A method for controlling the composition uniformity of TC32 titanium alloy ingot

Abstract

The present application relates to titanium alloy processing technology field, disclose a kind of TC32 titanium alloy ingot component uniformity control method, comprising the following steps: step one, making integral electrode, raw material is mixed uniformly, then the mixed raw material is pressed into integral electrode in integral electrode press, raw material includes titanium sponge, aluminium bean, Al-Mo intermediate alloy, Al-Cr intermediate alloy, zirconium sponge, Ti-Si intermediate alloy, TiO2 Powder;Step two, three vacuum consumable melting, the integral electrode in step one is installed to smelting crucible crystallizer, carries out first vacuum consumable melting and obtains primary ingot, the second vacuum consumable melting is carried out to primary ingot and obtains secondary ingot, then the third vacuum consumable melting is carried out to secondary ingot and obtains cast ingot.The present application patent solves the problem of poor component uniformity in the preparation process of TC32 titanium alloy ingot in the prior art.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy processing technology, specifically to a method for controlling the compositional uniformity of TC32 titanium alloy ingots. Background Technology

[0002] TC32 titanium alloy, with a nominal chemical composition of Ti-5Al-3Mo-3Cr-1Zr-0.1Si, is a medium-to-high strength, high-toughness α+β type two-phase titanium alloy. It features high specific strength, high impact resistance, and high fracture toughness, and is widely used in structural components, fasteners, and aero-engine parts for fighter jets, transport aircraft, and trainer aircraft. Excellent ingot compositional uniformity and purity are fundamental guarantees for improving the damage tolerance performance of aircraft structural components. TC32 titanium alloy has a high degree of alloying and a wide variety of alloying elements, requiring the electrode preparation and vacuum self-consumption processes to comprehensively consider the characteristics of each component.

[0003] Currently, the general process for producing TC32 titanium alloy ingots involves first fabricating an integral electrode, then installing it into a melting crucible crystallizer. The integral electrode and the melting crucible crystallizer are connected to the negative and positive terminals of a power supply, respectively. Under vacuum, a melting current and voltage are applied, causing the integral electrode to continuously melt into metal droplets that fall into the crucible, eventually cooling to form the titanium alloy ingot. However, in existing processes, due to the diverse alloying elements in TC32 titanium alloy, poor ingot compositional uniformity is easily encountered during melting, particularly severe segregation of elements such as Al, which affects ingot quality. Summary of the Invention

[0004] The present invention aims to provide a method for controlling the compositional uniformity of TC32 titanium alloy ingots, so as to solve the problem of poor compositional uniformity in the preparation process of TC32 titanium alloy ingots in the prior art.

[0005] During the preparation of TC32 ingots, the inventors discovered a significant problem with the Al element in the ingots. On the one hand, there was a substantial loss of Al element after preparation; on the other hand, the loss of Al element was more severe closer to the riser. After in-depth analysis, the inventors believe that the reason for the aforementioned problem is that, due to Al's low melting point and high saturated vapor pressure, aluminum briquettes are currently used directly as raw materials in smelting. However, the temperature during the smelting of consumable electrodes is very high. For example, the melting point of sponge titanium is about 1670℃, while the melting point of aluminum briquettes is about 660℃. Therefore, aluminum briquettes are prone to volatilization during smelting, causing localized loss of Al element, especially severe loss of Al element closer to the riser. Adding more aluminum briquettes to the raw materials to compensate for the loss of Al through volatilization at the riser location can lead to higher Al content in other parts, even exceeding the upper limit of the standard requirements. In addition, during the smelting process, gaseous elements such as O, N, and H are easily introduced into the ingot during the ingot production process, causing localized deterioration of the product's properties. Localized enrichment may produce low-density inclusions, which seriously affect the quality of ingot preparation. Therefore, it is necessary to further improve the existing TC32 ingot preparation method to reduce Al volatilization and component segregation during the ingot production process and improve the uniformity of ingot composition.

