Additive manufacturing method of AlN magnesium-based alloy

Abstract

The invention relates to an additive manufacturing method of an AlN magnesium-based alloy. The additive manufacturing method comprises the following steps that S1, metal powder is prepared, and the metal powder comprises the following elements in parts by weight: 88.96 to 93.72 parts of Mg, 2.3 to 3.4 parts of Li, 2.1 to 3.1 parts of Nd, 0.5 to 0.7 part of Zr, 2.8 to 3.2 parts of Zn and 4.6 to 8.4 parts of AlN; s2, printing forming is conducted, specifically, part modeling is conducted firstly, then metal powder is sprayed to a printing platform according to a design path, then laser scanning is conducted on the path, the metal powder is melted and then solidified, a first layer of the part is constructed, the actions are repeated, and part construction is completed layer by layer; s3, solution treatment is conducted, specifically, the part is heated to 350-390 DEG C, heat preservation is conducted, then the part is heated to 525-535 DEG C, and heat preservation is conducted; and S4, aging treatment is conducted, specifically, the part is heated to 280-320 DEG C, and heat preservation is conducted. The method has the advantages that high-temperature casting is not needed, the defects of overburning, cavitation erosion and the like of the part are avoided, and the forming rate and the forming quality of the part are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of magnesium-based alloy manufacturing technology, and in particular to an additive manufacturing method for AlN magnesium-based alloys. Background Technology

[0002] Magnesium-based alloys are metallic materials with low density and excellent specific strength and specific hardness. Compared to steel, magnesium-based alloys produce parts of the same type with lower weight, making them widely used in aerospace manufacturing, shipbuilding, and chemical container manufacturing.

[0003] Currently, magnesium-based alloys are mainly formed by melting, but the requirements for the melting temperature window are extremely strict. If the temperature is too low, the molten raw material will not have enough fluidity, which will affect the uniformity of the alloy structure and increase the impurity content in the alloy. If the temperature is too high, it will easily lead to overheating of the alloy structure and affect the quality of the alloy.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention discloses an additive manufacturing method for AlN magnesium-based alloys.

[0006] An additive manufacturing method for AlN magnesium-based alloys includes the following steps: Step S1: Preparation of metal powder. The metal powder includes the following elements by weight: Mg, 88.96~93.72 parts; Li, 2.3~3.4 parts; Nd, 2.1~3.1 parts; Zr, 0.5~0.7 parts; Zn, 2.8~3.2 parts; AlN, 4.6~8.4 parts. Step S2: Printing and molding. First, model the part. Then, spray the metal powder onto the printing platform according to the design path. Then, scan the path with a laser. After the metal powder melts and solidifies, the first layer of the part is built. Repeat the above actions to complete the part building layer by layer. Step S3: Solution treatment, heat the part to 350~390℃ and hold, then heat to 525~535℃ and hold. Step S4: Aging treatment, heating the parts to 280~320℃ and holding them at that temperature.

[0007] Furthermore, in step S2, the power range of the laser is 60~100W.

[0008] Furthermore, in step S2, the laser scanning speed is 600~1000mm / min, and the laser scanning interval is 0.1~0.4mm.

[0009] Furthermore, in step S2, the thickness of a single layer is 0.5~0.8mm.

[0010] Furthermore, in step S2, helium and argon are used as protective gases.

[0011] Furthermore, in step S3, the heat preservation time at 350~390℃ ranges from 1 to 2 hours.

[0012] Furthermore, in step S3, the heat preservation time at 525~535℃ ranges from 1.5 to 2.5 hours.

[0013] Furthermore, in step S3, the heating rate is 40~60℃ / h.

[0014] Furthermore, in step S4, the heat preservation time ranges from 13 to 17 hours during the 280~320℃ stage.

[0015] Advantages of this invention: 1. By optimizing the magnesium-based alloy formula and using a suitable additive manufacturing method to manufacture parts, compared with traditional melting and casting, the problem of uneven crystal structure caused by uneven element distribution is avoided, the uniformity of crystal structure is improved, which is conducive to the optimization of internal stress distribution, improves the comprehensive mechanical properties of parts, and eliminates the need for high-temperature casting, avoiding defects such as overheating and cavitation in parts, and greatly improving the forming rate and forming quality of parts.

