A high-temperature titanium alloy small-layer-thickness short-path remelting laser selective melting additive process

Abstract

This invention relates to a short-path remelting laser selective melting additive manufacturing process for high-temperature titanium alloys with small layer thicknesses, belonging to the field of laser additive manufacturing technology. Addressing the challenge of cracking in laser selective melting of high-temperature titanium alloys, this invention innovatively proposes a short-path remelting laser selective melting additive manufacturing process with small layer thicknesses. It overcomes the challenges of temperature and stress field control during the laser selective melting process of high-temperature titanium alloys, achieving precise control of the temperature gradient and residual stress, effectively eliminating the risk of cracking during additive manufacturing. The high-temperature titanium alloy formed by this process has a density ≥99.0%, is free of cracks and incomplete fusion defects, and has a yield strength ≥1000MPa and tensile strength ≥1100MPa in the deposited state. After heat treatment, the room temperature yield strength of the titanium alloy is ≥930MPa, the tensile strength is ≥1000MPa, and the elongation is ≥10%. This solves the technical problem of cracking in additive forming of high-temperature titanium alloy components with a thickness ratio ≥5, enabling the development of products exceeding 500mm in diameter. This process has promising application prospects in aerospace and other fields.

Description

Technical Field

[0001] This invention relates to a high-temperature titanium alloy thin-layer short-path remelting laser selective melting additive manufacturing process, belonging to the field of metal additive manufacturing technology. Background Technology

[0002] High-temperature titanium alloys are a class of titanium alloys with service temperatures exceeding 600℃. These alloys possess good specific strength, specific stiffness, high-temperature performance, welding and hot / cold working properties, and are widely used as one of the key materials for complex aerospace structures.

[0003] Selective laser melting (SLM) technology, with its advantages of high precision and ability to form highly complex structures, has become the primary forming technology for complex high-temperature structural components in the aerospace field. The fabrication of high-temperature titanium alloys using SLM technology has become one of the cutting-edge research topics in the aerospace industry. However, due to the extremely high cooling rate (up to 10⁻⁶) during the SLM forming process... 6 ~10 8 High-temperature titanium alloys (TTI) are highly susceptible to martensitic transformation during additive forming (SLM). This tangential transformation generates high residual stress within the material. Furthermore, high-temperature titanium alloys contain a high content of the α phase, which has a close-packed hexagonal structure with few slip systems and poor deformability. Under the combined effects of high stress and low deformability, cracking is a severe problem in SLM high-temperature titanium alloys. To date, there are few reports on processes that can achieve additive forming of high-temperature titanium alloys.

[0004] Currently, there are two main approaches to solving the problem of cracking during SLM forming of high-temperature titanium alloys: (1) composition control and (2) SLM process optimization. It should be noted that the excellent high-temperature performance of high-temperature titanium alloys is positively correlated with the proportion of the α phase. Excessive reduction of the α content will inevitably damage the high-temperature performance of high-temperature titanium alloys. Moreover, the composition process is complex, and the interaction mechanism between elements is still unclear, resulting in high cost and minimal effect of composition control. Therefore, large-scale composition optimization based on SLM high-temperature titanium alloys is not one of the most feasible solutions to the problem of cracking during SLM forming. Process optimization can precisely control the temperature field and stress field during SLM forming by controlling process parameters, reducing the cooling gradient of the molten pool, and achieving low-stress, defect-free forming. Among them, remelting is one of the important means to control the solidification of the molten pool and regulate the cooling rate of the molten pool. However, the main reason why the previous remelting process could not form high-temperature titanium alloys is that the remelting path is too long and the remelting interval is too long, which makes it impossible to maintain a high temperature field and a low cooling rate around the molten pool, resulting in an insignificant effect on reducing internal stress. Short-path remelting, due to its short interval and slow temperature field cooling rate, can effectively reduce the internal stress of the component. Furthermore, layer thickness is also a crucial factor influencing the solidification temperature field of the molten pool. A thicker layer requires higher input energy for powder melting, resulting in a greater temperature gradient and higher stress in the molten pool. For high-temperature titanium alloys, which are difficult to produce as additive materials, a thinner layer thickness is more conducive to suppressing crack formation. Simultaneously, optimizing the short-path remelting process with small layer thickness offers advantages such as relatively simple operation and suitability for engineering applications. Therefore, SLM process optimization has become one of the optimal approaches to address cracking during SLM forming of high-temperature titanium alloys.