[0006] To solve the above problems, the present invention adopts the following technical solution: a method for controlling the compositional uniformity of TC32 titanium alloy ingots, comprising the following steps: Step 1: Fabricate the integral electrode. Prepare and mix the raw materials evenly, and then press the evenly mixed raw materials into an integral electrode in an integral electrode press. The raw materials include sponge titanium, aluminum granules, Al-Mo master alloy, Al-Cr master alloy, sponge zirconium, Ti-Si master alloy, and TiO2 powder. Step 2: Three-stage vacuum consumable melting. The integral electrode from Step 1 is installed into the melting crucible crystallizer, and the first vacuum consumable melting is performed to obtain a primary ingot. The primary ingot is then subjected to a second vacuum consumable melting to obtain a secondary ingot. Finally, the secondary ingot is subjected to a third vacuum consumable melting to obtain a cast ingot.

[0007] The principles and beneficial effects of this scheme are as follows: In this application, when setting raw materials in step one during the fabrication of the integral electrode, in addition to conventional raw materials such as sponge titanium, aluminum briquettes, sponge zirconium, and TiO2 powder, Al-Mo master alloy, Al-Cr master alloy, and Ti-Si master alloy are also set. On the one hand, Al-Mo master alloy and Al-Cr master alloy are used as sources of Mo and Cr elements in TC32, and Al elements are supplemented by Al elements. With aluminum briquettes already set, Al elements are effectively supplemented. More importantly, the melting point of sponge titanium during the smelting process is about 1670℃. For example, the melting point of Al-60Mo master alloy is 1570℃, and the melting point of Al-Cr master alloy is also slightly lower than that of sponge titanium. Therefore, during the smelting process, as sponge titanium melts, each master alloy can also slowly follow suit. Compared with directly using aluminum briquettes to provide Al elements, it can effectively reduce the waste caused by Al element volatilization. Moreover, by adopting the method of this application, the amount of Al elements in the ingot can be more stably guaranteed, and the uniformity of the ingot composition can be improved.

[0008] Meanwhile, in step two of this application, a three-stage vacuum self-consumption melting method is adopted. Through multiple melting processes, gaseous elements such as O, N, and H, as well as volatile impurity elements (such as sulfur) in the titanium alloy can be removed more thoroughly, high-density inclusions are removed, and the structural organization is optimized, making it particularly suitable for large-scale industrial production needs.

[0009] Preferably, as an improvement, the Al-Mo master alloy is an Al-60Mo master alloy, the Al-Cr master alloy is an Al-70Cr master alloy, and the Ti-Si master alloy is a Ti-50Si master alloy, wherein the particle size of the sponge titanium is 10-50.0 mm, the particle size of the aluminum granules is 20.0-30.0 mm, and the particle size of the Al-70Cr master alloy is 10.0-20.0 mm.

[0010] Preferably, as an improvement, the weight percentages of each raw material in step one are as follows: Al-60Mo master alloy 4.40–5.20%, sponge zirconium 0.80–1.30%, aluminum briquettes 2.00–2.80%, Al-70Cr master alloy 3.50–4.30%, Ti-50Si master alloy 0.15–0.25%, TiO2 0.05–0.15%, and sponge titanium 85–89%.

[0011] Preferably, as an improvement, in step two, during the first vacuum self-consumption melting, the vacuum degree is less than or equal to 5.0 Pa, the melting current is 25-36 kA, and the melting voltage is 28-40 V.

[0012] Preferably, as an improvement, in step two, during the second vacuum self-consumption melting process, the vacuum degree is less than or equal to 3.0 Pa, the melting current is 32-42 kA, and the melting voltage is 31-50 V.

[0013] Preferably, as an improvement, during the third vacuum self-consumption melting in step two, the vacuum degree is less than or equal to 3.0 Pa, the melting current is 22-32 kA, and the melting voltage is 26-40 V.

[0014] Preferably, as an improvement, during the third vacuum self-consumable melting in step two, when the remaining weight of the self-consumable electrode is 200-300 kg, the stirring current is increased to compensate for shrinkage. After the compensation begins, the stirring current gradually decreases, and the depth of the molten pool gradually decreases.

