Vacuum consumable melting method for titanium alloy cast ingot containing refractory elements

Abstract

The invention discloses a vacuum consumable smelting method for a titanium alloy cast ingot containing refractory elements, and belongs to the technical field of titanium alloys. The invention provides a vacuum consumable smelting method for a titanium alloy cast ingot containing refractory elements in order to solve the problems that as the melting points and the densities of the refractory elements such as W, Mo and Zr of a titanium alloy are obviously different from those of sponge titanium, the alloy of the cast ingot is not melted, and components are not uniform. Comprising the following steps: uniformly mixing refractory element ingredients, carrying out compression molding, carrying out vacuum sintering to obtain an intermediate alloy core rod, pressing titanium sponge and other raw materials into electrode blocks with semicircular recesses, stacking the electrode blocks into a cylinder with a central through hole, inserting the intermediate alloy core rod into the cylinder, welding to form a complete consumable electrode, and finally smelting. According to the method, the adding mode of the refractory elements is changed, and the vacuum consumable smelting parameters are optimized, so that the risk that incomplete alloy particles exist in the conventional smelting process of the titanium alloy containing the refractory elements is eliminated, and the distribution uniformity of the refractory elements in the cast ingot is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of titanium alloys, and particularly relates to a vacuum consumable melting method for a titanium alloy ingot containing refractory elements. Background Art

[0002] Due to characteristics such as low density, high specific strength, excellent high-temperature strength and creep resistance, titanium alloys are widely used in the aerospace field, such as airframe structural components and aero-engines. However, with the rapid development of advanced aircraft, the industry's demand for high-temperature materials is increasing day by day, and high-temperature titanium alloys with higher heat resistance have become the focus of current research.

[0003] Elements such as tungsten (W), molybdenum (Mo), and zirconium (Zr) have high melting points and low diffusivities, can significantly enhance the thermal stability of the microstructure of titanium alloys, and the ability to resist dislocation movement at high temperatures, and are regarded as ideal alloying elements for improving the high-temperature performance of titanium alloys. TC25 (Ti-6.5Al-2Mo-2Zr-2Sn-1W) is a typical high-temperature titanium alloy containing refractory elements developed therefrom. Its working time at 500 °C reaches 6000 h, and its working time at 550 °C reaches 3000 h, far exceeding the applicable temperature and service time of ordinary titanium alloys such as Ti-6Al-4V. At present, when TC25 is melted by vacuum consumable (VAR), the main method of adding alloying elements is that after alloy powder, massive master alloy, sponge titanium and other raw materials are mixed, they are pressed into electrodes, and then charged into a crucible and melted into an ingot. However, due to the obvious differences in the melting points, densities of refractory elements and their alloys and sponge titanium (the melting point of tungsten powder is 3422 °C, and the density is 19.35 g·cm -3 ; the melting point of sponge titanium is 1668 °C, and the density is 4.5 g·cm -3 )), there is a high probability that unmelted alloy particles and local composition inhomogeneity exist during the ingot melting process, thus deteriorating the mechanical properties of the material and being unfavorable for the further popularization and application of products.

