High-performance heterogeneous magnesium alloy and additive manufacturing method thereof

Abstract

The invention belongs to the field of additive manufacturing, and provides a high-performance heterogeneous magnesium alloy and an additive manufacturing method thereof.The additive manufacturing method comprises the steps that on a magnesium alloy substrate, fold line and straight line alternate additive manufacturing is conducted through two magnesium alloy welding wires; wherein a welding gun advances in a circulating broken line swinging mode during additive manufacturing of one magnesium alloy welding wire, the swinging radius ranges from 2 mm to 11 mm, the spacing distance between the centers of any two adjacent broken lines ranges from 2 mm to 8 mm, the advancing speed of the welding gun ranges from 3 mm / s to 15 mm / s, the welding current ranges from 90 A to 150 A, the welding voltage ranges from 12 V to 26 V, the wire feeding speed ranges from 4 m / min to 20 m / min, and after 1-10 layers of materials are added, the welding gun is cooled to 50 DEG C to 120 DEG C; and when the other magnesium alloy welding wire is subjected to additive manufacturing, the welding gun advances in a linear mode, the advancing speed of the welding gun is 4-16 mm / s, the welding current is 75-150 A, the welding voltage is 13-27 V, the wire feeding speed is 5-22 m / min, after 1-10 layers of materials are added, the welding gun is cooled to 55-125 DEG C, polishing is conducted to remove impurities, alternative additive manufacturing is conducted on the magnesium alloy base plate according to the two magnesium alloy welding wires, and the process is repeated. And finally, 30-80 layers of high-performance heterogeneous magnesium alloy are obtained.

Description

Technical Field

[0001] The present invention belongs to the field of additive manufacturing, and specifically relates to a high-performance heterogeneous magnesium alloy and an additive manufacturing method thereof. Background Art

[0002] As the lightest structural alloy, magnesium alloy has the advantages of high specific strength, good damping performance and excellent electromagnetic shielding performance in addition to low density. It is widely used in aviation, aerospace and transportation. At present, the more complex the shape of product parts, the higher the forming requirements. Traditional casting processes are difficult to meet the direct forming of complex-shaped components, and because molds are required in the manufacturing process, the manufacturing and R&D cycle is long, so a new alternative forming process is needed.

[0003] Additive Manufacturing (AM) is a new rapid prototyping technology. It uses a "bottom-up" material superposition method to efficiently and quickly form components with complex shapes. It does not require molds and has a short R&D cycle. It has been widely used in various metal forming. However, when using a single-component magnesium alloy welding wire for additive manufacturing, the performance of the additive manufacturing material is relatively single, and it is difficult to meet the needs of different fields. In addition, for low-alloy content alloys, the mechanical properties of additive manufacturing materials are relatively low. In order to improve the mechanical properties of the material, it is necessary to use a high alloy addition or high rare earth content welding wire or a multi-component welding wire for additive manufacturing. Among them, a high alloy addition or high rare earth content welding wire will increase the production cost. In addition, due to the poor compatibility between different component materials and poor interface bonding, the material will be delaminated and anisotropic and prone to cracks during the additive process, which will lead to a decrease in the mechanical properties of the material, premature fracture, uneven distribution of mechanical properties, and difficulty in simultaneously improving the strength and plasticity of the additive manufacturing material. At the same time, it is difficult to adjust the multi-component welding wire and its additive process parameters, resulting in high manufacturing costs and long cycles. Therefore, how to reduce raw material costs, simplify processes, shorten time cycles, enhance interface bonding, and improve the strength and plasticity of additive manufacturing materials are technical challenges that need to be solved urgently. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a high-performance heterogeneous magnesium alloy, and its additive manufacturing method comprises the following steps:

[0005] (1) grinding the surface of the magnesium alloy substrate with sandpaper and cleaning it with anhydrous ethanol, and then drying it with a hair dryer to remove stains and an oxide layer on the surface of the magnesium alloy substrate to obtain a magnesium alloy substrate with a clean surface;

