A vacuum self-consumption remelting feeding method and a vacuum self-consumption ingot smelting method

Abstract

This invention provides a feeding method for vacuum consumable remelting and a smelting method for vacuum consumable ingots. The feeding method includes: S1, feeding begins when the remaining weight of the consumable electrode is 10%–13% of the initial total weight, and the current is reduced to 90%–95% of the remelting stage current; S2, when the remaining weight of the consumable electrode is 7%–10% of the initial total weight, the current is reduced to 55%–60% of the remelting stage current, and the droplet time is reduced to 70%–80% of the remelting stage droplet time; S3, when the remaining weight of the consumable electrode is 2%–3% of the initial total weight, the current is reduced to 40%–50% of the remelting stage current, and the voltage is reduced to 80%–90% of the remelting stage voltage. The smelting method includes feeding using the above feeding method. This invention solves the shrinkage cavity defect problem after normal head and tail trimming of steel ingots produced in large vacuum consumable furnaces, improving the internal quality of the ingots.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, and in particular to a feeding method for vacuum consumable remelting and a smelting method for vacuum consumable ingots. Background Technology

[0002] Vacuum arc remelting (VAR) (also known as vacuum arc remelting) is one of the most important remelting technologies widely used in the metallurgical industry. It involves generating an electric arc in a vacuum using a DC power supply between an electrode and the bottom plate of a copper crucible placed in a water jacket. The arc heats the electrode, melting it as it descends. The melted metal forms a molten pool within the water-cooled copper crucible, where it rapidly solidifies, crystallizes, and solidifies into an ingot.

[0003] Vacuum arc remelting is generally used for refining special stainless steel, ultra-high strength steel, high-temperature alloys, etc. It is a very strictly controlled smelting technology. Compared with any other remelting technology, it can further purify the gas, trace elements, impurity elements and inclusions in steel or alloy, significantly improving the cleanliness, uniformity, fatigue resistance and fracture toughness of the ingot. The steel ingots produced are widely used in nuclear power, aerospace, military industry and civilian fields.

[0004] Vacuum arc remelting (VAR) consists of three stages: arc ignition, melting, and shrinkage compensation. The arc ignition stage is the first stage, primarily involving igniting the electric arc, rapidly transitioning it to a stable combustion state, and establishing a molten pool of a certain depth. The melting stage is the second stage, comprising the majority of the remelting process. The shrinkage compensation stage is the final stage of VAR, mainly aimed at preventing head shrinkage and internal porosity, guiding the final removal of gases and inclusions from the head, and ensuring consistency in purity and crystallinity between the head and the ingot body.

[0005] To better complete the feeding stage of consumable metal remelting and ensure a gradual shallowing of the molten pool at the end, the common practice is to gradually reduce the smelting current, thus decreasing the melting rate during the feeding stage. However, reducing the smelting current leads to an increase in arc length and a decrease in melting power. This results in a slower velocity of the nipple-shaped semi-molten metal droplets formed at the metal electrode tip, causing the cathode spot to float across the entire electrode end face. At this point, the current density is low, arc stability deteriorates, and arc creep, flashing, and glow discharge are more likely to occur. This results in the inability to timely expel gases in the later stages of melting, and the shrinkage cavities caused by the solidification of the molten steel are not effectively replenished by the upper molten steel. Furthermore, because large consumable ingots (weight ≥ 12t) have a larger cross-sectional diameter and a deeper molten pool, the current and droplets during vacuum consumable remelting feeding are highly unstable and fluctuate significantly. Compared to small-tonnage consumable remelting, large consumable ingots are more prone to defects such as shrinkage cavities and slag inclusions at the feeding end, severely affecting the feeding quality.

[0006] Currently, the instability of the feeding process leads to poor feeding effects in the production of self-consumable remelted steel ingots by steel mills, resulting in a large distance between the shrinkage cavity and the end, especially for large-tonnage self-consumable ingots. Therefore, how to improve the feeding quality of vacuum self-consumable remelted ingots (e.g., weight ≥6t, preferably ≥12t) has become an important issue that urgently needs to be addressed. Summary of the Invention

[0007] The purpose of this invention is to provide a feeding method for vacuum consumable remelting and a smelting method for vacuum consumable ingots. This feeding method solves the problems in existing feeding processes where unstable electric arcs lead to poor feeding effects in consumable remelted steel ingots, and defects such as shrinkage cavities and slag inclusions are prone to occur, especially for large-tonnage consumable ingots.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] In a first aspect, the present invention provides a shrinkage compensation method for vacuum arc remelting, comprising the following steps:

[0010] S1. Pre-feeding stage: When the remaining weight of the consumable electrode is 10% to 13% of the initial total weight of the consumable electrode, feeding begins, and the current is reduced to 90% to 95% of the current in the remelting stage.

