Al-Zn-Mg-Cu series aluminum alloy special for friction stir welding additive manufacturing and method for preparing additive printing piece through Al-Zn-Mg-Cu series aluminum alloy

Abstract

The invention provides an Al-Zn-Mg-Cu series aluminum alloy special for friction stir welding additive manufacturing and a method for preparing an additive printing piece through the Al-Zn-Mg-Cu series aluminum alloy, and belongs to the technical field of additive manufacturing of alloys. The Al-Zn-Mg-Cu series aluminum alloy for friction stir welding additive manufacturing, provided by the invention, is prepared from the following element components in percentage by mass: 5 percent to 11 percent of Zn, 1 percent to 2.5 percent of Mg, 1 percent to 2.2 percent of Cu, 0.1 percent to 1 percent of Zr, 0.1 percent to 1.5 percent of Sc, 0.1 percent to 1.2 percent of Ce, 0.1 percent to 1.5 percent of Yb and the balance of Al. According to the friction stir welding additive printing piece of the Al-Zn-Mg-Cu series aluminum alloy, the density can reach 99.99%, the yield strength can reach 500-530 MPa at the room temperature, the tensile strength can be kept at 550-590 MPa, meanwhile, the elongation at break can be kept at 15-20%, and the good elongation can still be kept while the good strength is kept.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology of alloys, and particularly relates to an Al-Zn-Mg-Cu aluminum alloy specifically for friction stir welding additive manufacturing and a method for preparing additively printed parts thereon. Background Technology

[0002] Additive manufacturing of aluminum alloys is widely used in aerospace, primarily because it achieves significant weight reduction with high specific strength / specific stiffness. It can also reduce the number of parts, connectors, and stress concentration through topology optimization and integrated structural design such as lattice / variable wall thickness, thereby improving specific load and fatigue life. AM processes (WAAM / L-DED, PBF, FSW-AM, cold spray, etc.) cover small-scale needs ranging from large integral wall panels / rib frames to precision and complex channels. They have high material utilization, low cost-to-use ratio, and require little or no tooling, shortening the R&D iteration and spare parts delivery cycle. At the same time, they support additive repair and remanufacturing of in-service components, reducing the total life cycle cost. Al-Zn-Mg-Cu alloys provide high specific strength for aerospace high-strength panels, but molten additive manufacturing (WAAM / L-DED, laser / electron beam PBF) is generally limited by bottlenecks such as thermal cracking and liquefaction sensitivity caused by melting-solidification, compositional drift and strength reduction caused by Zn / Mg volatilization, porosity and coarse columnar crystals, as well as high residual stress and deformation. PBF is also constrained by size and high preheating. Although cold spraying is performed at low temperatures, it is difficult to achieve sufficient metallurgical bonding and high density in thick-walled ribs, relying on heavy post-processing and exhibiting significant anisotropy. In contrast, friction stir welding additive manufacturing (FSW-AM), based on solid-state plastic deposition, avoids melting defects and element volatilization from a mechanistic perspective. It significantly reduces porosity and residual stress, and the interlayer metallurgy is continuous and scalable to large-size structures, possessing substantial potential to replace melting additive manufacturing and cold spraying. To further unleash this potential, there is an urgent need for a new 7-series composition specifically for FSW-AM: by optimizing the total amount and ratio of Zn / Mg to balance strength and plastic flow, reducing Cu to inhibit liquefaction and S phase, strictly controlling Fe / Si to reduce brittle inclusions, introducing Zr / Sc / Er to form stable and dispersed Al3X to inhibit recrystallization and refine the microstructure, and, if necessary, supplementing with Ag / rare earth elements to strengthen η′ precipitation and corrosion resistance; at the same time, formula constraints are imposed on torque and tool wear, matching the post-weld recoverability of T73 / T79 or RRA, significantly widening the interlayer temperature-load process window, reducing forming force heat load and defect sensitivity, and achieving higher rib height-width ratio and better fatigue / SCC resistance comprehensive performance. This new "process-material-integrated" composition makes FSW-AM not only a viable alternative, but also surpasses traditional melt additive manufacturing and cold spray forming in terms of both performance and cost in terms of structural dimensions, geometric accuracy, and service performance. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide an Al-Zn-Mg-Cu aluminum alloy specifically for friction stir welding additive manufacturing, a method for preparing additively printed parts, the printed parts, and their applications. The printed parts prepared using the Al-Zn-Mg-Cu aluminum alloy and the preparation method of this invention have high density, excellent strength and plasticity, and superior mechanical properties.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides an Al-Zn-Mg-Cu aluminum alloy specifically for additive manufacturing using friction stir welding. By mass fraction, the aluminum alloy material contains the following elemental components: Zn 5%~11%, Mg 1%~2.5%, Cu 1%~2.2%, Zr 0.1%~1%, Sc 0.1%~1.5%, Ce 0.1~1.2%, Yb 0.1~1.5%, and the remaining content is Al.

