Electric arc additive manufacturing method commonly used for ZM magnesium alloy

Abstract

The invention discloses an electric arc additive manufacturing method universal for ZM series magnesium alloys, which comprises the following steps of: 1, carrying out high-precision digital modeling, carrying out refined model subdivision according to geometrical characteristics of a workpiece, and carrying out targeted path planning according to a subdivision result; 2, preheating the magnesium alloy substrate, and introducing inert protective gas; 3, fixing the ZM-series magnesium alloy coiled wire in wire feeding equipment; fourthly, electric arc additive manufacturing parameters are input; 5, electric arc additive manufacturing; and sixthly, air cooling is conducted till the room temperature is reached, and the ZM-series magnesium alloy workpiece is obtained. The novel ZM magnesium alloy preparation method, namely the electric arc additive manufacturing method universal for the ZM magnesium alloy, is provided by considering the defects that the ZM magnesium alloy usually has many casting defects, low strength and the like, and according to the method, a magnesium alloy base plate is treated, and electric arc additive manufacturing parameters are controlled; the ZM-series magnesium alloy is prevented from common casting defects such as looseness and shrinkage cavities, the microstructure is fine and uniform, and the good mechanical property is achieved.

Description

Technical Field

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

[0002] As the lightest structural material at present, magnesium alloys have significant advantages such as low density, high specific strength and specific stiffness, excellent dimensional stability, good thermal and electrical conductivity, and outstanding casting and machining performance. However, with the increasing demand for complex magnesium alloy structural parts in various fields, the traditional manufacturing methods combining casting, forging and machining have exposed problems such as large machining allowance, low raw material utilization rate, and long preparation cycle, seriously affecting the R & D and production efficiency.

[0003] ZM series magnesium alloys (Mg-Zn-Zr) are widely used in the aerospace field for aircraft structural parts, missile casings and UAV frames due to their high strength, light weight and excellent processing performance. They are used in battery packs and wheels and other weight-reducing components in new energy vehicles, and also play an important role in fields such as laptop casings and heat dissipation components of electronic devices, and lightweight components of armored vehicles in military equipment. The existing research on ZM series magnesium alloys mainly includes casting, plastic forming, welding and heat treatment, but there are still obvious deficiencies: casting is prone to porosity and hot cracking, with poor formability and high work hardening rate; during welding, defects such as pores, oxidation and lack of fusion are likely to occur; the heat treatment process window is narrow and the performance improvement is limited; these factors restrict their application in high-end fields. Arc additive manufacturing (WAAM) has the advantages of high forming efficiency and low cost, and has become an important development direction for magnesium alloy additive manufacturing. In practical applications, in order to meet the design requirements of components with different sizes, a flexible path planning strategy needs to be adopted. In the traditional path strategy of arc additive manufacturing, during the welding process, overlapping multiple weld beads is usually used to achieve area filling. However, this strategy often leads to problems such as uneven surface or incomplete fusion between weld beads. However, cold metal transfer arc additive manufacturing (CMT-WAAM) shows unique potential in magnesium alloy processing.

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

[0005] The technical problem to be solved by the present invention is to provide an arc additive manufacturing method applicable to ZM series magnesium alloys in view of the deficiencies of the above-mentioned prior art. This method combines the material characteristics of ZM series magnesium alloys and ensures the stability of heat input during the printing process by controlling key factors such as welding speed, molten pool width and depth, and deposition layer lap continuity in the arc additive manufacturing process. It effectively reduces the spatter phenomenon during the printing process, reduces defects such as pores in the as-printed magnesium alloy, and thereby improves the strength of the as-printed ZM series magnesium alloy.