[0011] S2, Mid-stage of feeding: When the remaining weight of the consumable electrode is 7% to 10% of the initial total weight of the consumable electrode, the current is reduced to 55% to 60% of the current in the remelting stage, and the droplet time is reduced to 70% to 80% of the droplet time in the remelting stage.

[0012] S3, Later stage of feeding: When the remaining weight of the consumable electrode is 2% to 3% of the initial total weight of the consumable electrode, the current is reduced to 40% to 50% of the current in the remelting stage, and the voltage is reduced to 80% to 90% of the voltage in the remelting stage.

[0013] Secondly, the present invention provides a method for smelting vacuum consumable ingots, comprising the following steps:

[0014] (1) A welding electrode is obtained by welding a consumable electrode and an auxiliary electrode;

[0015] (2) Place the welding electrode obtained in step (1) into the copper crystallizer and evacuate the vacuum self-consuming furnace.

[0016] (3) After the ultimate vacuum and leakage rate meet the requirements, use a large current to start the arc. The arc starting process is controlled by voltage, and the current is increased stepwise. The maximum current is 25-35% higher than the current in the melting stage.

[0017] (4) After the arc is started, the remelting stage is entered. The current and melting rate are stable during the remelting process, and droplet control is adopted.

[0018] (5) When the weight of the remaining consumable electrode reaches 10% to 13% of the total weight of the initial consumable electrode, the vacuum consumable remelting ingot is obtained by the shrinking method of vacuum consumable remelting described in the first aspect.

[0019] Furthermore, in step (1), the surface of the consumable electrode is first peeled or machined before being welded to the auxiliary electrode.

[0020] Furthermore, in step (2), the vacuum self-consuming furnace is a Consarc vacuum furnace.

[0021] Furthermore, in step (3), the ultimate vacuum degree reaches ≤1.2Pa and the leakage rate reaches ≤1.2Pa / min.

[0022] Furthermore, in step (3), the voltage is 20-25V.

[0023] Furthermore, in step (3), the arc initiation time is 60-140 min.

[0024] Furthermore, in step (3), after the ingot weight reaches 9-11% of the total weight of the consumable electrode, helium is filled into the vacuum consumable furnace.

[0025] Furthermore, in step (4), the remelting stage current is 10000-14000A; and / or the melting rate is 5-8kg / min and the droplet length is 0.4-0.8s.

[0026] Furthermore, the vacuum consumable remelting ingot is a large vacuum consumable remelting ingot with a weight of ≥6t, preferably ≥12t.

[0027] Compared with the prior art, the technical solution of the present invention has at least the following technical effects:

[0028] This invention employs a three-point control method—current, molten droplet, and voltage—for vacuum consumable remelting during the feeding stage. This ensures the feeding effect while avoiding defects such as shrinkage cavities and slag inclusions caused by arc climbing, flashing, and glow discharge. Furthermore, for large vacuum consumable ingots, it can shorten the distance from the shrinkage cavity to the end, solving the shrinkage cavity defect problem after normal head and tail trimming of steel ingots produced in large vacuum consumable furnaces. This significantly improves the internal quality of the ingots and enhances the overall product quality. Attached Figure Description

[0029] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:

[0030] Figure 1This is an image showing the defect location after the steel head at the feeding end of the vacuum consumable remelted ingot smelted in Example 1 is cut open. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0032] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0033] According to a first aspect of the present invention, a method for compensating shrinkage by vacuum arc remelting is provided, comprising the following steps:

[0034] S1. Pre-feeding stage: When the remaining weight of the consumable electrode is 10% to 13% (e.g., 11% or 12%) of the initial total weight of the consumable electrode, feeding begins. The current is reduced to 90% to 95% (e.g., 91%, 92%, 93%, or 94%) of the current in the remelting stage. By reducing the current and melting power, the molten metal is slowly replenished while maintaining the liquid molten pool, so as to reduce the shrinkage cavity of the steel ingot and improve the feeding effect.

