Vacuum self-consuming skull remelting method for titanium alloy cast ingot

Abstract

The invention belongs to the field of titanium alloy smelting, and relates to a titanium alloy cast ingot vacuum consumable skull remelting method, which comprises the following steps of: distributing materials in a water-cooled copper crucible, sealing the furnace, carrying out arcing smelting through a self-made consumable electrode and raw materials in the crucible, continuously overflowing titanium liquid to fill the bottom of the water-cooled copper crucible, gradually completing smelting and casting into an ingot, through an on-line feeding system, single-furnace multi-time casting is achieved, and casting of 1-5 cast ingots is completed; and breaking the vacuum of the furnace chamber and the casting chamber, lifting out the mold, taking out of the furnace and ingot casting, taking out the skull in the water-cooled copper crucible for local flattening treatment, and paving the skull at the bottom of the water-cooled copper crucible to be used as the skull. According to the method, different raw material forms are combined on the basis of titanium alloy mark components, and equipment and process limitations during remelting of the titanium alloy returned furnace charge are broken through in a process mode of combining presetting in a crucible with online charging, so that high-quality remelting of 20-80% of the returned furnace charge is realized.

Description

Technical Field

[0001] The invention belongs to the field of titanium alloy smelting and relates to a titanium alloy ingot vacuum consumable shell remelting method. Background Art

[0002] As an important equipment for casting manufacturing, vacuum consumable shell furnace has been widely used in static casting or centrifugal casting production of titanium alloy castings. Typical equipment is shown in the large-tonnage new vacuum consumable shell furnace in patent CN 216432469U. Its principle is to apply a sufficiently high voltage between the titanium alloy consumable electrode and the water-cooled crucible in a vacuum or inert atmosphere to cause arc discharge. The high temperature generated by the arc melts the lower end surface of the consumable electrode, and the molten metal drips into the crucible, forming a layer of incompletely melted solidified metal shell (i.e., shell) on the inner wall of the crucible. After the smelting is completed, the molten metal in the crucible is poured into the mold through a rapid flipping device to complete the casting molding, as shown in Type 1 in Table 1.

[0003] With the vigorous development of the titanium industry, the recycling of a large amount of titanium alloy return materials has become a bottleneck restricting the high-quality and sustainable development of the industry. Existing titanium alloy remelting equipment such as vacuum consumable arc furnaces and electron beam / plasma beam cold hearth furnaces have limitations for the remelting of titanium alloy return materials. In response to the remelting of titanium alloy return materials, a new type of vacuum consumable shell furnace has been developed abroad, which combines the melting uniformity of vacuum consumable arc furnaces and the characteristics of cold hearth furnace shell adsorption inclusions. It can efficiently remelt titanium alloy return materials and cast high-quality titanium alloy ingots, such as type 2 in Table 1.

[0004] Table 1. Current situation of titanium alloy melting and casting in vacuum consumable shell furnace

[0005] equipment use Consumable electrode form Crucible form Crucible pre-loaded with raw materials Online feeding Type 1 casting Remelting Ingots / Bars Circular cross section none none Type 2 Ingot Condensation Special cross section New material, return charge none

[0006] Type 2 smelting method uses the solidified shell as the consumable electrode for the next furnace. The solidified shell has absorbed high-density inclusion particles and is reused as a consumable electrode. There is still a risk of inclusions being brought into the ingot. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for remelting titanium alloy ingots by vacuum consumable shell. The present invention is based on the titanium alloy grade composition, combines different raw material forms, and combines the process of pre-setting in the crucible with online feeding to break through the equipment and process limitations of titanium alloy return furnace charge remelting, and achieve high-quality remelting of 20% to 80% return furnace charge.

