High-iron-content aluminum alloy welding wire and preparation method and application thereof

Abstract

The invention relates to a high-iron-content aluminum alloy welding wire and a preparation method and application thereof, and belongs to the technical field of welding. The aluminum alloy welding wire with the high iron content is composed of, by mass, 1.0%-3.0% of Si, 0.8%-3.5% of Fe, 1.0%-3.0% of Mn, 0.2%-1.5% of Cr, 0.2%-1.5% of V and the balance Al and other inevitable impurities. The mass ratio of Mn to Fe is 0.85 to 1.0; the mass ratio of Cr to Mn is 0.25 to 0.4; the mass ratio of (Mn + Cr) / Fe is 1.1-1.3; the mass ratio of V / (Mn + Cr) is 0.2-0.3; and the mass ratio of Si to (Fe + Mn + Cr + V) is 0.35-0.5. And the comprehensive performance of the welding seam is improved through an organization regulation mechanism.

Description

Technical Field

[0001] The present invention belongs to the technical field of welding, and in particular relates to an aluminum alloy welding wire with a high iron content, and a preparation method and application thereof. Background Art

[0002] Amid the booming lightweighting industries such as new energy vehicles, rail transit, and aerospace, aluminum alloys, with their exceptional strength-to-weight ratio, corrosion resistance, and recyclability, hold a pivotal position in structural connections. As a key consumable in aluminum alloy welding, welding wire's microstructure and properties play a decisive role in weld quality. The rapid development of high-energy beam welding technologies, such as laser welding, laser welding with filler wire, and laser-arc hybrid welding, has led to even higher demands on welding wire's adaptability, crack resistance, and structural stability.

[0003] However, most of the aluminum alloy welding wires commonly found on the market today are designed based on the Al-Si, Al-Mg, or Al-Si-Mg systems, and the Fe content is generally low, making it difficult to adapt to the metallurgical structure differences caused by the high Fe content in the recycled aluminum base material. This easily leads to the generation of needle-like β-Al5FeSi brittle phases in the weld, which seriously weakens the strength and toughness of the weld. In addition, in existing aluminum alloy welding wire designs, the comprehensive utilization rate of elements such as V, Cr, and Mn is low, and there is a lack of a systematic phase control mechanism, which makes the weld grains coarser, the crack sensitivity increases, and the porosity tendency is more obvious. These factors greatly limit the application scope of welding wire in high-efficiency, low-heat input welding scenarios.

[0004] In view of this, it has become an urgent task to develop a recycled aluminum alloy welding wire based on a high Fe system and introduce transition elements such as Mn, Cr, and V for coordinated regulation. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides an aluminum alloy welding wire with a high iron content, a preparation method and application thereof, which realizes the suppression of the brittle phase, the stable precipitation of the second phase and the refinement control of the weld grain through the structure regulation mechanism, thereby improving the comprehensive performance of the weld.

[0006] A first object of the present invention is to provide an aluminum alloy welding wire with a high iron content, wherein the element composition and mass percentage of the aluminum alloy welding wire with a high iron content are as follows: Si 1.0%-3.0%, Fe 0.8%-3.5%, Mn 1.0%-3.0%, Cr 0.2%-1.5%, V 0.2%-1.5%, and the balance Al and other inevitable impurities; A Mn / Fe mass ratio of 0.85-1.0 inhibits the formation of the harmful β-Al5FeSi phase in the weld. This condition facilitates the transformation of the β to α phase. Mn can enter the β phase lattice, destroying its structural stability and promoting its transformation into the more stable α-Al(Fe,Mn)Si phase. This improves joint toughness and reduces crack sensitivity. It also builds metallurgical phase coordination in high-iron aluminum alloy welding wires. The Cr / Mn mass ratio is 0.25-0.4, which improves the thermal stability and high-temperature deformation resistance of the weld structure. Under these conditions, Cr and Mn can jointly form the α-Al(Fe,Mn,Cr)Si stable phase. Cr has a morphology-regulating effect on the eutectic phase, transforming the coarse α phase into massive or fine particles. It also slows down the agglomeration of coarse grains and eutectics during welding thermal cycles, improving weld structure refinement and residual stress release capabilities. The mass ratio of (Mn+Cr) / Fe is 1.1-1.3. Under this condition, Fe can be used as a common impurity in recycled aluminum for metallurgical utilization and absorption. When Fe is high, it is easy to form a brittle phase and make it stably dissolved or enter the α phase. It effectively "passivates" the adverse effects of Fe in the alloy and realizes the functional reuse of Fe.