[0006] To solve the above technical problem, the technical solution adopted by the present invention is: an arc additive manufacturing method applicable to ZM series magnesium alloys, characterized in that this method uses an arc as a heat source and uses ZM series magnesium alloy wire as a raw material, and proceeds according to the following steps: Step 1: Use high-precision digital modeling software to perform high-precision digital modeling on the ZM series magnesium alloy workpiece, and perform refined model dissection based on the geometric characteristics of the ZM series magnesium alloy workpiece. Subsequently, perform partition path planning according to the refined model dissection results, and then optimize and design the printing paths of different regions in combination with the arc additive manufacturing process parameters. Finally, integrate and import the optimized printing path data and the refined model dissection results into the arc additive manufacturing equipment to obtain an arc additive manufacturing equipment with printing path data and model dissection results. Step 2: Perform mechanical polishing on the magnesium alloy substrate, and then fix it on the workbench of the arc additive manufacturing equipment with printing path data and model dissection 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 torch tip and the magnesium alloy substrate in the arc additive manufacturing equipment, and simultaneously introduce an inert protective gas. In addition, use a resistance heating sheet 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 wire in the wire feeding equipment, and adjust the wire outlet of the wire feeding equipment so that the ZM series magnesium alloy wire forms a certain angle with the preheated magnesium alloy substrate in the arc additive manufacturing equipment with a preheated magnesium alloy substrate obtained in Step 2 to obtain an arc additive manufacturing equipment and a wire feeding equipment ready for wire feeding. Step 4: Input the wire feeding speed, welding speed, oscillation, peak current, base current, arc voltage, lap rate, molten width and molten height of the molten pool into the arc additive manufacturing equipment and wire feeding equipment ready for wire feeding obtained in Step 3 to obtain an additive manufacturing equipment and a wire feeding equipment ready for arc additive manufacturing. Step 5: start the additive manufacturing equipment and wire feeding equipment to be manufactured by arc additive manufacturing obtained in step 4, so that the wire feeding equipment conveys the ZM series magnesium alloy coil wire to the welding area at a constant rate, melts it under the action of high-energy arc to form a molten pool, and prints one by one on the magnesium alloy substrate to form a single-layer entity according to the printing path data and the model segmentation result, and then realizes interlayer positioning by lifting the Z axis, and repeats the printing-cooling-lifting process until the precise forming of the full-size three-dimensional workpiece is completed 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.

[0007] The present invention performs high-precision digital modeling on a ZM series magnesium alloy workpiece and performs refined model segmentation according to geometric features, performs targeted path planning and design according to the segmentation results, and plans the printing paths of different parts of the cut layer according to the single-pass printing molten pool width range and overlap rate of arc additive manufacturing based on the printing path data and the refined model segmentation results and specific parameters of different parts of the ZM series magnesium alloy workpiece, such as wall thickness, shape, angle, etc., and controls the size of the molten pool by optimizing parameters, such as wire feeding speed, welding speed, swing, peak current, base current and arc voltage, to ensure that the width and height of the molten pool meet predetermined requirements, then determines a suitable overlap rate, and keeps the parameters except the above constant during the printing process, and realizes the printing process of arc additive manufacturing only by adjusting the wire feeding speed, peak current and base current, and finally leaves the formed workpieces stacked layer by layer in situ to be air-cooled until room temperature, so as to prevent deformation and cracking of the magnesium alloy workpiece caused by uneven or too fast heat dissipation, and completes the arc additive manufacturing of the ZM series magnesium alloy workpiece.

[0008] In the present invention, the magnesium alloy substrate is mechanically polished to remove the surface oxide film, an inert protective gas is introduced to ensure that the welding area is effectively isolated from the air to prevent oxidation and nitridation reactions, and the magnesium alloy substrate is preheated to further improve the molten pool fluidity and interlayer bonding quality.

[0009] The above arc additive manufacturing method generally applicable to ZM series magnesium alloys is characterized in that the thickness of the magnesium alloy substrate in step 2 is 40mm~60mm, and the magnesium alloy substrate is made of the same material as the ZM series magnesium alloy workpiece. The present invention limits the thickness of the magnesium alloy substrate to avoid the disadvantages of being too thin and easily deformed by heat, or too thick and difficult to heat and keep warm; and the length and width of the magnesium alloy substrate, that is, the area that supports the magnesium alloy workpiece, is determined by the size of the magnesium alloy workpiece.

[0010] The above-mentioned arc additive manufacturing method applicable to ZM series magnesium alloys is characterized in that the vertical distance between the welding torch tip and the magnesium alloy substrate in step two is 10 mm to 12 mm. The present invention maintains a stable arc length by controlling the vertical distance between the welding torch tip and the magnesium alloy substrate, thereby avoiding overheating or burn-through defects in the magnesium alloy.

[0011] The above-mentioned arc additive manufacturing method applicable to ZM series magnesium alloys is characterized in that the preheating temperature in step two is 150°C to 160°C. The present invention is conducive to controlling the continuity and stability of the molten pool by controlling the preheating temperature, thereby avoiding the phenomenon of porosity caused by lack of fusion during the printing process.

