Alpha-ti alloy material for laser 3D printing and preparation method thereof

Abstract

The application provides an alpha-Ti alloy material for laser 3D printing and a preparation method thereof, and belongs to the technical field of alloy materials.The alpha-Ti alloy material contains, in mass percentage, Al 5.5-6.5%, Zr 9-13%, Si 0.2-0.4%, impurities with a total content of not more than 0.1%, and the balance of Ti; the preparation method comprises the following steps: weighing pure metal raw materials according to the mass percentage, obtaining a pre-alloy melt through suspension smelting, then performing gas atomization to prepare the alpha-Ti alloy powder material, and finally printing the alpha-Ti alloy powder material into a shaped part through a selective laser melting process to obtain the alpha-Ti alloy shaped part. The alloy material is prepared by optimizing the proportioning of Al, Zr and Si, and forms a dense and crack-free alpha single-phase structure in a printing state, has super-high strength, good plasticity and excellent high-temperature mechanical properties, and the raw material cost is significantly reduced, so that the alloy material can be used for high-temperature key structural parts in aerospace.

Description

Technical Field

[0001] This invention relates to the field of alloy materials technology, and in particular to an α-Ti alloy material for laser 3D printing and its preparation method. Background Technology

[0002] Titanium alloys are widely used in aerospace, marine engineering, and biomedical fields due to their high specific strength, excellent corrosion resistance, and good biocompatibility. Among them, near-alpha and alpha titanium alloys (such as TA7, Ti-8Al-1Mo-1V, etc.) have excellent creep resistance, weldability, and thermal stability, making them ideal candidate materials for manufacturing high-temperature structural components such as aircraft control wings, engine casings, hypersonic vehicle skins, and nose cones.

[0003] However, traditional α-type titanium alloys generally have three prominent problems: First, in order to obtain sufficient high-temperature strength and creep resistance, a high content of Al is often required, which easily leads to the precipitation of the brittle Ti3Al phase; second, existing titanium alloys usually contain expensive β-stabilizing elements such as V, Mo, and Nb, such as TC4 and Ti5553, resulting in high raw material costs; third, when the above alloys are used in additive manufacturing processes such as selective laser melting, the non-equilibrium structure and thermal stress generated by rapid solidification easily form coarse columnar crystals, element segregation, and printing cracks, which seriously reduce the mechanical properties and forming quality of the components.

[0004] Therefore, it is necessary to develop an α single-phase titanium alloy that has both low cost advantages and can adapt to the requirements of 3D printing process, as well as excellent room temperature and high temperature mechanical properties, to meet the current engineering application needs. Summary of the Invention

[0005] To overcome the shortcomings of existing 3D printed titanium alloys, such as easy cracking, poor high-temperature performance, and high cost, the present invention aims to provide an α-Ti alloy material for laser 3D printing and its preparation method. This alloy material, through optimized proportions of Al, Zr, and Si, forms a dense, crack-free α single-phase structure in the printing state, exhibiting ultra-high strength, good plasticity, and excellent high-temperature mechanical properties, while significantly reducing raw material costs.

[0006] To achieve the above objectives, the present invention provides the following solution: On one hand, the present invention provides an α-Ti alloy material for laser 3D printing, comprising, by mass percentage: Al 5.5~6.5%, Zr 9~13%, Si 0.2~0.4%, with a total impurity content not exceeding 0.1%, and the balance being Ti.

[0007] Preferably, the mass ratio of Zr to Al satisfies 0.5 ≤ Zr / Al ≤ 3.

[0008] Preferably, the α-Ti alloy material does not contain V, Mo, or Nb elements.

[0009] Preferably, the α-Ti alloy material is a spherical powder with an average particle size of 30 μm and a particle size range of 15 μm to 53 μm.

[0010] On the other hand, the present invention also provides a method for preparing the above-mentioned α-Ti alloy material, comprising the following steps: S1. Weigh pure metal raw materials according to the preset proportions and components, and obtain a pre-alloyed melt through suspension melting; S2. The pre-alloyed melt is atomized and sieved to obtain α-Ti alloy powder material; S3. The α-Ti alloy powder material is printed into shape using selective laser melting process to prepare α-Ti alloy molded parts.

