Aluminum steel composite structure friction stir additive manufacturing method

Abstract

The invention discloses a friction stir additive manufacturing method for an aluminum steel composite structure, relates to the field of heterogeneous material connection, aims to solve the problems of large interface stress and low joint strength in aluminum steel composite structure manufacturing, and comprises the following steps: carrying out mechanical polishing and cleaning on the surface of a steel plate before additive manufacturing; preparing a mechanical interlocking structure on the to-be-compounded surface; electrically driven silicon-magnesium co-permeation is carried out on the surface of the steel plate with the mechanical interlocking structure; a stirring friction additive manufacturing method is adopted, and multi-channel and multi-layer aluminum alloy deposition is carried out to reach the needed height; and the aluminum-steel composite structure transition joint is obtained through machining subtractive manufacturing. According to the method, through interface mechanical interlocking and silicon-magnesium co-penetration metallurgical connection, interface residual stress caused by difference of thermal expansion coefficients of the aluminum steel is relieved, excessive diffusion between the aluminum steel is inhibited, and interface brittleness caused by formation of excessive intermetallic compounds is avoided. The method not only can be applied to manufacturing of the aluminum-steel composite structure, but also can be popularized and applied to reliable manufacturing of an aluminum-titanium composite structure, a magnesium-steel composite structure and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of heterogeneous material connection, and particularly relates to a friction stir additive manufacturing method for an aluminum-steel composite structure. Background Art

[0002] As a typical representative of dissimilar metal composite materials, the aluminum-steel composite structure is showing unprecedented strategic value in the contemporary industrial manufacturing field. With the acceleration of the global energy structure transformation and the high-end equipment lightweight process, the application demand for aluminum-steel transition joints in key parts such as the pressurized conveying pipeline of aerospace aircraft, the anode steel claws of electrolytic aluminum smelting equipment, and the battery trays of new energy vehicles has shown an explosive growth. By organically combining the low density and high specific strength characteristics of aluminum alloy with the high rigidity and fatigue resistance of steel, such composite structures can not only achieve a significant effect of reducing the structure weight by 30%-50%, but also break through the performance bottleneck of single materials in extreme service environments. Taking the anode steel claws of electrolytic aluminum smelting equipment as an example, they need to withstand high-temperature environments of 250-350°C and ultra-high current loads at the same time. Using an aluminum-steel transition structure can effectively ensure the structural strength and energy consumption savings.

[0003] The traditional manufacturing technology of aluminum-steel composite structures has long been restricted by the technical bottlenecks brought about by the differences in physical metallurgical characteristics. The lattice constants of aluminum and iron differ by up to 28%, and brittle intermetallic compounds such as Fe4Al 13 and Fe2Al5 are easily formed in the molten state. Such hard and brittle phases are inevitable in the conventional fusion welding process, resulting in a sharp drop in the elongation of the joint to less than 5%. Even when using solid-state connection processes such as brazing and diffusion welding, technical problems such as insufficient interfacial bonding strength and narrow process windows still exist. More notably, most of the existing technologies are limited to the two-dimensional connection of simple-shaped parts and cannot meet the requirements of the integral manufacturing of three-dimensional complex components in modern engineering equipment. In the manufacturing of components with multi-chamber structures such as the drive motor housing of new energy vehicles, the traditional process requires separately processing the aluminum heat dissipation housing and the steel load-bearing frame and then performing secondary connection. This separation of processes not only reduces the material utilization rate by more than 40%, but also introduces residual stress in the subsequent assembly process, seriously affecting the fatigue life of the product.

[0004] Friction stir additive manufacturing technology has opened up a new path for the breakthrough development of aluminum-steel composite structures. Through the friction of the rotating stirring head with the large plastic deformation of metal materials, material deposition is achieved in the plastic flow state below the material melting point. This solid-phase deposition characteristic can effectively avoid the element segregation defects in the fusion welding process. More importantly, the severe plastic deformation generated by friction stir can form a unique mechanical interlock structure at the interface of dissimilar materials, and reconstruct the material microstructure through the dynamic recrystallization process. The previous tests of our team have shown that under optimized process parameters, a nano-transition layer with a width of 5-8 μm can be formed at the aluminum / steel interface, and the change in its microhardness gradient is reduced by more than 60% compared with the traditional process. Although this mechanical interlock mechanism significantly improves the interface bonding strength, it is still difficult to meet the long-term service requirements under extreme load conditions relying solely on physical embedding. When the composite structure bears alternating impact loads, microcracks may still initiate at the interface due to the lack of metallurgical bonding, and this problem is particularly prominent in dynamic load conditions such as spacecraft propulsion systems.

