A high-strength and tough rare earth magnesium alloy component and arc additive manufacturing method

Abstract

A high-strength and tough rare-earth magnesium alloy component and its arc additive manufacturing method are disclosed. While maintaining the existing alloy composition, the method maximizes the release of residual stress in the formed component by controlling the arc additive forming process and subsequent annealing process, while preserving recrystallization distortion energy storage. Based on this, a special solution aging treatment is precisely matched, and the original matrix grains are refined through recrystallization to obtain a special microstructure with grains of 12–20 μm in diameter and no long-period stacking structure (LPSO phase) at grain boundaries. This enables the arc additive manufacturing of high-strength, tough, and non-plastic anisotropic rare-earth magnesium alloy components, solving the challenge of arc additive manufacturing of large-size rare-earth magnesium alloy components.

Description

Technical Field

[0001] This application belongs to the field of additive manufacturing of metallic materials, specifically relating to a high-strength and tough rare earth magnesium alloy component and an electric arc additive manufacturing method. Background Technology

[0002] Rare earth magnesium alloys have the characteristics of low density, high specific strength, good damping and vibration reduction and excellent machinability, and are widely used in aerospace, rail transportation and other fields. Compared with traditional magnesium alloys, rare earth magnesium alloys have good room temperature and high temperature tensile properties, fatigue resistance and creep resistance, and are more suitable for high-performance manufacturing of aerospace components. In rare earth magnesium alloys represented by Mg-Gd-Y system, Gd and Y can play a good role in solid solution strengthening and second phase strengthening. In the subsequent solid solution aging process, fine precipitate phases can be precipitated, which can effectively hinder dislocation slip and improve the mechanical properties of the alloy. At present, in practical engineering applications, large rare earth magnesium alloy components are mainly manufactured by integral casting + CNC machining composite manufacturing process. Its manufacturing has serious limitations, mainly including: (1) The casting of large and complex components has serious macroscopic composition segregation and porosity defects, resulting in inconsistent mechanical properties of different parts of the component and difficulty in controlling the forming quality of the component; (2) During the casting process of large and complex components, the components are prone to deformation and cracking due to the solidification shrinkage of a large amount of melt, resulting in a low component yield. Therefore, the preparation of rare earth magnesium alloy components with high quality consistency and high yield is a prerequisite for their application.

[0003] Arc additive manufacturing, as an emerging digital manufacturing technology, uses a three-dimensional model of a component as a basis. It employs an electric arc to melt metal wire and deposit it layer by layer along a planned path to prepare large, complex, and high-performance blank components. With minimal machining, high-performance components meeting engineering requirements can be produced. However, rare-earth magnesium alloys have high thermal conductivity and rapid heat dissipation, resulting in a small molten pool and unstable droplet transition during arc additive manufacturing. This leads to weak interlayer bonding, easy formation of defects, and reduced mechanical properties of rare-earth magnesium alloy components. A literature search revealed that patent CN 116618792A discloses an arc additive manufacturing method for Mg-Y-Nd-Zr rare-earth magnesium alloy structural components. The components, after arc additive manufacturing, heat preservation, and subsequent heat treatment, exhibit relatively good mechanical properties. However, Mg-Gd rare-earth magnesium alloy components have significantly higher solid solution strengthening and precipitation strengthening capabilities than Mg-Y-Nd-Zr rare-earth magnesium alloys, making the aforementioned method difficult to apply to the arc additive manufacturing of Mg-Gd rare-earth magnesium alloy components. Patent CN117182251A discloses a forming method for a Mg-9.2Gd-3.2Y-2Zn-0.4Zr alloy. This invention uses a liquid nitrogen spray gun to accelerate the cooling of the formed component during forming, thereby obtaining a fine-grained component and improving its mechanical properties. However, this method results in complex arc additive forming operations and makes it difficult to precisely control the component cooling rate, reducing the manufacturing efficiency of arc additive forming. Patent CN117283088A discloses an arc forming process for a Mg-9.2Gd-3.2Y-2Zn-0.4Zr alloy. This invention, by adjusting process parameters, keeps the heat accumulation of the formed component below 246℃, generating a large amount of network second phase Mg5(Gd,Y) at the grain boundaries to improve the component's hardness and compressive properties. However, this invention has relatively narrow forming process parameters, making it difficult to apply to industrial production. To meet the high-quality, high-performance manufacturing requirements of aerospace rare-earth magnesium alloy components, research on high-performance, high-efficiency arc additive forming methods for rare-earth magnesium alloy components is urgently needed to satisfy their engineering application needs. Summary of the Invention