[0005] Preferably, the preparation method of the Al-Zn-Mg-Cu aluminum alloy specifically for additive manufacturing by friction stir welding includes: smelting, ingot casting, and homogenization heat treatment.

[0006] Preferably, the homogenization heat treatment method includes heating the ingot twice: first heating to 400°C and holding for 10 hours; second heating to 465°C and holding for 24 hours.

[0007] The present invention also provides a method for preparing additively printed parts from Al-Zn-Mg-Cu aluminum alloys specifically used for friction stir welding additive manufacturing, comprising: determining friction stir welding additive manufacturing tools, setting substrate preheating temperature, setting friction stir welding additive manufacturing process parameters, first layer deposition, interlayer cyclic additive manufacturing, start / stop and corner management, interlayer processing and shaping, end and finishing, heat treatment and performance recovery.

[0008] Preferably, the preheating temperature of the substrate is 700℃~1150℃.

[0009] Preferably, the additive manufacturing process parameters for friction stir welding include: a rotation speed of 280 r / min, a forward speed of 110 mm / min, and a bar feed speed of 62 mm / min.

[0010] The present invention also provides a printed part prepared by the above-described method for preparing additive printed parts.

[0011] Preferably, the printed part has a yield strength of 500-530 MPa, a tensile strength of 550-590 MPa, and an elongation at break of 15-20%.

[0012] Preferably, the printed part is free of cracks and has a density of 99.99%.

[0013] The present invention also provides the application of the additively printed parts prepared by the above-described method in the manufacturing of aerospace aluminum alloy components.

[0014] This invention employs a vacuum melting method to create metal ingots, followed by a homogenization heat treatment at 400℃+10 hours - 465℃+24 hours. The ingots are then cut into 10mm × 10mm × 300mm square bars using wire cutting, which serve as raw materials for friction stir welding additive manufacturing. Using friction stir welding additive 3D printing, a 300mm × 300mm × 100mm 7075 aluminum alloy substrate is selected. A droplet-type stirring head is used, with a substrate preheating time of 30-60 seconds, a rotation speed of 280 r / min, a feed speed of 110mm / min, and a bar feed speed of 62mm / min. The friction stir welding additive manufacturing equipment continuously stacks layers of 1mm thickness onto the substrate according to the preheating time, ultimately forming the desired printed part. The Al-Zn-Mg-Cu alloy additive parts prepared by friction stir welding can achieve a density of 99.99%, a yield strength of 500-530 MPa at room temperature, a tensile strength of 550-590 MPa, and an elongation at break of 15-20%. It can maintain good elongation while maintaining good strength.

[0015] This invention enables the successful manufacture of 3D printed components with specific shapes using friction stir welding additive manufacturing process. By adjusting different process parameters, the printed components are free of cracks and defects, and the density can reach 99.7% to 99.99%.

