An additive manufacturing method for inhibiting cracking during forming of a metal component

Abstract

This invention relates to the field of additive manufacturing of metallic materials, specifically disclosing an additive manufacturing method for suppressing cracking during the forming process of metal components. The method includes: designing a part model and a shell model of the metallic material, merging them into a single integrated model; slicing the model layer by layer using slicing software; and 3D printing the metal powder using additive manufacturing techniques such as SLM (Surface Mount Technology), ultimately obtaining a crack-free or low-crack metallic material structural component. This invention facilitates high-throughput experiments on novel materials to quickly obtain appropriate printing parameters, significantly expands the additive manufacturing process window for novel metallic materials, and is beneficial for preparing crack-free or low-crack metallic material structural components. It is simple to operate and low in cost.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing of metal materials technology, and specifically relates to an additive manufacturing method for suppressing cracking during the forming process of metal components. Background Technology

[0002] The research and application of new materials and processes play a crucial role in the advancement of high-tech industries, especially in the aerospace sector. The fabrication of metallic structural components in the aerospace industry primarily relies on traditional technologies, including ingot metallurgy, precision casting, thermal processing, and additive manufacturing. While each method has its advantages, additive manufacturing clearly possesses the greatest development potential. This method overcomes limitations in size and molds, allowing the fabrication of complex-shaped metallic parts and eliminating subsequent machining and joining processes. Furthermore, additive manufacturing uses powdered raw materials for melting and forming, recyclable powders, and utilizes numerical calculations for material mechanics analysis and topology optimization to achieve weight reduction while maintaining material strength.

[0003] However, additive manufacturing of metallic materials faces a series of challenges. One major issue is the determination of process parameters. This involves costly, high-throughput testing and batch verification, which is both costly and inefficient. Rapid solidification rates can lead to defects such as cracking and keyholes within the molten pool, severely narrowing the process window. Furthermore, if unsuitable parameters are discovered during the parameter determination phase, the entire batch typically needs to be discarded, resulting in significant economic and time costs. Consequently, currently, only a few dozen types of metallic materials and their corresponding process parameters are readily available for additive manufacturing. Given this context, reducing the content of internal defects in materials and expanding the process window becomes a crucial issue in this field. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an additive manufacturing method for suppressing cracking during the forming process of metal components. This method controls powder erosion on the outer side of the modeling area and employs an outer protection zone modeling approach during material forming to ensure the internal metal material can be formed smoothly without protrusion. This method alleviates stress concentration and stress release caused by material protrusion, thereby significantly reducing the content of defects such as porosity and cracks in the material and greatly expanding the processing window for additive manufacturing of metal structural components.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention provides an additive manufacturing method for suppressing cracking during the forming process of metal components, the method comprising the following steps:

[0007] Step 1: Use 3D modeling software to design the metal material structural component model and add the necessary support design;

[0008] Step 2: Set the manufacturing process parameters for the metal material structural component model and the support model, such as processing power, scanning speed, scanning spacing, layer thickness, etc., and slice the model layer by layer according to the designed layer thickness;

[0009] Step 3: Add a shell-shaped area around the structural component model area as a protected area;

[0010] Step 4: Set the manufacturing process parameters for the outer protection zone. These parameters can be different from those for the internal structural component model. However, it is necessary to ensure that the energy density input of the outer protection zone is less than or equal to that of the internal structural component model area. The purpose is to absorb the powder adjacent to the outside of the modeling area.

[0011] Step 5: Sieve out the metal powder of the corresponding layer thickness and dry it to avoid interference from impurities such as water molecules in the air to the printing process;

[0012] Step 6: Using additive manufacturing process, powder is 3D printed on the substrate plane using an external heat source. During the printing process, the outer shell area of ​​the material is printed first, followed by the inner area, and finally a metal material structure with no or few cracks is obtained.

[0013] As a further explanation of the present invention, the metallic material includes at least one of intermetallic compound materials and titanium metal materials. Preferably, the composition of the metallic material structural component is at least one of Ti-48Al-2Nb-2Cr, Ti-45Al-2Cr-5Nb, Ti-43.5Al-4Nb-1Mo-0.1B, and Ti-45.5Al-4Cr-2.5Nb.

