Additive manufacturing method

Abstract

This invention discloses an additive manufacturing method, specifically the following steps: setting laser additive manufacturing equipment parameters and performing pre-welding treatment on a TC4 titanium alloy substrate; defining the hexagonal hard TC4 unit area during the manufacturing process as Area A and the soft TA2 border area as Area B; and then performing additive layering and paving. This method mimics the structure of mother-of-pearl by stacking, inlaying, and interlacing small, flat-plate-like structures in parallel, creating excellent material strength and toughness.

Description

Technical Field

[0001] The present invention relates to the technical field of bionic heterogeneous and isomorphous additive manufacturing, and in particular to an additive manufacturing method. Background Art

[0002] Metals are the most important structural materials, widely used across all industries due to their excellent mechanical, physical, and chemical properties. Continuous advancements in science and technology are placing higher demands on the performance of various types of engineering machinery structures, and metals are facing new challenges in structural design and manufacturing. Alloying and composite methods are being used to continuously improve the overall performance of metals. However, traditional alloying and composite methods fail to consider the effects of the material's microstructure and configuration, failing to fully exploit the synergistic and coupling mechanisms between the different components of the material. Consequently, it is difficult to match the strength and plasticity of the materials, limiting their application.

[0003] In light of this, heterogeneous materials are gaining increasing attention. By integrating the performance advantages of different materials, heterogeneous materials can connect materials with different characteristics and functions into a complete unit, thus matching industrial production applications and improving the overall performance of products. Therefore, the comprehensive performance of heterogeneous materials will exceed that of a single metal structure. Currently, heterogeneous metals are increasingly used in aerospace, shipbuilding, electric power industry and other fields.

[0004] Natural biomaterials (such as spider webs, shells, teeth, and bones) often possess excellent combined mechanical properties, including high strength, high toughness, and low density. This is due to the microstructures they have developed over thousands of years of evolution. These naturally occurring structures hold immense value for modern science and engineering. Designing unique microstructures and configurations that mimic those of natural biomaterials is a viable approach to achieving materials with superior combined mechanical properties.

[0005] Titanium alloys are widely used in aerospace, petrochemical and other fields due to their strong heat resistance, high specific strength, good plasticity, toughness and corrosion resistance. Summary of the Invention

[0006] In response to the above-mentioned technical deficiencies, the present invention aims to provide an additive manufacturing method that mimics the structure of mother-of-pearl, which is composed of a parallel accumulation of small flat-plate structures (mostly hexagonal), stacked and inlaid with each other, and staggered and layered. This produces excellent material strength and toughness, and restores the disorder of biological structures to the greatest extent. This disordered structure has a significant inhibitory effect on the expansion of cracks under load, greatly improving the mechanical properties of the material.

[0007] To solve the above technical problems, the present invention adopts the following technical solution: The present invention provides an additive manufacturing method, comprising the following:

[0008] Set the parameters of the laser additive equipment, perform pre-welding treatment on the TC4 titanium alloy substrate, and load TC4 and TA2 powders into the powder feeding mechanism of the laser additive equipment respectively;

[0009] The hexagonal hard TC4 unit area during the manufacturing process is defined as area A, and the soft TA2 border area is defined as area B;

[0010] Perform additive layered slicing;

[0011] First layer laying: Lay a layer of TC4 titanium alloy powder on the substrate, determine the starting point of the hexagonal area, and scan the powder with a laser. After a complete molten pool is formed, the laser moves horizontally along the X-axis at the starting point, scanning back and forth to form a hexagon. After completion, the laser starts to repeat the process at the starting point of the next hexagonal area. Wait for the melting and sintering of a layer in area A to be completed, blow away the unmelted TC4 titanium alloy powder, lay TA2 pure titanium powder, and start scanning. After the laser acts on the powder and a complete molten pool is formed, the laser moves horizontally along the gap to complete the melting and sintering of the first layer in area B, and blow away the unmelted TA2 pure titanium powder.

[0012] Second layer laying: With the geometric center of the covering layer as the first rotation center, the substrate is rotated by a random angle. The random number of the substrate rotation angle is generated from 6 + (0~1). The first layer laying process is repeated again for powder laying and sintering.

