High-strength and high-plasticity rare earth magnesium alloy material and electric arc additive manufacturing process and application thereof

Abstract

The invention relates to the technical field of additive manufacturing, and particularly discloses a high-strength and high-plasticity rare earth magnesium alloy material and an electric arc additive manufacturing process and application thereof. According to the rare earth magnesium alloy material provided by the invention, the composite rare earth element (Nd / Sm) and the microalloying element (Zr / Ca) are introduced, and high-energy gradient pulse treatment and laser shock treatment are combined, so that the strength and plasticity matching degree of the magnesium alloy is remarkably improved, and the technical bottleneck that the strength and plasticity of a traditional rare earth magnesium alloy material are difficult to collaboratively optimize is solved; and a new thought is provided for research and development of the high-performance magnesium alloy material, the application field of the rare earth magnesium alloy material is expanded, the product production efficiency is high, batch industrial production can be achieved, and the high application and popularization value is achieved.

Description

Technical Field

[0001] The present invention relates to the field of additive manufacturing technology, and in particular to a high-strength and high-plasticity rare earth magnesium alloy material and an arc additive manufacturing process and application thereof. Background Art

[0002] With the advancement of science and technology and the ever-increasing demand for vehicle endurance, the development of lightweight equipment has become crucial. Magnesium alloys, due to their exceptional performance advantages, have attracted significant attention. As the lightest engineering structural material currently available, magnesium alloys offer advantages such as low density, high specific strength, and high specific stiffness, holding enormous potential for application in the automotive, aerospace, military, and electronic communications sectors. Currently, magnesium alloys are primarily produced through casting and extrusion. Castings often exhibit defects such as low density, porosity, and cracks, resulting in poor mechanical properties. Hot extrusion at high temperatures forms a loose, porous, and non-protective oxide film, which further oxidizes the magnesium alloy. This oxidation process releases significant heat, reaching temperatures as high as 2850°C. Furthermore, magnesium's extremely high saturated vapor pressure can cause explosions at high temperatures, making the process highly hazardous. Furthermore, casting and extrusion often require cumbersome subtractive machining and post-processing to produce complex components, resulting in wasteful raw materials and reduced production efficiency. The emergence of additive manufacturing technology has brought new opportunities for the manufacture of magnesium alloy components. Among them, arc additive manufacturing technology has the advantages of high material utilization, low equipment cost, low environmental requirements, and the ability to form larger-sized parts with faster efficiency. It is suitable for the efficient production of large magnesium alloy components.

[0003] However, traditional Mg-Al and Mg-Zn alloys have inherent limitations, such as low elastic modulus, low strength, poor plasticity and ductility, which hinder their application in structures. With the development of aerospace and military fields, higher requirements are placed on the performance of magnesium alloys. On the basis of magnesium alloys, the comprehensive performance of alloys can be further improved through trace element alloying and multi-element alloying technology. Adding rare earth elements to magnesium alloys can effectively improve the strength and plastic deformation ability of magnesium alloys. It has been widely used in steel and non-ferrous metal alloys and is one of the most effective ways to improve the performance of magnesium alloys. However, due to the hexagonal close-packed crystal structure of magnesium alloys, few slip systems, and poor room temperature plastic deformation ability, the difficulty of wire preparation increases, making it difficult to control the composition of fused wire additives and increasing costs. In addition, there are currently few types of commercial rare earth magnesium alloy welding wires on the market. The wires often contain a large amount of hard and brittle phases, which makes processing difficult during wire preparation and difficult to mass produce. The mechanical properties of alloys made from rare earth magnesium alloy wires customized by a few existing laboratories increase with the increase of rare earth content in the wires. However, when the rare earth content is higher than a certain level, the plasticity of the material will be weakened, which increases the risk of wire breakage during the forming of the magnesium alloy wire and limits the addition of rare earth elements. In terms of strength, the tensile strength and yield strength of rare earth magnesium alloys manufactured by arc additive manufacturing can be effectively improved through existing heat treatment methods, but the plasticity of the alloy is severely lost, making it difficult to balance the strength and plasticity of high-performance rare earth magnesium alloys, seriously affecting their scope of use. It can be seen that in the performance of magnesium alloys, strength and plastic toughness have a mutually constrained relationship, and in some cases the two even present an opposing trend. Therefore, how to find a balance between strength and plasticity in the research and development and application of rare earth magnesium alloys has become a key problem that needs to be overcome urgently. Summary of the Invention

[0004] To address the difficulty in balancing the strength and ductility of existing magnesium alloys, which severely limits their application, the present invention provides a high-strength, high-ductility rare earth magnesium alloy material, its arc additive manufacturing process, and its application. By introducing rare earth elements Nd and Sm into the magnesium alloy material in synergistic relationship with Zr and Ca, and then subjecting it to high-energy pulse and laser shock composite processing, the present invention produces a high-performance rare earth magnesium alloy material. This effectively resolves the mutual constraints between strength and ductility in magnesium alloys, providing a new research direction for the preparation of high-performance magnesium alloys.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0006] A high-strength and high-plasticity rare earth magnesium alloy material comprises the following components by weight: Al 6% to 12%, Nd 1% to 10%, Sm 1% to 6%, Zn 0.5% to 1.5%, Zr 0.1% to 0.5%, Ca 0.05% to 0.3%, Mn 0.1% to 1%, and the balance being magnesium and unavoidable impurities.

