Method for improving component uniformity of large-specification TB6 titanium alloy cast ingot

Abstract

The invention discloses a method for improving the component uniformity of a large-specification TB6 titanium alloy cast ingot, which comprises the following steps of: smelting a consumable electrode by adopting vacuum consumable arc for three times, smelting by adopting a mode of reducing current step by step in the smelting process, starting high-stable arc current, and finally preparing the TB6 titanium alloy cast ingot. Welding is carried out before secondary smelting, and segregation or inclusion caused by the fact that welding slag falls into a molten pool due to welding before tertiary smelting is avoided; in the smelting process, current is reduced step by step, low current is adopted in the last time of smelting so as to reduce the depth of a molten pool, and high-stable arc current is adopted, so that elements are uniformly distributed, beta spots are effectively prevented from being generated, and finally cast ingots with uniform components are obtained. By means of the method, multiple batches of TB6 alloy ingots with the diameter being 520-750 mm have been successfully prepared, and the deviation between the actual content of metal elements and the target value is within 0.1%.

Description

Technical Field

[0001] This invention belongs to the field of high-quality titanium alloy materials technology, and relates to the manufacture of TB6 titanium alloy, specifically to a method for improving the compositional uniformity of large-size TB6 titanium alloy ingots. Background Technology

[0002] Compositional uniformity is the most critical indicator for evaluating TB6 titanium alloy ingots. Workpiece failures and other accidents caused by compositional segregation are common, making improving ingot compositional uniformity a primary problem to be solved in the field of titanium alloy preparation. The nominal composition of TB6 titanium alloy is Ti-10V-2Fe-3Al, a typical high-strength β-titanium alloy with good plasticity. The large amount of slow eutectoid β elements (such as Fe) makes the ingot prone to β spots, which are generally concentrated in the upper part of the ingot and characterized by low strength and low plasticity. β-spot regions lead to uneven elemental distribution in the ingot, thus affecting the overall material properties.

[0003] Compared to small and medium-sized TB6 titanium alloy ingots, large-sized TB6 titanium alloy ingots are more prone to β-spot regions. The main reasons are: First, the cooling rate in the central region of large-sized ingots is much lower than that on the surface, resulting in a longer solidification time and allowing β-elements to accumulate sufficiently between dendrites or at grain boundaries. Second, the greater depth of the molten pool in large-sized ingots exacerbates the density segregation of β-elements, forming macroscopic segregation bands. Eliminating segregation in large-sized ingots requires high-temperature, long-duration diffusion, but this easily leads to oxidation problems. Therefore, a more stringent melting environment and more precise melting parameters are needed to ensure uniform element distribution in the ingot, significantly increasing the difficulty of process optimization. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method to improve the compositional uniformity of large-size TB6 titanium alloy ingots, and to solve the technical problem that large-size TB6 ingots are prone to forming β-spot regions during smelting, resulting in uneven element distribution.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for improving the compositional uniformity of large-size TB6 titanium alloy ingots, the method specifically includes the following steps: Step 1: Mix the raw materials; Step 2: Press the raw materials mixed in Step 1 into electrode blocks, and then weld them together to obtain consumable electrodes. Step 3: Perform three vacuum consumable arc melting processes on the consumable electrode obtained in Step 2: Step 3.1, First Melting: After checking for any abnormalities, seal the furnace and begin vacuuming until the vacuum level inside the furnace reaches 1.0 × 10⁻⁶. -2 ~1.5×10-2 After torsion, smelting begins. The smelting process involves gradually reducing the current, with the smelting current ranging from 3 to 18 kA. Once the molten pool is intact, the arc-stabilizing current is activated, with a value of 44 to 46 A. When 1 / 3 of the weight has been melted, the smelting current is reduced from 18 kA to 13 to 14 kA. When the remaining 1 / 3 of the ingot weight has been melted, the current is reduced by 2 kA for every 200 kg melted, resulting in a primary ingot. The two primary ingots are then welded together. Step 3.2, Secondary Melting: Vacuuming is performed until the vacuum level inside the furnace reaches 4.0 × 10⁻⁶. -3 ~4.3×10 -3 After torsion, smelting begins. The smelting process involves gradually reducing the current, with the smelting current ranging from 8 to 18 kA. Once the molten pool is intact, the arc-stabilizing current is activated, with a value of 44 to 46 A. When 1 / 3 of the weight has been smelted, the smelting current is reduced from 18 kA to 15 to 16 kA. When the remaining 1 / 3 of the weight is smelted for casting, the current is reduced by 4 kA for every 800 kg melted, resulting in a secondary ingot.