[0013] Repeat the second layer laying process until the nth layer is laid. Each rotation and laying of n layers completes a rotation structure cycle, and the rotation center is changed after laying n layers, where n>2;

[0014] Repeat the above paving process according to the new rotation center, and lay n 2 layer.

[0015] Preferably, the mass fraction distribution of each layer of material is as follows: area A is 95% hard TC4 titanium alloy powder, and area B is 5% soft TA2 pure titanium powder.

[0016] Preferably, setting the parameters of the laser additive equipment includes setting the thickness of each layer and laser parameters, wherein the laser parameters include laser power, spot diameter, and scanning speed.

[0017] Preferably, the spot diameter is 0.3-0.5 mm; and the spot diameter is larger than the hexagonal gap by 0.2 mm;

[0018] The thickness of each layer is 0.1-0.5 mm;

[0019] Laser power is 3-5kW;

[0020] The scanning speed is 30-70 mm / s.

[0021] Preferably, the pre-welding treatment of the TC4 titanium alloy substrate specifically includes the following:

[0022] The substrate size is Φ110 × 23mm. The surface roughness of the TC4 titanium alloy substrate used for additive deposition is machined to 3.2 on a milling machine. Above, and wipe clean with alcohol;

[0023] Before additive manufacturing, the TC4 titanium alloy substrate is heated by a preheating device. The temperature of the TC4 titanium alloy substrate is raised from room temperature to 550-600°C within 60 minutes, and additive manufacturing is performed after keeping the temperature for 15-30 minutes.

[0024] Preferably, during the additive manufacturing cladding process, the TC4 titanium alloy substrate is continuously preheated by a preheating device at a temperature of 300-400°C; at the end of the additive manufacturing process, the temperature of the preheating device is set to a range of 150-200°C, maintained for 30-60 minutes, and then the preheating device is turned off to allow the formed component to cool naturally.

[0025] Preferably, the specific operation of heating the TC4 titanium alloy substrate is as follows:

[0026] The mesh heater is placed on the reference platform of the laser additive equipment, and an insulation layer is placed between the reference platform and the mesh heater. The TC4 titanium alloy substrate is placed on the mesh heater, and a thermocouple is set on the TC4 titanium alloy substrate. The mesh heater is connected to the digital display regulator through an AC contactor. The temperature digital display regulator sets the preheating temperature and monitors the real-time temperature of the formed substrate through the thermocouple to realize the opening or closing of the preheating device.

[0027] Preferably, after every 60 layers, the rotation center is shifted according to the Fibonacci series formula:

[0028]

[0029] Specifically: select any point a1 away from the first rotation center as the center of the circle, use a1 as the radius to make a quarter circle to get the second rotation center, and then use a2 as the rotation radius to make a quarter circle to get the third rotation center, ensuring that the tangents of the two quarter circles coincide at the intersection and the centers are on the same side of the tangents. Then, rotate again with a random number between 6 + (0 and 1) around the new rotation center, rotate 60 times, and repeat this cycle;

[0030] Since the rotation center needs to be constantly rotated and replaced, the laser's motion path needs to be adjusted as a whole according to the new rotation center and new angle relative to the original layer to ensure that each cladding layer overlaps up and down.

[0031] Preferably, the method further includes a heat treatment method for the TC4 titanium alloy substrate after the additive manufacturing is completed, which is specifically as follows:

[0032] First, perform solution treatment, heating the titanium alloy to the high temperature single-phase region and maintaining the temperature constant so that the excess phase can be fully dissolved into the solid solution. The solution temperature is 850℃-950℃, the solution time is 30min-60min, and the cooling method is air cooling.

[0033] Then carry out aging treatment, place the titanium alloy at a certain temperature and keep it for a certain time to allow certain phases to precipitate and the structure to be homogenized. The aging temperature is 480℃-560℃, the aging time is 4h-8h, and the cooling method is air cooling.