[0007] Compared with the prior art, the high-strength and high-plasticity rare earth magnesium alloy material provided by the present invention has Al as a strengthening phase, thereby improving the strength and hardness of the alloy; the rare earth elements Nd and Sm can effectively hinder dislocation movement through mechanisms such as grain refinement, solid solution strengthening and dispersion strengthening, thereby significantly improving the strength of the material; in addition, the addition of rare earth elements Nd and Sm can significantly improve the heat resistance of the alloy; Nd and Sm can form compounds with high thermal stability, which hinder the migration of grain boundaries and grain growth at high temperatures, thereby improving the thermal stability of the alloy, enabling it to maintain good mechanical properties at higher temperatures, and expanding the material's operating temperature range; appropriate amounts of Zn and Zr help improve the plasticity of the alloy; in addition, the addition of Ca and Zr can synergistically refine the grains and inhibit oxidation, thereby solving the problem of stabilizing the molten pool stability in the additive manufacturing process.

[0008] The rare earth magnesium alloy material provided by the present invention mainly realizes the coordinated optimization of strength and plasticity through the synergistic effect of the four elements Nd, Sm, Ca and Zr. Nd, Sm and Zr form nano-scale heterogeneous nucleation cores (such as Mg 12 Nd, Mg3Sm, ZrMg2) form a three-dimensional network of heterogeneous nucleation sites. Ca promotes the stable existence of heterogeneous nucleation cores by reducing the interfacial energy, forming a denser grain refinement network. During the cooling process, the solid solution strengthening of Nd / Sm and the grain boundary segregation strengthening of Ca form a gradient strengthening structure. In the subsequent additive manufacturing reprocessing process, Sm, Nd, and Zr can regulate the dynamic recrystallization process, provide more recrystallization nucleation sites, and inhibit the coarsening of the precipitate phase. This multi-scale synergistic mechanism breaks through the bottleneck of traditional magnesium alloys that cannot be coordinated to optimize strength and plasticity, and enables rare earth magnesium alloy materials to achieve a yield strength of 190MPa to 250MPa, a tensile strength of 300MPa to 380MPa, and an elongation of 14% to 20%. It provides magnesium alloy materials with excellent performance for aerospace, automotive lightweighting, electronic packaging and other fields.

[0009] The present invention also provides an arc additive manufacturing process for a high-strength and high-plasticity rare earth magnesium alloy material, which comprises the following steps:

[0010] S1. Prepare a cored wire containing Nd, Sm, Zr and Ca; the cored wire comprises a Mg-Al alloy sheath and a core powder, wherein the core powder comprises Nd powder, Sm powder, ZrO2 powder and CaCO3 powder;

[0011] S2. Using AZ31B magnesium alloy welding wire as main wire, the flux-cored filler wire as auxiliary wire, and Mg alloy plate as substrate, a twin-wire arc additive manufacturing device is used to perform additive manufacturing to obtain an additively manufactured workpiece;

[0012] S3. Subjecting the additively manufactured workpiece to high-energy gradient pulse processing and laser shock processing in sequence to obtain a high-strength and high-plasticity rare earth magnesium alloy material.

[0013] The twin-wire arc additive manufacturing process for rare earth magnesium alloy materials provided by the present invention significantly improves the strength-plasticity matching of magnesium alloys by introducing composite rare earth elements (Nd / Sm) and microalloying elements (Zr / Ca), and combining high-energy gradient pulse processing and laser shock processing. This solves the technical bottleneck of the difficulty in synergistic optimization of strength and plasticity in traditional rare earth magnesium alloy materials, provides new ideas for the research and development of high-performance magnesium alloy materials, is conducive to expanding the application field of rare earth magnesium alloy materials, and has high production efficiency, can be mass-produced industrially, and has high promotion and application value.

[0014] As a specific embodiment of the present invention, the preparation method of the drug core filling wire comprises the following steps:

[0015] Cut the cold-rolled aluminum strip into narrow strips and clean them to remove surface impurities;

[0016] Nd powder, Sm powder, ZrO2 powder and CaCO3 powder are sieved, dried and then mixed evenly to obtain core powder;

[0017] The cleaned aluminum strip is cold-bent into a U-shaped tube, the core powder is added, the U-shaped tube is closed, and an O-shaped tube is formed; then, the formed O-shaped tube is drawn to achieve the required size and performance requirements.

[0018] It should be noted that the drawn wire can be processed to achieve the desired performance requirements. The specific processing methods can be conventionally performed using existing techniques in the art. The prepared wire is packaged into coils or tubes. The coiled wire is encapsulated in a plastic sleeve and then placed in a desiccant to protect it from moisture. The encapsulated material is then placed in a cardboard box for later use. The aforementioned flux-cored filler wire can also be produced using other conventional methods in the art. These processes are currently well-established and are not specifically limited in this invention.

