A method for fusion welding of a heterogeneous age-hardened aluminum alloy

Abstract

The application discloses a heterogeneous aging strengthening type aluminum alloy melting welding method and belongs to the technical field of melting welding. The method comprises the following steps: S1, type division and preparation of welding wires: the welding wires are divided into four types according to material hardness and are prepared; S2, pre-welding cleaning of aluminum alloy heterogeneous workpieces; S3, selection and filling of welding wire types: taking the aluminum alloy heterogeneous workpiece with higher strength as a reference, welding wires with the same or similar hardness are selected, and the filling materials are filled into the butt joint of the two aluminum alloy heterogeneous workpieces to be welded; S4, welding is performed by using a melting welding method with small heat input; and S5, post-welding treatment is performed on the welded piece. The welding wire containing heat cracking prevention particles and being consistent with the aluminum alloy with higher strength in the workpiece to be welded is selected as the filling material, on the one hand, the heat cracking prevention particles are introduced to promote the formation of small weld grain, thereby solving the problem of melting welding heat cracking.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fusion welding, in particular to a heterogeneous aging strengthening type aluminum alloy fusion welding method. BACKGROUND

[0002] Aluminum alloy has the advantages of low density, high strength, good corrosion resistance and good machinability, and is widely used in the fields of aerospace, rail transportation and mechanical equipment. The composite structure of heterogeneous aluminum alloy can fully exert the advantages of various aluminum alloys, so that the overall structure has excellent comprehensive performance. The aging strengthening type aluminum alloy generally has high alloy element content, wide solidification interval and low solidus temperature, which leads to the easy production of hot cracks during fusion welding. Therefore, the connection of heterogeneous aging strengthening type aluminum alloy is mainly achieved by friction stir welding technology. However, in the process of friction stir welding, the rigid stir pin needs to be inserted into the workpiece to be welded and moved, and the workpieces on both sides of the weld need to be given corresponding upset force. Therefore, for workpieces with complex shape and small welding space, the use of this technology is greatly limited, and its application universality is far inferior to that of fusion welding technology. SUMMARY

[0003] The purpose of the present application is to provide a heterogeneous aging strengthening type aluminum alloy fusion welding method.

[0004] To solve the above technical problems, the technical solution adopted by the present application is:

[0005] A heterogeneous aging strengthening type aluminum alloy fusion welding method, comprising the following steps:

[0006] Step S1: Type division and preparation of welding wire: divide the welding wire into four types according to the hardness of the material and prepare them:

[0007] First, the super-high-hardness welding wire includes aluminum alloy material with hardness HRC 58 or above and anti-hot-crack particles, the volume percentage of the anti-hot-crack particles in the welding wire is 1.5% to 2%, the particle size of the anti-hot-crack particles is 30 to 150 nm, and the anti-hot-crack particles are 1:1 by weight of SiC and TiB2;

[0008] Second, the high-hardness welding wire includes aluminum alloy material with hardness HRC 49 to 57 and anti-hot-crack particles, the volume percentage in the welding wire is 1.0% to 1.6%, the particle size of the anti-hot-crack particles is 30 to 150 nm, and the anti-hot-crack particles are 1:1 by weight of WC and TiB2;

[0009] Third, the medium-hardness welding wire includes aluminum alloy material with hardness HRC 39 to 48 and anti-hot-crack particles, the volume percentage in the welding wire is 0.8% to 1.2%, the particle size of the anti-hot-crack particles is 30 to 150 nm, and the anti-hot-crack particles are 1:1 by weight of SiC and WC;

[0010] The fourth is low-hardness welding wire, including aluminum alloy material with a hardness of HRC38 or less and anti-thermal cracking particles, the volume percentage of which in the welding wire is 0.5% to 1.0%, the particle size of the anti-thermal cracking particles is 30 to 150nm, and the anti-thermal cracking particles are SiC and Al2O3 in a weight ratio of 1:1;