[0015] Preferably, as an improvement, in step two, the cooling time after the first vacuum self-consumption melting is greater than or equal to 5 hours, the cooling time after the second vacuum self-consumption melting is greater than or equal to 7 hours, and the cooling time after the third vacuum self-consumption melting is greater than or equal to 7 hours.

[0016] Preferably, as an improvement, the number of integral electrodes fabricated in step one is at least two, and the density of the integral electrodes ranges from 3.4 to 3.8 g / cm³. 3 The length of a single integral electrode is 4.0 to 6.0 m.

[0017] Preferably, as an improvement, in step two, during the first vacuum self-consumable melting, each integral electrode from step one is melted separately, and then before the second vacuum self-consumable melting, all the primary ingots are sequentially welded in the melting crucible crystallizer to form columnar ingots. During the welding process, the vacuum degree is less than or equal to 5.0 Pa, the welding current is 20-30 kA, and the welding voltage is 31-50 V.

[0018] The beneficial effects of this plan are: 1. In this scheme, when setting the master alloys, the Al-Mo master alloy is Al-60Mo master alloy, the Al-Cr master alloy is Al-70Cr master alloy, and the Ti-Si master alloy is Ti-50Si master alloy. Among them, the Al-60Mo master alloy refers to a Mo content of 60%, and the Al-70Cr master alloy has a Cr content of 70%. This not only effectively ensures the content of Mo and Cr elements in the corresponding master alloys, but also makes the preparation of binary alloys simple, the process mature, and the cost low. At the same time, when the content of each metal element in the binary master alloy is controlled within the aforementioned range, the melting point of each binary master alloy can be close to that of sponge titanium, so that the melting of all raw materials can be completed simultaneously and efficiently during smelting, thereby improving the uniformity of the ingot composition.

[0019] 2. In this scheme, Al is introduced through Al-60Mo and Al-70Cr master alloys to reduce the weight proportion of aluminum briquettes and mitigate Al volatilization during smelting. Simultaneously, because a 10,000-ton vertical semi-continuous consumable electrode extrusion press is used to prepare the integral consumable electrode, this equipment has sufficient capacity to handle larger raw material particles, thereby producing a higher density integral electrode. Therefore, this scheme designs many raw materials to be larger in size than commonly used raw materials on the market. The changes in raw material dimensions are as follows:

[0020] This solution increases the particle size of the raw materials, which reduces manufacturing costs and offers the following unique technical benefits: The inventors discovered that, within the limits of equipment capacity, increasing the particle size of sponge titanium improves pressing density, enhances the connection strength of consumable electrodes, reduces electrode welding, improves the stability of the melting process, and increases production efficiency. However, with increased sponge titanium particle size, the large particle size difference between various intermediate alloys and sponge titanium during the raw material mixing stage can easily lead to agglomeration of intermediate alloy powder, resulting in uneven mixing and affecting the overall electrode extrusion weight, ultimately impacting the ingot production quality. Therefore, the particle size of the intermediate alloys is also appropriately increased. Furthermore, larger particle sizes of intermediate alloys facilitate better mechanical bonding and allow for stable and uniform melting into droplets on the electrode during the melting process. In contrast, while smaller particle sizes may seem easier to melt, their uneven distribution and tendency to clump together, coupled with the difficulty in deformation and poor mechanical bonding of hard, small-particle alloys, make them prone to falling directly into the molten pool during melting, hindering thorough melting and mixing. Therefore, using the intermediate alloy with the particle size range in this scheme can not only improve the uniformity of mixing when extruding to prepare integral electrodes, but also ensure stable and uniform melting and dropping during the smelting process, thereby improving the uniformity of ingot composition.

