Spray forming 7xxx-series alloy powder by-product recycling method based on ded additive manufacturing and applications thereof

Abstract

The application discloses a spray forming 7xxx series alloy powder by-product recycling method based on DED additive manufacturing and application thereof, and belongs to the technical field of material preparation, and comprises multi-stage screening, drying treatment, powder mixing, DED laser additive manufacturing and heat treatment of the spray forming 7xxx series aluminum alloy powder by-product; the method can convert the 7xxx series waste powder generated in the spray forming process into a high-value-added powder for additive manufacturing, thereby reducing energy loss and production cost of aluminum powder preparation, reducing environmental pollution of the spray forming aluminum powder by-product, and achieving the advantages of high tensile strength, high elongation and high alloy density. 0.2 .

Description

Technical Field

[0001] This invention relates to a method for recycling and reusing byproducts of spray-formed 7xxx series alloy powders based on DED (laser directed energy deposition) additive manufacturing, and its application. In particular, it relates to a comprehensive utilization method for using powder byproducts generated during spray forming in additive manufacturing, belonging to the field of materials preparation technology. Background Technology

[0002] 7xxx series aluminum alloys possess advantages such as high specific strength, good machinability, and low density, making them widely used as lightweight, high-strength materials in aerospace, automotive, and military fields. 7xxx series aluminum alloys typically have high levels of alloying elements such as Zn, Mg, and Cu. Traditional casting methods for preparing 7xxx series aluminum alloy ingots suffer from significant internal stress and elemental segregation, making it difficult to produce high-Zn-content 7xxx series aluminum alloys. In recent years, spray forming technology has shown significant advantages in producing high-element-content, large-size 7xxx series aluminum alloy ingots. Spray forming technology utilizes high-pressure inert gases such as argon and nitrogen to atomize molten metal droplets into micron-sized fine droplets, which then travel at high speed along the nozzle axis and deposit into a billet before the droplets completely solidify. 7xxx series ingots prepared using this method offer advantages such as high elemental content, fine grains, uniform microstructure, and no significant macroscopic segregation, making it a mainstream technology for preparing highly alloyed, large-size materials. Therefore, the use of spray forming to prepare high-performance 7xxx series aluminum alloys has attracted widespread attention in the aerospace, automotive, and military industries.

[0003] In the process of preparing 7xxx series aluminum alloy ingots using spray forming technology, although most of the atomized metal droplets are deposited on the substrate to form ingots, some metal droplets are deposited outside the substrate, forming micron-sized aluminum powder byproducts, accounting for about 20-30% of the raw material weight. These aluminum powder byproducts not only reduce material utilization and increase production costs, but also easily pollute the environment during storage. When exposed to humid environments and reaching a certain concentration, they are highly susceptible to explosion, posing a safety hazard. Therefore, the recycling and reuse of aluminum powder byproducts during the spray forming of 7xxx series aluminum alloy ingots is an urgent problem to be solved. Currently, the main method for solving the problem of aluminum powder byproducts from spray forming is to achieve aluminum powder recycling and reuse through powder metallurgy methods such as hot pressing sintering and cold isostatic pressing to prepare ingots (CN 111922345 B, CN 113732288 A). However, in industrial production, additional equipment such as hot pressing sintering and cold isostatic pressing is required, and recycling and reuse are further achieved through deformation processing processes such as extrusion and forging after the aluminum powder has been converted into aluminum ingots. This increases the cost of aluminum powder recycling and significantly reduces its recycling value. Therefore, there is an urgent need to find a new process to directly utilize the byproducts of 7xxx series aluminum powder from spray forming, thereby increasing their economic value. This would solve the storage problem of 7xxx series aluminum powder faced by spray forming companies and also generate economic benefits.

[0004] In addition, during the metal spray forming process, approximately 20-30% of atomized powder (i.e., the aforementioned micron-sized aluminum powder byproduct) is often generated. Upon testing, this type of powder exhibits the following characteristics:

[0005] 1. Morphological defects: Sphericity ≤ 0.88 (commercial additive powder requires > 0.9), with a large number of irregularly shaped particles.

