A single electron beam cold hearth melting method for high-quality titanium alloy ingot

Abstract

This invention discloses a method for single-stage electron beam cold hearth melting of high-quality titanium alloy ingots, belonging to the field of titanium alloy melting technology. The method includes: constructing a C-shaped refining zone using a refining lance and a holding lance with zoned control; one refining lance is divided into two sections covering the transverse refining zone, and another refining lance covers the longitudinal refining zone; two holding lances precisely cover the outer and inner circumferences of a circular crystallizer, respectively; and a slag-blocking plate is inclinedly installed between the transverse refining zone and the crystallization zone. This invention, through the heat distribution design of the C-shaped cold hearth refining zone combined with the powerful stirring of the crystallizer by an external magnetic field, effectively solves the problems of microscopic segregation and compositional inhomogeneity in single-stage EB melting. This allows the EB ingots produced by single-stage melting to fully match or even surpass traditional secondary or tertiary VAR melting ingots in terms of chemical composition uniformity and the removal of high and low density inclusions.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy smelting technology, and relates to the preparation of titanium alloy ingots, specifically to a method for single-pass electron beam cold hearth smelting of high-quality titanium alloy ingots. Background Technology

[0002] While titanium alloys are widely used in aerospace and medical fields due to their excellent specific strength, corrosion resistance, and high-temperature performance, their high manufacturing cost severely restricts their large-scale civilian application. Currently, the mainstream multi-stage vacuum arc remelting (VAR) or combined "electron beam cold hearth melting (EBCHM) + VAR" processes, although ensuring quality, suffer from significant drawbacks such as long production cycles, high energy consumption, low equipment utilization, and limited utilization of recycled materials. Traditional single-stage EBCHM technology, while offering advantages in impurity removal and raw material adaptability, suffers from poor ingot composition uniformity due to improper molten pool flow control and difficulty in controlling element volatilization, making it difficult to meet the high standards required for critical components. Therefore, developing a short-cycle, low-energy-consumption, high-quality, and low-cost single-stage electron beam cold hearth melting technology that can efficiently utilize recycled materials and achieve or even surpass the quality levels of traditional multi-stage melting in a single melting process has become a critical challenge that urgently needs to be overcome. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a method for single-stage electron beam cold-bed melting of high-quality titanium alloy ingots, thereby solving the technical problems of poor ingot composition uniformity, long production cycle, high energy consumption, and low utilization rate of recycled materials in traditional multi-stage melting processes.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for single-stage electron beam cold hearth melting of high-quality titanium alloy ingots, the specific steps of which are as follows: Step 1, Raw material selection: Weigh the raw materials according to the target composition of the titanium alloy ingot.

[0005] Step 2, Loading: Load the raw materials prepared in Step 1 into the electron beam melting furnace.

[0006] Step 3, evacuation and gun start-up: After the material is loaded into the furnace, the furnace door is closed and evacuation is carried out until the vacuum level meets the gun start-up conditions; then the electron guns are started in sequence until the current of all electron guns is stable.

[0007] Step 4, material melting: The material is pushed into the melting zone; the four raw material melting guns above the melting zone are responsible for melting the material, and their electron beam spots are distributed in the upper and lower positions on the left and right sides of the melting cooling bed.

[0008] Step 5, material refining: The raw material melting gun separates the material into a second shape and focuses on the melting zone for refining.

[0009] Step 6, material refining: Construct a C-shaped refining zone using refining guns and heat-preserving guns for zoned control; one refining gun covers the horizontal refining zone with two images, and the other refining gun covers the vertical refining zone; two heat-preserving guns precisely cover the outer and inner circles of the circular crystallizer respectively; a slag baffle is added between the horizontal refining zone and the crystallization zone, and the slag baffle is set at an angle.

[0010] Step 7, Pulling and Magnetic Stirring: When the liquid level of the material in the crystallizer reaches the pulling line, pulling begins; a magnetic field is applied simultaneously during pulling.