[0011] Preferably, in step S2, the gas atomization is performed using helium atomization.

[0012] Preferably, in step S3, the selective laser melting process parameters are: laser scanning power 155~255W, scanning speed 800~1200mm / s, layer thickness 0.02~0.08mm, and scanning spacing 0.1~0.2mm.

[0013] Preferably, the α-Ti alloy formed part has an α single-phase structure with uniform structure, no cracks, and high density.

[0014] Preferably, the α-Ti alloy formed part has a room temperature tensile strength greater than 1.5 GPa, an elongation of not less than 10%, a specific strength of not less than 340 kN·m / kg, and a tensile strength at 600℃ greater than 900 MPa.

[0015] Preferably, the α-Ti alloy formed parts are used for aircraft rudder wing structures, engine components, hypersonic aircraft skins, or nose cones.

[0016] Compared with the prior art, the present invention discloses at least the following technical effects: This invention uses inexpensive elements such as Al, Zr, and Si to replace expensive alloying elements such as V, Mo, and Nb, reducing raw material costs by more than 20% compared to traditional Ti-6Al-4V alloys. It eliminates the need for strategically scarce metals, lowers supply chain risks, and is more suitable for large-scale industrial applications. Based on Al's solid solution strengthening, improved α-phase stability, and enhanced high-temperature creep resistance; Zr's reduction of the β→α phase transformation temperature, suppression of brittle ω-phase precipitation, and formation of beneficial atomic pairs with Al to optimize the microstructure; and Si's solid solution strengthening and the synergistic mechanism of forming Cotillard gas clusters to pin dislocations during the 3D printing thermal cycle, combined with optimized alloy proportions, the formation of brittle intermetallic compounds is effectively avoided. This fundamentally solves the problem of cracking and other defects in traditional titanium alloy laser 3D printing. The problem of low density is addressed by using a 3D printing process with optimal matching to produce parts with a uniform and stable α single-phase microstructure. These parts are crack-free and have high density, with a room temperature tensile strength exceeding 1.5 GPa, an elongation of not less than 10%, and a tensile strength exceeding 900 MPa at 600℃. This achieves an efficient match between ultra-high strength and good plasticity. At the same time, the alloy has a specific strength of up to 340 kN·m / kg. When applied to key components such as hypersonic vehicle skin, nose cone, and engine casing, it can achieve a weight reduction of 15-25%. The α single-phase microstructure also endows the material with excellent thermal stability and oxidation resistance, significantly improving thermal protection performance and extending the service life of key components. This meets the lightweight and long-term service requirements of high-temperature aerospace structural components. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of a method for preparing α-Ti alloy material for laser 3D printing according to the present invention; Figure 2 The scanning electron microscope (BSE mode) morphology image of the α-Ti pre-alloyed powder for laser 3D printing provided by the present invention has a magnification of 200×. Figure 3 The image shows a low-magnification scanning electron microscope (secondary electron SE mode) microstructure of the laser 3D printed α-Ti alloy component provided in Embodiment 1 of the present invention, with a magnification of 80×. Figure 4 This is a high-magnification scanning electron microscope (SEM) micrograph of the laser 3D printed α-Ti alloy component provided in Embodiment 1 of the present invention, with a magnification of 1000×. Figure 5The room temperature tensile engineering stress-engineering strain curve of the laser 3D printed α-Ti alloy component provided in Embodiment 1 of the present invention is shown. Figure 6 The room temperature tensile engineering stress-engineering strain curve of the laser 3D printed titanium alloy component provided in Comparative Example 5 of this invention is shown. Detailed Implementation

[0019] 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.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] like Figure 1 As shown, this invention provides a method for preparing α-Ti alloy material for laser 3D printing, comprising the following steps: S1. Weigh pure metal raw materials according to the preset proportions and components, and obtain a pre-alloyed melt through suspension melting.

