High-strength titanium alloy and forging method thereof

Abstract

The invention relates to the technical field of metal material machining, and provides a high-strength titanium alloy and a forging method thereof.The forging method of the high-strength titanium alloy comprises the steps that vacuum consumable smelting is conducted on a titanium alloy raw material to obtain a titanium alloy cast ingot, and the titanium alloy cast ingot is pretreated to obtain a first titanium alloy cast ingot; and the first titanium alloy cast ingot is sequentially subjected to cogging forging, intermediate billet forging, octagonal drawing-out forging and round bar drawing-out forging and then is air-cooled to the room temperature, and the high-strength titanium alloy is obtained. According to the high-strength titanium alloy and the forging method thereof, the high-strength titanium alloy is developed through optimization and adjustment on the basis of TA15 alloy components, and a high-strength titanium alloy large-size round bar with the diameter specification of 300-400 mm is obtained through the forging method matched with the high-strength titanium alloy.

Description

Technical Field

[0001] The invention relates to the technical field of metal material processing, and in particular to a high-strength titanium alloy and a forging method thereof. Background Art

[0002] Titanium alloys are widely used in aerospace, medical equipment, chemical industry and other fields due to their excellent properties such as low density, high strength and corrosion resistance. At present, the blanking process of large titanium and titanium alloy ingots is generally to form a forging blank through multi-fire blanking forging. The forging blanking process includes a multi-fire multi-pass forging process, combining hot die forging and cold die forging technology. First, hot die forging is carried out to use the good plasticity at high temperature to preliminarily process the blank into the required shape; then cold die forging is carried out to improve the density and mechanical properties of titanium alloys.

[0003] Among the near-α-type titanium alloys, TA15 alloy is a medium-strength titanium alloy of the Ti-Al-Zr-Mo-V series. It has good welding performance and plasticity, and excellent comprehensive performance. It is mainly used as titanium alloy for aircraft frames. With the development trend of lightweight aircraft, the strength and plasticity of TA15 series titanium alloys have room for further improvement.

[0004] Due to the limitations of equipment capacity and forging technology, the traditional titanium alloy forging process has poor uniformity of forging blank microstructure and performance, and there are problems such as unstable core and surface properties of the material, which cannot meet the subsequent processing and use requirements of the material.

[0005] CN 118406933 A discloses a Ti-Al-Zr-Mo-V series high-strength titanium alloy and a preparation method thereof. The titanium alloy raw materials are mixed and welded into consumable electrodes, and an ingot is obtained after three vacuum consumable smelting. The ingot is subjected to blank forging, intermediate blank forging, rounding forging and heat treatment to obtain a Ti-Al-Zr-Mo-V series high-strength titanium alloy; wherein the Ti-Al-Zr-Mo-V series high-strength titanium alloy comprises, by weight percentage, Al: 6.1% to 7.1%, Mo: 2.0% to 4.0%, V: 2.5% to 3.9%, Zr: 2.0% to 3.0%, and the remainder is Ti and unavoidable impurities. The titanium alloy has a tensile strength of 1000 to 1230 MPa, an average shrinkage of ≥30%, an improved strength of the titanium alloy, and no significant reduction in plasticity. The prior art adopts a deformation method combining reversing upsetting and rounding, so that the deformation uniformity of each position of the blank is improved. However, the prior art does not improve the uniformity of the structure and performance of the core and surface of the round rod.

[0006] CN 106947887 A discloses a novel high-temperature titanium alloy composition design and multi-directional forging process, which is made of mass fractions of Al: 6.5-7.5%, Sn: 2-3%, Zr: 6-9%, Mo: 0.2-1%, W: 0.5-1.4%, Nb: 0.5-1.5%, Si: 0.2-0.3%, Er: 0.1-0.3% and the balance is Ti. The forging process of the high-temperature titanium alloy in the prior art is multi-directional die forging, and the tensile strength of the manufactured high-temperature titanium alloy forging blank is 615MPa at 650°C and the elongation is 47%. However, the prior art does not improve the uniformity of the core and surface structure and performance of the round bar.

[0007] CN 109865788 A discloses a high-efficiency upsetting and drawing forging method for large-size titanium alloy forging blanks. When upsetting, upper and lower flat anvils are used for forging, and the width w1 of the upper and lower anvils and the side length a of the blank before upsetting should satisfy 2.5≤w1 / a≤3.5; after upsetting, the blank is quickly turned 90°, and upper and lower flat anvils and left and right flat anvils are used for drawing and forging at the same time, wherein the width w2 of the left and right anvils and the side length a of the blank before upsetting should satisfy 1.5≤w2 / a≤2.4, and the length h2 of the left and right anvils should be consistent with the width w1 of the upper and lower anvils. During drawing and drawing, the pressing amount of the upper and lower anvils and the left and right anvils in the same pass is consistent, and the blank is rotated 45° after each pass. The prior art uses upper and lower flat anvils to forge an ingot into an octagonal blank and upsets it, uses upper and lower flat anvils and left and right flat anvils to draw and forge at the same time, and uses the upper flat and lower V method to draw and roll the blank to a finished product, and the uniformity of the finished bar structure is significantly improved. However, the prior art does not improve the uniformity of the structure and performance of the core and surface of the round rod.

[0008] Based on this, there is room for improvement in improving the uniformity of the core and surface structure and properties of titanium alloy round bars. Summary of the invention

[0009] In view of this, the present invention provides a high-strength titanium alloy and a forging method thereof, which solves the problems of poor uniformity of forging blank microstructure and performance and unstable core and surface properties of the material in the traditional titanium alloy forging process.

[0010] In order to solve the above technical problems, an embodiment of the present invention provides a forging method of a high-strength titanium alloy, comprising: performing vacuum consumable smelting on a titanium alloy raw material to obtain a titanium alloy ingot, pre-treating the titanium alloy ingot to obtain a first titanium alloy ingot, and sequentially performing blank forging, intermediate blank forging, eight-way drawing forging, and round bar drawing forging on the first titanium alloy ingot, followed by air cooling to room temperature to obtain a high-strength titanium alloy; The first titanium alloy ingot is subjected to blank forging, comprising: heating the first titanium alloy ingot to a first temperature and keeping the temperature for a first time, and then performing two-pass multi-directional forging on the first titanium alloy ingot to obtain a titanium alloy intermediate blank; The round bar drawing forging of the first titanium alloy ingot includes: using a curved anvil and a forging process matched with the curved anvil to draw the titanium alloy forging material after the eight-way drawing forging in multiple fires and multiple passes. In some embodiments, pre-processing the titanium alloy ingot to obtain a first titanium alloy ingot includes: cutting off the riser end of the titanium alloy ingot, removing surface defects and oxide scale of the remaining ingot of the titanium alloy ingot, and cutting the remaining ingot of the titanium alloy ingot along the height direction of the remaining ingot of the titanium alloy ingot to obtain the first titanium alloy ingot.

