Method for eliminating arc striking of crucible wall in titanium alloy VAR smelting process and application

Abstract

The invention belongs to the field of aeronautical material manufacturing, and relates to a method for eliminating arc striking of a crucible wall in the titanium alloy VAR smelting process and application. According to the method, the arc striking phenomenon of the crucible wall in the VAR smelting process of the high-Cl-content titanium sponge is completely eliminated by preventing the high-Cl-content titanium sponge, the consumable electrode and the electrode block from absorbing moisture and adopting multi-row fast extraction degassing and short-arc smelting in the VAR smelting process; specifically, through electrode block structure optimization and technological parameter cooperation, closed-loop control is formed from multiple dimensions of gas generation, gas discharge, arc stability and the like, and the limitation that a traditional method only depends on a single technology is solved; furthermore, moisture absorption prevention control reduces moisture introduction from the source, low forevacuum control strengthens gas discharge in the smelting process, and double control greatly reduces the splashing risk; furthermore, differentiated parameters are formulated for key areas such as welding seams, and the process stability is ensured through quantitative control.

Description

Technical Field

[0001] This invention belongs to the field of aerospace materials manufacturing, and relates to titanium alloys, specifically to a method and application for eliminating arcing on the crucible wall during the VAR melting process of titanium alloys. Background Technology

[0002] VAR melting, a core process in titanium alloy ingot preparation, requires first preparing the desired sponge titanium and other alloying materials into consumable electrode blocks. These blocks are then welded together in a vacuum plasma welding box to form consumable electrodes. In a VAR furnace, the high temperature generated by the arc discharge between the electrodes and the crucible serves as the heat source, melting the electrodes to form titanium and titanium alloy ingots. The stability of VAR melting directly determines the metallurgical quality and production safety of the ingots. Due to the special nature of sponge titanium production, chloride (Cl) is an essential byproduct element in the raw materials. When the Cl⁻ content in sponge titanium exceeds 0.06 wt.%, it easily absorbs moisture to form hydrogen-chlorine complexes such as TiClx・nH₂O. At high melting temperatures (>1668℃), these complexes undergo a violent decomposition reaction: TiClx・nH₂O → TiClx↑ + nH₂O↑, instantly releasing a large amount of gas and causing explosive splashing on the surface of the molten pool.

[0003] The molten titanium droplets generated by the splashing alter the electric field distribution between the consumable electrode and the water-cooled copper crucible, triggering an abnormal electric arc (arc striking) between the electrode and the crucible wall. Figure 6 and Figure 7 As shown. Research indicates that the energy of a single arc strike can reach 10. 4 ~10 5 J is sufficient to penetrate a 10-20mm thick copper crucible wall (copper's melting point is 1083℃), posing a risk of explosion when cooling water comes into contact with the molten pool. Industry statistics show that the crucible penetration rate during high-Cl sponge titanium smelting is as high as 3-5%, severely restricting production efficiency and safety. In response, existing patented technologies rarely report methods for preventing VAR (Vacuum-Acid Reduction) smelting processes.

[0004] In view of this, the present invention provides a method for eliminating arcing on the crucible wall during the VAR melting process of titanium alloys, so as to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and application for eliminating arcing on the crucible wall during the VAR melting process of titanium alloys.

[0006] To achieve the above objectives, the present invention provides the following technical solution: On the one hand, the present invention provides a method for eliminating the arcing of the crucible wall during the VAR melting process of titanium alloys. This method is achieved by preventing moisture absorption of high-Cl content sponge titanium, consumable electrodes and electrode blocks, and by using multi-row fast degassing and short-arc melting during the VAR melting process, so as to completely eliminate the arcing phenomenon of the crucible wall during the VAR melting process of high-Cl sponge titanium.

[0007] On the other hand, the present invention provides a method for eliminating arcing on the crucible wall during the VAR melting process of titanium alloys, comprising the following steps: Step 1: Strict moisture-proof treatment is applied to high-Cl content sponge titanium, electrode blocks with dedicated exhaust channels prepared from high-Cl content sponge titanium and intermediate alloys, and consumable electrodes. Step 2: Place the consumable electrode in a matching crucible and adjust its position relative to the crucible. Then, load it into a vacuum consumable arc furnace and evacuate it to the pre-vacuum level and leakage rate. Step 3: Use a stepped, long-term preheating method to initiate and preheat the consumable electrode; Step 4: The preheated consumable electrode is melted using a short-arc melting process. When the melting reaches the vicinity of the weld, a low-voltage weld transition is used to complete the melting at the weld.

