Method for preparing titanium alloy flat ingot by duplexing vacuum consumable skull melting furnace and electron beam cold hearth furnace

Abstract

The invention discloses a method for preparing titanium alloy flat ingots by the combination of a vacuum consumable skull melting furnace and an electron beam cold hearth furnace. By using a large proportion of TC4 return materials and adopting the combination process of a vacuum consumable skull melting furnace + an electron beam cold hearth furnace, titanium alloy flat ingots with high stability and suitable for direct rolling are prepared. The invention effectively reduces carbon emissions and production costs from the aspects of raw materials and preparation processes, and helps to realize the recycling of titanium resources and the short-process preparation of titanium alloys.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium alloy ingot melting, and particularly to a method for preparing titanium alloy flat ingots by duplexing a vacuum consumable skull melting furnace and an electron beam cold hearth furnace. Background Art

[0002] Titanium alloys are widely used in industries such as aerospace, ocean engineering, petrochemical, and biomedical due to their excellent comprehensive properties such as low density, high specific strength, high corrosion resistance, and non-magnetism. At present, the specifications of titanium materials in China are small, the cost is high, and the performance is insufficient. In order to promote the development of the titanium alloy industry, it is necessary to improve the preparation technology of low-cost and high-performance titanium and titanium alloys.

[0003] TC4 titanium alloy has excellent mechanical properties and corrosion resistance, and is widely used in fields such as aerospace and petrochemical; however, due to the high hardness and difficult processing of TC4, its production cost is relatively high. Therefore, by reasonably recycling and reusing TC4 titanium alloys from different sources, not only can the production cost of titanium alloys be reduced and the resource utilization efficiency be improved, but it also helps to reduce environmental pollution and achieve sustainable development.

[0004] Both the vacuum consumable skull melting furnace and the electron beam cold hearth furnace can effectively remove high- and low-density inclusions to obtain high-purity titanium alloys; currently, titanium and titanium alloys are often produced by vacuum consumable melting, but its refining and impurity removal and composition homogenization degrees are limited, and 2-3 times of melting are required, which affects the application of titanium material products; while the electron beam cold hearth furnace has fewer processes and a high yield, and can produce titanium alloys of different shapes and specifications, but it is easy to cause element burning loss.

[0005] Therefore, there is an urgent need to study a method for preparing titanium alloys at low cost using TC4 return materials. Summary of the Invention

[0006] Aiming at the defects existing in the prior art, the purpose of the present invention is to provide a method for preparing titanium alloy flat ingots by duplexing a vacuum consumable skull melting furnace and an electron beam cold hearth furnace. By using a large proportion of TC4 return materials and adopting the duplex process of vacuum consumable skull melting furnace + electron beam cold hearth furnace, high-stability titanium alloy flat ingots that can be directly rolled are prepared. The present invention effectively reduces carbon emissions and production costs from the aspects of raw materials and preparation processes, and helps to realize the circular reuse of titanium resources and the short-process preparation of titanium alloys.

[0007] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for preparing titanium alloy flat ingots by duplexing a vacuum consumable skull melting furnace and an electron beam cold hearth furnace, including the following steps:

[0009] S1, confirming the composition of TC4 return material, and mixing TC4 return material with aluminum beans, ferrochrome and metallic chromium according to the target composition of titanium alloy slab;

[0010] S2, the TC4 return material is divided into two parts, one part of the TC4 return material is made into a consumable electrode and welded with the auxiliary electrode of the solidification furnace, and the remaining TC4 return material is placed at the bottom of the crucible of the solidification furnace as an arc starting pad, and aluminum beans, ferrochrome alloy and metal chromium are used as the bottom material of the solidification furnace;

[0011] S3, sealing the shell furnace and performing vacuum treatment;

[0012] S4, shell furnace casting, control the melting current and arc distance in the arc starting stage to form a stable discharge arc; control the melting current and time in the smelting stage, and use a large current to melt to a predetermined weight after the molten pool covers the bottom of the crucible, and then inject the titanium liquid into the mold and cool it to obtain the shell furnace casting;

[0013] S5, after the surface of the ingot in the solidification furnace is milled and turned, the composition is tested. If the composition meets the internal control requirements, the process proceeds to S6;