[0007] The mass ratio of V / (Mn+Cr) is 0.2-0.3; grain pinning points are formed through dispersed phases such as AlV; V can form small and stable particles such as AlV and AlVSi, which have strong grain boundary resistance. Under these conditions, fine, equiaxed, and uniform grain morphology is achieved, reducing the tendency of weld hot cracking and improving the stability of the molten pool. A too high mass ratio of V / (Mn+Cr) will lead to the precipitation of coarse particles, while a too low mass ratio will not have a significant strengthening effect. The mass ratio of Si / (Fe+Mn+Cr+V) is 0.35-0.5. Under this condition, the eutectic Si can participate in strengthening but does not induce a brittle network. It helps to form a dispersed eutectic rather than a lamellar one. It improves the plasticity of the weld and reduces the crack initiation point. It optimizes the solidification path and controls the eutectic morphology. If the mass ratio of Si / (Fe+Mn+Cr+V) is too large, a coarse eutectic Si brittle network will be formed.

[0008] In one embodiment of the present invention, the diameter of the high iron content aluminum alloy welding wire is 1.0 mm-1.2 mm.

[0009] A second object of the present invention is to provide a method for preparing the aluminum alloy welding wire with a high iron content, comprising the following steps: S1. Adding pure aluminum, Al-Si master alloy, Al-Fe master alloy, Al-Mn master alloy, Al-Cr master alloy and Al-V master alloy into a smelting furnace in proportion, melting and refining, and then standing and casting to obtain an aluminum alloy ingot; the Al-Fe master alloy is recycled aluminum with an Fe content of 1.5%-2.5%; S2. Annealing the aluminum alloy ingot described in S1, and extruding to obtain a first aluminum alloy wire having a diameter of 10 mm to 12 mm; S3. Performing multiple drawing processes on the first aluminum alloy wire described in S2, and performing intermediate annealing after each drawing process to obtain a second aluminum alloy wire having a diameter of 2.2 mm to 2.4 mm; S4. Roughly scraping, drawing, and finely scraping the second aluminum alloy wire described in S3 to obtain a third aluminum alloy wire with a diameter of 1.15 mm to 1.25 mm; S5. Surface cleaning is performed on the third aluminum alloy wire described in S4 to obtain an aluminum alloy welding wire with a high iron content.

[0010] In one embodiment of the present invention, in S1, all alloying elements (especially Si, Fe, Mn, Cr, and V) are added in the form of Al-based master alloys (e.g., Al-20Si, Al-10Mn, Al-10Cr, and Al-5V), rather than directly adding pure elements or powders. This reduces the risk of element burnout, volatilization, or reaction segregation, ensuring sufficient diffusion and stable dissolution of the alloying elements into the matrix. Furthermore, this approach ensures that elements that readily form intermetallic compounds, such as Fe, Mn, Cr, and V, act in a controlled manner on the structural evolution process in the melt, preventing the formation of premature coarse and brittle phases and improving melt stability. Furthermore, the sequential addition process can control the oxidation and volatilization losses of elements at high temperatures, effectively controlling the metallurgical reaction window of the elements, thereby improving alloying efficiency.

[0011] In one embodiment of the present invention, in S1, the melting temperature is 800°C-830°C, and the rotation speed is 150 rpm-300 rpm. This melting temperature can ensure that the alloy elements are completely dissolved while avoiding volatilization caused by overheating. In addition, elements such as V and Cr are sensitive to the oxygen content of the melt. At this melting speed, they can be quickly dispersed and the risk of local high concentration, oxidation or segregation can be reduced, avoiding the formation of coarse precipitates or inclusions, thereby improving the uniformity of element distribution and anti-segregation ability. The refining is carried out under an argon atmosphere at a gas flow rate of 1.5 L / min-2.5 L / min for 8 min-12 min; under such conditions, not only hydrogen and inclusions can be removed, but also oxidation reactions of active metal elements such as Mg and V can be suppressed; The standing time is 5-10 minutes, so that the residue and the oxide film float up and do not interfere with the distribution of elements in the melt, thereby improving the uniformity of the structure.

