An arc additive manufacturing method commonly used for ZM series magnesium alloys

Abstract

The present invention discloses an arc additive manufacturing method applicable to ZM-series magnesium alloys. The method comprises: 1. performing high-precision digital modeling and performing refined model segmentation based on the geometric features of the workpiece, and performing targeted path planning based on the segmentation results; 2. preheating the magnesium alloy substrate and introducing an inert shielding gas; 3. securing the ZM-series magnesium alloy coil wire in a wire feeding device; 4. inputting arc additive manufacturing parameters; 5. performing arc additive manufacturing; 6. air cooling to room temperature to obtain the ZM-series magnesium alloy workpiece. Considering the shortcomings of ZM-series magnesium alloys, such as numerous casting defects and low strength, the present invention proposes a new ZM-series magnesium alloy preparation method, namely, an arc additive manufacturing method applicable to ZM-series magnesium alloys. By treating the magnesium alloy substrate and controlling the arc additive manufacturing parameters, the ZM-series magnesium alloy avoids common casting defects such as porosity and shrinkage, and has a fine and uniform microstructure and good mechanical properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal additive manufacturing, and in particular relates to an arc additive manufacturing method generally applicable to ZM series magnesium alloys. Background Art

[0002] As the lightest structural material currently available, magnesium alloys offer significant advantages, including low density, high specific strength and stiffness, excellent dimensional stability, good thermal and electrical conductivity, and exceptional casting and machinability. However, with the increasing demand for complex magnesium alloy structural parts across various fields, traditional manufacturing methods combining casting, forging, and machining have exposed problems such as large machining allowances, low raw material utilization, and long lead times, seriously impacting R&D and production efficiency.

[0003] ZM magnesium alloys (Mg-Zn-Zr) are widely used in the aerospace industry for aircraft structural components, missile casings, and drone frames due to their high strength, lightweight construction, and excellent processability. They are also used in weight-reducing components such as battery packs and wheels in new energy vehicles. They also play an important role in applications such as laptop housings and heat sinks for electronic devices, and lightweight components for armored vehicles in military equipment. Existing research on ZM magnesium alloys primarily encompasses casting, plastic forming, welding, and heat treatment, but significant limitations remain. Casting is prone to shrinkage and hot cracking, resulting in poor formability and high work hardening rates. Welding is prone to defects such as porosity, oxidation, and lack of fusion. Furthermore, the heat treatment process window is narrow, limiting performance improvements. These factors restrict their application in high-end applications. Wire arc additive manufacturing (WAAM), with its advantages of high forming efficiency and low cost, has become a key development direction in magnesium alloy additive manufacturing. In practical applications, flexible path planning strategies are required to meet the design requirements of varying component sizes. Conventional wire arc additive manufacturing path planning strategies typically employ overlapping weld passes to achieve area filling during welding. However, this strategy often leads to some problems, such as uneven surface or incomplete fusion between weld beads, but cold metal transfer arc additive manufacturing (CMT-WAAM) has shown unique potential in magnesium alloy processing.

[0004] Therefore, there is an urgent need for an arc additive manufacturing method that is universally applicable to ZM series magnesium alloys, which is crucial for improving the performance of additively manufactured ZM series magnesium alloys. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the shortcomings of the above-mentioned existing technologies and provide an arc additive manufacturing method applicable to ZM-series magnesium alloys. This method, taking into account the material characteristics of ZM-series magnesium alloys, controls key factors such as welding speed, molten pool width and depth, and deposited layer overlap continuity during the arc additive manufacturing process. This ensures stable heat input during the printing process, effectively reduces spattering during printing, and reduces defects such as porosity in the printed magnesium alloy, thereby improving the strength of the printed ZM-series magnesium alloy.

[0006] To solve the above technical problems, the present invention adopts a technical solution: an arc additive manufacturing method generally applicable to ZM series magnesium alloys, characterized in that the method uses an arc as a heat source and a ZM series magnesium alloy coiled wire as a raw material, and is carried out according to the following steps:

[0007] Step 1: Use high-precision digital modeling software to perform high-precision digital modeling of the ZM series magnesium alloy workpiece, and perform refined model segmentation based on the geometric characteristics of the ZM series magnesium alloy workpiece. Then, perform partition path planning based on the refined model segmentation results. Then, combine the arc additive manufacturing process parameters to optimize the design of printing paths in different areas. Finally, integrate the optimized printing path data and the refined model segmentation results and import them into the arc additive manufacturing equipment to obtain the arc additive manufacturing equipment with the printing path data and model segmentation results.

