A high-strength and high-toughness titanium alloy and preparation method thereof

Abstract

The present invention discloses a high-strength and high-toughness titanium alloy, wherein the alloy composition of the high-strength and high-toughness titanium alloy is Ti6Al4VxNbyB, wherein 3≤x≤5, 0<y≤0.2, the microstructure of the high-strength and high-toughness titanium alloy is a near-lamellar or basket structure, and the initial β grain size of the high-strength and high-toughness titanium alloy is 143-1588μm. The high-strength and high-toughness titanium alloy has high tensile strength and toughness. The present invention also discloses a preparation method of the high-strength and high-toughness titanium alloy.

Description

Technical Field

[0001] The invention belongs to the field of metal alloys, and particularly relates to a high-strength and high-toughness titanium alloy and a preparation method thereof. Background Art

[0002] Titanium alloys have attracted extensive attention and research in the field of aerospace structural materials due to their high specific strength, fracture toughness and excellent oxidation resistance. Titanium alloys also have high damage tolerance and forging and casting properties. These outstanding advantages have led to the extensive use of titanium alloys in the aerospace industry, chemical industry, transportation and marine shipping industry.

[0003] TC4 (Ti-6Al-4V) is the most popular α+β duplex titanium alloy. It has low relative density and good corrosion resistance, fatigue resistance and biocompatibility. Therefore, it has been widely used in emerging fields such as aerospace, navigation, automobiles, medical equipment, sports equipment, etc. It is also one of the key materials for welded structural parts, load-bearing structural parts and large integral components. It is currently the most widely used titanium alloy. TC4 alloy has high strength, good thermal stability, excellent corrosion resistance, and good biocompatibility. It is known as the ace titanium alloy and has been used in many fields. It has also begun to be used as an oil pipe material.

[0004] The most commonly used method for producing titanium alloys is vacuum consumable arc melting, or VAR melting. In a vacuum state, a DC power supply is used to generate an arc between an electrode and the bottom plate of a copper crucible placed in a water jacket. The arc heating generates high heat, melting the electrode, and the electrode continues to descend and melt, forming a molten pool in a water-cooled copper crucible. The molten metal completes rapid solidification, crystallization, and solidification into an ingot. Vacuum arc melting is generally used to refine stainless steel, super alloys, titanium, zirconium, tantalum, niobium, tungsten, molybdenum and other easily oxidized metals and alloys, which reduces the loss of active elements (such as Al and Ti), and the ingot solidification process is controllable, which significantly improves the cleanliness, uniformity, fatigue resistance and fracture toughness of the ingot. Therefore, its organizational consistency and uniformity are good, the number of inclusions is small, and the purity of the alloy is further improved.

[0005] The advantages of vacuum consumable arc melting are mature technology, low cost, and the ability to achieve mass production of large-sized ingots. The vacuum consumable arc melting process is divided into three stages: the initial stage (arc starting period), the melting stage, and the hot capping (shrinkage compensation period). The main purpose of the initial stage is to stabilize the arc and establish a molten pool by gradually increasing the current and voltage; the melting stage is to carry out stable melting at a certain current and voltage to fully alloy and homogenize the raw materials; the hot capping period is to reduce shrinkage porosity and reduce the amount of head cutting by gradually reducing the current and voltage.

[0006] The inversion of strength and toughness has always been an important problem to be solved in the process of metal material performance development. How to achieve the simultaneous improvement of strength and toughness of metal alloys is the research focus of metal material modification. The mechanical properties of cast TC4 prepared by vacuum consumable arc melting technology are limited due to its coarse columnar crystals and internal full-lamellar microstructure.

[0007] Therefore, how to refine the size of as-cast TC4, regulate its microstructure, and optimize the mechanical properties through composition modification is the key issue currently faced. Summary of the invention

[0008] The invention provides a high-strength and high-toughness titanium alloy, which has high tensile strength and toughness.

[0009] The present invention provides a high-strength and high-toughness titanium alloy, wherein the alloy composition of the high-strength and high-toughness titanium alloy is Ti6Al4VxNbyB, wherein 3≤x≤5, 0<y≤0.2, the microstructure of the high-strength and high-toughness titanium alloy is a near-lamellar or basket structure, and the initial β grain size of the high-strength and high-toughness titanium alloy is 143-1588μm.