[0012] The above-mentioned arc additive manufacturing method applicable to ZM series magnesium alloys is characterized in that the diameter of the ZM series magnesium alloy wire coil in step three is 1.2 mm to 1.6 mm. The present invention controls the width of the molten pool by controlling the diameter of the ZM series magnesium alloy wire coil, thereby controlling the size of single-pass printing, and can also ensure that the wire material is completely melted during the printing process to reduce inclusions.

[0013] The above-mentioned arc additive manufacturing method applicable to ZM series magnesium alloys is characterized in that the included angle between the ZM series magnesium alloy wire coil and the upper surface of the magnesium alloy substrate in step three is 88° to 92°, the inert protective gas is argon, and the flow rate is 20 L / min to 25 L / min. The present invention ensures uniform printing or welding in the vertical direction by controlling the included angle between the ZM6 magnesium alloy wire coil and the magnesium alloy substrate, improves the bonding strength and reduces stress concentration; at the same time, controlling the flow rate of argon can not only effectively isolate oxygen to prevent oxidation of the magnesium alloy, but also stabilize the molten pool temperature and blow away impurities, thereby ensuring the stability of the processing process and the quality of the finished product.

[0014] The above-mentioned arc additive manufacturing method applicable to ZM series magnesium alloys is characterized in that in step four, the wire feeding speed is 9 m / min to 11 m / min, the welding speed is 6 mm / s to 10 mm / s, the oscillation is with a weld width of 3 mm to 40 mm, a step length of 2 mm to 36 mm, and a Z-shaped oscillation, the peak current is 145 A to 160 A, the base current is 120 A to 140 A, the arc voltage is 18 V to 22 V, the overlap ratio is 40% to 60%, the weld width of the molten pool is 10 mm to 12 mm, and the weld height is 2.0 mm to 3.0 mm. During the arc additive manufacturing process of the present invention, the magnitude of the current directly affects the macroscopic morphology and dimensions of the manufactured parts. When the current increases and the heat input increases, the fluidity of the molten metal in the molten pool increases. Under the stirring action of the arc, the layer width increases and the layer thickness decreases. At the same time, the temperature of the molten pool increases with the increase of the heat input, and the cooling rate decreases, and the grain size increases significantly. Similarly, when the wire feeding speed increases, it is equivalent to reducing the heat input obtained per unit length of the wire, the temperature of the molten pool decreases, and the cooling rate increases, thereby suppressing the flow of the molten metal in the molten pool, reducing the stirring effect of the arc on the molten pool, resulting in a decrease in the layer width of the molten pool and 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 adjusts two parameters, namely the current and the wire feeding speed, to ensure the printing quality before reaching the printing stable state, and at the same time considers factors such as the material physical properties of ZM series magnesium alloys, the heat input, the corresponding molten pool width, depth, and overlap continuity, and is applicable to the arc additive manufacturing of common ZM series magnesium alloys.

[0015] The above-mentioned arc additive manufacturing method applicable to ZM series magnesium alloys is characterized in that after forming a single-layer entity in step five, it is necessary to wait until the temperature of the single-layer entity drops to a temperature difference less than 5 °C from the magnesium alloy substrate before printing the next layer. By controlling the temperature, the present invention helps to ensure that the workpiece maintains a uniform organizational structure and performance during the forming process, thereby improving the quality and consistency of the workpiece.

[0016] The present invention has the following advantages compared with the prior art: 1. The present invention adopts the arc additive manufacturing method, based on the principle of cold metal transfer technology, combines the material physical properties of ZM series magnesium alloys, comprehensively considers factors such as the heat input, molten pool width, depth, and overlap continuity during the additive process of cold metal transfer technology, and proposes an arc additive manufacturing method applicable to ZM series magnesium alloys by regulating different process parameters. The ZM series magnesium alloys prepared by this method can avoid common casting defects such as porosity and shrinkage, and have fine and uniform microstructures and good mechanical properties.

[0017] 2. The present invention realizes the additive manufacturing of ZM series magnesium alloys by controlling the parameters of arc additive manufacturing, appropriately fine-tuning the parameters according to the actual situation, and adjusting the wire feeding speed and current magnitude.