[0011] Step 8, Ingot Feeding: At the end of the smelting process, the shallow molten pool characteristics of the electron beam are utilized to rapidly reduce the current of the holding gun and gradually shrink the scanning pattern for rapid feeding.

[0012] The present invention also has the following technical features: Specifically and optionally, in step one, the titanium alloy ingot is a TC4 titanium alloy ingot, the raw materials of which are 75 wt% TC4 alloy recycled blocks and 25 wt% sponge titanium and intermediate alloy.

[0013] Specifically and optionally, in step one, the titanium alloy ingot is a TA15 titanium alloy ingot, the raw materials of which are 70 wt% TA15 titanium alloy recycled scrap and 30 wt% sponge titanium and intermediate alloy.

[0014] Specifically and optionally, when preparing TC4 titanium alloy ingots, the specific process of step two is as follows: after weighing and mixing the sponge titanium and the intermediate alloy, press them into square thin blocks of 90*90*70mm; lay the square thin blocks in sequence at the bottom of the electron beam melting furnace hopper, and neatly stack the TC4 titanium alloy recycled blocks on top to complete the loading.

[0015] Specifically and optionally, when preparing TA15 titanium alloy ingots, the specific process of step two is as follows: weigh and mix the TA15 titanium alloy recycled scrap with sponge titanium and intermediate alloy raw materials, and then press them into small single-weight round cakes with a single cake weight of 2.0 kg and a density of 3.1 g / cm³ after pressing; place the pressed cakes into the electron beam melting furnace hopper in sequence to complete the loading.

[0016] Specifically, in step three, the vacuum level is 1.5 Pa, and the leak detection rate is 0.62–0.8 Pa / min.

[0017] Specifically, in step three, based on functional classification, the electron gun includes a raw material melting gun (guns 1 to 4), a refining gun (guns 5 and 6), and a heat preservation gun (guns 7 and 8).

[0018] Specifically, in step three, the current of the raw material melting gun and refining gun is stabilized at 6A, and the current of the heat preservation gun is stabilized at 0.5A.

[0019] Specifically, in step four, the material is pushed into the melting zone at a speed of 7.3–9.0 mm / min.

[0020] Specifically, in step four, the distance between the two electron guns facing each other in the raw material melting gun is set to 280-300 mm.

[0021] Specifically and optionally, when preparing TC4 titanium alloy ingots, in step five, the power distribution ratio of each raw material melting gun for melting and roughing is 9:1; the current of the raw material melting gun is 9.0 to 10.0 A, and the melting speed is controlled at 850 to 950 kg / h.

[0022] Specifically and optionally, when preparing TA15 titanium alloy ingots, in step five, the power distribution ratio of each raw material melting gun for melting and roughing is 6:1; the current of two raw material melting guns is 9.1 to 10.1 A, and the current of the other two raw material melting guns is 8.7 to 9.7 A; the melting speed is controlled at 850 to 950 kg / h.

[0023] Specifically and optionally, when preparing TC4 titanium alloy ingots, in step six, the current of the refining gun covering the transverse refining zone is 7.3–8.3A, with a power distribution ratio of 6:4; the current of the refining gun covering the longitudinal refining zone is 7.3–8.3A; the current of the heat-preserving gun covering the outer circle of the crystallizer is 6.5–7.5A; and the current of the heat-preserving gun covering the inner circle of the crystallizer is 7.5–8.5A.

[0024] Specifically and optionally, when preparing TA15 titanium alloy ingots, in step six, the current of the refining gun covering the transverse refining zone is 7.5–8.5A, with a power distribution ratio of 6:4; the current of the refining gun covering the longitudinal refining zone is 7.5–8.5A; the current of the heat-preserving gun covering the outer circle of the crystallizer is 6.5–7.5A; and the current of the heat-preserving gun covering the inner circle of the crystallizer is 7.5–8.5A.

[0025] Specifically, in step six, the slag baffle is made of water-cooled copper, with a wire mesh covering the surface, and its dimensions are 450mm×40mm×120mm (length×width×height).

[0026] Specifically, in step six, the tilt angle of the slag baffle is 15°.

