Aluminum alloy welding wire and preparation method and application thereof

Abstract

The invention discloses an aluminum alloy welding wire as well as a preparation method and application thereof. The aluminum alloy welding wire comprises 6.2-10.5 wt.% of silicon; 2.2 to 3.7 wt.% of magnesium; 0.1 to 2.0 wt.% of copper; 0.1 to 2.4 wt.% of manganese; 0.1 to 0.5 wt.% of zinc; 0.01 to 0.1 wt.% of strontium; the total amount of the welding wire is 100 wt.% by adjusting the content of aluminum; in a welding joint formed by welding the aluminum alloy welding wire, the average hardness of a welding seam is greater than the average hardness of a welding heat affected zone; during preparation, a welding wire cast ingot is firstly prepared, and then the steps of homogenization treatment, hot extrusion, drawing and the like are carried out; experimental results show that when the aluminum alloy welding wire is used for welding aluminum alloy, a weld joint has excellent mechanical properties such as high strength and high hardness, and the welding joint coefficient is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal material welding, and in particular to an aluminum alloy welding wire and a preparation method and application thereof. Background Art

[0002] Aluminum alloys are widely used in the automotive, shipbuilding, aerospace and other fields due to their low density, high specific strength and high specific stiffness. The diversity of applications means that different methods are needed to connect aluminum alloy parts. Fusion welding is the main method for connecting aluminum alloy parts. In this process, suitable filler materials are needed to ensure that the welded joint has sufficient strength, ductility and other properties to meet the service requirements of aluminum alloy structures, and to minimize welding defects such as pores and thermal cracks.

[0003] At present, the 4XXX series (Al-Si series) aluminum alloy welding wires commonly used in industry are mainly ER4043 and ER4047. ER4043 is a hypoeutectic Al-Si alloy, which is widely used in the welding of 6XXX series aluminum alloys; compared with ER4043, ER4047 is a eutectic Al-Si alloy with a lower melting point, a small solidification range, good fluidity, and a relatively better overall welding effect; however, the mechanical properties of the welded joints corresponding to these two welding wires strongly depend on the composition of the diluted parent material, and the maximum strength of the welded joint can only reach about 70% of the strength of the 6XXX series aluminum alloy parent material, and may even be as low as 50%, which cannot meet the welding manufacturing needs of high-end equipment. Summary of the invention

[0004] The object of the present invention is to overcome one or more deficiencies in the prior art and to provide an improved aluminum alloy welding wire, wherein when the aluminum alloy welding wire is used to weld aluminum alloy, the weld has excellent mechanical properties, such as high strength, high hardness and high fatigue strength.

[0005] The present invention also provides a method for preparing the aluminum alloy welding wire and its application in laser welding, laser wire filling welding, laser-arc hybrid welding and additive manufacturing of aluminum alloy wires.

[0006] The present invention further provides an aluminum alloy product having a welded joint formed by the welding wire.

[0007] To achieve the above object, a technical solution adopted by the present invention is: an aluminum alloy welding wire, measured by weight percentage, the aluminum alloy welding wire comprises:

[0008] 6.2 wt.% to 10.5 wt.% silicon (Si);

[0009] 2.2 wt.% to 3.7 wt.% magnesium (Mg);

[0010] 0.1 wt.% to 2.0 wt.% copper (Cu);

[0011] 0.1 wt.% to 2.4 wt.% manganese (Mn);

[0012] 0.1 wt.% to 0.5 wt.% zinc (Zn);

[0013] 0.01 wt. % to 0.1 wt. % of strontium (Sr);

[0014] Less than or equal to 0.15wt.% of iron (Fe) and inevitable impurity elements, the total amount of the aluminum alloy welding wire is 100wt.% by adjusting the content of aluminum (Al);

[0015] In the welded joint formed by welding with the aluminum alloy welding wire, the average hardness of the weld is greater than the average hardness of the welding heat affected zone.

[0016] According to some specific aspects of the present invention, the welding is used to connect aluminum alloy parts.

[0017] According to the present invention, when the aluminum alloy welding wire is used to weld 6XXX series aluminum alloy, the magnesium content in the weld is 0.8wt.% to 1.5wt.%, Mg is fully dissolved in the weld and a small amount of Mg is combined with Si to form Mg2Si phase, so that the weld has high hardness.

[0018] According to some specific aspects of the present invention, the welding can be used for welding the same or different alloys among Al-Cu alloys, Al-Mg-Si alloys, Al-Zn alloys and Al-Si alloys.

[0019] According to some preferred aspects of the present invention, the average hardness of the weld in the weld joint is greater than the average hardness of the weld heat affected zone by more than 5 HV.

[0020] In some embodiments of the present invention, the average hardness of the weld in the weld joint can reach 98 HV or above.