[0010] The present invention makes the microstructure of the titanium alloy into a near-lamellar or basket-net structure through a suitable Nb content, thereby effectively reducing the β-transformation temperature while improving the plasticity of the titanium alloy, thereby providing more nucleation sites. Based on more nucleation sites, TiB whiskers formed by the reaction of B element and Ti element can be uniformly grown in situ in the titanium alloy, and the grain refinement effect is better, thereby improving the strength of the titanium alloy; but in general, too high a B element content will form too much TiBet, thereby causing TiB aggregation, and further causing dislocation aggregation to undergo brittle changes and reduce strength, while the Nb element can effectively dissolve into the TiB whiskers, reduce the B2 phase, and improve the deformation resistance of the alloy, so that the strength is improved and the toughness is maintained when the B element content is high.

[0011] In the prior art, the content of B added to the alloy is generally between 0-0.2wt.%. As the B content increases, the toughness of the titanium alloy decreases significantly, but the strength increases significantly. The present invention overcomes the trend of rapid decrease in toughness and significantly improves the tensile strength by adding a suitable amount of Nb when the B content is relatively high, i.e., 0.2wt.%.

[0012] Furthermore, the Ti6Al4VxNbyB, wherein 3≤x≤4, 0.1<y≤0.2, the microstructure of the high-strength and high-toughness titanium alloy is nearly lamellar, and the initial β grain size of the high-strength and high-toughness titanium alloy is 143-357μm.

[0013] The present invention makes the microstructure of the titanium alloy near lamellar through the appropriate Nb content. The near-lamellar microstructure and the decrease of the β-transformation temperature can provide a suitable amount of nucleation sites combined with a suitable amount of B element, so that the formed TiB whiskers can be evenly distributed in the titanium alloy, with less aggregation, thereby having higher strength and toughness.

[0014] Furthermore, the tensile strength of the high-strength and high-toughness titanium alloy is 1000-1150 MPa, and the plastic deformation is 6.0-9.0%.

[0015] The present invention also provides a method for preparing the high-strength and high-toughness titanium alloy, comprising:

[0016] (1) mixing titanium sponge, Al beans, AlV alloy, Nb particles and B powder according to the composition ratio of the chemical formula of the high-strength and high-toughness titanium alloy to obtain a mixture;

[0017] (2) pressing the mixture into electrode blocks, and welding every two electrode blocks into smelting electrodes;

[0018] (3) The smelting electrode is subjected to a first vacuum consumable smelting to obtain a titanium alloy primary ingot, and the titanium alloy primary ingot is subjected to a second vacuum consumable smelting to obtain the high-strength and high-toughness titanium alloy.

[0019] Through the vacuum consumable arc melting process, a new type of high-strength and high-toughness titanium alloy is obtained after secondary remelting. With the increase of Nb particle content, the microstructure gradually changes from full lamellar to near lamellar and basketweave structure, realizing the improvement of mechanical properties. On the basis of adding Nb particles, after adding B powder, it reacts with the titanium matrix and TiB whiskers are synthesized in situ, the grains are further refined and the strength is improved.

[0020] Furthermore, the mass of the electrode block is 1-3 kg.

[0021] Furthermore, the smelting electrode is subjected to the first vacuum consumable smelting, and the process parameters of the first vacuum consumable smelting are: current of 1.2-1.8KA, voltage of 28-33V, pre-vacuum degree of 0-1Pa, and working vacuum degree of 0-8Pa.

[0022] The melting current determines the melting rate of Nb and B and the temperature of the molten pool, and has a direct impact on the shape, volume and depth of the molten pool. The melting voltage controls the arc length. If the arc length is too long, the arc heat energy is not concentrated, the heat loss of the molten pool is large, and it is easy to produce side arcs, which damage the crucible and cause accidents; if the arc length is too short, it is easy to produce periodic short circuits, causing the molten pool temperature to fluctuate frequently, affecting the uniformity of the ingot crystal structure.

[0023] Selecting a melting current of 1.2-1.8KA and a melting voltage of 28-33V can effectively control the melting rate, molten pool temperature and arc length of metal elements, which helps Nb and B elements to better dissolve into the Ti6Al4V matrix. At the same time, on the basis of adding a suitable content of Nb element to form a near-lamellar structure, it helps the B element to effectively combine with the titanium matrix evenly, avoid metal splashing during the melting process, and improve the surface quality of the ingot.

[0024] Furthermore, the diameter of the titanium alloy primary ingot is 60-100 mm.

