A method for preparing a low segregation large-size titanium alloy ingot

Abstract

The application provides a preparation method of a low-segregation large-size titanium alloy ingot, and the preparation method comprises the following steps: welding titanium alloy electrode blocks after stacking to prepare a consumable electrode; and performing three times of vacuum consumable smelting on the consumable electrode to prepare a titanium alloy ingot; wherein the first time of vacuum consumable smelting comprises a first smelting stage under a first smelting current I1, the second time of vacuum consumable smelting comprises a second smelting stage under a second smelting current I2, and the third time of vacuum consumable smelting comprises a third smelting stage under a third smelting current I3, and I1, I2 and I3 satisfy the following relationship: I2 = I3 + (0.3-0.6) * I1, I1 = 8 KA-11 KA, and I3 = 12 KA-18 KA. The relationship among the three smelting currents is established, the head-bottom segregation of the titanium alloy generated in smelting is coordinated, the uniformity of the component distribution of the titanium alloy ingot is improved, and the quality loss is reduced.

Description

Technical Field

[0001] This application relates to the field of metal smelting technology, and in particular to a method for preparing large-size titanium alloy ingots with low segregation. Background Technology

[0002] Vacuum arc remelting (VAR) is the primary smelting method for producing high-quality titanium and titanium alloy ingots. To save costs, pure titanium and low-alloy titanium alloys for civilian use generally employ secondary VAR smelting. However, for titanium alloys used in more critical applications such as aerospace and nuclear power, standards typically require tertiary VAR smelting. In all smelting processes, titanium alloys are smelted by turning the ingot around before loading it into the furnace for the next smelting cycle. Therefore, secondary smelting is equivalent to melting from bottom to top and then from top to bottom, resulting in minimal compositional differences between the ingot's head and bottom. Tertiary smelting, however, is asymmetrical, with uneven melting at both ends of the ingot. For example, the head of the final ingot may have undergone two final melting cycles and one initial melting cycle compared to the bottom. This sequence of melting leads to different solidification times, affecting solute distribution. If an alloy ingot contains a large number of easily segregating elements, especially a certain amount of copper (Cu), iron (Fe), and chromium (Cr), the three most typical easily segregating alloying elements, it can easily cause a large difference in composition between the head and bottom of the ingot, resulting in obvious macroscopic segregation. This phenomenon is particularly pronounced when the ingot size increases, which seriously restricts the production and application of low-segregation large-size ingots. Summary of the Invention

[0003] Based on this, this application provides a method for preparing large-size titanium alloy ingots with low segregation, which improves the macroscopic compositional segregation problem of titanium alloy ingots containing easily segregating elements obtained by three melting processes.

[0004] This application provides a method for preparing large-size titanium alloy ingots with low segregation, comprising the following steps:

[0005] Titanium alloy electrode blocks are stacked and then welded to prepare consumable electrodes. The material of the titanium alloy electrode blocks includes, but is not limited to, titanium and segregated metal elements. The mass fraction of titanium in the material of the titanium alloy electrode blocks is 75% to 98%, and the segregated metals include one or more of copper (Cu), iron (Fe), and chromium (Cr).

[0006] The consumable electrode was subjected to three vacuum consumable melting processes to prepare a titanium alloy ingot with a diameter of 780 mm to 980 mm.

[0007] Specifically, the first vacuum arc remelting includes a first melting stage under a first melting current, the second vacuum arc remelting includes a second melting stage under a second melting current, and the third vacuum arc remelting includes a third melting stage under a third melting current.

[0008] The first smelting current is I1, the second smelting current is I2, and the third smelting current is I3. I1, I2, and I3 satisfy: I2 = I3 + (0.3 ~ 0.6) × I1, I1 = 8KA ~ 11KA, and I3 = 12KA ~ 18KA.

[0009] In one embodiment, the segregating element satisfies one or more of the following conditions:

[0010] (1) The weight percentage of copper in the titanium alloy electrode block is 0.5% to 3%;

[0011] (2) The weight percentage of iron in the titanium alloy electrode block is 1% to 3%;

[0012] (3) The weight percentage of chromium in the titanium alloy electrode block is 2% to 5%.

[0013] In one embodiment, the first melting voltage in the first melting stage is 22V to 23V; the second melting voltage in the second melting stage is 25V to 30V; and the third melting voltage in the third melting stage is 24V to 27V.

