A magnesium alloy laser-mig hybrid cold wire filling composite additive manufacturing method
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2026-04-08
- Publication Date
- 2026-06-09
Smart Images
Figure CN122165044A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of metal additive manufacturing technology, and in particular to a method for laser-MIG bypass cold filament filling composite additive manufacturing of magnesium alloys. Background Technology
[0002] Magnesium alloys are currently the lowest density metallic structural materials used in industrial applications (density 1.74~1.85 g / cm³). 3 It has outstanding advantages such as high specific strength and specific stiffness, excellent damping and vibration reduction performance, and strong recyclability, and has irreplaceable application prospects in aerospace, automotive lightweighting, high-end electronic equipment and other fields.
[0003] Additive manufacturing technology (also known as 3D printing technology) has the core advantage of "layer-by-layer manufacturing and accumulation" to achieve rapid prototyping of complex structural components without the need for complex molds. It effectively solves the technical problems of high forming difficulty, high mold cost, cumbersome process and low material utilization in the traditional magnesium alloy component manufacturing, and has become an important development direction for high-end manufacturing of magnesium alloy components.
[0004] Currently, the commonly used processes for magnesium alloy additive manufacturing are mainly divided into two categories: single laser additive manufacturing and single MIG arc additive manufacturing. However, both processes have significant technical bottlenecks, making it difficult to balance forming efficiency, forming quality, and mechanical properties. Among them, single MIG arc additive manufacturing is widely used in batch additive manufacturing due to its advantages of low equipment cost, convenient operation, and continuous wire feeding. However, its core drawbacks are: the arc heat input is relatively concentrated and difficult to control precisely; magnesium alloys have low melting points and are chemically active, which easily leads to problems such as poor molten pool stability and incomplete forming. At the same time, it is prone to defects such as porosity, slag inclusions, and hot cracks, resulting in limited component density and mechanical properties. In order to ensure forming quality, it is necessary to control the wire feeding speed and welding speed at a low level, resulting in low forming efficiency and serious oxidation loss.
[0005] Single-laser additive manufacturing processes often employ high-power continuous lasers. While they offer advantages such as concentrated energy, high forming accuracy, and a small heat-affected zone, enabling the formation of high-precision components, they suffer from low energy utilization, high equipment costs, limited single-pass layer filling, and low forming efficiency. Furthermore, magnesium alloys are prone to severe oxidation under high-power laser irradiation, resulting in oxide films that are difficult to remove and easily lead to defects such as porosity and inclusions. Simultaneously, the short melt pool time and concentrated heat input during high-power laser additive manufacturing can easily cause component deformation and hot cracking, resulting in incomplete metallurgical reactions and limited improvement in component mechanical properties, failing to meet the manufacturing demands of high-end fields for efficient and high-performance magnesium alloy components. Low-power pulsed lasers, with their advantages of gentle preheating, easily controllable heat input, and good oxidation suppression, are gradually being applied in the field of metal additive manufacturing. However, single-low-power pulsed laser additive manufacturing suffers from drawbacks such as low filling efficiency and slow forming speed, hindering its large-scale application.
[0006] Existing composite additive manufacturing technologies mostly employ high-power laser-MIG hybrid heat sources, but the challenge of balancing material deposition efficiency and energy utilization remains. Some dual-wire additive manufacturing technologies use dissimilar metal wires or complex hybrid heat sources. Dissimilar wire filling can easily lead to uneven interfacial metallurgical reactions, resulting in deteriorated metallurgical bonding performance and defects such as interfacial cracks and inclusions. Complex hybrid heat sources, on the other hand, suffer from complex equipment structures, high manufacturing costs, and operational difficulties, hindering large-scale engineering applications. Currently, there are no mature reports or industrial applications of additive manufacturing technology for magnesium alloys using a low-power pulsed laser-MIG hybrid heat source and co-source bypass cold wire synergistic filling. Therefore, there is an urgent need to develop a novel composite additive manufacturing process to overcome the inherent shortcomings of existing technologies. Summary of the Invention
[0007] To address the aforementioned problems, the present invention aims to provide a magnesium alloy laser-MIG bypass cold filament filling composite additive manufacturing method. This method utilizes the synergistic effect of a low-power pulsed laser and a MIG composite heat source, supplementary filling with co-source cold filaments, and precise control of process parameters. It effectively solves the problems of numerous defects, low forming efficiency, poor mechanical properties, and insufficient energy utilization inherent in single additive manufacturing processes. This improves the forming quality, density, and mechanical properties of components while reducing manufacturing costs, thus meeting the manufacturing needs of high-performance magnesium alloy complex components in high-end fields such as aerospace and automotive lightweighting.