[0011] Step S2: cleaning the aluminum alloy special-shaped workpiece before welding;

[0012] Step S3: Selecting and filling welding wire type: Compare the two aluminum alloy special-shaped workpieces to be welded, select the aluminum alloy special-shaped workpiece with higher strength, and use the aluminum alloy special-shaped workpiece with higher strength as a reference. Select a welding wire of the corresponding type with a hardness that is consistent with or close to that of the aluminum alloy special-shaped workpiece with higher strength. Use the selected welding wire as a filler material to fill the joint of the two aluminum alloy special-shaped workpieces to be welded;

[0013] Step S4: welding is performed using a melting welding method with low heat input;

[0014] Step S5: performing post-weld processing on the welded part: removing the weld reinforcement to make the weld flush with the workpieces on both sides, and then performing post-weld processing on the welded part.

[0015] The present invention improves the welding wire, adds anti-thermal cracking particles into the welding wire, and optimizes the volume ratio of the anti-thermal cracking particles in the welding wire. After using the welding wire to weld aluminum alloy special-shaped workpieces, the thermal cracking problem occurring during the welding process is significantly solved.

[0016] Preferably, in step S2, the specific cleaning method is as follows: before welding, use sandpaper to polish the areas to be welded of the two aluminum alloy special-shaped workpieces to remove the oxide film on the surface of the aluminum alloy special-shaped workpieces, and then use organic solvent acetone to scrub the polished aluminum alloy special-shaped workpieces to remove oil stains on the surface of the aluminum alloy special-shaped workpieces.

[0017] Preferably, in step S4, the fusion welding method adopted is laser-arc hybrid welding.

[0018] Preferably, when laser-arc hybrid welding is used, the angle between the laser light emitted by the laser and the surface perpendicular to the aluminum alloy special-shaped workpiece is 0-15°, and the angle between the arc welding gun and the aluminum alloy special-shaped workpiece is 30-60°.

[0019] Preferably, the current of the arc welding gun is 100-250A, the welding speed is 0.1-0.2m / s, the wire feeding speed is 6-10m / min, and high-purity argon is used as the shielding gas with a flow rate of 15-25L / min.

[0020] Preferably, in the laser, the light filament spacing of the light source is 2-4mm, the defocusing amount is -3-+3mm, and the laser power is 3-5kw.

[0021] Preferably, in the step S5, during the post-welding treatment, laser impact is first performed on the weld zone and the heat-affected zone on both sides of the weld of the aluminum alloy profiled workpiece, and then aging treatment is performed. By taking this method, high-performance fusion welding of the dissimilar aging strengthening type aluminum alloy can be realized, and the fusion welding part has excellent strength and plasticity.

[0022] Preferably, the specific steps of the laser impact are as follows: first, polishing the area subjected to laser impact, then pasting black adhesive tape as an absorbing layer, and using flowing water as a constraint layer during impact, and the thickness of the water layer is 1-2mm.

[0023] Preferably, the laser impact parameters are as follows: single pulse energy 2-9J, pulse width 18-24ns, circular light spot, diameter 2.5mm, light spot overlap rate 20%-70%, and impact times 1-4 times.

[0024] Preferably, the aging treatment adopts artificial aging or natural aging, wherein the artificial aging parameters are the same as those of the aluminum alloy with lower strength in the welded workpiece; and the natural aging is to place at room temperature for 2-16 weeks.

[0025] The beneficial effects of the present application are as follows:

[0026] In the present application, the welding wire containing the anti-heat-cracking particles and consistent with the aluminum alloy with higher strength in the workpiece to be welded is selected as the filler material, on the one hand, the anti-heat-cracking particles are introduced to promote the formation of fine grains in the weld, thereby solving the problem of heat cracking in fusion welding, and on the other hand, the dilution rate of the alloy composition of the weld is reduced, so that the weld has higher strength.

[0027] The laser-arc welding method has small heat input, and can minimize the influence of welding heat input on the heat-affected zone.