[0014] In one embodiment, the first vacuum arc remelting further includes a first arc ignition stage prior to the first remelting stage.

[0015] In one embodiment, the second vacuum arc remelting further includes a second arc ignition stage prior to the second remelting stage.

[0016] In one embodiment, the third vacuum arc remelting further includes a third arc initiation stage before the third remelting stage and a feeding stage after the third remelting stage.

[0017] In one embodiment, the conditions for the feeding stage include reducing the third melting current to 2kA to 6kA within 20 to 70 minutes and then maintaining it for 20 to 100 minutes.

[0018] In one embodiment, the conditions for the first arc initiation stage, the second arc initiation stage, and the third arc initiation stage each independently include increasing the current from 2kA to 6kA to the melting current within 5min to 30min.

[0019] In one embodiment, the segregated metal further includes one or more of aluminum, vanadium, tin, zirconium, tungsten, niobium, tantalum, and molybdenum.

[0020] In one embodiment, the titanium alloy ingot weighs between 5000 kg and 15000 kg.

[0021] By exploring the matching degree of the three melting currents to coordinate the compositional differences between the head and bottom of the finished titanium alloy ingot, the relationship between the second melting current and the first and third melting currents was established. This coordinated the head-bottom segregation phenomenon that occurs during the melting and solidification process of titanium alloy, resulting in minimal compositional differences between the head and bottom of the ingot after three melting processes. This improved the uniformity of the compositional distribution of the titanium alloy ingot, thereby enhancing the performance stability of subsequent products, improving product quality, and reducing quality loss. Attached Figure Description

[0022] Figure 1 Comparison diagram of elemental segregation of TB6 alloy ingots in Examples 1, 2, 1, 2 and 5. Detailed Implementation

[0023] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0025] The terms "preferred," "more preferably," etc., used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application.

[0026] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0027] When using “including,” “having,” and “contains” as described herein, the intention is to cover non-exclusive inclusion, unless an explicit qualifying term such as “only,” “consisting of,” etc., is used, in which case another component may be added.

[0028] Unless otherwise stated, a singular term may include a plural term and should not be understood as having a quantity of one.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] This application provides a method for preparing large-size titanium alloy ingots with low segregation, comprising the following steps:

[0031] Titanium alloy electrode blocks are stacked and then welded to prepare consumable electrodes. The material of the titanium alloy electrode blocks includes titanium and segregated metal elements. The mass fraction of titanium in the material of the titanium alloy electrode blocks is 75% to 98%. The segregated metals include one or more of copper (Cu), iron (Fe), and chromium (Cr).

[0032] The consumable electrode was subjected to three vacuum consumable melting processes to prepare titanium alloy ingots with a diameter of 780 mm to 980 mm.

[0033] Specifically, the first vacuum arc remelting includes a first melting stage under a first melting current, the second vacuum arc remelting includes a second melting stage under a second melting current, and the third vacuum arc remelting includes a third melting stage under a third melting current.

[0034] The first smelting current is I1, the second smelting current is I2, and the third smelting current is I3. I1, I2, and I3 satisfy: I2 = I3 + (0.3 ~ 0.6) × I1, I1 = 8KA ~ 11KA, I3 = 12KA ~ 18KA.

[0035] In some examples, in a method for preparing a large-sized titanium alloy ingot with low segregation, when the first, second, and third vacuum self-consumption melting processes are carried out, the diameter of the crucible used in the first, second, and third vacuum self-consumption melting stages is selected from 580 mm to 980 mm, and the diameter of the crucible increases progressively with the number of melting processes.

[0036] In some of these examples, the crucible diameter is selected from Φ580mm, Φ680mm, Φ780mm, Φ880mm, and Φ980mm.

[0037] Specifically, when a crucible with a specification of Φ680mm is used in the first melting stage, the crucible used in the second melting stage should have a specification of Φ780mm, and the crucible used in the third melting stage should have a specification of Φ880mm.

[0038] In some examples, the crucible diameter used in the third vacuum arc remelting is 780 mm to 980 mm. Specifically, the crucible diameter used in the third vacuum arc remelting can be, but is not limited to, 780 mm, 800 mm, 820 mm, 840 mm, 860 mm, 880 mm, 900 mm, 920 mm, 940 mm, 960 mm, or 980 mm.