[0011] In some embodiments, performing two-fire multi-pass multi-directional forging on a first titanium alloy ingot includes: performing a first-fire multi-pass multi-directional forging on the first titanium alloy ingot to obtain a second titanium alloy intermediate billet, heating the second titanium alloy intermediate billet to a second temperature, and then performing a second-fire multi-pass multi-directional forging on the second titanium alloy intermediate billet.

[0012] In some embodiments, performing a first-fire multi-pass multi-directional forging on a first titanium alloy ingot to obtain a second titanium alloy intermediate billet includes the following steps: Step 1, fully anvil pressing the first titanium alloy ingot along a first horizontal direction of the first titanium alloy ingot according to a first pass pressing amount, and then fully anvil pressing the first titanium alloy ingot along a second horizontal direction of the first titanium alloy ingot at 90° to the first horizontal direction of the first titanium alloy ingot according to a second pass pressing amount; Step 2: Repeat step 1. Step 3, forging the first titanium alloy ingot along the vertical direction according to the third reduction amount to obtain a first titanium alloy intermediate billet; Step 4, obtain the second titanium alloy intermediate billet in the following manner: forge the first titanium alloy intermediate billet in sequence by pressing down the first horizontal direction of the first titanium alloy intermediate billet for the fourth time, pressing down the second horizontal direction of the first titanium alloy intermediate billet at an angle of 90° to the first horizontal direction of the first titanium alloy intermediate billet for the fifth time, and pressing down the vertical direction for the sixth time.

[0013] In some embodiments, performing multi-directional forging of the second titanium alloy intermediate billet with a second fire multiple passes includes: performing 1 to 2 passes of multi-directional forging, each pass of multi-directional forging is to forge the second titanium alloy intermediate billet in sequence along the first horizontal direction of the second titanium alloy intermediate billet according to the seventh pass reduction, along the second horizontal direction of the second titanium alloy intermediate billet at 90° to the first horizontal direction of the second titanium alloy intermediate billet according to the eighth pass reduction, and along the vertical direction according to the ninth pass reduction.

[0014] In some embodiments, forging the first titanium alloy ingot into an intermediate billet includes: heating the titanium alloy intermediate billet to a fourth temperature and keeping it warm for a third time, and then performing multi-fire and multi-directional forging on the titanium alloy intermediate billet to obtain a titanium alloy octagonal billet.

[0015] In some embodiments, the titanium alloy intermediate billet is subjected to multi-directional forging with multiple fires, including: performing multi-directional forging on the titanium alloy intermediate billet for 5 to 6 fires, wherein each fire of multi-directional forging includes 1 to 2 passes of multi-directional forging, and each pass of multi-directional forging is forging the titanium alloy intermediate billet in sequence along a first horizontal direction of the titanium alloy intermediate billet according to the tenth pass reduction, along a second horizontal direction of the titanium alloy intermediate billet at 90° to the first horizontal direction of the titanium alloy intermediate billet according to the eleventh pass reduction, and along the vertical direction according to the twelfth pass reduction.

[0016] In some embodiments, performing octagonal stretch forging on the first titanium alloy ingot includes: heating the titanium alloy octagonal billet to a sixth temperature and keeping it at a fourth time, and then performing octagonal stretch forging on the titanium alloy octagonal billet once to obtain a titanium alloy forging.

[0017] In some embodiments, a forging process matching with an arc anvil is used to perform multi-pass and multi-fire stretching on the titanium alloy forging after eight-way stretching forging, including: first, two identical arc anvils are arranged symmetrically up and down; second, the titanium alloy forging is heated to a seventh temperature and kept warm for a fifth time, and then the titanium alloy forging is stretched for 1 to 2 times in multiple passes. During each multi-pass stretching process, the titanium alloy forging is stretched with the seventeenth pass reduction in each stretching pass. The feed amount of the titanium alloy forging is 450 mm to 600 mm. After each stretching pass, the titanium alloy forging is rotated 90° around the axis before the next stretching pass.

[0018] An embodiment of the present invention provides a high-strength titanium alloy, which is manufactured by the forging method of the high-strength titanium alloy. The chemical composition of the high-strength titanium alloy is calculated by element mass percentage: Al: 5% to 6.5%, Mo: 1.5% to 3%, V: 1.5% to 2%, Zr: 3% to 4%, Sn: 2.5% to 3.6%, Nb: 0.5% to 1.5%, Si: 0.2% to 0.5%; the remainder is Ti and other unavoidable impurity elements.

[0019] Through the above technical scheme, the high-strength titanium alloy and its forging method provided by the present invention are developed through optimization and adjustment on the basis of the TA15 alloy composition, and a high-strength titanium alloy is developed. By adopting a forging method matching it, that is, a "multi-directional forging" with multiple fires and multiple passes followed by a forging method using upper and lower anvils of a specific shape for stretching, a high-strength titanium alloy large-size round bar with a diameter of 300mm to 400mm is obtained, which can be promoted to similar products or enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of the forging direction of the forging method of the high-strength titanium alloy of the present invention; Figure 2 A side view of a curved anvil for implementing the forging method of the high-strength titanium alloy of the present invention; Figure 3 A front view of a curved anvil for implementing the forging method of the high-strength titanium alloy of the present invention; Figure 4 The microstructure of the core of a round rod of a high-strength titanium alloy prepared by the forging method of a high-strength titanium alloy in Example 1 of the present invention; Figure 5 The core microstructure of a round rod of high-strength titanium alloy prepared by the forging method of high-strength titanium alloy in Example 2 of the present invention. DETAILED DESCRIPTION

[0022] The following is a further detailed description of the embodiments of the present invention in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to exemplarily illustrate the principles of the present invention, but cannot be used to limit the scope of the present invention. The present invention can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0023] It should be noted that all the "first", "second" and similar words used in the embodiments of the present invention do not indicate any order, quantity or importance. The expressions of "first" and "second" are intended to distinguish two entities with the same name but not the same or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one. "Include" or "comprising" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of also including other elements.

[0024] It should be noted that, in the description of the present invention, unless otherwise specified, the meaning of "multiple" is greater than or equal to two; the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicating the orientation or positional relationship, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0025] The forging method of high-strength titanium alloy provided by the present invention comprises: performing vacuum consumable smelting on titanium alloy raw material to obtain titanium alloy ingot, pretreating the titanium alloy ingot to obtain a first titanium alloy ingot, and sequentially performing blank forging, intermediate blank forging, eight-way drawing forging and round rod drawing forging on the first titanium alloy ingot and then air cooling to room temperature to obtain the high-strength titanium alloy.