[0014] S6, sawing the ingots in the solidification furnace into blocks as solidification materials, placing them into the left and right boxes of the electron beam cooling bed charge, sealing the electron beam cooling bed furnace, and performing vacuuming and leak detection;

[0015] S7, confirming the graphic position of each electron gun in the electron beam cooling bed;

[0016] S8, after the pattern position of the electron gun is confirmed, the power of the 5# electron gun, the 4# electron gun, the 3# electron gun, the 2# electron gun, and the 1# electron gun is increased to 120-150kW to heat and melt the solidified crust material in the cooling bed;

[0017] S9, start the feeding system, push the condensed shell material into the melting zone, 1# electron gun, 2# electron gun, 3# electron gun and 4# electron gun melt the condensed shell material, after the melted titanium liquid flows into the refining zone, 5# electron gun refines the titanium liquid, the refined titanium liquid overflows into the crystallizer in the crystallization zone, 6# electron gun and 7# electron gun are turned on to heat the titanium liquid, when the titanium liquid covers the bottom of the crystallizer, the graphic positions of 6# electron gun and 7# electron gun cover the entire crystallizer and increase the power to heat the titanium liquid, until the titanium liquid fills the crystallizer and starts to pull the ingot;

[0018] S10, after the melting and casting is completed, the tail of the ingot is subjected to shrinkage compensation, and after the shrinkage compensation is completed, the ingot is cooled. After cooling, the electron beam cooling furnace is opened to take out the titanium alloy flat ingot from the crystallizer.

[0019] Preferably, in step S1:

[0020] The target composition of the titanium alloy ingot is as follows by mass percentage: Al: 6.90 - 7.25%, V: 3.90 - 4.10%, Cr: 1.50 - 1.65%, Fe: 0.90 - 1.10%, and the balance is Ti and unavoidable impurities;

[0021] The addition amount of the TC4 return material is 50 - 80%.

[0022] Preferably, in step S2, the weight of the TC4 return material used for the consumable electrode is 92% - 95% of the total amount of the TC4 return material.

[0023] Preferably, in step S3, after vacuum pumping, the vacuum degree in the skull furnace reaches below 1.5 Pa.

[0024] Preferably, in step S4:

[0025] In the arc starting stage, the melting current is 1.3 - 1.7 kA, and the arc distance of the arc is 10 - 40 mm;

[0026] In the melting stage, the melting current is gradually increased to 10 - 15 kA. After the molten pool covers the bottom of the crucible, the melting current is uniformly increased from 10 - 15 kA to 30 - 35 kA within 1 - 2 minutes;

[0027] The mold uses a graphite barrel - shaped mold.

[0028] Preferably, in step S5, during the composition detection process, if the composition of the skull furnace ingot meets the following internal control requirements: 6.7% - 7.5% Al, 3.4% - 4.3% V, 1.1% - 1.9% Cr, 0.6% - 1.3% Fe, O ≤ 0.20%, H ≤ 0.015%, N ≤ 0.05%, C ≤ 0.08%, then enter S6; otherwise, alloy compensation is carried out in the form of adding alloys according to the detection results of the skull furnace ingot until the composition meets the internal control requirements and then enter S6.

[0029] Preferably, in step S6, the electron beam cold hearth furnace is evacuated to ≤ 8×10 -3 Torr, and when leak - checking, ensure that the leak rate of the electron beam cold hearth furnace is ≤ 5 Torr·L / S.

[0030] Preferably, in step S7, during the graphic position confirmation process, if the graphic positions of all electron guns are accurate, then enter S8; otherwise, the electron guns with graphic position errors are adjusted until the graphic positions of all electron guns are accurate and then enter S8.

[0031] Preferably, in step S9:

[0032] When melting the skull material, the powers of the 1# electron gun, 2# electron gun, 3# electron gun and 4# electron gun are 150 - 240 kW;

[0033] When refining the titanium liquid, the power of the 5# electron gun is 100 - 130 kW;

[0034] Before the titanium liquid covers the bottom of the crystallizer, the powers of the 6# electron gun and 7# electron gun are 240 - 300 kW;

[0035] During the melting and casting process, adjust the powers of each electron gun to ensure that the melting speed of the skull material matches the ingot pulling speed;

[0036] During the ingot pulling process, the ingot pulling speed is controlled at 200 ± 50 mm / h, and the liquid level height in the crystallizer is controlled at 5 - 10 mm from the edge of the crystallizer.