[0004] The technical problem solved by this application is to overcome the shortcomings of the prior art and provide an electric arc additive manufacturing method for high-strength and tough rare earth magnesium alloy components. By controlling the electric arc additive forming process and accurately matching the subsequent heat treatment method, the microstructure and mechanical properties of the formed components are consistent, thereby improving the overall mechanical properties of the components and increasing manufacturing efficiency.

[0005] An arc additive manufacturing method for high-strength and high-toughness rare-earth magnesium alloy components includes the following steps:

[0006] S1: Load the rare earth magnesium alloy wire into the wire feeder;

[0007] S2: After cleaning the magnesium alloy substrate, fix it on the work platform and start the dehumidification equipment to perform dehumidification.

[0008] S3: Import the 3D CAD model of the component into the arc additive manufacturing software for layering and slicing and to define the forming path;

[0009] S4: When the moisture content of the forming chamber is below 50%, the electric arc is activated to melt and deposit the wire into a dense component. After one layer is deposited, the next layer is deposited after a set interval.

[0010] S5: Repeat steps S4 and S5 to continuously deposit and manufacture rare earth magnesium alloy components.

[0011] S6: After deposition is completed, the rare earth magnesium alloy components and substrate are placed in a heat treatment furnace for annealing.

[0012] S7: Separate the annealed rare earth magnesium alloy component from the substrate and cut the rare earth magnesium alloy component off the substrate.

[0013] S8: Place the rare earth magnesium alloy component into a heat treatment furnace for solution aging special heat treatment to obtain the final rare earth magnesium alloy component.

[0014] In step S4, the arc additive manufacturing deposition process parameters are as follows: wire elongation 10-14 mm, argon gas flow rate 25-35 L / min, current 100-120 A, wire feed rate 9-10 m / min, deposition rate 6-8 mm / s, layer thickness 3-4 mm, and overlap ratio 55-60%.

[0015] In step S4, by controlling the process parameters of arc additive forming, the energy density of the rare earth magnesium alloy deposition region is controlled to be 45-55 J / mm, the overlap rate is 55-60%, and the cooling rate at the front edge of the forming molten pool interface is 102-102.5 K / s. Grains with a diameter of 25-35 μm and LPSO aggregate phases with a diameter of 0.1-0.2 μm are prepared at the grain boundaries, which provides driving force for subsequent recrystallization of matrix grains.

[0016] In step S4, the interlayer interval time is 15 to 25 minutes;

[0017] In step S4, the diameter of the rare earth magnesium alloy wire is Φ1.2mm;

[0018] In step S4, the rare earth magnesium alloy wire has the following composition by mass percentage: gadolinium (Gd): 8.0–12.0%, yttrium (Y): 2.5–4.5%, zinc (Zn): 1.5–2.5%, zirconium (Zr): 0.8–1.2%, other individual impurity elements: ≤0.1%, total of other impurity elements: ≤0.2%, and the balance is Mg;

[0019] In step S6, the interval between the completion of rare earth magnesium alloy component forming and the heating in the annealing furnace shall not exceed 4 hours.

[0020] In step S6, the rare earth magnesium alloy component and the substrate are heated to 300-350°C at a rate of 100-120°C / h and held at that temperature for 6-12 hours to eliminate residual stress in the formed component.