[0012] In one embodiment of the present invention, in S2, the annealing temperature is 450°C-470°C, and the time is 12h-16h; long-term homogenization annealing of the ingot can fully disperse the local concentrated phases (such as AlFeMnSi, AlFeMnCrSi, etc.) formed during melting, promote the re-balanced diffusion of elements such as V, Cr, and Mn in the grain boundaries and matrix, and prevent segregation or strengthening phase concentration during the drawing process; at the same time, it helps to promote the transformation of the primary phase nucleation between the cast Fe, Mn, and Cr into the thermodynamically stable α-phase, thereby interrupting the formation chain of flaky brittle phases such as β-Al5FeSi.

[0013] In one embodiment of the present invention, in S3, the diameter reduction rate of each drawing process is 5%-7%; the plastic deformation of each drawing process is relatively slow to prevent uneven migration of alloy elements; The intermediate annealing temperature is 360° C.-380° C., and the time is 1.5 h-2 h; it can alleviate work hardening, promote microstructure reconstruction and element redistribution, and maintain chemical composition uniformity.

[0014] In one embodiment of the present invention, in S3, tissue reconstruction and tissue continuity are achieved through multi-pass drawing treatment + intermediate annealing to promote microstructural stability; by controlling strain accumulation and tissue recovery, the precipitation of coarse phases of microalloying elements such as V during the drawing process is effectively avoided, thereby maintaining the final welding wire with fine structure and balanced performance.

[0015] In one embodiment of the present invention, in S4, the speed of the rough scraping is 3.5m / s-5.0m / s, and the diameter reduction is 0.10mm-0.20mm; The speed of the fine scraping is 3m / s-3.5m / s, and the diameter reduction is 0.35mm-0.55mm.

[0016] In one embodiment of the present invention, in S5, the cleaning temperature is 40°C-50°C and the cleaning time is 2min-4min; The cleaning liquid used in the cleaning is an alkaline solution or a surfactant solution.

[0017] Furthermore, the alkaline solution is a sodium hydroxide solution with a concentration of 1wt%-5wt%; The surfactant solution is sodium dodecylbenzenesulfonate solution, and the concentration is 0.2wt%-2wt%.

[0018] The third object of the present invention is to provide an application of the aluminum alloy welding wire with high iron content in aluminum alloy welding.

[0019] In one embodiment of the present invention, the aluminum alloy is selected from 4XXX series aluminum alloy and / or 6XXX series aluminum alloy.

[0020] The technical solution of the present invention has the following advantages over the prior art: The high-iron content aluminum alloy welding wire described in the present invention optimizes the Fe content and coordinates the regulation of Mn, Cr, and V, so that Fe no longer forms a brittle needle-shaped β-Al5FeSi phase, but is transformed into a spheroidized α phase or a composite phase, thereby significantly improving the plasticity and fracture toughness of the material; at the same time, a medium-low Si content design is adopted to avoid weld embrittlement caused by excessive eutectic Si while retaining good fluidity, taking into account both welding formability and joint toughness; in addition, the V element, as a significant addition, plays an important role in the welding process: it promotes grain refinement and microstructure homogenization, cooperates with Cr to form a stable Al-Fe-Cr-V phase, enhances the stability of the heat-affected zone, and reduces the width of the softening zone.

[0021] The high-iron content aluminum alloy welding wire described in the present invention reasonably controls the amount of Mn and Cr, so that Mn and Fe form an α-Al(Fe, Mn)Si phase to replace the β phase. Cr further stabilizes the α phase structure and promotes its massive and spherical precipitation. At the same time, Mn and Cr can enter the β phase lattice and disrupt its ordered structure, thereby realizing the transformation from β-Al5FeSi to α-Al(Fe, Mn, Cr)Si, greatly reducing or even eliminating the brittle β phase, and thus significantly improving the plasticity and toughness of the weld.

[0022] The high-iron aluminum alloy welding wire described herein exhibits a high degree of dispersion during rapid solidification by rationally controlling the amount of V. During this process, V combines with Al or Si to form nanoscale AlV and AlVSi particles, which are dispersed within the grains and at grain boundaries. These particles act as a second phase, exerting dispersion strengthening. Furthermore, they, along with Mn and Cr, form a multicomponent composite phase (α-Al(Fe, Mn, Cr, V)Si), which has a stable structure and resists growth or aggregation during thermal cycling, resulting in uniform distribution. During rapid cooling, these dispersed particles form multinuclear reaction centers, promoting the uniform distribution of fine precipitates and effectively improving the tensile strength and microhardness of the weld. Furthermore, these particles have multiple functions: they serve as nuclei for grain nucleation, increasing the density of equiaxed grains; and they pin grain boundary migration, preventing grain coarsening. Furthermore, due to their high thermal stability, these dispersed particles maintain their strengthening effect over the long term during welding thermal cycling, significantly enhancing the softening resistance of the weld.