[0008] Specifically, in step 1, the moisture-proof treatment is as follows: the high Cl content sponge titanium is stored in a dry, inert gas-sealed protective container with a dew point ≤ -40℃ and a purity ≥ 99.999%, and the storage period after opening is strictly controlled within 72 hours; the prepared consumable electrode and electrode block are placed in an environment with a temperature of 50~90℃ and a relative humidity ≤ 40%, and the placement period is ≤ 48 hours; the high Cl content sponge titanium and electrode block that have not been used within the production period need to be vacuum dried again, with a vacuum degree ≤ 1Pa, a drying temperature of 115~125℃, and a heat preservation time ≥ 4 hours.

[0009] Specifically, in step 1, the electrode block with the dedicated exhaust channel structure is as follows: n radial exhaust channels of diameter D are arranged vertically and evenly distributed along the combined electrode block, with the center spacing of each exhaust channel being L1, and 40mm≤L1≤L / 2, where n≥1, and L is the longitudinal length of each electrode block; m longitudinal exhaust channels of diameter D are arranged radially along the electrode block, with the center spacing of adjacent exhaust channels being W1, and 40mm≤W1≤W / 2, where m≥1, and W is the width of the electrode block; D and the outer circle diameter Φ of the electrode block satisfy: D=(0.05-0.10)Φ, and D≥15mm; the radial exhaust channels and the axial exhaust channels are interconnected to form a three-dimensional exhaust network.

[0010] Specifically, in step 2, the diameter Φ of the consumable electrode and the diameter φ of the crucible satisfy Φ=(0.7-0.9)φ. The adjustment of the position of the consumable electrode relative to the crucible is specifically as follows: the distance deviation between the consumable electrode and four points evenly distributed along the circumference of the crucible is ≤10mm.

[0011] Specifically, in step 2, the pre-vacuum degree is ≤1 Pa and the leakage rate is ≤0.8 Pa / min.

[0012] Specifically, in step 3, the stepped long-term preheating arc-starting process is as follows: First stage: Arc ignition current range 3~5kA, and holding time 6~10min. This stage is the initial heating stage of the consumable electrode. The vacuum control in the furnace is ≤1Pa. Second stage: The current is increased to 5~6.5kA within 0.5~2min and maintained at this current for 8~15min. During this stage, the consumable electrode is preheated and then the exhaust begins. The vacuum degree in the furnace should be controlled at 1~5Pa. The third stage: the current is increased to 7-9kA within 0.5-2min and maintained at this current for 15-30min. During this stage, the consumable electrode is vented at high temperature without melting, and the vacuum degree in the furnace is controlled at 1-5Pa. Fourth stage: The current is directly increased to the melting current set by the process in 2~30 minutes. At this time, the normal melting state of the consumable electrode is entered. During this stage, the vacuum degree in the furnace is maintained at ≤10Pa throughout the process, and there is no need to start the booster pump.

[0013] Specifically, in step 4, the low-voltage weld transition is as follows: when melting to the weld position of the consumable electrode, the voltage at the weld is reduced to 70-80% of the rated voltage, and the duration is 1.2-1.5 times the melting time of the weld area, so as to avoid the arc deviation phenomenon caused by the sudden change in the structure at the weld when the voltage rises.

[0014] Specifically, in step 4, the short-arc melting process is as follows: the initial arc length is controlled at 5~30mm when the arc is started; during the melting process, the arc length must be controlled within (0.01~0.07)φ and within 5~40mm to reduce the influence of gas disturbance on the electric arc, where φ is the diameter of the crucible.

[0015] In another aspect, the present invention provides an application of the method described above for eliminating crucible wall arcing during the VAR melting process of titanium alloys in the preparation of large-diameter high-performance titanium alloy ingots for aerospace applications.