[0006] Step 3.3, Third Melting: Vacuuming is performed until the vacuum level inside the furnace reaches 4.2 × 10⁻⁶. -3 ~4.5×10 -3 After torsion, smelting begins; the smelting process adopts a step-by-step current reduction method, with the smelting current between 6 and 16 kA; after the molten pool is well-established, the arc stabilizing current is turned on, with the arc stabilizing current value being 25 to 35 A; when 1 / 3 of the weight has been smelted, the smelting current is reduced from 16 kA to 12 kA, and when 100 kg remains, the current is reduced to 6 kA, resulting in a three-stage ingot.

[0007] Step four: Place the liquid melt obtained after melting in step three into a crucible for cooling. After solidification, demold and remove from the furnace to obtain a large-size TB6 titanium alloy ingot.

[0008] The present invention also has the following technical features: Specifically, in step one, the raw materials include sponge titanium, aluminum-vanadium-iron alloy, aluminum-vanadium alloy, aluminum granules, and titanium dioxide; the mixing time is 2 to 5 minutes.

[0009] Specifically, step two includes: first, evenly arranging a small amount of sponge titanium pads in the electrode block mold, placing aluminum foil on top, adding the mixed raw materials into the mold in batches, and then pressing them into several electrode blocks; placing the obtained electrode blocks in a vacuum plasma welding box for welding to obtain consumable electrodes.

[0010] Specifically, in step two, the mixed raw materials are added to the mold in four batches. The pressure for the first two pressings is 2500t, and the pressure for the last two pressings is 8000t.

[0011] Specifically, in step two, the current during electrode block welding is 500-600A.

[0012] Specifically, in step 3.1, the current during the first ingot welding is 500-600A.

[0013] Specifically, in step four, the cooling time is 7 to 10 hours.

[0014] The method described above is applicable to the preparation of TB6 titanium alloy ingots with diameters of Φ520–750 mm.

[0015] The beneficial technical effects of this invention compared to the prior art are as follows: (I) This invention performs welding before the second melting process to avoid the possibility of weld slag falling into the molten pool and causing segregation or inclusions due to welding before the third melting process. During the melting process, the current is gradually reduced, and a small current is used in the final melting process to reduce the depth of the molten pool. A high-stability arc current is also used to ensure uniform distribution of elements, effectively preventing the formation of β spots, and ultimately obtaining an ingot with uniform composition. Using the method of this invention, multiple batches of TB6 alloy ingots with a diameter of Φ520mm to Φ750mm have been successfully prepared, and the actual content of metal elements deviates from the target value by less than 0.1%.

[0016] (II) The present invention strictly controls the vacuum degree in the furnace during the smelting process to prevent impurity elements such as O from mixing in, thereby further ensuring the uniformity of the ingot composition.

[0017] (III) The process of the present invention is simple, easy to operate, and controllable. The riser removal area of ​​the ingot is small, which can effectively reduce costs and provide technical support for the future production of larger TB6 alloy ingots. Attached Figure Description

[0018] Figure 1 Comparative diagrams of the molten pool morphology at different times in Comparative Example 1 (constant current) and Example 1 (gradually decreasing current).

[0019] Figure 2 This is a comparison diagram of the elemental distribution of ingots in Comparative Example 1 (constant current) and Example 1 (gradually decreasing current).

[0020] The technical solution of the present invention will be further described below with reference to the embodiments. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, all raw materials used in this invention are those known in the art.

