Method for preparing titanium alloy slab ingot by duplex vacuum consumable skull furnace and electron beam cold bed furnace

Abstract

The invention discloses a method for preparing a titanium alloy slab ingot by duplex of a vacuum consumable skull furnace and an electron beam cold bed furnace, and the titanium alloy slab ingot which is high in stability and can be used for direct rolling is prepared by adopting a large-proportion TC4 return scrap through a duplex process of the vacuum consumable skull furnace and the electron beam cold bed furnace. According to the method, carbon emission and production cost are effectively reduced from the aspects of raw materials and the preparation process, and recycling of titanium resources and short-process preparation of the titanium alloy are facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy slab smelting, and in particular to a method for preparing titanium alloy slab by using a vacuum consumable shell furnace and an electron beam cooling bed furnace in dual connection. Background Art

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

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

[0004] Both vacuum consumable shell furnaces and electron beam cooling hearth furnaces can effectively remove high and low density inclusions to obtain high-purity titanium alloys. Currently, titanium and titanium alloys are often cast by vacuum consumable melting, but the degree of refining, impurity removal and composition homogenization is limited, and 2 to 3 melting and casting are required, which affects the application of titanium products. Although the electron beam cooling hearth furnace has fewer processes and a high yield rate, it can realize the production of titanium alloys of different shapes and specifications, but it is easy to cause element burnout.

[0005] Therefore, it is urgent to study a method for preparing titanium alloy at low cost using TC4 returned materials. Summary of the invention

[0006] In view of the defects existing in the prior art, the purpose of the present invention is to provide a method for preparing titanium alloy slabs by using a vacuum consumable shell furnace and an electron beam cooling hearth furnace in a dual process. A large proportion of TC4 return material is used to prepare titanium alloy slabs with high stability and can be used for direct rolling through a vacuum consumable shell furnace + electron beam cooling hearth furnace dual process. The present invention effectively reduces carbon emissions and production costs from the aspects of raw materials and preparation technology, and helps to achieve the recycling of titanium resources and the short-process preparation of titanium alloys.

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

[0008] 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 a dual connection, comprising the following steps: 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; 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; S3, sealing the shell furnace and performing vacuum treatment; 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; 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; 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; S7, confirming the graphic position of each electron gun in the electron beam cooling bed; 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; 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; 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.

[0009] Preferably, in step S1: The target composition of the 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; The added amount of the TC4 return material is 50-80%.

[0010] Preferably, in step S2, the weight of the TC4 return material used for the consumable electrode is 92% to 95% of the total amount of the TC4 return material.

[0011] Preferably, in the step S3, after the vacuuming, the vacuum degree in the shell solidification furnace reaches below 1.5 Pa.

[0012] Preferably, in step S4: In the arc starting stage, the melting current is 1.3-1.7 kA, and the arc distance is 10-40 mm; In the smelting stage, the melting current is gradually increased to 10-15 kA, and 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; The mold is a graphite barrel-shaped mold.

[0013] 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 performed in the form of adding alloy according to the detection result of the skull furnace ingot, and then enter S6 after the composition meets the internal control requirements.

[0014] Preferably, in step S6, the electron beam cooling furnace is evacuated to a vacuum of ≤8×10 -3 Torr. During leak detection, ensure that the leakage rate of the electron beam cooling furnace is ≤5 Torr·L / S.

[0015] Preferably, in step S7, during the pattern position confirmation process, if the pattern positions of all electron guns are accurate, then proceed to S8; otherwise, adjust the electron guns with pattern position errors until the pattern positions of all electron guns are accurate before proceeding to S8.

[0016] Preferably, in step S9: When the crust material is melted, the power of the 1# electron gun, the 2# electron gun, the 3# electron gun and the 4# electron gun is 150-240 kW; When refining titanium liquid, the power of the 5# electron gun is 100-130kW; Before the titanium liquid covers the bottom of the crystallizer, the power of the 6# electron gun and the 7# electron gun is 240~300kW; 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; During the ingot pulling process, the ingot pulling speed is controlled at 200±50 mm / h, and the liquid level in the crystallizer is controlled at 5-10 mm from the edge of the crystallizer.