[0035] S2, Mid-stage of shrinkage: When the remaining weight of the consumable electrode is 7% to 10% (e.g., 8% or 9%) of the initial total weight of the consumable electrode, the current is reduced to 55% to 60% (e.g., 56%, 57%, 58%, or 59%) of the current during the remelting stage, and the droplet time is reduced to 70% to 80% (e.g., 72%, 74%, 76%, or 78%) of the droplet time during the remelting stage. Current + droplet control is adopted to reduce the arc length by reducing the droplet time. After the arc length is reduced, the heat loss is reduced, the energy utilization rate is improved, and the normal formation of the nipple-shaped semi-molten droplet is ensured to achieve the purpose of arc stabilization.

[0036] S3, Later Stage of Feeding: When the remaining weight of the consumable electrode is 2%–3% (e.g., 2.2%, 2.4%, 2.6%, 2.8%) of the initial total weight, the current is reduced to 40%–50% (e.g., 42%, 44%, 46%, 48%) of the remelting stage current, and the voltage is reduced to 80%–90% (e.g., 82%, 84%, 86%, 88%) of the remelting stage voltage. Current + voltage control is used to ensure that the melting rate rebounds due to melting of the electrode edge during the final feeding stage.

[0037] According to a second aspect of the present invention, a method for smelting vacuum consumable ingots is provided, comprising the following steps:

[0038] (1) A welding electrode is obtained by welding a consumable electrode and an auxiliary electrode;

[0039] (2) Place the welding electrode obtained in step (1) into the copper crystallizer and evacuate the vacuum self-consuming furnace.

[0040] (3) After the ultimate vacuum and leakage rate meet the requirements, use a large current to start the arc. The arc starting process is controlled by voltage, and the current is increased stepwise. The maximum current is 25-35% higher than the current in the melting stage.

[0041] (4) After the arc is started, the remelting stage is entered. The current and melting rate are stable during the remelting process, and droplet control is adopted.

[0042] (5) When the remaining self-consuming electrode weight reaches 10% to 13% of the initial total self-consuming electrode weight, the vacuum self-consuming remelting feeding method described in the first aspect is used to feed the ingot to the vacuum self-consuming remelting ingot.

[0043] In the above smelting method, as an optional implementation, the consumable electrode used in this invention is obtained by vacuum induction casting.

[0044] In the above smelting method, as a preferred embodiment, in step (1), the consumable electrode is surface treated and then welded to the auxiliary electrode, that is, the surface of the consumable electrode is first peeled or machined and then welded to the auxiliary electrode.

[0045] In the above smelting method, as a preferred embodiment, in step (2), the vacuum self-consuming furnace is a Consarc vacuum furnace.

[0046] In the above smelting method, as a preferred embodiment, in step (3), the ultimate vacuum degree reaches ≤1.2Pa and the leakage rate reaches ≤1.2Pa / min.

[0047] In the above smelting method, as a preferred embodiment, the voltage in steps (3) and (4) is 20-25V.

[0048] In the above smelting method, as a preferred embodiment, in step (3), the arc ignition time is 60-140 min.

[0049] In the above smelting method, as a preferred embodiment, in step (4), the current during the remelting stage is 10000-14000A.

[0050] In the above smelting method, as a preferred embodiment, in step (4), the melting rate is set to 5-8 kg / min and the molten droplet is set to 0.3-0.8 s.

[0051] In the above smelting method, in step (4), after the ingot weight reaches 9-11% of the total weight of the initial consumable electrode, helium is filled into the vacuum consumable furnace. Filling with helium at a certain pressure can ensure uniform cooling of the steel ingot.

[0052] In the above smelting method, the vacuum consumable ingot is a large vacuum consumable remelting ingot with a weight of ≥6t, preferably ≥12t.

[0053] The present invention will now be described in further detail with reference to specific embodiments and comparative examples. It should be noted that the vacuum arc furnaces used in the following embodiments are all Consarc vacuum furnaces.