[0027] Specifically, in step seven, the conditions for pulling the spindle are: the pulling speed is 8.0 to 8.3 mm / min, and the pulling lever reciprocates in a cycle of "three down and one up".

[0028] Specifically, in step seven, the coil voltage used to apply the magnetic field is 12-15V, and the magnetic field frequency is 30-50Hz.

[0029] Specifically, in step eight, the compensation time is 20-25 minutes.

[0030] The beneficial technical effects of this invention compared to the prior art are as follows: (I) This invention effectively solves the problems of microsegregation and compositional inhomogeneity in single EB melting by designing the heat distribution of the “C”-shaped cold bed refining zone and combining it with the strong stirring of the external magnetic field of the crystallizer. This makes the EB ingots produced by single melting comparable to or even better than traditional secondary or tertiary VAR melting ingots in terms of chemical composition uniformity and removal of high and low density inclusions.

[0031] (II) This invention achieves rapid production in the smelting process by employing a high-current, high-melting-rate roughing process, combined with a shortened feeding time. Compared to the traditional multi-stage smelting process combining electron beam cold hearth furnace smelting and vacuum consumable arc furnace smelting (EB+VAR), the production efficiency of this invention is increased by more than 60%.

[0032] (III) On the one hand, this invention allows for the addition of a high proportion of recycled scrap and slabs to the raw materials, significantly reducing raw material costs; on the other hand, by replacing multiple smelting processes with a single smelting process, the process flow is simplified, and equipment usage and maintenance costs are reduced. Overall energy consumption is reduced by 40% compared to multiple smelting processes.

[0033] (IV) By setting an inclined water-cooled copper slag baffle plate and covering it with wire mesh, the present invention effectively isolates the splashes in the smelting zone, prevents them from entering the crystallizer and contaminating the ingot, and ensures process stability and product purity. Attached Figure Description

[0034] Figure 1 This is a flowchart of a single electron beam cold bed melting process for titanium alloys.

[0035] Figure 2 This is a schematic diagram of the electron gun and cooling bed layout.

[0036] Figure 3 It is used for electron beam melting cooling beds and crystallizers.

[0037] Figure 4 It is used for electron beam cold bed melting and solidification of the shell.

[0038] Figure 5 Add an external stirring coil to the crystallizer.

[0039] Figure 6 A schematic diagram of multi-point sampling for electron beam cold hearth melting of ingots.

[0040] Figure 7This is a comparison of the uniformity of chemical composition of ingots in Example 1 and Comparative Example 1.

[0041] The technical solution of the present invention will be further described below with reference to the embodiments. Detailed Implementation

[0042] It should be noted that, unless otherwise specified, all raw materials and equipment used in this invention are those known in the art.

[0043] 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.

[0044] Example 1 This embodiment provides a method for single-stage electron beam cold hearth melting of high-quality titanium alloy ingots, the specific steps of which are as follows: Step 1, Raw material selection: Weigh the raw materials according to the target composition of the titanium alloy ingot, which includes 75% TC4 alloy recycled blocks (block size 30-80mm, with surface oxide scale removed by shot blasting and grinding) and 25% sponge titanium and aluminum-vanadium master alloy, ensuring that the Al and V element content meets the TC4 composition requirements.

[0045] Step 2, loading: Weigh and mix the sponge titanium and intermediate alloy, then press them into 90*90*70mm square thin blocks; place the pressed blocks in sequence at the bottom of the EB silo, and neatly stack TC4 titanium alloy recycled blocks on top to complete the loading, ensuring uniform force distribution during melting and pushing, and preventing material jamming.

[0046] Step 3, evacuation and gun start-up: After the material is loaded into the furnace, the furnace door is closed and evacuation is performed. When the vacuum degree of the furnace chamber reaches 1.5Pa, a leak test is performed. The leak rate is 0.8Pa / min, which meets the conditions for gun start-up. Electron guns 1-8 are started in sequence, and the current of electron guns 1-6 is gradually stabilized at 6A, and the current of electron guns 7-8 is stabilized at 0.5A.