[0021] In step S8, the special heat treatment includes solution treatment and aging treatment. Solution treatment includes heating the sample to 525-535℃ at 2-5℃ / min, holding it at that temperature for 2-6 hours, and cooling it to room temperature at a rate not less than 10℃ / s. After the solution treatment is completed, aging treatment is performed. Aging treatment includes heating the sample to 200-250℃ at 2-5℃ / min, holding it at that temperature for 250-300 hours, and cooling it to room temperature at a rate not less than 15℃ / s. Through special heat treatment, the matrix grains can be refined by recrystallization, while avoiding the growth of the original matrix grains and the aggregation of LPSO phase at grain boundaries, which reduces the strength and toughness of the grain boundaries. A special microstructure with grains of 12-20μm in diameter and no LPSO phase at the grain boundaries is obtained.

[0022] This invention proposes an arc additive manufacturing method for high-strength and tough rare-earth magnesium alloy components. The main idea is to obtain grains with a diameter of 25-35 μm and LPSO aggregate phases with a diameter of 0.1-0.2 μm at the grain boundaries by controlling the solidification process of arc additive manufacturing, providing a driving force for subsequent microstructure and property control. On this basis, a special annealing treatment is precisely matched to prevent the formed component from cracking due to stress, while not reducing the distortion energy stored in the subsequent microstructure control. At the same time, a special solution aging treatment is precisely matched to obtain a special microstructure with grains with a diameter of 12-20 μm and no LPSO phase at the grain boundaries, thus realizing the arc additive manufacturing of high-strength and tough rare-earth magnesium alloy components.

[0023] Compared with the prior art, this application has the following beneficial technical effects:

[0024] (1) This invention uses rare earth magnesium alloy wire as raw material and adopts electric arc additive forming technology to directly prepare large-size high-performance components that meet engineering applications. Compared with the existing traditional manufacturing technology of rare earth magnesium alloy, this technology has a shorter manufacturing cycle, lower manufacturing cost, and significantly improved material utilization.

[0025] (2) By using the "arc additive manufacturing process control + special annealing treatment control + precise matching solution treatment control" provided by this invention, a special microstructure with grains of 12-20 μm in diameter and no LPSO phase at grain boundaries is obtained, realizing the arc additive manufacturing of high-strength and tough rare earth magnesium alloy components. Figure 1 (and Table 1).

[0026] (3) This invention achieves the preparation of high-strength and high-toughness rare-earth magnesium alloy components by adjusting "arc additive forming parameters + special annealing parameters + precisely matching solution aging treatment parameters" without changing the composition of existing rare-earth magnesium alloy wires. It is also applicable to the design and use of other rare-earth magnesium alloy components. Figure 2 (and Table 1).

[0027] (4) The “electric arc additive forming process control + special annealing treatment control + precise matching solution treatment control” method provided by the present invention is applicable to the electric arc additive manufacturing of large-size rare earth magnesium alloy components containing LPSO phase with a width ≥1000mm. The component has uniform stress release and uniform microstructure and properties, and is suitable for high-performance integral manufacturing of large-size complex rare earth magnesium alloy components under industrial conditions. Attached Figure Description

[0028] Figure 1 The microstructure of the rare earth magnesium alloy arc additive manufacturing deposited sample obtained in Comparative Example 1 is shown in Figure a. The deposited sample shows coarse equiaxed grains, and Figure b is a magnified view of Figure a, showing the intragranular LPSO phase.

[0029] Figure 2 The microstructure of the magnesium alloy arc additive manufacturing sample after special solution aging in Example 1 is shown in Figure a. The sample exhibits fine equiaxed grains after special solution aging, and Figure b is a magnified view of Figure a, showing the absence of LPSO phase within the grains. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments disclosed in the present invention will be described in further detail below with reference to the accompanying drawings.

[0031] A method for arc additive manufacturing of high-strength and high-toughness rare-earth magnesium alloys specifically includes the following steps:

[0032] S1: Load the rare earth magnesium alloy wire into the wire feeder;

[0033] S2: After cleaning the magnesium alloy substrate, fix it on the work platform and start the dehumidification equipment to perform dehumidification.