[0023] Elements such as V and Cr in the high-iron aluminum alloy welding wire described in the present invention form fine particles in trace form, which play a role in grain boundary pinning and nucleation activation at the solidification front. Dispersed particles such as AlV, AlCrSi, and Al(Fe,V)Si can induce the formation of equiaxed crystals during the solidification process. Combined with the low-Si design, the coarse eutectic network structure can be reduced. The average grain size of the weld is significantly reduced, forming a uniform and fine equiaxed crystal structure. The ductility of the weld is effectively improved and the sensitivity to hot cracking is reduced.

[0024] After the high-iron aluminum alloy welding wire described in the present invention is used for aluminum alloy, the Fe element in the weld area is evenly dispersed in the form of α-Al(Fe, Mn, Cr, V)Si intermetallic compounds, and the β-Al5FeSi brittle phase is basically not detected. Because the introduced V element promotes grain refinement, the average grain size of the formed weld is less than 20μm. The welding wire does not contain or contains only trace amounts of Mg elements, avoiding the problem of hardness loss caused by Mg volatilization during welding, while maintaining good welding performance. The weld is well formed and has low crack sensitivity, with a tensile strength of up to 301MPa and a welding coefficient of 84.9%. It also has good elongation after fracture (maximum 5.1%). It constructs a weld with structural strengthening, phase control, and crack suppression capabilities through the Fe-Mn-Cr-V synergistic system, achieving a good balance of strength and toughness without relying on the high Mg strengthening mechanism.

[0025] The high-iron aluminum alloy welding wire described in the present invention forms a continuous composition gradient and a structural transition zone between the base material and the weld, thereby improving the matching and stability of the welding. Even under a high-speed cooling environment, the welding wire can form an equiaxed fine-grained structure, effectively preventing the occurrence of thermal cracks. Its surface tension is uniform and the droplet transition is stable, which is particularly suitable for thin plate, high-speed, high-energy beam welding processes, such as battery shells, aviation structures, aluminum car bodies and other precision welding applications. In addition, the welding wire makes full use of high Fe resources and improves its performance without relying on high Mg or rare precious metal elements, thereby promoting the high-value-added application of recycled aluminum, which is consistent with the national development direction of energy conservation, emission reduction and circular manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein: Figure 1 The microscopic morphology of the weld in Test Example 1 of the present invention; wherein (a) is Comparative Example 1, and (b) is Example 1; Figure 2 is the microhardness of the weld in Test Example 2 of the present invention; Figure 3The macroscopic morphology of the weld in Test Example 3 of the present invention is shown in FIG. 1 , wherein (a) is Example 1, (b) is Comparative Example 1, (c) is Comparative Example 2, and (d) is Comparative Example 3. Figure 4 These are microscopic morphologies of the weld in Test Example 3 of the present invention; wherein, (a) is Example 1, (b) is Comparative Example 1, (c) is Comparative Example 2, and (d) is Comparative Example 3. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0028] In the present invention, unless otherwise specified, the Al—Fe master alloy used in the embodiments of the present invention is recycled aluminum with an Fe content of 2%.

[0029] In the present invention, unless otherwise specified, the element composition and mass percentage of the A356 aluminum alloy used in the embodiments of the present invention are: Si: 7.92%, Mg: 0.363%, Fe: 0.124%, Mn: 0.002%, Cu: 0.004%, Zn: 0.002%, Ti: 0.119%, Ni: 0.007%, and the balance is Al and other inevitable impurities.