[0039] Understandably, after the first and second vacuum arc remelting processes are completed, the ingots are turned around and loaded into the furnace before the next vacuum arc remelting process is carried out.

[0040] Specifically, I1, I2, and I3 may, but are not limited to, satisfy the following relationships: I2 = I3 + 0.3 × I1, I2 = I3 + 0.35 × I1, I2 = I3 + 0.4 × I1, I2 = I3 + 0.45 × I1, I2 = I3 + 0.5 × I1, I2 = I3 + 0.55 × I1, or I2 = I3 + 0.6 × I1.

[0041] The first melting current I1 can be, but is not limited to, 8KA, 9KA, 10KA or 11KA, and the third melting current I3 can be, but is not limited to, 12KA, 13KA, 14KA, 15KA, 16KA, 17KA or 18KA.

[0042] It can be understood that, according to the above formula, I2 > I3 > I1, and it can be calculated that the value range of I2 is 14.4KA to 24.6KA. The value relationships are listed below:

[0043] Table 1 lists some of the values ​​of the melting current in the three melting stages.

[0044]

[0045]

[0046] In some of these examples, the weight percentage of copper in the titanium alloy electrode block is 0.5% to 3%.

[0047] In some of these examples, the weight percentage of iron in the titanium alloy electrode block is 1% to 3%.

[0048] In some of these examples, the weight percentage of chromium in the titanium alloy electrode block is 2% to 5%.

[0049] Understandably, the segregated metals in the titanium alloy electrode block may also include one or more of aluminum, vanadium, tin, zirconium, tungsten, niobium, tantalum, and molybdenum.

[0050] In some examples, the first melting voltage in the first melting stage is 22V to 23V; the second melting voltage in the second melting stage is 25V to 30V; and the third melting voltage in the third melting stage is 24V to 27V.

[0051] It is understandable that the melting voltage itself has very little effect on the melting rate and solute segregation in vacuum melting, mainly affecting the arc stability during the melting process. Therefore, the melting voltage is set to match the crucible specifications and melting current to obtain relatively good and stable melting conditions. It should be noted that when using a larger crucible or a larger melting current, the melting voltage can generally be appropriately increased; of course, the voltage can also be kept constant.

[0052] In some examples, the titanium alloy ingot weighs between 5000 kg and 15000 kg, preferably between 64000 kg and 12000 kg. Specifically, the weight of the titanium alloy ingot can be, but is not limited to, 5000 kg, 6000 kg, 6400 kg, 7000 kg, 8000 kg, 9000 kg, 10000 kg, 10580 kg, 11000 kg, 12000 kg, 13000 kg, 14000 kg, or 15000 kg.

[0053] In some of these examples, the first vacuum arc remelting also includes a first arc ignition stage prior to the first remelting stage.

[0054] In some of these examples, the second vacuum arc remelting also includes a second arc initiation stage prior to the second remelting stage.

[0055] In some examples, the third vacuum arc remelting also includes a third arc initiation stage before the third remelting stage and a feeding stage after the third remelting stage.

[0056] In a specific example, the first vacuum arc remelting also includes a first arc initiation stage before the first remelting stage.

[0057] Specifically, the first vacuum self-consumable melting process includes the first arc-starting stage and the first melting stage.

[0058] In one specific example, the second vacuum arc remelting also includes a second arc initiation stage prior to the second remelting stage.

[0059] Specifically, the second vacuum self-consumable melting process includes a second arc-starting stage and a second melting stage.

[0060] In a specific example, the third vacuum arc remelting also includes a third arc initiation stage before the third remelting stage and a shrinkage stage after the third remelting stage.

[0061] Specifically, the third vacuum self-consumption melting process includes the third arc initiation stage, the third melting stage, and the feeding stage.

[0062] In a specific example, the conditions for the first arc initiation stage, the second arc initiation stage, and the third arc initiation stage each independently include a current of 2kA to 6kA being increased to the melting current within 5 to 30 minutes.

[0063] Furthermore, the conditions for the first arc initiation stage, the second arc initiation stage, and the third arc initiation stage each independently include increasing the current from 3kA to 4kA to the melting current within 10min to 30min.

[0064] In a specific example, the conditions for the feeding stage include reducing the third melting current to 2kA to 6kA within 20 to 70 minutes and then maintaining it for 20 to 100 minutes.