[0022] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0023] Example 1: This embodiment provides a method for improving the compositional uniformity of large-size TB6 titanium alloy ingots, which specifically includes the following steps: Step 1: Mixing raw materials: Weigh sponge titanium, aluminum-vanadium-iron alloy, aluminum-vanadium alloy, aluminum granules, and titanium dioxide according to the specified proportions, and place them in a mixer for uniform mixing and stirring for 3 minutes. In this embodiment, the ingot composition is: V 10.2 wt%, Fe 1.8 wt%, Al 3.2 wt%, O 0.1 wt%, with the balance being Ti.

[0024] Step two involves pressing the mixed raw materials from step one into electrode blocks, followed by welding to obtain consumable electrodes. First, a small amount of titanium sponge is evenly distributed as a base in the electrode block mold, with aluminum foil placed on top. The mixed raw materials are added to the mold in four batches. After the first two additions, a light pressure of 2500t is applied, and after the last two additions, a pressure of 8000t is applied to press the materials into several electrode blocks. These electrode blocks are then placed in a vacuum plasma welding box and welded at a current of 550A to obtain the consumable electrodes.

[0025] Step three involves three vacuum arc melting processes on the consumable electrode obtained in step two. The melting route is "melting two primary ingots → welding → secondary melting → tertiary melting," with the ingot orientation reversed during the second and third melting processes. Details are as follows: Step 3.1, First Melting: After checking for any abnormalities, seal the furnace and begin vacuuming until the vacuum level inside the furnace reaches 1.2 × 10⁻⁶. -2 After torsion, smelting begins. The smelting process involves gradually reducing the current, with the smelting current ranging from 3 to 18 kA. Once the molten pool is intact, the arc-stabilizing current is activated at 45 A. When 1 / 3 of the weight has been melted, the smelting current is reduced from 18 kA to 13 kA. When the remaining 1 / 3 of the weight of the ingot has been melted, the current is reduced by 2 kA for every 200 kg melted, resulting in a primary ingot. The two primary ingots are then welded together with a welding current of 550 A.

[0026] Step 3.2, Secondary Melting: Vacuuming is performed until the vacuum level inside the furnace reaches 4.0 × 10⁻⁶. -3After torsion, smelting begins. The smelting process involves gradually reducing the current, with the smelting current ranging from 8 to 18 kA. Once the molten pool is intact, the arc-stabilizing current is activated at 45 A. When 1 / 3 of the weight has been smelted, the smelting current is reduced from 18 kA to 16 kA. When the remaining 1 / 3 of the weight is melted for casting, the current is reduced by 4 kA for every 800 kg melted, resulting in a secondary ingot.

[0027] Step 3.3, Third Melting: Vacuuming is performed until the vacuum level inside the furnace reaches 4.2 × 10⁻⁶. -3 After torsion, smelting begins; the smelting process adopts a step-by-step current reduction method, with the smelting current between 6 and 16 kA; after the molten pool is intact, the arc stabilizing current is turned on, with an arc stabilizing current value of 30 A; when 1 / 3 of the weight has been smelted, the smelting current is reduced from 16 kA to 12 kA, and when 100 kg remains, the current is reduced to 6 kA, resulting in a three-stage ingot.

[0028] Step four: Place the liquid melt obtained after melting in step three into a crucible for cooling for 7 hours. After solidification, demold and remove from the furnace to obtain a large-size TB6 titanium alloy ingot.

[0029] In this embodiment, a 750mm TB6 titanium alloy ingot was finally obtained. Its elemental content distribution and molten pool morphology are shown in Table 1 below. Figure 1 and Figure 2 As shown.

[0030] Table 1. Component content distribution in different parts of the TB6 titanium alloy ingot in Example 1

[0031] Example 2: This embodiment provides a method for improving the compositional uniformity of large-size TB6 titanium alloy ingots, which specifically includes the following steps: Step 1: Mixing raw materials: Weigh sponge titanium, aluminum-vanadium-iron alloy, aluminum-vanadium alloy, aluminum granules, and titanium dioxide according to the specified proportions, and place them in a mixer for uniform mixing and stirring for 3 minutes. In this embodiment, the ingot composition is: V 10 wt%, Fe 1.8 wt%, Al 3.2 wt%, O 0.1 wt%, with the balance being Ti.

