Vacuum consumable smelting method for TB14 titanium alloy cast ingot smelting

Abstract

The invention discloses a vacuum consumable smelting method for smelting a TB14 titanium alloy cast ingot, which comprises the following steps of: performing vacuum smelting on a prepared electrode for three times to prepare the TB14 titanium alloy cast ingot; wherein the second-time vacuum melting and the third-time vacuum melting are carried out in a step-by-step current reducing mode. According to the method, smelting process parameters are adjusted, smelting is conducted in a step-by-step current reducing mode in the normal smelting stage, stable control over electric arcs during smelting is achieved, too large parameter fluctuation is avoided, and then non-uniform smelting and component deviation are avoided. According to the method, the stability of the ingot casting smelting process and the product quality are effectively improved, and manufacturing of high-quality titanium and refractory alloy is facilitated.

Description

Technical Field

[0001] This invention belongs to the field of high-quality titanium alloy materials technology, and relates to the manufacture of TB14 titanium alloy, specifically to a vacuum consumable melting method for TB14 titanium alloy ingot melting. Background Technology

[0002] TB14 titanium alloy, as a high-strength, high-temperature resistant α+β type titanium alloy, has excellent comprehensive properties, such as high strength, good corrosion resistance and suitable thermal stability. It is widely used in key components such as compressor blades of aerospace engines and rocket fuel tanks.

[0003] However, TB14 titanium alloy faces the following challenges during vacuum arc remelting: the melting point of Nb in TB14 titanium alloy is as high as 2469℃, and its density is 8.57 g / cm³. 3 Ti has a melting point of 1670℃ and a density of 4.50 g / cm³. 3 Due to the significant differences in their physical properties, controlling the stability of the electric arc during the smelting process is quite difficult, resulting in large fluctuations in smelting voltage and current, and uneven electrode melting rates, leading to compositional deviations in different parts of the ingot. During the smelting process, Nb, as a high-density element, has a strong tendency to sink in the molten pool, easily causing macroscopic segregation of the ingot composition. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a vacuum consumable melting method for TB14 titanium alloy ingots, solving the technical problems in existing technologies where the physical properties of Nb and Ti components of TB14 titanium alloy differ greatly, making it difficult to control arc stability during melting, and parameter fluctuations lead to uneven melting and compositional deviations; high-density Nb tends to sink, causing macroscopic segregation in the ingot.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A vacuum consumable melting method for smelting TB14 titanium alloy ingots includes: performing three vacuum melting processes on prepared electrodes to obtain TB14 titanium alloy ingots; wherein the second and third vacuum melting processes are both performed using a step-by-step current reduction method. The method specifically includes the following steps: Step 1, Electrode preparation: The raw materials of TB14 titanium alloy, excluding the niobium rod, are mixed and prepared according to the composition ratio, pressed into multiple electrode blocks, and then welded together with the niobium rod; during welding, the electrode blocks are distributed around the niobium rod.

[0006] Step 2, first vacuum melting: Increase the melting current to 9.5-13.5KA, the melting voltage to 32-38V, and the arc-stabilizing DC current to 10-15A, preferably 10A.

[0007] Step 3, Second Vacuum Melting: Increase the melting current to 18-22 kA and the melting voltage to 31-37 V, maintain for 40-70 min, then reduce the melting current to 11-15 kA and the melting voltage to 30.5-36.6 V, with a stabilizing DC current of 5-10 A, preferably 8 A.

[0008] Step 4, Third Vacuum Melting: Increase the melting current to 16.5–20.5 kA and the melting voltage to 30–36 V. Then gradually decrease the current to 14–18 kA, 10–14 kA, 6–10 kA, and 2–6 kA. The corresponding melting voltages are 30–36 V, 29.1–35.1 V, 27–33 V, and 24–30 V, respectively. The arc-stabilizing AC current is 7–10 A, preferably 8 A, and the arc-stabilizing half-cycle is 10–30 S, preferably 20 S.