[0006] 2. Poor flowability: Hall flow rate ≥ 60.3s / 50g (standard value < 25s / 50g),

[0007] This type of powder is generally reused through hot pressing, cold isostatic pressing, casting, and forging. However, these methods involve complex equipment, complicated processes, and high recycling costs. Furthermore, this powder has large defects, poor sphericity, and poor flowability. In addition, due to its high Zn and Mg content, additives made from this powder have defects such as cracks and pores, making it unsuitable for additive manufacturing. Therefore, the powder produced during spray forming is not suitable for additive manufacturing. Summary of the Invention

[0008] The technical problem this invention aims to solve is to provide, for the first time, a method for recycling and reusing 7xxx series aluminum powder byproducts generated during the spray forming process using laser-directed energy deposition (DED) additive manufacturing. This method utilizes the 7xxx series aluminum powder byproducts generated during spray forming as high-value aluminum powder raw materials for DED additive manufacturing of 7xxx series aluminum alloy materials and components. This method achieves both direct utilization of 7xxx series powder byproducts and significantly reduces the cost of DED additive manufacturing of 7xxx series aluminum powder. The method is simple, economically efficient, and simultaneously meets the requirements for recycling and reusing 7xxx series aluminum powder byproducts from spray forming and low-cost DED additive manufacturing of 7xxx series aluminum powder.

[0009] Meanwhile, this invention provides an application of a method for recycling and reusing byproducts of spray-formed 7xxx series alloy powder based on DED (laser directed energy deposition) additive manufacturing in additive manufacturing.

[0010] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0011] A method for recycling and reusing byproducts of spray-formed 7xxx series alloy powder based on DED additive manufacturing includes screening and drying the powder byproducts, and then preparing bulk materials using laser-directed energy deposition.

[0012] The additive manufacturing of powder by-products is carried out using a laser directional energy deposition printer, and the process parameters are determined by orthogonal experimental design.

[0013] The powder by-products are aluminum alloy powder by-products generated during the spray forming of 7xxx series aluminum alloy billets; the process of preparing bulk materials using 7xxx series aluminum alloy powder by-products is as follows:

[0014] S1. Sieving process: The spray-formed 7xxx series aluminum alloy powder is sieved using a vibrating sieve to obtain aluminum alloy powder with a particle size range of 53-150μm. This powder is spray-formed Al-Zn-Mg-Cu powder.

[0015] The aluminum alloy with a sieve diameter of 53–150 μm has low overall sphericity and a lot of irregularly shaped powder, with a sphericity ≤0.88, a Hall flow rate ≥60.3 s / 50 g, and poor flowability.

[0016] S2. Drying treatment: The spray-formed Al-Zn-Mg-Cu powder obtained in S1 is dried in a vacuum drying oven to remove gas and water. The specific process is to heat the powder at 80-150℃ and keep it at that temperature for 4-10 hours.

[0017] S3. Powder mixing: The dried spray-formed Al-Zn-Mg-Cu powder and nano Ti powder with a particle size range of 5-100nm (vacuum stored before opening) are added to a planetary powder mixer (Integrity) / ball mill at a certain mass fraction ratio to prepare Ti / Al-Zn-Mg-Cu composite powder. The mixing time is at least 2 hours to ensure that the powder is mixed evenly.

[0018] The amount of nano-Ti powder added is 0.5 to 3.5 wt% of the dried spray-formed Al-Zn-Mg-Cu powder;

[0019] S4. Additive manufacturing: The Ti / Al-Zn-Mg-Cu composite powder obtained in S3 is placed into the powder supply cylinder of the DED printer. The DED printer is turned on to print aluminum alloy blocks. The laser power is 1500-2400W, the laser scanning speed is 6-12mm / s, the powder mass flow rate is 4-5g / min, and the overlap rate is 40-80%.

[0020] S5. Heat treatment: The aluminum alloy block printed in S4 is first subjected to solution treatment at a temperature of 475-490℃ for 1-4 hours; then it is subjected to aging treatment at a temperature of 100-140℃ for 11-24 hours.

[0021] Preferably, the spray-formed Al-Zn-Mg-Cu powder is a byproduct of 7055 aluminum alloy powder.