[0021] 3. This application incorporates three vacuum consumable melting processes. In the second vacuum consumable melting process, compared to the other two, the vacuum degree is lower, the melting current is higher, and the melting voltage is higher. This low-high-low melting parameter requirement effectively suppresses Cr segregation and more thoroughly removes gaseous elements such as O, N, and H. Furthermore, during the third vacuum consumable melting process, when the remaining weight of the consumable electrode is 200-300 kg, the stirring current is increased for feeding. This strengthens the stirring current during the feeding stage at the end of the finished product melting process, ensuring thorough agitation of the molten pool and preventing severe Al volatilization and associated Al-rich segregation at the riser. Simultaneously, the stirring current gradually decreases after the feeding begins, gradually reducing the depth of the molten pool during melting, thus accelerating the solidification rate and suppressing the redistribution of solute elements between the solid and liquid phases during solidification, thereby reducing the segregation of various elements at the riser.

[0022] 4. In step one of this application, at least two integral electrodes are fabricated. Furthermore, during the first vacuum arc remelting in step two, all integral electrodes from step one are melted individually to obtain an equal number of primary ingots. These primary ingots are then welded together into a single columnar ingot, which is then moved to a melting crucible crystallizer for a second vacuum arc remelting. This method of welding multiple primary ingots before performing a second vacuum arc remelting effectively compensates for losses during the first vacuum arc remelting process, ensuring that the crucible ratio is within a suitable range during both the second and third vacuum arc remelting processes. Attached Figure Description

[0023] Figure 1 This is a sampling location diagram for Embodiment 1 and Comparative Example 1 of the present invention.

[0024] Figure 2 This is a cross-sectional view of the ingot in Embodiment 1 of the present invention.

[0025] Figure 3 This is a photograph of the ingot prepared in Embodiment 1 of the present invention.

[0026] The following detailed description illustrates the specific implementation method: Example

[0027] This first embodiment describes a method for controlling the compositional uniformity of TC32 titanium alloy ingots, comprising the following steps: Step 1: Fabrication of the monolithic electrode. The raw materials are prepared and mixed evenly. Then, the evenly mixed raw materials are pressed into a monolithic electrode using a monolithic electrode press. The raw materials include sponge titanium, aluminum granules, Al-Mo master alloy, Al-Cr master alloy, sponge zirconium, Ti-Si master alloy, and TiO2 powder. The Al-Mo master alloy is Al-60Mo master alloy, the Al-Cr master alloy is Al-70Cr master alloy, and the Ti-Si master alloy is Ti-50Si master alloy. The particle size of the sponge titanium is 10–50 mm, the aluminum granules are 20–30 mm, and the Al-60Mo master alloy has a particle size range of 1–10 mm. The 70Cr master alloy has a particle size of 10–20 mm. The weight percentages of each raw material are as follows: Al-60Mo master alloy 4.40–5.20%, preferably 4.70%; sponge zirconium 0.80–1.30%, preferably 1.00%; aluminum briquettes 2.00–2.80%, preferably 2.30%; Al-70Cr master alloy 3.50–4.30%, preferably 4.20%; Ti-50Si master alloy 0.15–0.25%, preferably 0.20%; TiO2 0.05–0.15%, preferably 0.10%; and sponge titanium 85–89%, preferably 87.5%. Furthermore, at least two integral electrodes are used in the fabrication process; in this embodiment, two electrodes are preferred. During actual fabrication, the uniformly mixed raw materials are pressed into a single electrode with a weight of 2.5T, a diameter of φ435mm, and a density of 3.6g / cm³. 3 Two integral electrodes, each 4.6m in length.

[0028] Step 2: Three-stage vacuum consumable melting. The integral electrode from Step 1 is installed into the melting crucible crystallizer, and a first vacuum consumable melting is performed to obtain a primary ingot. The primary ingot is then subjected to a second vacuum consumable melting to obtain a secondary ingot. The secondary ingot is then subjected to a third vacuum consumable melting to obtain a cast ingot. After obtaining the cast ingot, the surface is machined to obtain the TC32 titanium alloy finished cast ingot.