[0009] The present invention also has the following technical features: Specifically, in step one, the welding method is manual plasma welding; the welding current is 250–450A, the argon gas flow rate of the welding torch is 10–20L / min, the argon gas flow rate of the protective shield is 20–30L / min; the pressing pressure is ≥2500T, and the electrode block density is ≥3.5g / cm³. 3 .

[0010] Specifically, in step one, the raw materials for TB14 titanium alloy include sponge titanium, titanium dioxide, and niobium rods; after welding, the length of the niobium rods extends 0-20 mm beyond the sponge titanium.

[0011] Specifically, in steps two through four, a base pad is placed at the bottom of the crucible each time vacuum melting is performed.

[0012] The beneficial technical effects of this invention compared to the prior art are as follows: (I) This invention adjusts the smelting process parameters. During the normal smelting stage, a gradual reduction in current is adopted, achieving stable control of the electric arc during smelting and avoiding excessive parameter fluctuations, thereby preventing uneven melting and compositional deviations. This invention effectively improves the stability of the ingot smelting process and product quality, contributing to the manufacture of high-quality titanium and refractory alloys.

[0013] (II) The present invention adds a base pad of the same grade before the first, second and third melting. This method can effectively alleviate the phenomenon that the molten pool solidifies too quickly due to the crucible temperature being too low during the early melting. While rapidly increasing the current, it can also avoid breaking through the crucible and ensure the stability of the ingot production process.

[0014] (III) The present invention adopts a novel assembly method, which combines sponge titanium and niobium rods; a special mold is used to press the electrode block, and during welding, it is distributed around the niobium rod, forming an overall wrapped shape; this method not only reduces the production cost of TB14 electrode preparation, but also effectively improves the composition uniformity of one melting. Attached Figure Description

[0015] Figure 1 The welding method for TB14 electrode blocks and niobium rods. Figure 1 In the middle: the gray cuboid represents the sponge titanium electrode block; the dark cylinder in the center represents the niobium rod; and the green dots represent the solder joints.

[0016] Figure 2 This is a multi-point sampling diagram of TB14 titanium alloy ingot.

[0017] The technical solution of the present invention will be further described below with reference to the embodiments. Detailed Implementation

[0018] It should be noted that all raw materials used in this invention, unless otherwise specified, are those known in the art. For example, the specific composition of TB14 titanium alloy is: 45 wt% niobium, 0.08 wt% oxygen, and the balance being titanium.

[0019] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0020] Example 1: This embodiment provides a vacuum consumable melting method for smelting TB14 titanium alloy ingots, which specifically includes the following steps: Step 1, Electrode Preparation: Using grade 0 / 0A titanium sponge, titanium dioxide, and niobium rods as raw materials, the required niobium rods must have an Nb content ≥99.9%. The titanium sponge and titanium dioxide are mixed according to the composition ratio of TB14 titanium alloy. After the mixture is complete, a special mold is used to press the electrode block, with a pressing pressure ≥2500T and an electrode block density ≥3.5g / cm³. 3 Finally, manual plasma welding was used with a welding current of 350A, an argon gas flow rate of 15L / min for the welding torch, and an argon gas flow rate of 25L / min for the protective shield, to weld the electrode block to the niobium rod together. Figure 1 As shown, the electrode blocks are evenly distributed around the niobium rod, forming a wrapping shape, and two TB14 electrodes are obtained in this manner. After welding, the length of the niobium rod should be 0-20 mm higher than the sponge titanium. In this embodiment, the composition ratio of the TB14 titanium alloy raw material is: 45 wt% niobium, 0.08 wt% oxygen, and the balance is titanium.

[0021] Step 2, First Vacuum Melting: Before the first melting, prepare a base pad of the same grade and place it at the bottom of the crucible. Record its weight and thickness. Melt according to the first melting process requirements. After melting, flatten the ends of both primary ingots and saw off the raw material at the bottom. Machine-machine an anti-overflow groove at the bottom of one primary ingot. The parameters for the first melting are: melting current 9.5~13.5KA, melting voltage 32~38V, and arc stabilization current 10A (DC).