[0022] Preferably, multi-pass samples are prepared on a DED printer using a laser power of 1800W to 2100W, a scanning speed of 10 to 12 mm / s, a powder mass flow rate of 4.62 g / min, and an overlap rate of 60% to 70%.

[0023] Preferably, bulk samples are prepared on a DED printer using a laser power of 2100W, a scanning speed of 12mm / s, a powder mass flow rate of 4.62g / min, and an overlap rate of 65%.

[0024] Preferably, the DED printer is a Raycham LMD8060 DED printer.

[0025] During printing, a high-purity inert gas, one of argon, nitrogen, or helium, is introduced into the forming chamber of the DED printer, with a purity of ≥99.995%.

[0026] The composition and weight percentage of 7xxx series aluminum alloy powder are as follows: Zn 5~13wt.%, Mg 0.5~3wt.%, Cu 0.5~3wt.%, Zr 0.05~0.4wt.%, Fe 0.1~0.5wt.%, Cr 0~0.3wt.%, Mn 0.1~0.5wt.%, Ti 0~0.2wt.%, Si 0.05~0.5wt.%, with the remainder being Al.

[0027] The additive body prepared using the method for recycling and reusing by-products of spray-formed 7xxx series alloy powder based on DED additive manufacturing of the present invention has a tensile strength of 487±23 MPa, an elongation of 5.8±0.1%, a density of at least 99.14%, and a peak hardness of at least 171 HV. 0.2 .

[0028] The additive manufacturing process of this invention is applied in 7xxx series aluminum alloy components in the aerospace, automotive and military industries.

[0029] An additive body prepared by the method of the present invention, wherein the precipitated phase of the additive body is an η′ phase.

[0030] The present invention has the following beneficial effects:

[0031] This invention enables the comprehensive utilization of powder by-products from spray forming, solving the problems faced by enterprises and achieving economic benefits.

[0032] The present invention is simple, flexible and economical in application, with high raw material utilization, low equipment requirements and few steps.

[0033] The alloy material produced by the method of this invention achieves a maximum tensile strength of 487±23 MPa and an elongation of 5.8±0.1%. The alloy has a density of at least 99.14%, is free of cracks and defects, further eliminates irregular pores, and has a peak hardness of at least 171 HV. 0.2 .

[0034] This invention provides a method for recycling and reusing byproducts of spray-formed 7xxx series alloy powder based on DED additive manufacturing, and its application. The method includes multi-stage sieving, drying, mixing, DED laser additive manufacturing, and heat treatment of the spray-formed 7xxx series aluminum alloy powder byproducts. The powder byproducts mainly originate from additional powder byproducts generated during the preparation of spray-formed 7xxx series aluminum alloy blanks. The DED additive manufacturing method uses coaxial powder feeding via laser-directed energy deposition to prepare the spray-formed 7xxx series aluminum alloy powder into an alloy, thereby achieving the recycling and reuse of the powder byproducts. This invention transforms the 7xxx series waste powder generated during spray forming into high-value-added powder for additive manufacturing, reducing energy consumption and production costs in aluminum powder preparation, and minimizing environmental pollution from spray-formed aluminum powder byproducts. The alloy bulk prepared using this method achieves a tensile strength of 487±23 MPa and an elongation of 5.8±0.1%, comparable to the performance of 7055 aluminum alloy manufactured using laser-directed energy deposition additive manufacturing with gas atomization powder preparation. The alloy obtained by this invention has a density of at least 99.14% and a peak hardness of at least 171 HV after aging. 0.2 . Attached Figure Description

[0035] Figure 1 The morphology of the sprayed powder of the present invention (particle size after sieving 53-150μm);

[0036] Figure 2 This is a metallographic diagram of the alloy under the same parameters as in this invention;

[0037] Figure 3 This is the aging hardness curve of the present invention;

[0038] Figure 4 It is the heat-treated alloy strengthening phase of this invention. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to specific embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0040] Example 1

[0041] A method for recycling and reusing byproducts of spray-formed 7xxx series alloy powder based on DED additive manufacturing includes the following steps:

[0042] S1. Sieving process: The spray-formed 7xxx series aluminum alloy powder is sieved using a vibrating sieve to obtain aluminum alloy powder with a particle size range of 53-150μm. This powder is spray-formed Al-Zn-Mg-Cu powder.