[0034] The beneficial effects of this invention lie in designing each additively manufactured layer as a hexagonal biomimetic shell structure, with a certain rotation angle between layers. After processing a certain number of layers, the center of rotation changes, maximizing the resemblance to the disorder of biological structures. This disordered structure significantly hinders the propagation of cracks under load, significantly improving the material's mechanical properties. Furthermore, the designed TC4-TA2 soft-hard interwoven structure simultaneously enhances the material's strength and plasticity, improving its overall mechanical properties. This invention has significant inventive significance and broad development prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 Schematic diagram of welding structure.

[0037] Figure 2 Schematic diagram of processing component equipment.

[0038] Figure 3 Schematic diagram of the processing path.

[0039] Figure 4 Offset the roadmap for the center of rotation.

[0040] Figure 5 This is the temperature-time curve of solution treatment.

[0041] Figure 6 This is the temperature-time curve of aging treatment. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] Embodiment: The present invention provides an additive manufacturing method, specifically a bionic shell TC4-TA2 interwoven titanium and titanium alloy laser selective melting additive manufacturing method; specifically comprising the following:

[0044] The parameters of the laser additive equipment were set, and the TC4 titanium alloy substrate was pre-treated before welding. The prepared TC4 titanium alloy powder and TA2 pure titanium powder were respectively loaded into the powder feeding mechanism of the laser additive equipment (the equipment has two feeding bins for storage). Specifically, TC4 titanium alloy powder and TA2 pure titanium powder with a particle size of 15-53 μm were prepared. Among them, the mass percentage composition of the TC4 titanium alloy powder was as follows: Ti: 89.12%, Al: 6.42%, V: 4.30%, Fe: 0.05%, C: 0.03%, and other substances such as O: 0.08%; the mass percentage composition of the TA2 pure titanium powder was as follows: Fe: 0.30%, C: 0.08%, N: 0.03%, H: 0.015%, O: 0.25%, and Ti: 99.325%.

[0045] The pre-welding treatment of the TC4 titanium alloy substrate specifically includes: setting the substrate size to Φ110 × 23 mm, machining the surface roughness of the TC4 titanium alloy substrate for additive deposition to 3.2 on a milling machine, and Above, and wipe clean with alcohol;

[0046] Before additive manufacturing, the TC4 titanium alloy substrate is heated by a preheating device. The temperature of the TC4 titanium alloy substrate is raised from room temperature to 550-600°C within 60 minutes, and the additive manufacturing is carried out after the temperature is kept at this temperature for 15-30 minutes.

[0047] Among them, setting the parameters of the laser additive equipment includes setting the thickness of each layer and the laser parameters, among which the laser parameters include laser power, spot diameter, and scanning speed; specifically:

[0048] The spot diameter is 0.3 mm;

[0049] The thickness of each layer is 0.1mm;

[0050] The laser power is 5kW;

[0051] The scanning speed is 30 mm / s.

[0052] In addition Figure 2In this paper, a schematic diagram of an existing device is given as a reference. Figure 2 In the figure, 1 is the laser; 2 is the galvanometer; 3 is the laser; 4 is the powder storage chamber; 5 is the powder shaft; 6 is the protective gas; 7 is the TC4 titanium alloy substrate; and 8 is the component.

[0053] The hexagonal hard TC4 unit area in the manufacturing process is defined as area A, and the soft TA2 border area is defined as area B; the spot diameter is larger than the hexagonal gap by 0.2 mm; and area A is 95% hard TC4 titanium alloy powder, and area B is 5% soft TA2 pure titanium powder.

[0054] Perform additive layered slicing;

[0055] First layer laying: Lay a layer of TC4 titanium alloy powder on the substrate, determine the starting point of the hexagonal area, and scan the powder with a laser. After a complete molten pool is formed, the laser moves horizontally along the X-axis at the starting point, scanning back and forth to form a hexagon. After completion, the laser starts to repeat the process at the starting point of the next hexagonal area. Wait for the melting and sintering of a layer in area A to be completed, blow away the unmelted TC4 titanium alloy powder, lay TA2 pure titanium powder, and start scanning. After the laser acts on the powder and a complete molten pool is formed, the laser moves horizontally along the gap to complete the melting and sintering of the first layer in area B, and blow away the unmelted TA2 pure titanium powder.