[0022] Specifically, the pure metal raw material has the following mass percentage composition: Al 5.5~6.5%, Zr 9~13%, Si 0.2~0.4%, with a total impurity content of no more than 0.1%, and the balance being Ti; wherein the mass ratio of Zr to Al satisfies 0.5≤Zr / Al≤3, and no expensive alloying elements such as V, Mo, and Nb are added to the raw material. The raw material cost is reduced by more than 20% compared with the traditional Ti-6Al-4V alloy, avoiding the use of strategically scarce metals, with low supply chain risk, and is more suitable for large-scale industrial applications.

[0023] As a preferred embodiment of the present invention, the mechanism of action of each element in the α-Ti alloy is as follows: The addition of Al aims to improve the stability and phase transformation temperature of the α phase, generate a significant solid solution strengthening effect and high-temperature creep resistance, improve room temperature and medium temperature strength, and reduce the alloy density; the addition of Si aims to generate solid solution strengthening effect, and at the same time form Cotillard gas clusters to pin dislocations during 3D printing thermal cycling and high-temperature service; the addition of Zr aims to lower the β→α phase transformation temperature, suppress the precipitation of brittle ω phase, and improve the high-temperature strength and creep resistance of the alloy; the Zr / Al ratio in the Ti alloy is 0.5≤Zr / Al≤3, which aims to ensure that Al and Zr have a strong interaction and form Al-Zr atomic pairs. A reasonable Zr / Al ratio can ensure that these two elements form beneficial atomic pairs in the matrix and optimize the overall microstructure.

[0024] Using the same preparation method, if Zr / Al < 0.5, a brittle Ti3Al phase will easily form, leading to a decrease in plasticity and thermal stability; if Zr / Al > 3, the phase stability and transformation behavior begin to become more complex, leading to a decrease in high-temperature strength.

[0025] S2. The pre-alloyed melt is atomized and sieved to obtain α-Ti alloy powder material.

[0026] Specifically, helium atomization is used, where the high cooling rate of helium ensures rapid solidification of the pre-alloyed melt, forming powder particles with high sphericity and few satellite spheres. After sieving, the resulting powder has a particle size range of 15μm to 53μm, with an average particle size of 30μm. The powder exhibits excellent flowability and low oxygen content, making it suitable for the powder spreading and laser absorption requirements of selective laser melting processes, reducing porosity and incomplete fusion defects during printing. Figure 2 As shown, the prepared powder is in the form of regular spheres with a concentrated particle size distribution and no obvious agglomeration or irregular particles, which provides a raw material basis for the high density of the molded parts.

[0027] S3. The α-Ti alloy powder material is printed into shape using selective laser melting process to prepare α-Ti alloy molded parts.

[0028] Specifically, based on the optimized alloy composition design described above, combined with the selective laser melting process parameters of this invention, a crack-free and high-density forming effect can be achieved. The parameters of the selective laser melting process are: laser scanning power 155~255W, scanning speed 800~1200mm / s, layer thickness 0.02~0.08mm, and scanning spacing 0.1~0.2mm. Through the joint control of the above parameters, the powder can be fully melted and a stable molten pool can be formed, avoiding crack defects caused by thermal stress concentration, while ensuring tight interlayer bonding. After printing, the obtained α-Ti alloy forming part has an α single-phase structure, with uniform structure, no cracks, and high density. Under room temperature conditions, the tensile strength of the forming part is greater than 1.5GPa, the elongation is not less than 10%, and the specific strength is not less than 340kN·m / kg. Under high temperature conditions of 600℃, the tensile strength is greater than 900MPa, achieving an efficient match between ultra-high strength and good plasticity.

[0029] In addition, this molded part can be used in key aerospace components such as aircraft rudder structure parts, engine parts, hypersonic vehicle skin or nose cone, etc. Utilizing its excellent specific strength, thermal stability and oxidation resistance, it can achieve a weight reduction of 15~25% and extend the service life of the parts.