[0006] (2) The magnesium alloy substrate obtained in step (1) is fixed on an additive manufacturing workbench, and under a protective gas, the protective gas flow rate is 10-28 L / min, and magnesium alloy welding wire 1 and magnesium alloy welding wire 2 are used to perform alternating additive manufacturing on the magnesium alloy substrate; the alternating additive manufacturing is: alternating zigzag and straight line additive manufacturing; wherein the zigzag additive manufacturing: the vertical distance between the welding gun and the substrate is adjusted to 10-26 mm, firstly, magnesium alloy welding wire 1 is used for additive manufacturing, and the welding gun moves in a zigzag swinging manner, the swing radius is 2-11 mm, and the spacing between any two adjacent zigzag centers during the zigzag swinging process is 2-8 mm, the travel speed of the welding gun is 3-15 mm / s, and the welding current is 9 0-150A, welding voltage is 12-26V, wire feeding speed is 4-20m / min, after additive manufacturing 1-10 layers, cool to 50-120°C, and grind to remove impurities; the linear additive manufacturing: using magnesium alloy welding wire 2 for additive manufacturing, the welding gun moves in a straight line, the welding gun travels at a speed of 4-16mm / s, the welding current is 75-150A, the welding voltage is 13-27V, the wire feeding speed is 5-22m / min, after additive manufacturing 1-10 layers, cool to 55-125°C, grind to remove impurities, and then perform alternating additive manufacturing on the magnesium alloy substrate according to the broken line additive manufacturing and the linear additive manufacturing; repeating the cycle, finally obtaining 30-80 layers of high-performance heterogeneous magnesium alloy;

[0007] The magnesium alloy in step (1) is one of AZ31 magnesium alloy, AZ51 magnesium alloy, ZK60 magnesium alloy or ZK61 magnesium alloy;

[0008] The protective gas in step (2) has a purity of ≥99.99% of high-purity argon or a mixture of argon and helium or a mixture of CO2 and argon; the volume ratio of argon to helium is 1.5-3:7-8.5; the volume ratio of CO2 to argon is 2-5:95-98;

[0009] The diameter of the magnesium alloy welding wire 1 is 1.1-6.0 mm;

[0010] The diameter of the magnesium alloy welding wire 2 is 1.2-5.8 mm;

[0011] The magnesium alloy welding wire 1 is one of AZ31 magnesium alloy welding wire and AZ51 magnesium alloy welding wire;

[0012] The magnesium alloy welding wire 2 is one of a ZK60 magnesium alloy welding wire and a ZK61 magnesium alloy welding wire.

[0013] Furthermore, the vertical distance between the welding gun in step (2) and the substrate is 11-19 mm.

[0014] Furthermore, the fold line additive manufacturing described in step (2) has: a swing radius of 3-10 mm, a spacing distance between the centers of any two adjacent fold lines during the fold line swinging process of 3-7 mm, a welding gun travel speed of 4-14 mm / s, a welding current of 95-145 A, a welding voltage of 13-25 V, and a wire feeding speed of 5-19 m / min.

[0015] Furthermore, in the linear additive manufacturing described in step (2), the travel speed of the welding gun is 5-13 mm / s, the welding current is 80-140 A, the welding voltage is 14-25 V, and the wire feeding speed is 6-21 m / min.

[0016] Furthermore, step (2) finally obtains 32-76 layers of high-performance heterogeneous magnesium alloy. DETAILED DESCRIPTION

[0017] Example 1

[0018] The preparation method of the high performance heterogeneous magnesium alloy 1 is as follows:

[0019] AZ31 magnesium alloy substrate, AZ31 and ZK60 magnesium alloy welding wires with wire diameters of 1.2mm;

[0020] Step 1: Grind the surface of the AZ31 magnesium alloy substrate with sandpaper and clean it with anhydrous ethanol, and then use a hair dryer to dry it to remove stains and oxide layers on the surface of the AZ31 magnesium alloy substrate to obtain an AZ31 magnesium alloy substrate with a clean surface.