[0037] Preferably, during the melting and casting process, the powers of the 1# electron gun, 2# electron gun, 3# electron gun and 4# electron gun are 210 - 300 kW, the power of the 5# electron gun is 120 - 150 kW, and the powers of the 6# electron gun and 7# electron gun are 200 - 250 kW.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] 1. The present invention recycles a large proportion of TC4 return materials, which can not only reduce the production cost of titanium alloys and improve the resource utilization efficiency, but also reduce environmental pollution and achieve sustainable development;

[0040] 2. The present invention adopts the double melting and casting process of vacuum consumable skull furnace + electron beam cold hearth furnace, which can effectively reduce element burn - out, remove high - and low - density inclusions, obtain high - purity titanium alloys. At the same time, it can use TC4 return materials to melt and cast directly rollable titanium alloy flat ingots, which helps to reduce carbon emissions and production costs, and realize the circular reuse of titanium resources and the short - process preparation technology of titanium alloys. Description of the Drawings

[0041] Figure 1 It is the flow chart of the method for preparing titanium alloy flat ingots by double melting of vacuum consumable skull furnace and electron beam cold hearth furnace in the present invention;

[0042] Figure 2 It is the distribution diagram of the electron gun scanning area in the electron beam cold hearth furnace of the present invention;

[0043] Among them, 1. Scanning area of 1# electron gun, 2. Scanning area of 2# electron gun, 3. Scanning area of 3# electron gun; 4. Scanning area of 4# electron gun, 5. Scanning area of 5# electron gun, 6. Scanning area of 6# electron gun, 7. Scanning area of 7# electron gun; 8. Cold hearth, 9. Crystallizer. DETAILED DESCRIPTION

[0044] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form.

[0045] Combination Figure 1 , Figure 2 As shown, the present invention provides a method for preparing titanium alloy flat ingots by using a vacuum consumable shell furnace and an electron beam cooling hearth furnace in combination, comprising the following steps:

[0046] S1, confirming the composition of TC4 return material, and mixing TC4 return material with aluminum beans, ferrochrome and metallic chromium according to the target composition of titanium alloy slab;

[0047] This step is mainly about batching. TC4 return material, aluminum beans, ferrochrome and metal chromium are selected as raw materials. First, the composition of TC4 return material, especially the mass percentage of aluminum and vanadium, is confirmed, and the materials are batched according to the target composition of titanium alloy slab, where the target composition of titanium alloy slab is as follows by mass percentage: Al: 6.90~7.25%, V: 3.90~4.10%, Cr: 1.50~1.65%, Fe: 0.90~1.10%, and the balance is Ti and unavoidable impurities. When batching, ensure that the amount of TC4 return material added is 50~80% of the total raw material.

[0048] S2, the TC4 return material is divided into two parts, one part of the TC4 return material is made into a consumable electrode and welded with the auxiliary electrode of the solidification furnace, and the remaining TC4 return material is placed at the bottom of the crucible of the solidification furnace as an arc starting pad, and aluminum beans, ferrochrome alloy and metal chromium are used as the bottom material of the solidification furnace;

[0049] This step is mainly about the crust furnace distribution. The TC4 return material is divided into two parts. One part of the TC4 return material is made into a consumable electrode and welded to the auxiliary electrode of the crust furnace. The consumable electrode is installed directly above the crucible in the crust furnace to ensure that the electrode and the crucible are in good contact. The remaining TC4 return material is placed at the bottom of the crucible of the crust furnace as an arc-starting bottom pad, and aluminum beans, ferrochrome and metallic chromium are used as the crust furnace bottom material. Among them, the weight of the TC4 return material used for the consumable electrode is 92%~95% of the total amount of TC4 return material, and the weight of the TC4 return material used for the arc-starting bottom pad is 5%~8% of the total amount of TC4 return material.

[0050] S3, sealing the shell furnace and performing vacuum treatment;

[0051] In this step, the vacuum degree in the shell solidification furnace is ensured to be below 1.5 Pa through vacuum treatment.