[0047] Step 4, Material Melting: Activate the pusher plate to push the material into the melting zone at a speed of 8.5±0.5 mm / min. Electron guns #1-4 above the melting zone are responsible for melting the material, with their electron beam spots distributed on the left and right sides and above and below the melting cooling bed, respectively. The distance between the beam spots of the two opposing electron guns #1-4 is set to 280 mm to avoid mutual attraction between the beams and to expand the melting zone.

[0048] Step 5, material roughing: Electron guns #1-4 separate the material into a second pattern and focus it on the melting zone for roughing. The power distribution ratio of each electron gun for melting and roughing is 9:1, with the current of electron guns #1-4 being 9.5±0.5A, and the melting speed controlled at 900±50kg / h. High current and high melting speed operation improve melting efficiency, and high temperature promotes impurity volatilization and inclusion flotation.

[0049] Step Six, Material Refining: A "C"-shaped refining zone is constructed using electron guns #5-#8 for zoned control. Electron gun #5 covers the horizontal refining zone with two images, a current of 7.8±0.5A, and a power distribution ratio of 6:4. Electron gun #6 covers the vertical refining zone with a current of 7.8±0.5A. Electron guns #7 and #8 precisely cover the outer and inner circumferences of the circular crystallizer, respectively, with currents of 7#: 7.0±0.5A and 8#: 8.0±0.5A.

[0050] A water-cooled copper slag baffle plate with an inclination of 15° is added between the horizontal refining zone and the crystallization zone. The plate measures 450mm in length, 40mm in width, and 120mm in height, and is covered with wire mesh to effectively intercept splashed titanium slag and any condensate that may fall.

[0051] Step 7, Ingot Pulling and Magnetic Stirring: When the material level in the crystallizer reaches the ingot pulling line, the ingot pulling mechanism and external magnetic field stirring system are simultaneously activated. The ingot pulling speed is set to 8.0 mm / min, and the ingot pulling lever reciprocates in a "three down, up" cycle to improve the surface quality of the ingot. At the same time, the hexagonal magnetic field coil outside the crystallizer is activated, with a magnetic field frequency of 50 Hz and a coil voltage of 12 V, promoting convection in the melt and achieving thorough homogenization of the liquid within the crystallizer.

[0052] Step 8, Ingot Feeding: At the end of the smelting process, the shallow molten pool characteristics of the electron beam are utilized to rapidly reduce the current of electron guns #7 and #8 and gradually shrink the scanning pattern for rapid feeding. The feeding time is 20 minutes, which effectively ensures the uniformity of the composition at the end of the ingot.

[0053] Verification of the effect in Example 1: Sampling and testing were performed on a Φ750mm finished ingot. Samples were taken from the head, upper, middle, lower, and tail sections along the length of the ingot, and 13 points were taken from the cross-sections at the head and tail for compositional homogeneity analysis. The results showed that the Al content deviation was 0.21%, the V content deviation was 0.13%, the O content deviation was 0.027%, and the Fe content deviation was 0.023%, all of which were better than the requirements of GB / T 3620.1 standard. Specific results are shown in Tables 1 and 2.

[0054] Table 1. Element content determination results of different sampling locations of the finished ingots obtained in Example 1.

[0055] Table 2. Element content determination results at different sampling points of the finished ingots prepared in Example 1.

[0056] Example 2: This embodiment provides a method for single-stage electron beam cold hearth melting of high-quality titanium alloy ingots, the specific steps of which are as follows: Step 1, Raw material selection: Weigh the raw materials according to the target composition of the titanium alloy ingot, which includes 70% TA15 titanium alloy recycled scrap (after degreasing, drying and sorting pretreatment) and 30% sponge titanium and intermediate alloys such as MoAl and VAl, to ensure that the content of elements such as Al, Zr, Mo and V meets the standard requirements of TA15 titanium alloy.