[0018] 3. Compared with technologies such as gas metal arc 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 porosity, and effectively avoid problems such as unstable arc, molten pool overflow, and collapse during the cladding printing process.

[0019] 4. The arc additive manufacturing process of the present invention is simple, and the adjustment process of process parameters is easy to control. The obtained as-printed ZM series magnesium alloy workpieces have fine and uniform structures, good comprehensive mechanical properties, and are far superior to the as-cast state, solving the problems of uneven internal structure, anisotropy, and crack defects in the existing additive manufacturing of magnesium alloys.

[0020] 5. The method of the present invention is mainly applicable to the most commonly used ZM series magnesium alloys, and the process window range is clear, which is conducive to industrial production.

[0021] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. Brief Description of the Drawings

[0022] Figure 1 is a physical diagram of the magnesium alloy substrate in Embodiment 1 to Embodiment 3 of the present invention.

[0023] Figure 2 is a physical diagram of the ZM5 magnesium alloy workpiece prepared in Embodiment 1 of the present invention.

[0024] Figure 3 is the longitudinal section metallographic diagram of the ZM5 magnesium alloy workpiece prepared in Embodiment 1 of the present invention at the height position of 10 mm to 20 mm. Figure 4 is the longitudinal section metallographic diagram of the ZM5 magnesium alloy workpiece prepared in Embodiment 1 of the present invention at the height position of 30 mm to 40 mm.

[0025] Figure 5 is the longitudinal section metallographic diagram of the ZM5 magnesium alloy workpiece prepared in Embodiment 1 of the present invention at the height position of 80 mm to 90 mm.

[0026] Figure 6 is the mechanical property diagram of the ZM5 magnesium alloy workpiece prepared in Embodiment 1 of the present invention.

[0027] Figure 7 is a physical diagram of the ZM6 magnesium alloy workpiece prepared in Embodiment 2 of the present invention.

[0028] Figure 8 is the longitudinal section metallographic diagram of the ZM6 magnesium alloy workpiece prepared in Embodiment 2 of the present invention at the height position of 5 mm to 15 mm.

[0029] Figure 9 It is the longitudinal section metallographic diagram of the ZM6 magnesium alloy workpiece prepared in Example 2 of the present invention at the height position of 35 mm to 45 mm.

[0030] Figure 10 It is the longitudinal section metallographic diagram of the ZM6 magnesium alloy workpiece prepared in Example 2 of the present invention at the height position of 75 mm to 85 mm.

[0031] Figure 11 It is the mechanical property diagram of the ZM6 magnesium alloy workpiece prepared in Example 2 of the present invention.

[0032] Figure 12 It is the schematic diagram of the scanning path of the Z-shaped swing in Example 3 of the present invention.

[0033] Figure 13 It is the physical diagram of the ZM6 magnesium alloy workpiece prepared in Example 3 of the present invention.

[0034] Figure 14 It is the longitudinal section metallographic diagram of the ZM6 magnesium alloy workpiece prepared in Example 3 of the present invention at the height position of 25 mm to 35 mm.

[0035] Figure 15 It is the longitudinal section metallographic diagram of the ZM6 magnesium alloy workpiece prepared in Example 3 of the present invention at the height position of 80 mm to 90 mm.

[0036] Figure 16 It is the longitudinal section metallographic diagram of the ZM6 magnesium alloy workpiece prepared in Example 3 of the present invention at the height position of 140 mm to 150 mm. Detailed implementation manners

[0037] Figure 1 It is the physical diagram of the magnesium alloy substrate in Examples 1 to 3 of the present invention. It can be seen from Figure 1 that the magnesium alloy substrates in Examples 1 to 3 of the present invention are in the shape of circular plates.

[0038] Example 1 The arc additive manufacturing method in this example uses a welding torch with cold metal transfer technology to generate an arc as the heat source, and uses ZM5 magnesium alloy wire as the 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.

