Method for improving metal forming by friction stir deposition based on thermoplastic metal confinement deposition

Abstract

This invention provides a method for improving the forming of friction stir deposited metals based on thermoplastic metal confinement deposition. A confinement space is constructed on a substrate using a confinement component, and a friction stir deposition component extends into this space to perform friction stir deposition. Through the close cooperation between the friction stir deposition component and the confinement component, the thermoplastic metal deposited below the friction stir deposition component is confined, preventing it from freely overflowing to both sides of the component, thus achieving controllable deposition of the thermoplastic metal. This invention solves the technical problems in traditional friction stir deposition where the deposited thermoplastic metal freely overflows from below the component to both sides, resulting in uncontrollable metal forming, irregular shapes, obvious layer-by-layer accumulation marks, and the need for extensive post-deposition machining. This invention significantly improves the forming quality and accuracy of friction stir deposited metal components.

Description

Technical Field

[0001] This invention belongs to the field of tribo-stirred deposition technology, specifically relating to a method for improving the forming of tribo-stirred deposited metals based on thermoplastic metal confinement deposition. Background Technology

[0002] Friction stir deposition (FSD) is a metal solid-state deposition technique based on the principle of friction stir. The metal to be deposited is thermoplasticized under intense friction stir, and the thermoplastic metal is uniformly spread under pressure beneath a high-speed rotating friction stir deposition component, forming a dense deposition layer. Subsequently, the next layer of thermoplastic metal is applied on top of the previous deposition layer, and this process is repeated layer by layer to ultimately form a three-dimensional solid component. The core characteristic of friction stir deposition is that the metal material does not melt during the entire deposition process, effectively avoiding various defects caused by metal melting and solidification in traditional cladding deposition, such as porosity, hot cracks, compositional segregation, alloy element burn-off, metal oxidation, and oxide inclusions. Simultaneously, the intense plastic deformation during friction stir deposition refines the grains, forming a uniform, fine equiaxed grain structure, enabling the mechanical properties of the deposited metal to reach or approach the level of forgings. Furthermore, this process does not produce smoke or splashes, making it environmentally friendly, and its deposition efficiency is higher than traditional cladding deposition, showing broad application prospects in the forming of large structural components in aerospace and other fields.

[0003] However, during the friction stir deposition process, the thermoplastic metal is not laterally restrained. Under the combined action of the dynamic pressure generated by the upsetting of the friction stir deposition component and the continuous feeding of the metal to be deposited, the thermoplastic metal spread under the friction stir deposition component will continue to overflow freely to both sides, resulting in uncontrollable and irregular shape of the deposited metal, and obvious traces of layer-by-layer accumulation ([1] Liu Xin, Li Xiaoqiang, Hao Jiakang, et al. Research progress on high-performance metal friction stir deposition additive manufacturing technology [J]. Rare Metal Materials and Engineering, 2025, 54(11):2964-2984; [2] Patent application entitled "A flow friction additive manufacturing device and additive manufacturing method" (publication number CN109202272A)). Therefore, it is often necessary to perform a lot of machining on the metal components of friction stir deposition in order to meet the forming accuracy requirements. How to apply restraint to the thermoplastic metal of friction stir deposition so that it can be deposited in a controllable manner directly under the friction stir deposition component, thereby improving the deposition forming quality, has become a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a method for improving the forming of friction stir deposited metal based on thermoplastic metal confinement deposition. A confinement space is constructed by using confinement components, and a friction stir depositing component is inserted into the confinement space for friction stir deposition. Lateral compressive stress is applied to the thermoplastic deposited metal spread below the friction stir depositing component using the sidewalls of the confinement space, restricting its free overflow to both sides and forcing the thermoplastic metal to be deposited controllably directly below the depositing component. The confinement components act as a deposition mold, and their lateral confinement significantly improves the forming quality and accuracy of the friction stir deposited metal component. Furthermore, by adjusting the shape and size of the confinement space, the final forming of the friction stir deposited metal can be flexibly controlled.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for improving stir-friction deposition metal forming based on thermoplastic metal confinement deposition includes the following steps: (1) A restraint space is constructed by using restraint components to enclose the substrate. The restraint components have a side surface and a lower surface, and the lower surface is in close contact with the upper surface of the substrate. (2) The friction stir deposition component is inserted into the confinement space, so that the sidewall of the confinement space surrounds the friction stir deposition component, and there is a preset gap between the bottom end face of the friction stir deposition component and the upper surface of the substrate; the feeding speed of the metal to be deposited is controlled so that the volume of the thermoplastic metal deposited below the friction stir deposition component is not less than the product of the area of ​​the bottom end face of the friction stir deposition component and the preset gap, so that the thermoplastic metal fills the preset gap between the bottom end face of the friction stir deposition component and the upper surface of the substrate. (3) After the thermoplastic deposited metal fills the preset gap between the bottom end face of the friction stir deposition component and the upper surface of the substrate, it comes into contact with the side wall of the confinement space and is constrained by the lateral compressive stress applied by the side wall to limit the free overflow of the thermoplastic deposited metal to both sides of the friction stir deposition component. (4) The stirring friction deposition component moves along a preset path in the confinement space and deposits thermoplastic metal layer by layer to fill the confinement space. After filling to a specified height, the stirring friction deposition component is lifted and the confinement component is removed to obtain a stirring friction confinement deposition component with flat sidewalls that conforms to the shape of the confinement space.