[0029] During a single vacuum arc remelting process, the vacuum level is less than or equal to 5.0 Pa, preferably less than or equal to 3.0 Pa. The melting current is 25–36 kA, preferably 27–30 kA, and the melting voltage is 28–40 V, preferably 32–35 V. The diameter of the melting crucible crystallizer during the single vacuum arc remelting is φ560 mm. The two integral electrodes from step one are individually subjected to a single vacuum arc remelting. After melting, the cooling time is greater than or equal to 5 hours, preferably 6 hours. After the two integral electrodes have each completed a single vacuum arc remelting, the two primary ingots are welded in a furnace in a melting crucible crystallizer with a diameter of φ650 mm. The welding vacuum level is less than or equal to 5.0 Pa, preferably less than or equal to 3.0 Pa. The welding current is 20–30 kA, preferably 23–26 kA, and the welding voltage is 31–50 V, preferably 35–45 kA. Finally, a columnar ingot with a columnar structure is formed by welding.

[0030] During the second vacuum arc remelting, the columnar ingot obtained from the first vacuum arc remelting and welding is placed in a φ650mm melting crucible crystallizer for direct second vacuum arc remelting. During the melting process, the vacuum degree is less than or equal to 3.0 Pa, preferably less than or equal to 2.0 Pa, the melting current is 32-42 kA, preferably 36-39 kA, the melting voltage is 26-40 V, preferably 33-37 V, and the cooling time after melting is greater than or equal to 7 h, preferably 8 h.

[0031] During the third vacuum consumable melting process, the secondary ingot is installed in a φ740mm melting crucible crystallizer. The vacuum degree during melting is less than or equal to 3.0 Pa, preferably less than or equal to 1.0 Pa. The melting current is 22–32 kA, preferably 25–29 kA, and the melting voltage is 26–40 V, preferably 32–36 V. Simultaneously, when the remaining weight after the third vacuum consumable melting is 200–300 kg, the stirring current is increased for replenishment. After replenishment begins, the stirring current is gradually decreased, and the depth of the molten pool gradually decreases. The stirring current is set according to the table below during replenishment:

[0032] After obtaining the TC32 titanium alloy finished ingot, chemical composition was tested at 9 points along the transverse direction of the ingot. The sampling and testing points are as follows: Figure 1 As shown, the sampling test results of Example 1 are as follows:

[0033] Comparative Example 1 Includes the following steps: Step 1: Fabricate the integral electrode. Prepare and mix the raw materials evenly, and then press the evenly mixed raw materials into an integral electrode in an integral electrode press. The raw materials include sponge titanium, aluminum granules, Al-Mo master alloy, elemental Cr metal, sponge zirconium, Ti-Si master alloy, and TiO2 powder. The Al-Mo master alloy is Al-60Mo master alloy, the Ti-Si master alloy is Ti-50Si master alloy, and the particle size of sponge titanium is 10-25.4 mm, the particle size of aluminum granules is 10-13 mm, and the particle size range of Al-60Mo master alloy is 1-3 mm. Meanwhile, the weight percentages of each raw material are as follows: Al-60Mo master alloy 4.40–5.20%, preferably 4.70%; sponge zirconium 0.80–1.30%, preferably 1.00%; aluminum briquettes 2.90–3.70%, preferably 3.30%; elemental Cr 2.60–3.40%, preferably 3.00%; Ti-50Si master alloy 0.15–0.25%, preferably 0.20%; TiO2 0.05–0.15%, preferably 0.10%; and sponge titanium 85–89%, preferably 87.5%. Furthermore, when fabricating the integral electrode, the number of integral electrodes is at least two; in this embodiment, two electrodes are preferred. In actual fabrication, the uniformly mixed raw materials are pressed into a single electrode with a weight of 2.5T, a diameter of φ435mm, and a density of 3.6g / cm³. 3 Two integral electrodes, each 4.6m in length.

