A laser assisted thermoforming coupling multi-path wire feeding auxiliary alloy additive manufacturing method

Abstract

The application provides a laser auxiliary thermoforming coupling multi-path wire feeding auxiliary alloy additive manufacturing method, belongs to the field of alloy additive manufacturing, has the characteristics of high efficiency, flexibility, safety and the like, is a short process manufacturing technology for large-scale complex metal components, and can meet the requirements of the fields of traffic equipment, aerospace and the like. The existing magnesium alloy and aluminum alloy additive manufacturing is faced with the problems of difficulty in component regulation and control, large roughness, low forming precision and the like, the laser auxiliary thermoforming coupling multi-path wire feeding auxiliary alloy additive manufacturing method is adopted, parameters such as relevant processes, welding wires, main path and bypass wire speed, current, voltage and laser irradiation are adjusted according to the to-be-processed components and component proportions, the additive manufacturing of magnesium alloy and aluminum alloy is better realized, the component flexible regulation and control is realized, the forming precision is improved, the grain size is refined, the grain size is less than or equal to 45 mu m, the anisotropy difference rate of alloy mechanical properties is less than 5%, meanwhile, the production cost is reduced, and the method is suitable for industrialized production.

Description

Technical Field

[0001] This invention belongs to the field of alloy additive manufacturing, specifically relating to a laser-assisted thermoforming coupled multi-path wire feeding assisted alloy additive manufacturing method. Background Technology

[0002] With the development of transportation equipment, aerospace and other fields, the demand for large-scale, integrated and complex manufacturing of products is increasing, while higher requirements are being placed on material performance. Traditional casting, forging and welding processes are difficult to meet the current requirements for high-efficiency, low-cost precision machining of non-standard shaped parts, different sizes and high-strength materials.

[0003] Unlike traditional manufacturing, additive manufacturing offers high flexibility and has attracted widespread attention. Currently, the main additive manufacturing methods include selective laser melting, electron beam melting, and arc welding, all of which have been widely adopted. However, they also face several challenges: difficulty in controlling composition, high surface roughness, large grain size, difficulty in achieving uniform distribution of alloy composition and grain size within each layer and between layers, low forming accuracy, high molten pool temperature during additive manufacturing, and rapid cooling rates, resulting in a non-equilibrium process that makes defect suppression difficult. Furthermore, the technical bottleneck of achieving adjustable and controllable alloy composition in actual industrial production makes it difficult to meet the precision machining requirements of complex components with non-standard shapes and controllable dimensions. Additionally, during additive manufacturing welding, welding high-strength alloys into wires is difficult, uneven, and prone to wire breakage. Therefore, how to improve the forming accuracy of alloy additive manufacturing, reduce roughness, reduce wire breakage, refine grain size, achieve uniform distribution of alloy composition and grain size in each layer and between layers, and suppress defects, so as to realize the production of precision-machined profiles of any shape and size alloys and high-strength alloys, is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] To address the aforementioned technical challenges, this invention provides a laser-assisted thermal shaping coupled multi-path wire feeding assisted alloy additive manufacturing method, which mainly includes the following steps:

[0005] The main guide wire is one or any combination of AZ series magnesium alloy, Mg-rare earth (RE) series magnesium alloy, 7075 series aluminum alloy, 6061 series aluminum alloy, 5356 series aluminum alloy, 4220 series aluminum alloy, 4043 series aluminum alloy, 2319 series aluminum alloy, Al-Mg series aluminum alloy, and Al-Cu-Mg series aluminum alloy, with a diameter of 0.8-1.6mm;

[0006] The bypass wire is one or any combination of AZ-based magnesium alloy, Al-TiC composite material, Al-SiC composite material, pure Al or pure Mg, with a diameter of 0.6-2.0 mm;

[0007] (1) Polish the substrate clean to remove the surface oxide scale, clean it with anhydrous ethanol, and then dry it for later use; the substrate is either a magnesium alloy or an aluminum alloy.