[0008] The technical solution adopted in this invention is as follows:
[0009] The present invention proposes a method for laser-MIG bypass cold-filament filled composite additive manufacturing of magnesium alloys, comprising the following steps: S1. Select magnesium alloy sheet as the base material, which is similar in composition to MIG main welding wire and bypass cold wire, and pre-treat the surface of the base material. S2. Build a low-power pulsed laser-MIG bypass cold wire filler composite additive manufacturing system: Load the magnesium alloy MIG main welding wire into the MIG welding torch wire feeding mechanism, load the magnesium alloy cold wire into the bypass wire feeding mechanism, adjust the relative positions of the low-power pulsed laser generator, MIG welding torch and bypass wire feeding nozzle to ensure that the low-power pulsed laser, MIG arc and cold wire delivery trajectory are precisely matched, and the cold wire can be accurately fed into the edge of the molten pool; S3. Inert mixed gas is introduced into the additive forming area, and the flow rate of the protective gas is controlled; S4. Layered Additive Manufacturing: Simultaneously start the low-power pulsed laser generator and MIG power supply, set and calibrate the pulsed laser parameters and MIG welding parameters; the low-power pulsed laser acts on the substrate surface to achieve gentle preheating, while assisting in the formation of a stable molten pool; the MIG arc melts the magnesium alloy main welding wire to form a uniform molten pool; simultaneously start the bypass wire feeding mechanism to feed the magnesium alloy cold wire into the edge of the molten pool at a uniform speed; the cold wire relies on the residual heat of the molten pool formed by the synergistic effect of the low-power pulsed laser and the MIG arc to achieve rapid and uniform fusion filling; S5. Post-processing: After additive forming is completed, the component is subjected to stress-relief annealing to eliminate residual internal stress generated during the additive process; then the surface of the component is trimmed to ensure that the surface flatness and dimensional accuracy of the component meet the standards.
[0010] Furthermore, the MIG main welding wire and the bypass cold wire are made of the same magnesium alloy with completely identical chemical composition and mass fraction. The material is selected from AZ31 or AZ80 series, with Al content of 2.5%~4.0%, Zn content of 0.5%~1.0%, Mn content of 0.2%~0.5%, and the remainder being Mg matrix and unavoidable trace impurities.
[0011] Furthermore, the diameter of the MIG main welding wire is 1.2~1.6mm, and the diameter of the cold wire is 1.0~1.2mm.
[0012] Furthermore, the inert gas mixture is composed of a mixture of argon and helium.
[0013] Furthermore, in step S4, the low-power pulsed laser parameters are as follows: the laser type is a pulsed laser, the actual working average power adjustment range is 200~500W, the pulse frequency is 50~200Hz, the pulse width is 1~5ms, and the laser incident angle is 45°~60°.
[0014] Furthermore, in step S4, the MIG welding parameters are as follows: welding current is 80~120A, welding voltage is 18~22V; main wire feed speed is 5.0~7.0m / min, arc length correction value is -20%~-30%, and wire extension is 12~16mm; bypass cold wire feed speed is 2.5~4.5m / min; and the ratio of cold wire feed speed to main wire feed speed is controlled to be 0.4~0.7.
[0015] Furthermore, in step S4, during multilayer additive manufacturing, the overlap rate between single-pass layers is controlled at 40%~60%, and the interlayer temperature is controlled at 80~120℃.