[0004] CN117144188A discloses a method for preparing TiAl alloy by induction hot pressing sintering of elemental powders. Ti powder, Al powder and other elemental powders are loaded into a ball milling tank for vacuum low-energy ball milling and powder mixing to obtain uniformly mixed powders. CN119876868A discloses a high-density titanium-based alloy rotating target bonded to the outer side of a titanium-based back tube, which mixes metallic titanium and refractory elemental simple substances with melting points higher than that of metallic titanium into powders. CN104674034A discloses a ternary intermediate alloy of aluminum, tungsten and niobium, which uses A1, WO3, and Nb2O5 as raw materials. After mixing, a ternary intermediate alloy ingot of aluminum, tungsten and niobium is obtained through thermite reaction. CN117051286A discloses a method for preparing a special titanium alloy for PBF additive manufacturing, which uniformly mixes pure titanium powder and other elements required for preparing a customized titanium alloy in the form of intermediate alloy powder or elemental powder to obtain titanium alloy raw material powder. CN112410613A discloses a method for melting titanium alloy. The steps include: Step 1: Put sponge titanium and Nb bars into a mold to press an electrode block, and assemble and weld the pressed electrode blocks into a consumable electrode; Step 2: Perform primary melting on the consumable electrode prepared in Step 1, and obtain a primary ingot after cooling; Step 3: Invert the primary ingot obtained in Step 2 as a consumable electrode, perform secondary melting, and obtain a secondary ingot after cooling; Step 4: Process the secondary ingot obtained in Step 3 into Ti-Nb strips; Step 5: Select other required raw materials according to the elements in the alloy; calculate the weights of the required raw materials, mix them evenly, put them together with sponge titanium and the Ti-Nb strips obtained in Step 4 into a mold to press an electrode block, and assemble and weld the pressed electrode blocks into a consumable electrode.

[0005] It can be seen that most of the existing technologies directly mix raw materials, and it is difficult to overcome problems such as unmelted and uneven composition of ingot alloys caused by high melting points and large densities of refractory elements and their alloys. Summary of the Invention

[0006] To solve the above problems, the present invention develops a method for adding refractory elements to a titanium alloy to prepare a high-quality titanium alloy ingot. This method eliminates the risk of unmelted refractory element alloy particles during the ingot melting process by making the refractory elements into sintered mandrels and inserting them into the middle of the sponge titanium consumable electrode, and improves the distribution uniformity of the refractory elements in the titanium alloy ingot.

[0007] The present invention provides a vacuum consumable melting method for a titanium alloy ingot containing refractory elements, which includes the following steps: A. Prepare an intermediate alloy mandrel containing refractory elements: According to the composition of the titanium alloy, take appropriate amounts of refractory element metal powder and Ti powder, and through batching and mixing - pressing into shape - vacuum sintering, obtain an intermediate alloy mandrel; the refractory element metal powder is at least one of W powder, Mo powder or Zr powder; B. Preparation of a semi-cylindrical electrode block of titanium sponge without refractory elements: According to the titanium alloy composition, take appropriate amounts of titanium sponge and the remaining master alloys for batching and mixing, and press them into a semi-cylindrical electrode block with a semi-circular depression. C. Preparation of a consumable electrode: Stack a number of semi-cylindrical electrode blocks with semi-circular depressions into a cylinder with a central through-hole, insert a master alloy core rod into the central through-hole, and then weld the stacked electrode blocks and the core rod to form a complete consumable electrode; the diameter of the central through-hole of the consumable electrode is 20 - 100 mm, and the diameter of the master alloy core rod is 2 - 10 mm smaller than the diameter of the central through-hole; the length of the master alloy core rod is the same as that of the consumable electrode. D. Vacuum consumable arc furnace melting: Load the complete consumable electrode into a vacuum consumable arc furnace for 2 - 3 times of melting to obtain a titanium alloy ingot containing refractory elements with uniform alloy composition distribution.

[0008] Among them, in the above vacuum consumable melting method, the titanium alloy containing refractory elements is TA10 - TA12, TA14 - TA15, TA22, TA24, TA30 - TA35, TB2 - TB4, TB7 - TB11, TB15 - TB17, TC6 - TC9, TC11 - TC12, TC16 - TC19, TC21, TC23 - TC24, TC24 or TC27 - TC32. Of course, in the art, other titanium alloys containing refractory elements such as W, Mo, Zr, etc. are also applicable to the method of the present invention, and will not be listed one by one here.

[0009] Among them, in the above vacuum consumable melting method, in step A, the specific process of batching and mixing is as follows: Mix the refractory element metal powder and Ti powder with absolute ethanol, put in grinding balls, and carry out ball milling under inert gas protection to obtain a master alloy mixing slurry.