[0008] Step 2: Mechanically polish the magnesium alloy substrate, and then fix it on the workbench of the arc additive manufacturing equipment with the printing path data and model segmentation results obtained in Step 1, and use the upper surface of the magnesium alloy substrate as the reference plane for arc additive manufacturing. Then, adjust the vertical distance between the welding gun head and the magnesium alloy substrate in the arc additive manufacturing equipment, and introduce inert shielding gas at the same time. In addition, use a resistance heating plate to preheat the magnesium alloy substrate to obtain an arc additive manufacturing equipment with a preheated magnesium alloy substrate;

[0009] Step 3: Fix the ZM series magnesium alloy coiled wire in the wire feeding device, and adjust the wire outlet of the wire feeding device so that the ZM series magnesium alloy coiled wire maintains a certain angle with the preheated magnesium alloy substrate in the arc additive manufacturing device with the preheated magnesium alloy substrate obtained in step 2, thereby obtaining the arc additive manufacturing device and the wire feeding device to be fed with wire;

[0010] Step 4: Inputting wire feeding speed, welding speed, oscillation, peak current, base current, arc voltage, overlap rate, molten pool width and molten pool height into the arc additive manufacturing equipment and wire feeding equipment to be fed with wire obtained in step 3, thereby obtaining the additive manufacturing equipment and wire feeding equipment to be fed with wire;

[0011] Step 5: Start the additive manufacturing equipment and wire feeding equipment for arc additive manufacturing obtained in step 4, and make the wire feeding equipment deliver the ZM series magnesium alloy wire to the welding area at a constant rate, melt it under the action of the high-energy arc to form a molten pool, and print one layer at a time on the magnesium alloy substrate according to the printing path data and the model segmentation result, and then achieve interlayer positioning by lifting the Z axis, and repeat the printing-cooling-lifting process until the full-size three-dimensional workpiece is accurately formed to obtain a formed workpiece;

[0012] Step 6: The formed workpiece obtained in step 5 is left to stand in situ and air-cooled until it reaches room temperature to obtain a ZM series magnesium alloy workpiece.

[0013] The present invention performs high-precision digital modeling of a ZM-series magnesium alloy workpiece and performs refined model segmentation based on geometric features. Targeted path planning and design are performed based on the segmentation results. Based on the printing path data and the refined model segmentation results, as well as specific parameters of different parts of the ZM-series magnesium alloy workpiece, such as wall thickness, shape, and angle, the printing paths for different parts of the layer are planned for the width range and overlap rate of a single-pass printing melt pool in combination with arc additive manufacturing. The size of the melt pool is controlled by optimizing parameters such as wire feed speed, welding speed, oscillation, peak current, base current, and arc voltage to ensure that the width and height of the melt pool meet predetermined requirements. Next, a suitable overlap rate is determined, and all other parameters except those listed above are kept constant during the printing process. The arc additive manufacturing printing process is achieved by adjusting only the wire feed speed, peak current, and base current. Finally, the layered workpiece is air-cooled in situ to room temperature to prevent deformation and cracking of the magnesium alloy workpiece due to uneven or excessive heat dissipation, thereby completing the arc additive manufacturing of the ZM-series magnesium alloy workpiece.

[0014] In the present invention, the magnesium alloy substrate is mechanically polished to remove the surface oxide film, and an inert protective gas is introduced to ensure that the welding area is effectively isolated from the air to prevent oxidation and nitriding reactions. The magnesium alloy substrate is preheated to further improve the molten pool fluidity and interlayer bonding quality.

[0015] The aforementioned arc additive manufacturing method, applicable to ZM-series magnesium alloys, is characterized in that the magnesium alloy substrate in step 2 has a thickness of 40 mm to 60 mm and is made of the same material as the ZM-series magnesium alloy workpiece. By limiting the thickness of the magnesium alloy substrate, the present invention avoids the drawbacks of being too thin, where it is susceptible to thermal deformation, or too thick, where it is difficult to heat and maintain. The length and width of the magnesium alloy substrate, which supports the magnesium alloy workpiece, are determined by the size of the magnesium alloy workpiece.

[0016] The aforementioned arc additive manufacturing method, applicable to ZM-series magnesium alloys, is characterized in that the vertical distance between the welding gun tip and the magnesium alloy substrate in the arc additive manufacturing equipment in step 2 is 10 mm to 12 mm. By controlling the vertical distance between the welding gun tip and the magnesium alloy substrate, the present invention maintains a stable arc length, thereby preventing overheating and burn-through defects in the magnesium alloy.

[0017] The aforementioned arc additive manufacturing method, which is generally applicable to ZM magnesium alloys, is characterized in that the preheating temperature in step 2 is 150°C to 160°C. Controlling the preheating temperature facilitates controlling the continuity and stability of the molten pool, thereby avoiding the occurrence of incomplete fusion and the generation of pores during the printing process.

[0018] The aforementioned arc additive manufacturing method, which is generally applicable to ZM magnesium alloys, is characterized in that the diameter of the ZM magnesium alloy coiled wire in step 3 is 1.2 mm to 1.6 mm. By controlling the diameter of the ZM magnesium alloy coiled wire, the present invention facilitates controlling the width of the molten pool, thereby controlling the size of a single print pass, while also ensuring complete melting of the wire during the printing process to reduce inclusions.