[0028] The post-welding aging treatment is directly performed, and the laser impact and aging process proposed in the present application can improve the strength of the heat-affected zone of the weak aluminum side while improving the strength of the weld, so that the weld and the heat-affected zone of the weak aluminum side maintain a large strength difference, thereby making the plastic deformation of the joint mainly concentrated in the heat-affected zone of the weak aluminum side, and making the welding area have good plasticity. BRIEF DESCRIPTION OF DRAWINGS

[0029] The present application is further described by using the drawings, but the embodiments in the drawings do not constitute any limitation on the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the following drawings:

[0030] Figure 1The state diagram of the 7075 and 6061 aluminum alloy after welding of the embodiment 1 of the present application;

[0031] Figure 2 For Figure 1 The state diagram of the welding joint after the welding flash is removed and the welding joint is flush with the two workpieces, and then the welded workpiece is subjected to post-welding treatment;

[0032] Figure 3 For Figure 2 The welding joint microstructure diagram shown in the figure;

[0033] Figure 4 The 7075 and 6061 aluminum alloy fusion welding joint strength and plasticity of the embodiment 1 of the present application and the performance of the friction stir welding joint in the literature are compared. DETAILED DESCRIPTION

[0034] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below in combination with the drawings and specific embodiments, and it should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0035] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper surface", "lower surface", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "forward rotation", "reverse rotation", "axial", "radial", "circumferential" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. Embodiment 1:

[0036] The present example discloses a heterogeneous aging strengthening type aluminum alloy fusion welding method. Two kinds of aluminum alloy profiled workpieces with the same size are selected as welding materials, one is a 7075 aluminum alloy profiled workpiece, and the other is a 6061 aluminum alloy profiled workpiece, with a length of 120 mm, a width of 100 mm, and a thickness of 3 mm.

[0037] The heterogeneous aging strengthening type aluminum alloy fusion welding method of the present example comprises the following steps:

[0038] Step S1: Type division and preparation of welding wire: the welding wire is divided into 4 types according to the material hardness and prepared:

[0039] The first is an ultrahigh-hardness welding wire, including an aluminum alloy material with a hardness of HRC 58 or above and a heat-crack-preventing particle, the volume percentage of the heat-crack-preventing particle in the welding wire being 1.5%, the particle size of the heat-crack-preventing particle being 30 nm, and the heat-crack-preventing particle being SiC and TiB2 in a weight ratio of 1:1;

[0040] The second is a high-hardness welding wire, including an aluminum alloy material with a hardness of HRC 49-57 and a heat-crack-preventing particle, the volume percentage of the heat-crack-preventing particle in the welding wire being 1.0%, the particle size of the heat-crack-preventing particle being 30 nm, and the heat-crack-preventing particle being WC and TiB2 in a weight ratio of 1:1;

[0041] The third is a medium-hardness welding wire, including an aluminum alloy material with a hardness of HRC 39-48 and a heat-crack-preventing particle, the volume percentage of the heat-crack-preventing particle in the welding wire being 0.8%, the particle size of the heat-crack-preventing particle being 30 nm, and the heat-crack-preventing particle being SiC and WC in a weight ratio of 1:1;

[0042] The fourth is a low-hardness welding wire, including an aluminum alloy material with a hardness of HRC 38 or below and a heat-crack-preventing particle, the volume percentage of the heat-crack-preventing particle in the welding wire being 0.5%, the particle size of the heat-crack-preventing particle being 30 nm, and the heat-crack-preventing particle being SiC and Al2O3 in a weight ratio of 1:1.

[0043] Step S2: cleaning of the aluminum alloy profiled workpiece before welding: the specific cleaning method is as follows: before welding, the to-be-welded area of the 7075 aluminum alloy profiled workpiece and the 6061 aluminum alloy profiled workpiece is polished using sandpaper, the oxide film on the surface of the aluminum alloy profiled workpiece is removed, and then the polished aluminum alloy profiled workpiece is scrubbed with an organic solvent acetone to remove oil stains on the surface of the aluminum alloy profiled workpiece.