[0010] Preferably, in the above vacuum consumable melting method, in step A, when batching and mixing, the refractory element metal powder is W powder, Mo powder and Zr powder, and the master alloy mixing slurry is a W - Mo - Zr - Ti master alloy mixing slurry.

[0011] Among them, in the above vacuum consumable melting method, in step A, when batching and mixing, the ratio of the mass of absolute ethanol to the total mass of the refractory element metal powder and Ti powder is 1 - 5:1.

[0012] Among them, in the above vacuum consumable melting method, in step A, when batching and mixing, the ratio of the mass of the grinding balls to the total mass of the refractory element metal powder and Ti powder is 0.5 - 2:1.

[0013] Among them, in the above vacuum consumable melting method, in step A, when batching and mixing, the rotation speed of the ball milling is 100 - 200 r / min.

[0014] Among them, in the above vacuum consumable melting method, in step A, when the ingredients are mixed evenly, the ball milling time is 1 to 5 h.

[0015] Among them, in the above vacuum consumable melting method, in step A, the specific process of pressing and forming is as follows: after drying the mixed slurry of the intermediate alloy after mixing the ingredients evenly, put it into a cylindrical mold, and apply a pressure of 100 to 200 MPa to press and form to obtain a green compact.

[0016] Among them, in the above vacuum consumable melting method, in step A, the specific process of vacuum sintering is as follows: under a vacuum degree less than 20 Pa, heat the green compact after pressing and forming in the furnace at a heating rate of 2 to 5 °C / min to 1200 to 1400 °C, then keep it warm for 4 to 6 h, and then cool it to room temperature in the furnace to obtain an intermediate alloy core rod.

[0017] Preferably, in the above vacuum consumable melting method, in step A, the intermediate alloy core rod obtained by vacuum sintering is a W-Mo-Zr-Ti intermediate alloy core rod.

[0018] Among them, in the above vacuum consumable melting method, in step B, the pressure for pressing is 25 to 30 MPa, and the pressure holding time is 5 to 10 s.

[0019] Among them, in the above vacuum consumable melting method, in step D, the parameters of the first melting are as follows: the vacuum degree before power-on < 2.0 Pa, the leakage rate < 0.8 Pa / min, the AC stable arc current is 5 to 7 A, the AC alternating time is 20 to 30 s, the stable melting voltage is 30 to 40 V, and the stable melting current is 10 to 15 kA.

[0020] Among them, in the above vacuum consumable melting method, in step D, the parameters of the second melting are as follows: the vacuum degree before power-on < 2.0 Pa, the leakage rate < 0.8 Pa / min, the AC stable arc current is 8 to 10 A, the AC alternating time is 10 to 20 s, the stable melting voltage is 30 to 40 V, and the stable melting current is 15 to 25 kA.

[0021] Among them, in the above vacuum consumable melting method, in step D, the parameters of the third melting are as follows: the vacuum degree before power-on < 1.0 Pa, the leakage rate < 0.6 Pa / min, the AC stable arc current is 10 to 15 A, the AC alternating time is 10 to 20 s, the stable melting voltage is 30 to 40 V, and the stable melting current is 20 to 30 kA.

[0022] The beneficial effects of the present invention: By prefabricating refractory elements (such as W, Mo, Zr, etc.) into sintered mandrels and inserting them into the center of the sponge titanium electrode, and cooperating with optimized vacuum consumable melting parameters, the present invention successfully eliminates the risk of unmelted alloy particles existing in the conventional melting process of titanium alloys containing refractory elements, and significantly improves the distribution uniformity of refractory elements in the ingot. This uniform microstructure can ensure that the titanium alloy maintains stable hot strength and heat resistance at high temperatures (such as 550 °C), meeting the high-performance requirements of key components such as compressor disks and blades of aerospace engines. The present invention can provide a reusable melting process paradigm for many titanium alloys containing refractory elements (such as Ti65, TA33, etc.). BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flowchart of vacuum consumable melting of an ingot of a titanium alloy containing refractory elements according to the present invention.