[0026] In some embodiments, the forging method of high-strength titanium alloy includes: mixing raw materials prepared according to chemical composition ratios, pressing electrode blocks, and vacuum plasma welding to form electrodes, where the electrodes are titanium alloy raw materials.

[0027] In some embodiments, the chemical composition ratio is calculated by element mass percentage as follows: Al: 5% to 6.5%, Mo: 1.5% to 3%, V: 1.5% to 2%, Zr: 3% to 4%, Sn: 2.5% to 3.6%, Nb: 0.5% to 1.5%, Si: 0.2% to 0.5%; the remainder is Ti and other unavoidable impurity elements.

[0028] In some embodiments, the raw materials include sponge titanium, baked TiO2 powder, vanadium aluminum alloy, aluminum molybdenum, sponge zirconium, and a master alloy containing tin and niobium. For example, the raw materials sponge titanium, baked TiO2 powder, vanadium aluminum alloy, aluminum molybdenum, sponge zirconium, and a master alloy containing tin and niobium are weighed and mixed according to the chemical composition ratio of the high-strength titanium alloy.

[0029] In some embodiments, the titanium alloy raw material is subjected to vacuum consumable smelting three times to obtain a titanium alloy ingot.

[0030] In some embodiments, the titanium alloy ingot is a 6-ton titanium alloy ingot with a diameter Φ of 860 mm and a length of 1900 mm to 2000 mm.

[0031] In some embodiments, pre-treating the titanium alloy ingot to obtain the first titanium alloy ingot includes: cutting off the riser end of the titanium alloy ingot, removing surface defects and oxide scale of the remaining ingot of the titanium alloy ingot, and cutting the remaining ingot of the titanium alloy ingot along the height direction of the remaining ingot of the titanium alloy ingot to obtain the first titanium alloy ingot. The pre-treating can ensure the quality of the first titanium alloy ingot.

[0032] The riser end refers to the part where the riser is connected to the casting or the end area where the riser is located on the casting. The riser end should generally be set at the part of the casting that solidifies last, such as the top of the thick part, the corner, etc., so that the liquid metal can naturally flow into the casting under the action of gravity for shrinkage compensation. Titanium alloy ingots are usually placed vertically during casting, with the riser located at the top of the ingot, and the riser end is the part where the ingot and the riser are directly connected. The riser end is at the top of the titanium alloy ingot. The shape of the riser end is generally compatible with the shape of the riser, and common ones are round and rectangular.

[0033] In some embodiments, the first titanium alloy ingot has a height of 380 mm to 400 mm.

[0034] In some embodiments, the blank forging of the first titanium alloy ingot includes: heating the first titanium alloy ingot to a first temperature and keeping the temperature for a first time, and then performing multi-directional forging of the first titanium alloy ingot in two passes to obtain a titanium alloy intermediate billet.

[0035] In some embodiments, heating the first titanium alloy ingot to a first temperature and keeping it warm for a first time includes: placing the first titanium alloy ingot in a resistance furnace, heating it to a first temperature and keeping it warm for a first time, wherein the first temperature is 90° C. to 200° C. higher than the phase transition point. For example, the phase transition point is the temperature at which the α-phase titanium alloy with a close-packed hexagonal structure and the β-phase titanium alloy with a body-centered cubic structure transform into each other, including the heating phase transition point of the α→β transformation and the cooling phase transition point of the β→α transformation.

[0036] In some embodiments, the first temperature is 1040° C. to 1150° C., and the first time is 4 h to 6 h.

[0037] In some embodiments, performing two-fire multi-pass multi-directional forging on a first titanium alloy ingot includes: performing a first-fire multi-pass multi-directional forging on the first titanium alloy ingot to obtain a second titanium alloy intermediate billet, heating the second titanium alloy intermediate billet to a second temperature, and then performing a second-fire multi-pass multi-directional forging on the second titanium alloy intermediate billet.

[0038] In titanium alloy processing, two passes refer to the process in which titanium alloy ingots or billets need to undergo two heating forging or processing. The purpose is to effectively improve the organizational structure of titanium alloy through multiple heating forging, making it more dense and uniform, improving the comprehensive performance of the material, and also facilitating subsequent processing and forming. Multiple passes refer to the process in which titanium alloy undergoes multiple deformation processes, such as multiple rolling and forging operations, in each pass. The purpose is that as the number of passes increases, the microstructure inside the titanium alloy will undergo dynamic recovery, recrystallization and other changes, so that the grains are refined and the dislocation density is reduced, thereby improving the strength, toughness and other properties of the material.

[0039] In some embodiments, performing a first-fire multi-pass multi-directional forging on a first titanium alloy ingot to obtain a second titanium alloy intermediate billet includes the following steps: Step 1, fully anvil pressing the first titanium alloy ingot along a first horizontal direction of the first titanium alloy ingot according to a first pass pressing amount, and then fully anvil pressing the first titanium alloy ingot along a second horizontal direction of the first titanium alloy ingot at 90° to the first horizontal direction of the first titanium alloy ingot according to a second pass pressing amount; Step 2: Repeat step 1. Step 3, forging the first titanium alloy ingot along the vertical direction according to the third reduction amount to obtain a first titanium alloy intermediate billet; Step 4, obtain the second titanium alloy intermediate billet in the following manner: forge the first titanium alloy intermediate billet in sequence by pressing down the first horizontal direction of the first titanium alloy intermediate billet for the fourth time, pressing down the second horizontal direction of the first titanium alloy intermediate billet at an angle of 90° to the first horizontal direction of the first titanium alloy intermediate billet for the fifth time, and pressing down the vertical direction for the sixth time.

[0040] Before the first multi-pass multi-directional forging, the first horizontal direction of the first titanium alloy ingot, the second horizontal direction of the first titanium alloy ingot, and the vertical direction correspond to Figure 1 The x-axis direction, y-axis direction and z-axis direction in the spatial rectangular coordinate system shown.

[0041] In some embodiments, the first horizontal direction of the first titanium alloy ingot is the first diameter direction of the first titanium alloy ingot, the second horizontal direction of the first titanium alloy ingot is the second diameter direction of the first titanium alloy ingot, and the vertical direction is the height direction of the first titanium alloy ingot, wherein the first diameter direction of the first titanium alloy ingot is perpendicular to the second diameter direction of the first titanium alloy ingot, and the height direction of the first titanium alloy ingot is perpendicular to the first diameter direction of the first titanium alloy ingot and the second diameter direction of the first titanium alloy ingot, respectively. In step 1, the first titanium alloy ingot can be rotated 90° around an axis (the axis direction is parallel to the z-axis direction) so that the second diameter direction of the first titanium alloy ingot is rotated to Figure 1 The x-axis direction is shown.