[0034] S3: Import the 3D CAD model of the component into the arc additive manufacturing software for layering and slicing and to define the forming path;

[0035] S4: When the moisture content of the forming chamber is below 50%, the electric arc is activated to melt and deposit the wire into a dense component. After one layer is deposited, the next layer is deposited after a set interval. The electric arc additive forming deposition process parameters are: wire elongation 10-14mm, argon gas flow rate 25-35L / min, current 100-120A, wire feed rate 9-10m / min, deposition rate 6-8mm / s, layer thickness 3-4mm, and overlap rate 55-60%. By controlling the electric arc additive forming process parameters, the energy density of the rare earth magnesium alloy deposition area is controlled to be 45-55J / mm, and the cooling rate at the front edge of the molten pool interface is 10. 2 ~10 2.5 K / s, grains with a diameter of 25-35 μm were prepared, and LPSO aggregates with a diameter of 0.1-0.2 μm were formed at the grain boundaries, which provided a driving force for subsequent recrystallization of the matrix grains.

[0036] S5: Repeat steps S4 and S5 to continuously deposit and manufacture rare earth magnesium alloy components.

[0037] S6: After deposition is completed, the rare earth magnesium alloy components and substrates are placed in a heat treatment furnace for annealing. The interval between the completion of rare earth magnesium alloy component forming and the heating in the annealing furnace shall not exceed 4 hours. The rare earth magnesium alloy components and substrates shall be heated to 300-350℃ at a rate of 100-120℃ / h and held for 6-12 hours.

[0038] S7: Separate the annealed rare earth magnesium alloy component from the substrate and cut the rare earth magnesium alloy component off the substrate.

[0039] S8: Place the rare earth magnesium alloy component into a heat treatment furnace for solution aging special heat treatment to obtain the final rare earth magnesium alloy component; the special heat treatment includes solution treatment and aging treatment; the solution treatment includes: heating the sample to 525-535℃ at 2-5℃ / min, holding it at that temperature for 2-6h, and controlling the cooling rate to cool to room temperature at a rate not less than 10℃ / s; after the solution treatment is completed, perform aging treatment; the aging treatment includes: heating the sample to 200-250℃ at 2-5℃ / min, holding it at that temperature for 250-300h, and controlling the cooling rate to cool to room temperature at a rate not less than 15℃ / s.

[0040] The rare earth magnesium alloy wires used in the following examples and comparative examples have the following composition by mass: Gadolinium (Gd): 12.0%, Yttrium (Y): 3.5%, Zinc (Zn): 2.0%, Zirconium (Zr): 1.02%, other individual impurity elements: ≤0.1%, total of other impurity elements: ≤0.2%, and the balance is Mg.

[0041] Example 1

[0042] A method for arc additive manufacturing of high-strength and high-toughness rare-earth magnesium alloy components, specifically including:

[0043] S1: Load the rare earth magnesium alloy wire into the wire feeder;

[0044] S2: After cleaning the magnesium alloy substrate, fix it on the work platform and start the dehumidification equipment to perform dehumidification.

[0045] S3: Import the 3D CAD model of the component into the arc additive manufacturing software for layering and slicing and to define the forming path;

[0046] S4: When the moisture content of the forming chamber is below 50%, the electric arc is activated to melt and deposit the wire into a dense component. After one layer is deposited, the next layer is deposited after a set interval. The electric arc additive forming deposition process parameters are: wire elongation 10mm, argon gas flow rate 25L / min, current 100A, wire feed rate 9m / min, deposition rate 6mm / s, layer thickness 3mm, and overlap rate 55%. By controlling the electric arc additive forming process parameters, the energy density of the rare earth magnesium alloy deposition area is controlled to be 45J / mm², and the cooling rate at the leading edge of the molten pool interface is 10. 2 K / s was used to prepare a rare earth magnesium alloy layer with grains of 25 μm in diameter and LPSO aggregates with grain boundaries of 0.1 μm in diameter, which provides a driving force for subsequent recrystallization of the matrix grains.

[0047] S5: Repeat steps S4 and S5 to continuously deposit and manufacture rare earth magnesium alloy components.