[0039] This example includes the following steps: Step 1: Use high-precision digital modeling software to perform high-precision digital modeling on a ZM5 magnesium alloy workpiece with dimensions of 120 mm × 20 mm × 90 mm, conduct refined model meshing based on the geometric features of the ZM5 magnesium alloy workpiece, then perform partition path planning according to the refined model meshing results, and then optimize and design the printing paths for different regions in combination with the arc additive manufacturing process parameters. Finally, integrate and import the optimized printing path data and the refined model meshing results into the arc additive manufacturing equipment to obtain the arc additive manufacturing equipment with printing path data and model meshing results. Step 2: Perform mechanical polishing on a magnesium alloy substrate with dimensions of 200 mm × 80 mm × 30 mm, then fix it on the workbench of the arc additive manufacturing equipment with printing path data and model meshing 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 torch tip and the magnesium alloy substrate in the arc additive manufacturing equipment to 12 mm, and simultaneously introduce argon gas with a flow rate of 25 L / min as the inert protective gas. In addition, use a resistance heating sheet to preheat the magnesium alloy substrate to 160 °C to obtain the arc additive manufacturing equipment with a preheated magnesium alloy substrate. Step 3: Fix a ZM5 magnesium alloy wire with a diameter of 1.6 mm in the wire feeding device, and adjust the wire outlet of the wire feeding device so that the angle between the ZM5 magnesium alloy wire and the upper surface of the preheated magnesium alloy substrate in the arc additive manufacturing equipment with a preheated magnesium alloy substrate obtained in Step 2 is 92 ° to obtain the arc additive manufacturing equipment and wire feeding device ready for wire feeding. Step 4: Input the wire feeding speed, welding speed, oscillation, peak current, base current, arc voltage, overlap ratio, weld width and weld height of the molten pool into the arc additive manufacturing equipment and wire feeding device ready for wire feeding obtained in Step 3 to obtain the additive manufacturing equipment and wire feeding device ready for arc additive manufacturing; the welding speed is 10 mm / s, the arc voltage is 22 V, the weld width of the molten pool is 12 mm, the weld height is 3.0 mm, the overlap ratio 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. Set the oscillation to a weld width of 40 mm, a step size of 36 mm, and a Z-shaped oscillation Step 5: Start the additive manufacturing equipment and wire feeding equipment to be used for arc additive manufacturing obtained in Step 4, and make the wire feeding equipment convey the ZM5 magnesium alloy wire coil to the welding area at a constant rate. The wire is melted to form a molten pool under the action of a high-energy arc. Then, according to the printing path data and the model dissection results, a single-layer entity is printed layer by layer on the magnesium alloy substrate. After forming a single-layer entity, it is necessary to wait until the temperature of the single-layer entity drops to a temperature difference less than 5 °C from the magnesium alloy substrate, and then perform the printing of the next layer. Then, layer-by-layer positioning is achieved by lifting along the Z-axis, and the printing-cooling-lifting process is repeated until the precise forming of a full-size three-dimensional workpiece is completed, obtaining a formed workpiece; Step 6: Let the formed workpiece obtained in Step 5 stand still in situ and air-cool until room temperature, obtaining a ZM5 magnesium alloy workpiece.

[0040] Figure 2 is a physical picture of the ZM5 magnesium alloy workpiece prepared in this embodiment. From Figure 2 it can be seen that the designed height of the ZM5 magnesium alloy workpiece prepared in this embodiment is 90 mm, and a total of 30 layers are printed, with an actual height reaching 96 mm. Figure 2 The numbers 1, 2, and 3 in Figure 3 represent the sampling positions in the vertical direction, and the sampled samples are named 1, 2, and 3.

[0041] Figure 3 is the longitudinal section metallographic picture of the ZM5 magnesium alloy workpiece prepared in this embodiment at the height position of 10 mm - 20 mm. Figure 4 is the longitudinal section metallographic picture of the ZM5 magnesium alloy workpiece prepared in this embodiment at the height position of 30 mm - 40 mm. Figure 5 is the longitudinal section metallographic picture of the ZM5 magnesium alloy workpiece prepared in this embodiment at the height position of 80 mm - 90 mm. From Figures 3 - 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.

[0042] For Figure 2 the samples sampled at positions 1, 2, 3, 4, 5, and 6 are subjected to mechanical property tests, and 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 in the horizontal and vertical directions are close. The average room-temperature tensile properties are: yield strength 122 MPa ± 8 MPa, tensile strength 253 MPa ± 12 MPa, and elongation 11% ± 1.8%.

[0043] Example 2 The arc additive manufacturing method of this embodiment uses a welding torch with cold metal transfer technology to generate an arc as the heat source, uses ZM6 magnesium alloy wire as the raw material, and 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.