[0021] Step 2: Fix the magnesium alloy substrate obtained in step (1) on an additive manufacturing workbench, under a shielding gas, the shielding gas is argon gas with a purity of 99.9%, and the shielding gas flow rate is 16L / min, and use AZ31 and ZK60 magnesium alloy welding wires to perform alternating additive manufacturing on the magnesium alloy substrate. The alternating additive manufacturing is alternating between zigzag and straight line additive manufacturing. Among them, zigzag additive manufacturing: the vertical distance between the welding gun and the substrate is adjusted to 12mm, and AZ31 magnesium alloy welding wire is first used for additive manufacturing. The welding gun moves in a cyclic zigzag swing mode, and the swing radius is 6mm. During the zigzag swing process, the spacing between any two adjacent zigzag centers is 4mm, the welding gun travels at a speed of 7mm / s, the welding current is 110A, the welding voltage is 14V, and the wire feeding speed is 7m / min. After adding one layer, cool to 50°C and grind to remove impurities; the linear additive manufacturing: use ZK60 magnesium alloy welding wire for additive manufacturing, the welding gun moves in a straight line, the welding gun moves at a speed of 6mm / s, the welding current is 100A, the welding voltage is 14V, and the wire feeding speed is 6.2m / min. After one layer of additive manufacturing is completed, cool to 55°C, grind to remove impurities, and then perform alternating additive manufacturing on the magnesium alloy substrate according to the above-mentioned two magnesium alloy welding wires, and repeat this cycle to finally obtain 38 layers of high-performance heterogeneous magnesium alloy 1.

[0022] Example 2

[0023] The preparation method of high performance heterogeneous magnesium alloy 2 is as follows:

[0024] AZ31 magnesium alloy substrate, AZ31 and ZK60 magnesium alloy welding wire with a wire diameter of 1.4mm;

[0025] Step 1: Grind the surface of the AZ31 magnesium alloy substrate with sandpaper and clean it with anhydrous ethanol, and then use a hair dryer to dry it to remove stains and an oxide layer on the surface of the AZ31 magnesium alloy substrate to obtain an AZ31 magnesium alloy substrate with a clean surface.

[0026] Step 2: Fix the magnesium alloy substrate obtained in step (1) on an additive manufacturing workbench, under a protective gas, the protective gas is argon with a purity of 99.9%, and the protective gas flow rate is 18L / min, and use AZ31 and ZK60 magnesium alloy welding wires to perform alternating additive manufacturing on the magnesium alloy substrate. The alternating additive manufacturing is alternating between zigzag and straight line additive manufacturing. Among them, zigzag additive manufacturing: the vertical distance between the welding gun and the substrate is adjusted to 14mm, and AZ31 magnesium alloy welding wire is first used for additive manufacturing. The welding gun moves in a cyclic zigzag swing mode, and the swing radius is 7mm. During the zigzag swing process, the spacing between any two adjacent zigzag centers is 5mm, the welding gun travels at a speed of 6.6mm / s, the welding current is 100A, the welding voltage is 13.6V, and the wire feeding speed is 6.6m / min. After adding 2 layers, cool to 70℃ and grind to remove impurities; the linear additive manufacturing: use ZK60 magnesium alloy welding wire for additive, the welding gun moves in a straight line, the welding gun travels at a speed of 8.5mm / s, the welding current is 120A, the welding voltage is 14.6V, and the wire feeding speed is 7m / min. After adding 2 layers, cool to 80℃, grind to remove impurities, and then perform additive manufacturing alternately on the magnesium alloy substrate according to the above two magnesium alloy welding wires. Repeat this cycle to finally obtain 40 layers of high-performance heterogeneous magnesium alloy 2.

