being Al; the tensile strength is 290 MPa.

[0028] The composition of the base material AlSi10MnMg is: Si: 9.224%, Fe: 0.299%, Cu: 0.035%, Mn: 0.070%, Mg: 0.264%, Zn: 0.053%, Ti: 0.114%, with the remainder being Al; the tensile strength is 220 MPa. The test results are shown in Table 3.

[0029] Example 4 Porosity detection and low-magnification observation experiments of weld cross-section specimens Five types of welding wires, A through E, were applied to the actual welding of the AlSi10MnMg die-cast beam and Al-Mg-Si extruded frame of the power battery tray. Before welding, the oxide scale on both sides of the weld bevel of the die-cast beam and extruded frame was ground until the metallic luster was exposed. The assembly gap was minimized to prevent the pores of the die-casting from entering from the back. The welding wire and arc were biased towards the Al-Mg-Si extruded frame side (2 / 3 to 4 / 5 of the molten pool area) to prevent the die-casting from overheating and cracking. The front weld was fully filled to form a raised weld, reducing the generation of surface porosity. The welding process was continuous to reduce the number of joints. The weld penetration depth was 0.4–0.6T. Five weld samples were obtained after welding. The weld was cut in the middle to obtain cross-sectional samples. The five types of welding wires A through E corresponded to cross-sectional samples A, B, C, D, and E, respectively. Porosity testing and low-magnification observation experiments were performed on cross-sectional samples A through E.

[0030] (1) Porosity test of weld cross-section specimens: After grinding, polishing, and etching, cross-sectional samples A to E were observed under a microscope. The porosity was assessed by comparing the results with Appendix A of GB / T 22087-2008 "Guideline for Defect Quality Classification of Arc Welded Joints of Aluminum and Aluminum Alloys". The porosity P was calculated using the formula: P = A1 / A2; where A1 is the pore area and A2 is the weld area.

[0031] The results of the porosity test are shown in Table 4:

[0032] (2) Low-magnification comparison of weld section specimens: The low-magnification photographs of the five cross-sectional samples were observed and compared, as shown in the attached figure. Figure 2 As shown, attached Figure 2 Section sample B in section B exhibits the best weld quality, with virtually no noticeable porosity or looseness; attached Figure 2 A. Appendix Figure 2 C. Appendix Figure 2 In Figure E, cross-sections A, C, and E all exhibit varying degrees of porosity; (Attached) Figure 2 The cross-sectional sample D in D has many pores. This is because the content of Sr is relatively high, while the content of La and Y, which can remove impurities and gas, is relatively insufficient, resulting in the inability to remove and clean hydrogen gas in the melt.

[0033] Example 5 Microscopic metallographic structure characteristics observation experiment The longitudinal sections of the five types of welding wire finished products A to E, cut along their length, were coarsely ground with 800# sandpaper, ground to 2000#, and then polished and etched to obtain micro-metallographic specimens A, B, C, D, and E, respectively. The micro-metallographic structure characteristics were observed under a Zeiss metallographic optical microscope.

[0034] As attached Figure 3 As shown, under high magnification, it can be seen that the attached Figure 3 B to Appendix Figure 3 As shown in E, the microstructure of metallographic samples B to E exhibits varying degrees of refinement of the Si phase due to the addition of Sr, La, and Y elements. The Si phase distribution within the microstructure is significantly more uniform and finer. (See attached image.) Figure 3 As shown in sample A, the Si phase in the microstructure is coarse and obvious. The coarse eutectic Si phase is equivalent to a natural crack source and stress concentration point, resulting in brittle fracture and poor welding quality.

Claims

1. A welding wire for welding AlSi10MnMg die-cast aluminum alloy to Al-Mg-Si extruded aluminum alloy, characterized in that, The alloy composition of the welding wire is designed as follows: alloy element weight percentage Si: 4.5~6.0%, Fe: ≤0.8%, Cu: ≤0.3%, Mn: ≤0.05%, Mg: ≤0.05%, Zn: ≤0.1%, Ti: ≤0.2%, Sr: 0.05~0.14%, La: 0.07~0.5%, Y: 0.05~0.25%; balance Al.

2. The welding wire for welding AlSi10MnMg die-cast aluminum alloy and Al-Mg-Si extruded aluminum alloy according to claim 1, characterized in that, In the alloy composition, the weight percentage of alloying elements is: 5×Sr≤La+Y.

3. The welding wire for welding AlSi10MnMg die-cast aluminum alloy and Al-Mg-Si extruded aluminum alloy according to claim 1, characterized in that, The alloy composition contains the following alloying elements by weight percentage: 0.7% ≥ La + Y ≥ 0.4%.

4. A method for preparing the welding wire as described in claim 1, characterized in that, Includes the following steps: (1) Composition design: Alloy element weight percentages: Si: 4.5~6.0%, Fe: ≤0.8%, Cu: ≤0.3%, Mn: ≤0.05%, Mg: ≤0.05%, Zn: ≤0.1%, Ti: ≤0.2%, Sr: 0.05~0.14%, La: 0.07~0.5%, Y: 0.05~0.25%; balance Al; (2) Feeding: Feeding is carried out in batches. First, feed the intermediate alloy containing Si and aluminum ingots, then feed the intermediate alloy containing Mn, Cu and Ti into the molten alloy, and finally feed the intermediate alloy containing Mg, La, Sr and Y into the settling furnace. (3) Degassing and slag removal: The volume ratio of chlorine-argon mixed gas is 1:4 to 2:3, and the gas flow rate is 12 to 20 m³ / h. Degassing and slag removal are carried out online in the flow channel. (4) Casting: Hot top semi-continuous casting is adopted, with a casting temperature of 690-720℃ and a water flow rate of 120-180m³ / h to obtain a cast rod with a diameter of 120-180mm; (5) Heat equalization: Keep warm at 550-580℃ for 8-20 hours; first furnace cool to 200-300℃ and then air cool to room temperature; (6) Sawing the car body: After homogenization, cut off the head and tail of the ingot with a length of more than 30mm, and machine off the surface segregation layer of more than 5mm; (7) Hot extrusion: Die temperature control: 450~490℃, ingot preheating temperature: 490~520℃, ingot gradient heating, extrusion cylinder temperature control: 430~450℃, extrusion speed control: 2~3m / min, to obtain a continuous extruded billet with a diameter of 10~15mm; extrusion temperature control: 520~540℃; (8) Rewinding: The continuously extruded billet is rewound at the end of the extrusion production line using a reel; (9) Continuous extrusion and drawing: After the surface of the continuously extruded billet is cleaned, it is fed into a continuous extrusion press for extrusion molding. The billet is then drawn into an aluminum alloy welding wire product with a diameter of 0.8 to 2.4 mm. The welding wire product is ultrasonically cleaned, dried and wound up to obtain the aluminum alloy welding wire.

5. The method for preparing the welding wire according to claim 4, characterized in that, In step (9), the continuous extrusion billet surface cleaning includes four steps in sequence: surface brushing with a rotating wire brush, alkaline washing with 8-15% NaOH by mass, acid washing with 8-13% sulfuric acid by mass, and high-pressure rinsing with clean water at 40-60℃.

6. The method for preparing the welding wire according to claim 4, characterized in that, In step (3), the hydrogen content after degassing is controlled to be below 0.1 mL / 100 g Al.

7. The application of the welding wire as described in claim 1 in the welding of aluminum alloy battery tray structural components for new energy vehicles.

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