[0043] like Figure 1As shown, the aluminum alloy with a sieve diameter of 53–150 μm has low overall sphericity and a large amount of irregularly shaped powder, with a sphericity of 0.88, a Hall flow rate of 60.3 s / 50 g, and poor flowability.

[0044] S2. Drying treatment: The spray-formed Al-Zn-Mg-Cu powder obtained in S1 is dried in a vacuum drying oven to remove gas and water. The specific process is to heat at 100℃ and hold for 6 hours.

[0045] S3. Powder mixing: The dried spray-formed Al-Zn-Mg-Cu powder and nano Ti powder with a particle size range of 5-100nm (vacuum-preserved before opening) are added to a planetary powder mixer (Integrity) at a certain mass fraction ratio to prepare Ti / Al-Zn-Mg-Cu composite powder. The mixing time is 2h to ensure uniform powder mixing.

[0046] The amount of nano-Ti powder added is 1.8 wt% of the dried spray-formed Al-Zn-Mg-Cu powder;

[0047] S4. Additive Manufacturing: Place the Ti / Al-Zn-Mg-Cu composite powder obtained in S3 into the powder supply cylinder of the DED printer, turn on the DED printer, and print an aluminum alloy block. Printing parameters: laser power 2100W, scanning speed 720mm / min, powder mass flow rate 4.62g / min, overlap rate 65%.

[0048] S5. Heat treatment: The aluminum alloy block printed in S4 is first subjected to solution treatment at a temperature of 490℃ for 1 hour; then it is subjected to aging treatment at a temperature of 120℃ for 24 hours.

[0049] The composition and weight percentage of 7xxx series aluminum alloy powder are as follows: Zn 10wt.%, Mg 2wt.%, Cu 1wt.%, Zr 0.2wt.%, Fe 0.3wt.%, Cr 0.2wt.%, Mn 0.3wt.%, Si 0.3wt.%, with the remainder being Al.

[0050] This embodiment describes the application of a method for recycling and reusing byproducts of spray-formed 7xxx series alloy powder based on DED (laser directed energy deposition) additive manufacturing in additive manufacturing.

[0051] The additive body prepared using a method for recycling and reusing byproducts of spray-formed 7xxx series alloy powder based on DED (laser directed energy deposition) additive manufacturing in this embodiment.

[0052] The additive manufacturing process described in this embodiment is applied to 7xxx series aluminum alloy components in the aerospace, automotive, and military industries.

[0053] An additive body is prepared by the method of this embodiment.

[0054] This embodiment adds nano-Ti, as shown in the metallographic image (e.g. Figure 2 As can be seen from (b), defects are significantly reduced, and the defects are basically small, regular pores. Generally, pores are unavoidable in additive manufacturing processes due to the volatilization of Zn and Mg, as well as the entrainment of inert gases. However, in this embodiment, the addition of nano-Ti further eliminates irregular pores, and the alloy density is significantly increased to 99.14%.

[0055] The mechanical properties of the Al-Zn-Mg-Cu+Ti alloy in this embodiment are as follows: tensile strength and elongation reach 487 MPa and 5.8%, respectively. The basic properties are comparable to those of cast aluminum alloys, meaning that the alloy in this embodiment combines the advantages of high Zn content with performance comparable to forged aluminum alloys. Reasons for this analysis: Figure 4 As shown in Figure a, the precipitated phase formed in the Al-Zn-Mg-Cu alloy (Comparative Example 2) after T6 heat treatment is an η phase with a hexagonal C14 structure. In contrast, as shown in Figure a... Figure 4 As shown in b, the precipitated phase formed in the Al-Zn-Mg-Cu-Ti alloy (in this embodiment) after T6 heat treatment is a typical η′ phase, whose structure consists of orthorhombic units (O-units) and rhombic units (R-units). This result confirms that the addition of Ti can suppress the transformation of the η′ phase to its equilibrium phase (η phase), thereby having a beneficial effect on the mechanical properties of the alloy. The peak hardness of the Al-Zn-Mg-Cu+Ti alloy increased to 171 HV after 24 hours of aging. 0.2 .