[0016] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: This invention completely eliminates the arcing phenomenon on the crucible wall during the VAR melting process of high-Cl sponge titanium by preventing moisture absorption from high-Cl content sponge titanium, consumable electrodes, and electrode blocks, and by employing multi-row rapid degassing and short-arc melting during the VAR melting process. Specifically, through electrode block structure optimization and process parameter coordination, a closed-loop control is formed from multiple dimensions such as gas generation, exhaust, and arc stability, overcoming the limitations of traditional methods that rely on only a single process. Furthermore, moisture absorption prevention control reduces moisture introduction at the source, while low pre-vacuum control enhances gas exhaust during the melting process, and the dual control significantly reduces the risk of spatter. In addition, differentiated parameters are formulated for key areas such as welds, and process stability is ensured through quantitative control (such as electrode diameter and crucible diameter control, electrode and crucible concentricity control, etc.). This invention achieves stability in the VAR melting process and completely eliminates the safety hazard of crucible breakdown.

[0017] The method of this invention is applicable to the VAR melting of titanium alloys with various high Cl content sponge titanium, and has important application value, especially for the safe production of large-diameter high-performance titanium alloy ingots for aerospace applications. Attached Figure Description

[0018] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The flowchart provided by this invention; Figure 2 This is a front view of the electrode block with a dedicated exhaust channel according to the present invention; Figure 3 for Figure 2 Top view; Figure 4 for Figure 3 Sectional view along axis AA; Figure 5 This is a photograph of the electrode block with a dedicated exhaust channel according to the present invention. Figure 6 A photograph of the VAR electrode block arcing phenomenon inside the crucible under traditional processes; Figure 7 Photograph of the inner wall of the crucible after VAR melting using traditional methods; Figure 8 This is a photograph of the molten pool during the smelting process in Example 1 of the present invention; Figure 9 This is a photograph of the crucible surface in Example 1 of the present invention; Figure 10 This is a photograph of the molten pool during the smelting process in Example 2 of the present invention; Figure 11 This is a photograph of the crucible surface in Example 2 of the present invention; Figure 12 This is a photograph of the molten pool state during the smelting process in Example 3 of the present invention; Figure 13 This is a photograph of the crucible surface in Example 3 of the present invention. Detailed Implementation

[0021] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0022] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0023] On the one hand, the present invention provides a method for eliminating the arcing of the crucible wall during the VAR melting process of titanium alloys. This method is achieved by preventing moisture absorption of high-Cl content sponge titanium, consumable electrodes and electrode blocks, and by using multi-row fast degassing and short-arc melting during the VAR melting process, so as to completely eliminate the arcing phenomenon of the crucible wall during the VAR melting process of high-Cl sponge titanium.

[0024] On the other hand, the present invention provides a method for eliminating arcing on the crucible wall during the VAR melting process of titanium alloys, comprising the following steps: Step 1: Strict moisture-proof treatment is applied to high-Cl content sponge titanium, electrode blocks with dedicated exhaust channels prepared from high-Cl content sponge titanium and intermediate alloys, and consumable electrodes. Step 2: Place the consumable electrode in a matching crucible and adjust its position relative to the crucible. Then, load it into a vacuum consumable arc furnace and evacuate it to the pre-vacuum level and leakage rate. Step 3: Use a stepped, long-term preheating method to initiate and preheat the consumable electrode; Step 4: The preheated consumable electrode is melted using a short-arc melting process. When the melting reaches the vicinity of the weld, a low-voltage weld transition is used to complete the melting at the weld.

[0025] Specifically, in step 1, the moisture-proof treatment is as follows: the high Cl content sponge titanium is stored in a dry, inert gas-sealed protective container with a dew point ≤ -40℃ and a purity ≥ 99.999%, and the storage period after opening is strictly controlled within 72 hours; the prepared consumable electrode and electrode block are placed in an environment with a temperature of 50~90℃ and a relative humidity ≤ 40%, and the placement period is ≤ 48 hours; the high Cl content sponge titanium and electrode block that have not been used within the production period need to be vacuum dried again, with a vacuum degree ≤ 1Pa, a drying temperature of 115~125℃, and a heat preservation time ≥ 4 hours.

[0026] Specifically, in step 1, the electrode block with the dedicated exhaust channel structure is as follows: n radial exhaust channels of diameter D are arranged longitudinally and evenly distributed perpendicular to the longitudinal direction on the assembled electrode block. The center-to-center distance of each exhaust channel is L1, and 40mm≤L1≤L / 2, where n≥1 and L is the longitudinal length of each electrode block; m longitudinal exhaust channels of diameter D are arranged radially and evenly distributed along the electrode block. The center-to-center distance of adjacent exhaust channels is W1, and 40mm≤W1≤W / 2, where m≥1 and W is the width of the electrode block; the diameter of the axial exhaust channel is D, and D satisfies the following condition with respect to the outer circle diameter Φ of the electrode block: D=(0.05-0.10)Φ, and D≥15mm; the radial exhaust channels and the axial exhaust channels are interconnected to form a three-dimensional exhaust network.

