Aluminum alloy soldering lug for improving welding seam quality of dissimilar aluminum alloy as well as preparation method and application of aluminum alloy soldering lug

Abstract

The invention provides an aluminum alloy soldering lug for improving dissimilar aluminum alloy welding seam quality and a preparation method and application of the aluminum alloy soldering lug, and relates to the technical field of metal material welding. The aluminum alloy comprises the following components in percentage by weight: 4.5%-5% of Si, 3.0%-3.5% of Mg, 2%-2.2% of Mn, 0.4%-0.8% of Cr, 2.2%-2.6% of Fe, 0.2%-0.4% of Cu and the balance of Al and inevitable trace elements. According to the aluminum alloy soldering lug provided by the invention, tiny pores and defects in a welding seam can be better filled in the melting process, air holes, inclusions and the like are reduced, and the compactness of the welding seam is improved, so that the sealing property and the corrosion resistance of the welding seam are enhanced. Alloy elements in the soldering lug can be mutually diffused and fused with weldment metal to form a weld joint structure with certain strength and toughness, so that the mechanical property of a welded joint is closer to or better than that of a weldment.

Description

Technical Field

[0001] The present application relates to the technical field of metal material welding, and in particular to an aluminum alloy welding sheet for improving the quality of welds of dissimilar aluminum alloys, and a preparation method and application thereof. Background Art

[0002] Aluminum alloys are widely used in a wide range of fields, including aerospace, automotive, and rail transportation, due to their low density, high specific strength, excellent corrosion resistance, and ease of processing and forming. However, welding aluminum alloys, particularly dissimilar aluminum alloys, presents numerous challenges. The chemical composition and physical properties of different aluminum alloys vary significantly, making welding prone to defects such as cracks and pores, which can affect the quality and performance of welded joints.

[0003] Therefore, designing a welding sheet composition suitable for welding dissimilar aluminum alloys is of great significance to improving the quality and performance of welded joints. Summary of the Invention

[0004] In order to improve the problem of poor joint quality and performance when welding dissimilar aluminum alloys, the present application provides an aluminum alloy welding sheet for improving the quality of welds of dissimilar aluminum alloys, and a preparation method and application thereof.

[0005] In a first aspect, the present application provides an aluminum alloy welding sheet for improving the weld quality of dissimilar aluminum alloys, using the following technical solutions: An aluminum alloy welding sheet for improving the weld quality of dissimilar aluminum alloys comprises the following components by weight: Si 4.5%-5%, Mg 3.0%-3.5%, Mn 2%-2.2%, Cr 0.4%-0.8%, Fe 2.2%-2.6%, Cu 0.2%-0.4%, and the balance being Al and inevitable trace elements.

[0006] The aluminum alloy welding sheet provided by the present invention can improve the quality and performance of welds between dissimilar aluminum alloys. Specifically, silicon, as a deoxidizing element, prevents iron from combining with oxygen and reduces FeO in the molten pool. Silicon has a strong solid solution strengthening effect, effectively improving the strength of the weld. Manganese, as a deoxidizer and alloying agent, combines with sulfur to form manganese sulfide, which desulfurizes the weld, thereby reducing the tendency of hot cracking caused by sulfur. Manganese also increases the strength of the weld and improves the overall strength of the welded joint. Copper, as a conductive element, improves the electrical conductivity of the welding sheet. Chromium increases the hardness and wear resistance of the welding sheet, enhancing the mechanical properties of the welded joint. Chromium also helps improve the corrosion resistance of the welding sheet, enabling it to maintain stable performance in harsh environments. In addition, chromium forms specific phases in the weld and fusion zone, such as α-Al(Fe,Mn,Cr)Si. The formation of these phases has a significant impact on the performance of the weld. An appropriate and evenly distributed α-Al(Fe,Mn,Cr)Si phase can strengthen the aluminum alloy welded joint, improving its tensile strength and yield strength.

[0007] In a second aspect, the present application provides a method for preparing an aluminum alloy welding sheet for improving the quality of welds of dissimilar aluminum alloys, using the following technical solutions: A method for preparing an aluminum alloy welding sheet with improved weld quality comprises the following specific steps: Step S1: melting pure aluminum, pure magnesium, Al-Si master alloy, Al-Fe master alloy, Al-Cu master alloy and Al-Mn master alloy and continuously stirring; Step S2: After slag removal, Al-Cr master alloy is added and smelting is continued; Step S3: refining and degassing the melt smelted in step S2; Step S4: Casting the material obtained in step S3 to obtain a welding blank; Step S5: rolling the welding sheet blank; Step S6: Finally, the surface is cleaned, polished and treated with an anti-oxidation coating.