[0030] Example 1 This embodiment provides a method for preparing α-Ti alloy material for laser 3D printing, the specific steps of which are as follows: Step 1: Raw Material Proportioning and Melting: Prepare the alloy raw materials by mass percentage: Al: 6.0%, Zr: 12.8%, Si: 0.35%, with a total impurity content ≤0.1%, and the balance being Ti. This formula does not contain expensive strategic metal elements such as V, Mo, and Nb, and the Zr / Al mass ratio is approximately 2.13. Through the combined action of Al, Zr, and Si elements, solid solution strengthening, dislocation pinning, and inhibition of brittle phase precipitation are achieved. Weigh high-purity metal blocks according to the proportions and prepare a homogeneous pre-alloyed melt using a suspension melting process.

[0031] Step 2, Helium atomization powder making: The smelted pre-alloy melt is transferred into an atomization tank and high-speed atomization solidification is carried out using helium atomization technology. The high cooling rate of helium is used to obtain pre-alloy powder with excellent sphericity.

[0032] Step 3, Powder Sieving and Drying: The atomized powder is sieved to obtain spherical alloy powder with a particle size range of 15μm~53μm and an average particle size of 30μm; the sieved powder is placed in a drying oven for heat preservation and drying to remove moisture from the powder surface and ensure the stability of the printing process.

[0033] Step 4: Selective Laser Melting 3D Printing: The aforementioned alloy powder is used for laser 3D printing. The printing parameters are: laser power 200W, scanning speed 1200mm / s, layer thickness 0.05mm, and scanning spacing 0.1mm. After printing, the component is left to form naturally without any heat treatment.

[0034] The alloy component prepared in this embodiment has a uniform and dense microstructure, free of pores and cracks, and is a single α-phase microstructure. Figure 3 As shown, the low-magnification microstructure of the α-Ti alloy component formed by laser 3D printing in Example 1 is continuous and complete, without macroscopic cracks, pores, or incomplete fusion defects, resulting in excellent forming quality; as Figure 4 As shown, the high-magnification microstructure of the alloy component in Example 1 is a uniformly distributed needle-like α-phase structure with no brittle second phase precipitation, exhibiting excellent microstructural stability; as Figure 5 As shown, the room temperature tensile stress-strain curve of the alloy component in Example 1 is smooth without abrupt changes, exhibiting high stress peak and good tensile strain, demonstrating excellent strength-plasticity matching characteristics.

[0035] Tests showed that the component in this embodiment has a room temperature tensile strength of 1564 MPa, an elongation of 10.7%, a high temperature tensile strength of 946 MPa at 600℃, and a room temperature specific strength of 346 kN·m / kg, which fully meets the requirements of ultra-high strength, good plasticity and excellent high temperature performance.

[0036] Example 2 This embodiment provides a method for preparing α-Ti alloy material for laser 3D printing, the specific steps of which are as follows: Step 1: Raw Material Proportioning and Smelting: Prepare the alloy raw materials by mass percentage: Al: 5.8%, Zr: 13%, Si: 0.4%, total impurity content ≤0.1%, balance Ti; Zr / Al mass ratio approximately 2.24, with no V, Mo, or Nb elements added. Weigh high-purity metal blocks according to the proportions and obtain a homogeneous pre-alloyed melt through suspension smelting.

[0037] Step 2, Helium atomization powder preparation: The pre-alloy melt is atomized using a helium atomization process and rapidly solidified to prepare pre-alloy powder.

[0038] Step 3, Powder Sieving and Drying: Sieving yields spherical alloy powder with a particle size of 15μm~53μm and an average particle size of 30μm. The powder is then subjected to heat preservation and drying treatment.

[0039] Step 4: Selective Laser Melting 3D Printing: Printing process parameters are: laser power 250W, scanning speed 1200mm / s, layer thickness 0.05mm, scanning spacing 0.1mm; no heat treatment is required for the printed component.