[0016] The components printed by the Al-Zn-Mg-Cu-Sc-Ce-Yb-Zr aluminum alloy of this invention through the additive manufacturing process of friction stir welding have a yield strength of 500~580MPa, a tensile strength of 550~590MPa, and an elongation at break of 15~20%. They maintain good strength while still maintaining good elongation. Attached Figure Description

[0017] Figure 1 OM, XRD, SEM and EDS images of Al-Zn-Mg-Cu-Sc-Ce-Yb-Zr alloy square bars; Figure 2 For friction stir welding additive manufacturing process; Figure 3 For additive manufacturing of friction stir welding samples; Figure 4 The stress-strain curves of the Al-Zn-Mg-Cu-Sc-Ce-Yb-Zr alloy; Figure 5 The images show the morphology of the grain interior and grain boundaries. Figure 6 STEM-EDS plot of Al3(Sc,Zr); Figure 7 The fracture morphology of the Al-Zn-Mg-Cu-Sc-Ce-Yb-Zr alloy. Detailed Implementation

[0018] This invention provides an Al-Zn-Mg-Cu aluminum alloy specifically for additive manufacturing using friction stir welding. By mass fraction, the aluminum alloy material contains the following elemental components: Zn 5%~11%, Mg 1%~2.5%, Cu 1%~2.2%, Zr 0.1%~1%, Sc 0.1%~1.5%, Ce 0.1~1.2%, Yb 0.1~1.5%, and the remaining content is Al.

[0019] The present invention does not have any special limitation on the source of the metal raw materials of each component, and conventional commercially available products in the field can be used.

[0020] In this invention, the preparation method of the Al-Zn-Mg-Cu aluminum alloy specifically for additive manufacturing by friction stir welding includes: smelting, ingot casting, and homogenization heat treatment.

[0021] In this invention, the preferred method for preparing the Al-Zn-Mg-Cu aluminum alloy includes: (1) weighing the corresponding mass of metal components according to the mass percentage of the alloy composition; (2) melting the weighed metal raw materials in step (1) in an induction furnace to form a qualified alloy liquid; (3) pouring the alloy liquid prepared in step (2) into a rectangular copper crucible, cooling it to form a rectangular ingot, and then performing heat treatment by homogenization method, with a homogenization regime of 400℃+10 hours-465℃+24 hours; (4) using a wire cutting device to set the cutting program and cutting the rectangular ingot into square bars of 10 mm×10 mm×300 mm; (5) taking an appropriate amount of sample, using SEM and EDS surface scanning to perform morphology and composition analysis of the powder, and using a laser particle size analyzer to perform particle size testing.

[0022] In this invention, the homogenization process is preferably to raise the furnace temperature from room temperature (25°C) to 400°C at a heating rate of 5°C / min and hold it for 10 hours, and then raise the furnace temperature to 465°C at a heating rate of 5°C / min and hold it for 24 hours.

[0023] The present invention also provides a method for preparing additively printed parts from Al-Zn-Mg-Cu aluminum alloys specifically used for friction stir welding additive manufacturing, comprising: determining friction stir welding additive manufacturing tools, setting substrate preheating temperature, setting friction stir welding additive manufacturing process parameters, first layer deposition, interlayer cyclic additive manufacturing, start / stop and corner management, interlayer processing and shaping, end and finishing, heat treatment and performance recovery.

[0024] In this invention, it is preferable to pre-alloy each component metal by melting, then make a metal ingot by vacuum melting, and then heat-treat it by homogenization. The ingot is cut into square bars by wire cutting as raw materials for friction stir welding additive manufacturing. By using the friction stir welding additive manufacturing 3D printing method, the friction stir welding additive manufacturing equipment accumulates layers of 1 mm thickness on the substrate in a cyclic stacking manner according to the preheating time, and finally forms the required printed part.