[0016] 2. In the formulation of magnesium alloys, Nd and Mg can form high-melting-point compounds, which improve the thermal stability of the microstructure. When Nd precipitates at the grain boundaries, it can hinder grain boundary slip and improve the stability of the crystal structure. Zr forms a dense composite solid solution with Nd and Zn, which hinders dislocation movement and improves the strength of the alloy. AlN serves as the microstructure framework of magnesium alloys and has good strength.

[0017] 3. Strictly control the laser power range, scanning speed, and scanning spacing to control the energy received by the metal powder per unit area. Because magnesium-based alloys have a low vaporization point, excessive energy will cause local high temperature and lead to microstructure vaporization. Insufficient energy will result in poor fluidity of the molten metal powder, affecting the uniformity of the microstructure. Therefore, controlling the relevant parameters ensures that the metal powder is in a fully molten state, thereby forming a stable and uniform molten zone along the laser scanning path.

[0018] 4. The solid solubility of elements such as Nd, Zn, and Li in α-Mg (hexagonal close-packed structure) and β-Li (body-centered cubic structure) increases significantly with increasing temperature. As the temperature rises to the first solution temperature, the original crystalline phases of elements other than Mg dissolve. Sufficient holding time is given to allow heat to be transferred to the core of the part, control the internal and external temperature gradient, and then heat to the complete solution temperature to ensure that the remaining solid solution dissolves and gradually forms a supersaturated solid solution.

[0019] 5. During the aging process, the supersaturated solid solution gradually decomposes, eventually precipitating a dispersed strengthening phase, which further enhances the strength of the tissue. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the steps of an additive manufacturing method for AlN magnesium-based alloys.

[0021] Figure 2 This is a metallographic image of Example 1.

[0022] Figure 3 This is a metallographic image of Example 2.

[0023] Figure 4 Metallographic examination image of Example 3 Detailed Implementation

[0024] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0025] Example 1: An additive manufacturing method for AlN magnesium-based alloys, such as Figure 1 As shown, it includes the following steps: Step S1: Preparation of metal powder. The metal powder includes the following elements by weight: Mg, 90.11 parts, Li, 2.5 parts, Nd, 2.1 parts, Zr, 0.5 parts, Zn, 3.0 parts, and AlN, 4.6 parts.

[0026] Step S2, Printing and Molding: First, the part is modeled. Helium and argon (98% purity) are used as protective gases to prevent oxidation of the metal powder during molding. Then, the metal powder is sprayed onto the printing platform according to the designed path. A laser scans the path, melting and solidifying the metal powder to build the first layer of the part. This process is repeated layer by layer to complete the part construction. The laser power range is 60W, the laser scanning speed is 600mm / min, the laser scanning interval is 0.1mm, and the thickness of each layer is 0.5mm. Step S3: Solution treatment. The part is heated to 350°C and held for 1 hour, then heated at 40°C / hour, and then heated to 525°C and held for 1.5 hours.

[0027] Step S4: Aging treatment. The parts are heated to 280℃ and held for 13 hours. Finally, samples are taken for testing.

[0028] Example 2: An additive manufacturing method for AlN magnesium-based alloys, such as Figure 1 As shown, it includes the following steps: Step S1: Preparation of metal powder. The metal powder includes the following elements by weight: Mg, 91.76 parts; Li, 2.8 parts; Nd, 2.9 parts; Zr, 0.6 parts; Zn, 3.1 parts; AlN, 6.2 parts.

[0029] Step S2, Printing and Molding: First, the part is modeled. Helium and argon (98% purity) are used as protective gases to prevent oxidation of the metal powder during molding. Then, the metal powder is sprayed onto the printing platform according to the designed path. A laser scans the path, melting and solidifying the metal powder to build the first layer of the part. This process is repeated layer by layer to complete the part construction. The laser power is 80W, the scanning speed is 800mm / min, the scanning interval is 0.2mm, and the thickness of each layer is 0.5mm.

[0030] Step S3: Solution treatment. The part is heated to 370℃ and held for 1 hour, then heated at 50℃ / h, and then held at 535℃ for 1.5 hours.

[0031] Step S4: Aging treatment. The parts are heated to 300℃ and held for 15 hours. Finally, samples are taken for testing.

[0032] Example 3: An additive manufacturing method for AlN magnesium-based alloys, such as Figure 1 As shown, it includes the following steps: Step S1: Preparation of metal powder. The metal powder includes the following elements by weight: Mg, 93.70 parts; Li, 3.4 parts; Nd, 3.0 parts; Zr, 0.7 parts; Zn, 3.2 parts; AlN, 8.1 parts.