[0008] In order to achieve the above technical objectives, the technical solution adopted by the embodiment of the present invention is:

[0009] A titanium alloy ingot vacuum consumable shell remelting method comprises the following steps:

[0010] Step S1, open the furnace chamber and place materials in a water-cooled copper crucible;

[0011] Step S2, assembling the titanium alloy consumable electrode onto the electrode rod clamp;

[0012] Step S3, close the furnace chamber and evacuate the vacuum to a vacuum degree of ≤3Pa, perform a leak test to find that the leak rate is ≤1Pa / min, and prepare for smelting after passing the test;

[0013] Step S4, lowering the electrode rod, starting the power supply, and automatically melting after arcing between the consumable electrode and the raw material in the water-cooled copper crucible;

[0014] Step S5, during the smelting process, the titanium liquid fills the bottom of the water-cooled copper crucible, and as the smelting proceeds, the liquid level gradually rises;

[0015] Step S6: After the consumable electrode is smelted, the turning mechanism is started within 3 to 10 seconds to pour the titanium liquid from one side of the water-cooled copper crucible into the mold in the casting chamber, and the remaining titanium liquid is cooled into a solidified shell in the water-cooled copper crucible;

[0016] Step S7, the titanium liquid is cooled and crystallized into an ingot in the mold;

[0017] Step S8, rotating the mold turntable of the casting chamber to another empty mold station;

[0018] Step S9, adding materials online into a water-cooled copper crucible;

[0019] Step S10, repeating steps S4 to S8 for 1 to 5 times to complete the casting of 1 to 5 ingots;

[0020] Step S11, breaking the vacuum of the furnace chamber and the casting chamber, lifting out the mold and taking out the ingot, and at the same time taking out the condensed shell in the water-cooled copper crucible, flattening it locally, and still laying it on the bottom of the water-cooled copper crucible for use as the condensed shell;

[0021] Step S12, repeating steps S1 to S11 for the next round of smelting.

[0022] Furthermore, the raw material in step S1 is one or more combinations of new material of the same grade, returned material in the form of chips and returned material in the form of blocks.

[0023] Furthermore, the titanium alloy consumable electrode in step S2 is selected from the following: a consumable electrode prepared from new materials of the same grade, a consumable electrode prepared from “new materials + returned materials in the form of chips”, a consumable electrode prepared from “new materials + returned materials in the form of small pieces”, a consumable electrode prepared from “new materials + returned materials in the form of chips + returned materials in the form of small pieces”, a remelted titanium alloy ingot (using VAR, EB, etc. to remelt an ingot once), and a consumable electrode welded from a large piece of returned materials;

[0024] Small lump return charge refers to lump return charge with three-dimensional dimensions not exceeding 100mm; large lump return charge refers to lump return charge other than small lump return charge.

[0025] Furthermore, the raw material added in step S9 is a combination of one or more of new material of the same grade, returned material in the form of chips and returned material in the form of small blocks.

[0026] The technical solution provided by the embodiment of the present invention has the following beneficial effects:

[0027] (1) The titanium alloy is kept in a liquid state in a water-cooled copper crucible for 1 to 3 hours. Possible inclusions in the alloy are adsorbed by the condensed shell at the bottom of the crucible through gravity separation, effectively purifying the metal.

[0028] (2) A self-made titanium alloy consumable electrode is used instead of the solidified shell as the consumable electrode to avoid the inclusions adsorbed in the solidified shell from being brought into the ingot for the second time.

[0029] (3) The present invention realizes the casting of 1 to 5 ingots in a single furnace without breaking the vacuum condition by means of online feeding.

[0030] (4) The present invention is based on the composition of titanium alloy grades, combines different raw material forms, and uses a process method that combines pre-loading in the crucible with online feeding to break through the equipment and process limitations when remelting titanium alloy return charges, thereby achieving high-quality remelting of 20% to 80% of the return charge. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] Example 1

[0033] A TC4 titanium alloy ingot vacuum consumable shell remelting method comprises the following steps:

[0034] Step S1, opening the furnace chamber, placing 2.5 tons of TC4 titanium alloy solidified shell in a rectangular cross-section water-cooled copper crucible with an aspect ratio of 2:1, and adding raw material cloth, a total of 1 ton of raw materials are added, wherein, by mass percentage, 30% of the raw materials are TC4 titanium alloy chips-shaped return charge, and 70% are TC4 titanium alloy block-shaped return charge;