[0005] In the prior art, there are relatively few reports on SLM additive manufacturing processes for high-temperature titanium alloys. For example, Chinese patent CN202410492325.X reports a preparation process for additive manufacturing of 600℃ high-temperature titanium alloys; Chinese patent CN202410845186.4 reports a two-step additive manufacturing method for Ti65 high-temperature titanium alloy parts. However, the above processes are not very effective when directly applied to SLM forming of high-temperature titanium alloys, mainly due to the following reasons:

[0006] 1) The SLM additive manufacturing process reported in patent CN202410492325.X can only achieve the forming of titanium alloys at high temperatures of 600℃. However, it is not applicable to the SLM forming of Ti65 titanium alloy (650℃), Ti70 titanium alloy (700℃), and titanium-based composite materials. Although it can produce defect-free and small-sized Ti60 samples, it still cannot achieve the development of large-sized components;

[0007] 2) The SLM+hot isostatic pressing process used in patent CN202410845186.4 to form high-temperature titanium alloys is inefficient, has a long cycle, and cannot produce complex structural parts.

[0008] With the increasing operating temperatures and more complex and severe stresses experienced by next-generation aerospace structural components, the performance requirements for materials are becoming more stringent. High-temperature titanium alloys capable of SLM additive manufacturing have become one of the most favored structural materials in the aerospace field. Therefore, in order to achieve defect-free additive manufacturing of complex high-temperature titanium alloys and reduce the risk of product cracking, it is urgent to design a short-path remelting laser selective melting additive manufacturing process for high-temperature titanium alloys with small layer thickness. Summary of the Invention

[0009] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a high-temperature titanium alloy thin-layer short-path remelting laser selective melting additive manufacturing process, which effectively eliminates the risk of cracking during additive manufacturing.

[0010] The technical solution of this invention is:

[0011] This invention discloses a high-temperature titanium alloy thin-layer short-path remelting laser selective melting additive manufacturing process, comprising:

[0012] Preparation of high-temperature titanium alloy powder;

[0013] The high-temperature titanium alloy powder was placed in an oven and dried to obtain pretreated powder.

[0014] Based on the model of the part to be manufactured, a three-dimensional model of the additive structure is established;

[0015] The three-dimensional model of the additive structure is sliced ​​in two dimensions with small layer thickness to obtain the sliced ​​model.

[0016] The sliced ​​model is then imported into a laser selective melting and shaping device.

[0017] The process parameters for the selective laser melting forming process are set, the pretreated powder is used as the additive material, selective laser melting additive manufacturing is performed, and a short-path remelting process is adopted to obtain high-temperature titanium alloy parts.

[0018] The high-temperature titanium alloy parts are subjected to stress-relief annealing, wire cutting, and support removal post-processing in sequence.

[0019] The unsupported parts were subjected to X-ray and fluorescence detection to screen out qualified parts.

[0020] Furthermore, in the above process, the preparation of high-temperature titanium alloy powder includes Ti60, Ti65 or Ti70 high-temperature titanium alloys and TiB-reinforced Ti70 composite materials.

[0021] Furthermore, in the above process, the method for preparing high-temperature titanium alloy powder adopts argon gas atomization or plasma rotating electrode atomization.

[0022] Furthermore, in the above process, the step of placing the high-temperature titanium alloy powder in an oven for drying specifically involves heating the oven to 80-120°C and holding it at that temperature for 3-5 hours. During the drying process, inert gas is continuously introduced into the oven to remove the oxygen and nitrogen elements adsorbed on the surface of the high-temperature titanium alloy powder.

[0023] Furthermore, in the above process, the parameters of the pretreated powder are as follows:

[0024] Particle size distribution ranges from 15 to 53 μm; loose packing density ≥ 2.4 g / cm³ 3 Tap density ≥ 2.8 g / cm³ 3 ;

[0025] Hall flow rate ≤20s / 50g; oxygen content ≤1000ppm; nitrogen content ≤100ppm.

[0026] Furthermore, in the above process, the inert gas is argon, and the purity of the argon is greater than or equal to 99.99%.

[0027] According to claim 2, the high-temperature titanium alloy thin-layer short-path remelting laser selective melting additive manufacturing process is characterized in that, after the high-temperature titanium alloy powder is dried and kept at a constant temperature, the inert gas is stopped after the oven temperature drops below 50°C, and the high-temperature titanium alloy powder is taken out of the oven.