[0021] According to some preferred aspects of the present invention, the structure of the weld includes an α-Al matrix, eutectic Si, an α-AlFeMnSi phase, a π-AlFeMgSi phase and a strip-shaped Mg2Si phase.

[0022] According to the present invention, the weld joint coefficient of the weld joint is greater than 75%.

[0023] In some embodiments of the present invention, the microstructure of the aluminum alloy welding wire includes an α-Al matrix, eutectic Si, an α-AlFeMnSi phase, a π-AlFeMgSi phase, and a skeleton Mg2Si phase;

[0024] The volume fraction of the α-Al matrix is ​​not less than 48%.

[0025] In some embodiments of the present invention, the aluminum alloy welding wire comprises, by weight percentage:

[0026] 7.0 wt. % to 10.0 wt. % silicon;

[0027] 2.6 wt. % to 3.5 wt. % magnesium;

[0028] 0.2 wt. % to 1.8 wt. % copper;

[0029] 0.1 wt. % to 2.0 wt. % manganese;

[0030] 0.1 wt.% to 0.2 wt.% zinc;

[0031] 0.01 wt. % to 0.1 wt. % of strontium;

[0032] The content of iron and inevitable impurity elements is less than or equal to 0.15wt.%, and the total amount of the aluminum alloy welding wire is 100wt.% by adjusting the content of aluminum.

[0033] Furthermore, the aluminum alloy welding wire comprises, by weight percentage:

[0034] 7.0 wt. % to 8.5 wt. % silicon;

[0035] 3.2 wt. % to 3.5 wt. % magnesium;

[0036] 1.5 wt. % to 1.8 wt. % copper;

[0037] 0.1 wt. % to 0.5 wt. % manganese;

[0038] 0.1 wt. % to 0.18 wt. % zinc;

[0039] 0.01 wt. % to 0.1 wt. % of strontium;

[0040] The content of iron and inevitable impurity elements is less than or equal to 0.15wt.%, and the total amount of the aluminum alloy welding wire is 100wt.% by adjusting the content of aluminum.

[0041] Another technical solution provided by the present invention is a method for preparing the aluminum alloy welding wire described above, the method comprising:

[0042] After selecting raw materials according to the component ratio, an aluminum alloy welding wire ingot is made, and then a homogenization treatment and hot extrusion are performed to obtain an aluminum alloy welding wire blank; the obtained aluminum alloy welding wire blank is drawn for multiple passes, and multiple intermediate annealing treatments are performed in the process to obtain an aluminum alloy welding wire, and then a surface treatment is selectively performed.

[0043] In some embodiments, an intermediate annealing treatment is performed every time the drawing deformation reaches 45%-55%.

[0044] According to some preferred aspects of the present invention, the hardness of the aluminum alloy welding wire ingot is not less than 90 HV.

[0045] According to some preferred aspects of the present invention, the homogenization treatment is carried out by keeping the temperature at 500-550° C. for 8-15 hours.

[0046] According to some preferred aspects of the present invention, the temperature of the hot extrusion is 480-500°C.

[0047] According to some preferred aspects of the present invention, the number of drawing passes is 13-26, and the temperature of the intermediate annealing treatment is 400-430°C.

[0048] Another technical solution provided by the present invention is: an application of the aluminum alloy welding wire described above in laser welding, laser wire filling welding, laser-arc hybrid welding and additive manufacturing of aluminum alloy wires.

[0049] Another technical solution provided by the present invention is: an aluminum alloy product, which includes at least two welding parent materials and a welding wire for welding the at least two welding parent materials together, and the welding wire includes the aluminum alloy welding wire described above.

[0050] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0051] Based on the defects of existing welding wires used for welding aluminum alloy parts, such as insufficient strength of welding joints and welding defects (such as pores and thermal cracks), the present invention innovatively provides an improved aluminum alloy welding wire. By adjusting the formula, the present invention can control the average hardness of the weld in the welding joint formed by welding the aluminum alloy welding wire to be greater than the average hardness of the welding heat affected zone, so that after the aluminum alloy welding wire of the present invention is welded to the base material, the strength of the welding joint can reach more than 75% of the corresponding base material strength, and can even reach about 85%, which is much higher than the existing highest welding joint coefficient of about 70%. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a physical picture of the aluminum alloy welding wire in Example 1 of the present invention;

[0053] Figure 2is a cast structure diagram of the aluminum alloy welding wire ingot obtained in step S1 in Example 1 of the present invention;

[0054] Figure 3 is a cast structure diagram of the aluminum alloy welding wire ingot obtained in step S1 in Example 2 of the present invention;

[0055] Figure 4 is a cast structure diagram of the aluminum alloy welding wire ingot obtained in step S1 in Example 3 of the present invention;