[0052] S4. Consumable-electrode skull melting casting: During the arc starting stage, control the melting current and arc distance to form a stable discharge arc; during the melting stage, control the melting current and time. After the molten pool covers the bottom of the crucible, conduct high-current melting until the predetermined weight is reached, and then inject the titanium liquid into the mold for cooling to obtain a consumable-electrode skull melting casting blank.

[0053] This step is consumable-electrode skull melting casting, including an arc starting stage and a melting stage.

[0054] During the arc starting stage, control the melting current and arc distance to form a stable discharge arc, and the consumable electrode starts to melt. Among them, the melting current is 1.3 - 1.7 kA, and the arc distance of the arc is 10 - 40 mm.

[0055] During the melting stage, control the melting current and time. After the molten pool covers the bottom of the crucible, conduct normal melting until the predetermined weight is reached, specifically as follows: control the melting current to gradually rise to 10 - 15 kA. After the molten pool covers the bottom of the crucible, uniformly increase the melting current from 10 - 15 kA to 30 - 35 kA within 1 - 2 minutes.

[0056] When the titanium liquid in the crucible reaches the predetermined weight, quickly lift the electrode, flip the crucible, and inject the titanium liquid into the mold for cooling. The mold can use a graphite barrel-shaped mold, and its specifications can be φ(300 - 500)×(400 - 950) mm.

[0057] S5. Milling and turning the consumable-electrode skull melting casting blank, and then conducting composition detection.

[0058] In this step, during the composition detection process, if the composition of the consumable-electrode skull melting casting blank meets the following internal control requirements: 6.7% - 7.5% Al, 3.4% - 4.3% V, 1.1% - 1.9% Cr, 0.6% - 1.3% Fe, O ≤ 0.20%, H ≤ 0.015%, N ≤ 0.05%, C ≤ 0.08%, then enter S6; otherwise, conduct alloy compensation in the form of adding alloys according to the detection results of the consumable-electrode skull melting casting blank until the composition meets the internal control requirements and then enter S6.

[0059] S6. Saw the consumable-electrode skull melting casting blank into blocks as consumable-electrode skull materials, place them in the left and right boxes of the electron beam cold hearth furnace, seal the electron beam cold hearth furnace, and conduct vacuum pumping and leak detection.

[0060] This step is the charging of the electron beam cold hearth furnace. Vacuum pump the electron beam cold hearth furnace to ≤8×10 -3 Torr. During leak detection, ensure that the leak rate of the electron beam cold hearth furnace is ≤5 Torr·L / S.

[0061] S7. Confirm the graphic positions of each electron gun in the electron beam cold hearth.

[0062] In this step, refer to the graphic positions of each electron gunFigure 2 As shown, the scanning areas of the 1# electron gun, 2# electron gun, 3# electron gun, and 4# electron gun on the melting zone are the 1# electron gun scanning area 1, 2# electron gun scanning area 2, 3# electron gun scanning area 3, and 4# electron gun scanning area 4 respectively; the scanning area of the 5# electron gun on the refining zone is the 5# electron gun scanning area 5; in the casting zone, the scanning areas of the 6# electron gun and 7# electron gun in the mold 9 are the 6# electron gun scanning area 6 and 7# electron gun scanning area 7;

[0063] Before melting and casting, confirm the graphic boundary positions of each electron gun in the electron beam cold hearth; during the confirmation process, if the graphic positions of all electron guns are accurate (i.e., the graphic boundary positions of each electron gun are at the boundary positions of the corresponding electron gun scanning areas shown), then enter S8, otherwise, adjust the electron guns with graphic position errors until the graphic positions of all electron guns are accurate and then enter S8. Figure 2 After the graphic positions of the electron guns are confirmed in S8, increase the power of the 5# electron gun, 4# electron gun, 3# electron gun, 2# electron gun, and 1# electron gun to 120 - 150 kW to heat and melt the skull material in the cold hearth;

[0064] In S9, start the feeding system, push the skull material into the melting zone, and the 1# electron gun, 2# electron gun, 3# electron gun, and 4# electron gun melt the skull material. After the melted titanium liquid flows into the refining zone, the 5# electron gun refines the titanium liquid. The refined titanium liquid overflows into the mold in the crystallization zone. Turn on the 6# electron gun and 7# electron gun to heat the titanium liquid. When the titanium liquid covers the bottom of the mold, cover the graphic positions of the 6# electron gun and 7# electron gun to the entire mold and increase the power to heat the titanium liquid until the titanium liquid fills the mold and then start ingot pulling;