[0044] Step S3: selection of the welding wire type and filling: comparing the 7075 aluminum alloy profiled workpiece and the 6061 aluminum alloy profiled workpiece, the aluminum alloy profiled workpiece with higher strength is selected as the 7075 aluminum alloy profiled workpiece, taking the 7075 aluminum alloy profiled workpiece as a benchmark, a welding wire of a corresponding type with a hardness consistent with or close to that of the aluminum alloy profiled workpiece with higher strength is selected as an ultrahigh-hardness welding wire, and the ultrahigh-hardness welding wire is used as a filling material to fill the butt joint of the 7075 aluminum alloy profiled workpiece and the 6061 aluminum alloy profiled workpiece.

[0045] Step S4: welding by using a melting welding method with small heat input: the melting welding method is laser-arc hybrid welding. When the laser-arc hybrid welding is used, the angle between the laser emitted by the laser and the surface of the aluminum alloy profiled workpiece is 0°, and the angle between the arc welding gun and the aluminum alloy profiled workpiece is 30°; the current of the arc welding gun is 100 A, the welding speed is 0.1 m / s, the wire feeding speed is 6 m / min, high-purity argon is used as the protective gas, and the flow rate is 15 L / min; in the laser, the light filament spacing of the light source is 2 mm, the defocusing amount is -3~+3 mm, and the laser power is 3 kw; the shape after welding is as shown in Figure 1

[0046] Step S5: post-welding treatment of the welded piece: the weld reinforcement is removed, the weld is flush with the two sides of the workpiece, and then the post-welding treatment of the welded piece is performed, as shown in Figure 2

[0047] In the post-welding treatment process, laser shock is first performed on the weld zone and the heat-affected zone on both sides of the weld of the aluminum alloy profiled workpiece, and then aging treatment is performed. By using this method, high-performance melting welding of dissimilar age-hardening type aluminum alloys can be achieved, and the melting welding part has excellent strength and plasticity.

[0048] The specific steps of laser shock are: first, polishing the area to be laser shocked, then pasting black tape as an absorption layer, and using running water as a constraint layer during the shock, with a water layer thickness of 1 mm; the laser shock parameters are: single pulse energy 2 J, pulse width 18 ns, circular spot diameter 2.5 mm, spot overlap rate 20%, and shock frequency 1 time.

[0049] The aging treatment adopts artificial aging or natural aging, wherein the artificial aging parameters are the same as those of the aluminum alloy with lower strength in the welded workpiece; the natural aging is to place it at room temperature for 2 weeks.

[0050] In this embodiment, the state of the welded 7075 and 6061 is as shown in Figure 1 It can be seen that no obvious cracks are observed in the weld, indicating that the scheme solves the problem of melting welding hot cracking of dissimilar aluminum alloys.

[0051] The metallographic structure of the weld zone is as shown in Figure 3 It can be seen that the grains in the weld zone are fine.

[0052] The strength and plasticity of the welding zone are compared with the performance of the friction stir welding joint in the literature, as shown in Figure 4 The part "PRESENT WORK" in the dashed box in the figure refers to the present technology, and it can be seen that the welding strength of the melting welding in this embodiment exceeds the welding strength prepared by the friction stir welding technology in the literature, while maintaining good plasticity. Example 2: ​​

[0053] The present example discloses a heterogeneous aging strengthening type aluminum alloy melting welding method. Two aluminum alloy heterogeneous workpieces of the same size are selected as welding materials, one is a 7075 aluminum alloy heterogeneous workpiece, and the other is a 2024 aluminum alloy heterogeneous workpiece, with a length of 120 mm, a width of 100 mm, and a thickness of 3 mm.