[0056] Figure 5 This is a backscattered microstructure diagram of the weld center of the weld joint obtained by welding with aluminum alloy welding wire in Example 1 of the present invention;

[0057] Figure 6 This is a backscattered microstructure diagram of the weld center of the weld joint obtained by welding with aluminum alloy welding wire in Example 2 of the present invention;

[0058] Figure 7 This is a backscattered microstructure diagram of the weld center of the weld joint obtained by welding with aluminum alloy welding wire in Example 3 of the present invention;

[0059] Figure 8 This is the backscattered microstructure diagram of the weld center of the weld joint obtained after welding in Comparative Example 1;

[0060] Fig. 9 This is the backscattered microstructure diagram of the weld center of the weld joint obtained after welding in Comparative Example 2;

[0061] Fig.10 This is the backscattered microstructure diagram of the weld center of the weld joint obtained after welding in Comparative Example 3;

[0062] Fig.11 The microhardness distribution diagram of the laser welded joint of Example 1-3 at half of the plate thickness;

[0063] Fig.12 The microhardness distribution diagram of the laser welded joints of Comparative Examples 1-3 along the half of the plate thickness;

[0064] Fig.13 It is a comparison chart of the average hardness of the welds of the laser welded joints of Examples 1-3 and Comparative Examples 1-3;

[0065] Fig.14 The engineering stress-strain curves of the laser welded joints of Example 1 and Comparative Examples 1-3;

[0066] Fig.15 The engineering stress-strain curve of the laser welded joint of Example 2-3. DETAILED DESCRIPTION

[0067] The aluminum alloy welding wire provided by the present invention can show excellent performance when welding aluminum alloy parts. For example, the average hardness of the weld in the formed weld joint can be greatly improved, and the performance of the welding heat affected zone after welding with the existing welding wire is better than the weld. The welding heat affected zone of the aluminum alloy welding wire of the present invention can become the lowest performance point of the weld joint after welding. At the same time, surprisingly, after the aluminum alloy welding wire of the present invention is used to weld aluminum alloy parts such as 6XXX series aluminum alloys, the strength of the weld joint can reach more than 75% of the parent material strength, and can even reach about 85%, which is much higher than the existing highest welding joint coefficient of about 70%.

[0068] The main idea of ​​the present invention is:

[0069] (1) The present invention adds a specific amount of Si to the aluminum alloy welding wire. Under the system of the present invention, it can not only avoid the problem of low welding strength and coarse weld structure during use, but also avoid the problem that a large amount of Al-Si eutectic in the welding wire is enriched at the grain boundary and is not conducive to the plasticity of the welded joint. In addition, it can also ensure that the welding wire has good fluidity and is easy to shape during preparation; during the welding process, the molten pool has good fluidity, which can inhibit the generation of solidification cracks, and obtain a welded joint with strength-plasticity matching and good shaping.

[0070] (2) The present invention adds a specific content of Mg to the aluminum alloy welding wire. Under the system of the present invention: ① Under the high cooling rate of welding, it is ensured that there is enough Mg element that can be dissolved in the Al matrix to improve the strength of the weld joint; at the same time, it is avoided that the solid solution amount of Mg in the weld is reduced due to the burning of Mg element during welding, causing the performance to decrease. ② When welding high-strength 6XXX series aluminum alloys, the Mg content in the weld can be between 0.8wt.% and 1.5wt.%, Mg is fully dissolved in the weld, and a small amount of Mg combines with Si to form Mg2Si phase, ensuring that the weld has high hardness. ③ After adding the Mg element, the work hardening effect of the alloy causes cyclic sliding resistance at the crack tip, hindering the expansion of the crack; a large number of sliding systems are activated, and the solute Mg can transform the crack movement into a non-localized mode, resulting in a longer crack path before the final failure and a longer fatigue life. ④ The weld joint can be strengthened by heat treatment to obtain more excellent mechanical properties.

[0071] (3) The present invention adds a specific content of Cu to the aluminum alloy welding wire. Under the system of the present invention, it can play a role in solid solution strengthening and will not precipitate Q phase and θ phase at the grain boundary, thereby avoiding reducing the corrosion resistance of the weld.

[0072] (4) The present invention adds a specific content of Mn to the aluminum alloy welding wire. Under the system of the present invention: when the Mg element in the weld reaches the solid solubility limit, the Mn element can further improve the weld performance through solid solution strengthening, and the Mn element has a high boiling point and is not easily burned during welding. The Al6Mn phase can dissolve the impurity Fe to form the Al6(Mn,Fe) phase, reducing the adverse effect of Fe on the ductility of the welding wire. The Al6Mn phase can inhibit the recrystallization process during the welding wire processing and increase the recrystallization temperature. After homogenization treatment, the fine-sized Al6Mn phase is dispersed, which can prevent grain boundary migration, thereby refining the grain size. In addition, a certain Mn content can also prevent mold sticking during the welding wire casting process.