[0019] The aforementioned arc additive manufacturing method, which is generally applicable to ZM-series magnesium alloys, is characterized in that the angle between the ZM-series magnesium alloy coil and the upper surface of the magnesium alloy substrate in step three is 88° to 92°, and the inert shielding gas is argon at a flow rate of 20L / min to 25L / min. By controlling the angle between the ZM6 magnesium alloy coil and the magnesium alloy substrate, the present invention ensures uniform vertical printing or welding, improves bond strength, and reduces stress concentration. Simultaneously, controlling the argon flow rate effectively isolates oxygen to prevent oxidation of the magnesium alloy, stabilizes the molten pool temperature, and removes impurities, thereby ensuring process stability and finished product quality.

[0020] The above-mentioned arc additive manufacturing method, which is generally applicable to ZM magnesium alloys, is characterized in that the wire feeding speed in step 4 is 9m / min~11m / min, the welding speed is 6mm / s~10mm / s, the oscillation is a weld width of 3mm~40mm, a step length of 2mm~36mm, and a Z-shaped oscillation, the peak current is 145A~160A, the base current is 120A~140A, the arc voltage is 18V~22V, the overlap rate is 40%~60%, the molten pool width is 10mm~12mm, and the molten pool height is 2.0mm~3.0mm. In the arc additive manufacturing process of the present invention, the magnitude of the current directly affects the macroscopic morphology and size of the manufactured parts. Increasing the current and the heat input increases the fluidity of the molten metal in the molten pool. Under the stirring action of the arc, the layer width increases and the layer thickness decreases; at the same time, the molten pool temperature increases with the increase of heat input, and the cooling rate decreases, and the grain size increases significantly. Similarly, an increase in the wire feeding speed is equivalent to reducing the heat input obtained per unit length of wire, reducing the molten pool temperature and accelerating the cooling rate, thereby inhibiting the flow of molten metal in the molten pool and reducing the stirring effect of the arc on the molten pool, resulting in a decrease in the molten pool layer width, an increase in the layer thickness, and a decrease in the grain size. Therefore, the present invention controls the process and parameters of arc additive manufacturing printing, and usually ensures the printing quality by adjusting the two parameters of current and wire feeding speed before reaching a stable printing state. At the same time, it takes into account the material properties characteristics, heat input, corresponding molten pool width, depth, overlap continuity and other factors of ZM series magnesium alloys, and is suitable for arc additive manufacturing of common ZM series magnesium alloys.

[0021] The aforementioned arc additive manufacturing method, applicable to ZM magnesium alloys, is characterized by the fact that after forming a single layer in step 5, the temperature of the single layer must be allowed to drop to a temperature difference of less than 5°C from the magnesium alloy substrate before printing the next layer. This temperature control helps ensure that the workpiece maintains a uniform structure and properties during the forming process, thereby improving workpiece quality and consistency.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. The present invention adopts an arc additive manufacturing method, based on the principle of cold metal transfer technology, combined with the material properties of ZM series magnesium alloys, and comprehensively considers factors such as heat input, molten pool width, depth, and overlap continuity in the cold metal transfer technology additive process. By regulating different process parameters, an arc additive manufacturing method that is generally applicable to ZM series magnesium alloys is proposed. The ZM series magnesium alloy prepared by this method can avoid common casting defects such as looseness and shrinkage, and has a fine and uniform microstructure and good mechanical properties.

[0024] 2. The present invention controls the parameters of arc additive manufacturing, fine-tunes the parameters appropriately according to actual conditions, and adjusts the wire feeding speed and current to achieve additive preparation of ZM series magnesium alloys.

[0025] 3. Compared with technologies such as metal inert gas shielded welding, the heat input during the printing process of the present invention is more stable, which can reduce the generation of defects such as spatter and pores, and effectively avoid problems such as arc instability, molten pool overflow and collapse during the cladding printing process.

[0026] 4. The arc additive manufacturing process of the present invention is simple, and the process parameter adjustment process is easy to control. The printed ZM magnesium alloy workpiece obtained has a fine and uniform structure, good comprehensive mechanical properties, and is far superior to the cast state, solving the problems of uneven internal structure, anisotropy and crack defects of existing additively manufactured magnesium alloys.

[0027] 5. The method of the present invention is mainly applicable to the most commonly used ZM series magnesium alloys, has a clear process window range, and is conducive to industrial production.

[0028] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a physical picture of the magnesium alloy substrate in Examples 1 to 3 of the present invention.

[0030] Figure 2 This is a physical picture of the ZM5 magnesium alloy workpiece prepared in Example 1 of the present invention.

[0031] Figure 3 This is a metallographic image of a longitudinal section of a ZM5 magnesium alloy workpiece at a height of 10 mm to 20 mm prepared in Example 1 of the present invention.