[0025] Furthermore, the titanium alloy primary ingot is subjected to a second vacuum consumable smelting, and the process parameters of the second vacuum consumable smelting are: current of 2.9-3.6KA, voltage of 30-35V, pre-vacuum degree of 0-0.8Pa, and working vacuum degree of 0-5Pa.

[0026] In the secondary smelting, since the diameter of the smelting electrode increases after the first consumable smelting, the current should be appropriately increased. Through repeated consumable smelting, the gas and low-melting point harmful impurities in the metal can be further removed, non-metallic inclusions can be removed, and the degree of segregation can be reduced.

[0027] Furthermore, the diameter of the high-strength and high-toughness titanium alloy is 140-200 mm.

[0028] The new high-strength and high-toughness titanium alloy ingot obtained by secondary remelting through the vacuum consumable arc melting process provided in the embodiment of the present application achieves a simultaneous improvement in strength and plasticity of the new high-strength and high-toughness titanium alloy on the basis of TC4 by regulating the microstructure from full lamellar to near lamellar and basketweave structure, and adding reinforcing phase elements on the basis of near lamellar to refine the grains.

[0029] Since the initial β-phase grain boundaries formed at high temperatures in the new high-strength and high-toughness titanium alloy ingot obtained by secondary remelting through the vacuum consumable arc melting process provided in the embodiment of the present application will also be retained at room temperature, the embodiment of the present application describes the grain size based on the initial β-phase grain size formed by the initial β-phase grain boundaries. As the content of B powder in the mixed raw materials increases, the initial β-phase grain size shows a phenomenon of continuous decrease.

[0030] The present invention can significantly change the microstructure of the titanium alloy by gradually increasing the content of Nb particles, that is, changing from full lamellar to near lamellar, and then from near lamellar to basket structure, so as to obtain corresponding mechanical properties, that is, the elongation first increases and then decreases, thereby achieving precise control of the mechanical properties. B powder is added as a ceramic phase on the basis of the near lamellar structure, and the grain size can be controlled from 143 to 1588μm.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention adopts the method of adding Nb particles and B powder on the basis of the original TC4 (Ti-6Al-4V) alloy, and adds Nb particles as a β-phase stabilizing element, which effectively reduces the alloy β-phase transformation temperature, significantly adjusts the microstructure of the titanium alloy, and achieves significant changes in tensile strength and elongation; the addition of an appropriate content of Nb element forms a near-lamellar microstructure, provides more nucleation sites for the reaction of B element with the titanium matrix, generates TiB whiskers, and can detect the solid solution of Nb element in TiB whiskers, which not only significantly refines the titanium alloy grain size, but also can reduce the brittleness of TiB as a ceramic phase to a certain extent, effectively avoids the stress concentration caused by its segregation and aggregation, and improves the mechanical properties of the titanium alloy. The preparation method has universality and can be extended to the microstructure and mechanical property regulation of similar two-phase titanium alloys. The preparation process is mature, the production cycle is short, and the repeatability is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A secondary casting diagram of the high-strength and high-toughness titanium alloy prepared in Examples 1-5 and Comparative Example 1 of the present application;

[0034] Figure 2 The backscattered electron (BSE) microstructure diagram of the high-strength and high-toughness titanium alloy prepared in Examples 1-5 and Comparative Example 1 of the present application;

[0035] Figure 3 This is a diagram of the mechanical properties of the high-strength and high-toughness titanium alloys prepared in Examples 1-5 of the present application and Comparative Example 1. DETAILED DESCRIPTION

[0036] The following will provide a clear and complete description of the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0037] Example 1

[0038] Ti-6Al-4V-3Nb-0.1B is melted by vacuum consumable arc. The specific steps are as follows:

[0039] (1) Weighing materials: Weigh titanium sponge, Al beans, AlV alloy, Nb particles, and B powder according to the mass ratio of Ti 84.9%, Al 6%, V 4%, Nb 5%, and B 0.1%;

[0040] (2) Pressing the electrode: Press the raw materials mixed in proportion into electrode blocks. Each electrode block weighs 1 kg, and the raw materials are evenly mixed.