[0073] (5) The present invention adds a specific content of Zn to the aluminum alloy welding wire. Under the system of the present invention, Zn is solid-dissolved in the aluminum matrix to improve the solid-solution strengthening effect of the weld joint.

[0074] (6) The present invention adds a specific content of Sr to the aluminum alloy welding wire, and its addition can modify the Al-Si alloy, spheroidize the needle-shaped eutectic Si, and improve the mechanical properties of the welding wire alloy.

[0075] In addition, the Al-Si welding wire of the present invention requires little heat input during welding, and when welding high-strength heat-treatable alloys, such as 2XXX series aluminum alloys, 6XXX series aluminum alloys, and 7XXX series aluminum alloys, the softening effect of the heat-affected zone caused is relatively low.

[0076] In some embodiments, the aluminum alloy welding wire or its intermediate aluminum alloy (such as an ingot, an aluminum alloy melt, etc.) described in the present invention may have the elemental composition shown in Table 1.

[0077] Table 1

[0078] element Weight percentage (wt.%) Si 6.2～10.5 Mg 2.2～3.7 Cu 0.1～2.0 Mn 0.1～2.4 Zn 0.1～0.5 Sr 0.01～0.1 Fe ≤0.15 Al the remaining

[0079] The method for preparing the aluminum alloy welding wire provided by the present invention comprises the following steps:

[0080] S1. According to the set chemical composition of the welding wire, raw materials are prepared for smelting and casting to obtain aluminum alloy welding wire ingots; the raw materials are selected from high-purity metal aluminum, high-purity metal magnesium, high-purity metal copper and high-purity metal zinc and master alloys: aluminum-silicon master alloy, aluminum-manganese master alloy and aluminum-strontium master alloy;

[0081] S2, subjecting the ingot to homogenization annealing treatment to obtain an aluminum alloy welding wire ingot; the homogenization annealing treatment temperature is 500-550° C., and the homogenization annealing treatment holding time is 8-15 hours;

[0082] S3, removing the poorly formed parts at both ends of the ingot, peeling and hot extruding to obtain an aluminum alloy welding wire billet; the hot extrusion temperature is 480-500° C., and a wire billet with a diameter of 6-9.5 mm is obtained;

[0083] S4, drawing the wire billet for multiple passes, performing an intermediate annealing treatment every time the drawing deformation reaches 50%, to obtain an aluminum alloy welding wire; the drawing passes are 13 to 26 passes, and the intermediate annealing temperature is 400 to 430° C.;

[0084] S5. Clean the aluminum alloy welding wire to remove surface oil stains, dirt, etc. to obtain a finished welding wire; the diameter of the finished welding wire is 0.8 to 1.6 mm.

[0085] The above scheme is further described below in conjunction with specific embodiments; it should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments; the implementation conditions adopted in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0086] Unless otherwise specified in the following examples, all raw materials are commercially available or prepared by conventional methods in the art.

[0087] In the following, "T5 heat treatment" means that the aluminum alloy is cooled from the high temperature forming process without cold working and then artificially aged.

[0088] Embodiment 1:

[0089] This example provides an aluminum alloy welding wire and a preparation method thereof. According to weight percentage, the chemical composition of the aluminum alloy welding wire is: Si: 7wt.%, Mg: 2.6wt.%, Cu: 0.2wt.%, Mn: 0.1wt.%, Zn: 0.1wt.%, Sr: 0.03wt.%, Fe<0.15wt.%, and the remainder is Al and unavoidable impurity elements.

[0090] The preparation method of aluminum alloy welding wire comprises the following steps:

[0091] S1. According to the set chemical composition of the welding wire, raw materials are prepared for melting and casting to obtain aluminum alloy welding wire ingots; the raw materials are selected from high-purity metal Al, high-purity metal Mg, high-purity metal Cu and high-purity metal Zn and intermediate alloys: Al-20Si intermediate alloy, Al-10Mn intermediate alloy and Al-10Sr intermediate alloy.

[0092] S2. The ingot is subjected to homogenization annealing treatment to obtain an aluminum alloy welding wire ingot; the homogenization annealing treatment temperature is 530° C., and the homogenization annealing treatment holding time is 12 h.

[0093] S3. The poorly formed parts at both ends of the ingot are removed, and the ingot is peeled and hot extruded to obtain an aluminum alloy welding wire billet; the hot extrusion temperature is 500° C., and a wire billet with a diameter of 9.5 mm is obtained.

[0094] S4. Drawing the wire billet for multiple passes, and performing intermediate annealing treatment every time the drawing deformation reaches 50%, to obtain an aluminum alloy welding wire; the drawing passes are 16 passes, and the intermediate annealing temperature is 410°C.