[0054] The heterogeneous aging strengthening type aluminum alloy melting welding method of the present example comprises the following steps:

[0055] Step S1: Type division and preparation of welding wire: the welding wire is divided into four types according to the hardness of the material and prepared:

[0056] First, the super-high-hardness welding wire includes aluminum alloy material with a hardness of HRC 58 or above and anti-hot-cracking particles, the volume percentage of the anti-hot-cracking particles in the welding wire is 1.75%, the particle size of the anti-hot-cracking particles is 90 nm, and the anti-hot-cracking particles are 1:1 weight ratio of SiC and TiB2;

[0057] Second, the high-hardness welding wire includes aluminum alloy material with a hardness of HRC 49-57 and anti-hot-cracking particles, the volume percentage in the welding wire is 1.3%, the particle size of the anti-hot-cracking particles is 90 nm, and the anti-hot-cracking particles are 1:1 weight ratio of WC and TiB2;

[0058] Third, the medium-hardness welding wire includes aluminum alloy material with a hardness of HRC 39-48 and anti-hot-cracking particles, the volume percentage in the welding wire is 1.0%, the particle size of the anti-hot-cracking particles is 90 nm, and the anti-hot-cracking particles are 1:1 weight ratio of SiC and WC;

[0059] Fourth, the low-hardness welding wire includes aluminum alloy material with a hardness of HRC 38 or below and anti-hot-cracking particles, the volume percentage in the welding wire is 0.75%, the particle size of the anti-hot-cracking particles is 90 nm, and the anti-hot-cracking particles are 1:1 weight ratio of SiC and Al2O3.

[0060] Step S2: Cleaning of aluminum alloy heterogeneous workpieces before welding: the specific cleaning method is as follows: before welding, first use sandpaper to polish the welding areas of the 7075 aluminum alloy heterogeneous workpiece and the 2024 aluminum alloy heterogeneous workpiece, remove the oxidation film on the surface of the aluminum alloy heterogeneous workpiece, then use organic solvent acetone to scrub the polished aluminum alloy heterogeneous workpiece, and remove the oil stains on the surface of the aluminum alloy heterogeneous workpiece.

[0061] Step S3: selection of welding wire model and filling: comparing the two 7075 aluminum alloy profiled workpieces and the 2024 aluminum alloy profiled workpiece, the aluminum alloy profiled workpiece with higher strength is selected as the 7075 aluminum alloy profiled workpiece, and the welding wire with the same or similar hardness as the 7075 aluminum alloy profiled workpiece is selected as the ultra-high hardness welding wire, which is used as the filler material to fill the butt joint of the two 7075 aluminum alloy profiled workpieces and the 2024 aluminum alloy profiled workpiece.

[0062] Step S4: welding by using a melting welding method with small heat input: the melting welding method is laser-arc hybrid welding. When the laser-arc hybrid welding is used, the angle between the laser emitted by the laser and the plane perpendicular to the aluminum alloy profiled workpiece is 8°, and the angle between the arc welding gun and the aluminum alloy profiled workpiece is 45°; the current of the arc welding gun is 175 A, the welding speed is 0.15 m / s, the wire feeding speed is 8 m / min, high-purity argon is used as the protective gas, and the flow rate is 20 L / min; in the laser, the light filament spacing of the light source is 3 mm, the defocusing amount is -3~+3 mm, and the laser power is 4 kw.

[0063] Step S5: post-welding treatment of the welded workpiece: the weld reinforcement is removed to make the weld joint flush with the two sides of the workpiece, and then the post-welding treatment of the welded workpiece is performed.

[0064] During the post-welding treatment, laser shock is first performed on the weld joint area and the heat affected zone on both sides of the weld joint of the aluminum alloy profiled workpiece, and then aging treatment is performed. This method can achieve high-performance melting welding of dissimilar age-hardened aluminum alloys, and the melting welded part has excellent strength and plasticity.