[0057] Step 2, Loading: The recycled scrap is weighed and mixed with raw materials such as sponge titanium and master alloy, and then pressed into small, round cakes with a single cake weighing 2.0 kg and a density of 3.1 g / cm³ after pressing. The pressed cakes are then placed sequentially into the EB hopper to complete the loading process, ensuring smooth material feeding during the melting process.

[0058] Step 3, Evacuation and Gun Start-up: After the material is loaded into the furnace, the furnace door is closed and evacuation is performed. When the vacuum level in the furnace chamber reaches 1.5 Pa, a leak test is conducted. If the leak rate is confirmed to be 0.62 Pa / min, which meets the gun start-up requirements, electron guns 1-8 are started sequentially. The current of electron guns 1-6 is gradually stabilized at 6 A, and the current of electron guns 7-8 is stabilized at 0.5 A.

[0059] Step 4, Material Melting: Activate the pusher plate to push the material into the melting zone at a speed of 7.8±0.5mm / min. Electron guns #1-4 are responsible for material melting, and the beam spacing between the two opposing electron guns is set to ≥300mm.

[0060] Step 5, material roughing: Electron guns #1-4 separate the second pattern and focus on the melting zone for roughing. The power distribution ratio of each electron gun for melting and roughing is 6:1. The current of electron guns #1 and #2 is 9.6±0.5A, and the current of electron guns #3 and #4 is 9.2±0.5A. The melting speed is controlled at 900±50kg / h.

[0061] Step Six, Material Refining: Construct a "C"-shaped refining zone using zoned control of electron guns #5-#8. Electron gun #5 current is 8.0±0.5A (power distribution ratio 6:4), electron gun #6 current is 8.0±0.5A, and electron gun #7 and #8 currents are 7.0±0.5A and 8.0±0.5A respectively.

[0062] A water-cooled copper slag baffle plate with an inclination of 15° is added between the horizontal refining zone and the crystallization zone. The plate has dimensions of 450mm in length, 40mm in width, and 120mm in height, and its surface is covered with wire mesh.

[0063] Step 7, Pulling and Magnetic Stirring: Pulling speed is 8.3 mm / min, and the pulling lever reciprocates in a "three down, up" cycle. Turn on the hexagonal magnetic field coil, set the magnetic field frequency to 30 Hz, and the coil voltage to 15 V to induce forced convection in the melt.

[0064] Step 8, Ingot Feeding: Quickly reduce the current of electron guns #7 and #8 and gradually shrink the scanning pattern to perform rapid feeding. The feeding time should be controlled within 25 minutes.

[0065] Verification of the effect in Example 2: Sampling and testing were performed on a Φ750mm finished ingot. Samples were taken along the length of the ingot at the head, upper, middle, lower, and tail sections, and 13 points were taken at the head and tail cross-sections for compositional homogeneity analysis. The results showed that the Al content deviation was 0.26%, V content deviation was 0.18%, Mo content deviation was 0.17%, Zr content deviation was 0.18%, and O content deviation was 0.018%, all of which were better than the requirements of GB / T 3620.1 standard. Specific results are shown in Tables 3 and 4.

[0066] Table 3. Element content determination results of different sampling parts of the finished ingots obtained in Example 2.

[0067] Table 4. Element content determination results at different sampling points of the finished ingots prepared in Example 2.

[0068] Comparative Example 1: This comparative example presents a method for a normal single-batch EB melting of TC4 ingots. It employs a conventional single-batch melting process using seven electron beam cold guns and a short, straight cooling bed, without utilizing the "C"-shaped refining zone optimization design and external magnetic field stirring technology of this invention. The specific steps are as follows: Step 1, Raw material selection: Same as the chemical composition ratio and raw materials in Example 1.

[0069] Step 2, Loading: Same as the furnace preparation steps in Example 1.

[0070] Step 3, Evacuation and Gun Start-up: After loading the furnace, evacuate to a vacuum level of 1.5 Pa. After the leak test is passed, start the electron gun.