[0017] Preferably, 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.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention recycles a large proportion of TC4 return materials, which can not only reduce the production cost of titanium alloy and improve resource utilization efficiency, but also reduce environmental pollution and achieve sustainable development;

[0020] 2. The present invention adopts a vacuum consumable shell furnace + electron beam cooling furnace dual melting and casting process to effectively reduce element burnout, remove high and low density inclusions, and obtain high-purity titanium alloy. At the same time, TC4 return material can be used to melt and cast titanium alloy ingots that can be directly rolled, which helps to reduce carbon emissions and production costs, and realize the recycling of titanium resources and the short-process preparation technology of titanium alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a flow chart of the method for preparing titanium alloy flat ingots by using a vacuum consumable shell furnace and an electron beam cooling hearth furnace in a dual connection;

[0022] Figure 2 The electron gun scanning area distribution diagram in the electron beam cooling furnace of the present invention;

[0023] Among them, 1, 1# electron gun scanning area, 2, 2# electron gun scanning area, 3, 3# electron gun scanning area; 4, 4# electron gun scanning area, 5, 5# electron gun scanning area, 6, 6# electron gun scanning area, 7, 7# electron gun scanning area; 8, cooling bed; 9, crystallizer. DETAILED DESCRIPTION

[0024] 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.

[0025] 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:

[0026] 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; 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.

[0027] 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; 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.

[0028] S3, sealing the shell furnace and performing vacuum treatment; In this step, the vacuum degree in the shell solidification furnace is ensured to be below 1.5 Pa through vacuum treatment.

[0029] 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; This step is the shell furnace casting, including the arc starting stage and the melting stage; In the arc starting stage, the melting current and arc distance are controlled to form a stable discharge arc, and the consumable electrode begins to melt; the melting current is 1.3~1.7 kA, and the arc distance is 10~40mm; During the smelting stage, the melting current and time are controlled, and the molten metal is normally melted to a predetermined weight after the molten pool covers the bottom of the crucible. Specifically, the melting current is gradually increased to 10-15 kA, and 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 min; When the titanium liquid in the crucible reaches the predetermined weight, the electrode is quickly lifted, the crucible is turned over, and the titanium liquid is injected into the mold for cooling; the mold can be a graphite barrel mold with specifications of φ(300~500)×(400~950) mm.

[0030] S5, milling and turning the ingot cast in the shell furnace and then conducting composition testing; In this step, during the composition detection process, if the composition of the ingot cast in the skull furnace 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 performed in the form of adding alloy according to the detection result of the ingot cast in the skull furnace until the composition meets the internal control requirements and then enter S6.

[0031] 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; This step is to place the electron beam cooling furnace in a vacuum state to ≤8×10 -3 Torr. During leak detection, ensure that the leakage rate of the electron beam cooling furnace is ≤5 Torr·L / S.

[0032] S7, confirming the graphic position of each electron gun in the electron beam cooling bed; In this step, the graphic positions of each electron gun refer to Figure 2 As shown, the scanning areas of the 1# electron gun, the 2# electron gun, the 3# electron gun, and the 4# electron gun on the melting zone are the 1# electron gun scanning area 1, the 2# electron gun scanning area 2, the 3# electron gun scanning area 3, and the 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 the 7# electron gun in the crystallizer 9 are the 6# electron gun scanning area 6 and the 7# electron gun scanning area 7; Before melting and casting, the pattern boundary position of each electron gun in the electron beam cooling bed is confirmed; during the confirmation process, if the pattern position of all electron guns is accurate (that is, the pattern boundary position of each electron gun is within Figure 2If the position of the pattern corresponds to the boundary position of the electron gun scanning area, then enter S8; otherwise, adjust the electron gun with the error in the pattern position until the pattern positions of all electron guns are accurate and then enter S8.