[0006] The confinement space described in step (1) is open at the top so that the stirring friction deposition component can extend from above and move within the confinement space.

[0007] The thermoplasticization temperature of the restraint component material in step (1) is higher than that of the metal to be deposited, and the melting point of the restraint component material is higher than that of the metal to be deposited.

[0008] The substrate mentioned in step (1) is selected from magnesium alloy, aluminum alloy, titanium alloy, copper alloy, steel or high entropy alloy.

[0009] The stirring friction deposition component described in step (2) rotates to generate heat through friction so that the metal to be deposited reaches a thermoplastic state.

[0010] The metal to be deposited in step (2) is selected from magnesium alloy, aluminum alloy, titanium alloy, copper alloy, steel or high entropy alloy.

[0011] The metal to be deposited in step (2) is fed in the form of rods, wires or powder.

[0012] The distance between the rotation center line of the stirring friction deposition component and the side wall of the confinement space in step (3) shall not be less than 1 / 2 of the radial dimension of the stirring friction deposition component.

[0013] The preset path of the stirring friction deposition component in step (4) is selected from a straight path, a ring path, a rectangular path, a triangular path, an elliptical path, an arc path, or a combination of at least two of the above paths.

[0014] The specified height in step (4) is less than or equal to the height of the top of the sidewall of the restraint space relative to the upper surface of the substrate.

[0015] Compared with the prior art, the present invention has the following advantages: 1) This invention employs a restraint component to enclose a restraint space on a substrate. The sidewalls of this restraint space apply lateral compressive stress to the thermoplastic metal, which has an overflow tendency, spread beneath the friction stir deposition component, restricting its free overflow to both sides. This allows for controlled deposition of the thermoplastic metal directly beneath the friction stir deposition component. The restraint component acts as a deposition mold, significantly improving the forming quality and dimensional accuracy of the friction stir deposited metal component by laterally restraining the deposited thermoplastic metal. This, in turn, helps reduce subsequent subtractive processing steps such as milling and trimming. This is of great significance for improving the utilization rate and production efficiency of deposited materials and reducing manufacturing costs.

[0016] 2) This invention constructs a confinement space by using confinement components, and performs friction stir deposition within this space. By adjusting the shape of the confinement space constructed by the confinement components on the substrate, the final shape of the friction stir deposited metal can be controlled, thereby achieving precise friction stir deposition forming of components with complex structures. Furthermore, the confinement components are easy to assemble and disassemble, reusable, and offer high process flexibility and low cost, making them suitable for large-scale industrial production. Attached Figure Description

[0017] Figure 1This is a schematic diagram of the stirring and frictional confinement deposition in an annular confinement space according to Embodiment 1 of the present invention.

[0018] Figure 2 This is a schematic diagram of the sample effect of stirring and frictional depositing in the annular restraint space after the restraint components are removed in Embodiment 1 of the present invention.

[0019] Figure 3 This is a schematic diagram of the sample obtained by conventional stirring and friction deposition along a circular path.

[0020] Figure 4 This is a schematic diagram of the stirring and frictional confinement deposition in a rectangular annular confinement space according to Embodiment 2 of the present invention.

[0021] Figure 5 This is a schematic diagram of the sample effect of stirring and frictional depositing in the rectangular annular restraint space after the restraint components are removed in Embodiment 2 of the present invention.

[0022] Figure 6 This is a schematic diagram of the sample obtained by conventional stirring and friction deposition along a rectangular ring path.