[0054] Example 1

[0055] This embodiment provides a smelting method for a 12t (Ф950mm) large vacuum consumable ingot, including the following steps:

[0056] (1) After the electrode surface is peeled or machined to ensure it is free of cracks, inclusions, oxide scale, etc., auxiliary electrodes are welded on, and then the welded electrodes are placed in the copper crystallizer. The vacuum arc furnace is evacuated, and after the ultimate vacuum degree and leakage rate meet the requirements, the smelting is started.

[0057] (2) Arc ignition: A large current is used to ignite the arc in order to quickly form a molten pool. The arc ignition time is controlled at 120 minutes. The arc ignition process is controlled by voltage, with a voltage of 24.5V. At the same time, the current is increased stepwise, with the highest current being 16700A, which is 30.5% higher than the current during normal smelting.

[0058] (3) Stable Remelting Stage: After arc ignition, the process enters the stable remelting stage. The current is set to 12800A, the voltage to 24.5V, the melting rate to 7kg / min, and the droplet setting to 0.7s. The feed rod drive will use droplet control to ensure the stability of the molten pool during the remelting process. After the consumable ingot weight reaches 9-11% of the total weight of the consumable electrode, helium gas at a certain pressure is started to be filled into the vacuum consumable furnace to ensure uniform cooling of the steel ingot. The helium system automatically controls the helium pressure in the furnace according to the set value through the regulating valve. Subsequently, the consumable furnace maintains the above parameters for remelting until the weight of the consumable electrode at the start of the shrinkage process is reached.

[0059] (4) The feeding stage adopts the current-droplet-voltage three-point control method for feeding. The specific implementation method is as follows:

[0060] (4-1) In the initial stage of feeding, current control is used. When feeding begins, the remaining weight of the consumable electrode is 1200 kg. During this stage, the current is adjusted to 12000A. Other parameters are not involved in the control and are maintained at the parameters of the smelting stage. By reducing the current, the melting power is reduced. While maintaining the liquid molten pool, the molten metal is slowly replenished to reduce the shrinkage cavity of the steel ingot and improve the feeding effect.

[0061] (4-2) During the mid-stage of the feeding process (when the remaining consumable electrode weight reaches 1000 kg), current + droplet control is adopted. The current is reduced to 7500 A, and the droplet time is reduced to 0.55 s. Other parameters are not involved in the control; the parameters of the melting stage are maintained. By reducing the droplet time, the arc length is reduced. After the arc length is reduced, the heat loss is reduced, the energy utilization rate is improved, and the normal formation of the nipple-shaped semi-molten droplets is ensured to achieve the purpose of arc stabilization.

[0062] (4-3) At the end of the feeding process (when the remaining self-consumable electrode weight reaches 350kg), arcing and flashing are very likely to occur, resulting in severe deformation of the electrode bottom. In this stage, current + voltage control is adopted, with the current reduced to 6200A, and the feed rod drive speed control changed from droplet control to voltage control, with the voltage gradually reduced to 21.9V. Other parameters are not involved in the regulation to ensure that the melting of the electrode edge does not occur in the final feeding stage, thus preventing the melting rate rebound problem.

[0063] The vacuum consumable ingot product obtained in Example 1 was sawn along the feeding end sawing line (150mm from the end). No defects were found in the cross-section of the feeding end of the consumable ingot after sawing. The sawn steel head was then cut open along the middle anatomical line (i.e., axial direction). The cut steel head is shown in the attached figure. Figure 1As shown, the defects in the core of the sawn steel head (i.e., the depth from the end) are detected, revealing the locations of shrinkage cavities and inclusions in the core of the ingot. The results show that the defects in a 12t (Ф950mm) vacuum consumable steel ingot are located 20-40mm from the end (the top of the image indicates the end). This demonstrates that by using the feeding method of this invention to produce large vacuum consumable ingots, the distance from the shrinkage cavity to the end can be shortened, solving the problem of shrinkage defects after normal head and tail cutting in large vacuum consumable furnace steelmaking ingots, significantly improving the internal quality of the ingot and thus enhancing the overall product quality.

[0064] Example 2

[0065] This embodiment provides a smelting method for 6t (Ф660mm) vacuum consumable ingots, including the following steps:

[0066] (1) After the electrode surface is peeled or machined to ensure it is free of cracks, inclusions, oxide scale, etc., the auxiliary electrode is then welded on. After that, the welded electrode ends are placed into the copper crystallizer. The vacuum arc furnace is evacuated, and after the ultimate vacuum degree and leakage rate meet the requirements, the smelting begins.