[0042] In some embodiments, the first horizontal direction of the first titanium alloy intermediate billet, the second horizontal direction and the vertical direction of the first titanium alloy intermediate billet correspond to Figure 1The x-axis direction, y-axis direction and z-axis direction in the spatial rectangular coordinate system shown in the figure are perpendicular to the height direction of the first titanium alloy intermediate billet, wherein the first horizontal direction of the first titanium alloy intermediate billet is perpendicular to the second horizontal direction of the first titanium alloy intermediate billet, and the height direction of the first titanium alloy intermediate billet is perpendicular to the first horizontal direction of the first titanium alloy intermediate billet and the second horizontal direction of the first titanium alloy intermediate billet. In step 4, the first titanium alloy intermediate billet can be rotated 90° around an axis (the axis direction is parallel to the z-axis direction) so that the second horizontal direction of the first titanium alloy intermediate billet is rotated to Figure 1 The x-axis direction is shown.

[0043] In the field of metal processing, especially titanium alloy processing, full anvil pressing is a forging operation method, which refers to the operation of using the anvil to completely cover the surface of the workpiece to be processed during the forging process, and then applying pressure to cause the workpiece to undergo plastic deformation. Full anvil pressing has the effect of uniform deformation, improved organization, and increased material utilization.

[0044] Forging is a processing method that utilizes the plasticity of metal materials to plastically deform metal blanks by applying pressure, thereby obtaining blanks or parts with certain shapes, sizes and mechanical properties. The basic principles of forging include plastic deformation and recrystallization of metals.

[0045] In some embodiments, in step 1, the first pressing amount is 75 mm to 85 mm, and the second pressing amount is 75 mm to 85 mm.

[0046] In some embodiments, in step 3, the third pressing amount is 35 mm to 45 mm.

[0047] In some embodiments, in step 4, the fourth pass pressing amount is 40 mm to 80 mm, the fifth pass pressing amount is 40 mm to 80 mm, and the sixth pass pressing amount is 40 mm to 80 mm.

[0048] In some embodiments, performing the first-pass multi-directional forging of the first titanium alloy ingot includes maintaining the final forging temperature at a third temperature, for example, the third temperature is greater than or equal to 850°C.

[0049] In some embodiments, heating the second titanium alloy intermediate billet to a second temperature includes: placing the second titanium alloy intermediate billet in a resistance furnace, heating it to the second temperature, and keeping the temperature for a second time.

[0050] In some embodiments, the second temperature is 1000° C. to 1100° C., and the second time is 4 h to 6 h.

[0051] In some embodiments, performing multi-directional forging of the second titanium alloy intermediate billet with a second fire multiple passes includes: performing 1 to 2 passes of multi-directional forging, each pass of multi-directional forging is to forge the second titanium alloy intermediate billet in sequence along the first horizontal direction of the second titanium alloy intermediate billet according to the seventh pass reduction, along the second horizontal direction of the second titanium alloy intermediate billet at 90° to the first horizontal direction of the second titanium alloy intermediate billet according to the eighth pass reduction, and along the vertical direction according to the ninth pass reduction.

[0052] In some embodiments, the first horizontal direction of the second titanium alloy intermediate billet, the second horizontal direction of the second titanium alloy intermediate billet, and the vertical direction correspond to Figure 1 The x-axis direction, y-axis direction and z-axis direction in the spatial rectangular coordinate system shown in the figure are perpendicular to the height direction of the second titanium alloy intermediate billet, wherein the first horizontal direction of the second titanium alloy intermediate billet is perpendicular to the second horizontal direction of the second titanium alloy intermediate billet, and the height direction of the second titanium alloy intermediate billet is perpendicular to the first horizontal direction of the second titanium alloy intermediate billet and the second horizontal direction of the second titanium alloy intermediate billet. The second titanium alloy intermediate billet can be rotated 90° around an axis (the axis direction is parallel to the z-axis direction) so that the second horizontal direction of the second titanium alloy intermediate billet is rotated to Figure 1 The x-axis direction is shown.

[0053] In some embodiments, the seventh pass has a pressing reduction of 40 mm to 80 mm, the eighth pass has a pressing reduction of 40 mm to 80 mm, and the ninth pass has a pressing reduction of 40 mm to 80 mm.

[0054] In some embodiments, the titanium alloy intermediate billet is in the shape of a cube, for example, the titanium alloy intermediate billet is in the shape of a cube with a side length of 600 mm to 610 mm.

[0055] The advantages of forging the first titanium alloy ingot are as follows: forging at a temperature above the phase transformation point is conducive to fully crushing the coarse β grains in the first titanium alloy ingot, and multi-directional forging with two fires and multiple passes is conducive to increasing the total deformation of the first titanium alloy ingot, accumulating deformation energy, and facilitating subsequent phase transformation combined with recrystallization to refine the grains.

[0056] In some embodiments, forging the first titanium alloy ingot into an intermediate billet includes: heating the titanium alloy intermediate billet to a fourth temperature and keeping it warm for a third time, and then performing multi-fire and multi-directional forging on the titanium alloy intermediate billet to obtain a titanium alloy octagonal billet.

[0057] In some embodiments, the titanium alloy intermediate billet is subjected to multi-directional forging with multiple fires, including: performing multi-directional forging on the titanium alloy intermediate billet for 5 to 6 fires, wherein each fire of multi-directional forging includes 1 to 2 passes of multi-directional forging, and each pass of multi-directional forging is forging the titanium alloy intermediate billet in sequence along a first horizontal direction of the titanium alloy intermediate billet according to the tenth pass reduction, along a second horizontal direction of the titanium alloy intermediate billet at 90° to the first horizontal direction of the titanium alloy intermediate billet according to the eleventh pass reduction, and along the vertical direction according to the twelfth pass reduction.

[0058] In some embodiments, the tenth pass has a pressing reduction of 200 mm to 300 mm, the eleventh pass has a pressing reduction of 200 mm to 300 mm, and the twelfth pass has a pressing reduction of 200 mm to 300 mm.

[0059] In some embodiments, the final forging temperature of each multi-directional forging is the fifth temperature, and the titanium alloy intermediate billet after each multi-directional forging maintains a cube shape, and the side length of the cube is 600 mm to 610 mm.

[0060] In some embodiments, the fourth temperature is 900°C to 1100°C, the third time is 4 hours to 5 hours, and the fifth temperature is greater than or equal to 750°C.