[0048] S6: After deposition is completed, the rare earth magnesium alloy components and substrate are placed in a heat treatment furnace for annealing; the interval between the completion of rare earth magnesium alloy component forming and the heating in the annealing furnace is 2 hours; the rare earth magnesium alloy components and substrate are heated to 300℃ at 120℃ / h and held for 6 hours.

[0049] S7: Separate the annealed rare earth magnesium alloy component from the substrate and cut the rare earth magnesium alloy component off the substrate.

[0050] S8: The rare earth magnesium alloy component is placed in a heat treatment furnace for solution aging special heat treatment to obtain the final rare earth magnesium alloy component; the special heat treatment includes solution treatment and aging treatment; the solution treatment includes: heating the sample to 525℃ at 2℃ / min, holding it at that temperature for 12-16h, and controlling the cooling rate to cool to room temperature at 12℃ / s; after the solution treatment is completed, the aging treatment is performed; the aging treatment includes: heating the sample to 200℃ at 2℃ / min, holding it at that temperature for 250h, and controlling the cooling rate to cool to room temperature at 16℃ / s.

[0051] Example 2

[0052] S1: Load the rare earth magnesium alloy wire into the wire feeder;

[0053] S2: After cleaning the magnesium alloy substrate, fix it on the work platform and start the dehumidification equipment to perform dehumidification.

[0054] S3: Import the 3D CAD model of the component into the arc additive manufacturing software for layering and slicing and to define the forming path;

[0055] S4: When the moisture content of the forming chamber is below 50%, the electric arc is activated to melt and deposit the wire into a dense component. After one layer is deposited, the next layer is deposited after a set interval. The electric arc additive forming deposition process parameters are: wire elongation 12mm, argon gas flow rate 30L / min, current 110A, wire feed rate 9.5m / min, deposition rate 7mm / s, layer thickness 3.5mm, and overlap rate 56%. By controlling the electric arc additive forming process parameters, the energy density of the rare earth magnesium alloy deposition area is controlled to be 55J / mm², and the cooling rate at the leading edge of the molten pool interface is 10... 2.2 K / s, grains with a height of 3.5 mm and a diameter of 29 μm were prepared, and the grain boundaries contained LPSO aggregates with a diameter of 0.15 μm, which provided a driving force for subsequent recrystallization of the matrix grains.

[0056] S5: Repeat steps S4 and S5 to continuously deposit and manufacture rare earth magnesium alloy components.

[0057] S6: After deposition is completed, the rare earth magnesium alloy components and substrate are placed in a heat treatment furnace for annealing; the interval between the completion of rare earth magnesium alloy component forming and the heating in the annealing furnace is 3 hours; the rare earth magnesium alloy components and substrate are heated to 320℃ at 120℃ / h and held for 11 hours.

[0058] S7: Separate the annealed rare earth magnesium alloy component from the substrate and cut the rare earth magnesium alloy component off the substrate.

[0059] S8: The rare earth magnesium alloy component is placed in a heat treatment furnace for solution aging special heat treatment to obtain the final rare earth magnesium alloy component; the special heat treatment includes solution treatment and aging treatment; the solution treatment includes: heating the sample to 530℃ at 3℃ / min, holding it at that temperature for 14h, and controlling the cooling rate to cool to room temperature at 14℃ / s; after the solution treatment is completed, the aging treatment is performed; the aging treatment includes: heating the sample to 220℃ at 4℃ / min, holding it at that temperature for 280h, and controlling the cooling rate to cool to room temperature at 17℃ / s.

[0060] Example 3

[0061] S1: Load the rare earth magnesium alloy wire into the wire feeder;

[0062] S2: After cleaning the magnesium alloy substrate, fix it on the work platform and start the dehumidification equipment to perform dehumidification.