[0034] Step Two: Three Vacuum Arsenic Melting Processes. The integral electrode from Step One is installed into the melting crucible crystallizer. A first vacuum arsenic melting process is performed to obtain a primary ingot. The primary ingot is then subjected to a second vacuum arsenic melting process to obtain a secondary ingot. The secondary ingot is then subjected to a third vacuum arsenic melting process to obtain a cast ingot. After obtaining the cast ingot, surface machining is performed to obtain the desired result. Figure 3 The TC32 titanium alloy finished ingot shown.

[0035] During a single vacuum arc remelting process, the vacuum level is less than or equal to 5.0 Pa, preferably less than or equal to 3.0 Pa. The melting current is 25–36 kA, preferably 27–30 kA, and the melting voltage is 28–40 V, preferably 32–35 V. The diameter of the melting crucible crystallizer during the single vacuum arc remelting is φ560 mm. The two integral electrodes from step one are individually subjected to a single vacuum arc remelting. After melting, the cooling time is greater than or equal to 5 hours, preferably 6 hours. After the two integral electrodes have each completed a single vacuum arc remelting, the two primary ingots are welded in a furnace in a melting crucible crystallizer with a diameter of φ650 mm. The welding vacuum level is less than or equal to 5.0 Pa, preferably less than or equal to 3.0 Pa. The welding current is 20–30 kA, preferably 23–26 kA, and the welding voltage is 31–50 V, preferably 35–45 kA. Finally, a columnar ingot with a columnar structure is formed by welding.

[0036] During the second vacuum arc remelting, the columnar ingot obtained from the first vacuum arc remelting and welding is placed in a φ650mm melting crucible crystallizer for direct second vacuum arc remelting. During the melting process, the vacuum degree is less than or equal to 3.0 Pa, preferably less than or equal to 2.0 Pa, the melting current is 32-42 kA, preferably 36-39 kA, the melting voltage is 26-40 V, preferably 33-37 V, and the cooling time after melting is greater than or equal to 7 h, preferably 8 h.

[0037] During the third vacuum consumable melting process, the secondary ingot is installed in a φ740mm melting crucible crystallizer. The vacuum degree during melting is less than or equal to 3.0 Pa, preferably less than or equal to 1.0 Pa. The melting current is 22–32 kA, preferably 25–29 kA, and the melting voltage is 26–40 V, preferably 32–36 V. Simultaneously, when the remaining weight after the third vacuum consumable melting is 200–300 kg, the stirring current is increased for replenishment. After replenishment begins, the stirring current is gradually decreased, and the depth of the molten pool gradually decreases. The stirring current is set according to the table below during replenishment:

[0038] After obtaining the TC32 titanium alloy finished ingot, chemical composition was tested at 9 points along the transverse direction of the ingot. The sampling and testing points are as follows: Figure 1 As shown, the sampling test results for Comparative Example 1 are as follows:

[0039] Comparative Example 2 Includes the following steps: Step 1: Fabrication of the monolithic electrode. The raw materials are prepared and mixed evenly. Then, the evenly mixed raw materials are pressed into a monolithic electrode using a monolithic electrode press. The raw materials include sponge titanium, aluminum granules, Al-Mo master alloy, Al-Cr master alloy, sponge zirconium, Ti-Si master alloy, and TiO2 powder. The Al-Mo master alloy is Al-60Mo master alloy, the Al-Cr master alloy is Al-70Cr master alloy, and the Ti-Si master alloy is Ti-50Si master alloy. The particle size of the sponge titanium is 10–50 mm, the aluminum granules are 20–30 mm, and the Al-60Mo master alloy has a particle size range of 1–10 mm. The 70Cr master alloy has a particle size of 10–20 mm. The weight percentages of each raw material are as follows: Al-60Mo master alloy 4.40–5.20%, preferably 4.70%; sponge zirconium 0.80–1.30%, preferably 1.00%; aluminum briquettes 2.00–2.80%, preferably 2.30%; Al-70Cr master alloy 3.50–4.30%, preferably 4.20%; Ti-50Si master alloy 0.15–0.25%, preferably 0.20%; TiO2 0.05–0.15%, preferably 0.10%; and sponge titanium 85–89%, preferably 87.5%. Furthermore, at least two integral electrodes are used in the fabrication process; in this embodiment, two electrodes are preferred. During actual fabrication, the uniformly mixed raw materials are pressed into a single electrode with a weight of 2.5T, a diameter of φ435mm, and a density of 3.6g / cm³. 3 Two integral electrodes, each 4.6m in length.