[0040] Tests showed that the component obtained in this embodiment has a uniform α single-phase structure, is dense and crack-free; its room temperature tensile strength is 1533 MPa, its elongation is 10.8%, its 600℃ tensile strength is 912 MPa, and its room temperature specific strength is 341 kN·m / kg, demonstrating excellent comprehensive mechanical properties.

[0041] Example 3 This embodiment provides a method for preparing α-Ti alloy material for laser 3D printing, the specific steps of which are as follows: Step 1, Raw Material Proportioning and Melting: Prepare alloy raw materials by mass percentage: Al: 6.5%, Zr: 13%, Si: 0.2%, total impurity content ≤0.1%, balance Ti; Zr / Al mass ratio approximately 2.0, with no rare precious metals added. Prepare a homogeneous pre-alloyed melt by suspension melting.

[0042] Step 2, Helium atomization powder preparation: Pre-alloyed powder is prepared using a helium atomization process.

[0043] Step 3, Powder sieving and drying: Sieving yields spherical powder with a particle size of 15μm~53μm and an average particle size of 30μm, which is then dried at a warm temperature for later use.

[0044] Step 4: Selective Laser Melting 3D Printing: The printing process parameters are: laser power 200W, scanning speed 1000mm / s, layer thickness 0.05mm, and scanning spacing 0.12mm; the printed components do not require heat treatment.

[0045] Tests showed that the component obtained in this embodiment has a pure α single-phase dense structure without cracks or defects; the room temperature tensile strength is 1523 MPa, the elongation is 11.0%, the 600℃ tensile strength is 907 MPa, the room temperature specific strength is 340 kN·m / kg, the plasticity is optimal, and the strength and plasticity are well matched.

[0046] Example 4 This embodiment provides a method for preparing α-Ti alloy material for laser 3D printing, the specific steps of which are as follows: Step 1: Raw Material Proportioning and Melting: Prepare the alloy raw materials by mass percentage: Al: 5.5%, Zr: 10%, Si: 0.3%, total impurity content ≤0.1%, balance Ti; Zr / Al mass ratio approximately 1.82, free of V, Mo, and Nb elements. Prepare a homogeneous pre-alloyed melt through suspension melting.

[0047] Step 2, Helium atomization powder preparation: Pre-alloyed powder is prepared using a helium atomization process.

[0048] Step 3, Powder sieving and drying: Sieving yields spherical powder with a particle size of 15μm~53μm and an average particle size of 30μm, followed by heat preservation and drying.

[0049] Step 4: Selective Laser Melting 3D Printing: Printing process parameters are: laser power 155W, scanning speed 1000mm / s, layer thickness 0.05mm, scanning spacing 0.12mm; no heat treatment is required for the printed components.

[0050] Tests showed that the component obtained in this embodiment has a uniform and dense structure without cracks, and is an α single-phase structure; the room temperature tensile strength is 1565 MPa, the elongation is 10.0%, the 600℃ tensile strength is 950 MPa, and the room temperature specific strength is 350 kN·m / kg.

[0051] Example 5 This embodiment provides a method for preparing α-Ti alloy material for laser 3D printing, the specific steps of which are as follows: Step 1, Raw Material Proportioning and Melting: Prepare alloy raw materials by mass percentage: Al: 6.0%, Zr: 13%, Si: 0.2%, total impurity content ≤0.1%, balance Ti; Zr / Al mass ratio approximately 2.17. Prepare a homogeneous pre-alloyed melt by suspension melting.

[0052] Step 2, Helium atomization powder preparation: Pre-alloyed powder is prepared using a helium atomization process.

[0053] Step 3, Powder sieving and drying: Sieving yields spherical powder with a particle size of 15μm~53μm and an average particle size of 30μm, which is then dried at a warm temperature for later use.

[0054] Step 4: Selective Laser Melting 3D Printing: The printing process parameters are: laser power 155W, scanning speed 1000mm / s, layer thickness 0.05mm, and scanning spacing 0.12mm; the printed components do not require heat treatment.