[0027] Comparative Example 1

[0028] The preparation method of additively manufactured magnesium alloy 3 is as follows:

[0029] AZ31 magnesium alloy substrate is used, and the welding wire diameter is 1.2mm.

[0030] Step 1: Grind the surface of the AZ31 magnesium alloy substrate with sandpaper and clean it with anhydrous ethanol, and then dry it with a hair dryer to remove stains and an oxide layer on the surface of the AZ31 magnesium alloy substrate to obtain an AZ31 magnesium alloy substrate with a clean surface.

[0031] Step 2: Fix the magnesium alloy substrate obtained in step (1) on the additive manufacturing workbench, and use AZ31 magnesium alloy welding wire to perform additive manufacturing on the AZ31 magnesium alloy substrate obtained in step 1 under argon protection with an argon flow rate of 17L / min. The additive manufacturing is as follows: the vertical distance between the welding gun and the AZ31 substrate is adjusted to 15mm, the welding gun moves in a cyclic zigzag swing mode, the swing radius is 5mm, the spacing between any two adjacent zigzag centers during the zigzag swing process is 6mm, the welding gun travels at a speed of 8mm / s, the welding current is 125A, the welding voltage is 15V, and the wire feeding speed is 7.6m / min. After each layer of additive manufacturing is completed, it is cooled to 75°C and polished to remove the impurity layer, and then the next layer of additive manufacturing is performed, and finally a 36-layer additively manufactured magnesium alloy 3 is obtained.

[0032] Comparative Example 2

[0033] The preparation method of additively manufactured magnesium alloy 4 is as follows:

[0034] AZ31 magnesium alloy substrate and ZK60 magnesium alloy welding wire with a wire diameter of 1.2mm are used;

[0035] Step 1: Grind the surface of the AZ31 magnesium alloy substrate with sandpaper and clean it with anhydrous ethanol, and then dry it with a hair dryer to remove stains and an oxide layer on the surface of the AZ31 magnesium alloy substrate to obtain an AZ31 magnesium alloy substrate with a clean surface.

[0036] Step 2: Fix the magnesium alloy substrate obtained in step (1) on the additive manufacturing workbench, and use ZK60 magnesium alloy welding wire to perform additive manufacturing on the AZ31 magnesium alloy substrate obtained in step 1 under argon protection with an argon flow rate of 19L / min. The additive manufacturing is as follows: the vertical distance between the welding gun and the AZ31 substrate is adjusted to 13mm, the welding gun moves in a straight line, the welding gun travels at a speed of 6mm / s, the welding current is 105A, the welding voltage is 16V, and the wire feeding speed is 8m / min. After each additive manufacturing layer, it is cooled to 80°C and polished to remove the impurity layer, and then the next layer of additive manufacturing is performed, and finally a 34-layer additively manufactured magnesium alloy 4 is obtained.

[0037] Comparative Example 3

[0038] The preparation method of heterogeneous magnesium alloy 5 is as follows:

[0039] AZ31 magnesium alloy substrate, AZ31 and ZK60 magnesium alloy welding wire with a wire diameter of 1.0mm;

[0040] Step 1: Grind the surface of the AZ31 magnesium alloy substrate with sandpaper and clean it with anhydrous ethanol, and then use a hair dryer to dry it to remove stains and an oxide layer on the surface of the AZ31 magnesium alloy substrate to obtain an AZ31 magnesium alloy substrate with a clean surface.