[0063] S3: Import the 3D CAD model of the component into the arc additive manufacturing software for layering and slicing and to define the forming path;

[0064] S4: When the moisture content of the forming chamber is below 50%, the electric arc is activated to melt and deposit the wire into a dense component. After one layer is deposited, the next layer is deposited after a set interval. The electric arc additive forming deposition process parameters are: wire elongation 14mm, argon gas flow rate 35L / min, current 120A, wire feed rate 9-10m / min, deposition rate 8mm / s, layer thickness 4mm, and overlap rate 60%. By controlling the electric arc additive forming process parameters, the energy density of the rare earth magnesium alloy deposition area is controlled to be 50J / mm², and the cooling rate at the front edge of the molten pool interface is 10. 2.5 K / s was used to prepare grains with a height of 4 mm and a diameter of 35 μm, with LPSO aggregates with a diameter of 0.2 μm at the grain boundaries, which provided a driving force for subsequent recrystallization of the matrix grains.

[0065] S5: Repeat steps S4 and S5 to continuously deposit and manufacture rare earth magnesium alloy components.

[0066] S6: After deposition is completed, the rare earth magnesium alloy components and substrate are placed in a heat treatment furnace for annealing; the interval between the completion of rare earth magnesium alloy component forming and the heating in the annealing furnace is 4 hours; the rare earth magnesium alloy components and substrate are heated to 350℃ at 120℃ / h and held for 12 hours.

[0067] S7: Separate the annealed rare earth magnesium alloy component from the substrate and cut the rare earth magnesium alloy component off the substrate.

[0068] S8: The rare earth magnesium alloy component is placed in a heat treatment furnace for solution aging special heat treatment to obtain the final rare earth magnesium alloy component; the special heat treatment includes solution treatment and aging treatment; the solution treatment includes: heating the sample to 535℃ at 5℃ / min, holding it at that temperature for 16h, and controlling the cooling rate to cool to room temperature at 15℃ / s; after the solution treatment is completed, the aging treatment is performed; the aging treatment includes: heating the sample to 250℃ at 5℃ / min, holding it at that temperature for 300h, and controlling the cooling rate to cool to room temperature at 18℃ / s.

[0069] Example 4

[0070] The only difference from Example 1 is that the arc additive manufacturing deposition process parameters are: wire elongation 11 mm, argon gas flow rate 28 L / min, current 108 A, wire feed rate 9.2 m / min, deposition rate 7.0 mm / s, layer thickness 3.4 mm, and overlap rate 59%. By controlling the arc additive manufacturing process parameters, the energy density of the rare earth magnesium alloy deposition region is controlled to be 49 J / mm², and the cooling rate at the molten pool interface front is 10. 2.2K / s, a rare earth magnesium alloy layer with grains of 28.5 μm in diameter and LPSO aggregates of 0.16 μm in diameter at the grain boundaries was prepared, which provides a driving force for subsequent recrystallization of the matrix grains.

[0071] Example 5

[0072] The only difference from Example 1 is that the arc additive manufacturing deposition process parameters are: wire elongation 13.5 mm, argon gas flow rate 32 L / min, current 118 A, wire feed rate 9.8 m / min, deposition rate 7.8 mm / s, layer thickness 3.8 mm, and overlap rate 57%. By controlling the arc additive manufacturing process parameters, the energy density of the rare earth magnesium alloy deposition region is controlled to be 52 J / mm², resulting in a cooling rate of 10 at the molten pool interface front. 2.3 K / s was used to prepare a rare earth magnesium alloy layer with grains of 32 μm in diameter and LPSO aggregates with grain boundaries of 0.18 μm in diameter, which provides a driving force for subsequent recrystallization of the matrix grains.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 1 is that Comparative Example 1 was prepared using the molding parameters of Example 1, and only underwent annealing treatment without subsequent solution treatment and aging. (That is, S1-S7 are the same as in Example 1, but S8 is omitted.)

[0075] Comparative Example 2

[0076] The difference between this comparative example and Example 1 is that Comparative Example 1 was prepared using the molding parameters of Example 1, without annealing, but with subsequent solution aging treatment (i.e., without S6 and S7). This method is highly prone to causing sample cracking, making it difficult to obtain a complete sample.