[0024] Figure 2 It is a schematic diagram of a semi-cylindrical electrode block with a semi-circular depression.

[0025] Figure 3 It is a schematic diagram of a consumable electrode inserted with a refractory element intermediate alloy mandrel.

[0026] Figure 4 It is a schematic diagram of the sampling positions at 12 o'clock on the side of the ingot.

[0027] Figure 5 It is a micro-area morphology diagram inside the ingot; among them, a is Example 1 and b is Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0028] Specifically, a method for vacuum consumable melting of an ingot of a titanium alloy containing refractory elements includes the following steps: A. Prepare an intermediate alloy mandrel containing refractory elements: According to the composition of the titanium alloy, take appropriate amounts of refractory element metal powder and Ti powder, and after batching and mixing (usually in a ball mill for batching and mixing) - compacting - vacuum sintering (usually in a high-temperature vacuum furnace for vacuum sintering), obtain an intermediate alloy mandrel; the refractory element metal powder is at least one of W powder, Mo powder or Zr powder; B. Prepare a sponge titanium semi-cylindrical electrode block without refractory elements: According to the composition of the titanium alloy, take appropriate amounts of sponge titanium and the remaining intermediate alloys for batching and mixing, and press them into a semi-cylindrical electrode block with a semi-circular depression; C. Prepare a consumable electrode: Stack a number of semi-cylindrical electrode blocks with semi-circular depressions into a cylinder with a central through hole, insert the intermediate alloy mandrel into the central through hole, and then weld the stacked electrode blocks and the mandrel to form a complete consumable electrode; the diameter of the central through hole of the consumable electrode is 20 - 100 mm, and the diameter of the intermediate alloy mandrel is 2 - 10 mm smaller than the diameter of the central through hole; the length of the intermediate alloy mandrel is the same as that of the consumable electrode; D. Vacuum consumable arc furnace melting: Load the complete consumable electrode into a vacuum consumable arc furnace for 2 - 3 times of melting to obtain a titanium alloy ingot containing refractory elements with uniform alloy composition distribution.

[0029] In this field, there are many types of titanium alloys containing refractory elements W, Mo, and Zr. One can refer to the standard GBT3620.1 - 2016. And many types of titanium alloys are not within this standard but also contain the three elements W, Mo, and Zr. Therefore, those skilled in the art can determine the titanium alloys containing refractory elements W, Mo, and Zr according to their needs. The method of the present invention can also solve the problems brought by the refractory elements in these titanium alloys containing W, Mo, and Zr. For example, in the present invention, the titanium alloy containing refractory elements can be TA10 - TA12, TA14 - TA15, TA22, TA24, TA30 - TA35, TB2 - TB4, TB7 - TB11, TB15 - TB17, TC6 - TC9, TC11 - TC12, TC16 - TC19, TC21, TC23 - TC24, TC24 or TC27 - TC32. After determining the type of titanium alloy in the present invention, according to the composition of this titanium alloy, those skilled in the art can determine the dosages of the refractory element metal powder and Ti powder in step A.

[0030] In step B of the present invention, the remaining master alloys refer to the master alloys of other elements in the composition of this titanium alloy except for Ti and refractory elements (including W, Mo, Zr). For example, in the embodiment of the present invention, the TC25 titanium alloy also contains Al and Sn, so the master alloy containing Al and Sn needs to be added. After those skilled in the art determine the type of titanium alloy, according to the composition of this titanium alloy, they can determine the addition of the remaining master alloys in step B.

[0031] In the present invention, the diameter of the central through - hole of the consumable electrode is controlled to be 20 - 100 mm, and the diameter of the master alloy core rod is 2 - 10 mm smaller than the diameter of the central through - hole. After those skilled in the art determine the type of titanium alloy, they can comprehensively consider the composition of the titanium alloy, as well as the diameter and length of the master alloy core rod, the outer diameter of the consumable electrode, and the diameter and length of the intermediate through - hole, and then determine how to allocate the dosage of Ti in step A and step B, as long as the target titanium alloy composition can be obtained.