[0056] Second layer laying: rotate the substrate at a random angle with the geometric center of the covering layer as the first rotation center, and repeat the first layer laying process to lay powder and sinter;

[0057] Repeat the second layer laying process until the 60th layer is laid. After every 60 layers, the rotation center changes, where n is preferably 60;

[0058] Repeat the above laying process according to the new rotation center, laying a total of 360 layers;

[0059] The random number of the substrate rotation angle is generated from 6 + (0~1), and a rotation structure cycle is completed every 60 layers. The rotation center is changed after 60 layers are laid.

[0060] After every 60 layers, the rotation center is shifted according to the Fibonacci series formula:

[0061]

[0062] Specifically: select any point a1 away from the first rotation center as the center of the circle, use a1 as the radius to make a quarter circle to get the second rotation center, and then use a2 as the rotation radius to make a quarter circle to get the third rotation center, ensuring that the tangents of the two quarter circles coincide at the intersection and the centers are on the same side of the tangents. Then, rotate again with a random number between 6 + (0 and 1) around the new rotation center, rotate 60 times, and repeat this cycle;

[0063] Since the rotation center needs to be constantly rotated and replaced, the laser's motion path needs to be adjusted as a whole according to the new rotation center and new angle relative to the original layer to ensure that each cladding layer overlaps up and down.

[0064] Furthermore, the components after additive manufacturing are heat treated as follows:

[0065] First, the solution treatment is carried out, that is, the titanium alloy is heated to the high temperature single-phase region and kept at a constant temperature so that the excess phase is fully dissolved into the solid solution. The solution temperature is 920℃, the solution time is 55min, and the cooling method is air cooling.

[0066] Then carry out aging treatment, that is, keep the titanium alloy at a certain temperature for a certain time to allow certain phases to precipitate and the structure to be homogenized. The aging temperature is 480℃, the aging time is 7.5h, and the cooling method is air cooling.

[0067] Finally, the component is separated from the substrate, the surface is cleaned, and the required sample is obtained.

[0068] In the above process, during the additive manufacturing cladding process, the TC4 titanium alloy substrate is continuously preheated by the preheating device at a temperature of 300-400°C; at the end of the additive manufacturing process, the temperature of the preheating device is set to a range of 150-200°C, maintained for 30-60 minutes, and then the preheating device is turned off to allow the formed component to cool naturally;

[0069] The specific operation of heating the TC4 titanium alloy substrate is as follows:

[0070] A mesh heater is placed on the reference platform of the laser additive equipment, an insulating layer is placed between the reference platform and the mesh heater, a TC4 titanium alloy substrate is placed on the mesh heater, and a thermocouple is set on the TC4 titanium alloy substrate; the mesh heater is connected to a digital display regulator through an AC contactor, the temperature digital display regulator sets the preheating temperature, and the real-time temperature of the formed substrate is monitored by the thermocouple to realize the opening or closing of the preheating device.

[0071] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. An additive manufacturing method, characterized in that: These include: Set the parameters of the laser additive equipment, perform pre-welding treatment on the TC4 titanium alloy substrate, and load TC4 and TA2 powders into the powder feeding mechanism of the laser additive equipment respectively; The hexagonal hard TC4 unit area during the manufacturing process is defined as area A, and the soft TA2 border area is defined as area B; Perform additive layered slicing; First layer laying: Lay a layer of TC4 titanium alloy powder on the substrate, determine the starting point of the hexagonal area, and scan the powder with a laser. After a complete molten pool is formed, the laser moves horizontally along the X-axis at the starting point, scanning back and forth to form a hexagon. After completion, the laser starts to repeat the process at the starting point of the next hexagonal area. Wait for the melting and sintering of a layer in area A to be completed, blow away the unmelted TC4 titanium alloy powder, lay TA2 pure titanium powder, and start scanning. After the laser acts on the powder and a complete molten pool is formed, the laser moves horizontally along the gap to complete the melting and sintering of the first layer in area B, and blow away the unmelted TA2 pure titanium powder. Second layer laying: With the geometric center of the covering layer as the first rotation center, the substrate is rotated by a random angle. The random number of the substrate rotation angle is generated from 6 + (0~1) degrees. The first layer laying process is repeated again for powder laying and sintering. Repeat the second layer laying process until the nth layer is laid. Each rotation and laying of n layers completes a rotation structure cycle, and the rotation center is changed after laying n layers, where n>2; Repeat the above paving process according to the new rotation center, and lay n 2 layer.