[0022] Step 3, Second Vacuum Melting: For the second melting, the bottom slice of the primary ingot is placed as a base at the bottom of the crucible, and its weight and thickness are recorded. Melting is carried out according to the requirements of the second melting process. After melting, the bottom of the secondary ingot is sawn with a flat end, and an anti-overflow groove is machined at the bottom. The second melting parameters are implemented by gradually decreasing the current. After arc ignition, the melting current is increased to 18-22 kA, the melting voltage is 31-37 V, and after maintaining this for 50 minutes, the melting current is reduced to 11-15 kA, the melting voltage is 30.5-36.6 V, and the arc stabilization current is 8 A (DC).

[0023] Step 4, Third Vacuum Melting: Before the third melting, place the bottom slice of the secondary ingot as a base at the bottom of the crucible and record its weight and thickness. Melt according to the requirements of the third melting process. After melting, peel and saw the ingot. The parameters for the third melting are implemented by gradually decreasing the current. After arc ignition, the melting current is increased to 16.5-20.5 kA, and the melting voltage is 30-36 V. The current is gradually decreased to 14-18 kA, 10-14 kA, 6-10 kA, and 2-6 kA, corresponding to melting voltages of 30-36 V, 29.1-35.1 V, 27-33 V, and 24-30 V, respectively. The arc stabilization current is 8 A (AC), and the arc stabilization period is 20 seconds (half a cycle).

[0024] Comparative Example 1: This comparative example presents a vacuum consumable melting method for smelting TB14 titanium alloy ingots. The method specifically includes the following steps: Step 1, Electrode Preparation: In this comparative example, Step 1 is exactly the same as Step 1 in Example 1.

[0025] Step 2, First Vacuum Melting: Melting is carried out according to the requirements of the first melting process. After melting, both primary ingots are flattened, and the raw material is sawn off at the bottom. An anti-overflow groove is machined into the bottom of one of the primary ingots. The parameters for the first melting are: melting current 9.5KA, melting voltage 33~36V, and arc stabilization current 8~10A (DC).

[0026] Step 3, Second Vacuum Melting: Melting is carried out according to the requirements of the second melting process. After melting, the second ingot is flattened and the bottom is sawn, and an anti-overflow groove is machined at the bottom. The parameters for the second melting are as follows: melting current 13-16KA, melting voltage 33-36V, arc stabilization current 10-13A (AC), and arc stabilization period 10S (half a cycle).

[0027] Step 4, Third Vacuum Melting: Melting is carried out according to the requirements of the three-stage melting process. After melting, the outer skin is peeled and sawn. The parameters for the three-stage melting are as follows: melting current 16.5~20.5KA, melting voltage 32~36V, arc stabilization current 10~18A (AC), arc stabilization period 5S (half-cycle).

[0028] Comparative Example 2: This comparative example presents a vacuum consumable melting method for smelting TB14 titanium alloy ingots. The method specifically includes the following steps: Step 1, Electrode Preparation: In this comparative example, Step 1 is exactly the same as Step 1 in Example 1.

[0029] Step 2, First Vacuum Melting: Prepare a base pad of the same grade and place it at the bottom of the crucible. Record its weight and thickness. Melt according to the first-stage melting process requirements. After melting, flatten the ends of both primary ingots and saw off the raw material at the bottom. Machine-machine an anti-overflow groove at the bottom of one primary ingot. The primary melting parameters are: melting current 9.5~13.5KA, melting voltage 32~38V, and arc stabilization current 10A (DC).

[0030] Step 3, Second Vacuum Melting: Place the bottom slice of the primary ingot as a base at the bottom of the crucible and record its weight and thickness. Melt according to the secondary melting process requirements. After melting, flatten the secondary ingot and machine an anti-overflow groove at the bottom. The secondary melting parameters are implemented by gradually decreasing the current. After arc ignition, the melting current is increased to 13-16 kA, the melting voltage is 31-37 V, and maintained for 80 minutes. Then, the melting current is reduced to 11-15 kA, the melting voltage is 30.5-36.6 V, the arc stabilization current is 8 A (AC), and the arc stabilization period is 10 seconds (half a cycle).