[0030] Example 1

[0031] The high iron content aluminum alloy welding wire and the preparation method thereof of this embodiment specifically include the following steps: S1. Pure aluminum, Al-20Si master alloy, Al-Fe master alloy, Al-10Mn master alloy, Al-10Cr master alloy, and Al-5V master alloy were added to a melting furnace in proportion and melted at 815° C. and 250 rpm. The alloys were then refined under an argon atmosphere at a gas flow rate of 1.8 L / min for 10 min, allowed to stand for 8 min, and then cast to obtain an aluminum alloy ingot. S2, homogenizing and annealing the aluminum alloy ingot at 460° C. for 14 hours, and then extruding to obtain a first aluminum alloy wire having a diameter of 11 mm; S3, performing multiple drawing processes on the first aluminum alloy wire and intermediate annealing at 370° C. for 2 hours after each drawing process to obtain a second aluminum alloy wire with a diameter of 2.3 mm; wherein the diameter reduction rate of each drawing process is 5%-7%; S4. Rough-scraping, wire drawing, and fine-scraping the second aluminum alloy wire to obtain a third aluminum alloy wire with a diameter of 1.25 mm; wherein the rough-scraping speed is 4.3 m / s and the diameter reduction is 0.15 mm; the fine-scraping speed is 3.5 m / s and the diameter reduction is 0.4 mm; S5. The third aluminum alloy wire is surface cleaned with a 4 wt % sodium hydroxide solution at a temperature of 45° C. for 3 min to obtain an aluminum alloy welding wire with a diameter of 1.2 mm and a high iron content; the elemental composition and mass percentage of the aluminum alloy welding wire with a high iron content are as follows: Si is 2.0%, Fe is 2.3%, Mn is 2%, Cr is 0.7%, V is 0.6%, and the balance is Al and other inevitable impurities.

[0032] Comparative Example 1

[0033] The method is basically the same as Example 1, except that the element composition and mass percentage of the aluminum alloy welding wire with high iron content are: Si is 2.0%, Fe is 2.3%, Mn is 2%, Cr is 0.7%, and the balance is Al and other inevitable impurities.

[0034] Comparative Example 2

[0035] The present invention is basically the same as Example 1, except that the element composition and mass percentage of the aluminum alloy welding wire with high iron content are as follows: Si is 2.0%, Fe is 2.3%, Mn is 2%, Cr is 0.7%, V is 0.3%, and the balance is Al and other inevitable impurities.

[0036] Comparative Example 3

[0037] The present invention is basically the same as Example 1, except that the element composition and mass percentage of the aluminum alloy welding wire with high iron content are as follows: Si is 2.0%, Fe is 2.3%, Mn is 2%, Cr is 0.7%, V is 0.9%, and the balance is Al and other inevitable impurities.

[0038] Comparative Example 4

[0039] The present invention is basically the same as Example 1, except that the element composition and mass percentage of the aluminum alloy welding wire with high iron content are as follows: Si is 2.0%, Fe is 2.3%, Mn is 3.5%, Cr is 0.7%, V is 0.6%, and the balance is Al and other inevitable impurities.

[0040] Comparative Example 5

[0041] The present invention is basically the same as Example 1, except that the element composition and mass percentage of the aluminum alloy welding wire with high iron content are as follows: Si is 2.0%, Fe is 2.3%, Mn is 2%, Cr is 1.8%, V is 0.6%, and the balance is Al and other inevitable impurities.

[0042] Test Example 1

[0043] The aluminum alloy welding wires prepared in Example 1 and Comparative Example 1 were used to perform laser arc hybrid welding on A356 aluminum alloy base material, with a power of 2.7 kW, a welding speed of 33 mm / s, a wire feeding speed of 4.5 m / min, an oscillation frequency of 100 Hz, and an oscillation diameter of 1.6 mm.

[0044] The welds prepared by the aluminum alloy welding wires of Example 1 and Comparative Example 1 were characterized by microscope. Figure 1 As shown. Figure 1 It can be seen from (b) that the weld fusion zone of Example 1 has no needle-shaped or flaky β-Al5FeSi brittle phase, but has a large amount of dispersed α-Al(Fe, Mn, Cr, V)Si phase; its structure is stable, without obvious segregation, and the organization is dense and uniform. This is because V cooperates with Fe and Cr during the welding solidification process to promote the transformation of Fe from irregular brittle β phase to thermally stable spherical α phase. At the same time, the average grain size of the weld of this welding wire is about 18μm, with a uniform equiaxed crystal distribution and a compact organization. Because V easily forms dispersed AlV or AlVSi particles during rapid solidification, it plays a role in grain refinement and grain boundary pinning, inhibiting grain growth. From Figure 1 As can be seen in (a), the weld fusion zone of Comparative Example 1 contains a large amount of needle- or flaky-shaped β-Al5FeSi brittle phases and a small amount of α-Al(Fe,Mn,Cr)Si phase. The weld is structurally unstable, with a coarse and uneven structure and a small amount of pores and cracks. This is because Comparative Example 1 does not introduce the element V, thus avoiding the formation of pores caused by AlV supersaturation precipitation. While traditional multi-component alloy systems offer good formability and wettability during molten pool solidification, they lack the ability to achieve grain refinement, dispersion strengthening, and control deleterious phases. This results in a high amount of residual β-Al5FeSi phase in the weld, a coarse structure, and poor performance.