[0008] (2) Preheating the substrate: Heat the substrate to 50-200℃ and fix the preheated substrate on the worktable with a clamp;

[0009] (3) Adjust the position of the robotic arm. The main wire is perpendicular to the substrate. The bypass wire can be single or multiple. The angle between the bypass wire and the main wire is 20-70°. The main wire extension is 10-16mm and the bypass wire extension is 15-17mm.

[0010] (4) Use a cold metal transfer welding power supply coupled with a fiber laser to perform arc initiation additive manufacturing of 5-30 layers, wherein the current is 72-180A, the voltage is 10-25V, the main wire speed is 3.5-6.0m / min, the bypass wire speed is 0.1-0.8m / min, the welding speed is 3-7mm / s, and the fiber laser has the following characteristics: laser power is 300-2000W, frequency is 200-5000Hz, wavelength is 1080nm, and the temperature of each arc initiation additive manufacturing layer is 90-150℃.

[0011] (5) After the additive manufacturing is completed, an alloy profile is obtained by scanning with a fiber laser for 2-20 seconds. The alloy profile is either an aluminum alloy or a magnesium alloy, wherein the alloy grain size is ≤45μm and the anisotropy difference rate of the alloy mechanical properties is <5%. The fiber laser has a laser power of 300-2000W, a frequency of 200-5000Hz, and a wavelength of 1080nm.

[0012] Furthermore, the main circuit wire is: AZ31, Mg-6Al-1.2Zn-0.8Mn-1.5SiC or Al-4Cu-1.2Mg-0.5Si-0.3Mn-0.5Zn.

[0013] Furthermore, the bypass wires are: AZ91, Al-8.5TiC composite material, and Al-3.5SiC composite material.

[0014] Furthermore, the laser power in step (4) is 400-1500W and the frequency is 500-2000Hz.

[0015] Compared with the prior art, the advantages of the present invention are:

[0016] Compared with existing technologies, this invention, based on the composition and proportion of the raw material wire, achieves the following significant results through the synergistic control of the process and related process parameters: First, it breaks through the technical bottlenecks of existing technologies, such as difficulty in obtaining high-strength aluminum or magnesium alloy wires, wire breakage, and difficulty in manufacturing irregularly shaped and sized profiles. Furthermore, the composition of alloys after additive manufacturing in existing technologies is mainly consistent with the raw alloy material, making it difficult to change the alloy's composition, proportion, and mechanical properties through additive manufacturing. In contrast, this invention can simultaneously perform single-path or multi-path additive manufacturing, combined with the synergistic control of the process and related process parameters. The synergistic regulation of parameters enables the adjustable and controllable composition, mass ratio, and mechanical properties of the alloy after additive manufacturing. This breaks through the technical bottleneck of existing technologies where alloy composition control relies entirely on the constraints of the original wire material. Simultaneously, it achieves additive manufacturing of high-strength aluminum or magnesium alloys with irregular shapes, controllable dimensions, and adjustable and controllable composition and mechanical properties. Secondly, while existing technologies mainly target single-component additive manufacturing, this invention can achieve multi-path additive manufacturing of alloys with the same composition (same or different diameters) and alloys with multiple different compositions (same or different diameters). Thirdly, existing additive manufacturing technologies suffer from edge effects, leading to issues such as wire breakage, difficulty in achieving uniform grain size distribution (e.g., alloy composition and equiaxed grain size) across layers and between layers, and consequently, larger grain sizes. This results in higher alloy roughness and the formation of micropores and cracks on the surface. In contrast, this invention achieves uniform distribution of alloy composition and grain size across layers and between layers, resulting in finer and more uniform grain sizes than existing technologies. Specifically, the average grain size is controlled to ≤45μm, and the alloy surface roughness is low, resulting in a smooth alloy surface after additive manufacturing. First, it has no microscopic pores or cracks; second, existing technologies in additive manufacturing result in a high anisotropy rate of mechanical properties in the final profiles, generally 30% or higher. The anisotropy rate of mechanical properties obtained by this invention is far lower than that of existing technologies, controllable to within 5%. Furthermore, for alloys of the same composition, the tensile strength of the profiles obtained by this invention, both perpendicular and parallel to the travel direction, is higher than the corresponding tensile strengths obtained by existing technologies. This allows for the simultaneous realization of high-strength alloy additive manufacturing, addressing both processes that can and cannot be processed by existing technologies. Detailed analysis follows:

[0017] 1. Compared with the prior art, the present invention can control the alloy composition in the additive manufacturing process by synergistically regulating the composition and ratio of the raw material filaments and the relevant process parameters, thereby simplifying the process, reducing the preparation cost, and realizing short-process processing. It breaks the constraint that the composition control in the additive manufacturing process depends on the original filament composition. According to actual needs, it realizes the adjustable and controllable composition, content, and arbitrary size or shape of filaments or profiles in the additive manufacturing process.

[0018] 2. Due to the high molten pool temperature and severe grain coarsening during existing additive manufacturing processes, coupled with rapid cooling rates, this process is non-equilibrium and presents significant challenges in microstructure control. This invention, however, effectively controls the molten pool temperature during non-equilibrium solidification, preventing excessive evaporation of the alloy during additive manufacturing. It controls the non-equilibrium solidification microstructure, achieving grain refinement and preventing performance degradation caused by coarse grains under multiple thermal cycles. Compared to existing technologies for processing the same alloy, this invention yields finer and more uniform grain sizes, particularly equiaxed grains, effectively improving the alloy's thermal stability and mechanical properties. Furthermore, this invention enables in-situ heat treatment and remelting / shaping, reducing residual stress and minimizing element segregation during non-equilibrium solidification. Simultaneously, it facilitates the redistribution of solute atoms within the alloy, achieving elemental solidification and second-phase precipitation, refining the second phase, and significantly improving alloy forming accuracy. Ultimately, it achieves uniform composition and eliminates macroscopic and microscopic pore defects. Attached Figure Description

[0019] Figure 1 This is a diagram showing the relative positions of the fiber laser, robotic arm, main path wire, and bypass wire in Example 1. Detailed implementation method:

[0020] Example 1:

[0021] The main wire is AZ31 (composition by mass): Al 3.0%, Zn 1.0%, Mn 0.5%, trace impurities ≤0.02%, the remainder is magnesium, and the diameter is 0.8mm;

[0022] The bypass wire is Al (99.8 wt.%) with a diameter of 0.8 mm;

[0023] (1) Select a magnesium alloy substrate, grind the substrate clean, remove the surface oxide scale, clean it with anhydrous ethanol and dry it for later use.

[0024] (2) Preheating the substrate: Heat the substrate to 160°C and fix the preheated substrate on the worktable with a clamp.

[0025] (3) Adjust the position of the robotic arm so that the main wire is perpendicular to the substrate and the angle between the bypass wire and the main wire is 65°. Adjust the extension of the main wire to 10mm and the extension of the bypass wire to 15mm. The relative positions of the fiber laser, robotic arm, main wire, and bypass wire are shown in the figure below. Figure 1 As shown;

[0026] (4) Use a cold metal transfer welding power supply coupled with a fiber laser to perform arc-starting additive manufacturing of 15-18 layers, wherein the current is 72A, the voltage is 10.2V, the main wire speed is 3.8m / min, the bypass wire speed is 0.5m / min, the welding speed is 7mm / s, the laser power is 500W, the frequency is 2000Hz, the wavelength is 1080nm, and the temperature of each arc-starting additive manufacturing layer is ~150℃;