[0044] This embodiment includes the following steps: Step 1: Use high-precision digital modeling software to perform high-precision digital modeling on a ZM6 magnesium alloy workpiece with a length × width × height of 80 mm × 30 mm × 90 mm, perform refined model segmentation based on the geometric characteristics of the ZM6 magnesium alloy workpiece, then perform partition path planning according to the refined model segmentation results, and then optimize and design the printing paths of different regions in combination with arc additive manufacturing process parameters. Finally, integrate and import the optimized printing path data and the refined model segmentation results into the arc additive manufacturing equipment to obtain an arc additive manufacturing equipment with printing path data and model segmentation results. Step 2: Perform mechanical polishing on a magnesium alloy substrate with a length × width × thickness of 400 mm × 400 mm × 50 mm, then fix it on the workbench of the arc additive manufacturing equipment with 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 torch tip and the magnesium alloy substrate in the arc additive manufacturing equipment to 11 mm, and simultaneously introduce argon with a flow rate of 23 L / min as an inert protective gas. In addition, use a resistance heating sheet to preheat the magnesium alloy substrate to 155 °C to obtain an arc additive manufacturing equipment with a preheated magnesium alloy substrate. Step 3: Fix a ZM6 magnesium alloy wire with a diameter of 1.4 mm in the wire feeding equipment, and adjust the wire outlet of the wire feeding equipment so that the angle between the ZM6 magnesium alloy wire and the upper surface of the preheated magnesium alloy substrate in the arc additive manufacturing equipment with a preheated magnesium alloy substrate obtained in Step 2 is 90° to obtain an arc additive manufacturing equipment and a wire feeding equipment to be wire-fed. Step 4: Input the wire feeding speed, welding speed, oscillation, peak current, base current, arc voltage, overlap ratio, weld width and weld height of the molten pool into the arc additive manufacturing equipment and wire feeding equipment to be wire-fed obtained in Step 3 to obtain an additive manufacturing equipment and a wire feeding equipment to be arc additively manufactured; the welding speed is 8 mm / s, the arc voltage is 20 V, the weld width of the molten pool is 11 mm, the weld height is 2.5 mm, the overlap ratio 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. Set the oscillation to a weld width of 20 mm, a step length of 18 mm, and a Z-shaped oscillation. Step 5: Start the additive manufacturing equipment and wire feeding equipment obtained in Step 4 for arc additive manufacturing, and make the wire feeding equipment convey the ZM6 magnesium alloy wire coil to the welding area at a constant rate. The wire is melted to form a molten pool under the action of a high-energy arc. Then, according to the printing path data and the model dissection result, a single-layer entity is printed layer by layer on the magnesium alloy substrate. After forming a single-layer entity, it is necessary to wait until the temperature of the single-layer entity drops to a temperature difference less than 5 °C from the magnesium alloy substrate, and then perform the printing of the next layer. Then, layer-by-layer positioning is achieved by lifting along the Z-axis, and the printing-cooling-lifting process is cycled until the precise forming of a full-size three-dimensional workpiece is completed, obtaining a formed workpiece. Step 6: In-situ static air-cool the formed workpiece obtained in Step 5 until it reaches room temperature, obtaining a ZM6 magnesium alloy workpiece.

[0045] Figure 7 is a physical picture of the ZM6 magnesium alloy workpiece prepared in this embodiment. From Figure 7 it can be seen that the designed height of the ZM6 magnesium alloy workpiece prepared in this embodiment is 90 mm, a total of 30 layers are printed, and the actual height reaches 92 mm. Figure 7 In Figure 7 1, 2, and 3 represent the sampling positions in the vertical direction, and the sampled samples are named 1, 2, and 3.

[0046] Figure 8 is the longitudinal section metallographic picture of the ZM6 magnesium alloy workpiece prepared in this embodiment at the height position of 5 mm to 15 mm. Figure 9 is the longitudinal section metallographic picture of the ZM6 magnesium alloy workpiece prepared in this embodiment at the height position of 35 mm to 45 mm. Figure 10 is the longitudinal section metallographic picture of the ZM6 magnesium alloy workpiece prepared in this embodiment at the height position of 75 mm to 85 mm. From Figures 8 - 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.