[0031] Step 4, Third Vacuum Melting: Prepare a base pad of the same grade, place it at the bottom of the crucible, and record its weight and thickness. Melt according to the requirements of the third melting process. After melting, peel and saw off the outer layer. The second melting parameters adopt a step-by-step current reduction method. After arc initiation, the melting current is increased to 16.5-20.5KA, and the melting voltage is 30-36V. In the later stages, the current is gradually reduced to 14-18KA, 10-14KA, 6-10KA, and 2-6KA, corresponding to melting voltages of 30-36V, 29.1-35.1V, 27-33V, and 24-30V. The arc stabilization current is 6A (AC), and the arc stabilization period is 20S (half a cycle).

[0032] Effect verification: After smelting, the composition of the ingot was summarized, and the results are shown in Tables 1 and 2. It can be seen that the TB14 titanium alloy ingot prepared using the method described in this invention has a more stable chemical composition.

[0033] Table 1. Composition test results of the sidewall of TB14 titanium alloy ingot

[0034] Table 2. Multi-point composition test results of TB14 titanium alloy ingot

[0035] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A vacuum consumable melting method for smelting TB14 titanium alloy ingots, characterized in that, After the prepared electrode was subjected to three vacuum melting processes, TB14 titanium alloy ingots were obtained; the second and third vacuum melting processes were carried out by gradually decreasing the current. The parameters for the second vacuum melting include: increasing the melting current to 18-22 kA, the melting voltage to 31-37 V, maintaining this for 40-70 minutes, then reducing the melting current to 11-15 kA, the melting voltage to 30.5-36.6 V, and the arc-stabilizing DC current to 5-10 A. The parameters for the third vacuum melting process include: increasing the melting current to 16.5–20.5 kA and the melting voltage to 30–36 V, then gradually decreasing the current to 14–18 kA, 10–14 kA, 6–10 kA, and 2–6 kA, with corresponding melting voltages of 30–36 V, 29.1–35.1 V, 27–33 V, and 24–30 V, respectively. The arc-stabilizing AC current is 7–10 A, and the arc-stabilizing half-cycle is 10–30 S.

2. The vacuum consumable melting method for smelting TB14 titanium alloy ingots as described in claim 1, characterized in that, The parameters for the first vacuum melting include: melting current of 9.5–13.5 kA, melting voltage of 32–38 V, and arc-stabilizing DC current of 10–15 A.

3. The vacuum consumable melting method for smelting TB14 titanium alloy ingots as described in claim 1, characterized in that, The electrode preparation process includes: mixing and blending TB14 titanium alloy raw materials (excluding niobium rods) according to the component ratio, pressing them into multiple electrode blocks, and then welding them together with niobium rods; during welding, the electrode blocks are distributed around the niobium rods.

4. The vacuum arc remelting method for smelting TB14 titanium alloy ingots as described in claim 3, characterized in that, The welding method is manual plasma welding.

5. The vacuum consumable melting method for smelting TB14 titanium alloy ingots as described in claim 3, characterized in that, The welding current is 250-450A, the argon flow rate of the welding torch is 10-20L / min, and the argon flow rate of the protective cover is 20-30L / min.

6. The vacuum consumable melting method for smelting TB14 titanium alloy ingots as described in claim 3, characterized in that, Compression pressure ≥2500T.

7. The vacuum consumable melting method for smelting TB14 titanium alloy ingots as described in claim 3, characterized in that, Electrode block density ≥ 3.5 g / cm³ 3 .

8. The vacuum consumable melting method for smelting TB14 titanium alloy ingots as described in claim 3, characterized in that, The raw materials for TB14 titanium alloy include sponge titanium, titanium dioxide, and niobium rods.

9. The vacuum arc remelting method for smelting TB14 titanium alloy ingots as described in claim 7, characterized in that, After welding, the length of the niobium rod extends 0-20 mm beyond the sponge titanium.

10. The vacuum consumable melting method for smelting TB14 titanium alloy ingots as described in claim 1, characterized in that, Place a base pad at the bottom of the crucible during each vacuum melting process.

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