[0027] (5) After the additive manufacturing is completed, a fiber laser is used to scan for 5-10s to obtain a Mg-7.5Al-0.8Zn-0.3Mn profile. The laser power is 500W, the frequency is 500Hz, and the wavelength is 1080nm. The composition of the profile is tested. According to the mass percentage: Al: 7.5%, Zn: 0.8%, Mn: 0.3%, trace impurity elements ≤0.02%, and the balance is Mg. The average grain size is ~45μm, achieving uniform distribution of alloy composition and grain size in each layer and between layers. The roughness is small, and the alloy surface has good smoothness after additive manufacturing. There are no micropores and cracks. The tensile strength of the profile perpendicular to the direction of travel is 310MPa, and the tensile strength parallel to the direction of travel is 295MPa. The anisotropy difference rate of mechanical properties is only ~4.8%, which is much smaller than the anisotropy difference rate of profiles obtained by existing technologies. Therefore, the mechanical properties of the material obtained in Example 1 are better than those of profiles obtained by existing technologies.

[0028] Example 2: The main wire is an Al-Cu-Mg aluminum alloy (composition by mass ratio): Cu 4.0%, Mg 1.2%, Si 0.5%, Mn 0.3%, Zn 0.5%, trace impurity elements ≤0.02%, the remainder is Al, and the diameter is 1.6mm;

[0029] Bypass 1 wire is AZ91 (composition by mass): Al 9.0%, Zn 1.4%, Mn 0.5%, trace impurities ≤0.02%, the remainder is magnesium, and the diameter is 1.6mm;

[0030] Bypass 2 wire is Al-TiC (composition by mass ratio): TiC 8.5%, trace impurities ≤0.02%, the remainder is Al, and the diameter is 2.0mm;

[0031] (1) Select an aluminum alloy substrate, grind the substrate clean, remove the surface oxide scale, clean it with anhydrous ethanol and dry it for later use.

[0032] (2) Preheating the substrate: Heat the substrate to 60°C and fix the preheated substrate on the worktable with a clamp.

[0033] (3) Adjust the position of the robotic arm so that the main wire is perpendicular to the substrate, and the bypass wire 1 and bypass wire 2 are both located on the same side of the main wire. The angle between bypass wire 1 and the main wire is 29°, and the angle between bypass wire 2 and the main wire is 50°. Adjust the extension length of the main wire to 15mm, the extension length of bypass wire 1 to 16mm, and the extension length of bypass wire 2 to 17mm.

[0034] (4) Use a cold metal transfer welding power supply coupled with a fiber laser to perform arc-starting additive manufacturing of 16-20 layers, wherein the current is 180A, the voltage is 23V, the main wire speed is 6.0m / min, the bypass wire 1 speed is 0.3m / min, the bypass wire 2 speed is 0.1m / min, the welding speed is 3mm / s, the laser power is 1000W, the frequency is 500Hz, the wavelength is 1080nm, and the temperature of each arc-starting additive manufacturing layer is ~90℃;

[0035] (5) After the additive manufacturing is completed, a fiber laser is used to scan for 6-8s to obtain an Al-3.8Cu-3.5Mg-1.0TiC-0.6Zn-0.4Si-0.4Mn profile. The laser power is 1500W, the frequency is 1200Hz, and the wavelength is 1080nm. The composition of the profile is tested. According to the mass percentage: Cu 3.8%, Mg 3.5%, TiC 1.0%, Zn 0.6%, Si 0.4%, Mn 0.4%, trace impurity elements ≤0.02%, and the balance is Al. The average grain size is ~23μm, and the anisotropy difference rate of mechanical properties is <5%, which is much smaller than the anisotropy difference rate of profiles obtained by existing technologies. The uniform distribution of alloy composition and grain size of each layer and interlayer is achieved, the roughness is small, the surface finish of the alloy after additive manufacturing is good, and there are no micropores and cracks. The mechanical properties of the obtained material are better than those of profiles obtained by existing technologies.