[0028] Furthermore, in the above process, the thickness of the sliced ​​model is 30–50 μm.

[0029] Furthermore, in the above process, the process parameters of the selective laser melting forming process are as follows: the substrate preset temperature is 100-150℃; the laser power is 200-300W; the powder layer thickness is 30μm-50μm; the scanning rate is 600mm / s-1000mm / s; the scanning spacing is 80μm-120μm; and the rotation angle is 67°.

[0030] Furthermore, in the above process, the short-path remelting process specifically includes: a single laser path length ≤ 5 mm; 2-3 remelting cycles; and a single laser path length range of 2-3 mm.

[0031] Furthermore, in the above process, during the selective laser melting and forming process, the chamber of the selective laser melting and forming equipment is filled with an inert gas, and the oxygen content in the chamber is less than 1000 ppm.

[0032] Furthermore, in the above process, stress-relief annealing is performed in a vacuum environment, with an annealing temperature range of 500–550°C and a holding time of 2–3 hours.

[0033] Furthermore, in the above process, the part body should not be damaged when removing the support; after the support is removed, surface treatment is carried out by grinding or sandblasting, depending on the characteristics of the part.

[0034] The advantages of this invention compared to existing technologies are as follows: This invention proposes a short-path remelting laser selective melting (SLM) additive manufacturing process for high-temperature titanium alloys with small layer thicknesses. It overcomes the challenges of temperature and stress field control during the SLM high-temperature titanium alloy additive manufacturing process, achieving precise control of the temperature gradient and residual stress. This effectively eliminates the risk of cracking during additive manufacturing, enabling the forming of large-size, defect-free SLM high-temperature titanium alloys and their components. Its advantages are mainly reflected in the following aspects:

[0035] (1) After additive forming using this process, the high-temperature titanium alloy achieves a density of over 99.0%, free from defects such as cracks and lack of fusion. Its yield strength in the deposited state is ≥1000 MPa, and its tensile strength is ≥1100 MPa. After heat treatment, the titanium alloy exhibits a room temperature yield strength ≥930 MPa, a tensile strength ≥1000 MPa, and an elongation ≥15%; at 700℃, its yield strength is ≥330 MPa, its tensile strength ≥500 MPa, and its elongation ≥20%.

[0036] (2) Although the short-path remelting process with small layer thickness proposed in this invention increases the printing time due to the increased number of laser remelting cycles and the smaller powder layer thickness, it can be achieved simply by controlling the process parameters. It does not increase or change the additive manufacturing process or procedures, and is characterized by its simple operation and suitability for engineering applications. At the same time, this process significantly improves the cracking tendency of SLM-high temperature titanium alloy components and increases the component qualification rate.

[0037] (3) This invention discovered the crucial role of short-path remelting with small layer thickness in SLM forming of high-temperature titanium alloys: with large layer thickness, the higher input energy density leads to a larger and deeper molten pool, a larger temperature gradient, and an increased risk of cracking; with long paths, the heat of the powder bed is severely reduced, and the effect of remelting in reducing the temperature gradient is diminished. A process window based on short-path remelting with small layer thickness for high-temperature titanium alloys is proposed: precisely controlling the temperature and stress fields during the selective laser melting of high-temperature titanium alloys in additive manufacturing effectively eliminates the risk of cracking during additive manufacturing.

[0038] (4) This invention is applicable to laser selective melting additive manufacturing of high-temperature titanium alloys such as Ti60, Ti65, and Ti70 and titanium-based composite materials. It has enabled the development of products with a thickness of over 500mm and solved the technical problem of cracking in additive manufacturing of high-temperature titanium alloy components with a thickness ratio of ≥5. It has good application prospects in high-performance complex components in aerospace and other fields. Attached Figure Description

[0039] Figure 1 This is a process route diagram of the present invention;

[0040] Figure 2 These are microstructure characterization and thin-wall structure forming effect diagrams of the Ti65 titanium alloy prepared by this invention;

[0041] Figure 3 Characterization of the microstructure of the Ti70 titanium alloy prepared in this invention;

[0042] Figure 4 The image shows the microstructure of the TiB2-reinforced Ti70 composite material prepared in this invention, with the arrow pointing to TiB2. Detailed Implementation

[0043] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] like Figure 1 As shown in the figure, this embodiment provides a high-temperature titanium alloy thin-layer short-path remelting laser selective melting additive manufacturing process, which includes the following steps:

[0045] (1) Powder pretreatment: High-temperature titanium alloy powder, either plasma rotating electrode or argon vacuum atomized, is selected as the raw material. Before additive forming, the high-temperature titanium alloy powder is placed in an oven for drying, heated to 80-120℃, and held for 3-5 hours. During the drying process, argon or other inert protective gases are continuously passed through the oven to remove as much oxygen, nitrogen, and other elements adsorbed on the powder surface as possible.