[0065] The specific steps of laser shock are: first, polishing the area to be laser shocked, then pasting black tape as an absorption layer, and using running water as a constraint layer during the shock, with a water layer thickness of 1.5 mm. The laser shock parameters are: single pulse energy 5.5 J, pulse width 21 ns, circular spot diameter 2.5 mm, spot overlap rate 45%, and shock times 3.

[0066] The aging treatment adopts artificial aging or natural aging, wherein the artificial aging parameters are the same as those of the aluminum alloy with lower strength in the welded workpiece; the natural aging is to place it at room temperature for 9 weeks. Example 3:

[0067] This example discloses a melting welding method for dissimilar age-hardened aluminum alloys. Two aluminum alloy profiled workpieces with the same size are selected as the welding material, one is a 6061 aluminum alloy profiled workpiece, and the other is a 2319 aluminum alloy profiled workpiece, with a length of 120 mm, a width of 100 mm, and a thickness of 3 mm.

[0068] The heterogeneous aging strengthening type aluminum alloy melting welding method of the present example comprises the following steps:

[0069] Step S1: Type division and preparation of welding wire: The welding wire is divided into four types according to the material hardness and prepared:

[0070] The first is super-high-hardness welding wire, including aluminum alloy material with hardness HRC 58 or above and anti-hot-cracking particles, the volume percentage of the anti-hot-cracking particles in the welding wire is 2%, the particle size of the anti-hot-cracking particles is 150 nm, and the anti-hot-cracking particles are 1:1 weight ratio of SiC and TiB2.

[0071] The second is high-hardness welding wire, including aluminum alloy material with hardness HRC 49-57 and anti-hot-cracking particles, the volume percentage in the welding wire is 1.6%, the particle size of the anti-hot-cracking particles is 150 nm, and the anti-hot-cracking particles are 1:1 weight ratio of WC and TiB2.

[0072] The third is medium-hardness welding wire, including aluminum alloy material with hardness HRC 39-48 and anti-hot-cracking particles, the volume percentage in the welding wire is 1.2%, the particle size of the anti-hot-cracking particles is 150 nm, and the anti-hot-cracking particles are 1:1 weight ratio of SiC and WC.

[0073] The fourth is low-hardness welding wire, including aluminum alloy material with hardness HRC 38 or below and anti-hot-cracking particles, the volume percentage in the welding wire is 1.0%, the particle size of the anti-hot-cracking particles is 150 nm, and the anti-hot-cracking particles are 1:1 weight ratio of SiC and Al2O3.

[0074] Step S2: Cleaning of aluminum alloy special-shaped workpieces before welding: The specific cleaning method is as follows: before welding, use sandpaper to polish the welding area of the 6061 aluminum alloy special-shaped workpiece and the 2319 aluminum alloy special-shaped workpiece, remove the oxide film on the surface of the aluminum alloy special-shaped workpiece, and then use organic solvent acetone to scrub the polished aluminum alloy special-shaped workpiece to remove oil stains on the surface of the aluminum alloy special-shaped workpiece.

[0075] Step S3: Selection of welding wire type and filling: compare the two 6061 aluminum alloy special-shaped workpieces and the 2319 aluminum alloy special-shaped workpieces to be welded, select the aluminum alloy special-shaped workpiece with higher strength as the 2319 aluminum alloy special-shaped workpiece, select the welding wire of the corresponding type with hardness consistent with or close to that of the 2319 aluminum alloy special-shaped workpiece as the super-high-hardness welding wire, and fill the selected super-high-hardness welding wire as the filling material to the butt joint of the 6061 aluminum alloy special-shaped workpiece and the 2319 aluminum alloy special-shaped workpiece.

[0076] Step S4: welding by using a melting welding method with small heat input: the melting welding method is laser-arc hybrid welding. When laser-arc hybrid welding is used, the angle between the laser emitted by the laser and the surface of the aluminum alloy profiled workpiece is 15°, and the angle between the arc welding gun and the aluminum alloy profiled workpiece is 60°; the current of the arc welding gun is 250 A, the welding speed is 0.2 m / s, the wire feeding speed is 10 m / min, high-purity argon is used as the protective gas, and the flow rate is 25 L / min; in the laser, the light filament spacing of the light source is 4 mm, the defocusing amount is -3~+3 mm, and the laser power is 5 kw.