[0033] Step S2, Printing and Molding: First, the part is modeled. Helium and argon (98% purity) are used as protective gases to prevent oxidation of the metal powder during molding. Then, the metal powder is sprayed onto the printing platform according to the designed path. A laser scans the path, melting and solidifying the metal powder to build the first layer of the part. This process is repeated layer by layer to complete the part construction. The laser power is 100W, the scanning speed is 1000mm / min, the scanning interval is 0.4mm, and the thickness of each layer is 0.8mm.

[0034] Step S3: Solution treatment. The part is heated to 390℃ and held for 2 hours. The temperature is increased at 60℃ / h, and then heated to 535℃ and held for 2.5 hours.

[0035] Step S4: Aging treatment. The parts are heated to 320℃ and held for 15 hours. Finally, samples are taken for testing.

[0036] Comprehensive product performance testing: Samples: Products from Examples 1-3.

[0037] The inspection results are shown in Table 1.

[0038] Table 1 project Tensile strength (MPa) Yield strength (MPa) Elongation (%) Elastic modulus (GPa) Example 1 305 277 13% 61 Example 2 297 289 11% 60 Example 3 301 264 13% 60 standard ≥220 ≥200 ≥5 ≥45 in conclusion: Tensile strength: The samples in Examples 1-3 were nearly 80 MPa higher than the standard.

[0039] Yield strength: The samples in Examples 1-3 were nearly 60 MPa higher than the standard.

[0040] Elongation: The samples in Examples 1-3 were nearly 6% higher than the standard.

[0041] Elastic modulus: The samples of Examples 1-3 were nearly 15 GPa higher than the standard.

[0042] Metallographic testing of products: Example 1: As Figure 2 As shown, the grain size is grade 5, with no impurity crystal structure and no microcracks.

[0043] Example 2: As Figure 2 As shown, the grain size is grade 5, with no impurity crystal structure and no microcracks.

[0044] Example 3: As Figure 2 As shown, the grain size is grade 5, with no impurity crystal structure and no microcracks.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for additive manufacturing of AlN magnesium-based alloys, characterized in that, Includes the following steps: Step S1: Preparation of metal powder. The metal powder includes the following elements by weight: Mg, 88.96~93.72 parts; Li, 2.3~3.4 parts; Nd, 2.1~3.1 parts; Zr, 0.5~0.7 parts; Zn, 2.8~3.2 parts; AlN, 4.6~8.4 parts. Step S2: Printing and molding. First, model the part. Then, spray the metal powder onto the printing platform according to the design path. Then, scan the path with a laser. After the metal powder melts and solidifies, the first layer of the part is built. Repeat the above actions to complete the part building layer by layer. Step S3: Solution treatment, heat the part to 350~390℃ and hold, then heat to 525~535℃ and hold. Step S4: Aging treatment, heating the parts to 280~320℃ and holding them at that temperature.

2. The additive manufacturing method for AlN magnesium-based alloys according to claim 1, characterized in that: In step S2, the power range of the laser is 60~100W.

3. The additive manufacturing method for AlN magnesium-based alloys according to claim 2, characterized in that: In step S2, the laser scanning speed is 600~1000mm / min and the laser scanning interval is 0.1~0.4mm.

4. The additive manufacturing method for AlN magnesium-based alloys according to claim 1, characterized in that: In step S2, the thickness of a single layer is 0.5~0.8mm.

5. The additive manufacturing method for AlN magnesium-based alloys according to claim 1, characterized in that: In step S2, helium and argon are used as protective gases.

6. The additive manufacturing method for AlN magnesium-based alloys according to claim 5, characterized in that: In step S3, the heat preservation time at 350~390℃ ranges from 1 to 2 hours.

7. The additive manufacturing method for AlN magnesium-based alloys according to claim 6, characterized in that: In step S3, the heat preservation time at 525~535℃ ranges from 1.5 to 2.5 hours.

8. The additive manufacturing method for AlN magnesium-based alloys according to claim 1, characterized in that: In step S3, the heating rate is 40~60℃ / h.

9. The additive manufacturing method for AlN magnesium-based alloys according to claim 1, characterized in that: In step S4, the heat preservation time at 280~320℃ ranges from 13 to 17 hours.

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