[0032] Step two involves pressing the mixed raw materials from step one into electrode blocks, followed by welding to obtain consumable electrodes. First, a small amount of titanium sponge is evenly distributed as a base in the electrode block mold, with aluminum foil placed on top. The mixed raw materials are added to the mold in four batches. After the first two additions, a light pressure of 2500t is applied, and after the last two additions, a pressure of 8000t is applied to press the materials into several electrode blocks. These electrode blocks are then placed in a vacuum plasma welding box and welded at a current of 550A to obtain the consumable electrodes.

[0033] Step three involves three vacuum arc melting processes on the consumable electrode obtained in step two. The melting route is (melting of two primary ingots → welding → secondary melting → tertiary melting). During the second and third melting processes, the ingot orientation is reversed to the opposite direction of the previous melting processes. Details are as follows: Step 3.1, First Melting: After checking for any abnormalities, seal the furnace and begin vacuuming until the vacuum level inside the furnace reaches 1.5 × 10⁻⁶. -2 After torsion, smelting begins. The smelting process involves gradually reducing the current, with the smelting current ranging from 3 to 18 kA. Once the molten pool is intact, the arc-stabilizing current is activated at 45 A. When 1 / 3 of the weight has been melted, the smelting current is reduced from 18 kA to 14 kA. When the remaining 1 / 3 of the weight of the ingot has been melted, the current is reduced by 2 kA for every 200 kg melted, resulting in a primary ingot. The two primary ingots are then welded together with a welding current of 550 A.

[0034] Step 3.2, Secondary Melting: Vacuuming is performed until the vacuum level inside the furnace reaches 4.3 × 10⁻⁶. -3 After torsion, smelting begins. The smelting process involves gradually reducing the current, with the smelting current ranging from 8 to 18 kA. Once the molten pool is intact, the arc-stabilizing current is activated at 45 A. When 1 / 3 of the weight has been smelted, the smelting current is reduced from 18 kA to 15 kA. When the remaining 1 / 3 of the weight is melted for casting, the current is reduced by 4 kA for every 800 kg melted, resulting in a secondary ingot.

[0035] Step 3.3, Third Melting: Vacuuming is performed until the vacuum level inside the furnace reaches 4.5 × 10⁻⁶. -3 After torsion, smelting begins; the smelting process adopts a step-by-step current reduction method, with the smelting current between 6 and 16 kA; after the molten pool is intact, the arc stabilizing current is turned on, with an arc stabilizing current value of 30 A; when 1 / 3 of the weight has been smelted, the smelting current is reduced from 16 kA to 12 kA, and when 100 kg remains, the current is reduced to 6 kA, resulting in a three-stage ingot.

[0036] Step four: Place the liquid melt obtained after melting in step three into a crucible for cooling for 7 hours. After solidification, demold and remove from the furnace to obtain a large-size TB6 titanium alloy ingot.

[0037] In this embodiment, a TB6 titanium alloy ingot with a diameter of 750mm was finally obtained. Its elemental composition distribution is shown in Table 2 below.

[0038] pass Figure 1 The schematic diagram of the molten pool in the simulated three-stage melting of the ingot shows that the melting method of gradually reducing the current and starting a stable arc has a significant improvement on the morphology of the molten pool. Figure 2The smelting method of the present invention can significantly improve the uniformity of element distribution.

[0039] Table 2. Component content distribution in different parts of the TB6 titanium alloy ingot in Example 2.

[0040] Example 3: This embodiment provides a method for improving the compositional uniformity of large-size TB6 titanium alloy ingots, which specifically includes the following steps: Step 1: Mixing raw materials: Weigh sponge titanium, aluminum-vanadium-iron alloy, aluminum-vanadium alloy, aluminum granules, and titanium dioxide according to the specified proportions, and place them in a mixer for uniform mixing and stirring for 3 minutes. In this embodiment, the ingot composition is: V 10 wt%, Fe 1.8 wt%, Al 3.2 wt%, O 0.1 wt%, with the balance being Ti.