[0019] Specifically, the cold-rolled aluminum strip may be a 5052 aluminum alloy strip.

[0020] As a specific embodiment of the present invention, the magnesium alloy substrate can be an AZ31 magnesium alloy substrate.

[0021] Furthermore, the magnesium alloy substrate was pretreated before additive manufacturing: the surface of the magnesium alloy substrate was polished with an angle grinder, the oxide layer was thoroughly cleaned, and then it was cleaned with anhydrous ethanol and dried.

[0022] Furthermore, in S2, the cold metal transition additive power source used is a single heat source, and additive manufacturing is performed under the protection of an inert gas, with a flow rate of the inert gas being 15 L / min to 25 L / min.

[0023] Specifically, high-purity argon with a purity of ≥99.999% is selected as the protective gas.

[0024] Furthermore, in S2, the diameter of the AZ31B magnesium alloy welding wire is 1.2 mm.

[0025] Furthermore, the core filling wire includes the following components in weight percentage: Nd powder 5% to 35%, Sm powder 1% to 20%, ZrO2 powder 1% to 10%, CaCO3 powder 1% to 10%, AZ31B magnesium alloy powder 0% to 10%, and the balance is Al-Mg alloy outer skin; wherein, the mass ratio of ZrO2 powder to CaCO3 powder is not less than 5:3, and the total mass is 5% to 10% of the total mass of the core filling wire; the core powder accounts for 40% to 50% of the total mass of the core filling wire.

[0026] Preferably, the cored wire comprises the following components in percentage by weight: 10% to 30% Nd powder, 8% to 15% Sm powder, 1% to 9% ZrO2 powder, 1% to 7% CaCO3 powder, 0% to 10% AZ31B magnesium alloy powder, and the remainder is Al-Mg alloy sheath.

[0027] Furthermore, the core medicine powder has a particle size of 15 μm to 50 μm.

[0028] By controlling the particle size of the core powder to 15μm to 50μm, the elements in the molten pool can be homogenized.

[0029] Furthermore, the diameter of the core filling wire is 3 mm to 5 mm.

[0030] Furthermore, in S2, the welding current of the additive manufacturing is 90A to 150A, the welding voltage is 12V to 20V, the welding speed is 0.3m / min to 0.7m / min, and the height of the welding gun from the substrate is 8mm to 15mm.

[0031] Furthermore, in S2, the angle between the main wire and the auxiliary wire is 30° to 80°, and the main wire is perpendicular to the horizontal workbench.

[0032] Furthermore, in S2, the main arc-starting wire has a stem extension of 10 mm to 14 mm, and the bypass auxiliary wire has a stem extension of 9 mm to 15 mm.

[0033] Furthermore, in S2, the wire feeding speed of the main wire is 6m / min to 12m / min, the wire feeding speed of the auxiliary wire is 0.2m / min to 3m / min, and the wire feeding speed ratio of the main wire to the auxiliary wire is (5 to 50):1.

[0034] Controlling the feed speeds of the main and auxiliary wires within a moderate range helps regulate the energy input and solidification process of the molten pool, promoting a more uniform distribution of alloying elements within the molten pool, and ultimately, a more uniform phase composition, improving the consistency and stability of material properties. Furthermore, a reasonable wire feed speed ratio can achieve an optimal match between the composition and microstructure of the deposited metal, thereby increasing material strength and avoiding structural defects caused by improper wire feed speeds, such as coarse grains and uneven phase distribution. This improves material toughness and contributes to a systematic improvement in overall performance.

[0035] It should be noted that the twin-wire arc additive manufacturing process of the present invention is carried out using conventional process flows in the art. Specifically, a magnesium alloy substrate is fixed to a printing table, an AZ31B magnesium alloy welding wire is fed under the welding gun, and an auxiliary flux-cored filler wire is bypassed. Single-pass, layer-by-layer welding is performed in a reciprocating manner, with the length of the magnesium alloy substrate serving as the printing direction. After each weld, the oxide film on the printed part surface is cleaned, and the next layer is welded again after the interlayer temperature reaches a certain value. This reciprocating process is repeated until the target height is reached, thereby producing a magnesium alloy arc additive component.

[0036] Complex components require model design and path planning. First, CAD software is used to design the required 3D model, determining its structure and dimensions as the basis for subsequent printing. Computer-aided manufacturing (CAM) software then generates a printing path based on the designed model. Path planning considers factors such as the model's shape and dimensions, as well as the printing process requirements, to ensure that the arc can deposit material layer by layer along a predetermined trajectory during printing, forming the desired 3D shape. Path planning analyzes and quantifies various geometric and positional parameters to generate environmental information for robot motion, allowing the robot to plan the optimal path from a known point to the target endpoint. An adaptive layering algorithm based on triangular facets is then used to generate the path plan for the additive manufacturing task. A CCD sensor system monitors the shape, size, and temperature distribution of the melt pool in real time. Important parameters such as arc length, liquid melt pool morphology, and layer height and width are monitored. Monitoring the melt pool morphology allows for timely detection of anomalies during the forming process, such as excessive or insufficient melt pools or irregular shapes. Based on the melt pool monitoring results, computational control enables real-time adjustments to arc parameters and wire feed speed, achieving closed-loop control. For example, when it is monitored that the molten pool temperature is too high, the current can be appropriately reduced or the distance between the electrode and the substrate can be increased to reduce the heat input; when it is found that the molten pool size does not meet the requirements, the wire feed speed can be adjusted or the printing path can be changed to correct the forming size deviation and ensure the quality and accuracy of the formed part.