[0005] Therefore, introducing the silicon-magnesium co-permeation metallurgical connection mechanism is expected to be the key breakthrough to break through the existing technical bottlenecks. This binary co-permeation mechanism constructs a gradient-transition metallurgical bonding layer at the aluminum-steel interface, which is expected to relieve the interface stress. At the same time, combined with the mechanical interlock structure design of the aluminum-steel interface, a significant improvement in the strength of the aluminum-steel composite structure can be achieved. Under this background, developing friction stir additive manufacturing technology based on interface mechanical interlock and silicon-magnesium co-permeation metallurgical connection can not only break through the technical barriers of high-performance connection of dissimilar materials, but also promote the full-chain innovation of materials and manufacturing processes in fields such as aerospace vehicle pressurized transfer pipelines, anode steel claws for electrolytic aluminum smelting equipment, and new energy vehicle battery trays in China. Summary of the Invention

[0006] The present invention aims to solve the problems of large interface stress and low joint strength in the manufacture of aluminum-steel composite structures, and further proposes a friction stir additive manufacturing method for aluminum-steel composite structures.

[0007] The technical solutions adopted by the present invention to solve the above problems are as follows:

[0008] A friction stir additive manufacturing method for an aluminum-steel composite structure according to the present invention includes the following steps:

[0009] Step 1: Mechanically polish and clean the surface 101 of the steel plate 1 to be composite before additive manufacturing.

[0010] Step 2: Prepare a mechanical interlock structure 10101 on the surface 101 to be composite, specifically including:

[0011] Place the steel plate 1 in a space protected by an inert gas atmosphere, and use mechanical knurling or laser etching to fabricate a mechanical interlocking structure 10101 on the surface 101 of the steel plate. By adjusting parameters such as knurling depth / number of times or laser power / focus offset / scanning path, control the morphology of the mechanical interlocking structure 10101;

[0012] Step 3: Perform electro-driven silicon-magnesium co-permeation on the surface of the steel plate with a mechanical interlocking structure, specifically including:

[0013] Place the steel plate 1 with a mechanical interlocking structure in a eutectic molten salt mixture of 42% KCl - 58% MgCl2 (by mass fraction) protected by an inert gas atmosphere, and add nano-silica powder, auxiliary flux, reducing agent, etc. to the molten salt mixture. Use a carbon rod as the anode and the steel plate 1 as the cathode for pulsed electro-driven assisted infiltration to achieve co-permeation 10102 of silicon and magnesium on the surface of the steel plate;

[0014] Step 4: Use friction stir additive manufacturing method to deposit multi-pass and multi-layer aluminum alloy to the required height, specifically including:

[0015] Use friction stir additive manufacturing method to deposit multi-pass and multi-layer aluminum alloy 2 on the surface 101 of the steel plate until an aluminum-steel composite structure with the required height is obtained. By adjusting parameters such as feeding rate, layer height, overlap between passes, rotation speed, traveling speed, etc., control the forming quality of the deposited aluminum alloy 2;

[0016] Step 5: Use machining subtractive manufacturing to obtain the required aluminum-steel composite structure transition joint.

[0017] Further, in the step 1, the specific steps of grinding the surface 101 of the steel plate before additive manufacturing are: use an angle grinder to mechanically grind the surface 101 of the steel plate until the surface shows metallic luster and has no rust spots.

[0018] Further, in the step 1, the specific steps of cleaning the surface 101 of the steel plate before additive manufacturing are: wipe the surface 101 of the steel plate with anhydrous ethanol to remove oil stains, then perform alkali cleaning in a 10% NaOH solution at 80 - 90 °C for 10 minutes, and then transfer it to room temperature for pickling in a 5% HF + 5% HCl solution for 2 minutes. After rinsing with water, perform drying.

[0019] Further, in the step 2, the morphologies formed by mechanical knurling or laser etching include but are not limited to morphologies such as unidirectional wire grooves, multi-directional wire grooves, dot matrices, etc. The structural characteristic dimensions should be between 2 - 5 mm, and the depth is usually 0.2 - 1.5 mm. The hardness of the mechanical knurling tool used should be significantly greater than that of the steel plate 1 used to manufacture the aluminum-steel composite structure.