[0016] Compared with the prior art, the present invention has the following advantages: 1. This invention innovatively employs a pulsed laser-MIG composite heat source and a co-source bypass cold wire synergistic filling technology, achieving the synergistic linkage of low-power pulsed laser, MIG arc, and cold wire. This effectively solves the core technical challenges of incomplete forming, poor molten pool stability, and high defect rate encountered when manufacturing magnesium alloys using single laser, single MIG, and conventional composite additive processes. The low-power pulsed laser can gently preheat the substrate, refine the grains, and help stabilize the molten pool, avoiding the problems of concentrated heat input, accelerated oxidation, and component deformation caused by high-power lasers, thus reducing magnesium alloy oxidation and molten pool disturbance. The MIG arc enables efficient wire feeding and melting, and the cold wire relies on the residual heat of the molten pool formed by the synergy of both to achieve rapid fusion and filling without the need for an additional heat source. This increases the single-pass layer filling amount while avoiding component deformation and hot cracking defects caused by additional heat input. Simultaneously, the co-source magnesium alloy filling ensures a good metallurgical bond between the main welding wire, cold wire, and substrate, significantly reducing interface defects and effectively improving the density and mechanical properties of the additive components. Metallographic examination and mechanical property testing show that the magnesium alloy components prepared by this invention have a density of over 99.5%, a tensile strength of ≥240MPa, and an elongation of ≥11%. Compared with single MIG additive components, the density is increased by 10%~15%, the tensile strength by 20%~25%, and the elongation by 25%~35%, and the performance is close to that of wrought magnesium alloys, which can meet the requirements of high-end applications.
[0017] 2. This invention optimizes the shielding gas ratio strategy by synergistically controlling pulsed laser parameters, MIG welding parameters, main welding wire feed speed, cold wire feed speed, and welding speed, thus constructing a precise process parameter matching system for the entire process. This effectively reduces oxidation loss and defects such as porosity, inclusions, and hot cracks during the magnesium alloy additive manufacturing process. The mixed shielding gas of argon and helium ensures good inert protection, especially suppressing the oxidation of magnesium alloys under low-power pulsed laser irradiation, while also improving the fluidity of the molten pool and enhancing the laser's penetration ability. The interpass temperature is controlled by a temperature sensor and cooling... The coordinated control of module, laser parameters, and MIG parameters precisely maintains the temperature between 80 and 120°C, effectively avoiding grain coarsening and residual internal stress accumulation. At the same time, the highly efficient synergistic characteristics of the low-power pulsed laser and the MIG composite heat source, combined with cold wire filling, significantly improve the forming efficiency and energy utilization rate, achieving a forming accuracy of ±0.08mm, meeting the manufacturing requirements of high-precision magnesium alloy complex components. The optimized design of the laser and MIG welding torch positions further expands the coverage of the shielding gas, reducing the number of internal pores in the component to 1 / 10 to 1 / 12 of that in single MIG additive manufacturing.
[0018] 3. This invention, without requiring major modifications to existing pulsed laser and MIG equipment, achieves separate control of composite heat source energy and material deposition by adding a bypass cold wire feeding system. This significantly increases the forming thickness and width of a single layer, greatly improving additive manufacturing efficiency. Compared to single MIG additive manufacturing technology, forming efficiency is increased by 50%~70%, and compared to single low-power pulsed laser additive manufacturing technology, forming efficiency is increased by 180%~220%. At the same time, through precise control of process parameters, welding wire loss during the additive manufacturing process is reduced, and the welding wire utilization rate can reach over 96%, effectively reducing manufacturing costs. The optimized design of the wire feeding speed ratio between the main welding wire and the cold wire further balances forming efficiency and forming quality, effectively avoiding defects such as cold wire incomplete fusion, incomplete penetration, or over-melting. The coordinated adjustment of low-power pulsed laser and MIG parameters achieves efficient energy utilization, with energy utilization rate 30%~40% higher than conventional laser-MIG composite additive manufacturing.
[0019] 4. The present invention has a reasonable structural design, is easy to operate, and has strong stability. The coordinated linkage of each system realizes precise control of the entire additive forming process. Through the rotatable and adjustable bracket, the position and angle of the laser focusing head, MIG welding gun and bypass wire feed nozzle can be flexibly adjusted to meet the additive forming needs of magnesium alloy components of different shapes and sizes. 5. This invention is applicable to the efficient and high-precision additive manufacturing of complex high-performance magnesium alloy components in fields such as aerospace, automotive lightweighting, and high-end electronic equipment. It effectively solves the problems of high forming difficulty, high mold cost, cumbersome process, and low material utilization in the traditional manufacturing of magnesium alloy components. At the same time, it overcomes the inherent defects of existing single and conventional composite additive manufacturing processes. Compared with high-power laser equipment, the cost of pulsed laser is reduced by 40% to 60%, which further reduces the manufacturing cost and significantly expands the application range of magnesium alloy materials. It has important engineering application value and broad prospects for industrialization. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the process for a magnesium alloy laser-MIG bypass cold filament filled composite additive manufacturing method proposed in this invention. Figure 2 This is a schematic diagram illustrating the forming effect of an embodiment of the present invention.