[0055] Tests showed that the component obtained in this embodiment has a dense, crack-free α-phase structure; its room temperature tensile strength is 1530 MPa, its elongation is 10.5%, its tensile strength at 600℃ is 175 MPa, and its room temperature specific strength is 340 kN·m / kg.

[0056] To visually demonstrate the mechanical properties of the alloy components in each embodiment of the present invention, the room temperature strength, plasticity, high temperature strength and specific strength data of each embodiment are summarized in Table 1 below.

[0057] Table 1. Mechanical property data of alloys in the examples.

[0058] As shown in Table 1, all embodiments provided by this invention form a uniform and dense α-phase microstructure, free from cracks and pore defects, exhibiting excellent comprehensive mechanical properties. The room temperature tensile strength of the components obtained from the five sets of embodiments is consistently above 1520 MPa, all achieving the ultra-high strength standard of 1.5 GPa, and the elongation is not less than 10.0%, achieving a balance between strength and plasticity that is difficult to achieve with high-strength titanium alloys. Compared with conventional commercial titanium alloys, the performance of the components prepared by this invention is significantly improved: among them, Embodiment 4 has the best comprehensive performance, with a room temperature tensile strength reaching a peak of 1565 MPa, a high temperature tensile strength of 950 MPa at 600℃, and a room temperature specific strength as high as 350 kN·m / kg; Embodiment 3 exhibits the best plasticity, with an elongation of 11.0%, maintaining ultra-high strength while possessing optimal deformation capacity; the overall performance of the remaining Embodiments 1, 2, and 5 is stable and balanced, with the high temperature tensile strength at 600℃ maintained at around 900 MPa, making them suitable for long-term use in high-temperature and complex service environments. Meanwhile, none of the embodiments used expensive strategic metals such as V, Mo, and Nb, and significantly reduced raw material costs while achieving mechanical properties that are far superior to traditional titanium alloys.

[0059] The above content will be further elaborated by providing comparative examples below.

[0060] Comparative Example 1 This comparative example is based on the process parameters of Example 1, with only the alloy element ratios adjusted. The specific steps are as follows: Step 1, Raw material ratio and smelting: The mass content of Al element in Example 1 was adjusted to 3.5%, while the ratio of other raw materials and the smelting method remained the same as in Example 1. The pre-alloyed melt was prepared by suspension smelting.

[0061] Step 2, Helium atomization powder preparation: Pre-alloyed powder is prepared using the same helium atomization process as in Example 1.

[0062] Step 3, Powder Sieving and Drying: The powder is processed using the same sieving and heat-insulating drying process as in Example 1.

[0063] Step 4: Selective laser melting 3D printing: The same 3D printing parameters as in Example 1 are used for forming, and the component does not require heat treatment.

[0064] Tests showed that the component obtained in this comparative example was dense and crack-free, but due to the low Al content, the α phase stability was insufficient and the solid solution strengthening effect was weak. The room temperature tensile strength was 1351 MPa, the elongation was 12.0%, the 600℃ tensile strength was 728 MPa, and the room temperature specific strength was 296 kN·m / kg. The high temperature strength and specific strength were significantly lower than those of the embodiment of the present invention.

[0065] Comparative Example 2 This comparative example is based on the process parameters of Example 1, with only the alloy element ratios adjusted. The specific steps are as follows: Step 1, Raw material ratio and smelting: The Al element mass content in Example 1 is adjusted to 10%, while the ratio of other raw materials and the smelting method remain the same as in Example 1.

[0066] Step 2, Helium atomization powder preparation: Pre-alloyed powder is prepared using the same helium atomization process as in Example 1.

[0067] Step 3, Powder sieving and drying: The same powder processing technology as in Example 1 is used.

[0068] Step 4: Selective laser melting 3D printing: The same printing parameters as in Example 1 are used for forming, and the component does not require heat treatment.