[0014] As a further illustration of the present invention, the metal material structural component may have additional elements added, including V, Y, Si, and C.

[0015] As a further explanation of the present invention, the heat source for additive manufacturing includes one of a laser heat source, a plasma heat source, or an electron beam heat source, and the additive manufacturing process includes one of selective laser melting, laser delamination melting, electron beam melting, and direct laser deposition.

[0016] As a further explanation of the present invention, in step 1, the 3D modeling software includes one of UG, Cero, Solidworks, Catia, and Magic.

[0017] As a further explanation of the present invention, in step 2, the process parameters include laser or electron beam focusing diameter, substrate heating temperature, processing power, scanning rate, scanning strategy, scanning spacing, and powder layer thickness; wherein, preferably, the laser or electron beam focusing diameter is 60-500 μm; preferably, the substrate heating temperature is 100-300℃; preferably, the heating power is 50-500 W; preferably, the scanning rate is 10-1000 mm / s; preferably, the scanning strategy is a unidirectional scanning strategy, a unidirectional rotating alternating scanning strategy, a reciprocating scanning strategy, a reciprocating rotating alternating strategy, a checkerboard scanning strategy, or a 67° rotating scanning strategy; the scanning spacing is 50-200 μm; and the powder layer thickness is 20-250 μm.

[0018] As a further explanation of the present invention, in step 2, the energy density range of the metal material structural component model is 10 to 1000 J / mm². 3 The formula for calculating energy density is: heating power / (scanning rate × powder layer thickness × scanning distance).

[0019] As a further explanation of the present invention, in step 3, the width of the outer protection zone of the structural component model is not less than 2mm, and its height is consistent with the height of the inner structural component model. Preferably, the width of the outer protection zone is 2.5 to 5mm.

[0020] As a further explanation of the present invention, in step 5, the particle size distribution of the raw material metal powder used in the metal material structural component conforms to a normal distribution, and its average particle size should correspond to the thickness of the software slice layer of the material, and the two should be similar or consistent; preferably, the material layer thickness is 'a', where 'a' is greater than zero, and the particle size D50 of the raw material metal powder is 'a', where 'a' is greater than zero. Preferably, the software slice layer thickness is between 20 and 70 μm, and the particle size of the raw material metal powder is between 15 and 53 μm.

[0021] As a further explanation of the present invention, the metal powder is sieved to obtain powder with a particle size range of a to b, wherein both a and b are greater than zero, and the layer thickness c is approximately equal to (a+b) / 2.

[0022] As a further explanation of the present invention, in step 5, the drying process includes: evacuating the raw material metal powder in a drying oven, heating and holding it at that temperature, and then cooling it to room temperature; wherein, the heating temperature t = 200 ℃, the holding time T = 6 h, and the cooling method is furnace cooling.

[0023] As a further explanation of the present invention, in step 6, the substrate material and the metal material used in the printing process are preferably the same material. When the substrate material and the printing material are not the same material, materials with similar composition should be selected as the substrate material as much as possible.

[0024] As a further explanation of the present invention, when the substrate material and the printing material are not the same, the excised portion includes the part where the microstructure of the material at the junction of the substrate and the obtained metal material differs from that of other areas. Preferably, the excised portion should be approximately 2 to 5 times the layer thickness height above the substrate plane.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] 1. This invention can avoid the occurrence of protrusions and reduce stress concentration and stress release phenomena. This not only effectively reduces the defect content in the material, but also significantly expands the processing window for additive manufacturing of metallic materials.

[0027] 2. This invention also has significant advantages in high-throughput fabrication. Traditional additive manufacturing technologies often suffer from parameter suitability issues during batch fabrication. If a parameter is unsuitable, the entire batch may need to be discarded, resulting in significant economic and time costs. In contrast, the method in this study provides a wider process window, making it easier to achieve success in fabricating materials with different parameters and avoiding the waste of entire batches of material.