[0021] In the attached figures, the following reference numerals are used: 1-substrate; 2-deposited layer; 3-main welding wire; 4-welding gun; 5-laser gun head; 6-cold wire; 7-working platform Detailed Implementation To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0022] See appendix Figure 1 The present invention proposes a laser-MIG bypass cold wire filling composite additive manufacturing method for magnesium alloys. It adopts a laser-MIG composite heat source and delivers a non-energized cold wire 6 for filling through a bypass independent wire feeding mechanism. The cold wire 6 is fed synchronously with the main welding wire 3, thereby achieving decoupled control of arc energy and deposition rate. The method aims to solve the technical problems existing in the current single MIG or laser additive manufacturing of magnesium alloys, such as poor molten pool stability, incomplete forming, high defect rate, difficulty in precise control of heat input, insufficient mechanical properties, low energy utilization, and difficulty in balancing forming efficiency and precision.
[0023] The additive manufacturing apparatus includes a low-power pulsed laser-MIG composite welding system, a bypass cold wire feeding system, a protective gas system, a motion control system, and a forming platform. These systems work together to achieve precise additive forming.
[0024] The method specifically includes the following steps: S1. A magnesium alloy plate is selected as the substrate 1, which is similar in composition to the MIG main welding wire 3 and the bypass cold wire 6. The surface of the substrate 1 is polished, degreased with anhydrous ethanol, and dried to remove impurities to meet the process requirements.
[0025] S2. Build a low-power pulsed laser-MIG bypass cold wire filler composite additive manufacturing system: Load the magnesium alloy MIG main welding wire 3 into the wire feeding mechanism of the MIG welding torch 4, load the magnesium alloy cold wire 6 into the bypass wire feeding mechanism, adjust the relative positions of the low-power pulsed laser generator, the MIG welding torch 4 and the bypass wire feeding nozzle to ensure that the low-power pulsed laser, the MIG arc and the cold wire conveying trajectory are precisely matched, and the cold wire can be accurately fed into the edge of the molten pool; The MIG main welding wire 3 and the bypass cold wire 6 are made of the same magnesium alloy with identical chemical composition and mass fraction. The material is selected from AZ31 or AZ80 series, with Al content of 2.5%~4.0%, Zn content of 0.5%~1.0%, Mn content of 0.2%~0.5%, and the remainder being Mg matrix and unavoidable trace impurities, with a total impurity mass fraction ≤0.15%. The homogeneous magnesium alloy filling design ensures a good metallurgical bond without interface defects between the main welding wire 3, the cold wire 6 and the substrate 1, avoiding defects such as brittle phases and microcracks caused by dissimilar metal filling. At the same time, the specific content of Mn element can form a high-density Mn-Fe intermetallic compound with the Fe element in the magnesium alloy matrix, achieving effective purification of the matrix structure and significant refinement of solidified grains, greatly improving the mechanical properties and service stability of additive components.
[0026] The diameter of the MIG main welding wire 3 is 1.2~1.6mm, and the diameter of the cold wire 6 is 1.0~1.2mm.
[0027] S3. Inert gas mixture of argon (Ar) and helium (He) is introduced into the additive forming area, and the flow rate of the protective gas is controlled.
[0028] S4. Layered Additive Manufacturing: Simultaneously start the low-power pulsed laser generator and MIG power supply, set and calibrate the pulsed laser parameters and MIG welding parameters; the low-power pulsed laser acts on the substrate surface to achieve gentle preheating, while assisting in the formation of a stable molten pool; the MIG arc melts the magnesium alloy main welding wire 3 to form a uniform molten pool; simultaneously start the bypass wire feeding mechanism to uniformly feed the magnesium alloy cold wire 6 into the edge of the molten pool; the cold wire 6 relies on the residual heat of the molten pool formed by the synergistic effect of the low-power pulsed laser and the MIG arc to achieve rapid and uniform fusion filling; among which... The parameters for precise control of low-power pulsed laser are as follows: a fiber pulsed laser generator is used, the laser type is pulsed laser, the maximum average power is 500W, the actual working average power control range is 200~500W, the pulse frequency is 50~200Hz, the pulse width is 1~5ms, and the laser incident angle is 45°~60°.