[0025] In this invention, the method for preparing additively printed parts from Al-Zn-Mg-Cu aluminum alloy specifically used for friction stir welding additive manufacturing preferably includes: (1) determining the friction stir welding additive manufacturing tool: the stirring head material of the stirring tool is selected as tungsten rhenium alloy, and the stirring head shape is teardrop-shaped; (2) setting the substrate preheating temperature: the preheating temperature is 700~1150℃; (3) setting the friction stir welding additive manufacturing process parameters: the rotation speed is 280r / min, the forward speed is 110mm / min, and the bar feeding speed is 62mm / min; (4) first layer deposition: controlling the insertion force and heat input, establishing metallurgical bonding and geometric reference with the substrate, and collecting and controlling flash / burrs; (5) interlayer cyclic additive manufacturing: layer-by-layer deposition according to the planned path—forging and densification—temperature management, bidirectional staggered or zoned construction to balance heat accumulation and residual stress; (6) start-stop and corner management: adopting slow start-stop, transition radius and local variable parameter feeding to suppress (7) Interlayer treatment and shaping: light mechanical scraping to remove oxide film and flash, rolling and milling to level, ensuring the adhesion and dimensional stability of the next layer; (8) Finishing and finishing: overall light straightening, removing flash and dimensional adjustment, so that the parts achieve the target geometry and surface quality; (9) Heat treatment and performance recovery: according to the characteristics of the 7 series, implement artificial aging and other schemes, taking into account strength and elongation, so that the parts achieve the optimal mechanical properties; (10) Take the sample cut in step (9), use different types of sandpaper and polishing liquid to perform rough grinding and polishing step by step, use scanning electron microscope to observe the microstructure characteristics, and use the water displacement method to test the component density; (11) Take the standard tensile sample cut in step (9), and then use different types of sandpaper to perform rough grinding step by step to remove oxide scale, and perform room temperature mechanical property testing according to GB228-2002 "Metallic Tensile Test Method", and use scanning electron microscope to observe the fracture morphology characteristics.

[0026] The present invention does not further limit the process steps in the method for preparing additively printed parts from Al-Zn-Mg-Cu aluminum alloys specifically used for friction stir welding additive manufacturing. Conventional preparation steps in the art can be used.

[0027] In this invention, the yield strength of the printed part is preferably 500-530 MPa, the tensile strength is preferably 550-590 MPa, and the elongation after fracture is preferably 15-20%.

[0028] In this invention, the printed part is free of cracks, and the density is preferably 99.99%.

[0029] The present invention also provides the application of the additively printed parts prepared by the above-described method in the manufacturing of aerospace aluminum alloy components.

[0030] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0031] Example 1 Preparation of additive manufacturing components for friction stir welding of Al-Zn-Mg-Cu-Sc-Ce-Yb-Zr alloys: (1) Use an ultrasonic cleaning instrument to clean various metal raw materials. The chemical composition mass percentage is as follows: Zn 6.5%, Mg 2.2%, Cu 2.2%, Zr 0.3%, Sc 1%, Ce 1%, Yb 0.5%, and the other content is Al. Prepare the raw materials according to this weight ratio, totaling 5Kg. The error of weighing various raw materials is within ±0.1g. (2) Melt the weighed metal raw materials in step (1) in an induction furnace to form qualified alloy ingots; (3) The alloy liquid prepared in step (2) is poured into a rectangular copper crucible and cooled to form a rectangular ingot. Then, heat treatment is performed by homogenization. The ingot is heated from room temperature to 400°C at a heating rate of 5°C / min and held for 10 hours. Then, the furnace temperature is heated to 465°C at a heating rate of 5°C / min and held for 24 hours. Finally, the ingot is taken out of the solution furnace and placed in water for quenching. (4) Use wire cutting equipment to set the cutting program and cut the rectangular ingot into square bars of 10 mm × 10 mm × 300 mm; (5) Take an appropriate amount of sample, use EDS surface scanning to analyze the powder composition, and use X-ray diffraction and SEM to analyze the morphology of the powder sample.