[0008] Optionally, the smelting temperature in step S1 is 820-840°C.

[0009] Optionally, the rolling temperature in step S5 is 400°C to 500°C.

[0010] Optionally, step S5 further includes an annealing treatment after the rolling process.

[0011] Optionally, the annealing treatment is performed at a temperature of 400-450° C. and for a time of 2-3 hours.

[0012] In a third aspect, the present application provides an aluminum alloy welding sheet for improving weld quality and its application in welding dissimilar aluminum alloys.

[0013] More specifically, the present application provides an application of an aluminum alloy welding sheet for improving weld quality in welding 6xxx series aluminum alloys and dissimilar aluminum alloys.

[0014] Optionally, the aluminum alloy welding sheet may be used to weld dissimilar aluminum alloy parent materials consisting of A356 aluminum alloy and 6xxx aluminum alloy, or dissimilar aluminum alloy parent materials consisting of 6082 aluminum alloy and 6xxx aluminum alloy.

[0015] Optionally, the composition of the 6xxx series aluminum alloy is as follows, by mass percentage: Si 1%~1.5%, Mg 0.8%~1%, Mn 0.4%~0.5%, Cr 0.3%~0.5%, Fe 1%~1.5%, Cu 0.3%~0.5%, Zn<0.1%, and the balance is Al and inevitable trace elements.

[0016] In summary, this application has the following beneficial effects: The aluminum alloy welding sheet provided by the present invention can better fill micropores and defects in the weld during the melting process, reduce the presence of pores and inclusions, and improve the density of the weld, thereby enhancing the weld's sealing and corrosion resistance. The appropriate welding sheet composition can be well matched with the weldment material, improving the weld strength through metallurgical bonding. The alloying elements in the welding sheet can diffuse and fuse with the weldment metal, forming a weld structure with sufficient strength and toughness, making the mechanical properties of the weld joint closer to or better than the weldment itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the weld joint structure in Example 1 of the present invention; Figure 2 This is the weld joint structure in Example 2 of the present invention. DETAILED DESCRIPTION

[0018] In the field of welding technology, once the base metal is determined, the selection of welding parameters becomes a key factor influencing the microstructure and mechanical properties of the welded joint. By adding welding chips during welding to promote alloy melting and form a good weld joint, various elements are introduced to control the weld composition and improve weld quality.

[0019] As an intermediate layer during welding, the welding sheet melts during the welding process, filling the gaps between the parent metals and ensuring a continuous metal structure at the weld. This is crucial for maintaining the integrity of the weld joint, enabling the welded components to withstand the corresponding external forces without breaking or separating. The welding sheet works in conjunction with the welding wire to control the weld structure and thereby improve the weld's mechanical properties.

[0020] Based on this, the inventors formed the present invention by adjusting the types and proportions of elements in the solder sheet. The technical solution of the present invention will be further explained and illustrated in conjunction with specific embodiments and drawings. It should be clear that the specific embodiments presented here are only intended to assist in understanding the present invention and do not constitute a specific limitation on the present invention. In addition, the drawings used herein are only for the purpose of more effectively displaying the contents disclosed by the present invention and do not have a restrictive effect on the scope of protection. Unless otherwise stated, the raw materials selected in the embodiments of the present invention are all raw materials commonly used in this field, and the methods used in the embodiments are also conventional methods in this field.