[0027] Specifically, in step 2, the diameter Φ of the consumable electrode and the diameter φ of the crucible satisfy Φ=(0.7-0.9)φ. The adjustment of the position of the consumable electrode relative to the crucible is specifically as follows: the distance deviation between the consumable electrode and four points evenly distributed along the circumference of the crucible is ≤10mm.

[0028] Specifically, in step 2, the pre-vacuum degree is ≤1 Pa and the leakage rate is ≤0.8 Pa / min.

[0029] Specifically, in step 3, the stepped long-term preheating arc-starting process is as follows: First stage: Arc ignition current range 3~5kA, and holding time 6~10min. This stage is the initial heating stage of the consumable electrode. The vacuum control in the furnace is ≤1Pa. Second stage: The current is increased to 5~6.5kA within 0.5~2min and maintained at this current for 8~15min. During this stage, the consumable electrode is preheated and then the exhaust begins. The vacuum degree in the furnace should be controlled at 1~5Pa. The third stage: the current is increased to 7-9kA within 0.5-2min and maintained at this current for 15-30min. During this stage, the consumable electrode is vented at high temperature without melting, and the vacuum degree in the furnace is controlled at 1-5Pa. Fourth stage: The current is directly increased to the melting current set by the process in 2~30 minutes. At this time, the normal melting state of the consumable electrode is entered. During this stage, the vacuum degree in the furnace is maintained at ≤10Pa throughout the process, and there is no need to start the booster pump.

[0030] Specifically, in step 4, the low-voltage weld transition is as follows: when melting to the weld position of the consumable electrode, the voltage at the weld is reduced to 70-80% of the rated voltage, and the duration is 1.2-1.5 times the melting time of the weld area, so as to avoid the arc deviation phenomenon caused by the sudden change in the structure at the weld when the voltage rises.

[0031] Specifically, in step 4, the short-arc melting process is as follows: the initial arc length is controlled at 5~30mm when the arc is started; during the melting process, the arc length must be controlled within (0.01~0.07)φ and within 5~40mm to reduce the influence of gas disturbance on the electric arc, where φ is the diameter of the crucible.

[0032] To demonstrate the effectiveness of the present invention, the following embodiments are provided for verification.

[0033] Example 1 See Figure 1 As shown, this example provides a method for eliminating arcing on the crucible wall during the VAR melting process of TC4 titanium alloy with a diameter of Ф440mm. The method specifically includes the following steps: Step 1: Store high-Cl content (0.065wt%) sponge titanium in an inert gas-sealed protective container with a dew point ≤ -40℃ and a purity ≥ 99.999%. Place the prepared consumable electrode and electrode block with a dedicated exhaust channel structure in a clean storage room at 50℃ and 40% relative humidity. After unpacking, the sponge titanium is prepared for 72 hours, and the consumable electrode block is prepared for 48 hours. The electrode block is prepared by mixing high-Cl content (0.065wt.%) sponge titanium with an intermediate alloy at a TC4 ratio and then preparing it with a dedicated exhaust channel structure using an 80MN hydraulic press. Specifically, a radial exhaust channel with a diameter D of 30mm is set longitudinally on the electrode block, with the center of each exhaust channel 200mm from the longitudinal side of the electrode block. Two axial exhaust channels are set transversely along the electrode block, with the center of each axial exhaust channel W1 = 140mm from the radial center of the electrode block and a diameter D = 30mm. Figures 2-5 As shown.

[0034] Step 2: Load the consumable electrode into the furnace, where the electrode diameter Φ and the crucible diameter φ satisfy Φ=0.8φ, and the distance difference between the four symmetrical points of the crucible and the consumable electrode is 10mm; after loading the furnace, evacuate the furnace, with an actual vacuum degree of 1Pa and a leakage rate ≤0.7Pa / min.