[0047] For Figure 7 the samples sampled at positions 1, 2, 3, 4, 5, and 6 in Figure 11 perform mechanical property tests, and the results are shown in Figure 11 From

[0048] Example 3 The wire arc additive manufacturing method of this embodiment uses a welding torch with cold metal transfer technology to generate an arc as the heat source, and uses ZM6 magnesium alloy wire as the 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.

[0049] This embodiment includes the following steps: Step 1: Use high-precision digital modeling software to perform high-precision digital modeling on a ZM6 magnesium alloy workpiece with a length × width × height of 200 mm × 80 mm × 160 mm, perform refined model dissection based on the geometric characteristics of the ZM6 magnesium alloy workpiece, then perform zoning path planning according to the refined model dissection results, and then optimize and design the printing paths of different regions in combination with the wire arc additive manufacturing process parameters. Finally, integrate and import the optimized printing path data and the refined model dissection results into the wire arc additive manufacturing equipment to obtain a wire arc additive manufacturing equipment with printing path data and model dissection results; Step 2: Perform mechanical polishing on a magnesium alloy substrate with a length × width × thickness of 400 mm × 400 mm × 50 mm, then fix it on the workbench of the wire arc additive manufacturing equipment with printing path data and model dissection results obtained in Step 1, and use the upper surface of the magnesium alloy substrate as the reference plane for wire arc additive manufacturing. Then adjust the vertical distance between the welding torch tip and the magnesium alloy substrate in the wire arc additive manufacturing equipment to 10 mm, and simultaneously introduce argon with a flow rate of 20 L / min as an inert protective gas. In addition, use a resistance heating sheet to preheat the magnesium alloy substrate to 150 °C to obtain a wire arc additive manufacturing equipment with a preheated magnesium alloy substrate; Step 3: Fix a ZM6 magnesium alloy wire with a diameter of 1.2 mm in the wire feeding equipment, and adjust the wire outlet of the wire feeding equipment so that the angle between the ZM series magnesium alloy wire and the upper surface of the preheated magnesium alloy substrate in the wire arc additive manufacturing equipment obtained in Step 2 is 88° to obtain a wire arc additive manufacturing equipment and a wire feeding equipment to be wire-fed; Step 4: Input the wire feeding speed, welding speed, oscillation, peak current, base current, arc voltage, overlap ratio, weld width and weld height of the molten pool into the wire arc additive manufacturing equipment and wire feeding equipment to be wire-fed obtained in Step 3 to obtain an additive manufacturing equipment and a wire feeding equipment to be wire arc additive manufactured; the welding speed is 6 mm / s, the arc voltage is 18 V, the weld width of the molten pool is 10 mm, the weld height is 2.0 mm, the overlap ratio 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. Set the oscillation to a weld width of 3 mm, a step length of 2 mm, and a Z-shaped oscillation; Step 5: Start the additive manufacturing equipment and wire feeding equipment to be arc additive manufactured 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 it under the action of a high-energy arc to form a molten pool, and according to the printing path data and the model dissection result, print layer by layer on the magnesium alloy substrate to form a single-layer entity. After forming a single-layer entity, it is necessary to wait until the temperature of the single-layer entity drops to a temperature difference less than 5 °C from the magnesium alloy substrate, and then perform the printing of the next layer. Then, realize the interlayer positioning by lifting along the Z-axis, and cycle the printing-cooling-lifting process until the precise forming of the full-size three-dimensional workpiece is completed to obtain the formed workpiece; Step 6: Let the formed workpiece obtained in Step 5 be statically air-cooled in situ until room temperature to obtain the ZM6 magnesium alloy workpiece.

[0050] Figure 12 is a schematic diagram of the scanning path of the Z-shaped swing in this embodiment. From Figure 12 it can be seen that 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-shaped swing.

[0051] Figure 13 is a physical picture of the ZM6 magnesium alloy workpiece prepared in this embodiment. From Figure 13 it can be seen that the designed height of the ZM6 magnesium alloy workpiece is 160 mm, a total of 55 layers are printed, and the actual height reaches 165 mm.

[0052] Figure 14 is the longitudinal section metallographic diagram of the ZM6 magnesium alloy workpiece prepared in this embodiment at the height position of 25 mm to 35 mm, Figure 15 is the longitudinal section metallographic diagram of the ZM6 magnesium alloy workpiece prepared in this embodiment at the height position of 80 mm to 90 mm, Figure 16 is the longitudinal section metallographic diagram of the ZM6 magnesium alloy workpiece prepared in this embodiment at the height position of 140 mm to 150 mm. From Figures 14 - 16 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 28 μm ± 5 μm.