[0041] (3) Welding electrodes: Weld two pressed electrodes into a smelting electrode;

[0042] (4) Vacuum consumable arc melting of primary ingot: The welded melting electrode is placed in a vacuum consumable arc melting furnace for melting, with a current of 1.6KA, a voltage of 32V, a pre-vacuum degree ≤1Pa, a working vacuum degree ≤8Pa, and a copper crucible with a diameter of 100mm to melt a titanium alloy primary ingot with a diameter of 100mm;

[0043] (5) Vacuum consumable melting of secondary ingot: The obtained primary ingot is headed and tailed, and secondary melting is carried out in a vacuum consumable arc melting furnace with a current of 3.2KA, a voltage of 34V, a pre-vacuum degree ≤0.8Pa, a working vacuum degree ≤5Pa, and a copper crucible with a diameter of 140mm to melt a high-strength and high-toughness titanium alloy with a diameter of 140mm, namely TC4-4.

[0044] Example 2

[0045] Ti-6Al-4V-3Nb-0.2B is melted by vacuum consumable arc. The specific steps are as follows:

[0046] (1) Weighing materials: Weigh titanium sponge, Al beans, AlV alloy, Nb particles, and B powder according to the mass ratio of Ti 84.8%, Al 6%, V 4%, Nb 5%, and B 0.2%;

[0047] (2) Pressing the electrode: Press the raw materials mixed in proportion into electrode blocks. Each electrode block weighs 1 kg, and the raw materials are evenly mixed.

[0048] (3) Welding electrodes: Weld two pressed electrodes into a smelting electrode;

[0049] (4) Vacuum consumable melting of primary ingot: Place the welded melting electrode into a vacuum consumable arc melting furnace for melting, with a current of 1.6KA, a voltage of 32V, a pre-vacuum degree ≤1Pa, a working vacuum degree ≤8Pa, and a copper crucible with a diameter of 100mm to melt a titanium alloy primary ingot with a diameter of 100mm;

[0050] (5) Vacuum consumable melting of secondary ingot: The obtained primary ingot is headed and tailed, and secondary melting is carried out in a vacuum consumable arc melting furnace with a current of 3.2KA, a voltage of 34V, a pre-vacuum degree ≤0.8Pa, a working vacuum degree ≤5Pa, and a copper crucible with a diameter of 140mm to melt a high-strength and high-toughness titanium alloy with a diameter of 140mm, namely TC4-5.

[0051] Comparative Example 1

[0052] Ti-6Al-4V-1Nb is melted by vacuum consumable arc. The specific steps are as follows:

[0053] (1) Weighing materials: Weigh titanium sponge, Al beans, AlV alloy, and Nb particles and mix them in a mass ratio of Ti 89%, Al 6%, V 4%, and Nb 1%;

[0054] (2) Pressing the electrode: Press the raw materials mixed in proportion into electrode blocks. Each electrode block weighs 1 kg, and the raw materials are evenly mixed.

[0055] (3) Welding electrodes: Weld two pressed electrodes into a smelting electrode;

[0056] (4) Vacuum consumable melting of primary ingot: Place the welded melting electrode into a vacuum consumable arc melting furnace for melting, with a current of 1.6KA, a voltage of 32V, a pre-vacuum degree ≤1Pa, a working vacuum degree ≤8Pa, and a copper crucible with a diameter of 100mm to melt a titanium alloy primary ingot with a diameter of 100mm;

[0057] (5) Vacuum consumable melting of secondary ingot: The obtained primary ingot is headed and tailed, and secondary melting is carried out in a vacuum consumable arc melting furnace with a current of 3.2KA, a voltage of 34V, a pre-vacuum degree ≤0.8Pa, a working vacuum degree ≤5Pa, and a copper crucible with a diameter of 140mm to melt a titanium alloy secondary ingot with a diameter of 140mm, namely TC4-1.

[0058] Comparative Example 2

[0059] Ti-6Al-4V-3Nb is melted by vacuum consumable arc. The specific steps are as follows:

[0060] (1) Weighing materials: Weigh titanium sponge, Al beans, AlV alloy, and Nb particles and mix them in a mass ratio of Ti 87%, Al 6%, V 4%, and Nb 3%;

[0061] (2) Pressing the electrode: Press the raw materials mixed in proportion into electrode blocks. Each electrode block weighs 1 kg, and the raw materials are evenly mixed.