[0035] Step 3: Stepped long-term preheating arc ignition. In the first stage, the low current of 3kA is used to ignite the arc and is maintained for 6 minutes to preheat the electrode, with the vacuum inside the furnace controlled at 1Pa. In the second stage, the current is increased from 3kA to 5kA in 2 minutes and maintained for 8 minutes, with the vacuum inside the furnace controlled at 1~5Pa. In the third stage, the current is increased from 5kA to 6.5kA in 2 minutes and maintained for 15 minutes, with the vacuum inside the furnace controlled at 1~5Pa. In the fourth stage, the current is directly increased to the melting current set by the process in 5 minutes. During the normal melting period, the booster pump is turned off, and the vacuum inside the furnace is maintained at ≤10Pa.

[0036] Step 4: Short-circuit melting control. The initial arc length is controlled at 30mm when the arc is started. During the melting process, the arc length must be controlled at 31mm (i.e., 0.07φ). Observe the state of the molten pool during the melting process and check the surface of the crucible after it is taken out of the furnace. When melting to the vicinity of the weld, the melting voltage is reduced to 80% of the set value and the melting time in the weld area is continued for 1.5 times. The transition at the weld is smooth.

[0037] Depend on Figure 8 It can be seen that the molten pool is stable and there is no splashing during the smelting process; from Figure 9 It can be seen that the surface of the crucible is flat after it is taken out of the furnace, and there is no arcing phenomenon on the crucible wall.

[0038] Example 2 See Figure 1 As shown, this example provides a method for eliminating arcing on the crucible wall during the VAR melting process of Ф560mm TA15 titanium alloy, specifically including the following steps: Step 1: Store high-Cl content (0.07wt%) sponge titanium in an inert gas-sealed protective container with a dew point ≤ -40℃ and a purity ≥ 99.999%. Place the prepared consumable electrode and electrode block with a dedicated exhaust channel structure in a clean storage room at 50℃ and 40% relative humidity. After unpacking, the sponge titanium is prepared for 48 hours, and the consumable electrode block is prepared for 24 hours. The electrode block is prepared by mixing high-Cl content (0.07wt.%) sponge titanium with an intermediate alloy at a TA15 ratio and then preparing it with a dedicated exhaust channel structure using an 80MN hydraulic press. Specifically, a radial exhaust channel with a diameter D of 30mm is set longitudinally on the electrode block, with the center of each exhaust channel 200mm from the longitudinal side of the electrode block. Two axial exhaust channels are set transversely along the electrode block, with the center of each axial exhaust channel W1 = 140mm from the radial center of the electrode block and a diameter D = 30mm. Figures 2-5 As shown.

[0039] Step 2: Load the consumable electrode into the furnace, where the electrode diameter Φ and the crucible diameter φ satisfy Φ=0.86φ, and the distance difference between the four symmetrical points of the crucible and the consumable electrode is 10mm; after loading the furnace, evacuate the furnace, with an actual vacuum degree of 0.8Pa and a leakage rate ≤0.65Pa / min.

[0040] Step 3: Stepped long-term preheating arc ignition. In the first stage, the low current of 4kA is used to ignite the arc and is maintained for 8 minutes to preheat the electrode, with the vacuum inside the furnace controlled at 1Pa. In the second stage, the current is increased from 4kA to 5.5kA in 1 minute and maintained for 12 minutes, with the vacuum inside the furnace controlled at 1~5Pa. In the third stage, the current is increased from 5.5kA to 8kA in 2 minutes and maintained for 25 minutes, with the vacuum inside the furnace controlled at 1~5Pa. In the fourth stage, the current is directly increased to the melting current set by the process in 20 minutes. During the normal melting period, the booster pump is turned off, and the vacuum inside the furnace is maintained at ≤10Pa.

[0041] Step 4: Short-circuit melting control. When starting the arc, the initial arc length should be controlled at 10mm. During the melting process, the arc length must be controlled at 22mm (i.e., 0.04φ). Observe the state of the molten pool during the melting process and check the surface of the crucible after it is taken out of the furnace. When melting to the vicinity of the weld, the melting voltage should be reduced to 70% of the set value and the melting time in the weld area should be 1.3 times the time. The transition at the weld should be smooth.

[0042] Depend on Figure 10 It can be seen that the molten pool is stable and there is no splashing during the smelting process; from Figure 11 It can be seen that the surface of the crucible is flat after it is taken out of the furnace, and there is no arcing phenomenon on the crucible wall.