[0020] Further, in the step 3, the addition amount of nano-silica powder should be 5-20% (by mass fraction) of the eutectic molten salt mixture. The auxiliary flux used can be optionally but not limited to MgF2, KF, etc., and the addition amount is 0.5-3.0% (by mass fraction). The reducing agent used can be selected from at least one of magnesium powder and silicon powder, and the addition amount is 1.0-5.0% (by mass fraction).

[0021] Further, in the step 3, the process parameters of pulse electric drive-assisted diffusion infiltration are: working temperature 500-550 °C, current density 50-200 mA / cm 2 , pulse frequency 50 Hz, duty cycle 0.2-0.8, diffusion infiltration time 1-5 hours.

[0022] Further, in the step 4, the tools used for friction stir additive manufacturing include a stirring head, a follower sleeve, and additive raw materials. Among them: the stirring head is provided with a screw structure 301, with a rotation speed of 100-1200 rpm, and travels along the additive manufacturing path at a speed of 200-2000 mm / min to achieve multi-pass and multi-layer deposition; the follower sleeve is sleeved on the screw structure, the follower sleeve does not rotate but travels synchronously with the stirring head, and its working part forms a clearance fit with the screw; the additive raw materials, in the form of wire or rod, are fed into the gap between the extrusion screw structure and the working part of the follower sleeve through the feed holes on the follower sleeve, and are extruded downward under the action of the screw and deposited and formed under the action of the shoulder of the follower sleeve.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1. The present invention proposes a friction stir additive manufacturing method for an aluminum-steel composite structure. Through interfacial mechanical interlocking and silicon-magnesium co-diffusion metallurgical connection, since the thermal expansion coefficient of the silicon-magnesium co-diffusion layer is between that of aluminum and steel, it effectively alleviates the interfacial residual stress caused by the difference in thermal expansion coefficients of aluminum and steel, and at the same time inhibits the excessive diffusion between aluminum and steel, avoiding the interfacial brittleness caused by the formation of excessive intermetallic compounds;

[0025] 2. The present invention uses a 42% KCl-58% MgCl2 eutectic molten salt mixture as the reaction medium, and its working temperature is significantly lower than that of the conventional NaCl-KCl eutectic molten salt, effectively reducing the thermal damage to the matrix steel, so that the prepared aluminum-steel composite structure can meet the performance requirements without subsequent heat treatment, simplifying the process flow.

[0026] 3. The composite structure manufacturing method proposed by the present invention, which combines mechanical interlocking and metallurgical connection, has excellent process universality. It is not only suitable for the high-quality preparation of aluminum-steel composite structures, but also can be extended to the reliable connection of various heterogeneous material systems such as aluminum-titanium composite structures and magnesium-steel composite structures, and has broad application prospects. Description of the Drawings

[0027] Figure 1 is the process flow diagram of a friction stir additive manufacturing method for an aluminum-steel composite structure according to the present invention;

[0028] Figure 2 is the schematic diagram of a friction stir additive manufacturing method for an aluminum-steel composite structure according to the present invention;

[0029] Figure 3 is the schematic diagram of the surface treatment structure of the steel plate in a friction stir additive manufacturing method for an aluminum-steel composite structure according to the present invention;

[0030] Figure 4 is the schematic diagram of the additive manufacturing tool in a friction stir additive manufacturing method for an aluminum-steel composite structure according to the present invention.

[0031] In the figure, 1 - steel plate, 101 - steel plate surface, 10101 - mechanical interlock structure, 10102 - silicon-magnesium co-permeation metallurgical structure;

[0032] 2 - aluminum alloy;

[0033] 3 - stirring head, 301 - screw structure;

[0034] 4 - follower sleeve, 401 - feed hole, 402 - working part, 403 - shoulder;

[0035] 5 - additive raw material. Specific implementation mode

[0036] Specific implementation mode one: Combined with Figures 1 to 3 To illustrate this implementation mode, a friction stir additive manufacturing method for an aluminum-steel composite structure described in this implementation mode specifically includes the following steps:

[0037] S1: Mechanically grind and clean the surface 101 of the steel plate used for making the aluminum-steel composite structure before additive manufacturing;

[0038] S2: Place the steel plate 1 in a space protected by an inert gas atmosphere, and use mechanical knurling or laser etching to make a mechanical interlock structure 10101 on the steel plate surface 101. By adjusting parameters such as knurling depth / number of times or laser power / focus offset / scanning path, control the morphology of the mechanical interlock structure 10101;