[0045] Test Example 2

[0046] The microhardness distribution of the welds prepared by the aluminum alloy welding wires of Example 1 and Comparative Example 1 was tested, and the results are as follows: Figure 2 As shown. Figure 2It can be seen that the microhardness of the weld prepared by the aluminum alloy welding wire of Example 1 is higher than that of Comparative Example 1, and the fluctuation is small. The microhardness of the weld center is about 95HV, and the microhardness of the heat-affected zone is about 80HV. During the solidification process of the molten pool, V participates in the formation of fine precipitation phases such as AlV or AlVSi. These particles can serve as grain nucleation cores or pinning points under rapid cooling conditions, preventing grain boundary migration, inhibiting grain growth, and making the fine-grained structure more uniform, thereby increasing hardness and reducing local softening zones. At the same time, V works together with Fe, Mn, and Cr to transform the β-Al5FeSi brittle phase that is originally easy to form into a stable α-phase complex, making the weld structure denser and reducing crack sources and micropores. In addition, V can also increase the supercooling of the molten pool, which helps to quickly form a fine-grained structure. The uniform solidification structure can reduce the tendency of thermal cracks and residual stress concentration, and indirectly maintain the mechanical properties of the weld area. Through dispersion strengthening and microstructure refinement, V contributes to improved weld strength and toughness, resulting in uniform weld formation without significant macroscopic defects such as undercuts, pores, and cracks. At the end of solidification, V enhances weld pool interface stability, improves interfacial tension and wettability, and significantly suppresses the porosity and cracking common in laser welding. In summary, V significantly improves the mechanical properties of welds through a triple mechanism of "brittle phase suppression, grain refinement, and dispersion strengthening."

[0047] Test Example 3

[0048] The macroscopic and microscopic morphologies of the welds prepared by the aluminum alloy welding wires of Example 1 and Comparative Examples 1-3 are as follows: Figure 3-Figure 4 As shown. Figure 3-Figure 4It can be seen that the weld structure of Example 1 has fewer pores, dense structure, and good fusion; this is because the addition of an appropriate amount of V can effectively and synergistically strengthen grain control, inhibit the formation of brittle phases, and promote the release of gas in the molten pool. At the same time, it can also generate dispersed AlV / AlVSi particles, thereby promoting grain refinement, making the molten pool flow more uniform, and gas release more unobstructed. The weld structure of Comparative Example 1 has fewer pores and a coarse structure. This is because no V is added and there is a lack of a grain refinement mechanism. Although the high Si content improves wettability and is beneficial to the suppression of pores, the lack of dispersion strengthening and grain regulation leads to a coarse structure, thereby weakening the mechanical properties. The weld structures of Comparative Examples 2-3 have dense pores and discontinuous structures. This is because the mass ratio of V / (Mn+Cr) is too small, too large, or the mass ratio of Si / (Fe+Mn+Cr+V) is too small, which destroys the stability of the molten pool and the solidification behavior; in Comparative Example 2, the mass ratio of V / (Mn+Cr) is too small, which cannot play a role in stabilizing the crystal nucleus, resulting in serious molten pool segregation and insufficient gas release at the end of solidification; in Comparative Example 3, the mass ratio of V / (Mn+Cr) is too large and the mass ratio of Si / (Fe+Mn+Cr+V) is too small, forming coarse AlV / AlVSi agglomerated phases, which serve as pore cores or disrupt flow, resulting in a large number of pores; the overall interface and organizational consistency are poor, which is reflected in the weld reliability and performance fluctuations.