[0023] In the figure: 1. First substrate; 2. First friction stir deposition component; 3. First metal to be deposited; 4. First outer restraint component; 5. First inner restraint component; 6. First deposited metal; 7. Second substrate; 8. Second friction stir deposition component; 9. Second metal to be deposited; 10. Second outer restraint component; 11. Second inner restraint component; 12. Second deposited metal. Detailed Implementation

[0024] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] Example 1: Refer to Figure 1 Aluminum alloy-steel dissimilar metal composite components were prepared by friction-stirring deposition within a circular confinement space. A first outer confinement component 4 and a first inner confinement component 5, both made of 45# steel, were used. The first outer confinement component 4 consisted of two interlocking annular baffles, each 5 mm thick, 18 mm high, and with an inner diameter of 64 mm. The first inner confinement component 5 was a cylinder with a diameter of 32 mm and a height of 18 mm. The first substrate 1 was made of DP600 steel, with dimensions of 120 mm × 80 mm × 3 mm.

[0026] A method for improving stir-friction deposition metal forming based on thermoplastic metal confinement deposition includes the following steps: Step 1: Grind and polish the surfaces of the first substrate 1, the first outer restraint member 4, and the first inner restraint member 5; wipe and clean the surfaces of the first substrate 1, the first outer restraint member 4, and the first inner restraint member 5 with chemical reagents; construct an annular restraint space on the upper surface of the first substrate 1 by using the first outer restraint member 4 and the first inner restraint member 5. Specifically, sandpaper or an angle grinder is used to mechanically polish the surfaces of the first substrate 1, the first outer restraint member 4, and the first inner restraint member 5 to remove the oxide film; organic solvents or cleaning agents are used to wipe the polished surfaces to remove impurities, oil, and dust adhering to the surfaces; wherein, the organic solvent used is acetone or anhydrous ethanol solution; Step 2: Select a first friction stir deposition component 2 made of WC-Co hard alloy. The diameter of the first friction stir deposition component 2 is 16 mm, the axial length is 20 mm, and a square through hole with a side length of 5 mm is provided in the middle along the axis. Fix the first substrate 1, the first outer restraint component 4, and the first inner restraint component 5 as a whole on the worktable of the friction stir deposition equipment. Then, extend the first friction stir deposition component 2 into the restraint space, adjust the distance between the first friction stir deposition component 2 and the upper surface of the first substrate 1 to 0.3 mm, start the friction stir deposition equipment, and set the rotation speed of the first friction stir deposition component 2 to 500 rpm. Select a 7075 aluminum alloy square rod as the first metal to be deposited 3. The bottom side length of the first metal to be deposited 3 is 5 mm × 5 mm. mm, the first metal to be deposited 3 is fed into the square through hole of the first friction stir deposition component 2. The first friction stir deposition component 2 drives the first metal to be deposited 3 to rotate. The first metal to be deposited 3 rubs against the first substrate 1, causing the temperature of the first metal to be deposited 3 to rise and enter the thermoplastic state, and then deposited in the gap between the bottom end face of the first friction stir deposition component 2 and the first substrate 1. After the thermoplastic deposited metal fills the gap between the bottom end face of the first friction stir deposition component 2 and the first substrate 1, it contacts the sidewalls of the first outer restraint component 4 and the first inner restraint component 5. The sidewalls of the first outer restraint component 4 and the first inner restraint component 5 apply uniform lateral compressive stress to the thermoplastic deposited metal. This lateral compressive stress effectively restricts the thermoplastic deposited metal from freely overflowing to both sides of the first friction stir deposition component 2, thereby confining the thermoplastic deposited metal directly below the first friction stir deposition component 2, realizing the controllable deposition of thermoplastic metal. Step 3: A pre-set annular deposition path is provided for the first friction stir deposition component 2. The traveling speed of the first friction stir deposition component 2 is 100 mm / min, and the thickness of each deposition layer is controlled at 0.3 mm. After the first friction stir deposition component 2 completes one annular deposition along the pre-set annular deposition path, the first friction stir deposition component 2 is raised by 0.3 mm, and then the next annular deposition layer is deposited. The above deposition process is repeated until the first deposited metal 6 reaches the specified height of 9 mm. After the friction stir confinement deposition is completed, the first friction stir deposition component 2 is retracted and the equipment is turned off. After the first deposited metal 6, the first substrate 1, the first outer confinement component 4 and the first inner confinement component 5 are cooled to room temperature, the first outer confinement component 4 and the first inner confinement component 5 are removed to obtain the target friction stir confinement deposition component.