[0032] In step A of the present invention, the specific process of mixing the ingredients evenly is: Mix the refractory element metal powder and Ti powder with absolute ethanol, put in grinding balls, and carry out ball - milling under inert gas protection to obtain a uniformly mixed slurry of master alloy.

[0033] In the present invention, refractory elements are prefabricated into sintered mandrels and inserted into the sponge titanium electrodes, which solves the problems brought by refractory elements. Therefore, the present invention is more suitable for preparing titanium alloys containing W powder, Mo powder and Zr at the same time. Therefore, in step A, when the ingredients are mixed evenly, the refractory element metal powders are preferably W powder, Mo powder and Zr powder, and the obtained intermediate alloy mixed slurry is the W-Mo-Zr-Ti intermediate alloy mixed slurry.

[0034] In step A of the present invention, when the ingredients are mixed evenly, the ratio of the mass of absolute ethanol to the total mass of the refractory element metal powders and Ti powder is 1-5:1.

[0035] In step A of the present invention, when the ingredients are mixed evenly, the ratio of the mass of the grinding balls to the total mass of the refractory element metal powders and Ti powder is 0.5-2:1.

[0036] In step A of the present invention, when the ingredients are mixed evenly, the rotation speed of the ball milling is 100-200 r / min.

[0037] In step A of the present invention, when the ingredients are mixed evenly, the ball milling time is 1-5 h.

[0038] In step A of the present invention, the specific process of pressing and forming is as follows: after drying the intermediate alloy mixed slurry after mixing the ingredients evenly, it is put into a cylindrical mold, and a pressure of 100-200 MPa is applied, and it is molded by die pressing to obtain a green compact.

[0039] In step A of the present invention, the specific process of vacuum sintering is as follows: under a vacuum degree of less than 20 Pa, the green compact after pressing and forming is heated in the furnace at a heating rate of 2-5 °C / min to 1200-1400 °C, then kept warm for 4-6 h, and then cooled to room temperature in the furnace to obtain an intermediate alloy mandrel.

[0040] In step B of the present invention, the pressure of the pressing is 25-30 MPa, and the pressure holding time is 5-10 s. After determining the type of titanium alloy in the present invention, those skilled in the art can determine the types and dosages of the remaining intermediate alloys in step B according to the composition of the titanium alloy.

[0041] In step D of the present invention, the parameters of the first melting are as follows: the vacuum degree before power-on < 2.0 Pa, the leakage rate < 0.8 Pa / min, the AC arc stabilizing current 5-7 A, the AC alternating time 20-30 s, the stable melting voltage 30-40 V, and the stable melting current 10-15 kA.

[0042] In step D of the present invention, the parameters of the second melting are as follows: the vacuum degree before power-on < 2.0 Pa, the leakage rate < 0.8 Pa / min, the AC arc stabilizing current 8-10 A, the AC alternating time 10-20 s, the stable melting voltage 30-40 V, and the stable melting current 15-25 kA.

[0043] In step D of the present invention, the parameters for the third melting are as follows: the vacuum degree before power-on is < 1.0 Pa, the leakage rate is < 0.6 Pa / min, the AC arc stabilizing current is 10 - 15 A, the AC alternating time is 10 - 20 s, the stable melting voltage is 30 - 40 V, and the stable melting current is 20 - 30 kA.

[0044] In the present invention, according to different equipment, processes, and weights of the smelted titanium alloy, the ranges of the outer diameter and length of the semi-cylindrical electrode block with a semi-circular depression fluctuate greatly, generally with the outer diameter ranging from 100 mm to 1000 mm. Those skilled in the art can control according to the actual situation.

[0045] The present invention will be further described in detail below through embodiments, but the protection scope of the present invention is not limited to the scope of the described embodiments.