[0037] Furthermore, in S3, the voltage of the high energy gradient pulse treatment is 3000V to 4000V, and the current density is 150A / mm 2 ~250A / mm 2 , the duty cycle is 30% to 40%, the frequency is 20Hz to 50Hz, and the processing time is 0.5s to 3s.

[0038] The instantaneous high energy input generated by high-energy pulses will cause local areas of the additively manufactured parts to undergo rapid heating and cooling processes. This unbalanced thermal effect can promote the formation of a large number of crystal nuclei and inhibit the growth of grains, thereby obtaining a fine and uniform grain structure. In addition, high-energy pulse processing can dynamically adjust the internal structure of the material through instantaneous energy release, promote the diffusion and uniform distribution of elements, reduce component segregation, thereby improving the uniformity of the microstructure, and thus facilitating the synergistic improvement of strength and plasticity.

[0039] Furthermore, in S3, the energy density of the laser shock treatment is 8 J / cm 2 ~12J / cm 2 , the pulse width is 8ns~10ns, and the number of impacts is 1~3 times.

[0040] Laser shock treatment uses a high-energy-density laser beam to act on the surface of a material, causing plastic deformation of the surface layer. Because the volume expansion of the surface material is constrained by the underlying material, residual compressive stress and high-density dislocations are introduced on the surface of the material. These residual compressive stress and high-density dislocations can offset some of the tensile stress generated by the working load, thereby improving the elongation and creep resistance of the material. In addition, in Nd / Sm alloys, there are some precipitated phases, such as Mg-Nd phases. These precipitated phases have strong interfacial bonding with the matrix. When laser shock treatment generates a large number of dislocations in the alloy, these precipitated phases with strong interfacial bonding with the matrix will pin the dislocations, further hindering dislocation movement, thereby further improving the elongation and creep resistance.

[0041] The present invention also provides applications of the high-strength and high-plasticity rare earth magnesium alloy material in the fields of automobiles, aerospace, military industry, electronic communications, etc.

[0042] The magnesium alloy material of the present invention precisely controls the alloy composition and its ratio, and adopts a combination of twin-wire arc additive manufacturing technology and high-energy pulse + laser shock processing technology, while improving the plasticity and strength of the magnesium alloy material, which can effectively solve the problem of mutual restriction between the strength and plastic toughness of the magnesium alloy. It has low manufacturing cost and high production efficiency, which is conducive to industrial large-scale production. It provides a new rare earth magnesium alloy material with excellent performance for the fields of automobiles, aerospace, military industry or electronic communications, and has high potential application value. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0044] In order to better illustrate the present invention, further examples are given below.

[0045] The preparation method of the drug-core filled wire used in the following examples and comparative examples includes the following steps:

[0046] Cut the 5052 aluminum alloy strip into narrow strips and clean them to remove surface impurities;

[0047] Nd powder, Sm powder, ZrO2 powder and CaCO3 powder are sieved, dried and then mixed evenly to obtain core powder;

[0048] The cleaned aluminum strip is cold-bent into a U-shaped tube, the core powder is added, and the U-shaped tube is closed to form an O-shaped tube. The formed O-shaped tube is then drawn to obtain a cored wire. The powder in the cored wire has a particle size of 15 to 48 μm and a diameter of 3 mm.

[0049] The AZ31B magnesium alloy substrate was pretreated before use. The specific pretreatment process was as follows: the surface of the magnesium alloy substrate was polished with an angle grinder, the oxide layer was thoroughly cleaned, and then it was cleaned with anhydrous ethanol and dried.

[0050] The composition of AZ31B welding wire is: Al 3.00%, Zn 1.0%, Mn 0.5%, with the balance being Mg and unavoidable impurities. The diameter of AZ31B welding wire is 1.2 mm.

[0051] Example 1

[0052] A high-strength and high-plasticity rare earth magnesium alloy material comprises the following components by weight: Al 11.76%, Nd 8.26%, Sm 2.75%, Zn 0.75%, Zr 0.27%, Ca 0.20%, Mn 0.31%, and the balance being magnesium and unavoidable impurities.