[0061] In some embodiments, the first horizontal direction of the titanium alloy intermediate billet, the second horizontal direction of the titanium alloy intermediate billet, and the vertical direction correspond to Figure 1 The x-axis direction, y-axis direction and z-axis direction in the spatial rectangular coordinate system shown in the figure are perpendicular to the height direction of the titanium alloy intermediate billet, wherein the first horizontal direction of the titanium alloy intermediate billet is perpendicular to the second horizontal direction of the titanium alloy intermediate billet, and the height direction of the titanium alloy intermediate billet is perpendicular to the first horizontal direction of the titanium alloy intermediate billet and the second horizontal direction of the titanium alloy intermediate billet. The titanium alloy intermediate billet can be rotated 90° around an axis (the axis direction is parallel to the z-axis direction) so that the second horizontal direction of the titanium alloy intermediate billet is rotated to Figure 1 The x-axis direction is shown.

[0062] In some embodiments, in each multi-directional forging, the titanium alloy intermediate billet has a first deformation amount in the first horizontal direction, a second deformation amount in the second horizontal direction, and a third deformation amount in the height direction of the titanium alloy intermediate billet. For example, the first deformation amount is 25% to 45%, the second deformation amount is 25% to 45%, and the third deformation amount is 25% to 45%.

[0063] When the first titanium alloy ingot is forged into an intermediate billet, the forging temperature is appropriately lowered. After multiple times of multi-directional forging, the coarse β grains can be continuously broken to improve the uniformity of the structure.

[0064] In some embodiments, performing octagonal stretch forging on the first titanium alloy ingot includes: heating the titanium alloy octagonal billet to a sixth temperature and keeping it at a fourth time, and then performing octagonal stretch forging on the titanium alloy octagonal billet once to obtain a titanium alloy forging.

[0065] In some embodiments, the sixth temperature is 900° C. to 1000° C., and the fourth time is 4 h to 5 h.

[0066] In some implementations, performing one-pass octagonal drawing forging on the titanium alloy octagonal billet includes: forging four parallel edges of the titanium alloy octagonal billet with a thirteenth pass reduction, a fourteenth pass reduction, a fifteenth pass reduction, and a sixteenth pass reduction, respectively.

[0067] In some embodiments, the thirteenth pass has a reduction of 140 mm to 200 mm, the fourteenth pass has a reduction of 140 mm to 200 mm, the fifteenth pass has a reduction of 140 mm to 200 mm, and the sixteenth pass has a reduction of 140 mm to 200 mm.

[0068] In some embodiments, the deformation amount of the titanium alloy octagonal billet during the first fire octagonal drawing forging is 20% to 30%.

[0069] In some embodiments, the titanium alloy forging material is in the shape of an octagonal prism having an octagonal cross-section.

[0070] In some embodiments, performing round rod drawing forging on the first titanium alloy ingot includes: using a curved anvil and a forging process matching the curved anvil to draw the titanium alloy forging material through multiple passes and multiple firings.

[0071] In some embodiments, Figure 2 and Figure 3 As shown, the arc anvil includes a first straight portion 1, a first arc portion 2, a second straight portion 3, a bottom 4, a third straight portion 5, a second arc portion 6, and a fourth straight portion 7 connected in sequence. The cross section of the bottom 4 is an arc. The second straight portion 3 and the third straight portion 5 are symmetrically connected to the bottom 4 above both sides of the bottom 4. The radius R of the arc of the bottom 4 is 50mm to 100mm larger than the diameter of the finished titanium alloy round rod. The angle φ between the second straight portion 3 and the section passing through the connection between the second straight portion 3 and the bottom 4 is 15° to 25°. The angle φ between the third straight portion 5 and the section passing through the connection between the third straight portion 5 and the bottom 4 is 15° to 25°. The length a of the arc anvil is 600mm to 1000mm, and the width b is 600mm to 1000mm. The arc anvil can deform the core of the round rod well, which is conducive to improving the uniformity of the core and surface structure and performance of the round rod.

[0072] In some embodiments, the forging process matched with the arc anvil is used to perform multi-pass drawing of the titanium alloy forging material, including: first, two identical arc anvils are arranged symmetrically up and down; second, after heating the titanium alloy forging material to the seventh temperature and keeping it warm for the fifth time, the titanium alloy forging material is drawn for 1 to 2 times in multiple passes, drawn to the finished size of the titanium alloy, and the final forging temperature of each multi-pass drawing is the eighth temperature. During each multi-pass drawing process, the titanium alloy forging material is drawn with the seventeenth pass reduction in each drawing pass, and the feed amount of the titanium alloy forging material is 450 mm to 600 mm. After each drawing pass, the titanium alloy forging material is rotated 90° around the axis before the next drawing pass.

[0073] In some embodiments, the seventh temperature is 900° C. to 950° C., the fifth time is 3 h to 4 h, and the eighth temperature is greater than or equal to 750° C.

[0074] In some embodiments, the reduction in the seventeenth pass is 20% to 30%. In the drawing operation, the reduction in each pass refers to the ratio of the amount of the blank compressed in the height direction to the original height.

[0075] The present invention provides a high-strength titanium alloy, which is manufactured by the forging method of the high-strength titanium alloy of the present invention. The chemical composition of the high-strength titanium alloy is calculated by element mass percentage: Al: 5% to 6.5%, Mo: 1.5% to 3%, V: 1.5% to 2%, Zr: 3% to 4%, Sn: 2.5% to 3.6%, Nb: 0.5% to 1.5%, Si: 0.2% to 0.5%; the balance is Ti and other inevitable impurity elements.

[0076] The high-strength titanium alloy of the present invention is a high-strength titanium alloy developed by optimizing and adjusting the composition of the TA15 alloy, and by adopting a forging method matching the high-strength titanium alloy, that is, a "multi-directional forging" with multiple fires and multiple passes followed by a forging method using upper and lower anvils (arc anvils) of a specific shape for stretching, to obtain a high-strength titanium alloy large-size round bar with a diameter of 300mm to 400mm.

[0077] After annealing, the high-strength titanium alloy of the present invention has a tensile strength of ≥1050MPa, a yield strength of ≥980MPa and an elongation of ≥12% at room temperature.

[0078] The following examples illustrate the application of the high-strength titanium alloy forging method of the present invention in large-size titanium alloy round bars.

[0079] Example 1 Based on the TA15 alloy composition, a high-strength titanium alloy was developed through optimization and adjustment. By adopting a forging method that matches the high-strength titanium alloy, namely "multi-directional forging" with multiple fires and multiple passes followed by a forging method using an arc anvil for stretching, a large-sized round bar of high-strength titanium alloy with a diameter of 305mm was obtained.

[0080] The details are as follows: 1. The chemical composition of the optimized high-strength titanium alloy is calculated by element mass percentage as follows: Al: 5.58%, Mo: 1.61%, V: 1.57%, Zr: 3.22%, Sn: 2.54%, Nb: 0.71%, Si: 0.32%; the remainder is Ti and other inevitable impurity elements.