[0065] Furthermore, when the consumable electrode is melted down to a remaining weight of 150Kg to 200Kg, it enters the feeding stage. The conditions for the feeding stage include the third melting current being reduced to 3kA to 4kA within 30min to 60min and then maintained for 30min to 90min.

[0066] In some of these embodiments, the titanium alloy ingots are TB6 alloy (nominal composition Ti-10V-2Fe-3Al), TC17 alloy (nominal composition Ti-5Al-2Sn-2Zr-4Mo-4Cr), and TA13 alloy (nominal composition Ti-2.5Cu) as specified in GB 3620.1.

[0067] By exploring the matching degree of the three melting currents to coordinate the compositional differences between the top and bottom of the finished titanium alloy ingot, the relationship between the second melting current and the first and third melting currents was established. This coordinated the genetic segregation phenomenon that occurs during the melting and solidification process of titanium alloy. As a result, after three melting processes, while maintaining a small difference in composition between the edge and center of the ingot, the compositional differences between the top and bottom of the ingot were further minimized. This improved the uniformity of the overall compositional distribution of the titanium alloy ingot, thereby enhancing the performance stability of subsequent products, improving product quality, and reducing quality losses.

[0068] The following specific embodiments further illustrate the titanium alloy ingot of this application in detail. Other preparation parameters not mentioned in each embodiment remain consistent in all embodiments.

[0069] Example 1: A TB6 (nominal composition Ti-10V-2Fe-3Al) titanium alloy ingot with a target specification of Φ880mm was obtained by three vacuum arc remelting processes, wherein the three vacuum arc remelting processes included:

[0070] A 10580kg consumable electrode was prepared by stacking and welding TB6 electrode blocks weighing 92kg each and with a diameter of Φ580mm. The consumable electrode was then melted three times in a vacuum consumable arc furnace. In the first melting stage, the crucible diameter was Φ680mm, the melting current (I1) during normal melting was 9KA, and the melting voltage was 22.5V. In the second melting stage, the crucible diameter was Φ780mm, and the melting current (I2) during normal melting was 17.7KA (i.e., ...). I2 = I3 + 0.3 × I1), the melting voltage is 26V; turn around and start the third melting, the crucible diameter of the third melting (finished product melting) is Φ880mm, the melting current (I3) of the normal melting stage is 15KA, the melting voltage is 25V; when the remaining weight of the self-consumable electrode is melted to 160Kg, it enters the feeding stage. The current of the feeding stage is reduced from the normal melting current to 3.5KA within 50min, and is maintained for 60min. Then the circuit breaker trips to end the melting and the finished ingot is obtained.

[0071] Samples were taken from the ingot body at a distance of 250 mm from the head and bottom faces, after peeling off 10 mm of the ingot surface, to test the content of alloying elements in the ingot. The average value of three tests was taken, and the V, Fe, and Al content at the head / bottom of the ingot was found to be 9.82% / 9.81%, 1.99% / 1.96%, and 2.98% / 3.00%, respectively. This means the head-to-bottom differences in V, Fe, and Al were 0.01%, 0.03%, and -0.02%, respectively. Simultaneously, the ingot was sawn in half, and samples were taken from the center and edges of the sawn surfaces. The edge-to-center differences in V, Fe, and Al were found to be -0.02%, -0.06%, and 0.02%, respectively.

[0072] Example 2

[0073] The difference between this embodiment and Embodiment 1 is that the relationship between the smelting currents is I2 = I3 + 0.6 × I1.

[0074] The TB6 (nominal composition Ti-10V-2Fe-3Al) titanium alloy ingot with a target specification of Φ880mm was obtained by three vacuum arc remelting processes, which included:

[0075] A 10580kg consumable electrode was prepared by stacking and welding TB6 electrode blocks weighing 92kg each and with a diameter of Φ580mm. The consumable electrode was then melted three times in a vacuum consumable arc furnace. In the first melting stage, the crucible diameter was Φ680mm, the melting current (I1) during normal melting was 9kA, and the melting voltage was 22.5V. In the second melting stage, the crucible diameter was Φ780mm, and the melting current (I2) during normal melting was 20.4kA (i.e., ...). I2 = I3 + 0.6 × I1), the melting voltage is 26V; turn around and perform the third melting, the crucible diameter of the third melting (finished product melting) is Φ880mm, the melting current (I3) of the normal melting stage is 15KA, the melting voltage is 25V; when the remaining weight of the consumable electrode is melted to 160Kg, it enters the feeding stage. The current of the feeding stage is reduced from the normal melting current to 3.5KA within 50min, and is maintained for 60min. Then the circuit breaker trips to end the melting and the finished ingot is obtained.