[0032] Figure 4 This is a metallographic image of a longitudinal section of a ZM5 magnesium alloy workpiece prepared in Example 1 of the present invention at a height of 30 mm to 40 mm.

[0033] Figure 5 This is a metallographic image of a longitudinal section of a ZM5 magnesium alloy workpiece prepared in Example 1 of the present invention at a height of 80 mm to 90 mm.

[0034] Figure 6 This is a diagram of the mechanical properties of the ZM5 magnesium alloy workpiece prepared in Example 1 of the present invention.

[0035] Figure 7 This is a physical picture of the ZM6 magnesium alloy workpiece prepared in Example 2 of the present invention.

[0036] Figure 8This is a metallographic image of a longitudinal section of a ZM6 magnesium alloy workpiece prepared in Example 2 of the present invention at a height of 5 mm to 15 mm.

[0037] Figure 9 This is a metallographic image of a longitudinal section of a ZM6 magnesium alloy workpiece prepared in Example 2 of the present invention at a height of 35 mm to 45 mm.

[0038] Figure 10 This is a metallographic image of a longitudinal section of a ZM6 magnesium alloy workpiece prepared in Example 2 of the present invention at a height of 75 mm to 85 mm.

[0039] Figure 11 This is a diagram of the mechanical properties of the ZM6 magnesium alloy workpiece prepared in Example 2 of the present invention.

[0040] Figure 12 Schematic diagram of the scanning path of the Z-shaped oscillation in Example 3 of the present invention.

[0041] Figure 13 This is a physical picture of the ZM6 magnesium alloy workpiece prepared in Example 3 of the present invention.

[0042] Figure 14 This is a metallographic image of a longitudinal section of a ZM6 magnesium alloy workpiece prepared in Example 3 of the present invention at a height of 25 mm to 35 mm.

[0043] Figure 15 This is a metallographic image of a longitudinal section of a ZM6 magnesium alloy workpiece prepared in Example 3 of the present invention at a height of 80 mm to 90 mm.

[0044] Figure 16 This is a metallographic image of a longitudinal section of a ZM6 magnesium alloy workpiece prepared in Example 3 of the present invention at a height of 140 mm to 150 mm. DETAILED DESCRIPTION

[0045] Figure 1 This is a physical picture of the magnesium alloy substrate in Examples 1 to 3 of the present invention. Figure 1 It can be seen from the figure that the magnesium alloy substrates in Examples 1 to 3 of the present invention are in the shape of a circular plate.

[0046] Example 1

[0047] The arc additive manufacturing method of this embodiment uses a welding gun using a cold metal transfer technology to generate an arc as a heat source, and uses ZM5 magnesium alloy wire as a raw material. The mass fraction of Al in the ZM5 magnesium alloy wire is 8.70%, the mass fraction of Zn is 0.52%, the mass fraction of Zn is 0.52%, the mass fraction of Mn is 0.26%, and the rest is Mg.

[0048] This embodiment includes the following steps:

[0049] Step 1: Use high-precision digital modeling software to perform high-precision digital modeling of a ZM5 magnesium alloy workpiece with a length, width, and height of 120 mm, 20 mm, and 90 mm. A refined model segmentation is then performed based on the geometric features of the ZM5 magnesium alloy workpiece. Subsequently, partition path planning is performed based on the refined model segmentation results. The printing paths of different areas are then optimized and designed in combination with the arc additive manufacturing process parameters. Finally, the optimized printing path data and the refined model segmentation results are integrated and imported into the arc additive manufacturing equipment to obtain the arc additive manufacturing equipment with the printing path data and model segmentation results.

[0050] Step 2: Mechanically polish a magnesium alloy substrate with a length × width × thickness of 200 mm × 80 mm × 30 mm, and then fix it on the workbench of the arc additive manufacturing equipment with the printing path data and model segmentation results obtained in step 1, and use the upper surface of the magnesium alloy substrate as the reference plane for arc additive manufacturing. Then, adjust the vertical distance between the welding gun head and the magnesium alloy substrate in the arc additive manufacturing equipment to 12 mm, and introduce argon gas at a flow rate of 25 L / min as an inert shielding gas. In addition, use a resistance heating plate to preheat the magnesium alloy substrate to 160° C. to obtain an arc additive manufacturing equipment with a preheated magnesium alloy substrate;

[0051] Step 3: Fix a ZM5 magnesium alloy coiled wire with a diameter of 1.6 mm in a wire feeding device, and adjust the wire outlet of the wire feeding device so that the angle between the ZM5 magnesium alloy coiled wire and the upper surface of the preheated magnesium alloy substrate in the arc additive manufacturing device with a preheated magnesium alloy substrate obtained in step 2 is 92°, thereby obtaining the arc additive manufacturing device and wire feeding device to be fed with wire;

[0052] Step 4: Input the wire feeding speed, welding speed, swing, peak current, base current, arc voltage, overlap rate, molten pool width and molten height into the arc additive manufacturing equipment and wire feeding equipment to be fed with wire obtained in step 3 to obtain the additive manufacturing equipment and wire feeding equipment to be fed with arc additive manufacturing; the welding speed is 10 mm / s, the arc voltage is 22 V, the molten pool width is 12 mm, the molten height is 3.0 mm, the overlap rate is 60%, and the deposition stability is maintained by fine-tuning the peak current to 160 A, the base current to 140 A and the wire feeding speed to 11 m / min, and the swing is set to a weld width of 40 mm, a step length of 36 mm, and a Z-type swing.