[0028] 3. This invention can not only improve the quality and reliability of materials, but also shorten the research and development cycle of new materials, improve production efficiency, and reduce the cost of material preparation. Attached Figure Description

[0029] Figure 1 This is a cross-sectional view of the material printed by the additive manufacturing method used in this invention to suppress cracking during the forming process of metal components.

[0030] Figure 2 is a diagram of the powder erosion mechanism in the outer protection zone.

[0031] Figure 3 is a front view of the powder ablation mechanism on the outer side of the forming area during laser processing when no protective measures are used.

[0032] Figure 4 is a top view of the powder ablation mechanism on the outer side of the forming area during laser processing when no protective measures are used.

[0033] Figure 5 This is a front view of the molten pool formed by laser melting of powder during laser operation, without the use of protective measures.

[0034] Figure 6 This is a top-view metallographic image of the molten pool formed by laser melting of powder during laser operation, without the use of protective measures.

[0035] Figure 7 is a cross-sectional SEM image of the block forming without protective measures.

[0036] Figure 8 is a cross-sectional SEM image of the block after protective measures have been taken. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Unless otherwise specified, the materials, tools, and equipment used in the embodiments of this invention are all commercially obtained.

[0039] The embodiments of the present invention use metal powder with a particle size conforming to a normal distribution, and the particle size range is 15-53 μm.

[0040] In this embodiment of the invention, the metal material is manufactured using selective laser melting (SLM) with a BLT-S210 device.

[0041] Combination Figure 1 This invention provides an additive manufacturing method for suppressing cracking during the forming process of metal components, comprising the following steps:

[0042] Step 1: Design the metal material structural component model using the 3D modeling software Magic, and set the manufacturing process parameters for the metal material structural component model. The scanning power is 200W, the scanning spacing is 90μm, the scanning speed is 180mm / s, the powder layer thickness is 55μm, a 90° rotation scanning strategy is adopted, the substrate is preheated to 200℃, and the heating source is 100μm from the corner diameter.

[0043] Step 2: Add a shell-shaped region around the modeling area as a protected area, such as... Figure 1 As shown, the manufacturing process parameters for the outer protection zone are set, and its energy density should be less than or equal to the parameters of the internal model. The scanning spacing is 120μm, the laser power is 90W, the scanning speed is 600mm / s, the powder layer thickness is 55μm, a 67° rotation scanning strategy is adopted, the substrate is preheated to 200℃, and the heating source is 100μm away from the corner diameter.

[0044] Step 3: Perform a processability test on the model, and then perform slicing and layering operations.

[0045] Step 4: Screen the metal powder raw materials to obtain spherical powder with an appropriate particle size, the maximum particle size of which does not exceed approximately twice the corresponding layer thickness. Then, place it in a drying device to eliminate the influence of impurities such as water molecules in the air on the printing process. Pre-alloyed powder with a particle size range of 15~53μm and a normal distribution is obtained through methods such as sieving. The powder is then dried at 200℃ for 6 hours.

[0046] Step 5: Select a metal substrate with a thickness of at least 17mm, and ensure that the substrate composition is similar to or the same as the printing material composition. Then, fix it on the additive manufacturing printing platform. Next, load the dried metal powder into the powder supply chamber of the equipment, install the doctor blade, and purge the forming chamber with argon gas to reduce the oxygen content to below 50ppm before starting printing.

[0047] During laser forming, under the influence of powder composition and internal pressure difference within the forming chamber, the powder surrounding the laser forming molten pool participates in the forming process, such as... Figure 2 and Figure 3 As shown in the diagram. This will cause a bulge at the end of the molten pool after laser melting, as illustrated in the diagram below. Figure 4 As shown, the protrusion phenomenon in actual material forming is as follows: Figure 5 As shown, this raised area originates from the phenomenon of edge powder being drawn in during the laser melting process.

[0048] During the printing process, the laser will first print the outer protected area, and then print the internal structural parts, such as... Figure 6 As shown. The powder surrounding the structural components participates in the molding of the outer shell area.