[0056] Example 2

[0057] A method for recycling and reusing byproducts of spray-formed 7xxx series alloy powder based on DED additive manufacturing includes the following steps:

[0058] S1. Sieving process: The spray-formed 7xxx series aluminum alloy powder is sieved using a vibrating sieve to obtain aluminum alloy powder with a particle size range of 53-150μm. This powder is spray-formed Al-Zn-Mg-Cu powder.

[0059] The aluminum alloy with a sieve diameter of 53–150 μm has low overall sphericity and a lot of irregularly shaped powder. The sphericity is 0.78, the Hall flow rate is 70 s / 50 g, and the flowability is poor.

[0060] S2. Drying treatment: The spray-formed Al-Zn-Mg-Cu powder obtained in S1 is dried in a vacuum drying oven to remove gas and water. The specific process is to heat the powder at 80℃ and keep it at that temperature for 4 hours.

[0061] S3. Powder mixing: The dried spray-formed Al-Zn-Mg-Cu powder and nano Ti powder with a particle size range of 5-100nm (vacuum-preserved before opening) are added to a planetary powder mixer (Integrity) at a certain mass fraction ratio to prepare Ti / Al-Zn-Mg-Cu composite powder. The mixing time is 4h to ensure uniform powder mixing.

[0062] The amount of nano-Ti powder added is 0.5 wt% of the dried spray-formed Al-Zn-Mg-Cu powder;

[0063] S4. Additive manufacturing: The Ti / Al-Zn-Mg-Cu composite powder obtained in S3 is placed into the powder supply cylinder of the DED printer. The DED printer is turned on to print an aluminum alloy block. The laser power is 1500W, the laser scanning speed is 6mm / s, the powder mass flow rate is 4g / min, and the overlap rate is 40%.

[0064] S5. Heat treatment: The aluminum alloy block printed in S4 is first subjected to solution treatment at a temperature of 475℃ for 4 hours; then it is subjected to aging treatment at a temperature of 100℃ for 11 hours.

[0065] The composition and weight percentage of 7xxx series aluminum alloy powder are as follows: Zn 5wt.%, Mg 0.5wt.%, Cu 0.5wt.%, Zr 0.05wt.%, Fe 0.1wt.%, Mn 0.1wt.%, Ti 0.2wt.%, Si 0.05wt.%, with the remainder being Al.

[0066] This embodiment describes the application of a method for recycling and reusing byproducts of spray-formed 7xxx series alloy powder based on DED (laser directed energy deposition) additive manufacturing in additive manufacturing.

[0067] The additive body prepared using a method for recycling and reusing byproducts of spray-formed 7xxx series alloy powder based on DED (laser directed energy deposition) additive manufacturing in this embodiment.

[0068] The additive manufacturing process described in this embodiment is applied to 7xxx series aluminum alloy components in the aerospace, automotive, and military industries.

[0069] An additive body is prepared by the method of this embodiment.

[0070] The mechanical properties of the Al-Zn-Mg-Cu+Ti alloy in this embodiment are as follows: tensile strength and elongation reach 464 MPa and 5.7%, respectively. The density of the Al-Zn-Mg-Cu+Ti alloy is significantly improved to 99.25%, and the peak hardness after aging increases to 180 HV. 0.2 .

[0071] Example 3

[0072] A method for recycling and reusing byproducts of spray-formed 7xxx series alloy powder based on DED additive manufacturing includes the following steps:

[0073] S1. Sieving process: The spray-formed 7xxx series aluminum alloy powder is sieved using a vibrating sieve to obtain aluminum alloy powder with a particle size range of 53-150μm. This powder is spray-formed Al-Zn-Mg-Cu powder.

[0074] The aluminum alloy with a sieve diameter of 53–150 μm has low overall sphericity and a lot of irregularly shaped powder. The sphericity is 0.80, the Hall flow rate is 65 s / 50 g, and the flowability is poor.

[0075] S2. Drying treatment: The spray-formed Al-Zn-Mg-Cu powder obtained in S1 is dried in a vacuum drying oven to remove gas and water. The specific process is to heat the powder at 150℃ and keep it at that temperature for 10 hours.