[0065] In this step, start the feeding system. The feed bins on the left and right sides of the electron beam cold hearth should feed at the same time, push the shell material into the melting zone, and at the same time increase the power of the 1# electron gun, 2# electron gun, 3# electron gun, and 4# electron gun to 150 - 240 kW to melt the skull material in the melting zone. After the melted titanium liquid flows into the refining zone, increase the power of the 5# electron gun to 100 - 130 kW to refine the titanium liquid in the refining zone; the refined titanium liquid overflows into the mold in the crystallization zone. Turn on the 6# electron gun and 7# electron gun to heat the titanium liquid, and the power is 240 - 300 kW at this time; when the titanium liquid covers the bottom of the mold, cover the graphic positions of the 6# electron gun and 7# electron gun to the entire mold and increase the power for melting and casting to make the titanium liquid fully and evenly fill the entire mold to ensure the quality of the ingot head.

[0066]

[0067] ​During the melting and casting process, the power of each electron gun is adjusted to ensure that the melting speed of the solidified shell material matches the ingot pulling speed; specifically: the power of 1# electron gun, 2# electron gun, 3# electron gun, and 4# electron gun is 210~300kW, the power of 5# electron gun is 120~150kW, and the power of 6# electron gun and 7# electron gun is 200~250kW.

[0068] During the ingot pulling process, the ingot pulling speed is controlled at 200±50mm / h, and the liquid level in the crystallizer is controlled at 5~10mm from the edge of the crystallizer to ensure the stability and reliability of the ingot quality.

[0069] The specification of the crystallizer in this step can be 1610×210mm.

[0070] During the above process, the control and power adjustment of the electron gun need to be precisely synchronized to ensure the stability and uniformity of the melting, refining and casting processes.

[0071] S10, after the melting and casting is completed, the tail of the ingot is subjected to shrinkage compensation, and after the shrinkage compensation is completed, the ingot is cooled. After cooling, the electron beam cooling furnace is opened to take out the titanium alloy flat ingot from the crystallizer.

[0072] After the melting and casting is completed, the feeding is stopped and the 1# electron gun, 2# electron gun, 3# electron gun and 4# electron gun are turned off at the same time. When there is no titanium liquid flowing at the gate scanned by the 5# electron gun, the 5# electron gun is turned off and the 6# electron gun and the 7# electron gun are used to feed the shrinkage of the flat ingot formed in the crystallizer; after the shrinkage is completed, it is cooled, and after cooling, the electron beam cooling bed furnace is opened to take out the titanium alloy flat ingot from the crystallizer.

[0073] The method for preparing titanium alloy flat ingots by using a vacuum consumable shell furnace and an electron beam cooling hearth furnace in combination with the present invention is further described below with reference to specific examples.

[0074] Example

[0075] The target composition of the titanium alloy slab cast in this embodiment is: Al, 6%; V, 4.0%; Cr, 1.0%; Fe, 1.0%; the balance is Ti and unavoidable impurities;

[0076] Combination Figure 1 , Figure 2 As shown, the method of preparing titanium alloy flat ingots by using a vacuum consumable shell furnace and an electron beam cooling hearth furnace in this embodiment is as follows:

[0077] (1)Confirm the mass fractions of aluminum and vanadium elements in the TC4 return material. The mass fraction of aluminum element is 5.9%, and the mass fraction of vanadium element is 4%. The rest is titanium element. According to the composition of the TC4 return material, in accordance with the batching target values: Al: 6.90 - 7.25%, V: 3.90 - 4.10%, Cr: 1.50 - 1.65%, Fe: 0.90 - 1.10%, batch aluminum beans, ferrochrome alloy and metallic chromium. The addition ratio of the TC4 return material is 80% of the total raw materials.

[0078] (2)Divide the TC4 return material into two parts. 92 - 95% of the TC4 return material is used as a consumable electrode and welded with the auxiliary electrode of the skull furnace. Install the consumable electrode at the skull furnace rod to ensure good contact between the electrode and the crucible. The remaining approximately 5 - 8% of the TC4 block material is placed at the bottom of the skull furnace crucible as an arc starting bottom pad. Aluminum beans, ferrochrome alloy and metallic chromium are used as the bottom laying materials for the skull furnace. The diameter of the consumable electrode is φ316 mm, the crucible specification is φ450×740 mm, and the casting method is static.