[0021] Example 1 Example 1 provides an aluminum alloy welding sheet for improving the weld quality of dissimilar aluminum alloy welds. The sheet comprises the following components, by weight percentage: 4.5% Si, 3.5% Mg, 2% Mn, 0.4% Cr, 2.6% Fe, and 0.2% Cu, with the remainder being Al and less than 0.5% other unavoidable impurity elements. The raw materials for the sheet are industrially pure aluminum, industrially pure magnesium, an Al-20% Si master alloy, an Al-10% Fe master alloy, an Al-15% Cu master alloy, an Al-10% Mn master alloy, and an Al-5% Cr master alloy, prepared according to the above formulation. The sheet is prepared using the following method: Step S1: melting industrial pure aluminum, industrial pure magnesium, Al-20% Si master alloy, Al-10% Fe master alloy, Al-15% Cu master alloy and Al-10% Mn master alloy and continuously stirring at a melting temperature of 840°C; Step S2: Use a metallurgical slag removal device to remove slag, add Al-5%Cr master alloy after it is completely melted, continue smelting and stirring, and the stirring time is 30 minutes; Step S3: The melt is refined and degassed by introducing argon at a flow rate of 2 L / min to remove gases and impurities in the metal, such as hydrogen and oxides; Step S4: After refining, the metal is cast and then allowed to cool naturally in the mold to room temperature. During the cooling process, rapid cooling should be avoided to prevent internal stress and cracks. After the metal is completely cooled, demolding is performed and the blank is taken out to obtain the welding piece; Step S5: rolling the welding sheet blank to achieve the desired thickness through multiple rolling passes, while improving the structure and performance of the welding sheet. During the rolling process, the rolling pressure, rolling speed and rolling temperature must be controlled, and the rolling temperature is 400°C. Annealing the rolled welding sheet can eliminate the internal stress generated during the rolling process and improve the plasticity and toughness of the welding sheet. The annealing temperature and time are determined according to the material and thickness of the welding sheet. The annealing temperature is 450°C and the annealing time is 2.5 hours. Step S6: Finally, the processed solder pad is subjected to surface treatment, such as cleaning, polishing, and coating. Cleaning removes oil and impurities from the solder pad surface; polishing makes the solder pad surface smoother and flatter, improving contact performance during welding; and coating forms a protective film on the solder pad surface to prevent oxidation or corrosion during storage and use. The final solder pad has a size of 100 mm × 3 mm × 0.4 mm.

[0022] The aluminum alloy welding sheet prepared in Example 1 was used to weld 6082 aluminum alloy and a 6xxx series aluminum alloy. The 6xxx series aluminum alloy had the following composition by mass: Si 1%, Mg 0.8%, Mn 0.5%, Cr 0.5%, Fe 1%, Cu 0.3%, Zn <0.1%, with the balance being Al and unavoidable trace elements. Laser-CMT hybrid oscillation welding was used, with a laser power of 3.8 kW, a welding speed of 35 m / s, and a feed rate of 4.5 m / min.

[0023] During the welding process, the welding piece refines the grains in the weld and affects the grain growth, which hinders the growth of columnar crystals, promotes the nucleation and growth of equiaxed crystals, and transforms columnar crystals into dendrites under the temperature gradient generated by laser welding. Figure 1 As shown, the alloying elements interact to form a second phase to strengthen the weld, such as the formation of Mg2Si and AlFe phases, which enhances the weld strength.

[0024] Example 2 Example 2 provides an aluminum alloy welding sheet for improving the weld quality of dissimilar aluminum alloy welds. The sheet comprises, by weight, 5% Si, 3% Mg, 2.2% Mn, 0.8% Cr, 2.2% Fe, and 0.4% Cu, with the remainder being Al and less than 0.5% other unavoidable impurity elements. The raw materials and preparation method for the aluminum alloy welding sheet in Example 2 are the same as those in Example 1 and are therefore not further described.

[0025] The aluminum alloy welding sheet prepared in Example 2 was used to weld A356 aluminum alloy and a 6xxx series aluminum alloy. The 6xxx series aluminum alloy comprises, by mass, 1.5% Si, 1% Mg, 0.4% Mn, 0.3% Cr, 1.5% Fe, 0.5% Cu, and less than 0.1% Zn, with the balance being Al and unavoidable trace elements. Laser-CMT oscillation hybrid welding was used, with a laser power of 2.5 kW, a welding speed of 35 m / s, and a feed speed of 4.5 m / min.

[0026] During the welding process, the weld filler is melted and fills the gap between the base materials, ensuring a continuous metal structure at the weld, maintaining the integrity of the weld joint, and allowing the two base materials to be firmly connected. The high content of Mg in the weld filler gives the joint a higher degree of undercooling, thereby refining the grains. At the same time, Mg changes the thermal conductivity and thermal gradient transfer of the weld pool, inhibiting the growth of α-Al grains during the solidification process of the weld pool. Figure 2 As shown in the figure, the main phases formed in the weld and fusion zone include α-Al, Al-Si eutectic, α-Al (Fe, Mn, Cr) Si phase, α-Al (Fe, Mn) Si phase, and Mg2Si phase. The Mg2Si phase is the primary strengthening phase, effectively preventing grain boundary sliding and improving the strength and hardness of the aluminum alloy. A moderate and evenly distributed α-Al (Fe, Mn, Cr) Si phase strengthens the aluminum alloy weld joint, improving its tensile strength and yield strength. The resulting phase structure and grain morphology determine the deformation and failure behavior of the weld under external forces. A moderate amount of strengthening phase can hinder dislocation motion and improve the tensile strength and yield strength of the weld joint.