[0081] 2. The raw materials of titanium sponge, baked TiO2 powder, vanadium aluminum alloy, aluminum molybdenum, zirconium sponge and master alloy containing tin and niobium weighed and prepared according to the above chemical composition ratio are mixed in a mixer, and then electrode blocks are pressed and vacuum plasma welded to form titanium alloy raw materials for electrodes. The titanium alloy raw materials are subjected to vacuum self-consumable smelting three times to obtain a 6-ton titanium alloy ingot with a diameter of Φ 860mm and a length of 1900mm. The titanium alloy ingot is pretreated, and after the riser end of the titanium alloy ingot is cut off, the surface defects and oxide scale of the remaining ingot of the titanium alloy ingot are removed to ensure the quality, and then the remaining ingot of the titanium alloy ingot is cut along the height direction of the remaining ingot of the titanium alloy ingot to obtain 5 sections of the first titanium alloy ingot with a height of 380mm.

[0082] 3. Open forging: Place the first titanium alloy ingot in a resistance furnace, heat it to 1050°C and keep it warm for 5 hours, and perform multi-directional forging of the first titanium alloy ingot in two fires and multiple passes. The multi-directional forging of the first fire and multiple passes includes firstly pressing the first titanium alloy ingot with a full anvil along the first diameter direction of the first titanium alloy ingot at a pass reduction of 80mm, and then rotating the first titanium alloy ingot around the axis 90° and pressing the first titanium alloy ingot with a full anvil along the second diameter direction of the first titanium alloy ingot perpendicular to the first diameter direction at a pass reduction of 80mm, repeating the full anvil pressing in the first diameter direction and the second diameter direction in turn, and then pressing the first titanium alloy ingot with a pass reduction of 40mm along the height direction of the first titanium alloy ingot. The titanium alloy ingot is forged to obtain a first titanium alloy intermediate billet, and then the first titanium alloy intermediate billet is successively forged along a first horizontal direction of the first titanium alloy intermediate billet with a reduction of 80 mm per pass, the first titanium alloy intermediate billet is rotated 90° around an axis and then the first titanium alloy intermediate billet is forged along a second horizontal direction perpendicular to the first horizontal direction of the first titanium alloy intermediate billet with a reduction of 80 mm per pass, and along a height direction of the first titanium alloy intermediate billet with a reduction of 40 mm per pass, while maintaining a final forging temperature greater than or equal to 850°C to obtain a second titanium alloy intermediate billet. The second titanium alloy intermediate billet is placed in a resistance furnace and heated to 1000°C and kept warm for 5 hours before undergoing a second fire and multiple passes of multi-directional forging. This is performed twice, respectively, along the first horizontal direction of the second titanium alloy intermediate billet with a pass reduction of 80 mm, after the second titanium alloy intermediate billet is rotated 90° around the axis, the second titanium alloy intermediate billet is forged along the second horizontal direction perpendicular to the first horizontal direction of the second titanium alloy intermediate billet with a pass reduction of 80 mm, and along the height direction of the second titanium alloy intermediate billet with a pass reduction of 40 mm. After two fires and multiple passes of multi-directional forging, a titanium alloy intermediate billet with a cube shape with a side length of 602 mm is obtained.

[0083] 4. Forging of intermediate billet: The titanium alloy intermediate billet is heated to 1000℃ and kept warm for 4h, and the titanium alloy intermediate billet is subjected to 5 times of multi-directional forging to obtain a titanium alloy octagonal billet. During the forging process, each time of multi-directional forging includes 2 passes of multi-directional forging, and each pass of multi-directional forging is to press down the titanium alloy intermediate billet in the first horizontal direction by 210mm, rotate the titanium alloy intermediate billet around the axis by 90°, and then press down the titanium alloy intermediate billet in the second horizontal direction perpendicular to the first horizontal direction by 210mm, and press down the titanium alloy intermediate billet in the height direction by 210mm. After each time of multi-directional forging, the titanium alloy intermediate billet maintains a cube shape with a side length of 602mm. In each time of multi-directional forging, the deformation of the titanium alloy intermediate billet in the first horizontal direction, the second horizontal direction and the height direction is 35%, and the final forging temperature of each time of multi-directional forging is not less than 750℃.

[0084] 5. Eight-sided drawing forging: Heat the titanium alloy eight-sided billet to 950℃ and keep it warm for 4h, and perform one-time eight-sided drawing forging on the titanium alloy eight-sided billet. Forge the four parallel edges of the titanium alloy eight-sided billet with a pass reduction of 150mm, a pass reduction of 150mm, a pass reduction of 150mm, and a pass reduction of 150mm to obtain the titanium alloy forging. The deformation of the titanium alloy eight-sided billet in one-time eight-sided drawing forging is 25%.

[0085] 6. Round bar drawing forging: The designed arc anvil and the forging process matched with the arc anvil are used to draw the titanium alloy forging material for round bar drawing forging. The radius R of the arc of the bottom 4 of the arc anvil is 400mm, the angle φ between the second straight part 3 and the section passing through the connection between the second straight part 3 and the bottom 4 is 15°, the angle φ between the third straight part 5 and the section passing through the connection between the third straight part 5 and the bottom 4 is 15°, the length a of the arc anvil is 600mm, and the width b is 700mm. The forging process matched with the arc anvil is used to perform multi-pass drawing of the titanium alloy forging material in one fire, including: two identical arc anvils are arranged symmetrically up and down, the titanium alloy forging material is heated to 900℃ and kept warm for 3 hours, and then the titanium alloy forging material is drawn in one fire and in multiple passes, the titanium alloy forging material is drawn with a 20% pass reduction in each drawing pass, the feed amount of the titanium alloy forging material is 450mm, and after each drawing pass, the titanium alloy forging material is rotated 90° around the axis and then drawn in the next pass. After being drawn to the finished size of the titanium alloy, it is air-cooled to room temperature to obtain a high-strength titanium alloy.

[0086] The size of the obtained high-strength titanium alloy is Φ305mm×2970mm. After annealing, the tensile strength is 1142MPa, the yield strength is 1075MPa, and the elongation is 12.5% ​​at room temperature. The microstructure of the core of the high-strength titanium alloy round bar is as follows: Figure 4 shown.

[0087] Example 2 Based on the TA15 alloy composition, a high-strength titanium alloy was developed through optimization and adjustment. By adopting a forging method that matches the high-strength titanium alloy, namely "multi-directional forging" with multiple fires and multiple passes followed by a forging method using an arc anvil for stretching, a large-sized round bar of high-strength titanium alloy with a diameter of 400mm was obtained.

[0088] The details are as follows: 1. The chemical composition of the optimized high-strength titanium alloy is calculated by element mass percentage as follows: Al: 6.44%, Mo: 2.91%, V: 1.94%, Zr: 3.72%, Sn: 3.46%, Nb: 1.48%, Si: 0.46%; the remainder is Ti and other inevitable impurity elements.