[0027] Figure 2 This is a schematic diagram showing the effect of sample deposition through stirring and friction within the annular restraint space after the removal of the first outer restraint component 4 and the first inner restraint component 5. Testing revealed that the sample has a regular shape, smooth and flat side surfaces, and an external dimensional error ≤0.1 mm.

[0028] Figure 3 This is a schematic diagram of the sample obtained by conventional agitation-friction deposition along a circular path. As can be seen, without restraint components, the obtained sample has an irregular shape, uneven side surfaces, and obvious flash and overflow.

[0029] Example 2: Refer to Figure 4 Magnesium alloy components were fabricated by friction-stirred deposition within a rectangular annular confinement space. Specifically, a second outer confinement component 10 and a second inner confinement component 11, made of 45# steel, were selected. The second outer confinement component 10 consisted of two interlocking baffles, each 5 mm thick. The inner wall of the second outer confinement component 10 had a length dimension of 76 mm, a width dimension of 64 mm, and a height of 18 mm. The four edges along the height direction on both the inner and outer walls of the second outer confinement component 10 were rounded with a radius of 24 mm. The second inner confinement component 11 was a cuboid with a height of 18 mm, a length of 44 mm, and a width of 32 mm. The four edges along the height direction on the sidewall of the second inner confinement component 11 were rounded with a radius of 8 mm. The second substrate 7 was made of AE44 magnesium alloy, with dimensions of 120 mm × 80 mm × 3 mm.

[0030] A method for improving stir-friction deposition metal forming based on thermoplastic metal confinement deposition includes the following steps: Step 1: Polish the surfaces of the second substrate 7, the second outer restraint member 10, and the second inner restraint member 11; wipe the surfaces of the second substrate 7, the second outer restraint member 10, and the second inner restraint member 11 with a chemical reagent; construct a rectangular-annular restraint space on the upper surface of the second substrate 7 by using the second outer restraint member 10 and the second inner restraint member 11. Specifically, the oxide film on the surfaces of the second substrate 7, the second outer restraint member 10, and the second inner restraint member 11 is removed by mechanical sanding with sandpaper or an angle grinder; the sanded surfaces are then wiped with an organic solvent or cleaning agent to remove adhering impurities, oil, and dust. The organic solvent used is acetone or anhydrous ethanol solution. Step 2: Select a second friction stir deposition component 8 made of WC-Co hard alloy. The diameter of the second friction stir deposition component 8 is 16 mm, the axial length is 20 mm, and a square through hole with a side length of 5 mm is provided in the middle along the axis. Fix the second substrate 7, the second external restraint component 10, and the second internal restraint component 11 as a whole on the worktable of the friction stir deposition equipment, and then extend the second friction stir deposition component 8 into the restraint space. Adjust the distance between the second friction stir deposition component 8 and the surface of the second substrate 7 to 0.5 mm, start the friction stir deposition equipment, and set the rotation speed of the second friction stir deposition component 8 to 400 rpm. Select an AE44 magnesium alloy square rod as the second metal to be deposited 9. The bottom side length of the second metal to be deposited 9 is 5 mm × 5 mm. The second metal to be deposited, 9, is fed into the square through-hole of the second friction stir deposition component 8. The second friction stir deposition component 8 drives the second metal to be deposited, 9, to rotate. The second metal to be deposited, 9, rubs against the second substrate 7, causing the temperature of the second metal to be deposited, 9, to rise and enter a thermoplastic state, and then deposits in the gap between the bottom end face of the second friction stir deposition component 8 and the second substrate 7. After the thermoplastic deposited metal fills the gap between the bottom end face of the second friction stir deposition component 8 and the second substrate 7, it contacts the sidewalls of the second outer restraint component 10 and the second inner restraint component 11. The sidewalls of the second outer restraint component 10 and the second inner restraint component 11 apply uniform lateral compressive stress to the thermoplastic deposited metal. This lateral compressive stress effectively restricts the thermoplastic deposited metal from freely overflowing to both sides of the second friction stir deposition component 8, thereby confining the thermoplastic deposited metal directly below the second friction stir deposition component 8, and realizing the controllable deposition of thermoplastic metal. Step 3: A rectangular annular deposition path is preset for the second friction stir deposition component 8. The traveling speed of the second friction stir deposition component 8 is 100 mm / min, and the thickness of each deposition layer is controlled at 0.5 mm. After the second friction stir deposition component 8 completes a layer deposition along the preset rectangular annular deposition path, the second friction stir deposition component 8 is raised by 0.5 mm before the next layer deposition is carried out. The above deposition process is repeated until the second deposited metal 12 reaches the specified height of 10 mm. After the entire friction stir confinement deposition process is completed, the second friction stir deposition component 8 is retracted and the equipment is turned off. After the second deposited metal 12, the second substrate 7, the second outer confinement component 10 and the second inner confinement component 11 are cooled to room temperature, the second outer confinement component 10 and the second inner confinement component 11 are removed to obtain the target deposited component.

