Preparation method of high-strength and high-plasticity low-modulus beta titanium alloy plate

Abstract

The application provides a preparation method of a high-strength plastic low-modulus beta type titanium alloy plate, and the preparation method of the titanium alloy plate is as follows: pure niobium blocks, pure zirconium blocks, TiO2 particles, pure titanium blocks and pure tin blocks are stacked from top to bottom in a vacuum arc melting furnace, and repeated overturning melting is performed 5-6 times to obtain alloy ingots; the alloy ingots are subjected to solid solution treatment, and are cooled after the solid solution treatment to obtain a solid solution alloy; the solid solution alloy is subjected to physical deep cooling; then the solid solution alloy is cut into a plurality of plate blanks, and the plate blanks are subjected to polishing treatment; the plate blanks are subjected to multi-pass cold rolling treatment, the cold-rolled plate blanks are vacuum packaged, and annealing treatment is performed based on heat and magnetism, so that the final product is obtained. Based on alloy component design, a beta type Ti-Nb-Sn-Zr-O alloy is prepared by using vacuum arc melting, and the titanium alloy plate prepared by the application has low modulus, high tensile strength and good room temperature strength plasticity.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy technology, specifically a method for preparing a high-strength, low-modulus β-type titanium alloy plate. Background Technology

[0002] With social development and continuous advancements in medical technology, people are paying increasing attention to their health and quality of life, especially demanding higher reliability from biomedical materials. Currently, commonly used biomedical metallic materials mainly fall into three categories: medical-grade stainless steel, cobalt-based alloys, and titanium alloys. However, medical-grade stainless steel and cobalt-based alloys contain large amounts of alloying elements such as Al, V, Fe, Ni, and Co, which exhibit strong cytotoxicity. Furthermore, due to their high elastic modulus and poor corrosion resistance, they have not been widely used in fields such as medical devices.

[0003] Titanium alloys possess excellent specific strength, low elastic modulus, and good corrosion resistance, making them suitable for use in biomedical materials. Alpha-type titanium alloys have relatively low strength, making them unsuitable for supporting the weight of larger body parts and limiting their application to oral cavity and small bone repairs. While α+β-type alloys, represented by Ti-6Al-4V, exhibit excellent mechanical properties and good corrosion resistance, the cytotoxicity of V and Al elements in these alloys is detrimental to bone growth and may pose a risk of neurological disorders. Furthermore, the elastic modulus of Ti-6Al-4V alloys (~110 GPa) is higher than that of bone (~30 GPa), subjecting implants to greater stress and potentially leading to failure. β-type titanium alloys, with their excellent biocompatibility and mechanical properties, are considered promising biomedical materials.

[0004] Currently, to obtain medical titanium alloys with an elastic modulus close to that of human bone, engineers have developed more than 20 types of β-type medical titanium alloys with lower elastic moduli across various alloy systems. These new materials have reduced their elastic modulus by approximately 40%, reaching 60-65 GPa, but this is still significantly higher than that of human bone (10-30 GPa). The stress matching and transmission between implanted devices and bone tissue has not been completely resolved, degenerative changes such as bone resorption cannot be eliminated, and failure due to loosening of implanted devices remains a significant concern. Furthermore, the tensile strength of current β-type medical titanium alloys is relatively low, below 900 MPa. This low tensile strength and high modulus will limit the widespread application of β-type titanium alloys in the biomedical field, necessitating further improvements.

[0005] Therefore, it is necessary to develop a method for preparing β-type titanium alloy plates, so that the prepared plates have both a lower elastic modulus and a higher tensile strength, thereby improving the biomechanical properties of β-type titanium alloy plates and further expanding their application fields. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing a high-strength, low-modulus β-type titanium alloy plate. Based on alloy composition design, a β-type Ti-Nb-Sn-Zr-O alloy is prepared using vacuum arc melting. The titanium alloy is then subjected to solution treatment and physical cryogenic cooling. Subsequently, a high-strength, low-modulus titanium alloy plate is obtained through cold rolling and annealing processes. The titanium alloy plate prepared by this invention has a low modulus, high tensile strength, and good room temperature strength and plasticity.