[0053] The specific preparation process of the above-mentioned high-strength and high-plasticity rare earth magnesium alloy material is as follows:

[0054] Step 1: Prepare a cored wire according to the above process, wherein the cored wire comprises the following components by weight: Al 42.1%, Nd 30%, Sm 10%, Zn 0.1%, ZrO2 4%, CaCO3 2%, and the balance being magnesium and unavoidable impurities;

[0055] Step 2: Fix the pretreated AZ31B magnesium alloy substrate on the printing table, feed the AZ31B magnesium alloy welding wire under the welding gun, and bypass the auxiliary flux-cored filling wire so that the two welding wires are in the same plane, the main wire is perpendicular to the horizontal workbench, adjust the angle between the main wire and the auxiliary wire to 75° and make the ends of their axes intersect at one point, and feed them by two wire feeders. The main wire dry elongation is 10mm, the auxiliary wire dry elongation is 10mm, the main wire feeding speed is 8.5m / min, the auxiliary wire feeding speed is 0.4m / min, and the cold metal transfer arc is used as the heat source. The tip of the welding gun is The distance from the substrate was 10 mm, the welding gun was perpendicular to the workpiece, and single-pass reciprocating welding was performed layer by layer with the length direction of the magnesium alloy substrate as the printing direction. The welding current was 100 A, the welding voltage was 15 V, the welding speed was 0.5 m / min, the single-pass layer length was set to 12 cm, the single-layer weld height was 3 mm, the weld width was 7 mm, and the welding gun lifting height was 3.2 mm. After each welding, the oxide film on the surface of the printed part was cleaned and the next layer was welded again after waiting for the interlayer temperature to reach a certain value. The interlayer cooling time was 5 min. 15 layers were stacked to obtain a magnesium alloy arc additive component.

[0056] Step 3: Perform short-term high-energy pulse treatment on the magnesium alloy arc additive component with a voltage of 4000V and a current density of 200A / mm 2, duty cycle 35%, frequency 30 Hz, processing time 2 s, and then laser shock peening with energy density 8 J / cm 2 , pulse width 10ns, impact number 2 times, and magnesium alloy arc additive product was obtained.

[0057] According to the ISO 6892-1-2009 standard test method, three vertical (parallel to the BD) and horizontal (perpendicular to the BD) tensile test specimens were prepared by wire electrode cutting. Yield strength and tensile strength tests were carried out using a C45.105 universal tensile testing machine parallel to the BD and perpendicular to the BD tensile section. The test speed was 1 mm / min and the tensile tests were performed at room temperature (25°C).

[0058] After testing, its room temperature yield strength is 230MPa, tensile strength is 375MPa, and elongation is 20%.

[0059] Example 2

[0060] A high-strength and high-plasticity rare earth magnesium alloy material comprises the following components by weight: Al 9.70%, Nd 5.86%, Sm 1.81%, Zn 0.89%, Zr 0.3%, Ca 0.17%, Mn 0.27%, and the balance being magnesium and unavoidable impurities.

[0061] The specific preparation process of the above-mentioned high-strength and high-plasticity rare earth magnesium alloy material is as follows:

[0062] Step 1: Prepare a cored wire according to the above process, wherein the cored wire comprises the following components by weight: Al 44%, Nd 35%, Sm 8%, Zn 0.2%, ZrO2 5%, CaCO3 3%, and the balance being magnesium and unavoidable impurities;

[0063] Step 2: Fix the pretreated AZ31B magnesium alloy substrate on the printing table, feed the AZ31B magnesium alloy welding wire under the welding gun, and bypass the auxiliary flux-cored filling wire so that the two welding wires are in the same plane, the main wire is perpendicular to the horizontal workbench, adjust the angle between the main wire and the auxiliary wire to 40° and make the ends of their axes intersect at one point, and feed them by two wire feeders. The main wire dry elongation is 13mm, the auxiliary wire dry elongation is 15mm, the main wire feeding speed is 10m / min, the auxiliary wire feeding speed is 0.2m / min, and the cold metal transfer arc is used as the heat source. The tip of the welding gun is The distance from the substrate was 15 mm, the welding gun was perpendicular to the workpiece, and single-pass reciprocating welding was performed layer by layer with the length direction of the magnesium alloy substrate as the printing direction. The welding current was 90 A, the welding voltage was 12 V, the welding speed was 0.3 m / min, the single-pass layer length was set to 12 cm, the single-layer weld height was 3 mm, the weld width was 7 mm, and the welding gun lifting height was 3.2 mm. After each welding, the oxide film on the surface of the printed part was cleaned and the next layer was welded again after the interlayer temperature reached a certain value. The interlayer cooling time was 5 min. 20 layers were stacked to obtain a magnesium alloy arc additive component.

[0064] Step 3: Perform short-time high-energy pulse treatment on the magnesium alloy arc additive component with a voltage of 3000V and a current density of 150A / mm 2 , duty cycle 40%, frequency 20 Hz, processing time 3 s, and then laser shock peening with an energy density of 10 J / cm 2 , pulse width 8ns, impact number 3 times, and magnesium alloy arc additive product was obtained.

[0065] According to the ISO 6892-1-2009 standard test method, three vertical (parallel to the BD) and horizontal (perpendicular to the BD) tensile test specimens were prepared by wire electrode cutting. Yield strength and tensile strength tests were carried out using a C45.105 universal tensile testing machine parallel to the BD and perpendicular to the BD tensile section. The test speed was 1 mm / min and the tensile tests were performed at room temperature (25°C).