[0035] Step S2, assembling a titanium alloy consumable electrode onto an electrode rod clamp, the titanium alloy consumable electrode weighing 4.5 tons, and the consumable electrode is prepared by mixing new materials of the same grade (sponge titanium and vanadium aluminum, aluminum bean master alloy);

[0036] Step S3, close the furnace chamber and evacuate the chamber to a vacuum degree of 1.0 Pa and a gas leakage rate of 0.8 Pa / min. After the chamber passes the test, prepare for smelting.

[0037] Step S4, lowering the electrode rod, starting the power supply, and automatically melting after arcing between the consumable electrode and the raw material in the water-cooled copper crucible;

[0038] Step S5, during the smelting process, the titanium liquid fills the bottom of the water-cooled copper crucible, and as the smelting proceeds, the liquid level gradually rises;

[0039] Step S6, after the consumable electrode is smelted to 1.5 tons, the smelting is stopped, and the turning mechanism is started within 3 to 5 seconds to pour the titanium liquid from one side of the water-cooled copper crucible into the mold in the casting chamber, and the remaining titanium liquid is cooled into a solidified shell in the water-cooled copper crucible;

[0040] Step S7, the titanium liquid is cooled and crystallized into an ingot in the mold;

[0041] Step S8, rotating the mold turntable of the casting chamber to another empty mold station;

[0042] Step S9, adding materials online into a water-cooled copper crucible, adding 1 ton of materials each time, of which, by mass percentage, 30% is TC4 titanium alloy chips-shaped return materials; 70% is TC4 titanium alloy small block return materials, and small block return materials refer to block return materials with a three-dimensional size not exceeding 100 mm;

[0043] Step S10, repeating steps 4 to 8 three times to complete the casting of three 2.5-ton ingots;

[0044] Step S11, breaking the vacuum of the furnace chamber and the casting chamber, lifting out the mold and taking out the ingot, and at the same time taking out the condensed shell in the water-cooled copper crucible, flattening it locally, and still laying it on the bottom of the water-cooled copper crucible for use as the condensed shell;

[0045] Step S12, repeat steps S1 to S11 to carry out the next round of smelting.

[0046] Example 2

[0047] A TB6 titanium alloy ingot vacuum consumable shell remelting method comprises the following steps:

[0048] Step S1, open the furnace chamber, place 2 tons of TB6 titanium alloy solidified shell in a rectangular cross-section water-cooled copper crucible with a length-to-width ratio of 2:1, and add raw material cloth, a total of 1.5 tons of raw materials are added, of which 70% by mass are new materials (sponge titanium and vanadium aluminum iron, vanadium aluminum, aluminum bean master alloy), and 30% are TB6 titanium alloy chips returned to the furnace;

[0049] Step S2, assembling a titanium alloy consumable electrode onto an electrode rod clamp, the titanium alloy consumable electrode weighing 3 tons, and the titanium alloy consumable electrode adopts TB6 titanium alloy large block return charge welded consumable electrode, and the large block return charge refers to block return charge with a three-dimensional size greater than 100 mm;

[0050] Step S3, close the furnace chamber and evacuate the chamber to a vacuum degree of 0.8 Pa and a gas leakage rate of 0.6 Pa / min. After the chamber passes the test, prepare for smelting.