[0076] S3. Powder mixing: The dried spray-formed Al-Zn-Mg-Cu powder and nano Ti powder (vacuum stored before opening) are added to a ball mill at a certain mass fraction ratio to prepare Ti / Al-Zn-Mg-Cu composite powder. The mixing time is 7h to ensure that the powder is mixed evenly.

[0077] The amount of nano-Ti powder added is 3.5 wt% of the dried spray-formed Al-Zn-Mg-Cu powder;

[0078] S4. Additive manufacturing: The Ti / Al-Zn-Mg-Cu composite powder obtained in S3 is placed into the powder supply cylinder of the DED printer. The DED printer is turned on to print an aluminum alloy block. The laser power is 2400W, the laser scanning speed is 10mm / s, the powder mass flow rate is 5g / min, and the overlap rate is 80%.

[0079] S5. Heat treatment: The aluminum alloy block printed in S4 is first subjected to solution treatment at a temperature of 485℃ for 2 hours; then it is subjected to aging treatment at a temperature of 140℃ for 20 hours.

[0080] The composition and weight percentage of 7xxx series aluminum alloy powder are as follows: Zn 13wt.%, Mg 3wt.%, Cu 3wt.%, Zr 0.4wt.%, Fe 0.5wt.%, Cr 0.3wt.%, Mn 0.5wt.%, Ti 0.1wt.%, Si 0.5wt.%, with the remainder being Al.

[0081] This embodiment describes the application of a method for recycling and reusing byproducts of spray-formed 7xxx series alloy powder based on DED (laser directed energy deposition) additive manufacturing in additive manufacturing.

[0082] The additive body prepared using a method for recycling and reusing byproducts of spray-formed 7xxx series alloy powder based on DED (laser directed energy deposition) additive manufacturing in this embodiment.

[0083] The additive manufacturing process described in this embodiment is applied to 7xxx series aluminum alloy components in the aerospace, automotive, and military industries.

[0084] An additive body is prepared by the method of this embodiment.

[0085] The mechanical properties of the Al-Zn-Mg-Cu+Ti alloy in this embodiment are as follows: tensile strength and elongation reach 510 MPa and 5.9%, respectively. The density of the Al-Zn-Mg-Cu+Ti alloy is significantly improved to 99.54%, and the peak hardness after aging increases to 189 HV. 0.2 .

[0086] Example 4

[0087] The only difference between this embodiment and Embodiment 1 is the printing parameters: 1800W laser power, 11mm / s scanning speed, and 60% overlap rate.

[0088] The mechanical properties of the Al-Zn-Mg-Cu+Ti alloy in this embodiment are as follows: tensile strength and elongation reach 479 MPa and 5.8%, respectively. The density of the Al-Zn-Mg-Cu+Ti alloy is significantly improved to 99.33%, and the peak hardness after aging increases to 172 HV. 0.2 .

[0089] Example 5

[0090] The only difference between this embodiment and Embodiment 1 is the 70% overlap rate.

[0091] The mechanical properties of the Al-Zn-Mg-Cu+Ti alloy in this embodiment are as follows: tensile strength and elongation reach 499 MPa and 5.8%, respectively. The density of the Al-Zn-Mg-Cu+Ti alloy is significantly improved to 99.48%, and the peak hardness after aging increases to 175 HV. 0.2 .

[0092] Comparative Example 1

[0093] The only difference between this comparative example and Example 1 is that no nano-Ti powder was added and no S5 heat treatment operation was performed.

[0094] For spray-formed Al-Zn-Mg-Cu powder, suitable printing parameters were selected through extensive orthogonal experiments (printing parameters: laser power 2100W, scanning speed 720mm / min, powder mass flow rate 4.62g / min, overlap rate 65%). Metallographic images of the obtained printed aluminum alloy blocks (e.g.) Figure 2 As shown in figure a), many irregular pores can still be observed. The tensile strength of the alloy is 272 MPa, and the elongation is only 2.8%. The Al-Zn-Mg-Cu alloy, after parameter optimization, eliminated crack defects but still exhibits high-density and irregularly shaped pores. The alloy density is only 97.57%.

