Low-modulus high-performance beta titanium alloy and preparation method thereof

Abstract

The invention relates to a low-modulus high-performance beta titanium alloy and an additive manufacturing method thereof, and belongs to the technical field of metal materials and additive manufacturing. The titanium alloy is prepared from the following components in percentage by mass: 14.8 percent to 16.8 percent of Nb, 8.2 percent to 10.2 percent of Ta, 9.0 percent to 11.0 percent of Zr, 6.7 percent to 8.7 percent of Sn and the balance of Ti and inevitable impurity elements. According to the preparation method, alloy powder with specific components is prepared through a high-power and high-scanning-rate selective laser melting (L-PBF) method to obtain a titanium alloy blank, heat treatment is not needed, and the density of the prepared titanium alloy is larger than or equal to 99.5%, the elasticity modulus is smaller than or equal to 40 GPa, the room-temperature tensile strength is larger than or equal to 710 MPa, and the ductility is larger than or equal to 24%. The titanium alloy designed and prepared through the method has low modulus and high-strength plasticity, the cost is low, the process is simple and controllable, and wide application of the additive manufacturing titanium alloy in the biomedical field can be achieved.

Description

Technical Field

[0001] The present invention relates to a low-modulus, high-performance beta titanium alloy and an additive manufacturing method thereof, belonging to the technical field of metal materials and additive manufacturing. Background Art

[0002] Additive Manufacturing (AM), also known as 3D printing, is a type of rapid prototyping technology. A computer creates a three-dimensional model, and a printing device then deposits material point by point, layer by layer, ultimately creating a personalized product. Its core principle is "layered manufacturing, layer by layer." Compared to traditional manufacturing processes such as casting or forging, AM not only improves material utilization but also significantly reduces production time and costs. The resulting parts from AM have a smooth surface and are actively controllable during the molding process, enabling the creation of personalized products with controlled shape and properties, making them popular in the biomedical industry. Laser powder bed melting (L-PBF) uses a laser as a heat source to slice and path-plan a designed 3D CAD model. The metal powder layers are heated and melted layer by layer along the designed path, ultimately creating the part. L-PBF technology is commonly used to manufacture small, complex parts. The process offers advantages such as high dimensional accuracy and the absence of supports.

[0003] Titanium alloys have low density, high strength, high corrosion resistance and good biocompatibility, and are widely used in the biomedical field as a replacement material for hard tissues such as human bones and teeth. However, common biomedical titanium alloys, such as Ti6Al4V, Ti5Al 2.5 Fe and Ti6Al7Nb have elastic moduli several times higher than that of bone (20-30 GPa). This mismatch in elastic modulus between implants and bone can easily trigger "stress shielding," leading to functional degradation and resorption of surrounding bone tissue, resulting in implant loosening or fracture. Furthermore, research has shown that Al and V are biotoxic, with V even being more toxic than Cr and Ni. When V-containing titanium alloy components are implanted in patients for extended periods, V ions can accumulate in various organs, potentially inducing cancer and causing secondary damage. Therefore, the development of new medical titanium alloys is a current research hotspot. β-type titanium alloys, containing biocompatible elements such as Nb, Zr, Ta, Mo, and Sn, are favored by researchers for their lower elastic modulus, superior biocompatibility, and corrosion resistance. However, most metastable β-type titanium alloys are prone to stress-induced phase transformations and stress-induced twinning, resulting in yielding at relatively low stresses. This increases the risk of post-yielding plastic deformation, implant displacement, and even bone tearing after implantation. In addition to meeting certain strength requirements, medical titanium alloy implants also require attention to their elastic modulus. Currently, composition design and texture control are the two main strategies for reducing the elastic modulus.

[0004] The composition design methods of titanium alloys include the molybdenum equivalent method, the electron concentration method, the d-electron theory and the semi-empirical method. The designed β-titanium alloys include Ti-36Nb-Ta-4.6Zr, Ti-29Nb-13Ta-4Mo, Ti-35Nb-7Zr-Ta, Ti-6Mo-Zr, Ti-36Nb-2Ta-3Zr-0.3O, Ti-24Nb-4Zr-8Sn, Ti-25.6Nb-19.4Ta, etc. (CN202411429589.7, CN202411677398.2, CN201510728193.7, CN202410378278.6, CN202410018577.9). Their elastic modulus is generally greater than 40 GPa. In other words, it is very difficult to further reduce the elastic modulus of the alloy through composition design.