[0043] Example 3 See Figure 1 This example provides a method for eliminating arcing on the crucible wall during the VAR melting process of 640mm TC11 titanium alloy, specifically including the following steps: Step 1: High Cl content (0.08wt%) sponge titanium is stored in an inert gas-sealed protective container with a dew point ≤ -40℃ and a purity ≥ 99.999%. The prepared consumable electrode and electrode block with a dedicated exhaust channel structure are placed in a clean storage room with a temperature of 70℃ and a relative humidity of 40%. After unpacking, the sponge titanium is kept in production for 64 hours, and the consumable electrode block is kept in production for 36 hours. The electrode block is prepared by mixing high Cl content (0.08wt.%) sponge titanium with an intermediate alloy in a TC11 ratio and then preparing it into an electrode block with a dedicated exhaust channel structure using an 80MN hydraulic press. Specifically, a radial exhaust channel with a diameter D of 30mm is set longitudinally on the electrode block, with the center of each exhaust channel 200mm from the longitudinal side of the electrode block. Two axial exhaust channels are set transversely along the electrode block, with the center of each axial exhaust channel 140mm from the radial center of the electrode block and a diameter D of 30mm. Figures 2-5 As shown.

[0044] Step 2: Load the consumable electrode into the furnace, where the electrode diameter Φ and the crucible diameter φ satisfy Φ=0.81φ, and the distance difference between the four symmetrical points of the crucible and the consumable electrode is 10mm; after loading the furnace, evacuate the furnace, with an actual vacuum degree of 0.9Pa and a leakage rate ≤0.65Pa / min.

[0045] Step 3: Stepped long-term preheating arc ignition. In the first stage, the low current of 5kA is used to ignite the arc and maintain it for 10 minutes to preheat the electrode, with the vacuum inside the furnace controlled at 1Pa. In the second stage, the current is increased from 5kA to 6.5kA in 1.5 minutes and maintained for 12 minutes, with the vacuum inside the furnace controlled at 1~5Pa. In the third stage, the current is increased from 6.5kA to 9kA in 2 minutes and maintained for 30 minutes, with the vacuum inside the furnace controlled at 1~5Pa. In the fourth stage, the current is directly increased to the melting current set by the process in 30 minutes. During the normal melting period, the booster pump is turned off, and the vacuum inside the furnace is maintained at ≤10Pa.

[0046] Step 4: Short-circuit melting control. When starting the arc, the initial arc length should be controlled at 20mm. During the melting process, the arc length must be controlled at 40mm (i.e., 0.042φ). Observe the state of the molten pool during the melting process and check the surface of the crucible after it is taken out of the furnace. When melting to the vicinity of the weld, the melting voltage should be reduced to 75% of the set value and the melting time in the weld area should be 1.2 times the time. The transition at the weld should be smooth.

[0047] Depend on Figure 12 It can be seen that the molten pool is stable and there is no splashing during the smelting process; from Figure 13 It can be seen that the surface of the crucible is flat after it is taken out of the furnace, and there is no arcing phenomenon on the crucible wall.

[0048] As can be seen from the above embodiments, the present invention achieves complete elimination of the crucible wall arcing phenomenon in the VAR melting process of high Cl sponge titanium by optimizing the electrode block structure and coordinating process parameters, forming a closed-loop control from multiple dimensions such as gas generation, discharge, and arc stability. This ensures the batch operation of the production process and effectively reduces production costs in the process of preparing large-diameter high-performance titanium alloy ingots for aerospace applications.

[0049] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0050] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for eliminating arcing on the crucible wall during the VAR melting process of titanium alloys, characterized in that, By preventing moisture absorption from high-Cl content sponge titanium, consumable electrodes, and electrode blocks, and by employing multi-row fast degassing and short-arc melting during the VAR melting process, the arcing phenomenon on the crucible wall during the VAR melting of high-Cl sponge titanium can be completely eliminated.

2. A method for eliminating arcing on the crucible wall during the VAR melting process of titanium alloys, characterized in that, Includes the following steps: Step 1: Strict moisture-proof treatment is applied to high-Cl content sponge titanium, electrode blocks with dedicated exhaust channels prepared from high-Cl content sponge titanium and intermediate alloys, and consumable electrodes. Step 2: Place the consumable electrode in a matching crucible and adjust its position relative to the crucible. Then, load it into a vacuum consumable arc furnace and evacuate it to the pre-vacuum level and leakage rate. Step 3: Use a stepped, long-term preheating method to initiate and preheat the consumable electrode; Step 4: The preheated consumable electrode is melted using a short-arc melting process. When the melting reaches the vicinity of the weld, a low-voltage weld transition is used to complete the melting at the weld.