[0089] 2. The raw materials of titanium sponge, baked TiO2 powder, vanadium aluminum alloy, aluminum molybdenum, zirconium sponge and master alloy containing tin and niobium weighed and prepared according to the above chemical composition ratio are mixed in a mixer, and then electrode blocks are pressed and vacuum plasma welded to form titanium alloy raw materials for electrodes. The titanium alloy raw materials are subjected to vacuum self-consumable smelting three times to obtain a 6-ton titanium alloy ingot with a diameter of Φ 860mm and a length of 2000mm. The titanium alloy ingot is pretreated, and after the riser end of the titanium alloy ingot is cut off, the surface defects and oxide scale of the remaining ingot of the titanium alloy ingot are removed to ensure the quality, and then the remaining ingot of the titanium alloy ingot is cut along the height direction of the remaining ingot of the titanium alloy ingot to obtain 5 sections of the first titanium alloy ingot with a height of 400mm.

[0090] 3. Open forging: Place the first titanium alloy ingot in a resistance furnace, heat it to 1150℃ and keep it warm for 5.5h, and perform multi-directional forging of the first titanium alloy ingot in two fires and multiple passes. The multi-directional forging of the first fire and multiple passes includes firstly pressing the first titanium alloy ingot with full anvil down at 80mm per pass along the first diameter direction of the first titanium alloy ingot, and then rotating the first titanium alloy ingot around the axis 90° and pressing the first titanium alloy ingot with full anvil down at 80mm per pass along the second diameter direction of the first titanium alloy ingot perpendicular to the first diameter direction, repeating the full anvil down pressing in the first diameter direction and the second diameter direction respectively, and then pressing the first titanium alloy ingot with full anvil down at 40mm per pass along the height direction of the first titanium alloy ingot. The titanium alloy ingot is forged to obtain a first titanium alloy intermediate billet, and then the first titanium alloy intermediate billet is successively forged along a first horizontal direction of the first titanium alloy intermediate billet with a reduction of 80 mm per pass, the first titanium alloy intermediate billet is rotated 90° around an axis and then the first titanium alloy intermediate billet is forged along a second horizontal direction perpendicular to the first horizontal direction of the first titanium alloy intermediate billet with a reduction of 80 mm per pass, and along a height direction of the first titanium alloy intermediate billet with a reduction of 40 mm per pass, while maintaining a final forging temperature greater than or equal to 850°C to obtain a second titanium alloy intermediate billet. The second titanium alloy intermediate billet is placed in a resistance furnace and heated to 1100°C and kept warm for 5 hours before undergoing a second fire and multiple passes of multi-directional forging. This is performed twice, respectively, along the first horizontal direction of the second titanium alloy intermediate billet with a reduction of 80 mm per pass, the second titanium alloy intermediate billet is rotated 90° around the axis and then forged along the second horizontal direction of the second titanium alloy intermediate billet perpendicular to the first horizontal direction with a reduction of 80 mm per pass, and along the height direction of the second titanium alloy intermediate billet with a reduction of 40 mm per pass. After two fires and multiple passes of multi-directional forging, a cube-shaped titanium alloy intermediate billet with a side length of 608 mm is obtained.

[0091] 4. Forging of intermediate billet: The titanium alloy intermediate billet is heated to 1100℃ and kept warm for 5h, and the titanium alloy intermediate billet is subjected to 6-fire multi-directional forging to obtain a titanium alloy octagonal billet. During the forging process, each fire multi-directional forging includes 2 passes of multi-directional forging, and each pass of multi-directional forging is to press down the titanium alloy intermediate billet in the first horizontal direction by 275mm, rotate the titanium alloy intermediate billet around the axis by 90°, and then press down the titanium alloy intermediate billet in the second horizontal direction perpendicular to the first horizontal direction by 275mm, and press down the titanium alloy intermediate billet in the height direction by 275mm. After each fire multi-directional forging, the titanium alloy intermediate billet maintains a cube shape with a side length of 608mm. In each fire multi-directional forging, the deformation of the titanium alloy intermediate billet in the first horizontal direction, the second horizontal direction and the height direction are all 45%, and the final forging temperature of each fire multi-directional forging is not less than 750℃.

[0092] 5. Eight-sided drawing forging: Heat the titanium alloy eight-sided billet to 1000℃ and keep it warm for 4h, and perform one-time eight-sided drawing forging on the titanium alloy eight-sided billet. Forge the four parallel edges of the titanium alloy eight-sided billet with a pass reduction of 180mm, 180mm, 180mm, and 180mm, respectively, to obtain the titanium alloy forging. The deformation of the titanium alloy eight-sided billet in one-time eight-sided drawing forging is 30%.

[0093] 6. Round bar drawing forging: The designed arc anvil and the forging process matched with the arc anvil are used to draw the titanium alloy forging material for round bar drawing forging. The radius R of the arc at the bottom 4 of the arc anvil is 500mm, the angle φ between the second straight portion 3 and the section passing through the connection between the second straight portion 3 and the bottom 4 is 25°, the angle φ between the third straight portion 5 and the section passing through the connection between the third straight portion 5 and the bottom 4 is 25°, the length a of the arc anvil is 1000mm, and the width b is 1000mm. The forging process matched with the arc anvil is used to perform multi-pass drawing of the titanium alloy forging material in one fire, including: two identical arc anvils are arranged symmetrically up and down, the titanium alloy forging material is heated to 950℃ and kept warm for 3h, and then the titanium alloy forging material is drawn in one fire and in multiple passes, and the titanium alloy forging material is drawn with a 30% pass reduction in each drawing pass, and the feed amount of the titanium alloy forging material is 600mm. After each drawing pass, the titanium alloy forging material is rotated 90° around the axis and then drawn in the next pass. After being drawn to the finished size of the titanium alloy, it is air-cooled to room temperature to obtain a high-strength titanium alloy.

[0094] The size of the obtained high-strength titanium alloy is Φ400mm×1790mm. After annealing, the tensile strength is 1160MPa, the yield strength is 1090MPa, and the elongation is 12.1% at room temperature. The microstructure of the core of the high-strength titanium alloy round bar is as follows: Figure 5 shown.

[0095] The forging method of the high-strength titanium alloy of the present invention is a forging method matched with a high-strength titanium alloy developed through optimization and adjustment on the basis of the composition of the TA15 alloy. It is a forging method in which the titanium alloy is subjected to multiple "multi-directional forgings" and then stretched using upper and lower anvils of a specific shape to obtain a large-sized round rod of a high-strength titanium alloy with a diameter of 300mm to 400mm. The forging method of the high-strength titanium alloy of the present invention can deform the core of the round rod well, which is beneficial to the uniformity of the core and surface structure and performance of the round rod. The application of the forging method of the high-strength titanium alloy of the present invention can realize the development of a new type of high-strength titanium alloy, which mainly involves composition design and forging process design, has certain economic benefits, and is of great significance to improving the performance of titanium alloy products.