[0005] The present invention adds appropriate amounts of β-stabilizing elements Nb, Ta, Zr, and Sn to the titanium alloy to inhibit the transformation of the β phase to other phases, thereby obtaining a single β-phase titanium alloy with a lower elastic modulus; the alloy is regulated by the additive manufacturing L-PBF technology with appropriate process parameters. <001> Orientation, further reducing the elastic modulus of the alloy. Combined with the extremely high cooling rate (10 5 ~10 7 ℃ / s), inducing high-density dislocations and twins and other crystal defects to achieve alloy strengthening; thus obtaining a biomedical titanium alloy with low elastic modulus, high strength and high plasticity. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the first purpose of the present invention is to provide a low modulus, high strength and toughness titanium alloy composition ratio. The low modulus, high performance titanium alloy provided by the present invention adds β stabilizing elements - Zr and Sn elements to the titanium alloy, retaining a single β phase, which greatly reduces the elastic modulus of the material; and by regulating the content of alloying elements, it can be prepared under high power and high scanning rate additive manufacturing processes, achieving strong <001> The elastic modulus is reduced by regulating the texture; by dissolving Zr and Sn elements, the tensile strength of titanium alloy at room temperature and high temperature is increased at the same time, the martensite transformation temperature Ms is lowered, and by stabilizing the β phase and reducing the content of the brittle ω phase, the plasticity of the material is improved while the strength is increased.

[0007] The second purpose of the present invention is to provide a set of additive manufacturing processing parameters for low modulus high performance titanium alloy, including laser power and laser scanning rate. The preparation method of the present invention regulates the structure and texture of titanium alloy by adjusting the additive manufacturing processing parameters, and obtains strong <001> The L-PBF process creates a directional texture, thereby reducing the material's elastic modulus. The large temperature gradient of the L-PBF process introduces crystal defects such as high-density dislocations, increasing the alloy's strength and further optimizing its mechanical properties. The titanium alloy produced by this method has a low elastic modulus and combines good strength with good plasticity, effectively expanding the application of additively manufactured titanium alloys in the biomedical field.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] The present invention provides a low-modulus, high-performance titanium alloy. The low-modulus, high-performance titanium alloy consists of a titanium alloy matrix and Nb, Ta, Zr, and Sn elements solid-dissolved in the titanium alloy matrix. The mass fractions of the Nb, Ta, Zr, and Sn elements are 14.8% to 16.8%, 8.2% to 10.2%, 9.0% to 11.0%, and 6.7% to 8.7%, respectively. The remainder is Ti and unavoidable impurity elements.

[0010] Preferably, the present invention provides a low modulus, high strength and toughness titanium alloy, wherein the titanium alloy is composed of the following components, by mass percentage: Nb 15.6-16%, Ta 9-9.4%, Zr 9.8-10.2%, Sn 7.5-7.9%, with the balance being Ti and unavoidable impurity elements. In a preferred embodiment, the titanium alloy is composed of the following components, by mass percentage: Nb 15.8%, Ta 9.2%, Zr 10%, Sn 7.7%, with the balance being Ti and unavoidable impurity elements.

[0011] In the present invention, Nb, Ta, Zr, and Sn are common biomedical β-titanium alloy solid solution elements in titanium alloys. Ta is a β-stabilizing element that can lower the β-phase transition temperature of the titanium alloy and increase the β-phase stability. Zr and Sn have high solid solubility in the β-titanium alloy, which can simultaneously improve the tensile strength of the titanium alloy at room temperature and high temperature, lower the martensitic start transition temperature, Ms, and stabilize the β phase, reducing the content of the brittle ω phase. This improves both strength and plasticity. The alloying elements Nb, Ta, Zr, and Sn dissolve into the titanium alloy matrix lattice to form a solid solution, forcing lattice distortion and increasing dislocation density, thereby strengthening the alloy.

[0012] The present invention discloses a method for preparing a low-modulus, high-performance titanium alloy. The method comprises the following steps: subjecting Ti-Nb-Ta-Zr-Sn alloy powder with a specific composition to laser selective melting (L-PBF) to obtain a titanium alloy embryo. The deposited titanium alloy embryo is a low-elastic modulus, high-performance alloy.