[0046] Embodiment 1 S1, taking the smelting of 3 t of TC25 titanium alloy (Ti - 6.5Al - 2Mo - 2Zr - 2Sn - 1W) as an example, according to the titanium alloy composition, appropriate amounts of W powder, Mo powder, Zr powder, and Ti powder are taken and added to a ball mill, and a certain amount of absolute ethanol is added. The mass ratio of absolute ethanol to metal powder is 2:1; grinding balls are put in, and the mass ratio of grinding balls to metal powder is 0.5:1. The ball mill tank is closed, and after introducing Ar protective gas, the ball mill is started. The rotation speed of the ball mill is 200 r / min. After ball milling for 2 h, a uniformly mixed slurry of W - Mo - Zr - Ti master alloy is obtained.

[0047] S2, the above-mentioned uniformly mixed slurry of W - Mo - Zr - Ti master alloy is vacuum dried at 100 °C for 1 h to obtain a uniformly mixed powder of W - Mo - Zr - Ti master alloy. The uniformly mixed powder of W - Mo - Zr - Ti master alloy is put into a cylindrical mold with a diameter of 20 mm, and a pressure of 200 MPa is applied to form a compact by die pressing.

[0048] S3, the above-mentioned compact is put into a high-temperature vacuum furnace and heated in the furnace to 1200 °C at a heating rate of 5 °C / min and held for 4 h, and then cooled to room temperature in the furnace to obtain a W - Mo - Zr - Ti master alloy core rod with a diameter of 20 mm. The entire process of heating, holding, and cooling requires maintaining the vacuum degree of the high-temperature furnace to be less than 20 Pa.

[0049] S4, according to the titanium alloy composition, appropriate amounts of other raw materials such as sponge titanium and aluminum beans are taken for batching and mixing, and pressed at a pressure of 30 MPa for 10 s to form a semi-cylindrical electrode block with a semi-circular depression. The diameter of the semi-circular depression is 25 mm, and the outer diameter of the electrode block is 470 mm.

[0050] S5. Stack a number of the above electrode blocks into a cylinder with a central through-hole (the diameter of the central through-hole is 25 mm), insert a W-Mo-Zr-Ti master alloy core rod into the through-hole, and then weld the stacked electrode blocks and the core rod to form a complete consumable electrode.

[0051] S6. Load the prepared consumable electrode into a vacuum consumable arc furnace for the first melting. Before power-on, the vacuum degree is < 2.0 Pa, the leakage rate is < 0.8 Pa / min, the AC arc stabilizing current is 6 A, the AC alternating time is 30 s, the stable melting voltage is 35 V, and the stable melting current is 12 kA.

[0052] S7. Use the ingot obtained from the first melting as the electrode for the second melting. Before power-on, the vacuum degree is < 2.0 Pa, the leakage rate is < 0.8 Pa / min, the AC arc stabilizing current is 10 A, the AC alternating time is 20 s, the stable melting voltage is 35 V, and the stable melting current is 20 kA.

[0053] S8. Use the ingot obtained from the second melting as the electrode for the third melting. Before power-on, the vacuum degree is < 1.0 Pa, the leakage rate is < 0.6 Pa / min, the AC arc stabilizing current is 12 A, the AC alternating time is 20 s, the stable melting voltage is 35 V, and the stable melting current is 25 kA, thus obtaining the TC25 titanium alloy.

[0054] Comparative Example 1 S1. Taking the smelting of 3 t of TC25 titanium alloy (Ti-6.5Al-2Mo-2Zr-2Sn-1W) as an example, according to the components of the titanium alloy, take appropriate amounts of raw materials such as titanium sponge, aluminum beans, W powder, Mo powder, Zr powder, and Ti powder for batching and mixing, and press for 10 s at a pressure of 30 MPa to make semi-cylindrical electrode blocks.

[0055] S2. Stack a number of the above electrode blocks into a cylinder and weld them to form a complete consumable electrode.

[0056] S3. Load the prepared consumable electrode into a vacuum consumable arc furnace for the first melting. Before power-on, the vacuum degree is < 2.0 Pa, the leakage rate is < 0.8 Pa / min, the AC arc stabilizing current is 6 A, the AC alternating time is 30 s, the stable melting voltage is 35 V, and the stable melting current is 12 kA.