[0041] Step two involves pressing the mixed raw materials from step one into electrode blocks, followed by welding to obtain consumable electrodes. First, a small amount of titanium sponge is evenly distributed as a base in the electrode block mold, with aluminum foil placed on top. The mixed raw materials are added to the mold in four batches. After the first two additions, a light pressure of 2500t is applied, and after the last two additions, a pressure of 8000t is applied to press the materials into several electrode blocks. These electrode blocks are then placed in a vacuum plasma welding box and welded at a current of 550A to obtain the consumable electrodes.

[0042] Step three involves three vacuum arc melting processes on the consumable electrode obtained in step two. The melting route is (melting of two primary ingots → welding → secondary melting → tertiary melting). During the second and third melting processes, the ingot orientation is reversed to the opposite direction of the previous melting processes. Details are as follows: Step 3.1, First Melting: After checking for any abnormalities, seal the furnace and begin vacuuming until the vacuum level inside the furnace reaches 1.0 × 10⁻⁶. -2 After torsion, smelting begins. The smelting process involves gradually reducing the current, with the smelting current ranging from 3 to 18 kA. Once the molten pool is intact, the arc-stabilizing current is activated at 45 A. When 1 / 3 of the weight has been melted, the smelting current is reduced from 18 kA to 14 kA. When the remaining 1 / 3 of the weight of the ingot has been melted, the current is reduced by 2 kA for every 200 kg melted, resulting in a primary ingot. The two primary ingots are then welded together with a welding current of 550 A.

[0043] Step 3.2, Secondary Melting: Vacuuming is performed until the vacuum level inside the furnace reaches 4.1 × 10⁻⁶. -3After torsion, smelting begins. The smelting process involves gradually reducing the current, with the smelting current ranging from 8 to 18 kA. Once the molten pool is intact, the arc-stabilizing current is activated at 45 A. When 1 / 3 of the weight has been smelted, the smelting current is reduced from 18 kA to 16 kA. When the remaining 1 / 3 of the weight is melted for casting, the current is reduced by 4 kA for every 800 kg melted, resulting in a secondary ingot.

[0044] Step 3.3, Third Melting: Vacuuming is performed until the vacuum level inside the furnace reaches 4.2 × 10⁻⁶. -3 After torsion, smelting begins; the smelting process adopts a step-by-step current reduction method, with the smelting current between 6 and 16 kA; after the molten pool is intact, the arc stabilizing current is turned on, with an arc stabilizing current value of 30 A; when 1 / 3 of the weight has been smelted, the smelting current is reduced from 16 kA to 12 kA, and when 100 kg remains, the current is reduced to 6 kA, resulting in a three-stage ingot.

[0045] Step four: Place the molten liquid obtained after melting in step three into a crucible for cooling for 5 hours. After solidification, demold and remove from the furnace to obtain a large-size TB6 titanium alloy ingot.

[0046] In this embodiment, a 520mm TB6 titanium alloy ingot was finally obtained, and its elemental content distribution is shown in Table 3 below.

[0047] Table 3. Component content distribution in different parts of the TB6 titanium alloy ingot in Example 3.

[0048] Comparative Example 1: This comparative example presents a method for improving the compositional uniformity of large-size TB6 titanium alloy ingots. This method is basically the same as that in Example 1, except that step four does not use a melting method of gradually decreasing current.

[0049] In this comparative example, step four includes: Step 3.1, First Melting: After checking for any abnormalities, seal the furnace and begin vacuuming until the vacuum level inside the furnace reaches 1.2 × 10⁻⁶. -2 After torsion, melting begins with a melting current between 3 and 18 kA. Once the molten pool is intact, the arc stabilizing current is turned on at 45 A. When the remaining weight is 200 kg, the melting current is reduced from 18 kA to 4 kA to obtain a primary ingot. The two primary ingots are then welded with a welding current of 550 A.