[0077] Figure 1 To obtain the microstructure of the deposited sample in Comparative Example 1, Figure 2 The microstructure of the rare earth magnesium alloy obtained in Example 1 was tested. The tensile strength Rm, yield strength Rp0.2, and elongation (A%) of the rare earth magnesium alloys of the comparative example and example were tested, and the test results are shown in Table 1.

[0078] like Figure 1 As shown in Table 1, Comparative Example 1 exhibits coarse grains with LPSO phase agglomeration at grain boundaries. The tensile strength and yield strength of the sample are significantly lower than the application requirements, and the sample shows plastic anisotropy in both directions. After adopting the present invention, the tensile strength and elongation of the sample are significantly improved, and the sample shows no plastic anisotropy in both directions, approaching the application requirements. Using the method of the present invention, high-strength and high-toughness rare-earth magnesium alloy arc additive manufacturing components can be directly prepared without changing the composition of existing rare-earth magnesium alloys.

[0079] Table 1. Comparison of strength and toughness of rare earth magnesium alloy components manufactured by arc additive manufacturing, annealing, and special solution treatment.

[0080]

[0081] In step S4, when the arc current is too low (less than 100A), the wire feed rate is too low (less than 9m / min), and the deposition rate is too low (less than 6mm / s), the heat accumulation in the arc additive forming process is too high, which easily leads to the formation of coarse grains, causing cracks in the rare earth magnesium alloy components, making them unsuitable for industrial production. When the arc current is too high (greater than 120A), the wire feed rate is too high (greater than 10m / min), and the deposition rate is too high (greater than 8mm / s), coarse grains and precipitated phase structures are formed, and the grain boundary distortion energy is low, which cannot provide sufficient driving force for subsequent special solid solution aging treatment, and it is impossible to obtain the fine grains and fine grain boundary precipitated phase structures required for high-strength and tough rare earth magnesium alloys.

[0082] In step S6, if the interval between the completion of rare earth magnesium alloy component forming and the heating in the annealing furnace is too long (greater than 4 hours), the residual stress in the component cannot be released in time, which can easily lead to cracking and render the component unsuitable for industrial production. Similarly, if the heating rate of the rare earth magnesium alloy is too low (less than 100℃ / h), the residual stress in the component cannot be released in time, which can easily lead to cracking. If the heating rate of the rare earth magnesium alloy component is too high (greater than 120℃ / h), the residual stress in the component is released too quickly, which can easily lead to cracking. Furthermore, if the holding temperature of the rare earth magnesium alloy component is too low (below 300℃), the residual stress will not be released in time, which can also easily lead to cracking. When the holding temperature of rare earth magnesium alloy components is too high (above 350℃) and the holding time is too long (above 12h), the components are prone to softening, reducing the driving force for subsequent recrystallization. When the recrystallization driving force of the sample is too small, recrystallization cannot occur to refine the grains. When the holding temperature of rare earth magnesium alloy components is too high (above 350℃) and the holding time is too long (above 12h), the recrystallized grains of the sample undergo secondary growth, and the grains are too coarse, which cannot improve the mechanical properties of the sample.

[0083] In step S8, if the solution temperature is too low (below 525℃) and the holding time is too short (below 2h), the recrystallization drive is too small, and recrystallization to refine the grains cannot occur, resulting in tensile properties of the sample that are lower than the requirements for use. If the solution temperature is too high (above 535℃) and the holding time is too long (above 6h), the fine grains and fine grain boundary precipitates in the sample will transform into coarse grains and coarse precipitates, resulting in tensile properties of the sample that are lower than the standard requirements. If the aging temperature is too low (below 200℃) and the holding time is too short (below 250h), the sample cannot obtain fine grains and fine grain boundary precipitates, resulting in tensile properties of the sample that are lower than the standard requirements. If the aging temperature is too high (above 300℃) and the holding time is too long (above 300h), the sample will transform into a coarse grain and coarse grain boundary precipitate structure, resulting in tensile properties of the sample that are lower than the standard requirements.

[0084] The contents not described in detail in this application specification are common knowledge to those skilled in the art.