[0095] Comparative Example 2

[0096] The only difference between this comparative example and Example 1 is that no nano-Ti powder was added, and the S5 heat treatment operation was performed.

[0097] After optimized heat treatment (490℃ / 1h + 120℃ / 24h), the tensile strength of the Al-Zn-Mg-Cu alloy is 350MPa and the elongation is 1.9%.

[0098] like Figure 4 As shown in Figure a, the heat-treated alloy strengthening phase is the η phase with a hexagonal C14 structure in the Al-Zn-Mg-Cu alloy treated with T6 heat treatment. The measured lattice parameters are a = 0.511 nm and c = 0.863 nm. This structure is composed of alternating close-packed rhombic units (R-unit) and 180° rotated R' units (R'-unit).

[0099] Comparative Example 3

[0100] The only difference between this comparative example and comparative example 2 is that the heat treatment (490℃ / 1h+120℃ / 24h) in comparative example 2 is replaced with heat treatment (470℃ / 1h+120℃ / 24h).

[0101] The age hardening behavior of Al-Zn-Mg-Cu alloy at different solution temperatures (470℃ and 490℃) was studied:

[0102] Solution treatment temperature has a significant impact on the age-hardening behavior of alloys. For example... Figure 3 As shown in Figure a, for the Al-Zn-Mg-Cu alloy, the aged hardness value at a solution temperature of 490℃ is significantly higher than that at a solution temperature of 470℃. The Al-Zn-Mg-Cu alloy reaches its peak hardness after aging at 120℃ for 24 hours, and the peak hardness increases to 149 HV after 24 hours of aging. 0.2 Furthermore, the hardness tends to stabilize in the later stages of aging.

[0103] Comparative Example 4

[0104] The only difference between this comparative example and Example 1 is that the heat treatment (490℃ / 1h+120℃ / 24h) in Example 1 is replaced with heat treatment (470℃ / 1h+120℃ / 24h).

[0105] The age hardening behavior of Al-Zn-Mg-Cu+Ti alloy at different solution temperatures (470℃ and 490℃) was investigated.

[0106] Solution treatment temperature has a significant impact on the age-hardening behavior of alloys. For example... Figure 3 As shown in b, for the Al-Zn-Mg-Cu+Ti alloy, the aged hardness value at a solution temperature of 490℃ is significantly higher than that at a solution temperature of 470℃. The Al-Zn-Mg-Cu+Ti alloy, after solution treatment at 490℃ and aging at 120℃ for 24 hours, reached its peak hardness of 171 HV. 0.2 Furthermore, the hardness tends to stabilize in the later stages of aging, while the Al-Zn-Mg-Cu+Ti alloy, after solution treatment at 470℃ and aging at 120℃ for 24 hours, exhibits a peak hardness of 155 HV. 0.2 Because the precipitated phase in this comparative alloy is the η phase, the solution temperature of 470℃ cannot suppress the transformation of the η′ phase to its equilibrium phase (η phase), thus reducing the alloy's hardness, while the tensile strength and elongation reach 421 MPa and 3.5%, respectively.

[0107] Comparative Example 5

[0108] The only difference between this comparative example and Example 1 is that:

[0109] The amount of nano-Ti powder added was 0.4 wt%.

[0110] In this comparative example, the amount of nano-Ti powder added was relatively small, resulting in the η phase as the precipitated phase in the final alloy. The tensile strength of the Al-Zn-Mg-Cu+0.4%Ti alloy was 357 MPa, the elongation was 2.0%, the alloy density was only 97.89%, and the peak hardness after aging was 155 HV. 0.2 .

[0111] Comparative Example 6

[0112] The only difference between this comparative example and Example 1 is that:

[0113] The amount of nano-Ti powder added was 3.8 wt%.

[0114] In this comparative example, the amount of nano-Ti powder added was relatively high, and the final alloy precipitated phase was also the η phase. The tensile strength of the Al-Zn-Mg-Cu+3.8%Ti alloy was 365 MPa, the elongation was 2.5%, the alloy density was 98.09%, and the peak hardness after aging was 153 HV. 0.2 .