[0029] The precise control of MIG welding parameters is as follows: using pulsed MIG welding mode, the welding current is 80~120A, the welding voltage is 18~22V; the main welding wire 3 feed speed is 5.0~7.0m / min, the arc length correction value is -20%~-30%, and the welding torch extension is 12~16mm; the bypass cold wire 6 feed speed is 2.5~4.5m / min; the ratio of the cold wire 6 feed speed to the main welding wire 3 feed speed is controlled at 0.4~0.7 to ensure that the cold wire 6 is fully fused and does not affect the stability of the weld pool, thereby achieving synergistic energy complementarity between low-power pulsed laser and MIG arc, and thus ensuring the density and mechanical properties of the formed parts.
[0030] During multilayer additive manufacturing, the overlap rate between single-pass layers is controlled at 40%~60%, and the interlayer temperature is controlled at 80~120℃. When the temperature sensor detects that the interlayer temperature is higher than 120℃, the system automatically pauses the additive manufacturing operation and resumes operation after natural cooling or cooling down to the set temperature range through the cooling module of the work platform 7. This effectively avoids defects such as coarse grains, residual internal stress accumulation, and thermal cracks caused by excessively high interlayer temperatures.
[0031] When additively forming complex curved surface components, the 3D model of the target component is first imported through the CAD / CAM programming function of the motion control system. After layer slicing, an adaptive additive forming trajectory is generated. At the same time, a laser displacement sensor fixed to the end of the robotic arm monitors the welding torch nozzle height, laser focusing distance, and vertical distance between the substrate / formed layer surface in real time. Combined with the dynamic adjustment function of the six-axis industrial robotic arm, the welding torch height, laser focusing position, and additive travel speed are optimized in real time to ensure that the size and shape of the molten pool remain stable throughout the additive process. The thickness of a single additive layer is precisely controlled within 1.8~2.8mm, and the width of a single additive layer is precisely controlled within 4~6mm, which can significantly improve the forming accuracy and batch consistency of complex curved surface components.
[0032] S5. Post-processing: After additive forming is completed, the component is subjected to stress-relief annealing to eliminate residual internal stress generated during the additive process; then the surface of the component is polished and repaired to remove surface oxide scale, spatter and excess protrusions to ensure that the surface flatness and dimensional accuracy of the component meet the standards.
[0033] The method of the present invention will be further illustrated below through specific embodiments: A method for laser-MIG bypass cold-filament filled composite additive manufacturing of magnesium alloys includes the following steps: S1. Substrate Pretreatment: AZ31 magnesium alloy sheet was selected as the substrate, with dimensions of 400mm×400mm×10mm. The chemical composition of the substrate by mass fraction was: Al 3.12%, Zn 0.84%, Mn 0.2%, Fe 0.002%, Si 0.01%, with the remainder being Mg matrix and unavoidable trace impurities. The substrate surface was polished with 120-grit water-resistant sandpaper to thoroughly remove surface oxide scale and floating rust. Then, the substrate surface was wiped with anhydrous ethanol to remove oil stains and adsorbed impurities. Finally, the substrate was placed in a constant temperature drying oven at 90℃ for 20 minutes to ensure that the substrate surface was free of oxidation, oil stains, and adsorbed moisture.
[0034] S2. Equipment Debugging: Build a low-power pulsed laser-MIG bypass cold wire filler composite additive manufacturing system. Load the AZ31 magnesium alloy MIG main welding wire (1.2mm diameter) into the MIG welding torch wire feeding mechanism, and load the AZ31 magnesium alloy cold wire (1.0mm diameter) into the bypass wire feeding mechanism. Precisely adjust the relative positions of the laser focusing head, MIG welding torch, and bypass wire feeding nozzle so that the laser focusing point is 3mm in front of the MIG welding torch arc, the laser focusing spot diameter is 1.0mm, and the laser incident angle is 50°. Adjust the angle between the MIG welding torch and the substrate to 70°, the distance between the bypass wire feeding nozzle and the MIG welding torch nozzle to 10mm, and the angle between the wire feeding direction and the welding torch travel direction to 35°. Complete the equipment debugging and calibration. The maximum average power of the low-power pulsed laser generator is 500W.