[0085] The present application has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present application. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and implementation methods of the present application without departing from the spirit and scope of the present application, and all such modifications and improvements fall within the scope of the present application. The scope of protection of the present application is determined by the appended claims.

Claims

1. A method for arc additive manufacturing of high-strength and high-toughness rare-earth magnesium alloy components, characterized in that, include: S1. Fix the substrate on the work platform inside the molding chamber; S2. Dehumidify the forming chamber until the humidity of the forming chamber is below 50%; S3. Deposit a layer of rare earth magnesium alloy wire according to the process parameters of arc additive manufacturing deposition and the forming path. The process parameters of arc additive manufacturing deposition are: wire elongation 10-14mm, argon gas flow rate 25-35L / min, current 100-120A, wire feed rate 9-10m / min, deposition rate 6-8mm / s, layer thickness 3-4mm, and overlap ratio 55-60%. S4. Deposit the next layer at the set interval; S5. Repeat steps S3 and S4 to continuously deposit and manufacture rare earth magnesium alloy components. S6. Place the rare earth magnesium alloy components and substrate into a heat treatment furnace for annealing. S7. Separate the annealed rare earth magnesium alloy component from the substrate and cut the rare earth magnesium alloy component off the substrate. S8: Place the rare earth magnesium alloy component into a heat treatment furnace for special heat treatment to obtain the final rare earth magnesium alloy component.

2. The method for arc additive manufacturing of high-strength and high-toughness rare-earth magnesium alloy components according to claim 1, characterized in that: In S4, the set time is 15 to 25 minutes.

3. The method for arc additive manufacturing of high-strength and high-toughness rare-earth magnesium alloy components according to claim 1, characterized in that: Based on the sum of the mass percentages of each component being 100%, the rare earth magnesium alloy wire includes: gadolinium (Gd): 8.0–12.0%, yttrium (Y): 2.5–4.5%, zinc (Zn): 1.5–2.5%, zirconium (Zr): 0.8–1.2%, and the total of other impurity elements ≤0.2%, with each individual impurity element comprising ≤0.1%, and the balance being Mg.

4. The method for arc additive manufacturing of high-strength and high-toughness rare-earth magnesium alloy components according to claim 1, characterized in that: The rare earth magnesium alloy components manufactured by continuous deposition have grains with a diameter of 25 to 35 μm and grain boundaries containing LPSO aggregates with a diameter of 0.1 to 0.2 μm.

5. The method for arc additive manufacturing of high-strength and high-toughness rare-earth magnesium alloy components according to claim 1, characterized in that: In step S6, the interval between the completion of the rare earth magnesium alloy component forming and the start of heating in the internal heat treatment furnace shall not exceed 4 hours.

6. The method for arc additive manufacturing of high-strength and high-toughness rare-earth magnesium alloy components according to claim 1, characterized in that, In step S6, the annealing process includes: heating to 300-350°C at a rate of 100-120°C / h and holding at that temperature for 6-12 hours.

7. The method for arc additive manufacturing of high-strength and high-toughness rare-earth magnesium alloy components according to claim 1, characterized in that: In S8, the special heat treatment includes solution treatment and aging treatment performed sequentially.

8. The method for arc additive manufacturing of high-strength and high-toughness rare-earth magnesium alloy components according to claim 7, characterized in that, The solution treatment includes: heating the rare earth magnesium alloy component to 525-535°C at a rate of 2-5°C / min, holding it at that temperature for 2-6 hours, and then cooling it to room temperature at a rate of no less than 10°C / s.

9. The method for arc additive manufacturing of high-strength and high-toughness rare-earth magnesium alloy components according to claim 7, characterized in that, The aging treatment includes: heating the sample to 200-250°C at a rate of 2-5°C / min, holding it at that temperature for 250-300 hours, and then cooling it to room temperature at a rate of no less than 15°C / s.

10. A high-strength and high-toughness rare-earth magnesium alloy component, characterized in that, The high-strength and tough rare-earth magnesium alloy component is prepared by an arc additive manufacturing method according to any one of claims 1-9.

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