[0076] Samples were taken from the ingot body at a distance of 250 mm from the head and bottom faces, after peeling off 10 mm of the ingot surface, to test the content of alloying elements in the ingot. The average value of three tests was taken, and the V, Fe, and Al content at the head / bottom of the ingot was found to be 9.88% / 9.89%, 2.01% / 2.05%, and 3.07% / 3.05%, respectively. This means the head-to-bottom differences in V, Fe, and Al were -0.01%, -0.04%, and 0.02%, respectively. Simultaneously, the ingot was sawn in half, and samples were taken from the center and edges of the sawn surfaces. The edge-to-center differences in V, Fe, and Al were found to be -0.02%, -0.06%, and 0.02%, respectively.

[0077] Example 3: A TA13 alloy (nominal composition Ti-2.5Cu) ingot with a target specification of Φ780mm was obtained by three vacuum arc remelting processes, wherein the three vacuum arc remelting processes included:

[0078] A 6400kg consumable electrode was prepared by stacking and welding TA13 electrode blocks weighing 64kg each and with a diameter of Φ480mm. The consumable electrode was then melted three times in a vacuum consumable arc furnace. In the first melting stage, the crucible diameter was Φ580mm, the melting current (I1) during normal melting was 8KA, and the melting voltage was 22V. The furnace was then turned around for a second melting stage, with a crucible diameter of Φ680mm and a melting current (I2) of 15.6KA during normal melting (i.e., I2...). =I3+0.45×I1), the melting voltage is 25.5V; turn around and carry out the third melting, the crucible diameter of the third melting (finished product melting) is Φ780mm, the melting current (I3) of the normal melting stage is 12KA, and the melting voltage is 24V; when the remaining weight of the self-consumable electrode is melted to 150Kg, it enters the feeding stage. The current of the feeding stage is reduced from the normal melting current to 3KA within 40min, and is maintained for 60min. Then the circuit breaker trips to end the melting and the finished ingot is obtained.

[0079] Samples were taken from the ingot body at a distance of 250 mm from the head and bottom faces, after peeling off 10 mm of the ingot surface, to test the content of alloying elements in the ingot. The average value of three tests was taken, and the Cu content at the head / bottom was found to be 2.55% / 2.52%, meaning the head-to-bottom Cu difference was 0.03%. Simultaneously, the ingot was sawn in half, and samples were taken from the center and edge of the sawn surface, revealing an edge-to-center Cu difference of -0.06%.

[0080] Example 4: A TC17 alloy (nominal composition Ti-5Al-2Sn-2Zr-4Mo-4Cr) titanium alloy ingot with a target specification of Φ980mm was obtained by three vacuum arc remelting processes, wherein the three vacuum arc remelting processes included:

[0081] A 12000kg consumable electrode was prepared by stacking and welding TC17 electrode blocks, each weighing 120kg and with a diameter of Φ680mm. The consumable electrode was then melted three times in a vacuum consumable arc furnace. In the first melting stage, the crucible diameter was Φ780mm, the melting current (I1) during normal melting was 11kA, and the melting voltage was 23V. In the second melting stage, the crucible diameter was Φ880mm, and the melting current (I2) during normal melting was 24.6kA (i.e.,...). I2 = I3 + 0.6 × I1), the melting voltage is 30V; turn around and perform the third melting, the crucible diameter of the third melting (finished product melting) is Φ980mm, the melting current (I3) of the normal melting stage is 18KA, the melting voltage is 26V; when the remaining weight of the self-consumable electrode is melted to 180Kg, it enters the feeding stage. The current of the feeding stage is reduced from the normal melting current to 4KA within 50min, and is maintained for 60min. Then the circuit breaker trips to end the melting and the finished ingot is obtained.