[0053] After testing, the ZM6 magnesium alloy workpiece prepared in this embodiment has no common casting defects such as porosity and shrinkage cavity, and the microstructure is fine and uniform, and has good mechanical properties.

[0054] After testing, the diameter of the large-size indium crystal prepared in this embodiment is greater than 25 mm, and the height is greater than 400 mm.

[0055] The above is only a preferred embodiment of the present invention, and does not impose any limitation on the present invention. Any simple modification, change, and equivalent change made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. An arc additive manufacturing method applicable to ZM series magnesium alloys, characterized in that, This method uses an electric arc as the heat source and ZM series magnesium alloy wire as the raw material, and proceeds as follows: Step 1: Use high-precision digital modeling software to perform high-precision digital modeling on the ZM series magnesium alloy workpiece, and conduct refined model meshing based on the geometric features of the ZM series magnesium alloy workpiece. Subsequently, perform partition path planning according to the refined model meshing results, then optimize the printing paths of different regions in combination with the process parameters of arc additive manufacturing, and finally integrate and import the optimized printing path data and the refined model meshing results into the arc additive manufacturing equipment to obtain the arc additive manufacturing equipment with printing path data and model meshing results; Step 2: Mechanically polish the magnesium alloy substrate, and then fix it on the workbench of the arc additive manufacturing equipment with printing path data and model meshing 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 torch tip and the magnesium alloy substrate in the arc additive manufacturing equipment, and simultaneously introduce an inert protective gas. In addition, use a resistance heating sheet to preheat the magnesium alloy substrate to obtain the arc additive manufacturing equipment with a preheated magnesium alloy substrate; Step 3: Fix the ZM series magnesium alloy wire in the wire feeding equipment, and adjust the wire outlet of the wire feeding equipment so that the ZM series magnesium alloy wire forms a certain angle with the preheated magnesium alloy substrate in the arc additive manufacturing equipment obtained in Step 2 to obtain the arc additive manufacturing equipment and wire feeding equipment to be wire-fed; Step 4: Input the wire feeding speed, welding speed, oscillation, peak current, base current, arc voltage, lap rate, weld width and weld height of the molten pool into the arc additive manufacturing equipment and wire feeding equipment to be wire-fed obtained in Step 3 to obtain the additive manufacturing equipment and wire feeding equipment to be arc additively manufactured; Step 5: Start the additive manufacturing equipment and wire feeding equipment to be arc additively manufactured obtained in Step 4, so that the wire feeding equipment conveys the ZM series magnesium alloy wire to the welding area at a constant rate, melts under the action of a high-energy electric arc to form a molten pool, and according to the printing path data and model meshing results, print layer by layer on the magnesium alloy substrate to form a single-layer entity. Then, realize interlayer positioning by lifting along the Z axis, and cycle the printing-cooling-lifting process until the precise forming of a full-size three-dimensional workpiece is completed to obtain a formed workpiece; Step 6: Let the formed workpiece obtained in Step 5 stand still in situ and air-cool until room temperature to obtain the ZM series magnesium alloy workpiece.

2. The arc additive manufacturing method for ZM series magnesium alloys according to claim 1, wherein In Step 2, the thickness of the magnesium alloy substrate 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 wire arc additive manufacturing method for ZM series magnesium alloys according to claim 1, wherein In Step 2, the vertical distance between the welding torch tip and the magnesium alloy substrate in the arc additive manufacturing equipment is 10 mm to 12 mm.

4. A wire arc additive manufacturing method for ZM series magnesium alloys according to claim 1, characterized in that, In Step 2, the preheating temperature is 150 °C to 160 °C.

5. A wire arc additive manufacturing method applicable to ZM series magnesium alloys according to claim 1, characterized in that, In Step 3, the diameter of the ZM series magnesium alloy wire 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 wire and the upper surface of the magnesium alloy substrate is 88° to 92°, the inert protective gas is argon, and the flow rate introduced is 20 L / min to 25 L / min.

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

8. A wire arc additive manufacturing method applicable to ZM series 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 proceeding with the printing of the next layer.

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