[0039] S3: Place the steel plate 1 with the mechanical interlock structure in a eutectic molten salt mixture of 42% KCl - 58% MgCl2 (by mass fraction) protected by an inert gas atmosphere, and add nano-silica powder, auxiliary flux, reducing agent, etc. to the molten salt mixture. Use a carbon rod as the anode and the steel plate 1 as the cathode for pulsed electric drive-assisted diffusion to achieve the co-permeation 10102 of silicon and magnesium on the steel plate surface;

[0040] S4: Using friction stir additive manufacturing method, deposit multiple layers of aluminum alloy 2 on the steel plate surface 101 until an aluminum-steel composite structure with the required height is obtained. By adjusting parameters such as the feeding rate, layer height, overlap between passes, rotation speed, and traveling speed, control the forming quality of the deposited aluminum alloy 2;

[0041] S5: Use machining subtractive manufacturing to obtain the required transition joint of the aluminum-steel composite structure.

[0042] Specific Embodiment Two: Combining Figure 2 To illustrate this embodiment, for the friction stir additive manufacturing method of an aluminum-steel composite structure described in this embodiment, the specific steps of grinding the steel plate surface 101 before additive manufacturing in S1 are as follows: Use an angle grinder to mechanically grind the steel plate surface 101 until the surface shows metallic luster and has no rust spots.

[0043] Specific Embodiment Three: Combining Figure 2 To illustrate this embodiment, for the friction stir additive manufacturing method of an aluminum-steel composite structure described in this embodiment, the specific steps of cleaning the steel plate surface 101 before additive manufacturing in S1 are as follows: Wipe the steel plate surface 101 with anhydrous ethanol to remove oil stains, then perform alkaline cleaning in a 10% NaOH solution at 80 - 90 °C for 10 minutes, and then transfer it to room temperature for pickling in a 5% HF + 5% HCl solution for 2 minutes. After rinsing with water, dry it.

[0044] Specific Embodiment Four: Combining Figure 3 To illustrate this embodiment, for the friction stir additive manufacturing method of an aluminum-steel composite structure described in this embodiment, the morphologies formed by mechanical knurling or laser etching in S2 include but are not limited to unidirectional wire grooves, multi-directional wire grooves, dot matrices, etc. The structural feature dimensions should be between 2 - 5 mm, and the depth is usually 0.2 - 1.5 mm. The hardness of the mechanical knurling tool used should be significantly greater than that of the steel plate 1 used to manufacture the aluminum-steel composite structure.

[0045] Specific Embodiment Five: For the friction stir additive manufacturing method of an aluminum-steel composite structure described in this embodiment, the addition amount of nano-silica powder in S3 should be 5 - 20% (by mass fraction) of the eutectic molten salt mixture. The auxiliary fluxes used can be optionally but not limited to MgF2, KF, etc., and the addition amount is usually 0.5 - 3.0% (by mass fraction). The reducing agents used can be optionally but not limited to magnesium powder, silicon powder, etc., and the addition amount is usually 1.0 - 5.0% (by mass fraction).

[0046] Specific Embodiment Six: For the friction stir additive manufacturing method of an aluminum-steel composite structure described in this embodiment, the temperature of pulsed electric drive-assisted diffusion in S3 should be set in the range of 500 - 550 °C, and the current density is 50 - 200 mA / cm 2, the pulse frequency is set to 50 Hz, the duty cycle is 0.2 - 0.8, and the infiltration time is 1 - 5 hours to avoid the formation of a loose coating due to too fast precipitation.

[0047] Specific Embodiment Seven: In combination with Figure 2 and Figure 4 describe this embodiment. In the friction stir additive manufacturing method of an aluminum-steel composite structure described in this embodiment, the tool used in S4 for friction stir additive manufacturing includes a stirring head 3, a follower sleeve 4, and an additive raw material 5. Among them, the stirring head 3 rotates at a speed of 100 - 1200 rpm during the additive manufacturing process and travels along the additive manufacturing path at a speed of 200 - 2000 mm / min to achieve multi-pass and multi-layer deposition. The follower sleeve 4 does not rotate but travels synchronously with the stirring head 3. There is an extrusion screw structure 301 on the stirring head 3, which has a clearance fit with the working part 402 of the follower sleeve. The additive raw material 5 is in the form of a wire or a rod, and is fed into the gap between the extrusion screw structure 301 and the working part 402 of the follower sleeve through the feed hole 401 on the follower sleeve, and is extruded downward under the action of the screw 301 and extruded and deposited into shape under the action of the shoulder 403 of the follower sleeve. Its feeding rate, layer height, and overlap amount between passes should be designed to match the mass conservation relationship of the feeding amount and the deposition amount.