2. The additive manufacturing method according to claim 1, wherein: The mass fraction distribution of each layer material is as follows: Area A is 95% hard TC4 titanium alloy powder, and Area B is 5% soft TA2 pure titanium powder.

3. The additive manufacturing method according to claim 1, wherein: Setting the parameters of the laser additive equipment includes setting the thickness of each layer and the laser parameters, where the laser parameters include laser power, spot diameter, and scanning speed.

4. The additive manufacturing method according to claim 3, wherein: The spot diameter is 0.3-0.5 mm; and the spot diameter is larger than the hexagonal gap by 0.2 mm; The thickness of each layer is 0.1-0.5 mm; Laser power is 3-5kW; The scanning speed is 30-70 mm / s.

5. The additive manufacturing method according to claim 1, wherein: The pre-welding treatment of TC4 titanium alloy substrate includes the following: The substrate size is Φ110 × 23mm. The surface roughness of the TC4 titanium alloy substrate used for additive deposition is machined to 3.2 on a milling machine. Above, and wipe clean with alcohol; Before additive manufacturing, the TC4 titanium alloy substrate is heated by a preheating device. The temperature of the TC4 titanium alloy substrate is raised from room temperature to 550-600°C within 60 minutes, and additive manufacturing is performed after keeping the temperature for 15-30 minutes.

6. The additive manufacturing method according to claim 1, wherein: During the additive manufacturing cladding process, the TC4 titanium alloy substrate is continuously preheated by a preheating device at a temperature of 300-400°C. At the end of the additive manufacturing process, the temperature of the preheating device is set to the range of 150-200°C, maintained for 30-60 minutes, and then the preheating device is turned off to allow the formed component to cool naturally.

7. An additive manufacturing method according to claim 5 or 6, characterized in that: The specific operation of heating the TC4 titanium alloy substrate is as follows: A mesh heater is placed on the reference platform of the laser additive equipment, an insulation layer is placed between the reference platform and the mesh heater, a TC4 titanium alloy substrate is placed on the mesh heater, and a thermocouple is set on the TC4 titanium alloy substrate; The mesh heater is connected to the digital display regulator through an AC contactor. The temperature digital display regulator sets the preheating temperature and monitors the real-time temperature of the forming substrate through a thermocouple to realize the opening or closing of the preheating device.

8. The additive manufacturing method according to claim 1, wherein: After every 60 layers, the rotation center is shifted according to the Fibonacci series formula: Specifically: select any point a1 away from the first rotation center as the center of the circle, use a1 as the radius to make a quarter circle to get the second rotation center, and then use a2 as the rotation radius to make a quarter circle to get the third rotation center, ensuring that the tangents of the two quarter circles coincide at the intersection and the centers are on the same side of the tangents. Then, rotate again with a random number between 6 + (0 and 1) around the new rotation center, rotate 60 times, and repeat this cycle; Since the rotation center needs to be constantly rotated and replaced, the laser's motion path needs to be adjusted as a whole according to the new rotation center and new angle relative to the original layer to ensure that each cladding layer overlaps up and down.

9. The additive manufacturing method according to claim 1, wherein: It also includes a heat treatment method for the TC4 titanium alloy substrate after additive manufacturing, as follows: First, perform solution treatment, heating the titanium alloy to the high temperature single-phase region and maintaining the temperature constant so that the excess phase can be fully dissolved into the solid solution. The solution temperature is 850℃-950℃, the solution time is 30min-60min, and the cooling method is air cooling. Then carry out aging treatment, place the titanium alloy at a certain temperature and keep it for a certain time to allow certain phases to precipitate and the structure to be homogenized. The aging temperature is 480℃-560℃, the aging time is 4h-8h, and the cooling method is air cooling.

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