[0095] S5. Clean the aluminum alloy welding wire to remove surface oil stains, dirt, etc. to obtain a finished welding wire; the diameter of the finished welding wire is 1.2 mm.

[0096] The hardness of the aluminum alloy welding wire ingot was measured (test method: using XHVT-1000Z integrated micro Vickers hardness tester for measurement, load pressure of 1.96N, loading time of 15.0s) to be 94.9±1.7HV.

[0097] A 3 mm thick Al-Mg-Si-Cu alloy profile in T5 heat treatment state is selected as the welding base material, and its specific composition is shown in Table 2:

[0098] Table 2 Chemical composition of Al-Mg-Si-Cu alloy

[0099] Si Mg Cu Cr Mn Ti Fe Zn Al 1.02wt.% 0.83wt.% 0.43wt.% 0.24wt.% 0.56wt.% 0.03wt.% 0.09wt.% 0.003wt.% margin

[0100] The surface oxide scale of two Al-Mg-Si-Cu test plates was removed, and laser butt welding was performed using the prepared aluminum alloy welding wire with a diameter of 1.2 mm. The process parameters of laser butt welding were: laser power 2700W, welding speed 50mm / s, laser beam circular swing, swing amplitude 0.6mm, swing frequency 100Hz. After welding, the weld was observed to be well formed.

[0101] Embodiment 2:

[0102] This example provides an aluminum alloy welding wire and a preparation method thereof. According to weight percentage, the chemical composition of the aluminum alloy welding wire is: Si: 9.05wt.%, Mg: 2.79wt.%, Cu: 1.23wt.%, Mn: 2wt.%, Zn: 0.13wt.%, Sr: 0.03wt.%, Fe<0.15wt.%, and the remainder is Al and unavoidable impurity elements.

[0103] The preparation method of aluminum alloy welding wire comprises the following steps:

[0104] S1. According to the set chemical composition of the welding wire, raw materials are prepared for melting and casting to obtain aluminum alloy welding wire ingots; the raw materials are selected from high-purity metal Al, high-purity metal Mg, high-purity metal Cu and high-purity metal Zn and intermediate alloys: Al-20Si intermediate alloy, Al-10Mn intermediate alloy and Al-10Sr intermediate alloy.

[0105] S2. The ingot is subjected to homogenization annealing treatment to obtain an aluminum alloy welding wire ingot; the homogenization annealing treatment temperature is 520° C., and the homogenization annealing treatment holding time is 14 h.

[0106] S3. The poorly formed parts at both ends of the ingot are removed, and the ingot is peeled and hot extruded to obtain an aluminum alloy welding wire billet; the hot extrusion temperature is 490° C. to obtain a wire billet with a diameter of 9.5 mm.

[0107] S4. Drawing the wire billet for multiple passes, and performing intermediate annealing treatment every time the drawing deformation reaches 50%, to obtain an aluminum alloy welding wire; the drawing passes are 18 passes, and the intermediate annealing temperature is 415°C.

[0108] S5. Clean the aluminum alloy welding wire to remove surface oil stains, dirt, etc. to obtain a finished welding wire; the diameter of the finished welding wire is 1.2 mm.

[0109] The hardness of the aluminum alloy welding wire ingot was measured (test method: using XHVT-1000Z integrated micro Vickers hardness tester for measurement, load pressure of 1.96N, loading time of 15.0s) to be 102±3.4HV.

[0110] 3mm thick, T5 heat-treated 6061 aluminum alloy profiles are selected as welding base materials, and their specific composition is shown in Table 3:

[0111] Table 3 Chemical composition of 6061-T5 aluminum alloy

[0112]

[0113]

[0114] The surface oxide scale of two 6061 aluminum alloy test plates was removed, and the prepared aluminum alloy welding wire with a diameter of 1.2 mm was used for laser butt welding. The process parameters of laser butt welding were: laser power 2700W, welding speed 50mm / s, laser beam circular swing, swing amplitude 0.6mm, swing frequency 100Hz. After welding, the weld was observed to be well formed.

[0115] Embodiment 3:

[0116] This example provides an aluminum alloy welding wire and a preparation method thereof. According to weight percentage, the chemical composition of the aluminum alloy welding wire is: Si: 7.70wt.%, Mg: 3.42wt.%, Cu: 1.75wt.%, Mn: 0.36wt.%, Zn: 0.12wt.%, Sr: 0.03wt.%, Fe<0.15wt.%, and the remainder is Al and unavoidable impurity elements.