[0040] Step 2: Three-stage vacuum consumable melting. The integral electrode from Step 1 is installed into the melting crucible crystallizer, and a first vacuum consumable melting is performed to obtain a primary ingot. The primary ingot is then subjected to a second vacuum consumable melting to obtain a secondary ingot. The secondary ingot is then subjected to a third vacuum consumable melting to obtain a cast ingot. After obtaining the cast ingot, the surface is machined to obtain the TC32 titanium alloy finished cast ingot.

[0041] During a single vacuum arc remelting process, the vacuum level is less than or equal to 5.0 Pa, preferably less than or equal to 3.0 Pa. The melting current is 25–36 kA, preferably 27–30 kA, and the melting voltage is 28–40 V, preferably 32–35 V. The diameter of the melting crucible crystallizer during the single vacuum arc remelting is φ560 mm. The two integral electrodes from step one are individually subjected to a single vacuum arc remelting. After melting, the cooling time is greater than or equal to 5 hours, preferably 6 hours. After the two integral electrodes have each completed a single vacuum arc remelting, the two primary ingots are welded in a furnace in a melting crucible crystallizer with a diameter of φ650 mm. The welding vacuum level is less than or equal to 5.0 Pa, preferably less than or equal to 3.0 Pa. The welding current is 20–30 kA, preferably 23–26 kA, and the welding voltage is 31–50 V, preferably 35–45 kA. Finally, a columnar ingot with a columnar structure is formed by welding.

[0042] During the second vacuum arc remelting, the columnar ingot obtained from the first vacuum arc remelting and welding is placed in a φ650mm melting crucible crystallizer for direct second vacuum arc remelting. During the melting process, the vacuum degree is less than or equal to 3.0 Pa, preferably less than or equal to 2.0 Pa, the melting current is 32-42 kA, preferably 36-39 kA, the melting voltage is 26-40 V, preferably 33-37 V, and the cooling time after melting is greater than or equal to 7 h, preferably 8 h.

[0043] During the third vacuum consumable melting process, the secondary ingot is installed in a φ740mm melting crucible crystallizer. The vacuum degree during melting is less than or equal to 3.0 Pa, preferably less than or equal to 1.0 Pa. The melting current is 22–32 kA, preferably 25–29 kA, and the melting voltage is 26–40 V, preferably 32–36 V. Simultaneously, when the remaining weight after the third vacuum consumable melting is 200–300 kg, the stirring current is increased for replenishment. After replenishment begins, the stirring current is gradually decreased, and the depth of the molten pool gradually decreases. The stirring current is set according to the table below during replenishment:

[0044] After obtaining the TC32 titanium alloy finished ingot, chemical composition was tested at 9 points along the transverse direction of the ingot. The sampling and testing points are as follows: Figure 1 As shown, the sampling test results for Comparative Example 2 are as follows:

[0045] The stability analysis of the detection results data of Example 1, Comparative Example 1, and Comparative Example 2 is shown in the table below:

[0046] As can be seen from the statistical data, Example 1 has three significant improvements in component uniformity compared to Comparative Example 1 and Comparative Example 2: 1. The average value of Al element has increased and is close to the design value, indicating that the overall volatilization of Al element has decreased.

[0047] 2. The range of Al element decreased, and the Al element content at position 1 of the riser was close to the design value, indicating that Al volatilization at the riser was significantly improved.

[0048] 3. The uniformity of the main elements other than Al in the experimental example is also better than that in the comparative example.