[0035] S3. Protective gas setting: Introduce a mixed protective gas of argon and helium into the additive forming area, with argon comprising 75% and helium comprising 25%. Adjust the protective gas flow rate to 22L / min to ensure that the molten pool, heat-affected zone, and low-power pulsed laser irradiation area are completely covered by the protective gas atmosphere.
[0036] S4. Layered Additive Manufacturing: Simultaneously start the low-power pulsed laser generator and MIG power supply, and set the laser parameters: laser type is pulsed laser, average power is 300W (maximum average power is 500W), pulse frequency is 100Hz, pulse width is 3ms, and both laser scanning speed and welding speed are 0.4m / min; set the MIG welding parameters: welding current is 100A, welding voltage is 20V, main wire feed speed is 6.0m / min, arc length correction value is -25%, and wire extension is 14mm. A low-power pulsed laser acts on the substrate surface to achieve gentle preheating, grain refinement, and assist in the formation of a stable molten pool. The MIG arc melts the magnesium alloy main welding wire to form a uniform molten pool. Simultaneously, the bypass wire feeding mechanism is activated to feed the magnesium alloy cold wire at a uniform speed of 3.5 m / min to the edge of the molten pool (the ratio of the cold wire to the main welding wire feeding speed is 0.58). The motion control system controls the robotic arm to drive the laser focusing head, MIG welding torch, and bypass wire feeding nozzle to move at a uniform speed along a preset trajectory to complete single-pass additive manufacturing. The above single-pass additive manufacturing process is repeated to achieve multi-layer cumulative additive manufacturing. The interlayer overlap rate is controlled at 50%. The interlayer temperature is monitored and controlled at 100℃ in real time by a temperature sensor. When the interlayer temperature is higher than 100℃, the system automatically reduces the laser power by 25%, the MIG welding current by 15A, and pauses the bypass wire feeding. After natural cooling to 100℃, all parameters and wire feeding operations are restored.
[0037] S5. Post-processing: After additive forming, the component undergoes stress-relieving annealing at 220℃ for 1.5 hours, followed by furnace cooling to room temperature. The surface is then polished with 120-grit sandpaper to remove oxide scale, welding spatter, and excess protrusions, yielding a magnesium alloy component of the target dimensions. The forming effect is as follows: Figure 2 As shown.
[0038] In this embodiment, the additive manufacturing apparatus includes a low-power pulsed laser-MIG hybrid welding system, a bypass cold wire feeding system, a shielding gas system, a motion control system, and a forming platform. The low-power pulsed laser-MIG hybrid welding system includes a fiber pulsed laser generator, a laser focusing head, a MIG power supply, a water-cooled MIG welding torch, and a servo main welding wire feeder (wire feeding accuracy ±0.1m / min). The bypass cold wire feeding system includes a servo bypass wire feeder, a high-purity alumina ceramic wire feed nozzle, and a gear-driven rotatable adjustable bracket. The wire feed nozzle outlet is equipped with a rigid... The guide sleeve is made of high-quality alloy, with a gap of 0.15mm between the guide sleeve and the cold wire. The adjustable bracket has an adjustment angle range of 0°~90° and an adjustment accuracy of ±1°. The protective gas system includes a protective gas cylinder, a high-pressure pressure reducing valve, a precision flow meter (accuracy ±0.5L / min), and an annular gas nozzle. The motion control system includes a CNC console, a six-axis industrial robotic arm (travel accuracy ±0.05mm), and a laser displacement sensor. The forming platform surface is equipped with a flexible positioning fixture, and the interior is equipped with a high-precision temperature sensor (accuracy ±2℃) and a cooling module.
[0039] The magnesium alloy component prepared in this embodiment, after testing, has the following characteristics: density of 99.7%, tensile strength of 255 MPa, elongation of 12.8%, forming accuracy of ±0.07 mm, and a smooth surface without obvious defects such as pores, inclusions, or hot cracks. The forming efficiency is about 60% higher than that of single MIG additive manufacturing and about 200% higher than that of single low-power pulsed laser additive manufacturing. The welding wire utilization rate reaches 96.5%, and the energy utilization rate is about 35% higher than that of conventional laser-MIG composite additive manufacturing, fully meeting the performance and precision requirements of complex magnesium alloy components in the aerospace field.