[0031] Figure 5 This is a schematic diagram of the effect of stir-friction confinement deposition of a sample in a rectangular annular confinement space after the removal of the second outer confinement component 10 and the second inner confinement component 11. By testing the AE44 magnesium alloy stir-friction confinement deposition sample prepared in this embodiment, it can be found that the sample's outer contour dimension error is ≤0.1 mm, its side surface is smooth and flat, and there are no traces of thermoplastic metal overflow.

[0032] Figure 6 The diagram shows the sample effect of conventional stir-friction deposition on a rectangular ring path. It can be seen that without restraints, thermoplastic metal overflows from the deposition path to both sides, which seriously affects the sample forming accuracy.

[0033] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for improving metal forming by friction stir deposition based on thermoplastic metal confinement deposition, characterized in that, Includes the following steps: (1) A restraint space is constructed by using restraint components to enclose the substrate. The restraint components have a side surface and a lower surface, and the lower surface is in close contact with the upper surface of the substrate. (2) The friction stir deposition component is inserted into the confinement space, so that the sidewall of the confinement space surrounds the friction stir deposition component, and there is a preset gap between the bottom end face of the friction stir deposition component and the upper surface of the substrate; the feeding speed of the metal to be deposited is controlled so that the volume of the thermoplastic metal deposited below the friction stir deposition component is not less than the product of the area of ​​the bottom end face of the friction stir deposition component and the preset gap, so that the thermoplastic metal fills the preset gap between the bottom end face of the friction stir deposition component and the upper surface of the substrate. (3) After the thermoplastic deposited metal fills the preset gap between the bottom end face of the friction stir deposition component and the upper surface of the substrate, it comes into contact with the side wall of the confinement space and is constrained by the lateral compressive stress applied by the side wall to limit the free overflow of the thermoplastic deposited metal to both sides of the friction stir deposition component. (4) The stirring friction deposition component moves along a preset path in the confinement space and deposits thermoplastic metal layer by layer to fill the confinement space. After filling to a specified height, the stirring friction deposition component is lifted and the confinement component is removed to obtain a stirring friction confinement deposition component with flat sidewalls that conforms to the shape of the confinement space.

2. The method of claim 1, wherein: The confinement space described in step (1) is open at the top so that the stirring friction deposition component can extend from above and move within the confinement space.

3. The method of claim 1, wherein: The thermoplasticization temperature of the restraint component material in step (1) is higher than that of the metal to be deposited, and the melting point of the restraint component material is higher than that of the metal to be deposited.

4. The method of claim 1, wherein: The substrate mentioned in step (1) is selected from magnesium alloy, aluminum alloy, titanium alloy, copper alloy, steel or high entropy alloy.

5. The method of claim 1, wherein: The stirring friction deposition component described in step (2) rotates to generate heat through friction so that the metal to be deposited reaches a thermoplastic state.

6. The method of claim 1, wherein: The metal to be deposited in step (2) is selected from magnesium alloy, aluminum alloy, titanium alloy, copper alloy, steel or high entropy alloy.

7. The method of claim 1, wherein: The metal to be deposited in step (2) is fed in the form of rods, wires or powder.

8. The method of claim 1, wherein: The distance between the rotation center line of the stirring friction deposition component and the side wall of the confinement space in step (3) shall not be less than 1 / 2 of the radial dimension of the stirring friction deposition component.

9. The method of claim 1, wherein: The preset path of the stirring friction deposition component in step (4) is selected from a straight path, a ring path, a rectangular path, a triangular path, an elliptical path, an arc path, or a combination of at least two of the above paths.

10. The method according to claim 1, characterized in that: The specified height in step (4) is less than or equal to the height of the top of the sidewall of the restraint space relative to the upper surface of the substrate.

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