[0096] So far, various embodiments of the present invention have been described in detail. In order to avoid obscuring the concept of the present invention, some details known in the art are not described. Based on the above description, those skilled in the art can fully understand how to implement the technical solution disclosed here.

[0097] Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It should be understood by those skilled in the art that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict.

Claims

1. A forging method for a high-strength titanium alloy, characterized in that: include: Performing vacuum consumable smelting on a titanium alloy raw material to obtain a titanium alloy ingot, performing pretreatment on the titanium alloy ingot to obtain a first titanium alloy ingot, and sequentially performing blank forging, intermediate blank forging, eight-way drawing forging, and round bar drawing forging on the first titanium alloy ingot, followed by air cooling to room temperature to obtain a high-strength titanium alloy; The first titanium alloy ingot is subjected to blank forging, comprising: heating the first titanium alloy ingot to a first temperature and keeping the temperature for a first time, and then performing two-pass multi-directional forging on the first titanium alloy ingot to obtain a titanium alloy intermediate blank; The round bar drawing forging of the first titanium alloy ingot includes: using a curved anvil and a forging process matching the curved anvil to draw the titanium alloy forging material after the eight-way drawing forging in multiple fires and multiple passes.

2. The forging method of high-strength titanium alloy according to claim 1, characterized in that: Pre-treating the titanium alloy ingot to obtain the first titanium alloy ingot includes: cutting off the riser end of the titanium alloy ingot, removing surface defects and oxide scale of the remaining ingot of the titanium alloy ingot, and cutting the remaining ingot of the titanium alloy ingot along the height direction of the remaining ingot of the titanium alloy ingot to obtain the first titanium alloy ingot.

3. The forging method of high-strength titanium alloy according to claim 1, characterized in that: The method of performing multi-directional forging of the first titanium alloy ingot with two passes and multiple times includes: performing multi-directional forging of the first titanium alloy ingot with a first pass and multiple times to obtain a second titanium alloy intermediate billet; heating the second titanium alloy intermediate billet to a second temperature; and then performing multi-directional forging of the second titanium alloy intermediate billet with a second pass and multiple times to obtain a second titanium alloy intermediate billet.

4. The forging method of high-strength titanium alloy according to claim 3, characterized in that: The first titanium alloy ingot is subjected to a first-fire multi-pass multi-directional forging to obtain a second titanium alloy intermediate billet, comprising the following steps: Step 1, fully anvil pressing the first titanium alloy ingot along a first horizontal direction of the first titanium alloy ingot according to a first pass pressing amount, and then fully anvil pressing the first titanium alloy ingot along a second horizontal direction of the first titanium alloy ingot at 90° to the first horizontal direction of the first titanium alloy ingot according to a second pass pressing amount; Step 2, repeat step 1; Step 3, forging the first titanium alloy ingot along the vertical direction according to the third pass reduction to obtain a first titanium alloy intermediate billet; Step 4, obtain the second titanium alloy intermediate billet in the following manner: forge the first titanium alloy intermediate billet in sequence by pressing down the first horizontal direction of the first titanium alloy intermediate billet for a fourth time, pressing down the second horizontal direction of the first titanium alloy intermediate billet at an angle of 90° to the first horizontal direction of the first titanium alloy intermediate billet for a fifth time, and pressing down the vertical direction for a sixth time.

5. The forging method of high-strength titanium alloy according to claim 4, characterized in that: The second titanium alloy intermediate billet is subjected to multi-directional forging with multiple passes of the second fire, including: performing 1 to 2 passes of multi-directional forging, wherein each pass of the multi-directional forging is forging the second titanium alloy intermediate billet in sequence along the first horizontal direction of the second titanium alloy intermediate billet according to the seventh pass reduction, along the second horizontal direction of the second titanium alloy intermediate billet at 90° to the first horizontal direction of the second titanium alloy intermediate billet according to the eighth pass reduction, and along the vertical direction according to the ninth pass reduction.

6. The forging method of high-strength titanium alloy according to claim 1, characterized in that: The intermediate billet forging of the first titanium alloy ingot comprises: heating the titanium alloy intermediate billet to a fourth temperature and keeping the temperature for a third time, and then performing multi-fire multi-directional forging on the titanium alloy intermediate billet to obtain a titanium alloy octagonal billet.

7. The forging method of high-strength titanium alloy according to claim 6, characterized in that: The titanium alloy intermediate billet is subjected to multi-directional forging for multiple times, including: performing multi-directional forging for the titanium alloy intermediate billet for 5 to 6 times, wherein each multi-directional forging includes 1 to 2 multi-directional forging passes, and each multi-directional forging pass is forging the titanium alloy intermediate billet in sequence along a first horizontal direction of the titanium alloy intermediate billet according to a tenth pass reduction, along a second horizontal direction of the titanium alloy intermediate billet which is 90° to the first horizontal direction of the titanium alloy intermediate billet according to an eleventh pass reduction, and along a vertical direction according to a twelfth pass reduction.

8. The forging method of high-strength titanium alloy according to claim 6, characterized in that: The octagonal drawing forging of the first titanium alloy ingot includes: heating the titanium alloy octagonal billet to a sixth temperature and keeping the temperature for a fourth time, and then performing octagonal drawing forging on the titanium alloy octagonal billet once to obtain the titanium alloy forging material.

9. The forging method of high-strength titanium alloy according to claim 1, characterized in that: The forging process matched with the arc anvil is used to perform multi-fire and multi-pass drawing on the titanium alloy forging after eight-way drawing forging, including: first, two identical arc anvils are arranged symmetrically up and down; second, the titanium alloy forging is heated to the seventh temperature and kept warm for the fifth time, and then the titanium alloy forging is drawn for 1 to 2 times in multiple passes. During each fire and multi-pass drawing process, the titanium alloy forging is drawn with the seventeenth pass reduction in each drawing pass. The feed amount of the titanium alloy forging is 450mm to 600mm. After each drawing pass, the titanium alloy forging is rotated 90° around the axis before the next drawing pass.

10. A high-strength titanium alloy manufactured by the forging method of the high-strength titanium alloy according to any one of claims 1 to 9, characterized in that: The chemical composition of the high-strength titanium alloy is calculated by element mass percentage as follows: Al: 5% to 6.5%, Mo: 1.5% to 3%, V: 1.5% to 2%, Zr: 3% to 4%, Sn: 2.5% to 3.6%, Nb: 0.5% to 1.5%, Si: 0.2% to 0.5%; the remainder is Ti and other inevitable impurity elements.

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