[0046] (2) Thin-layer slicing: An additive structure model is established based on the part model, and then a two-dimensional thin-layer slicing process is performed on the three-dimensional additive structure model. The sliced ​​data is then imported into a selected area laser melting forming device;

[0047] (3) Thin-layer short-path remelting additive manufacturing: Set the process parameters for the selective laser melting forming process and perform selective laser melting additive manufacturing;

[0048] (4) Additive post-processing: The processed parts are subjected to stress-relief annealing, wire cutting and support removal in sequence. After the support is removed, the parts are subjected to X-ray and fluorescence detection to finally obtain high-temperature titanium alloy parts.

[0049] The high-temperature titanium alloy powder to be prepared includes high-temperature titanium alloys such as Ti60, Ti65, and Ti70, as well as TiB-reinforced Ti70 composite materials.

[0050] The method for preparing high-temperature titanium alloy powder in step 1.1 is selected from either argon gas atomization or plasma rotating electrode atomization.

[0051] In step 1.1, the high-temperature titanium alloy powder has a particle size distribution range of 15-53 μm and a loose packing density ≥2.4 g / cm³. 3 Tap density ≥ 2.8 g / cm³3 Flowability (Hall flow rate) ≤20s / 50g, oxygen content ≤1000ppm, nitrogen content ≤100ppm.

[0052] After the high-temperature titanium alloy drying and heat preservation results in step 1.1, the argon gas supply can only be stopped when the oven temperature is below 50℃, and the oven can be opened to remove the powder.

[0053] The argon gas used in the drying process in step 1.1 has a purity of not less than 99.99%.

[0054] The slicing software selected in step 1.2 is either Magic software or another slicing software.

[0055] In step 1.2, the thickness of the small layer refers to the thickness of the powder, which is usually in the range of 30-50 μm and cannot exceed 50 μm.

[0056] The process parameters described in step 1.3 are as follows: substrate preset temperature is 100-150℃, laser power is 200-300W, powder layer thickness is 30μm-50μm, scanning rate is 600mm / s-1000mm / s, scanning spacing is 80μm-120μm, and rotation angle is 67°.

[0057] The short-path remelting mentioned in step 1.3 refers to a laser single-path length ≤ 5mm, with an optimal length of 2-3mm, and 2-3 remelting cycles.

[0058] The molding process described in step 1.3 is carried out in a cavity; the cavity contains an inert gas; and the oxygen content in the cavity is less than 1000 ppm.

[0059] After printing is completed in step 1.3, the part can only be opened and removed after the temperature inside the forming cavity is below 50°C.

[0060] Stress relief treatment in step 1.4: annealing temperature is 500-550℃, holding time is 2-3 hours, vacuum environment.

[0061] In step 1.4, the part body must not be damaged when removing the supports. After removing the supports, surface treatment methods such as grinding or sandblasting can be used depending on the characteristics of the part.

[0062] The results are as follows Figures 2-4 As shown.

[0063] Example 1 (Ti65 short-path remelting process with small layer thickness):

[0064] Example 1 utilizes a short-path remelting laser selective melting additive manufacturing process for high-temperature titanium alloys with small layer thicknesses, as proposed in this invention, to prepare Ti65 high-temperature titanium alloy and its components. The Ti65 high-temperature titanium alloy powder was prepared by argon gas atomization, with a D10 of 15–20 μm, D50 of 30–35 μm, D90 of 50–55 μm, a flowability (Hall flow rate) ≤20 s / 50 g, and a loose packing density ≥2.8 g / cm³. 3 .

[0065] S1 Powder Pretreatment: First, the required Ti65 high-temperature titanium alloy powder is subjected to low-temperature drying treatment (inert gas, 120℃, 4h) to improve powder flowability. The treated powder raw material is then loaded into the SLM equipment, TC4 titanium alloy is selected as the molding substrate, the SLM equipment is debugged, and the equipment preparation before SLM printing is completed.