[0069] Tests revealed that due to the excessively high Al content, brittle intermetallic compounds were easily formed inside the alloy in this comparative example, resulting in microcracks on the surface and inside of the component. The room temperature tensile strength was only 1128 MPa, the elongation dropped significantly to 5.0%, the tensile strength at 600℃ was 650 MPa, and the room temperature specific strength was 247 kN·m / kg, indicating a comprehensive deterioration in strength, plasticity, and high-temperature performance.

[0070] Comparative Example 3 This comparative example is based on the process parameters of Example 1, with only the alloy element ratios adjusted. The specific steps are as follows: Step 1, Raw material ratio and smelting: The Zr content in Example 1 is adjusted to 5%, while the ratio of other raw materials and the smelting method remain the same as in Example 1.

[0071] Step 2, Helium atomization powder making: The same powder making process as in Example 1 is adopted.

[0072] Step 3, Powder Sieving and Drying: A standardized powder sieving and drying process is adopted.

[0073] Step 4: Selective laser melting 3D printing: The component is prepared using the same printing parameters as in Example 1, without the need for heat treatment.

[0074] Tests showed that the comparative sample had too low a Zr content, which prevented it from effectively suppressing the precipitation of brittle ω phase and optimizing the microstructure. Although the component had no obvious cracks, its microstructure stability was poor, with a room temperature tensile strength of 1223 MPa, an elongation of 6.0%, a 600℃ tensile strength of 618 MPa, and a room temperature specific strength of 279 kN·m / kg. The overall mechanical properties were significantly reduced.

[0075] Comparative Example 4 This comparative example is based on the process parameters of Example 1, with only the alloy element ratios adjusted. The specific steps are as follows: Step 1, Raw material ratio and smelting: The mass content of Si element in Example 1 is adjusted to 4%, while the ratio of other raw materials and the smelting process remain unchanged.

[0076] Step 2, Helium atomization powder production: The same helium atomization powder production process as in Example 1 is adopted.

[0077] Step 3, Powder Sieving and Drying: A unified powder processing technology is adopted.

[0078] Step 4: Selective laser melting 3D printing: The same printing parameters as in Example 1 are used for forming, and the component does not require heat treatment.

[0079] Tests showed that the Si content in this comparative sample was severely excessive, which easily enriched and formed a brittle phase, disrupting the continuity of the matrix and causing microcracks in the component. The room temperature tensile strength was 1012 MPa, the elongation was only 3.0%, the 600℃ tensile strength was 560 MPa, and the room temperature specific strength was 231 kN·m / kg. Both the plasticity and strength reached extremely low levels.

[0080] Comparative Example 5 This comparative example is based on the optimal alloy ratio of Example 1, with only the 3D printing process parameters adjusted. The specific steps are as follows: Step 1, Raw material proportioning and smelting: The optimal alloy proportioning and suspension smelting process of Example 1 are used to prepare a homogeneous pre-alloyed melt.

[0081] Step 2, Helium atomization powder production: The same helium atomization powder production process as in Example 1 is adopted.

[0082] Step 3, Powder Sieving and Drying: The powder sieving and heat preservation drying process is the same as in Example 1.

[0083] Step 4: Selective laser melting 3D printing: Adjust the printing parameters to: laser power 100W, scanning speed 1500mm / s, and other parameters are the same as in Example 1. The component does not require heat treatment.

[0084] Testing revealed that this comparative example exhibited insufficient laser energy input, excessively fast scanning speed, and incomplete powder melting, resulting in numerous unfused defects and pores within the component. For example... Figure 6 As shown, the room temperature tensile curve of the alloy component in Comparative Example 5 exhibits low peak stress and small fracture strain, with no obvious plastic strengthening stage, similar to... Figure 5 In stark contrast to the excellent tensile properties of Example 1 shown, the strong plastic properties are significantly weakened.

[0085] Furthermore, the component obtained in this comparative example has a room temperature tensile strength of 1296 MPa, an elongation of 6.3%, a tensile strength at 600℃ of 750 MPa, and a room temperature specific strength of 289 kN·m / kg.

[0086] The mechanical property data of each comparative example are summarized in Table 2 below.