[0048] Example

[0049] A friction stir additive manufacturing method for an aluminum-steel composite structure is carried out according to the following steps:

[0050] S1: Select 304 austenitic stainless steel with a thickness of 30 mm. First, mechanically polish its surface with a grinding wheel until the surface shows metallic luster and no rust spots, and then perform surface cleaning. Wipe the surface of the steel plate 101 with anhydrous ethanol to remove oil stains, then alkali wash in a 10% NaOH solution at 80 - 90 °C for 10 minutes, and then transfer it to room temperature and acid wash in a 5% HF + 5% HCl solution for 2 minutes. After rinsing with water, dry it.

[0051] S2: Place the stainless steel plate in an argon protection atmosphere and perform knurling treatment on its surface with a knurling tool having a grid knurling structure with a grid spacing of 2 mm. The knurling depth is 0.5 mm.

[0052] S3: Place the mechanically knurled stainless steel plate in a eutectic molten salt mixture of 42% KCl - 58% MgCl2 (by mass fraction) protected by an argon gas atmosphere. The molten salt mixture is added with 150 g / L of 10 nm silica powder, 75 g / L of MgF2, 50 g / L of KF, and 30 g / L of 40-mesh magnesium powder and mixed evenly. Using a carbon rod as the anode and the mechanically knurled stainless steel plate as the cathode for pulsed electric drive-assisted infiltration, the current density is 120 mA / cm 2, with a pulse frequency of 50 Hz, a duty cycle of 0.5, and a diffusion time of 2 hours, a co-permeation layer of silicon-magnesium on the surface of the stainless-steel plate after mechanical knurling is formed;

[0053] S4: Using the friction stir additive manufacturing method, multiple layers of aluminum alloy are deposited on the surface of the treated stainless-steel plate. The aluminum alloy raw material is 6061 aluminum alloy wire with a diameter of 4 mm. The additive layer height is 3 mm (where the height of the first layer is set separately to 0.5 mm), the layer width is 30 mm, the overlapping width between passes is 5 mm, the rotation speed of the stirring head is 1200 rpm, the traveling speed is 800 mm / min, the wire feeding rate is 4800 mm / min, and the equivalent deposition rate is 9.77 kg / h until an aluminum alloy with a height of not less than 33 mm is deposited on the surface of the stainless-steel plate.

[0054] S5: Using machining subtractive manufacturing, the steel plate area without the aluminum alloy layer around is removed, and the height of the aluminum alloy deposition layer is milled until its deposition layer height is 30 mm to obtain the final required aluminum-steel composite structure transition joint.

[0055] The aluminum-steel composite structure formed by the above process method is quantified, without tissue defects such as pores and cracks. For the aluminum-steel composite uniaxial tensile specimen (the interface is located at the center of the gauge section of the tensile piece) made according to GB / T 228.1-2021 and GB / T 228.2-2015, the measured room-temperature tensile strength is 188 ± 5 MPa, and the high-temperature tensile strength at 250 °C is 66 ± 2 MPa.

[0056] The above is only a preferred embodiment of the present invention and does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art, within the scope of the technical solution of the present invention, can make some changes or modifications to the above-disclosed technical content to obtain equivalent embodiments with equivalent changes. However, as long as it does not depart from the content of the technical solution of the present invention and is based on the technical essence of the present invention, any simple modification, equivalent replacement, and improvement of the above embodiments still fall within the protection scope of the technical solution of the present invention.