[0051] Step S4, lowering the electrode rod, starting the power supply, and automatically melting after arcing between the consumable electrode and the raw material in the water-cooled copper crucible;

[0052] Step S5, during the smelting process, the titanium liquid fills the bottom of the water-cooled copper crucible, and as the smelting proceeds, the liquid level gradually rises;

[0053] Step S6, after the consumable electrode is smelted to 1.5 tons, the smelting is stopped, and the turning mechanism is started within 5 to 7 seconds to pour the titanium liquid from one side of the water-cooled copper crucible into the mold in the casting chamber, and the remaining titanium liquid is cooled into a solidified shell in the water-cooled copper crucible;

[0054] Step S7, the titanium liquid is cooled and crystallized into an ingot in the mold;

[0055] Step S8, rotating the mold turntable of the casting chamber to another empty mold station;

[0056] Step S9, adding materials online into a water-cooled copper crucible, adding 1.5 tons of materials each time, of which 70% by mass is new material (sponge titanium and vanadium aluminum iron, vanadium aluminum, aluminum bean master alloy), and 30% is TB6 titanium alloy chips returned to the furnace;

[0057] Step S10, repeating steps S4 to S8 twice to complete the casting of two 3-ton ingots;

[0058] Step S11, breaking the vacuum of the furnace chamber and the casting chamber, lifting out the mold and taking out the ingot, and at the same time taking out the condensed shell in the water-cooled copper crucible, flattening it locally, and still laying it on the bottom of the water-cooled copper crucible for use as the condensed shell;

[0059] Step S12, repeat steps S1 to S11 to carry out the next round of smelting.

[0060] Example 3

[0061] A TA15 titanium alloy ingot vacuum consumable shell remelting method, the steps are as follows:

[0062] Step S1, open the furnace chamber, place 2.5 tons of TA15 titanium alloy solidified shell in a rectangular cross-section water-cooled copper crucible with a length-to-width ratio of 2:1, and add raw material cloth, a total of 1 ton of raw material is added, and the raw materials are all TA15 titanium alloy block return charge;

[0063] Step S2, assembling a titanium alloy consumable electrode onto an electrode rod clamp, wherein the weight of the titanium alloy consumable electrode is 8 tons, of which 75% is new material (sponge titanium and molybdenum aluminum, vanadium aluminum, sponge zirconium, aluminum bean master alloy), and 25% is TA15 titanium alloy chips returned to the furnace, and the consumable electrode is prepared after mixing;

[0064] Step S3, close the furnace chamber and evacuate the chamber to a vacuum degree of 0.5 Pa and a gas leakage rate of 0.3 Pa / min. After the chamber passes the test, prepare for smelting.

[0065] Step S4, lowering the electrode rod, starting the power supply, and automatically melting after arcing between the consumable electrode and the raw material in the water-cooled copper crucible;

[0066] Step S5, during the smelting process, the titanium liquid fills the bottom of the water-cooled copper crucible, and as the smelting proceeds, the liquid level gradually rises;

[0067] Step S6, after the consumable electrode is smelted to 1.5 tons, the smelting is stopped, and the turning mechanism is started within 7 to 10 seconds to pour the titanium liquid from one side of the water-cooled copper crucible into the mold in the casting chamber, and the remaining titanium liquid is cooled into a solidified shell in the water-cooled copper crucible;

[0068] Step S7, the titanium liquid is cooled and crystallized into an ingot in the mold;

[0069] Step S8, rotating the mold turntable of the casting chamber to another empty mold station;

[0070] Step S9, adding materials online into a water-cooled copper crucible, adding 1 ton of materials each time, the raw materials are all TA15 titanium alloy small block return materials, and the small block return materials refer to block return materials with a three-dimensional size not exceeding 100 mm;

[0071] Step S10, repeating steps S4 to S8 for 5 times to complete the casting of 5 2.5-ton ingots;

[0072] Step S11, breaking the vacuum of the furnace chamber and the casting chamber, lifting out the mold and taking out the ingot, and at the same time taking out the condensed shell in the water-cooled copper crucible, flattening it locally, and still laying it on the bottom of the water-cooled copper crucible for use as the condensed shell;

[0073] Step S12, repeat steps S1 to S11 to carry out the next round of smelting.