[0066] After testing, its room temperature yield strength is 218MPa, tensile strength is 364MPa, and elongation is 18.5%.

[0067] Example 3

[0068] A high-strength and high-plasticity rare earth magnesium alloy material comprises the following components by weight: Al 12%, Nd 2.52%, Sm 3.78%, Zn 0.77%, Zr 0.48%, Ca 0.14%, Mn 0.35%, and the balance being magnesium and unavoidable impurities.

[0069] The specific preparation process of the above-mentioned high-strength and high-plasticity rare earth magnesium alloy material is as follows:

[0070] Step 1: Prepare a cored wire according to the above process, wherein the cored wire comprises the following components by weight: Al 43.4%, Nd 10%, Sm 15%, Zn 0.1%, ZrO2 8%, CaCO3 2%, and the balance being magnesium and unavoidable impurities;

[0071] Step 2: Fix the pretreated AZ31B magnesium alloy substrate on the printing table, feed the AZ31B magnesium alloy welding wire under the welding gun, and bypass the auxiliary flux-cored filling wire so that the two welding wires are in the same plane, the main wire is perpendicular to the horizontal workbench, adjust the angle between the main wire and the auxiliary wire to 55° and make the ends of their axes intersect at one point, and feed them by two wire feeders. The main wire dry elongation is 14mm, the auxiliary wire dry elongation is 9mm, the main wire feeding speed is 12m / min, the auxiliary wire feeding speed is 0.5m / min, and the cold metal transfer arc is used as the heat source. The distance between the welding gun tip and the welding gun tip is 100mm. The welding gun was perpendicular to the workpiece and the length direction of the magnesium alloy substrate was used as the printing direction for single-pass reciprocating welding. The welding current was 150A, the welding voltage was 20V, the welding speed was 0.7m / min, the single-pass length was set to 12cm, the single-layer weld height was 3mm, the weld width was 7mm, and the welding gun lifting height was 3.2mm. After each welding, the oxide film on the surface of the printed part was cleaned and the next layer was welded again after the interlayer temperature reached a certain value. The interlayer cooling time was 5min. 20 layers were stacked to obtain a magnesium alloy arc additive component.

[0072] Step 3: Perform short-time high-energy pulse treatment on the magnesium alloy arc additive component with a voltage of 3500V and a current density of 250A / mm 2 , duty cycle 30%, frequency 50 Hz, processing time 0.5 s, and then laser shock peening with an energy density of 12 J / cm 2 , pulse width 9ns, impact number 1, and magnesium alloy arc additive product was obtained.

[0073] According to the ISO 6892-1-2009 standard test method, three vertical (parallel to the BD) and horizontal (perpendicular to the BD) tensile test specimens were prepared by wire electrode cutting. Yield strength and tensile strength tests were carried out using a C45.105 universal tensile testing machine parallel to the BD and perpendicular to the BD tensile section. The test speed was 1 mm / min and the tensile tests were performed at room temperature (25°C).

[0074] After testing, its room temperature yield strength is 225MPa, tensile strength is 372MPa, and elongation is 19%.

[0075] Comparative Example 1

[0076] This comparative example provides a rare earth magnesium alloy material, which differs from Example 1 only in that the microalloying elements Zr and Ca are not added, and the post-treatment adopts a solid solution aging heat treatment process. The specific steps are as follows:

[0077] Step 1: Prepare a cored wire according to the above process, wherein the cored wire comprises the following components by weight: Al 42.1%, Nd 30%, Sm 10%, Zn 0.1%, and the balance being magnesium and unavoidable impurities;

[0078] Step 2: Fix the pretreated AZ31B magnesium alloy substrate on the printing table, feed the AZ31B magnesium alloy welding wire under the welding gun, and bypass the auxiliary flux-cored filling wire so that the two welding wires are in the same plane, the main wire is perpendicular to the horizontal workbench, adjust the angle between the main wire and the auxiliary wire to 75° and make the ends of their axes intersect at one point, and feed them by two wire feeders. The main wire dry elongation is 10mm, the auxiliary wire dry elongation is 10mm, the main wire feeding speed is 8.5m / min, the auxiliary wire feeding speed is 0.4m / min, and the cold metal transfer arc is used as the heat source. The tip of the welding gun is The distance from the substrate was 10 mm, the welding gun was perpendicular to the workpiece, and single-pass reciprocating welding was performed layer by layer with the length direction of the magnesium alloy substrate as the printing direction. The welding current was 100 A, the welding voltage was 15 V, the welding speed was 0.5 m / min, the single-pass layer length was set to 12 cm, the single-layer weld height was 3 mm, the weld width was 7 mm, and the welding gun lifting height was 3.2 mm. After each welding, the oxide film on the surface of the printed part was cleaned and the next layer was welded again after waiting for the interlayer temperature to reach a certain value. The interlayer cooling time was 5 min. 15 layers were stacked to obtain a magnesium alloy arc additive component.