[0049] Test Example 4

[0050] The welds prepared from the aluminum alloy welding wires of Example 1 and Comparative Examples 1-5 were tested for yield strength, tensile strength, etc.: (1) Tensile strength, yield strength, and elongation after fracture: The samples were cut into dog-bone-shaped specimens with a length of 32 mm, a thickness of 3 mm, and a width of 6 mm. Mechanical properties were tested using a Zwick electric universal material testing machine at room temperature with a tensile strain rate of 1×10 -3 s -1 ,Each set of conditions was tested three times; (2) Average hardness: The average hardness test was performed using a Wilson VH1102 automatic hardness tester with a load of 0.98 N for 10 s. The measurement was performed along a line of the entire weld joint with a spacing of 1 mm between adjacent indentations. (3) Welding coefficient: the ratio of the tensile strength of the weld to the tensile strength of the base material; Table 1 shows the relevant properties of the weld finally measured: Table 1

[0051] As can be seen from Table 1, the weld of the embodiment has excellent mechanical properties, with a tensile strength of 301 MPa, an elongation after fracture of 5.1%, and an average hardness of 96.7 HV. This is because an appropriate proportion of V plays a key role in the solidification process of the weld, forming small and dispersed AlV or AlVSi particles. During rapid cooling, these particles act as equiaxed crystal nuclei and form "pinning sites" at the grain boundaries, effectively inhibiting grain growth while playing a role in second-phase dispersion strengthening. In addition, the presence of V can also adjust the surface tension of the molten pool metal, improve the stability of the molten pool and the uniformity of element distribution, thereby making the weld structure denser and more uniform. Moreover, V interacts with Fe, Mn, and Cr, accelerating the transformation of β-Al5FeSi to α-Al(Fe, Mn, Cr, V)Si, forming spherical or blocky stable intermetallic compounds, thereby avoiding the appearance of brittle β phase, and providing a strong guarantee for the improvement of weld plasticity and strength.

[0052] Comparing Example 1 and Comparative Example 1, it can be seen that without the addition of V, the strength, plasticity, and hardness of the weld are significantly reduced. Although Mn and Cr have a certain ability to regulate Fe, they lack the microstructure refinement and dispersion strengthening effects of V. More importantly, the lack of V leads to grain coarsening, the residual brittle β phase cannot be completely transformed, and the toughness is subsequently reduced. At the same time, although the high Si content increases the amount of eutectic Si and improves the hardness, it also exacerbates the embrittlement of the weld and further weakens the plasticity.

[0053] Comparing Example 1 and Comparative Example 2, it can be seen that when the V / (Mn+Cr) mass ratio is less than 0.2, the weld strength, ductility, and hardness are generally reduced. This is because the V / (Mn+Cr) mass ratio is too low, resulting in insufficient AlV-based dispersed phases, limited grain refinement, and discontinuous strengthening phases. Furthermore, the microstructure improvement effect is not significant, and coarse grains or irregular phase aggregation still exist.

[0054] Comparing Example 1 and Comparative Example 3, it can be seen that when the mass ratio of V / (Mn+Cr) is greater than 0.3 and the mass ratio of Si / (Fe+Mn+Cr+V) is less than 0.36, the strength, plasticity, and hardness of the weld are still poor. This is because the solid solubility of V in Al is low, which easily forms coarse, brittle AlV phases or V-rich phase agglomerates, which can become the cores of cracks or pores. Furthermore, excessive V also forms supersaturated AlVSi impurity particles with Si, which release gases (such as hydrogen) in the late solidification stage, thereby inducing pores. Furthermore, the excess secondary phases also disrupt the continuity of the microstructure, thereby reducing the elongation of the weld.

[0055] Comparing Example 1 and Comparative Example 4, it can be seen that when the Mn content exceeds 3.0%, the strength, ductility, and hardness of the weld are also poor. This is because a Mn content exceeding 3.0% leads to an excessive number and increased size of the α-Al(Mn,Fe)Si phase, which disrupts the uniformity of the microstructure and reduces the tensile strength, elongation, and fracture ductility of the material. Furthermore, a high Mn content increases oxidation tendency and promotes the formation of manganese oxide inclusions, which in turn affects the density and reliability of the weld.