[0007] To achieve the above objectives, the specific solution adopted by the present invention is as follows: A method for preparing a high-strength, low-modulus β-type titanium alloy plate mainly includes the following steps: Step 1: Weigh out pure titanium blocks, pure niobium blocks, pure tin blocks, pure zirconium blocks, and TiO2 particles according to the chemical composition of the titanium alloy. Stack the raw materials in the vacuum arc melting furnace from top to bottom in the order of pure niobium blocks, pure zirconium blocks, TiO2 particles, pure titanium blocks, and pure tin blocks. Repeatedly turn and melt 5 to 6 times to obtain alloy ingots. Step 2: Place the alloy ingot in a tube furnace and heat it to 800~1000℃ under an argon atmosphere for solution treatment for 0.5~2 hours. After solution treatment, cool it to obtain a solution alloy. Step 3: Place the solid solution alloy in a beaker containing alcohol, add liquid nitrogen to keep the alcohol temperature at -30~-50℃, and perform physical cryogenic cooling. Step 4: Cut the solid solution alloy into several slabs and grind the slabs. Step 5: Perform multiple cold rolling processes on the slab, with a total rolling deformation of 80% to 90%. Step 6: Vacuum seal the cold-rolled slab and treat it at a temperature of 350-450℃ and a magnetic field of 1-15T for 0.5-2 hours to obtain a high-strength, low-modulus β-type titanium alloy plate.

[0008] Furthermore, the composition of the alloy ingot by mass percentage includes: Nb 35~40%, Sn 5~10%, Zr 8.5~10%, O 0.6~1%, and the remainder is Ti.

[0009] Furthermore, in step two, during the solution treatment, the gas pressure inside the tubular furnace is not higher than 0.02 MPa, and the argon atmosphere flow rate is 10~30 sccm.

[0010] Furthermore, in step two, after solution treatment, the solution is cooled by water quenching or ice-salt water quenching.

[0011] Furthermore, in step four, the slab undergoes 8 to 12 cold rolling passes, with a single rolling deformation of 5 to 8%.

[0012] Beneficial effects: 1) In this invention, Nb is a β-phase stabilizing element in the titanium alloy. Based on this, the addition of biocompatible elements such as Sn and Zr can achieve a low elastic modulus while simultaneously improving the alloy's strength. O element has a unique strengthening effect and plastic deformation mechanism, and its superior occupancy can reduce the elastic modulus of the alloy system. The Ti-Nb-Sn-Zr-O β-titanium alloy provided by this invention, compared to other α-type and α+β-type titanium alloys, achieves high strength and elongation while exhibiting a lower elastic modulus.

[0013] 2) This invention involves deep cryogenic cooling of the solid solution alloy before cold rolling, which significantly improves its plastic deformation capacity while ensuring strength. This is mainly due to the following reasons: the crystal lattice contracts upon cooling, reducing the interatomic spacing, and the strong internal stress causes a certain degree of lattice distortion, resulting in a large number of dislocations within the grains; at lower temperatures, the number of operable slip systems in the titanium alloy decreases, allowing some slip systems to be retained.

[0014] 3) This invention performs annealing on titanium alloys after cold rolling based on the coupling effect of magnetic field and heat, which makes up for the defects of cold-rolled titanium alloys and effectively controls the microstructure under non-equilibrium solidification conditions, so as to greatly improve the strength and plasticity of the alloy after cold rolling, so as to meet the requirements of more demanding service environments.

[0015] 4) This invention provides a high-strength, low-modulus Ti-Nb-Sn-Zr-O β-titanium alloy, which, compared with other α-type and α+β-type titanium alloys, has a lower elastic modulus while meeting the requirements of high strength and elongation. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the preparation process of the titanium alloy plate in this invention.

[0017] Figure 2 This is a transmission image of the titanium alloy plate prepared in Example 1 of this invention. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. 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 protection scope of the present invention.