[0117] The preparation method of aluminum alloy welding wire comprises the following steps:

[0118] S1. According to the set chemical composition of the welding wire, raw materials are prepared for melting and casting to obtain aluminum alloy welding wire ingots; the raw materials are selected from high-purity metal Al, high-purity metal Mg, high-purity metal Cu and high-purity metal Zn and intermediate alloys: Al-20Si intermediate alloy, Al-10Mn intermediate alloy and Al-10Sr intermediate alloy.

[0119] S2. The ingot is subjected to homogenization annealing treatment to obtain an aluminum alloy welding wire ingot; the homogenization annealing treatment temperature is 500° C., and the homogenization annealing treatment holding time is 15 h.

[0120] S3. The poorly formed parts at both ends of the ingot are removed, and the ingot is peeled and hot extruded to obtain an aluminum alloy welding wire billet; the hot extrusion temperature is 493° C., and a wire billet with a diameter of 9.5 mm is obtained.

[0121] S4. Drawing the wire billet for multiple passes, and performing an intermediate annealing treatment every time the drawing deformation reaches 50%, to obtain an aluminum alloy welding wire; the drawing passes are 14 passes, and the intermediate annealing temperature is 405°C.

[0122] S5. Clean the aluminum alloy welding wire to remove surface oil stains, dirt, etc. to obtain a finished welding wire; the diameter of the finished welding wire is 1.2 mm.

[0123] The hardness of the aluminum alloy welding wire ingot was measured (test method: using XHVT-1000Z integrated micro Vickers hardness tester for measurement, load pressure of 1.96N, loading time of 15.0s) to be 112±4.5HV.

[0124] 3mm thick, T5 heat-treated 6082 aluminum alloy profiles are selected as welding base materials, and their specific composition is shown in Table 4:

[0125] Table 4 Chemical composition of 6082-T5 aluminum alloy

[0126] Si Mg Cu Cr Mn Ti Fe Zn Al 0.90wt.% 0.67wt.% 0.04wt.% 0.01wt.% 0.49wt.% 0.03wt.% 0.09wt.% 0.003wt.% margin

[0127] The surface oxide scale of two 6082 aluminum alloy test plates was removed, and the prepared aluminum alloy welding wire with a diameter of 1.2 mm was used for laser butt welding. The process parameters of laser butt welding were: laser power 2700W, welding speed 50mm / s, laser beam circular swing, swing amplitude 0.6mm, swing frequency 100Hz. After welding, the weld was observed to be well formed.

[0128] Comparative Example 1:

[0129] The welding base material and the welding process are the same as those in Example 1, except that no welding wire is used during the welding process.

[0130] Comparative Example 2:

[0131] The welding base material and welding process are the same as those in Example 1, except that: the ER4047 welding wire produced by Lincoln Company of the United States is used in the welding process, and its specific chemical composition is shown in Table 5;

[0132] Table 5 Chemical composition of ER4047 produced by Lincoln Company, USA

[0133] Si Mg Fe Mn Cr Cu Ti Zn Al 11.0wt.% <0.1wt.% 0.2wt.% <0.1wt.% <0.1wt.% <0.1wt.% <0.1wt.% <0.1wt.% margin

[0134] Note: Mg, Mn, Cr, Cu, Ti and Zn are not main components but impurities generated under manufacturing conditions.

[0135] Comparative Example 3:

[0136] The welding base material and welding process are the same as those in Example 1, except that: the ER5183 welding wire produced by Lincoln Company of the United States is used in the welding process, and its specific chemical composition is shown in Table 6;

[0137] Table 6 Chemical composition of ER5183 produced by Lincoln Company, USA

[0138] Si Mg Fe Mn Cr Cu Ti Zn Al <0.4wt.% 5wt.% <0.4wt.% 0.5-1.0wt.% <0.1wt.% <0.1wt.% <0.15wt.% 0.25wt.% margin

[0139] Note: Cr, Cu and Ti are not main components but impurities generated under manufacturing conditions.

[0140] Performance Test Results

[0141] (1) Figure 1 This is a physical picture of the aluminum alloy welding wire in Example 1 of the present invention;

[0142] Figure 2-Figure 4 They are the microstructure diagrams of the cast welding wire alloys of Example 1 to Example 3, respectively. The microstructure of the cast welding wire alloy is mainly composed of α-Al matrix, eutectic Si, α-AlFeMnSi phase, π-AlFeMgSi phase and skeleton Mg2Si phase.

[0143] (2) Figure 5-Figure 7The microstructure of the weld center is obtained by welding with the aluminum alloy welding wire prepared in Examples 1-3. The weld structure mainly includes α-Al matrix and eutectic Si, and there is also a bright white Fe-containing phase and a small amount of strip-shaped black Mg2Si phase at the grain boundary.