[0062] (3) Welding electrodes: Weld two pressed electrodes into a smelting electrode;

[0063] (4) Vacuum consumable melting of primary ingot: Place the welded melting electrode into a vacuum consumable arc melting furnace for melting, with a current of 1.7KA, a voltage of 32V, a pre-vacuum degree ≤1Pa, a working vacuum degree ≤8Pa, and a copper crucible with a diameter of 100mm to melt a titanium alloy primary ingot with a diameter of 100mm;

[0064] (5) Vacuum consumable melting of secondary ingot: The obtained primary ingot is headed and tailed, and secondary melting is carried out in a vacuum consumable arc melting furnace with a current of 3.2KA, a voltage of 34V, a pre-vacuum degree ≤0.8Pa, a working vacuum degree ≤5Pa, and a copper crucible with a diameter of 140mm to melt a titanium alloy secondary ingot with a diameter of 140mm, namely TC4-2.

[0065] Comparative Example 3

[0066] Ti-6Al-4V-5Nb is melted by vacuum consumable arc. The specific steps are as follows:

[0067] (1) Weighing materials: Weigh titanium sponge, Al beans, AlV alloy, and Nb particles and mix them in a mass ratio of Ti 85%, Al 6%, V 4%, and Nb 5%;

[0068] (2) Pressing the electrode: Press the raw materials mixed in proportion into electrode blocks. Each electrode block weighs 1 kg, and the raw materials are evenly mixed.

[0069] (3) Welding electrodes: Weld two pressed electrodes into a smelting electrode;

[0070] (4) Vacuum consumable melting of primary ingot: Place the welded melting electrode into a vacuum consumable arc melting furnace for melting, with a current of 1.6KA, a voltage of 32V, a pre-vacuum degree ≤1Pa, a working vacuum degree ≤8Pa, and a copper crucible with a diameter of 100mm to melt a titanium alloy primary ingot with a diameter of 100mm;

[0071] (5) Vacuum consumable melting of secondary ingot: The obtained primary ingot is headed and tailed, and secondary melting is carried out in a vacuum consumable arc melting furnace with a current of 3.3KA, a voltage of 34V, a pre-vacuum degree ≤0.8Pa, a working vacuum degree ≤5Pa, and a copper crucible with a diameter of 140mm to melt a titanium alloy secondary ingot with a diameter of 140mm, namely TC4-3.

[0072] Comparative Example 4

[0073] Compared with the implementation, the difference is that no Nb particles and B powder are added, and the obtained titanium alloy is TC4.

[0074] Performance comparison:

[0075] See also Figure 1 , Figure 1 The actual pictures of the secondary ingots after two vacuum consumable arc melting of comparative examples 1-4 and examples 1-2 are shown. TC4, TC4-1, TC4-2, TC4-3, TC4-4, TC4-5 correspond to comparative examples 4, 1, 2, 3 and examples 1, 2 respectively. It can be seen from the figure that the secondary ingots obtained by melting have no obvious pores and defects on the surface.

[0076] See also Figure 2 , Figure 2 The tissue morphology diagrams of Comparative Examples 1-4 and Examples 1-2 are shown, wherein: Figure 2 (a) and Figure 2 (e) is the structure, size and morphology of the titanium alloy prepared in Comparative Example 4. Figure 2 (b) is the microstructure of the titanium alloy prepared in Comparative Example 1. Figure 2 (c) is the microstructure of the titanium alloy prepared in Comparative Example 2. Figure 2 (d) is the microstructure of the titanium alloy prepared in Comparative Example 3. Figure 2 (f) is the size morphology diagram of the titanium alloy prepared in Example 1, Figure 2 (g) is the size morphology of the titanium alloy prepared in Example 2. Figure 2 As shown in (a) to (d), with the increase of Nb particle addition, the microstructure gradually changes from full lamellar to near lamellar, and finally forms a basket-like structure; Figure 2 As shown in (e), (f) and (g), based on the addition of 3wt.% Nb particles, the grain size decreases significantly with the increase of B powder addition. Statistics show that the size of the initial β grains is refined from 1588μm to 143μm, which indicates that the addition of B powder can effectively refine the grain size of titanium alloy.

[0077] See also Figure 3 , Figure 3 The tensile strength curves of Comparative Examples 1-4 and Examples 1-2 are shown. Among them, the curve corresponding to TC4 is the tensile strength curve of Comparative Example 4;

[0078] The curve corresponding to TC4-1 is the tensile strength curve of Comparative Example 1;

[0079] The curve corresponding to TC4-2 is the tensile strength curve of Comparative Example 2;

[0080] The curve corresponding to TC4-3 is the tensile strength curve of Comparative Example 3;

[0081] The curve corresponding to TC4-4 is the tensile strength curve of Example 1;

[0082] The curve corresponding to TC4-5 is the tensile strength curve of Example 2.