[0050] Step 3.2, Secondary Melting: Vacuuming is performed until the vacuum level inside the furnace reaches 4.2 × 10⁻⁶. -3After torsion, smelting begins with a smelting current between 8 and 18 kA. Once the molten pool is intact, the arc stabilizing current is turned on at 45 A. When the remaining weight is 200 kg, the smelting current is reduced from 18 kA to 8 kA to obtain a secondary ingot.

[0051] Step 3.3, Third Melting: Vacuuming is performed until the vacuum level inside the furnace reaches 4.2 × 10⁻⁶. -3 After torsion, smelting begins with a smelting current between 6 and 16 kA. Once the molten pool is intact, the arc stabilizing current is activated at 30 A. When the remaining weight is 200 kg, the smelting current is reduced from 16 kA to 6 kA to obtain a tertiary ingot.

[0052] In this comparative example, a TB6 titanium alloy ingot with a diameter of 750mm was finally obtained. The elemental content distribution and molten pool morphology are shown in Table 4 below. Figure 1 and Figure 2 As shown.

[0053] Table 4. Component content distribution in different parts of the TB6 titanium alloy ingot in Comparative Example 1

[0054] Comparative Example 2: This comparative example presents a method for improving the compositional uniformity of large-size TB6 titanium alloy ingots. This method is essentially the same as that in Example 1, except that the arc-stabilizing current in step three is different. The method specifically includes the following steps: Step 1: Mixing raw materials: Weigh sponge titanium, aluminum-vanadium-iron alloy, aluminum-vanadium alloy, aluminum granules, and titanium dioxide according to the specified proportions, and place them in a mixer to mix evenly for 3 minutes. In this comparative example, the ingot composition is: V 10.0 wt%, Fe 2.0 wt%, Al 3.2 wt%, O 0.1 wt%, with the balance being Ti.

[0055] Step 2: Press the raw materials mixed in Step 1 into electrode blocks, and then weld them to obtain consumable electrodes. In this comparative example, Step 2 is exactly the same as Step 2 in Example 1.

[0056] Step 3 includes: Step 3.1, primary melting: After checking for any abnormalities, seal the furnace and perform vacuuming until the vacuum level inside the furnace reaches 1.0 × 10⁻⁶. -2 After torsion, smelting begins. The smelting process involves gradually reducing the current, with the smelting current ranging from 3 to 18 kA. Once the molten pool is intact, the arc-stabilizing current is activated at 5 A. When 1 / 3 of the weight has been smelted, the smelting current is reduced from 18 kA to 14 kA. When the remaining 1 / 3 of the weight of the ingot has been smelted, the current is reduced by 2 kA for every 200 kg melted, resulting in a primary ingot. The two primary ingots are then welded together with a welding current of 550 A.

[0057] Step 3.2, Secondary Melting: Vacuuming is performed until the vacuum level inside the furnace reaches 4.1 × 10⁻⁶. -3 After torsion, smelting begins. The smelting process involves gradually reducing the current, with the smelting current ranging from 8 to 18 kA. Once the molten pool is intact, the arc-stabilizing current is activated at 8 A. When 1 / 3 of the weight has been smelted, the smelting current is reduced from 18 kA to 16 kA. When the remaining 1 / 3 of the weight is melted for casting, the current is reduced by 4 kA for every 800 kg melted, resulting in a secondary ingot.

[0058] Step 3.3, Third Melting: Vacuuming is performed until the vacuum level inside the furnace reaches 4.2 × 10⁻⁶. -3 After torsion, smelting begins; the smelting process adopts a step-by-step current reduction method, with the smelting current between 6 and 16 kA; after the molten pool is well-established, the arc stabilizing current is turned on, with an arc stabilizing current value of 8 A; when 1 / 3 of the weight has been smelted, the smelting current is reduced from 16 kA to 12 kA, and when 100 kg remains, the current is reduced to 6 kA, resulting in a three-stage ingot.

[0059] In this comparative example, a TB6 titanium alloy ingot with a diameter of 750mm was finally obtained, and its elemental content distribution is shown in Table 5 below.