[0087] Table 2 Comparative alloy mechanical property data

[0088] As can be seen from Table 2, compared with Example 1 of the present invention, the performance degradation of each comparative sample is significant: Due to the low Al content, the solid solution strengthening of Comparative Example 1 is insufficient, the room temperature tensile strength decreases by 13.6% (from 1564 MPa to 1351 MPa), the high temperature tensile strength at 600℃ decreases by 23.0% (from 946 MPa to 728 MPa), and the high temperature stability is greatly weakened.

[0089] In Comparative Example 2, excessive Al induced the precipitation of brittle phases, resulting in microcracks in the component, a precipitous decrease in plasticity, a 53.3% decrease in elongation (from 10.7% to 5.0%), and a 27.9% decrease in room temperature tensile strength.

[0090] In Comparative Example 3, due to insufficient Zr content, the formation of brittle phase could not be suppressed, resulting in a 21.7% decrease in room temperature tensile strength, a 43.9% decrease in elongation, and a 34.7% decrease in high temperature strength.

[0091] Comparative Example 4 suffered the most severe performance degradation due to the serious excess of Si, which disrupted the continuity of the matrix. The room temperature tensile strength decreased by 35.3%, the elongation decreased by 72.0%, and the high temperature tensile strength decreased by 40.8%.

[0092] Comparative Example 5, due to unreasonable printing process parameters, had defects such as incomplete fusion in the component, resulting in a 17.1% decrease in room temperature tensile strength, a 41.1% decrease in elongation, and a 20.7% decrease in high temperature tensile strength.

[0093] Therefore, the above-mentioned α-Ti alloy material for laser 3D printing and its preparation method are adopted. Through the optimized ratio of Al, Zr and Si, the alloy material forms a dense and crack-free α single-phase structure in the printing state, which has ultra-high strength, good plasticity and excellent high-temperature mechanical properties, and the raw material cost is significantly reduced.

[0094] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0095] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An α-Ti alloy material for laser 3D printing, characterized in that, It includes, by mass percentage: Al 5.5~6.5%, Zr 9~13%, Si 0.2~0.4%, with total impurities not exceeding 0.1%, and the balance being Ti.

2. The α-Ti alloy material according to claim 1, characterized in that, The mass ratio of Zr to Al satisfies 0.5 ≤ Zr / Al ≤ 3.

3. The α-Ti alloy material according to claim 1, characterized in that, The α-Ti alloy material does not contain V, Mo, or Nb elements.

4. The α-Ti alloy material according to claim 1, characterized in that, The α-Ti alloy material is a spherical powder with an average particle size of 30 μm and a particle size range of 15 μm to 53 μm.

5. A method for preparing the α-Ti alloy material as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Weigh pure metal raw materials according to the preset proportions and components, and obtain a pre-alloyed melt through suspension melting; S2. The pre-alloyed melt is atomized and sieved to obtain α-Ti alloy powder material; S3. The α-Ti alloy powder material is printed into shape using selective laser melting process to prepare α-Ti alloy molded parts.

6. The preparation method according to claim 5, characterized in that, In step S2, the gas atomization is performed using helium atomization.

7. The preparation method according to claim 5, characterized in that, In step S3, the selective laser melting process parameters are: laser scanning power 155~255W, scanning speed 800~1200mm / s, layer thickness 0.02~0.08mm, and scanning spacing 0.1~0.2mm.

8. The preparation method according to claim 5, characterized in that, The α-Ti alloy formed part has an α single-phase structure, which is uniform, crack-free, and has high density.

9. The preparation method according to claim 8, characterized in that, The α-Ti alloy formed part has a room temperature tensile strength greater than 1.5 GPa, an elongation of not less than 10%, a specific strength of not less than 340 kN·m / kg, and a tensile strength at 600℃ greater than 900 MPa.

10. The preparation method according to claim 9, characterized in that, The α-Ti alloy formed parts are used for aircraft rudder structure components, engine components, hypersonic aircraft skin or nose cone.

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