[0079] Step 3: Perform solution aging heat treatment on the magnesium alloy arc additive component, heat the magnesium alloy arc additive component to 525°C, keep it warm for 3 hours, water-cool it to room temperature, heat it to 200°C, keep it warm for 12 hours, and air-cool it to room temperature to obtain a magnesium alloy arc additive product.

[0080] According to the ISO 6892-1-2009 standard test method, three vertical (parallel to the BD) and horizontal (perpendicular to the BD) tensile test specimens were prepared by wire electrode cutting. Yield strength and tensile strength tests were carried out using a C45.105 universal tensile testing machine parallel to the BD and perpendicular to the BD tensile section. The test speed was 1 mm / min and the tensile tests were performed at room temperature (25°C).

[0081] After testing, its room temperature yield strength is 198MPa, tensile strength is 337MPa, and elongation is 14.2%.

[0082] Comparative Example 2

[0083] This comparative example provides a rare earth magnesium alloy material, which differs from Example 1 only in that no post-processing process is performed. The specific steps are as follows:

[0084] Step 1: Prepare a cored wire according to the above process, wherein the cored wire comprises the following components by weight: Al 42.1%, Nd 30%, Sm 10%, Zn 0.1%, ZrO2 4%, CaCO3 2%, and the balance being magnesium and unavoidable impurities;

[0085] Step 2: Fix the pretreated AZ31B magnesium alloy substrate on the printing table, feed the AZ31B magnesium alloy welding wire under the welding gun, and bypass the auxiliary flux-cored filling wire so that the two welding wires are in the same plane, the main wire is perpendicular to the horizontal workbench, adjust the angle between the main wire and the auxiliary wire to 75° and make the ends of their axes intersect at one point, and feed them by two wire feeders. The main wire dry elongation is 10mm, the auxiliary wire dry elongation is 10mm, the main wire feeding speed is 8.5m / min, the auxiliary wire feeding speed is 0.4m / min, and the cold metal transfer arc is used as the heat source. The tip of the welding gun is The distance from the substrate was 10 mm, the welding gun was perpendicular to the workpiece, and single-pass reciprocating welding was performed layer by layer with the length direction of the magnesium alloy substrate as the printing direction. The welding current was 100 A, the welding voltage was 15 V, the welding speed was 0.5 m / min, the single-pass layer length was set to 12 cm, the single-layer weld height was 3 mm, the weld width was 7 mm, and the welding gun lifting height was 3.2 mm. After each welding, the oxide film on the surface of the printed part was cleaned and the interlayer temperature was waited to reach a certain value before welding the next layer again. The interlayer cooling time was 5 min, and 15 layers were stacked to obtain a magnesium alloy arc additive component.

[0086] According to the ISO 6892-1-2009 standard test method, three vertical (parallel to the BD) and horizontal (perpendicular to the BD) tensile test specimens were prepared by wire electrode cutting. Yield strength and tensile strength tests were carried out using a C45.105 universal tensile testing machine parallel to the BD and perpendicular to the BD tensile section. The test speed was 1 mm / min and the tensile tests were performed at room temperature (25°C).

[0087] After testing, its room temperature yield strength is 190MPa, tensile strength is 325MPa, and elongation is 15%.

[0088] Comparative Example 3

[0089] This comparative example is a rare earth magnesium alloy material, which differs from Example 1 only in that Sm and Nb are replaced by Gd and Y, no Ca is added, and the post-treatment adopts solid solution aging treatment. The specific steps are as follows:

[0090] Step 1: Prepare a cored wire according to the above process, wherein the cored wire comprises the following components by weight: Al 40%, Gd 10%, Y 3%, Zr 0.5%, Zn 0.3%, and the balance being magnesium and unavoidable impurities;

[0091] Step 2: Fix the pretreated AZ31B magnesium alloy substrate on the printing table, feed the AZ31B magnesium alloy welding wire under the welding gun, and bypass the auxiliary flux-cored filling wire so that the two welding wires are in the same plane, the main wire is perpendicular to the horizontal workbench, adjust the angle between the main wire and the auxiliary wire to 75° and make the ends of their axes intersect at one point, and feed them by two wire feeders. The main wire dry elongation is 10mm, the auxiliary wire dry elongation is 10mm, the main wire feeding speed is 8.5m / min, the auxiliary wire feeding speed is 0.4m / min, and the cold metal transfer arc is used as the heat source. The tip of the welding gun is The distance from the substrate was 10 mm, the welding gun was perpendicular to the workpiece, and single-pass reciprocating welding was performed layer by layer with the length direction of the magnesium alloy substrate as the printing direction. The welding current was 100 A, the welding voltage was 15 V, the welding speed was 0.5 m / min, the single-pass layer length was set to 12 cm, the single-layer weld height was 3 mm, the weld width was 7 mm, and the welding gun lifting height was 3.2 mm. After each welding, the oxide film on the surface of the printed part was cleaned and the next layer was welded again after waiting for the interlayer temperature to reach a certain value. The interlayer cooling time was 5 min. 15 layers were stacked to obtain a magnesium alloy arc additive component.