[0053] Step 5: Start the additive manufacturing equipment and wire feeding equipment for arc additive manufacturing obtained in step 4, so that the wire feeding equipment conveys the ZM5 magnesium alloy wire coil to the welding area at a constant rate, melts under the action of the high-energy arc to form a molten pool, and prints one layer at a time on the magnesium alloy substrate according to the printing path data and the model segmentation result to form a single-layer entity. After the single-layer entity is formed, it is necessary to wait for the temperature of the single-layer entity to drop to a temperature difference of less than 5°C with the magnesium alloy substrate before printing the next layer. Then, interlayer positioning is achieved by lifting the Z-axis, and the printing-cooling-lifting process is repeated until the full-size three-dimensional workpiece is accurately formed to obtain a formed workpiece.

[0054] Step 6: The formed workpiece obtained in step 5 is left to stand in situ and air-cooled until it reaches room temperature to obtain a ZM5 magnesium alloy workpiece.

[0055] Figure 2 This is a physical picture of the ZM5 magnesium alloy workpiece prepared in this embodiment. Figure 2 It can be seen that the design height of the ZM5 magnesium alloy workpiece prepared in this embodiment is 90 mm, and a total of 30 layers are printed, and the actual height reaches 96 mm. Figure 2 The 1, 2, and 3 in the figure represent the locations where samples are taken in the vertical direction, and the samples are named 1, 2, and 3. Figure 3 The 4, 5, and 6 in the figure indicate the positions where sampling is performed in the horizontal direction, and the samples taken are named 4, 5, and 6.

[0056] Figure 3 This is a metallographic image of a longitudinal section of a ZM5 magnesium alloy workpiece prepared in this embodiment at a height of 10 mm to 20 mm. Figure 4 This is a metallographic image of a longitudinal section of a ZM5 magnesium alloy workpiece at a height of 30 mm to 40 mm prepared in this embodiment. Figure 5 This is a metallographic image of a longitudinal section of a ZM5 magnesium alloy workpiece at a height of 80 mm to 90 mm prepared in this embodiment. Figures 3 to 5 It can be seen that the ZM5 magnesium alloy workpiece prepared in this embodiment is evenly distributed from bottom to top, and the average grain size is 32 μm±2 μm.

[0057] right Figure 2 The mechanical properties of the samples taken at positions 1, 2, 3, 4, 5, and 6 were tested. The results are shown in Figure 6 ,from Figure 6 It can be seen that the room temperature tensile properties of the ZM5 magnesium alloy workpiece prepared in this embodiment are similar in horizontal and vertical directions, and the average room temperature tensile properties are: yield strength 122 MPa±8 MPa, tensile strength 253 MPa±12 MPa, and elongation 11%±1.8%.

[0058] Example 2

[0059] The arc additive manufacturing method of this embodiment uses a welding gun using cold metal transfer technology to generate an arc as a heat source, and uses ZM6 magnesium alloy wire as a raw material. The mass fraction of Nd in the ZM6 magnesium alloy wire is 2.71%, the mass fraction of Ni is 0.0005%, the mass fraction of Zn is 0.56%, the mass fraction of Zr is 0.44%, and the balance is Mg.

[0060] This embodiment includes the following steps:

[0061] Step 1: Use high-precision digital modeling software to perform high-precision digital modeling of a ZM6 magnesium alloy workpiece with a length, width, and height of 80 mm, 30 mm, and 90 mm. A refined model segmentation is then performed based on the geometric features of the ZM6 magnesium alloy workpiece. Subsequently, partition path planning is performed based on the refined model segmentation results. The printing paths of different areas are then optimized and designed in combination with the arc additive manufacturing process parameters. Finally, the optimized printing path data and the refined model segmentation results are integrated and imported into the arc additive manufacturing equipment to obtain the arc additive manufacturing equipment with the printing path data and model segmentation results.

[0062] Step 2: Mechanically polish a magnesium alloy substrate having dimensions of 400 mm in length, width, and thickness (400 mm, 400 mm, and 50 mm), and then fix it on a workbench of an arc additive manufacturing device having the printing path data and model segmentation results obtained in step 1. The upper surface of the magnesium alloy substrate is used as a reference plane for arc additive manufacturing. The vertical distance between the welding gun tip and the magnesium alloy substrate in the arc additive manufacturing device is adjusted to 11 mm, and argon gas is introduced at a flow rate of 23 L / min as an inert shielding gas. In addition, a resistance heating plate is used to preheat the magnesium alloy substrate to 155° C., thereby obtaining an arc additive manufacturing device having a preheated magnesium alloy substrate.