[0066] S2 small layer thickness slicing: Select a powder layer thickness of 30μm, slice the high-temperature titanium alloy component, and import the sliced ​​data into the selected area laser melting forming equipment to complete the preparation of the additive model;

[0067] S3 short-path remelting additive manufacturing with small layer thickness: In an inert gas environment, the substrate of the SLM equipment is preheated to 150°C. Ti65 powder is spread on the preheated substrate, and the powder is selectively melted according to the slice model of each layer. The powder spreading and melting processes are repeated on the surface of the melted powder layer until printing is completed.

[0068] S4 additive manufacturing post-processing: Excess metal powder in high-temperature titanium alloy components is removed using a powder removal device; then, stress-relief annealing, wire cutting, support removal, and non-destructive testing are performed on the structural components to obtain high-temperature titanium alloy components.

[0069] The SLM process parameters in step S3 are as follows: substrate preset temperature is 100-150℃, laser power is 200W, powder layer thickness is 30μm, scanning rate is 1000mm / s, scanning spacing is 80μm, rotation angle is 67°, path length is 3mm, and remelting is performed twice.

[0070] The stress-relief annealing process parameters in step S4 are: vacuum environment, 500-550℃, 2-3h, and cooling.

[0071] Example 2 (Ti70 small layer thickness short path remelting process):

[0072] Example 1 utilizes a short-path remelting laser selective melting additive manufacturing process for high-temperature titanium alloys with small layer thicknesses, as proposed in this invention, to prepare Ti70 high-temperature titanium alloy and its components. The Ti70 high-temperature titanium alloy powder was prepared by argon gas atomization, with a D10 of 15–20 μm, D50 of 30–35 μm, D90 of 50–55 μm, a flowability (Hall flow rate) ≤20 s / 50 g, and a loose packing density ≥2.8 g / cm³. 3 .

[0073] S1 Powder Pretreatment: First, the required Ti70 high-temperature titanium alloy powder is subjected to low-temperature drying treatment (inert gas, 120℃, 4h) to improve powder flowability. The treated powder raw material is then loaded into the SLM equipment, TC4 titanium alloy is selected as the molding substrate, the SLM equipment is debugged, and the equipment preparation before SLM printing is completed.

[0074] S2 small layer thickness slicing: Select a powder layer thickness of 30μm, slice the high-temperature titanium alloy component, and import the sliced ​​data into the selected area laser melting forming equipment to complete the preparation of the additive model;

[0075] S3 short-path remelting additive manufacturing with small layer thickness: In an inert gas environment, the substrate of the SLM equipment is preheated to 150°C. Ti70 powder is spread on the preheated substrate, and the powder is selectively melted according to the slice model of each layer. The powder spreading and melting processes are repeated on the surface of the melted powder layer until printing is completed.

[0076] S4 additive manufacturing post-processing: Excess metal powder in high-temperature titanium alloy components is removed using a powder removal device; then, stress-relief annealing, wire cutting, support removal, and non-destructive testing are performed on the structural components to obtain high-temperature titanium alloy components.

[0077] In step S3, the SLM process parameters are as follows: substrate preset temperature is 100-150℃, laser power is 250W, powder layer thickness is 30μm, scanning rate is 800mm / s, scanning spacing is 80μm, rotation angle is 67°, path length is 3mm, and remelting is performed 3 times.

[0078] The stress-relief annealing process parameters in step S4 are: vacuum environment, 500-550℃, 2-3h, and cooling.

[0079] Example 3 (Short-path remelting process for small-layer-thickness Ti70 composite material reinforced with TiB2):

[0080] Example 1 utilizes a high-temperature titanium alloy thin-layer short-path remelting laser selective melting additive manufacturing process proposed in this invention to prepare TiB2-reinforced Ti70 composite materials and their components. The TiB2-reinforced Ti70 composite powder was prepared by argon gas atomization, with a D10 of 15–20 μm, D50 of 30–35 μm, D90 of 50–55 μm, flowability (Hall flow rate) ≤20 s / 50 g, and loose packing density ≥2.8 g / cm³. 3 .

[0081] S1 Powder Pretreatment: First, the required TiB2-reinforced Ti70 composite powder is subjected to low-temperature drying treatment (inert gas, 120℃, 4h) to improve powder flowability. The treated powder raw material is then loaded into the SLM equipment, TC4 titanium alloy is selected as the molding substrate, the SLM equipment is debugged, and the equipment preparation before SLM printing is completed.