[0040] All matters not covered in this invention are common knowledge.
[0041] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. A method for laser-MIG bypass cold-filament filled composite additive manufacturing of magnesium alloys, characterized in that: The method includes the following steps: S1. Select magnesium alloy sheet as the base material, which is similar in composition to MIG main welding wire and bypass cold wire, and pre-treat the surface of the base material. S2. Build a low-power pulsed laser-MIG bypass cold wire filler composite additive manufacturing system: Load the magnesium alloy MIG main welding wire into the MIG welding torch wire feeding mechanism, load the magnesium alloy cold wire into the bypass wire feeding mechanism, adjust the relative positions of the low-power pulsed laser generator, MIG welding torch and bypass wire feeding nozzle to ensure that the low-power pulsed laser, MIG arc and cold wire delivery trajectory are precisely matched, and the cold wire can be accurately fed into the edge of the molten pool; S3. Inert mixed gas is introduced into the additive forming area, and the flow rate of the protective gas is controlled; S4. Layered Additive Manufacturing: Simultaneously start the low-power pulsed laser generator and MIG power supply, set and calibrate the pulsed laser parameters and MIG welding parameters; the low-power pulsed laser acts on the substrate surface to achieve gentle preheating, while assisting in the formation of a stable molten pool; the MIG arc melts the magnesium alloy main welding wire to form a uniform molten pool; simultaneously start the bypass wire feeding mechanism to feed the magnesium alloy cold wire into the edge of the molten pool at a uniform speed; the cold wire relies on the residual heat of the molten pool formed by the synergistic effect of the low-power pulsed laser and the MIG arc to achieve rapid and uniform fusion filling; S5. Post-processing: After additive forming is completed, the component is subjected to stress-relief annealing to eliminate residual internal stress generated during the additive process; then the surface of the component is trimmed to ensure that the surface flatness and dimensional accuracy of the component meet the standards.
2. The method for laser-MIG bypass cold-filament filled composite additive manufacturing of magnesium alloys according to claim 1, characterized in that: The MIG main welding wire and the bypass cold wire are made of the same magnesium alloy with completely identical chemical composition and mass fraction. The material is selected from AZ31 or AZ80 series, with Al content of 2.5%~4.0%, Zn content of 0.5%~1.0%, Mn content of 0.2%~0.5%, and the remainder being Mg matrix and unavoidable trace impurities.
3. The method for laser-MIG bypass cold-filament filled composite additive manufacturing of magnesium alloys according to claim 1 or 2, characterized in that: The diameter of the MIG main welding wire is 1.2~1.6mm, and the diameter of the cold wire is 1.0~1.2mm.
4. The method for laser-MIG bypass cold-filament filled composite additive manufacturing of magnesium alloys according to claim 1, characterized in that: The inert gas mixture is composed of argon and helium.
5. The method for laser-MIG bypass cold-filament filled composite additive manufacturing of magnesium alloys according to claim 1, characterized in that: In step S4, the low-power pulsed laser parameters are as follows: the laser type is a pulsed laser, the actual working average power adjustment range is 200~500W, the pulse frequency is 50~200Hz, the pulse width is 1~5ms, and the laser incident angle is 45°~60°.
6. The method for laser-MIG bypass cold-filament filled composite additive manufacturing of magnesium alloys according to claim 5, characterized in that: In step S4, the MIG welding parameters are as follows: welding current is 80~120A, welding voltage is 18~22V; main wire feed speed is 5.0~7.0m / min, arc length correction value is -20%~-30%, and wire extension is 12~16mm; bypass cold wire feed speed is 2.5~4.5m / min; and the ratio of cold wire feed speed to main wire feed speed is controlled at 0.4~0.
7.
7. The method for laser-MIG bypass cold-filament filled composite additive manufacturing of magnesium alloys according to claim 1, characterized in that: In step S4, during multilayer additive manufacturing, the overlap rate between single-pass layers is controlled at 40%~60%, and the interlayer temperature is controlled at 80~120℃.