[0063] Step 3: Fix a ZM6 magnesium alloy coiled wire with a diameter of 1.4 mm in a wire feeding device, and adjust the wire outlet of the wire feeding device so that the angle between the ZM6 magnesium alloy coiled wire and the upper surface of the preheated magnesium alloy substrate in the arc additive manufacturing device with a preheated magnesium alloy substrate obtained in step 2 is 90°, thereby obtaining the arc additive manufacturing device and wire feeding device to be fed with wire;

[0064] Step 4. Input the wire feeding speed, welding speed, swing, peak current, base current, arc voltage, overlap rate, molten pool width and molten height into the arc additive manufacturing device and wire feeding device to be fed with wire obtained in step 3 to obtain the additive manufacturing device and wire feeding device to be subjected to arc additive manufacturing; the welding speed is 8 mm / s, the arc voltage is 20 V, the molten pool width is 11 mm, the molten height is 2.5 mm, the overlap rate is 50%, and the printing stability is maintained by fine-tuning the peak current to 150 A, the base current to 130 A, and the wire feeding speed to 10 m / min, and the swing is set to a weld width of 20 mm, a step length of 18 mm, and a Z-shaped swing;

[0065] Step 5: Start the additive manufacturing equipment and wire feeding equipment for arc additive manufacturing obtained in step 4, so that the wire feeding equipment conveys the ZM6 magnesium alloy wire coil to the welding area at a constant rate, melts under the action of the high-energy arc to form a molten pool, and prints one layer at a time on the magnesium alloy substrate according to the printing path data and the model segmentation results to form a single-layer entity. After the single-layer entity is formed, it is necessary to wait for the temperature of the single-layer entity to drop to a temperature difference of less than 5°C with the magnesium alloy substrate before printing the next layer. Then, interlayer positioning is achieved by lifting the Z-axis, and the printing-cooling-lifting process is repeated until the full-size three-dimensional workpiece is accurately formed to obtain a formed workpiece.

[0066] Step 6: The formed workpiece obtained in step 5 is left to stand in situ and air-cooled until it reaches room temperature to obtain a ZM6 magnesium alloy workpiece.

[0067] Figure 7 This is a physical picture of the ZM6 magnesium alloy workpiece prepared in this embodiment. Figure 7 It can be seen that the design height of the ZM6 magnesium alloy workpiece prepared in this embodiment is 90 mm, and a total of 30 layers are printed, and the actual height reaches 92 mm. Figure 7 The 1, 2, and 3 in the figure represent the locations where samples are taken in the vertical direction, and the samples are named 1, 2, and 3. Figure 7 The 4, 5, and 6 in the figure indicate the positions where sampling is performed in the horizontal direction, and the samples taken are named 4, 5, and 6.

[0068] Figure 8 This is a metallographic image of a longitudinal section of a ZM6 magnesium alloy workpiece prepared in this embodiment at a height of 5 mm to 15 mm. Figure 9 This is a metallographic image of a longitudinal section of a ZM6 magnesium alloy workpiece at a height of 35 mm to 45 mm prepared in this embodiment. Figure 10 This is a metallographic image of a longitudinal section of a ZM6 magnesium alloy workpiece at a height of 75 mm to 85 mm prepared in this embodiment. Figures 8 to 10 It can be seen that the ZM6 magnesium alloy workpiece prepared in this embodiment is evenly distributed from bottom to top, and the average grain size is 27 μm±4 μm.

[0069] right Figure 7 The mechanical properties of the samples taken at positions 1, 2, 3, 4, 5, and 6 were tested. The results are shown in Figure 11 ,from Figure 11 It can be seen that the room temperature tensile properties of the ZM6 magnesium alloy workpiece prepared in this embodiment are similar in horizontal and vertical directions, and the average room temperature tensile properties are: yield strength 169 MPa±8 MPa, tensile strength 300 MPa±6 MPa, and elongation 13%±1.8%.

[0070] Example 3

[0071] The arc additive manufacturing method of this embodiment uses a welding gun using cold metal transfer technology to generate an arc as a heat source, and uses ZM6 magnesium alloy wire as a raw material. The mass fraction of Nd in the ZM6 magnesium alloy wire is 2.71%, the mass fraction of Ni is 0.0005%, the mass fraction of Zn is 0.56%, the mass fraction of Zr is 0.44%, and the balance is Mg.