[0082] S2 small layer thickness slicing: Select a powder layer thickness of 30μm, slice the high-temperature titanium alloy component, and import the sliced ​​data into the selected area laser melting forming equipment to complete the preparation of the additive model;

[0083] S3 Small Layer Thickness Short Path Remelting Additive Manufacturing: In an inert gas environment, the substrate of the SLM equipment is preheated to 150°C. TiB2-reinforced Ti70 composite powder is spread on the preheated substrate, and the powder is selectively melted according to the slice model of each layer. The powder spreading and melting processes are repeated on the surface of the melted powder layer until printing is completed.

[0084] S4 additive manufacturing post-processing: Excess metal powder in high-temperature titanium alloy components is removed using a powder removal device; then, stress-relief annealing, wire cutting, support removal, and non-destructive testing are performed on the structural components to obtain high-temperature titanium alloy components.

[0085] In step S3, the SLM process parameters are as follows: substrate preset temperature is 100-150℃, laser power is 300W, powder layer thickness is 30μm, scanning rate is 600mm / s, scanning spacing is 80μm, rotation angle is 67°, path length is 2mm, and remelting is performed 3 times.

[0086] The stress-relief annealing process parameters in step S4 are: vacuum environment, 500-550℃, 2-3h, and cooling.

[0087] Comparative Example 1 (Ti65 titanium alloy thick layer short path remelting process):

[0088] Comparative Example 1 utilizes this invention to propose a short-path remelting laser selective melting additive manufacturing process for high-temperature titanium alloys with large layer thicknesses, to prepare Ti65 high-temperature titanium alloy and its components. The Ti65 high-temperature titanium alloy powder is prepared by argon gas atomization, with a D10 of 15–20 μm, D50 of 30–35 μm, D90 of 50–55 μm, a flowability (Hall flow rate) ≤20 s / 50 g, and a loose packing density ≥2.8 g / cm³. 3 .

[0089] S1 Powder Pretreatment: First, the required Ti65 high-temperature titanium alloy powder is subjected to low-temperature drying treatment (inert gas, 120℃, 4h) to improve powder flowability. The treated powder raw material is then loaded into the SLM equipment, TC4 titanium alloy is selected as the molding substrate, the SLM equipment is debugged, and the equipment preparation before SLM printing is completed.

[0090] S2 small layer thickness slicing: Select a powder layer thickness of 60μm, slice the high-temperature titanium alloy component, and import the sliced ​​data into the selected area laser melting forming equipment to complete the preparation of the additive model;

[0091] S3 short-path remelting additive manufacturing with small layer thickness: In an inert gas environment, the substrate of the SLM equipment is preheated to 150°C. Ti65 powder is spread on the preheated substrate, and the powder is selectively melted according to the slice model of each layer. The powder spreading and melting processes are repeated on the surface of the melted powder layer until printing is completed.

[0092] S4 additive manufacturing post-processing: Excess metal powder in high-temperature titanium alloy components is removed using a powder removal device; then, stress-relief annealing, wire cutting, support removal, and non-destructive testing are performed on the structural components to obtain high-temperature titanium alloy components.

[0093] The SLM process parameters in step S3 are as follows: substrate preset temperature is 100-150℃, laser power is 200W, powder layer thickness is 60μm, scanning rate is 1000mm / s, scanning spacing is 80μm, rotation angle is 67°, path length is 3mm, and remelting is performed twice.

[0094] The stress-relief annealing process parameters in step S4 are: vacuum environment, 500-550℃, 2-3h, and cooling.

[0095] Comparative Example 2 (Ti65 titanium alloy thin-layer long-path remelting process):

[0096] Comparative Example 2 utilizes this invention to propose a high-temperature titanium alloy, Ti65, and its components using a thin-layer, long-path remelting laser selective melting additive manufacturing process. The Ti65 high-temperature titanium alloy powder is prepared by argon gas atomization, with a D10 of 15–20 μm, D50 of 30–35 μm, D90 of 50–55 μm, a flowability (Hall flow rate) ≤20 s / 50 g, and a loose packing density ≥2.8 g / cm³. 3 .

[0097] S1 Powder Pretreatment: First, the required Ti65 high-temperature titanium alloy powder is subjected to low-temperature drying treatment (inert gas, 120℃, 4h) to improve powder flowability. The treated powder raw material is then loaded into the SLM equipment, TC4 titanium alloy is selected as the molding substrate, the SLM equipment is debugged, and the equipment preparation before SLM printing is completed.