[0071] Step four, material melting and smelting: Conventional smelting parameters were used, and the high-current, high-melting-rate roughing process described in this invention was not employed. The smelting speed was controlled at 700–800 kg / h. Electron guns #1-4 were used only for material melting and were not used to separate a second pattern for roughing.

[0072] Step 5, material refining: Electron guns #5-7 use conventional scanning trajectories, do not construct a "C"-shaped refining zone, and do not install slag baffles between the transverse refining zone and the crystallization zone.

[0073] Step Six, Pulling and Feeding: The external magnetic field stirring of the crystallizer is not activated; melt mixing relies solely on the natural flow of the liquid. Feeding is performed using a conventional slow feeding process, with a feeding time of approximately 40 minutes.

[0074] Verification of the effect of Comparative Example 1: Samples of the finished ingots were taken for testing. The results showed that the Al content of the ingots deviated by 0.45%, the V content by 0.25%, the O content by 0.048%, and the Fe content by 0.043%, indicating obvious compositional inhomogeneity. This method is only suitable for civilian non-critical components with low uniformity requirements. Specific results are shown in Tables 5 and 6.

[0075] Table 5. Element content determination results of different sampling locations of the finished ingots obtained in Comparative Example 1.

[0076] Table 6. Element content determination results at different sampling points of the finished ingots prepared in Comparative Example 1.

[0077] Comparative Example 2: This comparative example presents a method for preparing TC4 ingots. This method uses a traditional combined process of "electron beam cold hearth melting (EBCHM) + one-stage vacuum arc remelting (VAR)" to produce TC4 ingots. The specific steps are as follows: Step 1, Raw material selection: Same as the chemical composition ratio and raw materials in Example 1.

[0078] Step 2, First Melting (EBCHM): The above raw materials are melted into a primary ingot (Φ750mm) using a conventional electron beam cold bed melting process. The "C"-shaped refining zone, slag baffle, and magnetic stirring features of this invention are not employed during the melting process.

[0079] Step 3, Secondary Remelting (VAR): The primary ingot obtained from EBCHM is used as a consumable electrode for secondary remelting in a vacuum consumable arc furnace. The remelting current is controlled at 20-28kA, and the arc-stabilizing magnetic field stirring frequency is 20-40Hz, ultimately yielding a finished ingot with a diameter of 820mm.

[0080] Step 4, Production Cycle and Energy Consumption: The entire production process includes two independent smelting steps, requiring two complete processes such as furnace loading, evacuation, smelting, and cooling to unload the ingots. The production cycle is approximately 2.2 times that of Example 1. The overall energy consumption (electricity consumption + water consumption + equipment depreciation) is approximately 2.6 times that of Example 1.

[0081] Step 5, Ingot Inspection: Samples of the finished ingots were taken for testing. The results showed that the Al content deviation was 0.20%, the V content deviation was 0.18%, the Fe content deviation was 0.038%, and the O content deviation was 0.031%. The ingot composition meets the requirements of the aerospace-grade TC4 material standard.

[0082] Verification of the effect of Comparative Example 2: The ingot quality level of Comparative Example 2 is basically the same as that of Example 1, but it requires additional VAR melting, so the production cycle is longer and the overall cost is higher.

Claims

1. A method for single-stage electron beam cold hearth melting of high-quality titanium alloy ingots, characterized in that, The specific steps are as follows: Step 1, Raw material selection: Weigh the raw materials according to the target composition of the titanium alloy ingot; Step 2, Loading: Load the raw materials prepared in Step 1 into the electron beam cold hearth melting furnace; Step 3, evacuation and gun start-up: After the material is loaded into the furnace, the furnace door is closed and evacuation is carried out until the vacuum level meets the gun start-up conditions; then the electron guns are started sequentially until the current of all electron guns is stable; the electron guns include the raw material melting gun, the refining gun, and the heat preservation gun; Step 4, Material melting: Push the material into the melting zone; the raw material melting gun above the melting zone is responsible for melting the material, and its electron beam spots are distributed on the left and right sides and the top and bottom of the melting cooling bed. Step 5, material refining: The raw material melting gun separates the material into a second shape and focuses on the melting zone for refining; Step 6, material refining: Construct a C-shaped refining zone using refining guns and heat-preserving guns for zoned control; one refining gun is divided into two images covering the horizontal refining zone, and the other refining gun covers the vertical refining zone; the two heat-preserving guns precisely cover the outer and inner circles of the circular crystallizer respectively; a slag baffle is added between the horizontal refining zone and the crystallization zone, and the slag baffle is set at an angle. Step 7, Pulling and Magnetic Stirring: When the liquid level of the material in the crystallizer reaches the pulling line, pulling begins; a magnetic field is applied simultaneously during pulling. Step 8, Ingot Feeding: At the end of the smelting process, the shallow molten pool characteristics of the electron beam are utilized to rapidly reduce the current of the holding gun and gradually shrink the scanning pattern for rapid feeding.