[0082] Samples were taken from the ingot body at a distance of 250 mm from the head and bottom faces of the ingot, after peeling off 10 mm of the surface layer, to test the content of alloying elements in the ingot. The average value of three tests was taken, and the contents of Al, Sn, Zr, Mo, and Cr at the head and bottom of the ingot were found to be 5.08% / 5.10%, 2.13% / 2.13%, 1.99% / 1.97%, 4.06% / 4.09%, and 4.05% / 4.00%, respectively. This means the head-to-bottom differences in Al, Sn, Zr, Mo, and Cr were -0.02%, 0%, 0.02%, -0.03%, and 0.05%, respectively. Meanwhile, the ingot was sawn in half, and samples were taken from the core and edge of the sawn surface. The edge-to-core difference (edge-to-core) of Al, Sn, Zr, Mo and Cr was measured to be 0.03%, 0.01%, -0.04%, 0.04% and -0.07%, respectively.

[0083] Comparative Example 1: The preparation process of Comparative Example 1 is basically the same as that of Example 1, except that the melting current (I2) in the normal melting stage of the second melting is 15KA (i.e., I2 = I3 + 0 × I1).

[0084] The V, Fe, and Al content of the prepared ingot head / bottom was 9.90% / 9.87%, 2.07% / 1.97%, and 2.90% / 2.96%, respectively, meaning the head-to-bottom differences in V, Fe, and Al were 0.03%, 0.10%, and -0.06%, respectively. Simultaneously, the edge-to-center differences in V, Fe, and Al on the cross-section at the middle of the ingot were measured to be -0.02%, -0.06%, and 0.02%, respectively.

[0085] Comparative Example 2: The preparation process of Comparative Example 2 is basically the same as that of Example 2, except that the melting current (I2) in the normal melting stage of the second melting is 23.1KA (i.e., I2 = I3 + 0.9 × I1).

[0086] The V, Fe, and Al content of the prepared ingot head / bottom was 10.02% / 10.06%, 2.02% / 2.14%, and 3.08% / 3.02%, respectively, meaning the head-to-bottom differences in V, Fe, and Al were -0.04%, -0.12%, and 0.06%, respectively. Simultaneously, the edge-to-center differences in V, Fe, and Al on the cross-section at the center of the ingot were measured to be -0.02%, -0.06%, and 0.02%, respectively.

[0087] Comparative Example 3: The preparation process of Comparative Example 3 is basically the same as that of Example 3, except that the melting current (I2) in the normal melting stage of the second melting is 24KA (i.e., I2 = I3 + 0.9 × I1).

[0088] The Cu content of the prepared ingot head / bottom was 2.45% / 2.55%, respectively, meaning the Cu content difference between the head and bottom was -0.10%. Simultaneously, the Cu content difference between the edge and center (edge ​​to center) on the cross-section of the ingot's middle section was measured to be -0.06%.

[0089] Comparative Example 4: The preparation process of Comparative Example 4 is basically the same as that of Example 4, except that the melting current (I2) in the normal melting stage of the second melting is 18KA (i.e., I2 = I3 + 0 × I1).

[0090] The contents of Al, Sn, Zr, Mo, and Cr in the prepared ingot head / bottom were 5.00% / 5.08%, 2.10% / 2.06%, 2.02% / 1.96%, 4.04% / 4.13%, and 4.11% / 3.97%, respectively. This means the head-to-bottom differences in Al, Sn, Zr, Mo, and Cr were -0.08%, 0.04%, 0.06%, -0.09%, and 0.14%, respectively. Simultaneously, the edge-to-center differences in Al, Sn, Zr, Mo, and Cr on the cross-section at the center of the ingot were measured to be 0.03%, 0.01%, -0.04%, 0.04%, and -0.07%, respectively.

[0091] Comparative Example 5: The preparation process of Comparative Example 5 is basically the same as that of Example 1, except that the melting current (I2) in the normal melting stage of the second melting is 12.3KA (i.e., I2 = I3 - 0.3 × I1).

[0092] The V, Fe, and Al content of the prepared ingot head / bottom was 10.07% / 10.02%, 2.13% / 1.98%, and 3.00% / 3.08%, respectively, meaning the head-to-bottom differences in V, Fe, and Al were 0.05%, 0.15%, and -0.08%, respectively. Simultaneously, the edge-to-center differences in V, Fe, and Al on the cross-section at the center of the ingot were measured to be -0.02%, -0.06%, and 0.02%, respectively.