[0079] (3)Seal the skull furnace and perform a vacuum treatment until the vacuum degree in the furnace reaches below 1.5 Pa.

[0080] (4)During the arc starting stage, control the melting current to be 1.3 - 1.7 kA and the arc distance to be 10 - 40 mm to form a stable discharge arc, and the consumable electrode starts to melt.

[0081] (5)During the melting stage, control the melting current to gradually rise to about 10 - 15 kA. When the molten pool covers the bottom of the crucible, raise the current from 10 - 15 kA to 30 - 35 kA uniformly within 1 - 2 minutes and melt normally to the predetermined weight.

[0082] (6)After reaching the predetermined weight, quickly lift the electrode, flip the crucible and inject the titanium liquid into the graphite barrel - shaped mold (specification φ(300 - 500)×(400 - 950) mm), and then cool it to obtain the skull furnace ingot blank.

[0083] (7)After milling and turning the skull furnace ingot blank, conduct chemical composition testing on it. Confirm that the mass fraction of aluminum element in the alloy is 6.9%, the mass fraction of vanadium element is 4.0%, the mass fraction of chromium element is 1.4%, the mass fraction of iron element is 0.8%, and the rest is titanium element, meeting the internal control requirements for the chemical composition of the skull furnace ingot (i.e., 6.7% - 7.5% Al, 3.4% - 4.3% V, 1.1% - 1.9% Cr, 0.6% - 1.3% Fe, O≤0.20%, H≤0.015%, N≤0.05%, C≤0.08%).

[0084] (8) Saw the ingot of the skull melting furnace into blocks as the skull material, place them in the left and right boxes of the electron beam cold hearth furnace charge, seal the electron beam cold hearth furnace and evacuate it to 8×10 -3 Torr; then detect the leak rate of the electron beam cold hearth furnace to ensure that the leak rate does not exceed 5 Torr·L / S.

[0085] (9) As Figure 2 shown, the scanning areas of the 1# electron gun, 2# electron gun, 3# electron gun, and 4# electron gun on the melting zone are the 1# electron gun scanning area 1, 2# electron gun scanning area 2, 3# electron gun scanning area 3, and 4# electron gun scanning area 4 respectively; the scanning area of the 5# electron gun on the refining zone is the 5# electron gun scanning area 5; in the casting zone, the scanning areas of the 6# electron gun and 7# electron gun in the mold 9 are the 6# electron gun scanning area 6 and 7# electron gun scanning area 7; before melting and casting, confirm the graphic positions of the 1# electron gun, 2# electron gun, 3# electron gun, 4# electron gun, 5# electron gun, 6# electron gun, and 7# electron gun. If the graphic positions of all electron guns are accurate, go to S8; otherwise, adjust the electron guns with inaccurate graphic positions until the graphic positions of all electron guns are accurate and then enter S8.

[0086] (10) After the graphic positions of the electron guns are confirmed, sequentially increase the hydrogen supply of the electron guns to increase the power of the 5# electron gun, 4# electron gun, 3# electron gun, 2# electron gun, and 1# electron gun to 120 - 150 kW to heat and melt the skull material in the cold hearth 8 of the electron beam cold hearth furnace.

[0087] (11) Start the feeding system. The left and right material boxes should feed at the same time. Push the ingot blocks of the skull melting furnace into the melting zone, and at the same time increase the power of the 1# electron gun, 2# electron gun, 3# electron gun, and 4# electron gun to 240 kW to melt the ingot blocks in the melting zone. After the melted melt flows into the refining zone, increase the power of the 5# electron gun to 100 - 130 kW for refining. After the refined melt overflows into the mold 9 in the crystallization zone, turn on the 6# electron gun and 7# electron gun to gradually heat the titanium liquid. At this time, the power of the 6# electron gun and 7# electron gun is 280 kW; when the titanium liquid covers the entire mold 9, gradually cover the graphics of the 6# and 7# guns over the entire mold 9 and gradually increase the power for melting and casting to make the titanium liquid fully and evenly fill the entire mold 9 to ensure the quality of the ingot head.