[0013] In a preferred embodiment, the laser selective melting is performed under argon protection, and the scanning method is a zigzag scan, with an interlayer rotation of 67° or 90°, preferably 67°. By adopting the scanning method of the present invention and the interlayer rotation, the residual stress of the alloy material can be reduced and the performance can be improved.

[0014] In a preferred embodiment, the parameters of the laser selective melting are: laser power 200-400 W, scanning speed 750-1500 mm / s, overlap distance 0.12-0.16 mm, powder thickness 0.02-0.04 mm, and focal spot size 0.025-0.035 mm. In the present invention, by controlling the parameters of the laser selective melting within the range of the present invention, a dense and defect-free alloy material can be obtained, and it has strong <001> Directional texture. That is, the prepared β titanium alloy has strong <001> Texture orientation, <001> The texture strength is greater than 45%. The present invention realizes the control of texture through the synergistic effect of process and ingredients, and the obtained product has strong <001> Texture orientation, cubic crystal <001> Orientation has the lowest elastic modulus, since the product obtained by the present invention has <001> Oriented alloy, so its elastic modulus in the load-bearing direction is lower than that of existing products, which can effectively solve the "stress shielding" phenomenon.

[0015] In a preferred embodiment, the parameters of the laser selective melting are: laser power 400~450W, scanning rate 700~800mm / s, powder layer thickness 0.02~0.04mm, overlap distance 0.12~0.16mm, and focal spot size 0.025~0.035mm.

[0016] In the actual operation process, the titanium alloy block obtained by laser selective melting has a size of 60×15×5 mm, of which 5 mm is the deposition height direction.

[0017] In a preferred solution, after printing is completed, the deposited sample is cut from the substrate using an electric spark wire cutting machine to obtain a titanium alloy sample with ideal performance.

[0018] Through the optimization of the present invention, the obtained product has a higher strength than the existing technology while ensuring that the elastic modulus is less than 40GPa, and at the same time its elongation is much higher than the existing products.

[0019] The alloy obtained in this invention is deposited during additive manufacturing and does not undergo heat treatment, yet it achieves a low elastic modulus combined with excellent strength and plasticity. The resulting printed blanks have a density of ≥99.5% and an elastic modulus of ≤40 GPa. They also exhibit room-temperature tensile strength of ≥710 MPa and elongation of ≥24%. After optimization, the resulting printed blanks have an elastic modulus of ≤34 GPa, a room-temperature tensile strength of ≥710 MPa, and an elongation of ≥25%.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention proposes a biomedical titanium alloy with a new alloying element ratio, and obtains a high-performance titanium alloy with low elastic modulus through laser selective melting technology.

[0022] 2. The appropriate amount of Nb, Ta, Zr, and Sn dissolved in the low-elastic modulus, high-performance titanium alloy of this invention not only contributes to biocompatibility but also fully utilizes the solubility of each element in β-Ti, enhancing the alloy's strength through solid solution strengthening. The β-stabilizing elements inhibit the transformation of the β phase into other phases, resulting in a single β-phase titanium alloy with a lower elastic modulus. Furthermore, by regulating the alloying element content, the alloy can be fabricated using high-power and high-scan rate additive manufacturing processes.

[0023] 3. The present invention adopts laser selective melting (L-PBF) technology to prepare low elastic modulus and high toughness β titanium alloy. Compared with traditional casting and forging processes, laser selective melting technology can not only change the shape of the molten pool by adjusting the additive manufacturing parameters, but also achieve strong <001> Texture orientation reduces the elastic modulus of the alloy; and additive manufacturing can form parts with complex shapes in one step, greatly shortening the product delivery cycle and at the same time greatly improving the utilization rate of raw materials.