[0041] Step 2: The magnesium alloy substrate obtained in step (1) is fixed on an additive manufacturing workbench, and under a protective gas, the protective gas is argon gas with a purity of 99.9% and the protective gas flow rate is 30L / min, and AZ31 and ZK60 magnesium alloy welding wires are used to perform alternating additive manufacturing on the magnesium alloy substrate. The alternating additive manufacturing is alternating between folded line and straight line additive manufacturing. The zigzag additive manufacturing: the vertical distance between the welding gun and the substrate is adjusted to 9mm, and AZ31 magnesium alloy welding wire is first used for additive manufacturing. The welding gun moves in a cyclic zigzag swing mode with a swing radius of 12mm. During the zigzag swing process, the spacing between any two adjacent zigzag centers is 1.5mm. The welding gun moves at a speed of 2.5mm / s, the welding current is 85A, the welding voltage is 11.6V, and the wire feeding speed is 3.6m / min. After adding 2 layers, it is cooled to 40°C and polished to remove impurities. The linear additive manufacturing: ZK60 magnesium alloy welding wire is used for additive manufacturing. The welding gun moves in a linear manner with a speed of 3.5mm / s, the welding current is 70A, the welding voltage is 12.6V, and the wire feeding speed is 4.5m / min. After 2 layers of additive manufacturing are completed, it is cooled to 45°C, polished to remove impurities, and then the above-mentioned two magnesium alloy welding wires are used for alternating additive manufacturing on the magnesium alloy substrate. This cycle is repeated to finally obtain 20 layers of heterogeneous magnesium alloy 5.

[0042] Table 1 Comparison of component performance obtained in Examples 1-2 and Comparative Examples 1-3

[0043]

[0044] As can be seen from Table 1, the number of layers of Examples 1 and 2 is higher than that of Comparative Examples 1, 2 and 3. According to prior art reports, the higher the number of layers, the worse the performance, but the strength and plasticity of the alloys obtained in Examples 1 and 2 are higher than those obtained in Comparative Examples 1-3. Moreover, the performance is poor when only AZ31 magnesium alloy welding wire is used for additive manufacturing, such as Comparative Example 1. However, when two magnesium alloy welding wires are used for alternating additive manufacturing, the mechanical properties (Examples 1 and 2) are significantly improved compared to the strength and plasticity of a single AZ31 magnesium alloy (Comparative Example 1), and exceed the mechanical properties of a single ZK60 magnesium alloy additive component (Comparative Example 2). In addition, according to prior art reports, when heterogeneous welding wires are used for additive manufacturing, it is difficult to improve strength and plasticity simultaneously, that is, when strength is improved, plasticity will be reduced. By comparison, compared with the prior art, the present invention has achieved unexpected technical effects, not only in terms of strength, but also in terms of plasticity, achieving a simultaneous improvement in strength and plasticity. In addition, comparative example 3 and the present invention use the same alloy and process, but the relevant process parameters are not within the scope of protection of the claims of the present invention, but its strength and plasticity are lower than the minimum performance of the material obtained by the present invention. This shows that although a similar process to the present invention is used, only within the scope of protection of the claims of the present invention can the simultaneous improvement of the strength and plasticity of heterogeneous materials in additive manufacturing be achieved.

[0045] The present invention realizes the additive manufacturing of heterogeneous welding wires through the coordinated regulation of welding wires, substrates, processes and process parameters, and effectively solves the problems faced by the prior art: when two welding wires are alternately additively manufactured, the interface between materials of different components is not well bonded and easily broken, and the compatibility of the two component materials is poor, resulting in stratification and anisotropy of the material during the additive process, which ultimately leads to the decline of mechanical properties of the material, uneven distribution of mechanical properties, difficulty in synchronously improving the strength and plasticity of additive manufacturing materials, and difficulty in meeting the technical difficulties of different performances at different positions with a single welding wire. The present invention obtains higher performance than that of a single-component additive manufacturing component, simplifies the process and reduces the cost of raw materials without adding rare earth or high-content elements, significantly improves the strength and plasticity of the additive manufacturing material, obtains performance equivalent to that of materials containing rare earth elements, and simultaneously improves the strength and plasticity of the alloy, which are higher than the strength and plasticity of any component therein. At the same time, the additive manufacturing material obtains the following organizational structure: good bonding at the interface junction, good compatibility, stable performance, effective suppression of stratification, local and overall anisotropy, and is suitable for the industrial production of additive manufacturing materials with uniform performance or different performances at different positions.