[0049] Without external protection, powder from the outer areas of the structural components will participate in the forming of the metal material, ultimately causing edge protrusions, such as... Figure 7 As shown. However, by using the method provided by this invention, under the condition that other process parameters are completely identical, the edges of the final formed metal material will no longer have protrusions, and the crack content will also be significantly reduced, such as... Figure 8 As shown.

[0050] Step 6: After printing is complete, remove the substrate and use processing equipment to cut off the substrate and the shell-shaped protection zone to obtain the metal material.

[0051] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An additive manufacturing method for suppressing cracking during the forming process of metal components, characterized in that, The method includes the following steps: Step 1: Use 3D modeling software to design the metal material structural component model and add the necessary support design; Step 2: Set the manufacturing process parameters for the metal material structural component model and the support model, and slice the model layer by layer according to the designed layer thickness; The energy density range of the metal material structural component model is 10–1000 J / mm². 3 ; Step 3: Add a shell-shaped area around the structural component model area as a protection zone. The width of the protection zone around the structural component model shall not be less than 2mm, and the height shall be consistent with the height of the internal structural component model. Step 4: Set the manufacturing process parameters for the outer protection zone, and ensure that the energy density input of the outer protection zone is less than or equal to that of the internal structural component model area; Step 5: Sieve out the metal powder of the corresponding layer thickness and dry it; Step 6: Using additive manufacturing process, powder is 3D printed on the substrate plane using an external heat source. During the printing process, the outer area of ​​the material is printed first, followed by the inner area, and finally a metal material structure with no or few cracks is obtained.

2. The additive manufacturing method for suppressing cracking during the forming process of metal components as described in claim 1, characterized in that, The metallic material includes at least one of intermetallic compound materials and titanium metal materials.

3. The additive manufacturing method for suppressing cracking during the forming process of metal components as described in claim 1, characterized in that, The heat source for additive manufacturing includes one of a laser heat source, a plasma heat source, or an electron beam heat source, and the additive manufacturing process includes one of selective laser melting, laser delamination melting, electron beam melting, or direct laser deposition.

4. The additive manufacturing method for suppressing cracking during the forming process of metal components as described in claim 1, characterized in that, In step 2, the process parameters include laser or electron beam focusing diameter, substrate heating temperature, processing power, scanning rate, scanning strategy, scanning spacing, and powder layer thickness; wherein, the laser or electron beam focusing diameter is 60–500 μm; the substrate heating temperature is 100–300 °C; the heating power is 50–500 W; the scanning rate is 10–1000 mm / s; the scanning strategy is unidirectional scanning strategy, unidirectional rotating alternating scanning strategy, reciprocating scanning strategy, reciprocating rotating alternating strategy, checkerboard scanning strategy, and 67° rotating scanning; the scanning spacing is 50–200 μm; and the powder layer thickness is 20–250 μm.

5. The additive manufacturing method for suppressing cracking during the forming process of metal components as described in claim 1, characterized in that, In step 5, the particle size distribution of the raw material metal powder used in the metal material structural component conforms to a normal distribution, and its average particle size corresponds to the thickness of the software slice layer of the material.

6. The additive manufacturing method for suppressing cracking during the forming process of metal components as described in claim 5, characterized in that, The thickness of the software slice layer is between 20 and 70 μm, and the particle size of the raw material metal powder is between 15 and 53 μm.

7. The additive manufacturing method for suppressing cracking during the forming process of metal components as described in claim 1, characterized in that, In step 5, the drying process includes: evacuating the raw material metal powder in a drying oven, heating and holding it at that temperature, and then cooling it to room temperature; wherein the heating temperature t = 200 ℃, the holding time T = 6 h, and the cooling method is furnace cooling.

8. The additive manufacturing method for suppressing cracking during the forming process of metal components as described in claim 1, characterized in that, In step 6, the substrate material and the metal material used in the printing process are the same material or have similar composition; When the substrate material and the printing material are not the same, the cut-off portion includes the part where the microstructure of the substrate and the resulting metal material connection is different from that of other areas.

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