[0072] This embodiment includes the following steps:

[0073] Step 1: Use high-precision digital modeling software to perform high-precision digital modeling of a ZM6 magnesium alloy workpiece with dimensions of 200 mm (length, width, and height) by 80 mm (length, width, and height) by 160 mm. A refined model segmentation is then performed based on the geometric features of the ZM6 magnesium alloy workpiece. Subsequently, partition path planning is performed based on the refined model segmentation results. The printing paths of different areas are then optimized and designed in combination with the arc additive manufacturing process parameters. Finally, the optimized printing path data and the refined model segmentation results are integrated and imported into the arc additive manufacturing equipment to obtain the arc additive manufacturing equipment with the printing path data and model segmentation results.

[0074] Step 2: Mechanically polish a magnesium alloy substrate having a length × width × thickness of 400 mm × 400 mm × 50 mm, and then fix it on the workbench of the arc additive manufacturing equipment having the printing path data and the model segmentation result obtained in step 1, and use the upper surface of the magnesium alloy substrate as the reference plane for arc additive manufacturing. Then, adjust the vertical distance between the welding gun head and the magnesium alloy substrate in the arc additive manufacturing equipment to 10 mm, and introduce argon gas at a flow rate of 20 L / min as an inert shielding gas. In addition, use a resistance heating plate to preheat the magnesium alloy substrate to 150° C. to obtain an arc additive manufacturing equipment with a preheated magnesium alloy substrate.

[0075] Step 3: Fix a ZM6 magnesium alloy coiled wire with a diameter of 1.2 mm in a wire feeding device, and adjust the wire outlet of the wire feeding device so that the angle between the ZM series magnesium alloy coiled wire and the upper surface of the preheated magnesium alloy substrate in the arc additive manufacturing device with a preheated magnesium alloy substrate obtained in step 2 is 88°, thereby obtaining the arc additive manufacturing device and wire feeding device to be fed with wire;

[0076] Step 4. Input the wire feeding speed, welding speed, swing, peak current, base current, arc voltage, overlap rate, molten pool width and molten height into the arc additive manufacturing equipment and wire feeding equipment to be fed with wire obtained in step 3 to obtain the additive manufacturing equipment and wire feeding equipment to be subjected to arc additive manufacturing; the welding speed is 6 mm / s, the arc voltage is 18 V, the molten pool width is 10 mm, the molten height is 2.0 mm, the overlap rate is 40%, and the printing stability is maintained by fine-tuning the peak current to 145 A, the base current to 120 A, and the wire feeding speed to 10.5 m / min, and the swing is set to a weld width of 3 mm, a step length of 2 mm, and a Z-shaped swing;

[0077] Step 5: Start the additive manufacturing equipment and wire feeding equipment for arc additive manufacturing obtained in step 4, so that the wire feeding equipment conveys the ZM6 magnesium alloy wire coil to the welding area at a constant rate, melts under the action of the high-energy arc to form a molten pool, and prints one layer at a time on the magnesium alloy substrate according to the printing path data and the model segmentation results to form a single-layer entity. After the single-layer entity is formed, it is necessary to wait for the temperature of the single-layer entity to drop to a temperature difference of less than 5°C with the magnesium alloy substrate before printing the next layer. Then, interlayer positioning is achieved by lifting the Z-axis, and the printing-cooling-lifting process is repeated until the full-size three-dimensional workpiece is accurately formed to obtain a formed workpiece.

[0078] Step 6: The formed workpiece obtained in step 5 is left to stand in situ and air-cooled until it reaches room temperature to obtain a ZM6 magnesium alloy workpiece.

[0079] Figure 12 is a schematic diagram of the scanning path of the Z-shaped swing in this embodiment, Figure 12 As can be seen from the figure, the hollow arrow and the solid line on the hollow arrow represent the scanning path, and the small arrow represents the swing path of the Z-type swing.

[0080] Figure 13 This is a physical picture of the ZM6 magnesium alloy workpiece prepared in this embodiment. Figure 13 It can be seen that the design height of the ZM6 magnesium alloy workpiece is 160mm, a total of 55 layers are printed, and the actual height reaches 165mm.

[0081] Figure 14 : is a metallographic image of a longitudinal section of a ZM6 magnesium alloy workpiece prepared in this embodiment at a height of 25 mm to 35 mm. Figure 15 This is a metallographic image of a longitudinal section of a ZM6 magnesium alloy workpiece prepared in this embodiment at a height of 80 mm to 90 mm. Figure 16 This is a metallographic image of a longitudinal section of a ZM6 magnesium alloy workpiece at a height of 140 mm to 150 mm prepared in this embodiment. Figures 14 to 16It can be seen from the figure that the ZM6 magnesium alloy workpiece prepared in this embodiment is evenly distributed from bottom to top, and the average grain size is 28 μm±5 μm.

[0082] After testing, it was found that the ZM6 magnesium alloy workpiece prepared in this embodiment had no common casting defects such as porosity and shrinkage, and had a fine and uniform microstructure and good mechanical properties.