[0074] Example 4

[0075] A TC11 titanium alloy ingot vacuum consumable shell remelting method, the steps are as follows:

[0076] Step S1, open the furnace chamber, place 2.5 tons of TC11 titanium alloy solidified shell in a rectangular cross-section water-cooled copper crucible with an aspect ratio of 2:1, and add raw material cloth, a total of 1 ton of raw materials are added, of which, by mass percentage, 40% are new materials (sponge titanium and molybdenum aluminum, aluminum silicon, sponge zirconium and aluminum beans), 10% are TC11 titanium alloy chips returned to the furnace, and 50% are TC11 titanium alloy block returned to the furnace;

[0077] Step S2, assembling a titanium alloy consumable electrode onto an electrode rod clamp, wherein the titanium alloy consumable electrode weighs 2 tons and is a TC11 titanium alloy VAR remelted primary ingot;

[0078] Step S3, close the furnace chamber and evacuate the chamber to a vacuum degree of 0.7 Pa and a gas leakage rate of 0.4 Pa / min. After the chamber passes the test, prepare for smelting.

[0079] Step S4, lowering the electrode rod, starting the power supply, and automatically melting after arcing between the consumable electrode and the raw material in the water-cooled copper crucible;

[0080] Step S5, during the smelting process, the titanium liquid fills the bottom of the water-cooled copper crucible, and as the smelting proceeds, the liquid level gradually rises;

[0081] Step S6: After the consumable electrode is smelted, the turning mechanism is started within 4 to 8 seconds to pour the titanium liquid from one side of the water-cooled copper crucible into the mold in the casting chamber, and the remaining titanium liquid is cooled into a solidified shell in the water-cooled copper crucible;

[0082] Step S7, the titanium liquid is cooled and crystallized in the mold to form an ingot, and a 3-ton ingot is completed;

[0083] Step S8, breaking the vacuum of the furnace chamber and the casting chamber, lifting out the mold and taking out the ingot from the furnace, and at the same time taking out the condensed shell in the water-cooled copper crucible, flattening it locally, and still laying it on the bottom of the water-cooled copper crucible for use as the condensed shell;

[0084] Step S9, repeat steps S1 to S8 to carry out the next round of smelting.

[0085] Comparative Example

[0086] A TB6 titanium alloy ingot vacuum consumable shell remelting method comprises the following steps:

[0087] Step S1, open the furnace chamber, place 2 tons of TB6 titanium alloy solidified shell in a rectangular cross-section water-cooled copper crucible with a length-to-width ratio of 2:1, and add raw material cloth, a total of 1.5 tons of raw materials are added, of which 70% by mass are new materials (sponge titanium and vanadium aluminum iron, vanadium aluminum, aluminum bean master alloy), and 30% are TB6 titanium alloy chips returned to the furnace;

[0088] Step S2, assembling a titanium alloy consumable electrode onto an electrode rod clamp, the titanium alloy consumable electrode weighing 3 tons, and the consumable electrode is prepared by mixing new materials (sponge titanium and vanadium aluminum iron, vanadium aluminum, aluminum bean master alloy);

[0089] Step S3, close the furnace chamber and evacuate the chamber to a vacuum degree of 0.8 Pa and a gas leakage rate of 0.6 Pa / min. After the chamber passes the test, prepare for smelting.

[0090] Step S4, lowering the electrode rod, starting the power supply, and automatically melting after arcing between the consumable electrode and the raw material in the water-cooled copper crucible;

[0091] Step S5, during the smelting process, the titanium liquid fills the bottom of the water-cooled copper crucible, and as the smelting proceeds, the liquid level gradually rises;

[0092] Step S6, after the consumable electrode is smelted to 1.5 tons, the smelting is stopped, and the turning mechanism is started within 5 to 7 seconds to pour the titanium liquid from one side of the water-cooled copper crucible into the mold in the casting chamber, and the remaining titanium liquid is cooled into a solidified shell in the water-cooled copper crucible;

[0093] Step S7, the titanium liquid is cooled and crystallized into an ingot in the mold;

[0094] Step S8, rotating the mold turntable of the casting chamber to another empty mold station;

[0095] Step S9, adding materials online into a water-cooled copper crucible, adding 1.5 tons of materials each time, of which 70% by mass is new material (sponge titanium and vanadium aluminum iron, vanadium aluminum, aluminum bean master alloy), and 30% is TB6 titanium alloy chips returned to the furnace;