[0057] S4. Use the ingot obtained from the first melting as the electrode for the second melting. Before power-on, the vacuum degree is < 2.0 Pa, the leakage rate is < 0.8 Pa / min, the AC arc stabilizing current is 10 A, the AC alternating time is 20 s, the stable melting voltage is 35 V, and the stable melting current is 20 kA.

[0058] S5: Using the ingot obtained from the second melting as the electrode, conduct the third melting. Before power supply, the vacuum degree is <1.0 Pa, the leakage rate is <0.6 Pa / min, the AC arc stabilizing current is 12 A, the AC alternating time is 20 s, the stable melting voltage is 35 V, and the stable melting current is 25 kA, thus obtaining the TC25 titanium alloy.

[0059] Through Example 1 and Comparative Example 1, 3t-grade TC25 titanium alloy ingots were prepared. Figure 4 Perform 12-point sampling analysis on the side of it. The sampling positions are as shown in the figure. After detection, the distribution and composition range of five elements, namely Al, Mo, Zr, Sn, and W, in the ingots obtained from the example and the comparative example are shown in Table 1. The micro-region morphology inside the ingot is as Figure 5 shown.

[0060] Table 1 Alloy element composition and range of the ingots obtained from Example 1 and Comparative Example 1 From the results in Table 1, it can be seen that for the titanium alloy ingot melted in the way of Example 1 (the W-Mo-Zr-Ti intermediate alloy core rod is obtained by batching and mixing W powder, Mo powder, Zr powder and appropriate amount of Ti powder - pressing into shape - vacuum sintering), the composition uniformity is better. The composition range of the W element is only 0.26%, and the composition ranges of the Mo element and the Zr element are also only 0.25% and 0.18% respectively; while for the titanium alloy ingot melted in the way of Comparative Example 1 (W powder, Mo powder, Zr powder are directly mixed and pressed with raw materials such as sponge titanium as the electrode), the composition uniformity is significantly worse. The composition range of the W element is 0.39%, and the composition ranges of the Mo element and the Zr element are also 0.31% and 0.43% respectively.

[0061] From Figure 5 it can be seen that the microstructure of the ingot obtained in the way of Example 1 is uniform and there is no unmelted material; while for the ingot obtained in the way of Comparative Example 1, obvious unmelted W particles are found in the structure. The above results show that in the way of the present invention, by changing the addition method of alloy elements, uniformly mixing refractory elements such as W, Mo, Zr, etc., prefabricating a columnar sintered core rod and inserting it into the center of the sponge titanium consumable electrode, the risk of unmelted intermediate alloy existing in the conventional melting process of titanium alloy containing refractory elements can be effectively eliminated, and the composition uniformity of the ingot can be improved.

Claims

1. A vacuum consumable melting method for a refractory element-containing titanium alloy ingot, characterized in that: It includes the following steps: A. Prepare an intermediate alloy core rod containing refractory elements: According to the titanium alloy composition, take appropriate amounts of refractory element metal powder and Ti powder, mix them evenly through batching - compact them into shape - sinter them in vacuum to obtain the intermediate alloy core rod; the refractory element metal powder is at least one of W powder, Mo powder or Zr powder; B. Prepare a sponge titanium semi - cylindrical electrode block without refractory elements: According to the titanium alloy composition, take appropriate amounts of sponge titanium and the remaining intermediate alloy, mix them evenly through batching, and press them into a semi - cylindrical electrode block with a semi - circular depression; C. Prepare a consumable electrode: Stack several semi - cylindrical electrode blocks with semi - circular depressions into a cylinder with a central through - hole, insert the intermediate alloy core rod into the central through - hole, and then weld the stacked electrode blocks and the core rod to form a complete consumable electrode; the diameter of the central through - hole of the consumable electrode is 20 - 100 mm, the diameter of the intermediate alloy core rod is 2 - 10 mm smaller than the diameter of the central through - hole; the length of the intermediate alloy core rod is the same as that of the consumable electrode; D. Vacuum consumable arc furnace melting: Load the complete consumable electrode into a vacuum consumable arc furnace for 2 - 3 times of melting to obtain a refractory - element - containing titanium alloy ingot with uniform alloy composition distribution.