2. The method for single-stage electron beam cold hearth melting of high-quality titanium alloy ingots as described in claim 1, characterized in that, In step one, the titanium alloy ingot is a TC4 titanium alloy ingot or a TA15 titanium alloy ingot.

3. The method for single-stage electron beam cold hearth melting of high-quality titanium alloy ingots as described in claim 1, characterized in that, In step three, the vacuum level is 1.5 Pa, and the leak detection rate is 0.62–0.8 Pa / min.

4. The method for single-stage electron beam cold hearth melting of high-quality titanium alloy ingots as described in claim 1, characterized in that, In step three, the current of the raw material melting gun and refining gun is stabilized at 6A, and the current of the heat preservation gun is stabilized at 0.5A.

5. The method for single-stage electron beam cold hearth melting of high-quality titanium alloy ingots as described in claim 2, characterized in that, When preparing TC4 titanium alloy ingots: In step five, the power distribution ratio between smelting and roughing in each raw material smelting lance is 9:1; the current of the raw material smelting lance is 9.0 to 10.0 A, and the smelting speed is controlled at 850 to 950 kg / h. In step six, the current of the refining gun covering the horizontal refining zone is 7.3–8.3A, with a power distribution ratio of 6:4; the current of the refining gun covering the vertical refining zone is 7.3–8.3A; the current of the heat-preserving gun covering the outer circle of the crystallizer is 6.5–7.5A; and the current of the heat-preserving gun covering the inner circle of the crystallizer is 7.5–8.5A.

6. The method for single-stage electron beam cold hearth melting of high-quality titanium alloy ingots as described in claim 2, characterized in that, When preparing TA15 titanium alloy ingots: In step five, the power distribution ratio between smelting and roughing in each raw material smelting lance is 6:1; the current of two raw material smelting lances is 9.1 to 10.1 A, and the current of the other two raw material smelting lances is 8.7 to 9.7 A; the smelting speed is controlled at 850 to 950 kg / h. In step six, the current of the refining gun covering the horizontal refining zone is 7.5–8.5A, with a power distribution ratio of 6:4; the current of the refining gun covering the vertical refining zone is 7.5–8.5A; the current of the heat-preserving gun covering the outer circle of the crystallizer is 6.5–7.5A; and the current of the heat-preserving gun covering the inner circle of the crystallizer is 7.5–8.5A.

7. The method for single-stage electron beam cold hearth melting of high-quality titanium alloy ingots as described in claim 1, characterized in that, In step six, the slag baffle is made of water-cooled copper and covered with iron wire; the slag baffle is tilted at an angle of 15°.

8. The method for single-stage electron beam cold hearth melting of high-quality titanium alloy ingots as described in claim 1, characterized in that, In step seven, the drawing speed is 8.0–8.3 mm / min.

9. The method for single-stage electron beam cold hearth melting of high-quality titanium alloy ingots as described in claim 1, characterized in that, In step seven, the coil voltage used to apply the magnetic field is 12–15V, and the magnetic field frequency is 30–50Hz.

10. The method for single-stage electron beam cold hearth melting of high-quality titanium alloy ingots as described in claim 1, characterized in that, In step eight, the compensation time is 20-25 minutes.

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