Claims

1. A friction stir additive manufacturing method for an aluminum-steel composite structure, characterized in that: The method comprises the following steps: Step 1: Mechanically grinding and cleaning the steel plate surface (101) to be composited of the steel plate (1) before adding materials; Step 2: Preparing a mechanical interlocking structure (10101) on the surface (101) of the steel plate to be composited, specifically comprising: The steel plate (1) is placed in a space protected by an inert gas atmosphere, and a mechanical interlocking structure (10101) is produced on the surface (101) of the steel plate by mechanical knurling or laser etching, and the morphology of the mechanical interlocking structure (10101) is controlled by adjusting the knurling depth / number of times or laser power / defocus amount / scanning path parameters; Step 3: electrically driving silicon-magnesium co-infiltration on the surface of the steel plate with the mechanical interlocking structure (101), specifically comprising: The steel plate (1) having a mechanical interlocking structure is placed in a eutectic molten salt mixture of 42% KCl-58% MgCl2 protected by an inert gas atmosphere, and nano-silicon dioxide powder, auxiliary flux, and reducing agent are added to the molten salt mixture. A pulse electric drive auxiliary diffusion is performed with a carbon rod as an anode and the steel plate (1) as a cathode to achieve a silicon-magnesium co-diffusion metallurgical structure (10102) of silicon-magnesium on the surface of the steel plate; Step 4: Using the friction stir additive manufacturing method, multiple layers of aluminum alloy are deposited to the required height, including: A friction stir additive manufacturing method is used to deposit multiple layers of aluminum alloy (2) on a steel plate surface (101) until an aluminum-steel composite structure of a desired height is obtained, and the forming quality of the deposited aluminum alloy (2) is controlled by adjusting parameters such as feed rate, layer height, overlap between passes, rotation speed, and travel speed; Step 5: Use mechanical processing to obtain the required aluminum-steel composite structure transition joint.

2. The friction stir additive manufacturing method for aluminum-steel composite structures according to claim 1, characterized in that: In step 1, the specific steps of grinding the steel plate surface (101) before material addition are: using an angle grinder to mechanically grind the steel plate surface (101) until the surface has a metallic luster and is free of rust.

3. The friction stir additive manufacturing method for aluminum-steel composite structures according to claim 1, characterized in that: In step 1, the specific steps of cleaning the steel plate surface (101) before material addition are: scrubbing the steel plate surface (101) with anhydrous ethanol to remove oil stains, then alkaline washing in a 10% NaOH solution at 80-90° C. for 10 minutes, then transferring to room temperature and pickling with a 5% HF+5% HCl solution for 2 minutes, and drying after washing and rinsing.

4. The friction stir additive manufacturing method for aluminum-steel composite structures according to claim 1, characterized in that: In step 2, the morphology formed by mechanical knurling or laser etching includes but is not limited to unidirectional grooves, multidirectional grooves, and dot matrix morphology, and its structural feature size should be between 2 and 5 mm, and the depth is usually between 0.2 and 1.5 mm. The hardness of the mechanical knurling tool used should be significantly greater than that of the steel plate (1) used to manufacture the aluminum-steel composite structure.

5. The friction stir additive manufacturing method for aluminum-steel composite structures according to claim 1, characterized in that: In step 3, the amount of nano-silicon dioxide powder added should be 5-20% of the eutectic molten salt mixture, the auxiliary flux used can be optionally but not limited to MgF2, KF, and the addition amount is 0.5-3.0%, and the reducing agent used can be selected from at least one of magnesium powder or silicon powder, and the addition amount is 1.0-5.0%.

6. The friction stir additive manufacturing method for aluminum-steel composite structures according to claim 1, characterized in that: In step 3, the process parameters of pulse electric drive assisted diffusion are: working temperature 500-550°C, current density 50-200 mA / cm 2 , pulse frequency 50Hz, duty cycle 0.2~0.8, diffusion time 1~5 hours.

7. The friction stir additive manufacturing method for aluminum-steel composite structures according to claim 1, characterized in that: In the step 4, the tool used for the friction stir additive manufacturing comprises a stirring head (3), a follower sleeve (4) and an additive raw material (5), wherein: the stirring head (3) is provided with a screw structure (301), the rotation speed is 100 to 1200 rpm, and the screw structure (301) moves at a speed of 200 to 2000 mm / min along the additive manufacturing path to achieve multi-pass multi-layer deposition; the follower sleeve (4) is sleeved on the screw structure (301), the follower sleeve (4) does not rotate but moves synchronously with the stirring head (3), and the working part (402) thereof forms a clearance fit with the screw structure (301); the additive raw material (5), in the form of wire or rod, is fed into the gap between the extrusion screw structure (301) and the working part (402) of the follower sleeve through the feed hole (401) on the follower sleeve, extruded downward under the action of the screw (301) and extruded and deposited under the action of the follower sleeve shoulder (403).

Images