[0019] Please refer to Figure 1 This invention provides a method for preparing a high-strength, low-modulus β-type titanium alloy plate, comprising the following steps: Step 1: Weigh out pure titanium blocks, pure niobium blocks, pure tin blocks, pure zirconium blocks, and TiO2 particles according to the chemical composition of the titanium alloy. Stack the raw materials in a water-cooled copper crucible non-consumable vacuum arc melting furnace in the order of pure niobium blocks, pure zirconium blocks, TiO2 particles, pure titanium blocks, and pure tin blocks from top to bottom. Repeatedly turn and melt 5-6 times to ensure the uniformity of the composition of the melted sample, and obtain a button-shaped alloy ingot. The melting points of the metals are Nb > Zr > TiO2 > Ti > Sn, and the placement order is from top to bottom, from high melting point to low melting point. Step 2: The alloy ingot obtained in Step 1 is heated to 800~1000℃ in a tube furnace under argon atmosphere protection for solution treatment, and the homogenization time is 0.5~2h. After the treatment, it is quenched with water or ice-salt water to obtain a solution alloy. The gas pressure in the tube furnace is not higher than 0.02MPa and the argon atmosphere flow rate is 10~30sccm. Step 3: Place the solid solution alloy from Step 2 into a beaker containing alcohol, add a small amount of liquid nitrogen to keep the temperature of the alcohol liquid at -30~-50℃, and perform physical cryogenic cooling on the solid solution alloy. Step 4: Use electrode wire to cut the cooled solution alloy into rolled slabs, and use a grinding wheel to grind them to remove the surface oxide scale. Step 5: Perform multi-pass cold rolling on the solid solution alloy from Step 3, with 8 to 12 passes, a single rolling deformation of 5 to 8%, and a total rolling deformation of 80% to 90%.

[0020] Step 6: Vacuum seal the cold-rolled slab from Step 4 and process it at a temperature of 350-450℃, a magnetic field of 1-15T, and a processing time of 0.5-2h to obtain the final titanium alloy plate.

[0021] In step one, the raw materials must be placed in descending order of melting point. The melting points of the metals are Nb > Zr > TiO2 > Ti > Sn, and the placement order is from top to bottom. The alloy, placed from high to low melting points, needs to be repeatedly turned and melted 5-6 times to ensure the uniformity of the composition of the molten sample. The alloy ingot composition in step one, by mass percentage, contains: 35-40% Nb, 5-10% Sn, 8.5-10% Zr, 0.6-1% oxygen, and the remainder Ti.

[0022] The technical solution of the present invention will be described in detail below with reference to specific embodiments. All raw materials are commercially available.

[0023] Example 1

[0024] A high-strength, low-modulus titanium alloy and its preparation method, comprising the following steps: Step 1: Weigh out pure titanium blocks, pure niobium blocks, pure tin blocks, pure zirconium blocks, and TiO2 particles according to the chemical composition of the titanium alloy. Stack the raw materials in the order of pure niobium blocks, pure zirconium blocks, TiO2 particles, pure titanium blocks, and pure tin blocks in a water-cooled copper crucible non-consumable vacuum arc melting furnace from top to bottom. Repeatedly turn and melt 5-6 times to obtain a button-shaped alloy ingot. The alloy ingot material composition (mass percentage) is: Nb 35%, Sn 7%, Zr 8.5%, O 0.6%, with the balance being Ti.

[0025] Step 2: The alloy ingot from Step 1 is heated to 1000℃ in a tube furnace under argon atmosphere protection for solution treatment, homogenization time is 1 hour, and then quenched with cold water to obtain the solution alloy. Step 3: Place the solid solution alloy from Step 2 into a beaker containing alcohol, add a small amount of liquid nitrogen to keep the temperature of the alcohol liquid at -50℃, and perform physical cryogenic cooling on the solid solution alloy. Step 4: Use electrode wire to cut the cooled solution alloy into rolled slabs, and use a grinding wheel to grind them to remove the surface oxide scale. Step 5: Perform multi-pass cold rolling on the solid solution alloy from Step 3, with 8 passes and a single rolling deformation of 6%. Step 6: Vacuum seal the cold-rolled slab from Step 4 and process it under conditions of 450℃, 12T magnetic field, and 2h processing time.

[0026] Figure 2 The transmission image of the titanium alloy plate prepared in Example 1 is shown below. Figure 2 It can be seen that the prepared alloy is a single β phase, indicating that the β phase of the alloy has good stability.

[0027] Example 2

[0028] The difference between this embodiment and Embodiment 1 is that in step one, the alloy ingot material composition (mass percentage) is: Nb 35%, Sn 7%, Zr 8.5%, O 0.7%, with the balance being Ti.

[0029] Example 3

[0030] The difference between this embodiment and Embodiment 1 is that in step one, the alloy ingot material composition (mass percentage) is: Nb 35%, Sn 7%, Zr 8.5%, O 0.9%, with the balance being Ti.

[0031] Example 4

[0032] The difference between this embodiment and Embodiment 1 is that in step one, the alloy ingot material composition (mass percentage) is: Nb 35%, Sn 7%, Zr 8.5%, O 1%, with the balance being Ti.

[0033] Comparative Example 1 The difference between this comparative example and Example 1 is that in step one, the alloy ingot material composition (mass percentage) is: Nb 35%, Sn 7%, Zr 8.5%, with the balance being Ti.