[0077] Step S5: post-welding treatment of the welded piece: the weld reinforcement is removed to make the weld flush with the two sides of the workpiece, and then the welded piece is subjected to post-welding treatment.

[0078] During the post-welding treatment, laser shock is first performed on the weld zone of the aluminum alloy profiled workpiece and the heat-affected zone on both sides of the weld, and then aging treatment is performed. This method can achieve high-performance melting welding of dissimilar age-hardened aluminum alloys, and the melting welding part has excellent strength and plasticity.

[0079] The specific steps of laser shock are: first, polishing the area to be laser shocked, then attaching black tape as an absorbing layer, and using running water as a restraining layer during the shock, with a water layer thickness of 2 mm, laser shock parameters: single pulse energy 9 J, pulse width 24 ns, circular spot diameter 2.5 mm, spot overlap rate 70%, and shock times 4.

[0080] The aging treatment adopts artificial aging or natural aging, wherein the artificial aging parameters are the same as those of the aluminum alloy with lower strength in the welded workpiece; the natural aging is to place it at room temperature for 16 weeks.

[0081] Working principle: the present application is developed for profiled welded pieces, and the present application improves the welding wire by adding heat check prevention particles and optimizing the volume ratio of the heat check prevention particles in the welding wire. After the aluminum alloy profiled workpiece is welded by using the welding wire, the problem of heat check during welding is obviously solved.

[0082] Due to a large amount of grain boundary eutectic phase formed in the solidification process of the weld metal, the amount of solid solution atoms in the matrix is small, which leads to the weld aging strengthening effect not obvious, and the strength of the weak aluminum side heat affected zone of the two aluminum alloy special-shaped workpieces is significantly improved after aging treatment, finally leading to the strength difference between the weld and the weak aluminum side heat affected zone is reduced. Therefore, during the deformation process of the welded joint, the deformation degree difference between the weld and the weak aluminum side heat affected zone is small. Since the weld is a solidification structure, the plasticity is poor, which leads to the fracture of the welded joint in the weld zone. The laser shock and aging process proposed in the application can improve the strength of the weak aluminum side heat affected zone while improving the strength of the weld, so that the weld and the weak aluminum side heat affected zone maintain a large strength difference, so that the plastic deformation of the joint is mainly concentrated in the weak aluminum side heat affected zone. Due to the good plasticity of the weak aluminum side, the joint has good plasticity. Therefore, the method proposed in the application can realize the high-performance fusion welding of dissimilar aging strengthening type aluminum alloys, and the joint has excellent strength and plasticity.

[0083] In addition, those skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction. Although the embodiments of the application have been shown and described above, it is understood that the above embodiments are exemplary and cannot be construed as limiting the application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the application.

Claims

1. A method for melting and welding dissimilar age-hardened aluminum alloys, characterized in that: The following steps are involved: Step S1: Classification and preparation of welding wire: Welding wire is divided into 4 types according to material hardness and prepared: The first is an ultra-high hardness welding wire, which includes an aluminum alloy material with a hardness of HRC58 or above and anti-thermal cracking particles. The volume percentage of the anti-thermal cracking particles in the welding wire is 1.5% to 2%, and the particle size of the anti-thermal cracking particles is 30 to 150nm. The anti-thermal cracking particles are made of SiC and TiB2 in a weight ratio of 1:1; The second is a high-hardness welding wire, comprising an aluminum alloy material with a hardness of HRC49 to 57 and anti-thermal cracking particles, the volume percentage of which in the welding wire is 1.0% to 1.6%, the particle size of the anti-thermal cracking particles is 30 to 150nm, and the anti-thermal cracking particles are WC and TiB2 in a weight ratio of 1:1; The third type is medium-hardness welding wire, which includes aluminum alloy with a hardness of HRC39-48 and anti-thermal cracking particles. The volume percentage of the welding wire is 0.8%-1.2%, the particle size of the anti-thermal cracking particles is 30-150nm, and the thermal cracking particles are SiC and WC in a weight ratio of 1:

1. The fourth is low-hardness welding wire, including aluminum alloy material with a hardness of HRC38 or less and anti-thermal cracking particles, the volume percentage of which in the welding wire is 0.5% to 1.0%, the particle size of the anti-thermal cracking particles is 30 to 150nm, and the anti-thermal cracking particles are SiC and Al2O3 in a weight ratio of 1:1; Step S2: cleaning the heterogeneous aluminum alloy special-shaped workpiece before welding; Step S3: Selecting and filling welding wire types: Compare the two different aluminum alloy special-shaped workpieces to be welded, select the aluminum alloy special-shaped workpiece with higher strength, and use the higher strength aluminum alloy special-shaped workpiece as a reference. From the four types of welding wires in step S1, select a corresponding type of welding wire with a hardness that is consistent with or close to that of the higher strength aluminum alloy special-shaped workpiece. Use the selected welding wire as a filler material to fill the joint of the two aluminum alloy special-shaped workpieces to be welded. Step S4: welding is performed using a fusion welding method with low heat input, where the fusion welding method uses laser-arc hybrid welding; Step S5: performing post-weld treatment on the welded part: removing the weld excess height to make the weld flush with the workpieces on both sides, and then performing post-weld treatment on the welded part; during the post-weld treatment process, first performing laser shock on the weld area and the heat-affected zone on both sides of the weld of the aluminum alloy special-shaped workpiece, and then performing aging treatment; the specific steps of the laser shock are: first grinding and polishing the laser shock area, then applying black tape as an absorption layer, using running water as a constraint layer during shock, and the water layer thickness is 1~2mm; laser shock parameters: single pulse energy 2~9J, pulse width 18~24ns, using a circular spot with a diameter of 2.5mm, a spot overlap rate of 20%~70%, and the number of shocks 1~4 times.

2. The method for melting and welding dissimilar age-hardened aluminum alloys according to claim 1, characterized in that: In step S2, the specific cleaning method is as follows: before welding, use sandpaper to polish the welding areas of the two dissimilar aluminum alloy special-shaped workpieces to be welded to remove the oxide film on the surface of the aluminum alloy special-shaped workpieces, and then use organic solvent acetone to scrub the polished aluminum alloy special-shaped workpieces to remove oil stains on the surface of the aluminum alloy special-shaped workpieces.

3. The method for melting and welding dissimilar age-hardened aluminum alloys according to claim 1, wherein: When using laser-arc hybrid welding, the angle between the laser emitted by the laser and the surface perpendicular to the aluminum alloy special-shaped workpiece is 0~15°, and the angle between the arc welding gun and the aluminum alloy special-shaped workpiece is 30~60°.

4. The method for melting and welding dissimilar age-hardened aluminum alloys according to claim 3, wherein: The current of the arc welding gun is 100~250A, the welding speed is 0.1~0.2m / s, the wire feeding speed is 6~10m / min, and high-purity argon is used as the shielding gas with a flow rate of 15~25L / min.

5. The method for melting and welding dissimilar age-hardened aluminum alloys according to claim 4, characterized in that: In the laser, the filament spacing of the light source is 2-4 mm, the defocusing amount is -3-+3 mm, and the laser power is 3-5 kW.

6. The method for melting and welding dissimilar age-hardened aluminum alloys according to claim 1, wherein: The aging treatment adopts artificial aging or natural aging, wherein the artificial aging parameters are the same as the parameters of the aluminum alloy with lower strength in the aluminum alloy special-shaped workpiece to be welded; natural aging is to place it at room temperature for 2 to 16 weeks.

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