[0024] 4. The present invention does not require a complicated preparation process. Without heat treatment, the resulting printed blank has an extremely low elastic modulus (≤40GPa) while having high strength and good plasticity. Its room temperature tensile strength is ≥720MPa and its elongation is ≥25%, overcoming the contradiction that the elastic modulus and strength cannot be improved simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a physical picture of the printed part;

[0026] Figure 2 The engineering stress-strain curves of the room temperature tensile test of the low elastic modulus high performance titanium alloy obtained in Examples 1 to 5 are:

[0027] Figure 3This is the inverse pole figure of the low elastic modulus and high performance titanium alloy obtained in Examples 1 to 5. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0029] Example 1

[0030] A low-modulus, high-performance titanium alloy has the following chemical composition, by mass percentage: 15.8% Nb, 9.2% Ta, 10.0% Zr, and 7.7% Sn, with the remainder being Ti and unavoidable impurities. The titanium alloy is prepared by purchasing custom powder from the market. Then, a Ti-15.8Nb-9.2Ta-10.0Zr-7.7Sn alloy is prepared using selective laser melting (SLM). The SLM preparation parameters include a laser power of 200W, a scanning rate of 750mm / s, a powder layer thickness of 0.03mm, an overlap distance of 0.12mm, a focal spot size of 0.03mm, a zigzag scanning pattern, a 67° inter-layer rotation, and a protective atmosphere of high-purity argon (99.99%). The alloy blocks were then processed by electrospark cutting (EDC). The as-deposited alloy samples were then processed into tensile specimens for testing the room-temperature tensile properties. The size of the tensile specimen gauge section is 10×2×1.5mm. The measured tensile engineering stress-strain curve is shown in the figure. <001> The texture content is 2.2%, and the final measured results show that the elastic modulus of the deposited state is 53.23 GPa, the yield strength is 569.39 MPa, the tensile strength is 800.01 MPa, and the uniform elongation is 8.94%.

[0031] Example 2

[0032] A low-modulus, high-performance titanium alloy has the following chemical composition, by mass percentage: 15.8% Nb, 9.2% Ta, 10.0% Zr, 7.7% Sn, with the remainder being Ti. This titanium alloy is prepared by purchasing commercially available custom powder. A Ti-15.8Nb-9.2Ta-10.0Zr-7.7Sn alloy is then prepared using selective laser melting (SLM). The SLM preparation parameters include a laser power of 300W, a scanning rate of 1500mm / s, a powder layer thickness of 0.03mm, an overlap distance of 0.12mm, a focal spot size of 0.03mm, a zigzag scanning pattern, a 67° inter-layer rotation, and a protective atmosphere of high-purity argon (99.99%). The alloy blocks were then processed by electrospark cutting (EDC). The as-deposited alloy samples were then processed into tensile specimens for testing the room-temperature tensile properties. The size of the tensile specimen gauge section is 10×2×1.5mm. The measured tensile engineering stress-strain curve is shown in the figure. <001> The texture content is 1.2%, and the final measured results show that the elastic modulus of the deposited state is 41.29 GPa, the yield strength is 607.14 GPa, the tensile strength is 758.49 MPa, and the uniform elongation is 14.23%.

[0033] Example 3

[0034] A low-modulus, high-performance titanium alloy has the following chemical composition, by mass percentage: 15.8% Nb, 9.2% Ta, 10.0% Zr, 7.7% Sn, with the remainder being Ti. This titanium alloy is prepared by purchasing a custom powder of the composition from the market. Then, a Ti-15.8Nb-9.2Ta-10.0Zr-7.7Sn alloy is prepared using selective laser melting (SLM). The SLM preparation parameters used are: a laser power of 300W, a scanning rate of 750mm / s, a powder layer thickness of 0.03mm, an overlap distance of 0.12mm, a focal spot size of 0.03mm, a zigzag scanning pattern, a 67° inter-layer rotation, and a protective atmosphere of high-purity argon (99.99%). The sample was processed into an alloy block by electrospark cutting. The as-deposited alloy sample was then processed into tensile specimens for testing the room-temperature tensile properties of the material. The size of the tensile specimen gauge section is 10×2×1.5mm. The measured tensile engineering stress-strain curve is shown in the figure. <001> The texture content is 33.4%, and the final measured results show that the elastic modulus of the deposited state is 36.52 GPa, the yield strength is 694.05 MPa, the tensile strength is 752.41 MPa, and the uniform elongation is 24.02%.