[0067] (2) Arc ignition: A large current is used to ignite the arc in order to quickly form a molten pool. The arc ignition time is controlled at 60 minutes. The arc ignition process is controlled by voltage, with a voltage of 24V. At the same time, the current is increased in steps, with the maximum current set at 14500A, which is 27% higher than the current during normal smelting.

[0068] (3) Stable Remelting Stage: After arc ignition, the process enters a stable remelting stage. The current is set to 11400A, the voltage to 24V, the melting rate to 6kg / min, and the droplet setting to 0.5s. The feed rod drive will use droplet control to ensure the stability of the molten pool during the remelting process. After the consumable ingot weight reaches 9-11% of the total weight of the consumable electrode, helium gas at a certain pressure is started to be filled into the vacuum consumable furnace to ensure uniform cooling of the steel ingot. The helium system automatically controls the helium pressure in the furnace according to the set value through the regulating valve. Subsequently, the consumable furnace maintains the above parameters for remelting until the ingot weight at the start of the shrinkage compensation is reached.

[0069] (4) The feeding stage adopts the current-droplet-voltage three-point control method for feeding. The specific implementation method is as follows:

[0070] (4-1) In the initial stage of feeding, current control is used. At the start of feeding, the remaining weight of the consumable electrode is 620 kg. The current at this stage is 10500 A. Other parameters are not involved in the control and are maintained at the parameters of the smelting stage. By reducing the current and the melting power, the molten metal is slowly added while maintaining the liquid molten pool, so as to reduce the shrinkage cavity of the steel ingot and improve the feeding effect.

[0071] (4-2) During the middle stage of the feeding process (when the remaining self-consumable electrode weight reaches 480 kg), current + droplet control is adopted. The current is reduced to 6700 A, and the droplet time is gradually reduced to 0.35 s. Other parameters are not involved in the control; the parameters of the melting stage are maintained. By reducing the droplet time, the arc length is reduced. After the arc length is reduced, the heat loss is reduced, the energy utilization rate is improved, and the normal formation of the nipple-shaped semi-molten droplets is ensured to achieve the purpose of arc stabilization.

[0072] (4-3) At the end of the feeding stage (when the remaining self-consumable electrode weight reaches 140kg), arcing and flashing are very likely to occur, resulting in severe deformation of the electrode bottom. In this stage, current + voltage control is adopted, with the current reduced to 4800A, and the feed rod drive speed control is changed from droplet control to voltage control, with the voltage reduced to 21V. Other parameters are not involved in the regulation to ensure that the melting of the electrode edge does not occur in the final feeding stage, thus preventing the melting rate rebound problem.

[0073] The vacuum consumable ingot product obtained in Example 2 was sawn along the feeding end sawing line (120mm from the end). No defects were found in the cross-section of the feeding end of the consumable ingot after sawing. The sawn steel head was cut open along the middle dissection line, and the defects in the core of the sawn steel head (i.e., the depth from the end) were inspected. The locations of shrinkage cavities and slag inclusions in the core of the end steel ingot were identified. The results showed that no shrinkage cavities or inclusion defects were found in the 6t (Ф660mm) vacuum consumable steel ingot. It can be seen that the vacuum consumable ingot produced by using the feeding method of the present invention can shorten or eliminate the distance from the shrinkage cavity to the end, solve the problem of shrinkage cavity defects after normal head and tail cutting of steel ingots produced in large vacuum consumable furnaces, greatly improve the internal quality of the ingot, and improve the quality of the product.

[0074] Comparative Example 1

[0075] Except for the feeding process in step (4), which differs from that in Example 1, the preparation process and specifications of other vacuum consumable ingot products are the same as in Example 1. The feeding process of this comparative example is as follows:

[0076] (4-1) Initial feeding stage: When feeding begins, the remaining weight of the self-consumable electrode is 1200kg. During this stage, the current gradient decreases by 10% per minute, the current of the melting stage decreases by 1% per minute, the voltage decreases by 1% per minute, and other parameters remain the same as those of the melting stage.