[0034] Comparative Example 2 The difference between this comparative example and Example 1 is that in step one, the alloy ingot material composition (mass percentage) is: Nb 35%, Sn 7%, Zr 8.5%, O 1%, with the balance being Ti.

[0035] Comparative Example 3 The difference between this implementation method and Example 1 is that: (1) no oxygen element was added in step one; (2) no physical cryogenic cooling treatment was performed in step three.

[0036] Comparative Example 4 The difference between this embodiment and Example 1 is that: (1) no oxygen element was added in step one; and (2) no annealing treatment was performed in step six.

[0037] The tensile strength, elongation and elastic modulus of the intermediate products (solution alloys, cold-rolled sheets) and the final products prepared in Examples 1-4 and Comparative Examples 1-4 were tested, and the results are shown in Table 1.

[0038] Table 1 Test Results

[0039] Table 1 shows that by comparing the performance parameters of the cold-rolled sheets in Examples 1-4 with those of the final product, it was found that annealing the cold-rolled slab based on the coupling effect of magnetic field and heat can significantly improve the tensile strength and elongation of the titanium alloy sheet while maintaining a low elastic modulus. Examples 1-4 and Comparative Examples 1-2 show that adding an appropriate amount of oxygen can significantly improve the tensile strength and elongation of the titanium alloy sheet. Examples 1 and Comparative Example 3 show that when an appropriate amount of oxygen is added and physical cryogenic cooling is performed, the tensile strength of the titanium alloy sheet increases significantly, the elongation increases, and the elastic modulus decreases. Examples 1 and Comparative Example 4 show that when an appropriate amount of oxygen is added and annealing is performed, the tensile strength of the titanium alloy sheet increases significantly, the elongation increases, and the elastic modulus decreases. Therefore, the β-type titanium alloy designed in this invention, by adding an appropriate amount of O element and performing solid solution treatment, deep cryogenic treatment, rolling and annealing, produces titanium alloy plates with high tensile strength, elongation and low elastic modulus. In particular, when the alloy composition is Ti-35Nb-8.5Zr-7Sn-0.7O (Example 2), it exhibits even better strength and plasticity and low elastic modulus.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention in any way. All equivalent transformations or modifications made in accordance with the essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength, low-modulus β-type titanium alloy plate, characterized in that, The main steps include the following: Step 1: Weigh out pure titanium blocks, pure niobium blocks, pure tin blocks, pure zirconium blocks, and TiO2 particles. Stack the raw materials in a vacuum arc melting furnace from top to bottom in the order of pure niobium blocks, pure zirconium blocks, TiO2 particles, pure titanium blocks, and pure tin blocks. Repeatedly turn and melt 5-6 times to obtain an alloy ingot. The composition of the alloy ingot by mass percentage includes: Nb 35-40%, Sn 5-10%, Zr 8.5-10%, O 0.6-1%, and the remainder is Ti. Step 2: Place the alloy ingot in a tube furnace and heat it to 800~1000℃ under an argon atmosphere for solution treatment for 0.5~2 hours. After solution treatment, cool it to obtain a solution alloy. Step 3: Place the solid solution alloy in a beaker containing alcohol, add liquid nitrogen to keep the alcohol temperature at -30~-50℃, and perform physical cryogenic cooling. Step 4: Cut the solid solution alloy into several slabs and grind the slabs. Step 5: Perform multiple cold rolling processes on the slab, with a total rolling deformation of 80% to 90%. Step 6: Vacuum seal the cold-rolled slab and treat it at a temperature of 350-450℃ and a magnetic field of 1-15T for 0.5-2 hours to obtain a high-strength, low-modulus β-type titanium alloy plate.

2. The method for preparing a high-strength, low-modulus β-type titanium alloy plate according to claim 1, characterized in that, In step two, during the solution treatment, the gas pressure inside the tubular furnace should not exceed 0.02 MPa, and the argon atmosphere flow rate should be 10~30 sccm.

3. The method for preparing a high-strength, low-modulus β-type titanium alloy plate according to claim 1, characterized in that, In step two, after solution treatment, the solution is cooled by water quenching or ice-salt water quenching.

4. The method for preparing a high-strength, low-modulus β-type titanium alloy plate according to claim 1, characterized in that, In step four, the slab undergoes 8 to 12 cold rolling passes, with a single rolling deformation of 5 to 8%.

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