[0032] Experimental results: The ingot samples prepared above were characterized, such as... Figure 1As shown in (a), the OM plot reveals that the grain size in the copper mold is approximately 15.1 μm, and the secondary dendrite arm spacing is 17.0 μm. The crystal structure of the powder was analyzed using XRD, as shown below. Figure 1 As shown in (b), the crystalline phase content is directly related to the solid solubility of the alloying elements in α-Al. Because α-Al has the highest cooling rate, it easily forms supersaturated solid solutions, and the crystalline phase content decreases with increasing element solid solubility. The morphology of the samples was analyzed by SEM, as shown... Figure 1 As shown in (c), the Al-Zn-Mg-Cu-Sc-Ce-Yb-Zr alloy exhibits fewer intermetallic compounds and predominantly spherical morphologies due to its high cooling rate in the copper mold. Its composition was analyzed by EDS surface scanning, as shown... Figure 1 As shown in (d), Al has a relatively high content, resulting in the highest α-Al matrix content. Additionally, Cu, Zn, and other elements are uniformly distributed within the grains and at the boundaries / dendritic regions. However, a large number of Mg atoms agglomerate in the grain boundaries / dendritic regions, readily forming the MgZn2 and Al2CuMg phases, thus satisfying the pre-alloying requirements.

[0033] Example 2 Friction stir welding additive printing process and printed parts of Al-Zn-Mg-Cu-Sc-Ce-Yb-Zr alloy (1) Determination of additive manufacturing tools for friction stir welding: The stirring head material of the stirring tool is tungsten rhenium alloy, and the stirring head shape is teardrop-shaped; (2) Set the substrate preheating temperature: 700~1150℃; (3) Set the additive manufacturing process parameters for friction stir welding: rotation speed is 280 r / min, forward speed is 110 mm / min, and bar feeding speed is 62 mm / min; (4) First layer deposition: control the insertion force and heat input, establish metallurgical bond and geometric reference with the substrate, and collect and control flash / burrs; (5) Interlayer cyclic additive manufacturing: The square rods prepared in Example 1 are deposited layer by layer according to the planned path - forging and densification - temperature management, and bi-directional staggered or partitioned construction to balance heat accumulation and residual stress; (6) Start-stop and turning angle management: adopt slow start-stop, transition radius and local variable parameter material replenishment to suppress tunnel, unwelded and end depressions; (7) Interlayer treatment and shaping: Light mechanical scraping to remove oxide film and flash, and light milling to level, ensuring adhesion and dimensional stability of the next layer.

[0034] (8) Finishing and finishing: overall light straightening, removal of flash and dimensional adjustment, the parts achieve the target geometry and surface quality; (9) Heat treatment and performance recovery: The solution treatment was carried out at 470℃+1h and the aging temperature was 120℃. The hardness of the sample evolved with the extension of aging time during the aging process, so that the friction stir welding additive sample can take into account both strength and elongation, and the part can achieve the optimal mechanical properties. (10) Use different grades of sandpaper to coarsely grind the alloy sample step by step: 240 mesh, 1000 mesh, 2000 mesh, and then perform mechanical polishing for coarse and fine polishing until the alloy surface is free of obvious scratches and has a bright mirror appearance. Use the water displacement method to test the sample density and calculate the density. Use X-ray diffraction and scanning electron microscopy to observe its microstructure. (11) The alloy prepared by the above method was made into tensile specimens, and rough grinding was performed step by step with different grades of sandpaper to remove oxide scale. The room temperature tensile properties were tested with an electronic universal testing machine. The test results are shown in Table 1. (12) The fracture morphology was observed using a scanning electron microscope to evaluate its fracture mechanism.

[0035] Table 1. Room temperature tensile mechanical properties of Al-Zn-Mg-Cu-Sc-Ce-Yb-Zr alloys

[0036] Experimental results: The above-mentioned process steps for friction stir welding additive manufacturing were recorded, such as... Figure 2 As shown in (a) and (b), the entire process is stable, with good formability during printing and minimal porosity and flash. The printed samples are as follows: Figure 3 As shown, the printed parts have a high degree of fidelity to the model and exhibit a dense overall appearance.