[0083] After testing, it was found that the large-sized indium crystals prepared in this embodiment had a diameter greater than 25 mm and a height greater than 400 mm.

[0084] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. An arc additive manufacturing method generally applicable to ZM series magnesium alloys, characterized in that: This method uses an arc as a heat source and ZM series magnesium alloy coiled wire as a raw material, and is carried out in the following steps: Step 1: Use high-precision digital modeling software to perform high-precision digital modeling of the ZM series magnesium alloy workpiece, and perform refined model segmentation based on the geometric characteristics of the ZM series magnesium alloy workpiece. Then, perform partition path planning based on the refined model segmentation results. Then, combine the arc additive manufacturing process parameters to optimize the design of printing paths in different areas. Finally, integrate the optimized printing path data and the refined model segmentation results and import them into the arc additive manufacturing equipment to obtain the arc additive manufacturing equipment with the printing path data and model segmentation results. Step 2: Mechanically polish the magnesium alloy substrate, and then fix it on the workbench of the arc additive manufacturing equipment with the printing path data and model segmentation results obtained in Step 1, and use the upper surface of the magnesium alloy substrate as the reference plane for arc additive manufacturing. Then, adjust the vertical distance between the welding gun head and the magnesium alloy substrate in the arc additive manufacturing equipment, and introduce inert shielding gas at the same time. In addition, use a resistance heating plate to preheat the magnesium alloy substrate to obtain an arc additive manufacturing equipment with a preheated magnesium alloy substrate; Step 3: Fix the ZM series magnesium alloy coiled wire in the wire feeding device, and adjust the wire outlet of the wire feeding device so that the ZM series magnesium alloy coiled wire maintains a certain angle with the preheated magnesium alloy substrate in the arc additive manufacturing device with the preheated magnesium alloy substrate obtained in step 2, thereby obtaining the arc additive manufacturing device and the wire feeding device to be fed with wire; Step 4: Inputting wire feeding speed, welding speed, oscillation, peak current, base current, arc voltage, overlap rate, molten pool width and molten pool height into the arc additive manufacturing equipment and wire feeding equipment to be fed with wire obtained in step 3, thereby obtaining the additive manufacturing equipment and wire feeding equipment to be fed with wire; Step 5: Start the additive manufacturing equipment and wire feeding equipment for arc additive manufacturing obtained in step 4, and make the wire feeding equipment deliver the ZM series magnesium alloy wire to the welding area at a constant rate, melt it under the action of the high-energy arc to form a molten pool, and print one layer at a time on the magnesium alloy substrate according to the printing path data and the model segmentation result, and then achieve interlayer positioning by lifting the Z axis, and repeat the printing-cooling-lifting process until the full-size three-dimensional workpiece is accurately formed to obtain a formed workpiece; Step 6: The formed workpiece obtained in step 5 is left to stand in situ and air-cooled until it reaches room temperature to obtain a ZM series magnesium alloy workpiece.

2. The arc additive manufacturing method for ZM magnesium alloys according to claim 1, characterized in that: The thickness of the magnesium alloy substrate in step 2 is 40 mm to 60 mm, and the material of the magnesium alloy substrate is the same as that of the ZM series magnesium alloy workpiece.

3. The arc additive manufacturing method for ZM series magnesium alloys according to claim 1, characterized in that: The vertical distance between the welding gun tip and the magnesium alloy substrate in the arc additive manufacturing equipment in step 2 is 10 mm to 12 mm.

4. The arc additive manufacturing method for ZM series magnesium alloys according to claim 1, characterized in that: The preheating temperature in step 2 is 150°C to 160°C.

5. The arc additive manufacturing method for ZM series magnesium alloys according to claim 1, characterized in that: The diameter of the ZM series magnesium alloy coiled wire in step 3 is 1.2 mm to 1.6 mm.

6. The arc additive manufacturing method for ZM series magnesium alloys according to claim 1, characterized in that: In step 3, the angle between the ZM series magnesium alloy coil wire and the upper surface of the magnesium alloy substrate is 88° to 92°, and the inert protective gas is argon, and the flow rate of the inert gas is 20 L / min to 25 L / min.

7. The arc additive manufacturing method for ZM series magnesium alloys according to claim 1, characterized in that: The wire feeding speed described in step 4 is 9m / min~11m / min, the welding speed is 6mm / s~10mm / s, the swing is 3mm~40mm in weld width, 2mm~36mm in step length, and Z-shaped swing. The peak current is 145A~160A, the base current is 120A~140A, the arc voltage is 18V~22V, the overlap rate is 40%~60%, the weld width of the molten pool is 10mm~12mm, and the weld height is 2.0mm~3.0mm.

8. The arc additive manufacturing method for ZM magnesium alloys according to claim 1, characterized in that: After forming a single-layer entity in step 5, it is necessary to wait until the temperature of the single-layer entity drops to a temperature difference of less than 5° C. from the magnesium alloy substrate before printing the next layer.

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