[0036] Example 3:

[0037] The main wire is an AZ-based magnesium alloy (composition by mass): Al 6.0%, Zn 1.2%, Mn 0.8%, SiC 1.5%, trace impurities ≤0.02%, the remainder is magnesium, and the diameter is 2.0 mm;

[0038] The bypass wire is Al (99.8 wt.%) with a diameter of 1.0 mm;

[0039] (1) Select a magnesium alloy substrate, grind the substrate clean, remove the surface oxide scale, clean it with anhydrous ethanol and dry it for later use.

[0040] (2) Preheating the substrate: Heat the substrate to 100°C and fix the preheated substrate on the worktable with a clamp.

[0041] (3) Adjust the position of the robotic arm so that the main wire is perpendicular to the substrate and the angle between the bypass wire and the main wire is 65°. Adjust the extension length of the main wire to 10mm and the extension length of the bypass wire to 16mm.

[0042] (4) Use a cold metal transfer welding power supply coupled with a fiber laser to perform arc initiation additive manufacturing of 18-20 layers, wherein the current is 90A, the voltage is 11.5V, the main wire speed is 3.5m / min, the bypass wire speed is 0.3m / min, the welding speed is 3.5mm / s, the laser power is 2000W, the frequency is 5kHz, the wavelength is 1080nm, and the temperature of each arc initiation additive manufacturing layer is ~160℃;

[0043] (5) After additive manufacturing is completed, a fiber laser is used to scan for 5-10 seconds to obtain a Mg-8.1Al-0.8Zn-0.5Mn-0.9SiC profile. The laser power is 700W, the frequency is 800Hz, and the wavelength is 1080nm. The composition of the profile is tested and, by mass percentage, is: Al: 8.1%, Zn: 0.8%, Mn: 0.5%, SiC: 0.9%, trace impurity elements ≤0.02%, and the balance is Mg. The average grain size is ~2. The material has a particle size of 0 μm, achieving a uniform distribution of alloy composition and grain size in each layer and between layers. It has low roughness, resulting in a smooth alloy surface after additive manufacturing, free from micropores and cracks. The tensile strength of the profile perpendicular to the travel direction is 314 MPa, and the tensile strength parallel to the travel direction is 300 MPa. The anisotropy difference rate of mechanical properties is only ~4.5%, which is much lower than the anisotropy difference rate of mechanical properties of profiles obtained by existing technologies. Therefore, the mechanical properties of the material obtained in Example 3 are superior to those of profiles obtained by existing technologies.

[0044] Comparative Example 1

[0045] The paper by Yihang Yang et al., “Wire arc additive manufacturing of a novel ATZM31 magnesium alloy: Microstructure evolution and mechanical properties,” discloses the preparation of a Mg-2.6Al-0.7Sn-0.6Zn-0.5Mn-0.01Y (wt.%) magnesium alloy using a cold metal transfer welding power source and a single-path wire with a diameter of 1.2 mm. The welding speed was 10 mm / s, the wire feed speed was 12.3 m / min, the tensile strength of the alloy parallel to the direction of travel was 211 MPa, the tensile strength perpendicular to the direction of travel was 94 MPa, and the anisotropy rate of the alloy was 55%. The anisotropy rate (55%) of the alloy after additive manufacturing is much higher than that of the alloy obtained in this invention (<5%). In addition, the tensile strength in both directions is lower than that in the two directions of this invention.