[0144] The weld structure of Comparative Example 1-2 is composed of α-Al matrix, eutectic Si and bright white Fe-containing phase at the grain boundary. As the Si content in the welding wire increases, i.e. 0Si→11Si, the weld center structure ( Figure 8-Figure 9 ) The volume fraction of the precipitated phase in the weld increases significantly. Comparative Example 3 uses Al-Mg welding wire. During the welding solidification process, the Mg element dissolves in the α-Al matrix, and the weld structure is composed of the α-Al matrix and the bright white Fe-containing phase ( Fig.10 ).

[0145] (3) Microhardness measurements were performed on each laser welded joint of Examples 1-3 and Comparative Examples 1-3 at half the thickness of the plate. The microhardness distributions obtained are shown in the following table. Fig.11 and Fig.12 As shown. The average hardness of the weld in the welded joint of Example 1 is about 98.2HV, which is higher than the hardness of the over-aging zone in the heat-affected zone (~92.6HV). At this time, the heat-affected zone becomes the lowest performance point of the welded joint. Comparative Examples 1-3 all use the same base material as Example 1 for welding, and the lowest hardness point of their welded joints is the weld.

[0146] Fig.13 It is a comparison chart of the average hardness of the weld of each laser welding joint. The average hardness of the weld of the laser self-melting welding joint in Comparative Example 1 is the lowest. After the introduction of 5183 welding wire (Comparative Example 3), although the solid solution strengthening effect of the Mg element increases the average hardness of the weld, its contribution in this system is limited, and the average hardness is not improved enough. When using ER4047 welding wire (Comparative Example 2), although the volume fraction of the Si-containing precipitate phase in the weld is significantly increased, the hardness of the weld is significantly increased, but the gap with the present invention is still very significant, and the basic gap is 10HV or even more. Compared with the 4047 welding wire, the aluminum alloy welding wire provided by the present invention reduces the content of the Si element and adds the Mg element to ensure that sufficient Mg elements are dissolved into the aluminum matrix under the rapid cooling conditions of the laser, and the remaining Mg elements are precipitated in the form of Mg2Si. In addition, under the joint action of other components such as Mn and Cu, the aluminum alloy welding wire system of the present invention greatly improves the average hardness of the weld.

[0147] (4) Fig.14 and Fig.15 Room temperature tensile engineering stress-strain curves of each laser welded joint.

[0148] It is calculated that the tensile strength of the laser self-melting welding joint is the lowest, only reaching 64.6% of the tensile strength of the parent material. The comparison results of the average hardness of the weld are consistent. Based on the solid solution strengthening effect of the Mg element, the joint strength of the 5183 welding wire is improved compared with the laser self-melting welding joint. However, it is found in practice that the pores in the weld reduce the partial bearing capacity of the welded joint, so that its joint coefficient only reaches 66.4% of the parent material (Comparative Example 3). When using 4047 welding wire, the strength of the welded joint is further improved, reaching 72.8% of the strength of the parent material (Comparative Example 2). In contrast, the strength of the welded joint welded using the aluminum alloy welding wire provided by the present invention can reach 76.9% of the strength of the parent material (Example 1). Similarly, when the new aluminum alloy welding wire provided by the present invention is used to weld 6061-T5 and 6082-T5 deformed aluminum alloys, the strength of the welded joint can reach 80.7% (Example 2) and 84.9% (Example 3) of the corresponding parent material strength, respectively. The tensile properties of each laser welded joint are listed in Table 7.

[0149] Table 7 Tensile properties of laser welded joints

[0150] sample Yield strength(MPa) Tensile strength(MPa) Elongation after break (%) Joint coefficient (%) Example 1 225.5±5.9 301.3±7.7 1.5±0.1 76.9 Example 2 174.2±0.7 251.8±1.9 5.1±0.8 80.7 Example 3 199.9±1.4 279.4±1.4 2.5±0.1 84.9 Comparative Example 1 187.7±4.0 253.4±6.0 2.1±0.5 64.6 Comparative Example 2 211.7±1.5 285.2±4.8 1.6±0.2 72.8 Comparative Example 3 201.1±7.3 260.1±18.3 1.3±0.3 66.4

[0151] The above results show that the new aluminum alloy welding wire provided by the present invention can ensure that the weld has excellent mechanical properties (welding joint coefficient>75%), which is a significant improvement over the existing technology.

[0152] Note: Joint coefficient (%) = tensile strength of weld / tensile strength of parent material × 100%;

[0153] The test standards for yield strength (MPa), tensile strength (MPa) and elongation after fracture (%) are GB / T 2651-2008.