[0096] Step S10, repeating steps S4 to S8 twice to complete the casting of two 3-ton ingots;

[0097] Step S11, breaking the vacuum of the furnace chamber and the casting chamber, lifting out the mold and taking out the ingot, and at the same time taking out the condensed shell in the water-cooled copper crucible, flattening it locally, and still laying it on the bottom of the water-cooled copper crucible for use as the condensed shell;

[0098] Step S12, repeating steps S1 to S11 for the next round of smelting.

[0099] Compared with the comparative example, in Example 2, the consumable electrode is changed from the electrode prepared from new materials to the consumable electrode welded from large blocks of returned furnace materials. The chemical compositions of the ingots smelted by the two methods are shown in Table 2. It can be seen from Table 2 that the uniformity of the chemical composition of the ingots in Example 2 is equivalent to that in the comparative example, and both meet the standard requirements.

[0100] Table 2 Chemical composition of TB6 titanium alloy ingot in Example 2 and Comparative Example

[0101]

[0102] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A titanium alloy ingot vacuum consumable shell remelting method, characterized in that: The following steps are involved: Step S1, open the furnace chamber and place materials in a water-cooled copper crucible; Step S2, assembling the titanium alloy consumable electrode onto the electrode rod clamp; Step S3, close the furnace chamber and evacuate the vacuum to a vacuum degree of ≤3Pa, perform a leak test to find that the leak rate is ≤1Pa / min, and prepare for smelting after passing the test; Step S4, lowering the electrode rod, starting the power supply, and automatically melting after arcing between the consumable electrode and the raw material in the water-cooled copper crucible; Step S5, during the smelting process, the titanium liquid fills the bottom of the water-cooled copper crucible, and as the smelting proceeds, the liquid level gradually rises; Step S6: After the consumable electrode is smelted, the turning mechanism is started within 3 to 10 seconds to pour the titanium liquid from one side of the water-cooled copper crucible into the mold in the casting chamber, and the remaining titanium liquid is cooled into a solidified shell in the water-cooled copper crucible; Step S7, the titanium liquid is cooled and crystallized into an ingot in the mold; Step S8, rotating the mold turntable of the casting chamber to another empty mold station; Step S9, adding materials online into a water-cooled copper crucible; Step S10, repeating steps S4 to S8 for 1 to 5 times to complete the casting of 1 to 5 ingots; Step S11, breaking the vacuum of the furnace chamber and the casting chamber, lifting out the mold and taking out the ingot, and at the same time taking out the condensed shell in the water-cooled copper crucible, flattening it locally, and still laying it on the bottom of the water-cooled copper crucible for use as the condensed shell; Step S12, repeating steps S1 to S11 for the next round of smelting.

2. The titanium alloy ingot vacuum consumable shell remelting method according to claim 1, characterized in that: The raw materials in step S1 are one or more combinations of new materials of the same grade, returned materials in the form of chips and returned materials in the form of blocks.

3. The titanium alloy ingot vacuum consumable shell remelting method according to claim 1, characterized in that: The titanium alloy consumable electrode in step S2 is selected from the group consisting of a consumable electrode prepared from new material of the same grade, a consumable electrode prepared from "new material + returned charge in the form of chips", a consumable electrode prepared from "new material + returned charge in the form of small pieces", a consumable electrode prepared from "new material + returned charge in the form of chips + returned charge in the form of small pieces", and a consumable electrode welded from a remelted titanium alloy ingot and a returned charge in the form of large pieces; Small lump return charge refers to lump return charge with three-dimensional dimensions not exceeding 100 mm; large lump return charge refers to lump return charge other than small lump return charge.

4. The titanium alloy ingot vacuum consumable shell remelting method according to claim 1, characterized in that: The raw materials added in step S9 are one or more combinations of new materials of the same grade, returned materials in the form of chips, and returned materials in the form of small blocks.

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