[0033] 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;

[0034] 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; In this step, the feeding system is started, and the left and right side material boxes of the electron beam cooling bed should be fed at the same time, and the shell material is pushed into the melting zone. At the same time, the power of the 1# electron gun, the 2# electron gun, the 3# electron gun and the 4# electron gun is increased to 150~240kW to melt the solidified shell material in the melting zone. After the melted titanium liquid flows into the refining zone, the power of the 5# electron gun is increased to 100~130kW to refine the titanium liquid in the refining zone; the refined titanium liquid overflows into the crystallizer in the crystallization zone, and the 6# electron gun and the 7# electron gun are turned on to heat the titanium liquid, and the power is 240~300kW at this time; when the titanium liquid covers the bottom of the crystallizer, the graphic positions of the 6# electron gun and the 7# electron gun cover the entire crystallizer and the power is increased for melting and casting, so that the titanium liquid fully and evenly fills the entire crystallizer to ensure the quality of the ingot head.

[0035] 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.

[0036] 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.

[0037] The specification of the crystallizer in this step can be 1610×210mm.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] Example

[0043] 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;

[0044] 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:

[0045] (1) Confirm the mass fractions of aluminum and vanadium in the TC4 return material. The mass fraction of aluminum is 5.9%, the mass fraction of vanadium is 4%, and the rest is titanium. According to the composition of the TC4 return material, the aluminum beans, ferrochrome alloy and metallic chromium are proportioned according to the target values ​​of Al: 6.90-7.25%, V: 3.90-4.10%, Cr: 1.50-1.65%, Fe: 0.90-1.10%, and the addition ratio of TC4 return material is 80% of the total raw material.

[0046] (2) The TC4 return material is divided into two parts. 92~95% of the TC4 return material is used as a consumable electrode to weld with the auxiliary electrode of the solidification furnace. The consumable electrode is installed at the charge rod of the solidification furnace to ensure good contact between the electrode and the crucible; the remaining 5~8% of the TC4 block material is placed at the bottom of the crucible of the solidification furnace as an arc starting pad, and aluminum beans, ferrochrome alloy and metallic chromium are used as the bottom material of the solidification furnace; the consumable electrode diameter is φ316 mm, the crucible specification is φ450×740 mm, and the casting method is static.

[0047] (3) Seal the crust furnace and evacuate it until the vacuum degree in the furnace reaches below 1.5 Pa.

[0048] (4) In the arc starting stage, the melting current is controlled to 1.3-1.7 kA and the arc distance is controlled to 10-40 mm to form a stable discharge arc and the consumable electrode begins to melt.

[0049] (5) During the smelting stage, the melting current is controlled to gradually increase to about 10-15 kA. When the molten pool covers the bottom of the crucible, the current is uniformly increased from 10-15 kA to 30-35 kA within 1-2 minutes, and the smelting is carried out normally to the predetermined weight.

[0050] (6) After reaching the predetermined weight, the electrode is quickly lifted, and the crucible is turned over to inject the titanium liquid into a graphite barrel-shaped mold (specification φ(300~500)×(400~950) mm), and then cooled to obtain the shell furnace casting.

[0051] (7) After the surface of the ingot cast in the skull furnace was milled and turned, its chemical composition was tested. It was confirmed that the mass fraction of aluminum in the alloy was 6.9%, the mass fraction of vanadium was 4.0%, the mass fraction of chromium was 1.4%, the mass fraction of iron was 0.8%, and the rest was titanium, which met the internal control requirements of the chemical composition of the ingot cast in the skull furnace (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%).

[0052] (8) Cut the ingots in the shell furnace into blocks as shell materials and place them in the left and right boxes of the electron beam cooling bed. Seal the electron beam cooling bed furnace and evacuate it to 8×10 -3 Torr; then the leakage rate of the electron beam cooling furnace is tested to ensure that the leakage rate does not exceed 5 Torr·L / S.

[0053] (9) Figure 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 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 5# electron gun scanning area 5; in the casting zone, the scanning areas of the 6# electron gun and 7# electron gun in the crystallizer 9 are 6# electron gun scanning area 6 and 7# electron gun scanning area 7; before melting and casting, 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 are confirmed. If the graphic positions of all electron guns are accurate, enter S8, otherwise, adjust the electron guns with errors in the graphic positions until the graphic positions of all electron guns are accurate before entering S8.

[0054] (10) After the pattern position of the electron gun is confirmed, the hydrogen supply of the electron gun is increased in sequence so that 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 shell material in the cooling bed 8 of the electron beam cooling bed furnace.