[0088] During the casting process, the power of the 1# electron gun, 2# electron gun, 3# electron gun, and 4# electron gun is 210 - 300 kW, the power of the 5# electron gun is 120 - 150 kW, the power of the 6# electron gun and 7# electron gun is 200 - 250 kW, and the specification of the mold 9 is 1610×210 mm; the ingot pulling speed during casting is controlled at 200 ± 50 mm / h; the liquid level height in the mold 9 is controlled at 5 - 10 mm from the edge of the mold 9.

[0089] (13)After the ingot casting is completed, stop feeding, and at the same time, turn off the 1# electron gun, 2# electron gun, 3# electron gun, and 4# electron gun. Turn off the 5# electron gun when there is no titanium liquid flowing at the gate scanned by the 5# electron gun, and use the 6# electron gun and 7# electron gun to perform feeding to compensate for the shrinkage of the flat ingot formed in the mold 9.

[0090] (14)After the feeding to compensate for the shrinkage is completed, cool it for 3 hours, and finally open the electron beam cold hearth furnace to take out the titanium alloy flat ingot from the mold 9.

[0091] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing titanium alloy flat ingots by using a vacuum consumable shell furnace and an electron beam cooling furnace in combination, characterized in that: It includes the following steps: S1. Confirm the composition of the TC4 return material, and proportion the TC4 return material with aluminum beans, ferrochrome alloy, and metallic chromium according to the target composition of the titanium alloy ingot slab; S2. Divide the TC4 return material into two parts. Make one part of the TC4 return material into a consumable electrode and weld it to the auxiliary electrode of the consumable electrode melting furnace. Place the remaining TC4 return material as an arc starting bottom pad at the bottom of the crucible of the consumable electrode melting furnace, and use aluminum beans, ferrochrome alloy, and metallic chromium as the bottom layer materials for the consumable electrode melting furnace; S3. Seal the consumable electrode melting furnace and conduct vacuum pumping; S4. Melt and cast in the consumable electrode melting furnace. Control the melting current and arc distance during the arc starting stage to form a stable discharge arc; control the melting current and time during the melting stage. After the molten pool covers the bottom of the crucible, use a large current to melt to the predetermined weight, and then inject the titanium liquid into the mold and cool it to obtain the ingot slab of the consumable electrode melting furnace; S5. Milling and turning the ingot slab of the consumable electrode melting furnace and then conducting composition detection. If the composition meets the internal control requirements, proceed to S6; S6. Saw the ingot slab of the consumable electrode melting furnace into blocks as the consumable electrode materials, place them in the left and right boxes of the electron beam cold hearth furnace charge, seal the electron beam cold hearth furnace, and conduct vacuum pumping and leak detection; S7. Confirm the graphic positions of each electron gun in the electron beam cold hearth; S8. After the graphic positions of the electron guns are confirmed, increase the power of the No. 5 electron gun, No. 4 electron gun, No. 3 electron gun, No. 2 electron gun, and No. 1 electron gun to 120 - 150 kW, and heat and melt the consumable electrode materials in the cold hearth; S9. Start the feeding system, push the consumable electrode materials into the melting zone. The No. 1 electron gun, No. 2 electron gun, No. 3 electron gun, and No. 4 electron gun melt the consumable electrode materials. After the melted titanium liquid flows into the refining zone, the No. 5 electron gun refines the titanium liquid. The refined titanium liquid overflows into the crystallizer in the crystallization zone. Turn on the No. 6 electron gun and No. 7 electron gun to heat the titanium liquid. When the titanium liquid covers the bottom of the crystallizer, cover the graphic positions of the No. 6 electron gun and No. 7 electron gun over the entire crystallizer and increase the power for melting and casting until the titanium liquid fills the crystallizer and then start ingot pulling; S10. After the melting and casting is completed, perform risering on the tail of the ingot. After risering is completed, conduct cooling. After cooling, open the electron beam cold hearth furnace and take out the titanium alloy ingot slab from the crystallizer.