3. The method for eliminating arcing on the crucible wall during the VAR melting process of titanium alloys according to claim 2, characterized in that, In step 1, the moisture-proof treatment specifically involves: storing the high Cl content sponge titanium in a dry inert gas sealed protective container with a dew point ≤ -40℃, and strictly controlling the storage period to within 72 hours after opening; and placing the consumable electrode and electrode block in an environment with a temperature of 50~90℃ and a relative humidity ≤ 40%, with a placement period of ≤ 48 hours.

4. The method for eliminating arcing on the crucible wall during the VAR melting process of titanium alloys according to claim 2, characterized in that, In step 1, the electrode block of the dedicated exhaust channel structure is specifically configured as follows: n uniformly distributed radial exhaust channels with a diameter of D are arranged longitudinally along the assembled electrode block, and the center-to-center distance of each exhaust channel is L1, and 40mm≤L1≤L / 2, where n≥1, and L is the longitudinal length of each electrode block; m uniformly distributed longitudinal exhaust channels with a diameter of D are arranged radially along the electrode block, and the center-to-center distance of adjacent exhaust channels is W1, and 40mm≤W1≤W / 2, where m≥1, and W is the width of the electrode block; D and the circumcircle diameter Φ of the electrode block satisfy: D=(0.05-0.10)Φ, and D≥15mm; the radial exhaust channels and the axial exhaust channels are interconnected to form a three-dimensional exhaust network.

5. The method for eliminating arcing on the crucible wall during the VAR melting process of titanium alloys according to claim 2, characterized in that, In step 2, the diameter Φ of the consumable electrode and the diameter φ of the crucible satisfy Φ=(0.7-0.9)φ. The adjustment of the position of the consumable electrode relative to the crucible is specifically as follows: the distance deviation between the consumable electrode and four points evenly distributed along the circumference of the crucible is ≤10mm.

6. The method for eliminating arcing on the crucible wall during the VAR melting process of titanium alloys according to claim 2, characterized in that, In step 2, the pre-vacuum degree is ≤1Pa and the leakage rate is ≤0.8Pa / min.

7. The method for eliminating arcing on the crucible wall during the VAR melting process of titanium alloys according to claim 2, characterized in that, In step 3, the stepped long-term preheating arc-starting process specifically includes: First stage: Arc ignition current range 3~5kA, and holding time 6~10min. This stage is the initial heating stage of the consumable electrode. The vacuum control in the furnace is ≤1Pa. Second stage: The current is increased from 0.5 to 2 min to 5 to 6.5 kA and maintained at this current for 8 to 15 min. During this stage, the consumable electrode is preheated and then the exhaust begins. The vacuum degree inside the furnace should be controlled at 1 to 5 Pa. The third stage: the current is increased from 0.5 to 2 min to 7 to 9 kA and maintained at this current for 15 to 30 min. During this stage, the consumable electrode is vented at high temperature without melting, and the vacuum degree in the furnace is controlled at 1 to 5 Pa. Fourth stage: The current is directly increased to the melting current set by the process in 2~30 minutes. At this time, the normal melting state of the consumable electrode is entered. During this stage, the vacuum degree in the furnace is maintained at ≤10Pa throughout the process, and there is no need to start the booster pump.

8. The method for eliminating arcing on the crucible wall during the VAR melting process of titanium alloys according to claim 2, characterized in that, In step 4, the low-voltage weld transition specifically involves reducing the voltage at the weld to 70-80% of the rated voltage when the weld reaches the position of the consumable electrode. This reduction lasts for 1.2-1.5 times the melting time of the weld area, thus avoiding arc shift caused by sudden structural changes at the weld when the voltage increases.

9. The method for eliminating arcing on the crucible wall during the VAR melting process of titanium alloys according to claim 2, characterized in that, In step 4, the short-arc melting process specifically involves controlling the initial arc length to 5-30 mm during arc initiation; and controlling the arc length to (0.01-0.07)φ during the melting process, while ensuring it is within 5-40 mm to reduce the impact of gas disturbance on the electric arc, where φ is the crucible diameter.

10. The application of the method for eliminating crucible wall arcing during the VAR melting process of titanium alloys as described in any one of claims 1 to 9 in the preparation of large-diameter high-performance titanium alloy ingots for aerospace applications.

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