Claims

1. A high performance heterogeneous magnesium alloy, characterized in that: Its additive manufacturing method includes the following steps: (1) grinding the surface of the magnesium alloy substrate with sandpaper and cleaning it with anhydrous ethanol, and then drying it with a hair dryer to remove stains and an oxide layer on the surface of the magnesium alloy substrate to obtain a magnesium alloy substrate with a clean surface; (2) The magnesium alloy substrate obtained in step (1) is fixed on an additive manufacturing workbench, and under a protective gas, the protective gas flow rate is 10-28 L / min, and magnesium alloy welding wire 1 and magnesium alloy welding wire 2 are used to perform alternating additive manufacturing on the magnesium alloy substrate; the alternating additive manufacturing is: alternating zigzag and straight line additive manufacturing; wherein the zigzag additive manufacturing: the vertical distance between the welding gun and the substrate is adjusted to 10-26 mm, firstly, magnesium alloy welding wire 1 is used for additive manufacturing, and the welding gun moves in a zigzag swinging manner, the swing radius is 2-11 mm, and the spacing between any two adjacent zigzag centers during the zigzag swinging process is 2-8 mm, the travel speed of the welding gun is 3-15 mm / s, and the welding current is 9 0-150A, welding voltage is 12-26V, wire feeding speed is 4-20m / min, after additive manufacturing 1-10 layers, cool to 50-120°C, and grind to remove impurities; the linear additive manufacturing: using magnesium alloy welding wire 2 for additive manufacturing, the welding gun moves in a straight line, the welding gun travels at a speed of 4-16mm / s, the welding current is 75-150A, the welding voltage is 13-27V, the wire feeding speed is 5-22m / min, after additive manufacturing 1-10 layers, cool to 55-125°C, grind to remove impurities, and then perform alternating additive manufacturing on the magnesium alloy substrate according to the broken line additive manufacturing and the linear additive manufacturing; repeating the cycle, finally obtaining 30-80 layers of high-performance heterogeneous magnesium alloy; The magnesium alloy described in step (1) is one of AZ31 magnesium alloy, AZ51 magnesium alloy, ZK60 magnesium alloy or ZK61 magnesium alloy; the protective gas described in step (2) is high-purity argon gas with a purity of ≥99.99% or a mixture of argon and helium or a mixture of CO2 and argon; the volume ratio of argon and helium is 1.5-3:7-8.5; the volume ratio of CO2 and argon is 2-5:95-98; The diameter of the magnesium alloy welding wire 1 is 1.1-6.0 mm; The diameter of the magnesium alloy welding wire 2 is 1.2-5.8 mm; The magnesium alloy welding wire 1 is one of AZ31 magnesium alloy welding wire and AZ51 magnesium alloy welding wire; The magnesium alloy welding wire 2 is one of a ZK60 magnesium alloy welding wire and a ZK61 magnesium alloy welding wire.

2. A high performance heterogeneous magnesium alloy according to claim 1, characterized in that: The vertical distance between the welding gun and the substrate in step (2) is 11-19 mm.

3. A high performance heterogeneous magnesium alloy according to claim 1, characterized in that: The fold line additive manufacturing described in step (2): the swing radius is 3-10 mm, the spacing between any two adjacent fold line centers during the fold line swing process is 3-7 mm, the welding gun travel speed is 4-14 mm / s, the welding current is 95-145 A, the welding voltage is 13-25 V, and the wire feeding speed is 5-19 m / min.

4. A high performance heterogeneous magnesium alloy according to claim 1, characterized in that: The linear additive manufacturing described in step (2): the travel speed of the welding gun is 5-13 mm / s, the welding current is 80-140 A, the welding voltage is 14-25 V, and the wire feeding speed is 6-21 m / min.

5. The high performance heterogeneous magnesium alloy according to claim 1, characterized in that: The step (2) finally produces 32-76 layers of high-performance heterogeneous magnesium alloy.

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