[0093] It is evident that by exploring the matching degree of the three melting currents to coordinate the compositional differences between the head and bottom of the finished titanium alloy ingot, establishing the relationship between the second melting current and the first and third melting currents, and further optimizing the melting conditions according to the composition of the titanium alloy, the inherited segregation phenomenon of the head and bottom of the titanium alloy during the melting and solidification process was coordinated without changing the edge-center segregation of the ingot. This resulted in a very small compositional difference between the head and bottom of the ingot after three melting processes, improving the uniformity of the compositional distribution of the entire titanium alloy ingot, thereby improving the performance stability of subsequent products, enhancing product quality, and reducing quality loss.

[0094] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0095] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A method for preparing a large-size titanium alloy ingot with low segregation, characterized in that, Includes the following steps: Titanium alloy electrode blocks are stacked and then welded to prepare consumable electrodes; the material of the titanium alloy electrode blocks includes titanium and segregated metal elements, wherein the mass fraction of titanium in the material of the titanium alloy electrode blocks is 75% to 98%, and the segregated metal includes one or more of copper, iron and chromium. The consumable electrode was subjected to three vacuum consumable melting processes to prepare titanium alloy ingots with a diameter of 780 mm to 980 mm. Specifically, the first vacuum arc remelting includes a first melting stage under a first melting current, the second vacuum arc remelting includes a second melting stage under a second melting current, and the third vacuum arc remelting includes a third melting stage under a third melting current. The first smelting current is I1, the second smelting current is I2, and the third smelting current is I3. I1, I2, and I3 satisfy: I2 = I3 + (0.3~0.6) × I1, I1 = 8 KA ~ 11 KA, I3 = 12 KA ~ 18 KA.

2. The method for preparing low-segregation large-size titanium alloy ingots as described in claim 1, characterized in that, The segregated metallic element satisfies one or more of the following conditions: (1) The weight percentage of copper in the titanium alloy electrode block is 0.5% to 3%; (2) The weight percentage of iron in the titanium alloy electrode block is 1% to 3%; (3) The weight percentage of chromium in the titanium alloy electrode block is 2% to 5%.

3. The method for preparing low-segregation large-size titanium alloy ingots as described in claim 1, characterized in that, The first melting stage has a first melting voltage of 22 V ~ 23 V; the second melting stage has a second melting voltage of 25 V ~ 30 V; and the third melting stage has a third melting voltage of 24 V ~ 27 V.

4. The method for preparing low-segregation large-size titanium alloy ingots as described in claim 1, characterized in that, The first vacuum self-consumable melting also includes a first arc-starting stage before the first melting stage.

5. The method for preparing low-segregation large-size titanium alloy ingots as described in claim 4, characterized in that, The conditions for the first arc initiation stage include increasing the current from 2kA to 6kA to the melting current within 5 to 30 minutes.

6. The method for preparing low-segregation large-size titanium alloy ingots as described in claim 1, characterized in that, The second vacuum self-consumable melting also includes a second arc-starting stage before the second melting stage.

7. The method for preparing low-segregation large-size titanium alloy ingots as described in claim 6, characterized in that, The conditions for the second arc initiation stage include increasing the current from 2kA to 6kA to the melting current within 5 to 30 minutes.

8. The method for preparing low-segregation large-size titanium alloy ingots as described in claim 1, characterized in that, The third vacuum self-consuming melting process also includes a third arc-starting stage before the third melting stage and a shrinkage stage after the third melting stage.

9. The method for preparing low-segregation large-size titanium alloy ingots as described in claim 8, characterized in that, The conditions for the feeding stage include reducing the third melting current to 2kA to 6kA within 20 min to 70 min and then maintaining it for 20 min to 100 min.

10. The method for preparing low-segregation large-size titanium alloy ingots as described in claim 8, characterized in that, The conditions for the third arc initiation stage include increasing the current from 2kA to 6kA to the melting current within 5 to 30 minutes.

11. The method for preparing low-segregation large-size titanium alloy ingots as described in claim 1, characterized in that, The segregated metals also include one or more of aluminum, vanadium, tin, zirconium, tungsten, niobium, tantalum, and molybdenum.

12. The method for preparing low-segregation large-size titanium alloy ingots as described in claim 1, characterized in that, The titanium alloy ingot weighs between 5000 kg and 15000 kg.

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