[0077] (4-2) During the mid-stage of feeding (when the remaining self-consumable electrode weight reaches 1000kg), the current gradient decreases by 5% per minute, the current of the melting stage decreases by 0.8% per minute, the voltage decreases by 0.8% per minute, and other parameters remain the same as those of the melting stage.

[0078] (4-3) At the end of the feeding stage (when the remaining self-consumable electrode weight reaches 350kg), the current drops to 3840A, the voltage drops by 0.8% of the melting stage voltage per minute, and other parameters remain the same as those in the melting stage.

[0079] The vacuum consumable ingot product obtained in Comparative Example 1 was sawn along the feeding end sawing line (150mm from the end). After sawing, defects were found in the cross-section of the feeding end of the consumable ingot. When the smelting current is reduced, the arc length will increase and the melting power will decrease. This will cause the speed of the nipple-shaped semi-molten metal droplets formed at the end of the metal electrode to slow down. The cathode spot will float on the entire electrode end face. At this time, the current density is low, the arc stability is poor, and it is easy to generate arc climbing, flashing and glow. As a result, the gas in the later stage of smelting cannot be discharged in time, and the shrinkage cavity caused by the solidification volume of the molten steel is not effectively replenished by the upper molten steel, which seriously affects the feeding quality.

[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for feeding by vacuum arc remelting, characterized in that, Includes the following steps: S1. Pre-feeding stage: When the remaining weight of the consumable electrode is 10% to 13% of the initial total weight of the consumable electrode, feeding begins, and the current is reduced to 90% to 95% of the current in the remelting stage; S2, Mid-stage of feeding: When the remaining weight of the consumable electrode is 7% to 10% of the initial total weight of the consumable electrode, the current is reduced to 55% to 60% of the current in the remelting stage, and the droplet time is reduced to 70% to 80% of the droplet time in the remelting stage; S3, Post-feeding stage: When the remaining weight of the consumable electrode is 2% to 3% of the initial total weight of the consumable electrode, the current is reduced to 40% to 50% of the current in the remelting stage, and the voltage is reduced to 80% to 90% of the voltage in the remelting stage.

2. A method for smelting vacuum consumable ingots, characterized in that, Includes the following steps: (1) A welding electrode is obtained by welding the consumable electrode and the auxiliary electrode; (2) Place the welding electrode obtained in step (1) into the copper crystallizer and evacuate the vacuum arc furnace; (3) After the ultimate vacuum and leakage rate meet the requirements, use a large current to start the arc. The arc starting process is controlled by voltage, and the current is increased stepwise. The maximum current is 25-35% higher than the current in the melting stage. (4) After the arc is started, the remelting process enters a stable remelting stage. The current and melting rate are stable during the remelting process, and droplet control is adopted. (5) When the remaining weight of the consumable electrode reaches 10% to 13% of the total weight of the initial consumable electrode, the vacuum consumable remelting ingot is obtained by the shrinking method of vacuum consumable remelting as described in claim 1.

3. The smelting method according to claim 2, characterized in that, In step (1), the surface of the consumable electrode is first peeled or machined before being welded to the auxiliary electrode.

4. The smelting method according to claim 2, characterized in that, In step (2), the vacuum self-consuming furnace is a Consarc vacuum furnace.

5. The smelting method according to claim 2, characterized in that, In step (3), the ultimate vacuum degree reaches ≤1.2Pa and the leakage rate reaches ≤1.2Pa / min.

6. The smelting method according to claim 2, characterized in that, In step (3), the voltage is 20-25V.

7. The smelting method according to claim 2, characterized in that, In step (3), the arc initiation time is 60-140 min.

8. The smelting method according to claim 2, characterized in that, In step (3), after the ingot weight reaches 9-11% of the total weight of the consumable electrode, helium is filled into the vacuum consumable furnace.

9. The smelting method according to claim 2, characterized in that, In step (4), the remelting current is 10000-14000A; And / or the melting rate is 5-8 kg / min and the droplet length is 0.4-0.8 s.

10. The smelting method according to claim 2, characterized in that, The vacuum consumable remelting ingot is a large vacuum consumable remelting ingot with a weight of ≥6t.

11. The smelting method according to claim 2, characterized in that, The vacuum consumable remelting ingot is a large vacuum consumable remelting ingot with a weight ≥12t.

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