2. The vacuum consumable melting method according to claim 1, characterized in that: The refractory - element - containing titanium alloy is TA10 - TA12, TA14 - TA15, TA22, TA24, TA30 - TA35, TB2 - TB4, TB7 - TB11, TB15 - TB17, TC6 - TC9, TC11 - TC12, TC16 - TC19, TC21, TC23 - TC24, TC24 or TC27 - TC32.

3. The vacuum consumable melting method according to claim 1, characterized in that: In step A, the specific process of mixing evenly through batching is: Mix the refractory element metal powder and Ti powder with absolute ethanol, put in grinding balls, and carry out ball - milling under the protection of inert gas to obtain the intermediate alloy mixed slurry.

4. The vacuum consumable melting method according to claim 3, characterized in that: In step A, when mixing evenly through batching, at least one of the following is satisfied: The refractory element metal powder is W powder, Mo powder and Zr powder, and the intermediate alloy mixed slurry is W - Mo - Zr - Ti intermediate alloy mixed slurry; The ratio of the mass of absolute ethanol to the total mass of the refractory element metal powder and Ti powder is 1 - 5:1; The ratio of the mass of the grinding balls to the total mass of the refractory element metal powder and Ti powder is 0.5 - 2:1; The rotation speed of the ball - milling is 100 - 200 r / min; The time of the ball - milling is 1 - 5 h.

5. The vacuum consumable melting method according to claim 1, characterized in that: In step A, the specific process of compacting into shape is: After drying the intermediate alloy mixed slurry after mixing evenly through batching, put it into a cylindrical mold, and apply a pressure of 100 - 200 MPa to mold it into shape to obtain a green compact.

6. The vacuum consumable melting method according to claim 1, characterized in that: In step A, the specific process of vacuum sintering is: Under a vacuum degree less than 20 Pa, heat the green compact after compacting into shape in the furnace with a heating rate of 2 - 5 °C / min to 1200 - 1400 °C, then keep it warm for 4 - 6 h, and then cool it to room temperature in the furnace to obtain the intermediate alloy core rod; preferably, the intermediate alloy core rod is a W - Mo - Zr - Ti intermediate alloy core rod.

7. The consumable electrode vacuum arc melting method according to claim 1, characterized in that: In step B, the pressure of the pressing is 25 - 30 MPa, and the pressure holding time is 5 - 10 s.

8. The vacuum consumable melting method according to claim 1, characterized in that: In step D, the parameters for the first melting are as follows: the vacuum degree before power-on is <2.0 Pa, the leakage rate is <0.8 Pa / min, the AC arc stabilizing current is 5 - 7 A, the AC alternating time is 20 - 30 s, the stable melting voltage is 30 - 40 V, and the stable melting current is 10 - 15 kA.

9. The vacuum consumable melting method according to claim 1, characterized in that: In step D, the parameters for the second melting are as follows: the vacuum degree before power-on is <2.0 Pa, the leakage rate is <0.8 Pa / min, the AC arc stabilizing current is 8 - 10 A, the AC alternating time is 10 - 20 s, the stable melting voltage is 30 - 40 V, and the stable melting current is 15 - 25 kA.

10. The vacuum consumable melting method according to claim 1, wherein: In step D, the parameters for the third melting are as follows: the vacuum degree before power-on is <1.0 Pa, the leakage rate is <0.6 Pa / min, the AC arc stabilizing current is 10 - 15 A, the AC alternating time is 10 - 20 s, the stable melting voltage is 30 - 40 V, and the stable melting current is 20 - 30 kA.

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