[0035] Example 4

[0036] A low-modulus, high-performance titanium alloy has the following chemical composition, by mass percentage: 15.8% Nb, 9.2% Ta, 10.0% Zr, 7.7% Sn, with the remainder being Ti. This titanium alloy is prepared by purchasing commercially available custom powder. A Ti-15.8Nb-9.2Ta-10.0Zr-7.7Sn alloy is then prepared using selective laser melting (SLM). The SLM preparation parameters include a laser power of 400W, a scanning rate of 1000mm / s, a powder layer thickness of 0.03mm, an overlap distance of 0.12mm, a focal spot size of 0.03mm, a zigzag scanning pattern, a 67° inter-layer rotation, and a protective atmosphere of high-purity argon (99.99%). The alloy blocks were then processed by electrospark cutting (EDC). The as-deposited alloy samples were then processed into tensile specimens for testing the room-temperature tensile properties. The size of the tensile specimen gauge section is 10×2×1.5mm. The measured tensile engineering stress-strain curve is shown in the figure. <001> The texture content is 33.5%, and the final measured results show that the elastic modulus of the deposited state is 33.13 GPa, the yield strength is 664.00 MPa, the tensile strength is 764.94 MPa, and the uniform elongation is 14.97%.

[0037] Example 5

[0038] A low-modulus, high-performance titanium alloy has the following chemical composition, by mass percentage: 15.8% Nb, 9.2% Ta, 10.0% Zr, 7.7% Sn, with the remainder being Ti. This titanium alloy is prepared by purchasing commercially available custom powder. A Ti-15.8Nb-9.2Ta-10.0Zr-7.7Sn alloy is then prepared using selective laser melting (SLM). The SLM preparation parameters include a laser power of 400W, a scanning rate of 750mm / s, a powder layer thickness of 0.03mm, an overlap distance of 0.12mm, a focal spot size of 0.03mm, a zigzag scanning pattern, a 67° inter-layer rotation, and a protective atmosphere of high-purity argon (99.99%). The alloy blocks were then processed by electrospark cutting (EDC). The as-deposited alloy samples were then processed into tensile specimens for testing the room-temperature tensile properties of the material. The size of the tensile specimen gauge section is 10×2×1.5mm. The measured tensile engineering stress-strain curve is shown in the figure. <001> The texture content is 49.1%, and the final measured results show that the elastic modulus of the deposited state is 33.06 GPa, the yield strength is 698.7 MPa, the tensile strength is 712.19 MPa, and the uniform elongation is 29.00%.

[0039] Comparative Example 1

[0040] The other conditions are the same as those in Example 1. The alloy powder with specific composition is added into the vacuum melting furnace for melting, and then suction casting is performed to obtain alloy ingots. The alloy embryo preparation method is replaced by the traditional casting method. <001> The texture content is only 0.5%, and the elastic modulus of the final sample is 44.83GPa, the yield strength is 229.37MPa, the tensile strength is 632.98MPa, and the uniform elongation is 7.64%.

[0041] Comparative Example 2

[0042] Other conditions are the same as those in Example 5, except that the Ti-15.8Nb-9.2Ta-10.0Zr-7.7Sn alloy powder is replaced with Ti-24Nb-4Zr-7.9Sn powder. The final sample has an elastic modulus of 53 GPa, a yield strength of 563 MPa, a tensile strength of 665 MPa, and a uniform elongation of 13.8%.

[0043] Comparative Example 3

[0044] Other conditions are the same as those in Example 5, except that the Ti-15.8Nb-9.2Ta-10.0Zr-7.7Sn alloy powder is replaced with Ti-18Nb-0.70Sn powder. <001> The texture content is 39.7%, and the elastic modulus of the final sample is 39 GPa, the yield strength is 803 MPa, the tensile strength is 945 MPa, and the uniform elongation is 15%.

[0045] Comparative Example 4

[0046] The other conditions were the same as those in Example 5. The alloy powder of the specific composition was added to a 40 mm graphite mold and the samples were made by spark plasma sintering technology. The specific parameters of the molding were: sintering temperature 1100 ° C, heating rate 100 ° C / min, holding time 10 min, sintering pressure 40 MPa. The samples prepared by spark plasma sintering method were statistically analyzed. <001> The texture content is only 8.1%, the elastic modulus of the sample is 46.75GPa, the yield strength is 682.00MPa, the tensile strength is 762.03MPa, and the uniform elongation is 17.43%.