[0098] S2 small layer thickness slicing: Select a powder layer thickness of 60μm, slice the high-temperature titanium alloy component, and import the sliced ​​data into the selected area laser melting forming equipment to complete the preparation of the additive model;

[0099] S3 short-path remelting additive manufacturing with small layer thickness: In an inert gas environment, the substrate of the SLM equipment is preheated to 150°C. Ti65 powder is spread on the preheated substrate, and the powder is selectively melted according to the slice model of each layer. The powder spreading and melting processes are repeated on the surface of the melted powder layer until printing is completed.

[0100] S4 additive manufacturing post-processing: Excess metal powder in high-temperature titanium alloy components is removed using a powder removal device; then, stress-relief annealing, wire cutting, support removal, and non-destructive testing are performed on the structural components to obtain high-temperature titanium alloy components.

[0101] The SLM process parameters in step S3 are as follows: substrate preset temperature is 100-150℃, laser power is 200W, powder layer thickness is 30μm, scanning rate is 1000mm / s, scanning spacing is 80μm, rotation angle is 67°, path length is 10mm, and remelting is performed twice.

[0102] The stress-relief annealing process parameters in step S4 are: vacuum environment, 500-550℃, 2-3h, and cooling.

[0103] Comparative Example 3 (Ti65 titanium alloy small layer thickness long path single melting process):

[0104] Comparative Example 3 utilizes this invention to propose a high-temperature titanium alloy and its components using a single-path laser selective melting additive manufacturing process with small layer thickness and long path. The Ti65 high-temperature titanium alloy powder is prepared by argon gas atomization, with a D10 of 15–20 μm, D50 of 30–35 μm, D90 of 50–55 μm, flowability (Hall flow rate) ≤20 s / 50 g, and loose packing density ≥2.8 g / cm³. 3 .

[0105] S1 Powder Pretreatment: First, the required Ti65 high-temperature titanium alloy powder is subjected to low-temperature drying treatment (inert gas, 120℃, 4h) to improve powder flowability. The treated powder raw material is then loaded into the SLM equipment, TC4 titanium alloy is selected as the molding substrate, the SLM equipment is debugged, and the equipment preparation before SLM printing is completed.

[0106] S2 small layer thickness slicing: Select a powder layer thickness of 60μm, slice the high-temperature titanium alloy component, and import the sliced ​​data into the selected area laser melting forming equipment to complete the preparation of the additive model;

[0107] S3 short-path remelting additive manufacturing with small layer thickness: In an inert gas environment, the substrate of the SLM equipment is preheated to 150°C. Ti65 powder is spread on the preheated substrate, and the powder is selectively melted according to the slice model of each layer. The powder spreading and melting processes are repeated on the surface of the melted powder layer until printing is completed.

[0108] S4 additive manufacturing post-processing: Excess metal powder is removed from the high-temperature titanium alloy components using a powder removal device; then, the structural components undergo stress-relief annealing, wire cutting, support removal, and non-destructive testing to obtain the high-temperature titanium alloy components. For example... Figure 3 and Figure 4 As shown.

[0109] SLM process parameters in step S3: substrate preset temperature is 100-150℃, laser power is 200W, powder layer thickness is 30μm, scanning rate is 1000mm / s, scanning spacing is 80μm, rotation angle is 67°, path length is 2-3mm, and no remelting.

[0110] Table 1 Mechanical properties of the Ti65 titanium alloy formed according to the present invention in the deposited and heat-treated states.

[0111]

[0112] Table 2 Mechanical properties of the Ti70 titanium alloy formed according to the present invention in the deposited and heat-treated states.

[0113]

[0114] Table 3 Mechanical properties of the TiB2-reinforced Ti70 composite material formed according to the present invention in the deposited state and heat-treated state.

[0115]

[0116] Table 4 shows the molding effects of the embodiments and comparative examples.

[0117]

[0118] Examples 1, 2, and 3 demonstrate the effectiveness of the present invention in crack-free forming of high-temperature titanium alloys;

[0119] Example 1 and Comparative Example 1 demonstrate that a thinner powder layer helps to suppress crack formation;

[0120] Example 1 and Comparative Example 2 demonstrate that short-path remelting helps suppress crack formation.

[0121] Example 1 and Comparative Example 3 demonstrate the effect of remelting on crack suppression.