[0092] Step 3: Perform solution aging heat treatment on the magnesium alloy arc additive component, heat the magnesium alloy arc additive component to 450°C, keep it warm for 2 hours, water-cool it to room temperature, heat it to 200°C and keep it warm for 80 hours, and air-cool it to room temperature to obtain a magnesium alloy arc additive product.

[0093] According to the ISO 6892-1-2009 standard test method, three vertical (parallel to the BD) and horizontal (perpendicular to the BD) tensile test specimens were prepared by wire electrode cutting. Yield strength and tensile strength tests were carried out using a C45.105 universal tensile testing machine parallel to the BD and perpendicular to the BD tensile section. The test speed was 1 mm / min and the tensile tests were performed at room temperature (25°C).

[0094] After testing, its room temperature yield strength is 200MPa, tensile strength is 340MPa, and elongation is 14%.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-strength and high-plasticity rare earth magnesium alloy material, characterized in that: The weight percentage of its components is: Al 6% to 12%, Nd 1% to 10%, Sm 1% to 6%, Zn 0.5% to 1.5%, Zr 0.1% to 0.5%, Ca 0.05% to 0.3%, Mn 0.1% to 1%, and the balance is magnesium and inevitable impurities.

2. An arc additive manufacturing process for a high-strength and high-plasticity rare earth magnesium alloy material according to claim 1, characterized in that: The following steps are involved: S1. Prepare a cored wire containing Nd, Sm, Zr and Ca; the cored wire comprises a Mg-Al alloy sheath and a core powder, wherein the core powder comprises Nd powder, Sm powder, ZrO2 powder and CaCO3 powder; S2. Using AZ31B magnesium alloy as the main wire, the flux-cored filler wire as the auxiliary wire, and the Mg alloy plate as the substrate, a double-wire arc additive manufacturing device is used to perform additive manufacturing to obtain an additively manufactured workpiece; S3. Subjecting the additively manufactured workpiece to high-energy gradient pulse processing and laser shock processing in sequence to obtain a high-strength and high-plasticity rare earth magnesium alloy material.

3. The arc additive manufacturing process for high-strength and high-plasticity rare earth magnesium alloy material according to claim 2, characterized in that: The core filling wire includes the following components in weight percentage: Nd powder 5% to 35%, Sm powder 1% to 20%, ZrO2 powder 1% to 10%, CaCO3 powder 1% to 10%, AZ31B magnesium alloy powder 0% to 10%, and the balance is Al-Mg alloy outer skin; wherein, the mass ratio of ZrO2 powder to CaCO3 powder is not less than 5:3, and the total mass is 5% to 10% of the total mass of the core filling wire; the core powder accounts for 40% to 50% of the total mass of the core filling wire.

4. The arc additive manufacturing process for high-strength and high-plasticity rare earth magnesium alloy material according to claim 2, characterized in that: The core medicine powder has a particle size of 15 μm to 50 μm; and / or The diameter of the core filling wire is 3mm to 5mm.

5. The arc additive manufacturing process for high-strength and high-plasticity rare earth magnesium alloy material according to claim 2, characterized in that: In S2, the welding current of the additive manufacturing is 90A to 150A, the welding voltage is 12V to 20V, the welding speed is 0.3m / min to 0.7m / min, and the height of the welding gun from the substrate is 8mm to 15mm.

6. The arc additive manufacturing process for high-strength and high-plasticity rare earth magnesium alloy material according to claim 2, characterized in that: In S2, the angle between the main wire and the auxiliary wire is 30° to 80°, and the main wire is perpendicular to the horizontal workbench; and / or In S2, the main arc-starting wire has a stem extension of 10 mm to 14 mm, and the bypass auxiliary wire has a stem extension of 9 mm to 15 mm.

7. The arc additive manufacturing process for high-strength and high-plasticity rare earth magnesium alloy material according to claim 2, characterized in that: In S2, the wire feeding speed of the main wire is 6m / min to 12m / min, the wire feeding speed of the auxiliary wire is 0.2m / min to 3m / min, and the wire feeding speed ratio of the main wire to the auxiliary wire is (5 to 50):

1.

8. The arc additive manufacturing process for high-strength and high-plasticity rare earth magnesium alloy material according to claim 2, characterized in that: In S3, the voltage of the high energy gradient pulse treatment is 3000V to 4000V, and the current density is 150A / mm 2 ~250A / mm 2 , the duty cycle is 30% to 40%, the frequency is 20Hz to 50Hz, and the processing time is 0.5s to 3s.

9. The arc additive manufacturing process for high-strength and high-plasticity rare earth magnesium alloy material according to claim 2, characterized in that: In S3, the energy density of the laser shock treatment is 8 J / cm 2 ~12J / cm 2 , the pulse width is 8ns~10ns, and the number of impacts is 1~3 times.

10. Application of the high-strength and high-plasticity rare earth magnesium alloy material according to claim 1 in the fields of automobiles, aerospace, military industry or electronic communications.