[0060] Table 5. Component content distribution in different parts of the TB6 titanium alloy ingot in Comparative Example 2

[0061] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for improving the compositional uniformity of large-size TB6 titanium alloy ingots, characterized in that, This method uses a three-stage vacuum consumable arc melting process to produce TB6 titanium alloy ingots. The first melting process includes: sealing the furnace after checking for any abnormalities, evacuating the vacuum, and then starting the melting process; the melting process adopts a step-by-step current reduction method, with the melting current between 3 and 18 kA; after the molten pool is intact, the arc stabilizing current is turned on, with the arc stabilizing current value being 44 to 46 A; when 1 / 3 of the weight has been melted, the melting current is reduced from 18 kA to 13 to 14 kA; when the remaining 1 / 3 of the weight of the ingot has been melted, the current is reduced by 2 kA for every 200 kg melted, resulting in a primary ingot; the two primary ingots are then welded together. The second melting process includes: melting begins after vacuuming; the melting process adopts a step-by-step current reduction method, with the melting current between 8 and 18 kA; after the molten pool is intact, the arc stabilizing current is turned on, with the arc stabilizing current value being 44 to 46 A; when 1 / 3 of the weight has been melted, the melting current is reduced from 18 kA to 15 to 16 kA; when the remaining 1 / 3 of the weight is melted for casting, the current is reduced by 4 kA for every 800 kg melted, resulting in a secondary ingot; The third melting process includes: melting begins after vacuuming; the melting process adopts a step-by-step current reduction method, with the melting current between 6 and 16 kA; after the molten pool is intact, the arc stabilizing current is turned on, with the arc stabilizing current value being 25 to 35 A; when 1 / 3 of the weight has been melted, the melting current is reduced from 16 kA to 12 kA, and when 100 kg remains, the current is reduced to 6 kA, resulting in a third ingot.

2. The method for improving the compositional uniformity of large-size TB6 titanium alloy ingots as described in claim 1, characterized in that, The vacuum level inside the furnace during the first melting process was 1.0 × 10⁻⁶. -2 ~1.5×10 -2 Torr.

3. The method for improving the compositional uniformity of large-size TB6 titanium alloy ingots as described in claim 1, characterized in that, The vacuum level inside the furnace during the second melting process was 4.0 × 10⁻⁶. -3 ~4.3×10 -3 Torr.

4. The method for improving the compositional uniformity of large-size TB6 titanium alloy ingots as described in claim 1, characterized in that, The vacuum level inside the furnace during the third melting process was 4.2 × 10⁻⁶. -3 ~4.5×10 -3 Torr.

5. The method for improving the compositional uniformity of large-size TB6 titanium alloy ingots as described in claim 1, characterized in that, The raw materials for TB6 titanium alloy ingots include sponge titanium, aluminum-vanadium-iron alloy, aluminum-vanadium alloy, aluminum granules, and titanium dioxide.

6. The method for improving the compositional uniformity of large-size TB6 titanium alloy ingots as described in claim 5, characterized in that, The mixing time for the raw materials is 2 to 5 minutes.

7. The method for improving the compositional uniformity of large-size TB6 titanium alloy ingots as described in claim 5, characterized in that, The process of preparing consumable electrodes includes: first, a small amount of sponge titanium pads are evenly arranged in the electrode block mold, and aluminum foil is placed on top of them. The mixed raw materials are added to the mold in batches and then pressed into several electrode blocks. The obtained electrode blocks are placed in a vacuum plasma welding box for welding to obtain consumable electrodes.

8. The method for improving the compositional uniformity of large-size TB6 titanium alloy ingots as described in claim 7, characterized in that, The mixed raw materials are added to the mold in four batches. The pressure for the first two batches is 2500t, and the pressure for the last two batches is 8000t.

9. The method for improving the compositional uniformity of large-size TB6 titanium alloy ingots as described in claim 7, characterized in that, The current during electrode block and primary ingot welding is 500-600A.

10. The method for improving the compositional uniformity of large-size TB6 titanium alloy ingots as described in claim 1, characterized in that, The molten liquid obtained after melting is placed in a crucible for cooling for 7 to 10 hours. After solidification, it is demolded and removed from the furnace.

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