[0055] (11) Start the feeding system. The left and right side material boxes should feed at the same time. Push the ingots from the solidification furnace into the melting zone. 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 ingots in the melting zone. After the 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 crystallizer 9 in the crystallization zone, turn on the 6# electron gun and the 7# electron gun to gradually heat the titanium liquid. At this time, the power of the 6# electron gun and the 7# electron gun is 280 kW. When the titanium liquid fills the entire crystallizer 9, gradually cover the entire crystallizer 9 with the patterns of the 6# and 7# guns while gradually increasing the power for melting and casting, so that the titanium liquid fully and evenly fills the entire crystallizer 9 to ensure the quality of the ingot head.

[0056] (12) During melting and casting, the power of the 1# electron gun, 2# electron gun, 3# electron gun, and 4# electron gun is 210~300kW, the power of the 5# electron gun is 120~150kW, the power of the 6# electron gun and 7# electron gun is 200~250kW, and the specification of the crystallizer 9 is 1610×210mm; the ingot pulling speed during melting and casting is controlled at 200±50mm / h; the liquid level height in the crystallizer 9 is controlled at 5~10mm from the edge of the crystallizer 9.

[0057] (13) After the ingot is melted, the feeding is stopped and the No. 1, No. 2, No. 3 and No. 4 electron guns are turned off at the same time. When there is no titanium liquid flowing at the gate scanned by the No. 5 electron gun, the No. 5 electron gun is turned off and the No. 6 and No. 7 electron guns are used to compensate for the shrinkage of the flat ingot formed in the crystallizer 9.

[0058] (14) After the shrinkage compensation is completed, the ingot is cooled for 3 hours, and finally the electron beam cooling furnace is opened to take out the titanium alloy ingot from the crystallizer 9.

[0059] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in 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: The following steps are involved: 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; 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; S3, sealing the shell furnace and performing vacuum treatment; 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; 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; 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; S7, confirming the graphic position of each electron gun in the electron beam cooling bed; 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; 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 molten 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 for melting and casting, until the titanium liquid fills the crystallizer and starts to pull the ingot; 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.

2. 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 S1: The target composition of the 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; The added amount of the TC4 return material is 50-80%.

3. 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 the step S2, the weight of the TC4 return material used for the consumable electrode is 92% to 95% of the total amount of the TC4 return material.

4. 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 the step S3, after the vacuuming, the vacuum degree in the shell solidification furnace reaches below 1.5 Pa.

5. 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 S4: In the arc starting stage, the melting current is 1.3-1.7 kA, and the arc distance is 10-40 mm; During the smelting stage, the melting current is gradually increased to 10-15 kA, and 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 min; The mold is a graphite barrel-shaped mold.

6. The method for preparing titanium alloy flat ingots by using a vacuum consumable shell furnace and an electron beam cooling hearth furnace in combination as claimed in claim 1, characterized in that: In the step S5, during the composition detection process, if the composition of the ingot cast in the skull furnace 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 performed in the form of adding alloy according to the detection result of the ingot cast in the skull furnace, and then enter S6 after the composition meets the internal control requirements.

7. 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 S6, the electron beam cooling furnace is evacuated to a vacuum of ≤8×10 -3 Torr. During leak detection, ensure that the leakage rate of the electron beam cooling furnace is ≤5 Torr·L / S.

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 the step S7, during the pattern position confirmation process, if the pattern positions of all electron guns are accurate, then enter S8; otherwise, adjust the electron guns with pattern position errors until the pattern positions of all electron guns are accurate and then enter S8.

9. 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 S9: When the crust material is melted, the power of the 1# electron gun, the 2# electron gun, the 3# electron gun and the 4# electron gun is 150-240 kW; When refining titanium liquid, the power of the 5# electron gun is 100-130kW; Before the titanium liquid covers the bottom of the crystallizer, the power of the 6# electron gun and the 7# electron gun is 240~300kW; 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; During the ingot pulling process, the ingot pulling speed is controlled at 200±50 mm / h, and the liquid level in the crystallizer is controlled at 5-10 mm from the edge of the crystallizer.

10. 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 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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