[0049] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for controlling the compositional uniformity of TC32 titanium alloy ingots, comprising the following steps: Step 1: Fabricate the integral electrode. Prepare and mix the raw materials evenly, and then press the evenly mixed raw materials into an integral electrode in an integral electrode press. The raw materials include sponge titanium, aluminum granules, Al-Mo master alloy, Al-Cr master alloy, sponge zirconium, Ti-Si master alloy, and TiO2 powder. Step 2: Three-stage vacuum consumable melting. The integral electrode from Step 1 is installed into the melting crucible crystallizer, and the first vacuum consumable melting is performed to obtain a primary ingot. The primary ingot is then subjected to a second vacuum consumable melting to obtain a secondary ingot. Finally, the secondary ingot is subjected to a third vacuum consumable melting to obtain a cast ingot.

2. The method for controlling the compositional uniformity of TC32 titanium alloy ingots according to claim 1, characterized in that: The Al-Mo master alloy is Al-60Mo master alloy, the Al-Cr master alloy is Al-70Cr master alloy, and the Ti-Si master alloy is Ti-50Si master alloy, wherein the particle size of the sponge titanium is 10-50 mm, the particle size of the aluminum granules is 20-30 mm, and the particle size of the Al-70Cr master alloy is 10-20 mm.

3. The method for controlling the compositional uniformity of TC32 titanium alloy ingots according to claim 1, characterized in that: The weight percentages of each raw material in step one are as follows: Al-60Mo master alloy 4.40–5.20%, sponge zirconium 0.80–1.30%, aluminum briquettes 2.00–2.80%, Al-70Cr master alloy 3.50–4.30%, Ti-50Si master alloy 0.15–0.25%, TiO2 0.05–0.15%, and sponge titanium 85–89%.

4. The method for controlling the compositional uniformity of TC32 titanium alloy ingots according to claim 1, characterized in that: In step two, during the first vacuum self-consumption melting process, the vacuum degree is less than or equal to 5.0 Pa, the melting current is 25-36 kA, and the melting voltage is 28-40 V.

5. The method for controlling the compositional uniformity of TC32 titanium alloy ingots according to claim 1, characterized in that: In step two, during the second vacuum self-consumption melting process, the vacuum degree is less than or equal to 3.0 Pa, the melting current is 32-42 kA, and the melting voltage is 31-50 V.

6. The method for controlling the compositional uniformity of TC32 titanium alloy ingots according to claim 1, characterized in that: In step two, during the third vacuum self-consumption melting process, the vacuum degree is less than or equal to 3.0 Pa, the melting current is 22-32 kA, and the melting voltage is 26-40 V.

7. The method for controlling the compositional uniformity of TC32 titanium alloy ingots according to claim 1, characterized in that: In step two, during the third vacuum self-consumable melting, when the remaining weight of the self-consumable electrode is 200-300 kg, the stirring current is increased to compensate for shrinkage. After the compensation begins, the stirring current is gradually reduced, and the depth of the molten pool gradually decreases.

8. The method for controlling the compositional uniformity of TC32 titanium alloy ingots according to claim 1, characterized in that: In step two, the cooling time after the first vacuum self-consumption melting is greater than or equal to 5 hours, the cooling time after the second vacuum self-consumption melting is greater than or equal to 7 hours, and the cooling time after the third vacuum self-consumption melting is greater than or equal to 7 hours.

9. The method for controlling the compositional uniformity of TC32 titanium alloy ingots according to claim 1, characterized in that: In step one, at least two integral electrodes should be fabricated, with a density ranging from 3.4 to 3.8 g / cm³. 3 The length of a single integral electrode is 4.0 to 6.0 m.

10. The method for controlling the compositional uniformity of TC32 titanium alloy ingots according to claim 1, characterized in that: In step two, during the first vacuum consumable melting process, each integral electrode from step one is melted separately. Then, before the second vacuum consumable melting process, all the primary ingots are sequentially welded in the melting crucible crystallizer to form columnar ingots. During the welding process, the vacuum degree is less than or equal to 5.0 Pa, the welding current is 20-30 kA, and the welding voltage is 31-50 V.

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