[0037] The Al-Zn-Mg-Cu-Sc-Ce-Yb-Zr alloy prepared above was characterized and tested. The alloy sample was machined into a dumbbell shape by wire cutting, and the room temperature tensile properties of the alloy sample were tested using a universal tensile testing machine. The test results are as follows. Figure 4 As shown in the figure. Experimental results show that the Al-Zn-Mg-Cu-Sc-Ce-Yb-Zr alloy exhibits a yield strength of 504 MPa, a fracture strength of 583 MPa, and a fracture elongation of 18% when deformed at room temperature. The Al-Zn-Mg-Cu-Sc-Ce-Yb-Zr alloy possesses excellent comprehensive mechanical properties at room temperature, balancing both strength and elongation. Furthermore, the density obtained using the water displacement method reaches 99.99%.

[0038] The precipitate and dislocation distribution of the Al-Zn-Mg-Cu-Sc-Ce-Yb-Zr alloy were analyzed using TEM, such as... Figure 5 As shown, the precipitated phase size is small, and the dislocation density is high. Figure 5 (a) and (b) show the morphology of the precipitates and dislocations in the crystal of the printed component. The dislocation distribution is relatively uniform and the dislocation density is high. The η phase distribution is also relatively uniform, showing a diffuse and fine distribution. Figure 5 (c) and (b) show the morphology of the printed components at the grain boundaries, where there are significantly fewer grain boundary precipitates and dislocations are piled up at the grain boundaries.

[0039] Figure 6 This is a STEM-EDS image of the Al-Zn-Mg-Cu-Sc-Ce-Yb-Zr alloy, showing the presence of the Al3(Sc,Zr) phase, which can refine the alloy's grain size and improve its fluidity, thus enhancing the formability of the novel alloy. Figure 7 Analysis of the fracture morphology in (a) and (b) reveals dimples and cleavage planes. The FCC phase increases the interface and also plays a strengthening role.

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An Al-Zn-Mg-Cu system aluminum alloy dedicated to friction stir welding additive manufacturing, characterized in that, The aluminum alloy material contains the following components in percentage by mass: Zn 5%~11%, Mg 1%~2.5%, Cu 1%~2.2%, Zr 0.1%~1%, Sc 0.1%~1.5%, Ce 0.1~1.2%, Yb 0.1~1.5%, and other contents are Al.

2. The method for preparing an Al-Zn-Mg-Cu series aluminum alloy dedicated to friction stir welding additive manufacturing according to claim 1, characterized in that, Comprise: melting, ingot casting, homogenization heat treatment.

3. The method of claim 2, wherein the Al-Zn-Mg-Cu series aluminum alloy for friction stir welding additive manufacturing is characterized by, The method of the homogenization heat treatment comprises twice temperature rising of the ingot, the first time rising to 400 DEG C, holding for 10 hours; the second time rising to 465 DEG C, holding for 24 hours.

4. A method of producing an additively printed piece from the Al-Zn-Mg-Cu system aluminum alloy dedicated to friction stir welding additive manufacturing according to claim 1, characterized in that, Comprise: stir friction welding additive tool determination, setting substrate preheating temperature, setting stir friction welding additive process parameters, first layer deposition, interlayer circulation additive, start-stop and corner management, interlayer processing and shaping, end and finishing, heat treatment and performance recovery.

5. The method of producing an additively printed piece of claim 4, wherein, The substrate preheating temperature is 700 DEG C~1150 DEG C.

6. The method of making an additively printed piece of claim 4, wherein, The stir friction welding additive process parameters comprise: rotation speed is 280 r / min, forward speed is 110 mm / min, and rod feeding speed is 62 mm / min. 7.The printed piece prepared by the method of any one of claims 4-6.

8. The printed component produced according to the method of claim 7, characterized in that, The yield strength of the printed piece is 500-530 MPa, the tensile strength is 550-590 MPa, and the elongation after fracture is 15-20%.

9. The printed component produced according to the method of claim 7, wherein, The printed piece is crack-free, and the density is 99.99%. 10.The application of the printed piece prepared by the method of any one of claims 7-9 in aerospace aluminum alloy component manufacturing.

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