[0115] Therefore, it can be seen that in this invention, the amount of nano-Ti powder added too much or too little, as well as the appropriate solution temperature, will affect the mechanical properties of the alloy. Only by combining the specific proportion of nano-Ti powder added with the heat treatment process in this invention can the material achieve efficient reuse of waste powder and additive manufacturing.

[0116] It should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof in the above description of exemplary embodiments of the invention. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in fewer than all the features of the foregoingly disclosed embodiments. Therefore, the claims, following the detailed description, are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0117] Although the invention has been described with reference to a limited number of embodiments, those skilled in the art will understand from the foregoing description that other embodiments are conceivable within the scope of the invention described herein. Furthermore, it should be noted that the language used in this specification has been chosen primarily for readability and instructional purposes, and not for the purpose of interpreting or limiting the subject matter of the invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the invention is illustrative and not restrictive, and the scope of the invention is defined by the appended claims.

[0118] 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. A method for recycling of DED additive manufacturing based spray forming 7xxx series aluminum alloy powder by-product, characterized in that, Comprising the following steps: S1, screening treatment: screening treatment is carried out on the spray forming 7xxx series aluminum alloy powder, and aluminum alloy powder with a particle size range of 53-150 μm is obtained, wherein the powder is spray forming Al-Zn-Mg-Cu powder; S2, drying treatment: the spray forming Al-Zn-Mg-Cu powder obtained in S1 is subjected to drying treatment; S3, powder mixing: the spray forming Al-Zn-Mg-Cu powder after drying and nano-Ti powder with a particle size range of 5-100 nm are added into a powder mixing instrument or a ball mill instrument at a certain mass fraction ratio to prepare a composite powder; The addition amount of nano-Ti powder is 0.5-3.5 wt% of the spray forming Al-Zn-Mg-Cu powder after drying; S4, additive manufacturing: printing an aluminum alloy block, the laser power is 1500-2400 W, the laser scanning speed is 6-12 mm / s, the powder mass flow rate is 4-5 g / min, and the overlap rate is 40-80%; S5, heat treatment: the aluminum alloy block printed in S4 is first subjected to solution treatment at a solution temperature of 475-490 ℃ and a solution time of 1-4 h, and then subjected to aging treatment at an aging temperature of 100-140 ℃ and an aging time of 11-24 h.

2. The method of claim 1, wherein, In S1, the aluminum alloy after screening with a particle size of 53-150 μm has a sphericity of ≤0.88 and a Hall flow rate of ≥60.3 s / 50 g.

3. The method of claim 1, wherein, In S2, the drying is vacuum drying, the heating temperature is 80-150 ℃, and the holding time is 4-10 h.

4. The method of claim 1, wherein, In S3, the nano-Ti powder is stored in vacuum before being opened; the mixing time is at least 2 h to ensure uniform mixing of the powder.

5. The method of claim 1, wherein, In S4, the printing parameters are: a laser power of 1800-2100 W, a scanning speed of 10-12 mm / s, a powder mass flow rate of 4.62 g / min, and an overlap rate of 60%-70%.

6. The method of claim 1, wherein, In S4, the printing parameters are: a laser power of 2100 W, a scanning speed of 12 mm / s, a powder mass flow rate of 4.62 g / min, and an overlap rate of 65%.

7. The method of claim 1, wherein, The spray forming 7xxx series aluminum alloy powder comprises the following components and wt%: Zn 5-13 wt.%, Mg 0.5-3 wt.%, Cu 0.5-3 wt.%, Zr 0.05-0.4 wt.%, Fe 0.1-0.5 wt.%, Cr 0-0.3 wt.%, Mn 0.1-0.5 wt.%, Ti 0-0.2 wt.%, Si 0.05-0.5 wt.%, and the remainder is Al.

8. The additive body obtained by the method according to any one of claims 1 to 7, characterized in that Tensile strength of 487 ± 23 MPa, elongation of 5.8 ± 0.1 %, density of at least 99.14 %, peak hardness of at least 171 HV 0.2 .

9. Application of the additive body according to claim 8 in 7xxx series aluminum alloy components in the fields of aerospace, automobile and military industry.

10. An additive body, characterized by The additive body is prepared by the method according to any one of claims 1-7, and the precipitated phase of the additive body is η' phase.

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