2. The method for preparing titanium alloy ingots by duplexing a consumable electroslag remelting furnace and an electron beam cold hearth furnace as claimed in claim 1, characterized in that, In the step S1: The target composition of the titanium alloy ingot slab is as follows by mass percentage: Al: 6.90 - 7.25%, V: 3.90 - 4.10%, Cr: 1.50 - 1.65%, Fe: 0.90 - 1.10%, and the balance is Ti and unavoidable impurities; The addition amount of the TC4 return material is 50 - 80%.

3. The method for preparing titanium alloy flat ingots by duplexing a consumable electroslag remelting furnace and an electron beam cold hearth furnace as claimed in claim 1, characterized in that, In the step S2, the weight of the TC4 return material used for the consumable electrode is 92% - 95% of the total amount of the TC4 return material.

4. The method for preparing titanium alloy flat ingots by duplexing a consumable electroslag remelting furnace and an electron beam cold hearth furnace as claimed in claim 1, characterized in that, In the step S3, after vacuum pumping, the vacuum degree in the consumable electrode melting furnace reaches below 1.5 Pa.

5. The method for preparing titanium alloy flat ingots by duplexing a consumable electroslag remelting furnace with consumable electrodes and an electron beam cold hearth furnace as claimed in claim 1, wherein In the step S4: During the arc starting stage, the melting current is 1.3 - 1.7 kA, and the arc distance of the arc is 10 - 40 mm; In the smelting stage, gradually increase the melting current to 10 - 15 kA. After the molten pool covers the bottom of the crucible, uniformly increase the melting current from 10 - 15 kA to 30 - 35 kA within 1 - 2 minutes. The mold used is a graphite barrel-shaped mold.

6. The method for preparing titanium alloy flat ingots by duplexing a consumable electroslag remelting furnace and an electron beam cold hearth furnace as claimed in claim 1, characterized in that, In step S5, during the composition detection, if the composition of the skull furnace ingot meets the following internal control requirements: 6.7% - 7.5% Al, 3.4% - 4.3% V, 1.1% - 1.9% Cr, 0.6% - 1.3% Fe, O ≤ 0.20%, H ≤ 0.015%, N ≤ 0.05%, C ≤ 0.08%, then proceed to S6; otherwise, perform alloy compensation in the form of adding alloys according to the detection results of the skull furnace ingot until the composition meets the internal control requirements and then proceed to S6.

7. The method for preparing titanium alloy flat ingots by duplexing a consumable electroslag remelting furnace and an electron beam cold hearth furnace as claimed in claim 1, characterized in that, In the step S6, evacuate the electron beam cold hearth furnace to ≤ 8×10 -3 Torr, and ensure that the leakage rate of the electron beam cold hearth furnace is ≤ 5 Torr·L / S during leak detection.

8. The method for preparing titanium alloy flat ingots by using a vacuum consumable shell furnace and an electron beam cooling furnace in a dual connection as claimed in claim 1, characterized in that: In step S7, during the graphic position confirmation, if the graphic positions of all electron guns are accurate, then proceed to S8; otherwise, adjust the electron guns with inaccurate graphic positions until the graphic positions of all electron guns are accurate and then proceed to S8.

9. The method for preparing titanium alloy ingots by duplexing a consumable electroslag remelting furnace and an electron beam cold hearth furnace as claimed in claim 1, characterized in that, In step S9: When melting the skull material, the power of the 1# electron gun, 2# electron gun, 3# electron gun, and 4# electron gun is 150 - 240 kW. When refining the titanium liquid, the power of the 5# electron gun is 100 - 130 kW. Before the titanium liquid covers the bottom of the crystallizer, the power of the 6# electron gun and 7# electron gun is 240 - 300 kW. During the melting and casting process, adjust the power of each electron gun to ensure that the melting speed of the skull material matches the ingot pulling speed. During the ingot pulling process, control the ingot pulling speed at 200 ± 50 mm / h and control the liquid level height in the crystallizer at 5 - 10 mm from the edge of the crystallizer.

10. The method for preparing titanium alloy flat ingots by duplexing a consumable electroslag remelting furnace and an electron beam cold hearth furnace as claimed in claim 9, characterized in that, During the melting and casting process, the power of the 1# electron gun, 2# electron gun, 3# electron gun, and 4# electron gun is 210 - 300 kW, the power of the 5# electron gun is 120 - 150 kW, and the power of the 6# electron gun and 7# electron gun is 200 - 250 kW.

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