[0027] This invention, for the first time, utilizes microalloyed aluminum alloy welding pads to weld A356 aluminum alloy and the aforementioned new 6xxx series aluminum alloys. During the welding operation, the core function of this invention is to fill gaps created by the melting of the parent metals during welding, thereby ensuring a continuous metal structure at the weld site. This is crucial for maintaining the integrity of the weld joint, ensuring a tight connection between the two parent metals and providing strong resistance to fracture when subjected to external forces, effectively preventing separation. The chemical composition of this invention can influence the nucleation conditions during the solidification of the weld pool. For example, certain elements can act as nuclei for heterogeneous nucleation, increasing the number of nuclei in the weld pool and thereby achieving grain refinement. While the grain refinement achieved by this invention may be slightly inferior to that achieved by welding wires rich in certain elements (such as those with a high magnesium content, which excel in grain refinement), it can still regulate grain size within a certain range. The elements contained in this invention also have the ability to alter the rate and direction of grain growth. By changing the thermal conductivity of the molten pool and the transfer of thermal gradients, the excessive growth of grains in specific directions can be restricted, making the grain growth more balanced and conducive to creating a more ideal microstructure.

[0028] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. An aluminum alloy welding sheet for improving the weld quality of dissimilar aluminum alloys, characterized in that: The steel comprises the following components by weight percentage: Si 4.5%-5%, Mg 3.0%-3.5%, Mn 2%-2.2%, Cr 0.4%-0.8%, Fe 2.2%-2.6%, Cu 0.2-0.4%, and the balance is Al and inevitable trace elements.

2. A method for preparing an aluminum alloy welding sheet for improving the quality of weld seams of dissimilar aluminum alloys as claimed in claim 1, characterized in that: The specific steps include: Step S1: melting pure aluminum, pure magnesium, Al-Si master alloy, Al-Fe master alloy, Al-Cu master alloy and Al-Mn master alloy and continuously stirring; Step S2: After slag removal, Al-Cr master alloy is added and smelting is continued; Step S3: refining and degassing the melt smelted in step S2; Step S4: Casting the material obtained in step S3 to obtain a welding blank; Step S5: rolling the welding sheet blank; Step S6: Finally, the surface is cleaned, polished and treated with an anti-oxidation coating.

3. The method for preparing an aluminum alloy welding sheet for improving the weld quality of dissimilar aluminum alloys according to claim 2, characterized in that: The melting temperature in step S1 is 820-840°C.

4. The method for preparing an aluminum alloy welding sheet for improving the weld quality of dissimilar aluminum alloys according to claim 2, characterized in that: The temperature of the rolling process in step S5 is 400°C to 500°C.

5. The method for preparing an aluminum alloy welding sheet for improving the weld quality of dissimilar aluminum alloys according to claim 2, characterized in that: The step S5 also includes an annealing process performed after the rolling process.

6. The method for preparing an aluminum alloy welding sheet for improving the weld quality of dissimilar aluminum alloys according to claim 5, characterized in that: The annealing treatment is performed at a temperature of 400-450° C. and for a time of 2-3 hours.

7. Use of the aluminum alloy welding sheet according to claim 1 in welding dissimilar aluminum alloys.

8. The use according to claim 7, characterized in that The aluminum alloy welding sheet can be used for welding dissimilar aluminum alloy base materials consisting of A356 aluminum alloy and 6xxx aluminum alloy, or dissimilar aluminum alloy base materials consisting of 6082 aluminum alloy and 6xxx aluminum alloy.

9. The use according to claim 8, characterized in that The composition of the 6xxx series aluminum alloy is as follows, by mass percentage: Si 1%~1.5%, Mg 0.8%~1%, Mn 0.4%~0.5%, Cr 0.3%~0.5%, Fe 1%~1.5%, Cu 0.3%~0.5%, Zn<0.1%, and the balance is Al and inevitable trace elements.

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