[0122] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

[0123] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A high-temperature titanium alloy thin-layer short-path remelting laser selective melting additive manufacturing process, characterized in that, include: Preparation of high-temperature titanium alloy powder; The high-temperature titanium alloy powder is placed in an oven and dried. The oven is heated to 80-120°C and kept at that temperature for 3-5 hours to obtain the pretreated powder. Based on the model of the part to be manufactured, a three-dimensional model of the additive structure is established; The three-dimensional model of the additive structure is sliced ​​in two dimensions with small layer thickness to obtain the sliced ​​model. The sliced ​​model is then imported into a laser selective melting and shaping device. The process parameters for the laser selective melting forming process are set, the pretreated powder is used as the additive material, selective laser melting additive manufacturing is performed, and a short path remelting process is adopted to obtain high temperature titanium alloy parts. The high-temperature titanium alloy parts are subjected to stress-relief annealing, wire cutting, and support removal post-processing in sequence. The unsupported parts were subjected to X-ray and fluorescence detection to screen out qualified parts; The parameters of the pretreated powder are as follows: Particle size distribution ranges from 15 to 53 μm; loose packing density ≥ 2.4 g / cm³ 3 Tap density ≥ 2.8 g / cm³ 3 ; Hall flow rate ≤20s / 50g; oxygen content ≤1000ppm; nitrogen content ≤100ppm; The specific process parameters for the selective laser melting and forming process are as follows: the substrate preset temperature is 100-150℃; the laser power is 200~300W; the powder layer thickness is 30μm~50μm; the scanning rate is 600mm / s~1000mm / s; the scanning spacing is 80μm~120μm; and the rotation angle is 67°.

2. The high-temperature titanium alloy thin-layer short-path remelting laser selective melting additive manufacturing process according to claim 1, characterized in that, The preparation of high-temperature titanium alloy powder includes Ti60, Ti65 or Ti70 high-temperature titanium alloys and TiB-reinforced Ti70 composite materials.

3. The high-temperature titanium alloy thin-layer short-path remelting laser selective melting additive manufacturing process according to claim 1, characterized in that, The method for preparing high-temperature titanium alloy powder employs argon gas atomization or plasma rotating electrode atomization.

4. The high-temperature titanium alloy thin-layer short-path remelting laser selective melting additive manufacturing process according to claim 1, characterized in that, The process of drying the high-temperature titanium alloy powder in an oven involves continuously introducing inert gas into the oven during the drying process, using the introduced inert gas to carry away the oxygen and nitrogen elements adsorbed on the surface of the high-temperature titanium alloy powder.

5. The high-temperature titanium alloy thin-layer short-path remelting laser selective melting additive manufacturing process according to claim 4, characterized in that, The inert gas is argon, and the purity of the argon is greater than or equal to 99.99%.

6. The high-temperature titanium alloy small-layer-thickness short-path remelting laser selective melting additive manufacturing process according to claim 4, characterized in that, After the high-temperature titanium alloy powder has finished drying and heat preservation, the inert gas supply is stopped when the oven temperature drops below 50°C, and the high-temperature titanium alloy powder is removed from the oven.

7. The high-temperature titanium alloy thin-layer short-path remelting laser selective melting additive manufacturing process according to claim 1, characterized in that, The thickness of the sliced ​​model is 30~50μm.

8. The high-temperature titanium alloy small-layer-thickness short-path remelting laser selective melting additive manufacturing process according to claim 1, characterized in that, The short-path remelting process specifically involves: a single laser path length ≤ 5mm; and 2-3 remelting cycles.

9. The high-temperature titanium alloy small-layer-thickness short-path remelting laser selective melting additive manufacturing process according to claim 8, characterized in that, The length of a single laser path ranges from 2 to 3 mm.

10. The high-temperature titanium alloy thin-layer short-path remelting laser selective melting additive manufacturing process according to claim 1, characterized in that, During the selective laser melting process, the chamber of the selective laser melting equipment is filled with an inert gas, and the oxygen content in the chamber is less than 1000 ppm.

11. The high-temperature titanium alloy small-layer-thickness short-path remelting laser selective melting additive manufacturing process according to claim 1, characterized in that, Stress-relief annealing is performed in a vacuum environment, with an annealing temperature range of 500~550℃ and a holding time of 2-3 hours.

12. The high-temperature titanium alloy thin-layer short-path remelting laser selective melting additive manufacturing process according to claim 1, characterized in that, The part body should not be damaged when removing the support; after removing the support, surface treatment should be carried out by grinding or sandblasting, depending on the characteristics of the part.

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