[0056] Comparing Example 1 and Comparative Example 5, it can be seen that when the Cr content is greater than 1.5%, the strength, plasticity, and hardness of the weld are still poor. This is because when the Cr content is greater than 1.5%, on the one hand, it forms intermetallic compounds such as Al7Cr and (Cr, Mn)-rich phases with Fe and Si. These phases are large in size and unevenly distributed, which can easily induce cracks or reduce fatigue performance at stress concentration points; on the other hand, high Cr content will reduce the fluidity and wettability of the weld, because Cr increases the melt viscosity, resulting in poor weld fluidity, affecting formability, overlap, and weld appearance quality. Therefore, although Cr can refine grains, when the content exceeds the critical value, it will inhibit the formation of grain boundaries, resulting in coarse grains, which is not conducive to structural homogenization.

[0057] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A high iron content aluminum alloy welding wire, characterized in that: The element composition and mass percentage of the high iron content aluminum alloy welding wire are as follows: Si 1.0%-3.0%, Fe 0.8%-3.5%, Mn 1.0%-3.0%, Cr 0.2%-1.5%, V 0.2%-1.5%, and the balance Al and other inevitable impurities; The mass ratio of Mn / Fe is 0.85-1.0; The mass ratio of Cr / Mn is 0.25-0.4; The mass ratio of (Mn+Cr) / Fe is 1.1-1.3; The mass ratio of V / (Mn+Cr) is 0.2-0.3; The mass ratio of Si / (Fe+Mn+Cr+V) is 0.35-0.

5.

2. The aluminum alloy welding wire with high iron content according to claim 1, characterized in that: The diameter of the aluminum alloy welding wire with high iron content is 1.0 mm to 1.2 mm.

3. The method for preparing the aluminum alloy welding wire with high iron content according to claim 1 or 2, characterized in that: The following steps are involved: S1. Adding pure aluminum, Al-Si master alloy, Al-Fe master alloy, Al-Mn master alloy, Al-Cr master alloy and Al-V master alloy into a smelting furnace in proportion, melting and refining, and then standing and casting to obtain an aluminum alloy ingot; the Al-Fe master alloy is recycled aluminum with an Fe content of 1.5%-2.5%; S2. Annealing the aluminum alloy ingot described in S1, and extruding to obtain a first aluminum alloy wire having a diameter of 10 mm to 12 mm; S3. Performing multiple drawing processes on the first aluminum alloy wire described in S2, and performing intermediate annealing after each drawing process to obtain a second aluminum alloy wire having a diameter of 2.2 mm to 2.4 mm; S4. Roughly scraping, drawing, and finely scraping the second aluminum alloy wire described in S3 to obtain a third aluminum alloy wire with a diameter of 1.15 mm to 1.25 mm; S5. Surface cleaning is performed on the third aluminum alloy wire described in S4 to obtain an aluminum alloy welding wire with a high iron content.

4. The method for preparing the aluminum alloy welding wire with high iron content according to claim 3, characterized in that: In S1, the melting temperature is 800°C-830°C, and the rotation speed is 150rpm-300rpm; The refining is carried out under an argon atmosphere at a gas flow rate of 1.5 L / min to 2.5 L / min for 8 min to 12 min; The standing time is 5 min-10 min.

5. The method for preparing the aluminum alloy welding wire with high iron content according to claim 3, wherein: In S2, the annealing temperature is 450° C.-470° C., and the annealing time is 12 h-16 h.

6. The method for preparing the aluminum alloy welding wire with high iron content according to claim 3, wherein: In S3, the diameter reduction rate of each drawing process is 5%-7%; The intermediate annealing temperature is 360° C.-380° C., and the time is 1.5 h-2 h.

7. The method for preparing the aluminum alloy welding wire with high iron content according to claim 3, wherein: In S4, the speed of the rough scraping is 3.5m / s-5.0m / s, and the diameter reduction is 0.10mm-0.20mm; The speed of the fine scraping is 3m / s-3.5m / s, and the diameter reduction is 0.35mm-0.55mm.

8. The method for preparing the aluminum alloy welding wire with high iron content according to claim 3, wherein: In S5, the cleaning temperature is 40°C-50°C and the cleaning time is 2min-4min; The cleaning liquid used in the cleaning is an alkaline solution or a surfactant solution.

9. Use of the aluminum alloy welding wire with high iron content as claimed in claim 1 or 2 in aluminum alloy welding.

10. The use according to claim 9, characterized in that The aluminum alloy is selected from 4XXX series aluminum alloy and / or 6XXX series aluminum alloy.

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