[0083] like Figure 3As shown in the figure, with the increase of Nb particle addition, the tensile strength of titanium alloy increases, and the elongation shows a trend of first increasing and then decreasing. This is mainly because Nb, as a β-phase stabilizing element, solid-dissolves into β-Ti, effectively improving the strength and plasticity of the material. With the appropriate addition, the strength and plasticity of titanium alloy are better matched, and the elongation of the material is maintained at a high level while the strength is significantly improved.

[0084] In the 3 to 5wt.% addition stage, the elongation of titanium alloy decreases. This is mainly due to the addition of excessive Nb particles, which increases the β phase content in the titanium alloy matrix while strengthening the β phase in the initial β grains, resulting in differences in mechanical properties between the interior of the grains and the grain boundaries: during tensile loading, dislocations inside the β grains can pass smoothly, but they gather and entangle at the grain boundaries, resulting in stress concentration at the grain boundaries, which become the initiation point of cracks and cause a decrease in elongation.

[0085] On the basis of adding 3wt.% Nb particles, with the addition of B powder, the original continuous large eutectic phase between dendrites is suppressed by fine dendrites and divided into discontinuous eutectic phase, the grain size is continuously reduced, fine grain strengthening is achieved, and the strength of titanium alloy is significantly improved; due to the solid solution effect of Nb element on boride, the brittleness of TiB whiskers is suppressed, the deformation resistance of titanium alloy is effectively improved, and the plasticity of titanium alloy is maintained while the strength is improved, showing Figure 3 The tensile properties change curve shown.

Claims

1. A high-strength and high-toughness titanium alloy, It is characterized in that The alloy composition of the high-strength and high-toughness titanium alloy is Ti6Al4VxNbyB in terms of mass percentage, wherein 3≤x≤5, 0<y≤0.2, the microstructure of the high-strength and high-toughness titanium alloy is a near-lamellar or basket structure, and the initial β grain size of the high-strength and high-toughness titanium alloy is 143~357 μm.

2. The high-strength and high-toughness titanium alloy according to claim 1, It is characterized in that The Ti6Al4VxNbyB, wherein 3≤x≤4, 0.1<y≤0.2, the microstructure of the high-strength and high-toughness titanium alloy is nearly lamellar.

3. The high-strength and high-toughness titanium alloy according to claim 1, It is characterized in that The high-strength and high-toughness titanium alloy has a tensile strength of 1000-1150 MPa and a plastic deformation of 6.0-9.0%.

4. A method for preparing a high-strength and high-toughness titanium alloy as claimed in any one of claims 1 to 3, It is characterized in that include: (1) mixing titanium sponge, Al beans, AlV alloy, Nb particles and B powder according to the alloy component ratio of the high-strength and high-toughness titanium alloy to obtain a mixture; (2) pressing the mixture into electrode blocks, and welding every two electrode blocks into a smelting electrode; (3) The smelting electrode is subjected to a first vacuum consumable smelting to obtain a titanium alloy primary ingot, and the titanium alloy primary ingot is subjected to a second vacuum consumable smelting to obtain the high-strength and high-toughness titanium alloy.

5. The method for preparing the high-strength and high-toughness titanium alloy according to claim 4, It is characterized in that The mass of the electrode block is 1-3 kg.

6. The method for preparing the high-strength and high-toughness titanium alloy according to claim 4, It is characterized in that The process parameters of the first vacuum consumable smelting are: current of 1.2-1.8KA, voltage of 28-33V, pre-vacuum degree of 0-1Pa, and working vacuum degree of 0-8Pa.

7. The method for preparing the high-strength and high-toughness titanium alloy according to claim 4, It is characterized in that The diameter of the titanium alloy primary ingot is 60-100 mm.

8. The method for preparing the high-strength and high-toughness titanium alloy according to claim 4, It is characterized in that The process parameters of the second vacuum consumable melting are: current of 2.9-3.6KA, voltage of 30-35V, pre-vacuum degree of 0-0.8Pa, and working vacuum degree of 0-5Pa.

9. The method for preparing the high-strength and high-toughness titanium alloy according to claim 4, It is characterized in that The diameter of the high-strength and high-toughness titanium alloy is 140-200 mm.

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