[0046] In summary, compared with existing technologies, this invention, based on the composition and proportion of the raw material wire, and through the synergistic control of the process and related process parameters, achieves the following significant results: First, it breaks through the technical bottleneck of existing technologies in obtaining high-strength aluminum alloy or magnesium alloy wires and additive manufacturing of irregularly shaped and controllable-size profiles. Specifically, it effectively solves the technical problems of difficulty in preparing high-strength aluminum alloy or magnesium alloy wires and wire breakage, as well as the difficulty of existing technologies mainly achieving additive manufacturing of regular-shaped or small-sized profiles, and the difficulty in achieving additive manufacturing of irregularly shaped or large-sized profiles. Second, existing technologies mainly target single-component additive manufacturing, while this invention can achieve multi-path additive manufacturing of alloys with the same composition (same diameter or different diameters) and multiple alloys with different compositions (same diameter or different diameters). By selecting fine wire materials with fixed composition and moderate strength, it can additively manufacture profiles with adjustable composition, strength, and shape, enabling adjustable and controllable profile composition, structure, and performance according to the actual working conditions of the alloy application. Third, in the additive manufacturing process, due to… The marginal effect makes it difficult to achieve uniform distribution of alloy composition and grain size in each layer and between layers, resulting in high roughness. After additive manufacturing, the alloy surface is prone to micropores, cracks, and wire breakage. However, this invention can achieve uniform distribution of alloy composition and grain size in each layer and between layers, with finer grains and an average grain size controlled at ≤45μm. The roughness is small, resulting in a smooth alloy surface after additive manufacturing, free from micropores and cracks, and better avoiding wire breakage. Fourth, existing technologies have difficulty achieving uniform distribution of fine grains in the additive manufacturing process. Furthermore, the anisotropy difference rate of the mechanical properties of the final obtained profile is relatively high, generally 30% or more. However, the present invention can achieve a profile with smaller and more uniform grain size than the prior art, while the anisotropy difference rate of the mechanical properties of the profile is much lower than that of the prior art, and can be controlled below 5%. Moreover, for the same alloy, the tensile strength of the profile obtained by the present invention along the direction perpendicular to the travel direction and the tensile strength along the direction parallel to the travel direction are higher than the corresponding tensile strengths obtained by the prior art, thus better realizing the additive manufacturing of high-strength alloys.

Claims

1. A laser-assisted thermal shaping coupled multi-path wire feeding assisted alloy additive manufacturing method, characterized in that, It mainly includes the following methods and steps: The main guide wire is one or any combination of AZ31, Mg-6Al-1.2Zn-0.8Mn-1.5SiC or Al-4Cu-1.2Mg-0.5Si-0.3Mn-0.5Zn, with a diameter of 0.8-1.6mm; The bypass wire is one or any combination of AZ91, Al-8.5TiC composite material, and Al-3.5SiC composite material, with a diameter of 0.6-2.0 mm; (1) Polish the substrate clean, remove the surface oxide scale, clean it with anhydrous ethanol and dry it for later use; the substrate is either a magnesium alloy or an aluminum alloy. (2) Preheating the substrate: Heat the substrate to 50-200℃ and fix the preheated substrate on the worktable with a clamp; (3) Adjust the position of the robotic arm. The main wire is perpendicular to the substrate. The bypass wire can be single or multiple. The angle between the bypass wire and the main wire is 20-70°. The main wire extension is 10-16mm and the bypass wire extension is 15-17mm. (4) Use a cold metal transfer welding power supply coupled with a fiber laser to perform arc initiation additive manufacturing of 5-30 layers, wherein the current is 72-180A, the voltage is 10-25V, the main wire speed is 3.5-6.0m / min, the bypass wire speed is 0.1-0.8m / min, the welding speed is 3-7mm / s, and the fiber laser has a laser power of 300-2000W, a frequency of 200-5000Hz, a wavelength of 1080nm, and the temperature of each arc initiation additive manufacturing layer is 90-150℃; (5) After the additive manufacturing is completed, an alloy profile is obtained by scanning with a fiber laser for 2-20 seconds. The alloy profile is either an aluminum alloy or a magnesium alloy, wherein the alloy grain size is ≤45μm and the anisotropy difference rate of the alloy mechanical properties is <5%. The fiber laser has a laser power of 300-2000W, a frequency of 200-5000Hz, and a wavelength of 1080nm.

2. The laser-assisted thermoforming coupled multi-path wire feeding assisted alloy additive manufacturing method according to claim 1, characterized in that, The laser power in step (4) is 400-1500W and the frequency is 500-2000Hz.

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