[0154] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

[0155] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

Claims

1. An aluminum alloy welding wire, characterized in that: Measured in percentage by weight, the aluminum alloy welding wire comprises: 6.2 wt. % to 10.5 wt. % silicon; 2.2 wt. % to 3.7 wt. % magnesium; 0.1 wt.% to 2.0 wt.% copper; 0.1 wt. % to 2.4 wt. % manganese; 0.1 wt.% to 0.5 wt.% zinc; 0.01 wt. % to 0.1 wt. % of strontium; Less than or equal to 0.15wt.% of iron and inevitable impurity elements, the total amount of the aluminum alloy welding wire is adjusted to 100wt.% by adjusting the aluminum content; In the welded joint formed by welding with the aluminum alloy welding wire, the average hardness of the weld is greater than the average hardness of the welding heat affected zone.

2. The aluminum alloy welding wire according to claim 1, characterized in that: The welding is used to connect aluminum alloy parts.

3. The aluminum alloy welding wire according to claim 1 or 2, characterized in that: When the aluminum alloy welding wire is used to weld 6XXX series aluminum alloy, the magnesium content in the weld is 0.8wt.% to 1.5wt.%.

4. The aluminum alloy welding wire according to claim 1 or 2, characterized in that: The welding can be used for welding the same or different alloys among Al-Cu alloys, Al-Mg-Si alloys, Al-Zn alloys and Al-Si alloys.

5. The aluminum alloy welding wire according to claim 1, characterized in that: The average hardness of the weld in the weld joint is greater than the average hardness of the weld heat affected zone by more than 5HV.

6. The aluminum alloy welding wire according to claim 1, characterized in that: The structure of the weld includes α-Al matrix, eutectic Si, α-AlFeMnSi phase, π-AlFeMgSi phase and strip Mg2Si phase.

7. The aluminum alloy welding wire according to claim 1, characterized in that: The welding joint coefficient of the welding joint is greater than 75%.

8. The aluminum alloy welding wire according to claim 1, characterized in that: The microstructure of the aluminum alloy welding wire includes an α-Al matrix, eutectic Si, an α-AlFeMnSi phase, a π-AlFeMgSi phase and a skeleton-like Mg2Si phase; The volume fraction of the α-Al matrix is ​​not less than 48%.

9. The aluminum alloy welding wire according to claim 1, characterized in that: Measured in percentage by weight, the aluminum alloy welding wire comprises: 7.0 wt. % to 10.0 wt. % silicon; 2.6 wt. % to 3.5 wt. % magnesium; 0.2 wt. % to 1.8 wt. % copper; 0.1 wt. % to 2.0 wt. % manganese; 0.1 wt.% to 0.2 wt.% zinc; 0.01 wt. % to 0.1 wt. % of strontium; The content of iron and inevitable impurity elements is less than or equal to 0.15wt.%, and the total amount of the aluminum alloy welding wire is 100wt.% by adjusting the content of aluminum.

10. The aluminum alloy welding wire according to claim 9, characterized in that: Measured in percentage by weight, the aluminum alloy welding wire comprises: 7.0 wt. % to 8.5 wt. % silicon; 3.2 wt. % to 3.5 wt. % magnesium; 1.5 wt. % to 1.8 wt. % copper; 0.1 wt. % to 0.5 wt. % manganese; 0.1 wt. % to 0.18 wt. % zinc; 0.01 wt. % to 0.1 wt. % of strontium; The content of iron and inevitable impurity elements is less than or equal to 0.15wt.%, and the total amount of the aluminum alloy welding wire is 100wt.% by adjusting the content of aluminum.

11. A method for preparing the aluminum alloy welding wire according to any one of claims 1 to 10, characterized in that: The preparation method comprises: After selecting raw materials according to the component ratio, an aluminum alloy welding wire ingot is made, and then a homogenization treatment and hot extrusion are performed to obtain an aluminum alloy welding wire blank; the obtained aluminum alloy welding wire blank is drawn for multiple passes, and multiple intermediate annealing treatments are performed in the process to obtain an aluminum alloy welding wire, and then a surface treatment is selectively performed.

12. The method for preparing the aluminum alloy welding wire according to claim 11, characterized in that: The hardness of the aluminum alloy welding wire ingot is not less than 90HV; and / or, the homogenization treatment is heat preservation at 500-550°C for 8-15h; and / or, the temperature of the hot extrusion is 480-500°C.

13. The method for preparing the aluminum alloy welding wire according to claim 11, characterized in that: The drawing process is performed in a range of 13 to 26 passes, and the intermediate annealing process is performed at a temperature of 400 to 430°C.

14. Use of the aluminum alloy welding wire according to any one of claims 1 to 10 in laser welding, laser wire-filling welding, laser-arc hybrid welding and additive manufacturing of aluminum alloy wires.

15. An aluminum alloy product, characterized in that: The aluminum alloy product comprises at least two welding parent materials and a welding wire for welding the at least two welding parent materials together, wherein the welding wire comprises the aluminum alloy welding wire according to any one of claims 1-10.

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