[0047] Comparative Example 5

[0048] Other conditions are the same as those in Example 5, wherein the parameters used in the laser selective melting preparation process are a laser power of 400W and a scanning rate of 1500mm / s. Finally, warping occurs during the printing process, the sample has obvious macroscopic defects, cannot be formed, and performance testing cannot be performed.

[0049] Table 1 shows the Ti-Nb-Ta-Zr-Sn titanium alloy prepared by the present invention. <001> Comparison of texture content with existing titanium alloys.

[0050] Table 2 shows the comparison of mechanical properties between the Ti-Nb-Ta-Zr-Sn titanium alloy prepared by the present invention and existing titanium alloys.

[0051]

[0052]

[0053] Matters not covered by this invention are known in the art. The above embodiments are intended only to illustrate the technical concepts and features of this invention. Their purpose is to enable those skilled in the art to understand the contents of this invention and implement them accordingly. They are not intended to limit the scope of protection of this invention. Any equivalent changes or modifications made in accordance with the spirit and essence of this invention are intended to be covered by the scope of protection of this invention.

Claims

1. A low modulus, high strength and toughness titanium alloy, characterized by: The low modulus, high-performance titanium alloy consists of a titanium alloy matrix and Nb, Ta, Zr, and Sn elements dissolved in the titanium alloy matrix. The mass fractions of Nb, Ta, Zr, and Sn in the titanium alloy are 14.8% to 16.8%, 8.2% to 10.2%, 9.0% to 11.0%, and 6.7% to 8.7%, respectively, and the remainder is Ti and unavoidable impurity elements.

2. The low modulus, high strength and toughness titanium alloy according to claim 1, characterized in that: The titanium alloy consists of the following components in percentage by mass: Nb 15.6-16%, Ta 9-9.4%, Zr 9.8-10.2%, Sn 7.5-7.9%, and the balance being Ti and unavoidable impurity elements.

3. The low modulus, high strength and toughness titanium alloy according to claim 2, characterized in that: The titanium alloy consists of the following components in percentage by mass: Nb 15.8%, Ta 9.2%, Zr 10%, Sn 7.7%, and the balance being Ti and unavoidable impurity elements.

4. A method for preparing a high-strength and high-toughness titanium alloy according to any one of claims 1 to 3, characterized in that: A titanium alloy embryonic body is obtained by using a laser selective melting technique to obtain alloy powder with a specific composition prepared by gas atomization.

5. The method for preparing a low modulus, high strength and high toughness titanium alloy according to claim 4, characterized in that: The Ti-Nb-Ta-Zr-Sn alloy powder with a specific composition is atomized by an electrode induction melting gas atomization method, and then the alloy powder with a size range of 15-53 μm is separated by a vibrating screen.

6. The method for preparing a low modulus, high strength and high toughness titanium alloy according to claim 4, characterized in that: The parameters of the laser selective melting are: laser power 350-450 W, scanning speed 950-1050 mm / s, overlap distance 0.12-0.16 mm, powder thickness 0.02-0.04 mm, and focal spot size 0.025-0.035 mm; the laser selective melting is carried out under argon protection, the scanning mode is zigzag scanning, and the interlayer rotation is 67° or 90°.

7. The method for preparing a low modulus, high strength and high toughness titanium alloy according to claim 6, characterized in that: The parameters of the laser selective melting are: laser power 350-450 W, scanning speed 700-800 mm / s, overlap distance 0.12-0.16 mm, powder thickness 0.02-0.04 mm, and focal spot size 0.025-0.035 mm; the laser selective melting is carried out under argon protection, the scanning mode is zigzag scanning, and the interlayer rotation is 67° or 90°.

8. The method for preparing a low modulus, high strength and high toughness titanium alloy according to claim 6, characterized in that: The prepared β alloy is in the additive manufacturing deposition state. <001> The texture strength is greater than 45%, and the deposited sample is not heat treated, which can achieve a combination of low elastic modulus and good strength-plasticity.

9. The method for preparing a low modulus, high strength and toughness titanium alloy according to claim 6, characterized in that: The elastic modulus of the printed blank is ≤40GPa; at the same time, the room temperature tensile strength of the printed blank is ≥710MPa, and the elongation is ≥24%.

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