External magnetic field subsection control equipment and method for vacuum consumable electric arc furnace

Abstract

The invention belongs to the technical field of special steel and high-temperature alloy smelting, and relates to an external magnetic field subsection control device and method for a vacuum consumable electric arc furnace. The subsection control equipment for the applied magnetic field comprises a coil, an excitation power supply, a magnetic field shielding cover and a clamping and moving device. The two sets of coils are mounted on the outer side of the crucible and are powered by the two sets of excitation power supplies to generate a longitudinal magnetic field; the two sets of coils are arranged up and down, are fixed on the clamping device and can move along with the height of an electric arc and the height of a molten pool in the smelting process. A magnetic field shielding cover is arranged between the two coils, interference of a lower changing magnetic field on an upper magnetic field is avoided, and the magnetic field shielding cover moves along with the whole device. The upper coil is located at the electrode end face height and is powered by a direct-current power supply; and the power supply is a positive and negative variable direct-current power supply. Starting from a VAR electric arc, molten drop and molten pool control process, the invention provides a universal device for enhancing VAR smelting stability and improving vacuum consumable remelting ingot uniformity by improving smelting equipment, and the device has a good market application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of special steel and high-temperature alloy smelting, and relates to an external magnetic field segmented control device and method for a vacuum consumable arc furnace. Background Art

[0002] Vacuum arc remelting (VAR) is a refining process that uses an arc generated between a consumable electrode and a water-cooled crucible under vacuum conditions to melt the electrode. The molten droplets then fall into the crucible and rapidly solidify to form an ingot. As the electrode melts, the high-temperature arc between the electrode and the molten pool dissociates and removes volatile components and non-metallic inclusions, thereby refining the alloy. The VAR process remelts the electrode layer by layer, improving the uniformity and density of the ingot, reducing defects, and ultimately improving the processability and mechanical properties of the ingot. This makes it a key technology for preparing specialty alloys such as bearing steel and high-temperature alloys. The stability of the arc during the melting process determines the continuity and uniformity of the molten droplets, while the flow of the molten pool determines the uniformity of the ingot's composition distribution, ultimately directly affecting the solidification quality of the ingot.

[0003] At present, there are still deficiencies in the control of arc, molten droplet and molten pool flow in the VAR melting process. For example, patent CN110793321A discloses an arc control device and method for improving the surface quality of titanium ingots. This method controls the deflection angle of the melting arc through the Lorentz force to improve the melting stability, but does not consider the effect of the generated constant magnetic field on the stirring of the molten pool, which is not conducive to the coordinated control of the molten pool profile; patent CN111321306A discloses a method for manufacturing titanium alloy castings. This method uses a unidirectional rotating magnetic field generator to stir the melt, but the stirring in a constant direction will produce momentum accumulation and deepen the molten pool, which is not conducive to controlling macro-segregation and cannot ensure high uniformity of the ingot composition while stabilizing the melting.

[0004] The VAR arc is a stream of charged particles, and its motion and shape can be changed by applying an external magnetic field. The arc that diffuses and deflects toward the mold will rotate around the arc's central axis under the Lorentz force of a constant longitudinal magnetic field, preventing arc diffusion and thereby improving the stability of the smelting process. The longitudinal magnetic field increases the electromagnetic force acting on the electrode tip, increasing the number of transition droplets, refining the droplets, and thereby enhancing the arc's de-inclusion effect. The longitudinal magnetic field also has a stirring effect on the molten pool, but the stirring direction of the constant magnetic field is not conducive to sufficient solute diffusion. Applying an external AC reversing magnetic field can enhance convection within the molten pool, promote uniform diffusion of composition and temperature, and inhibit segregation formation. By applying different types of magnetic fields in the arc zone and molten pool zone, both smelting stability and ingot composition uniformity can be improved. Summary of the Invention

[0005] Aiming at the VAR smelting process, the present invention provides an external magnetic field segmented control device for a vacuum consumable arc furnace.

[0006] The technical solution adopted in the present invention is as follows:

[0007] A segmented control device for an external magnetic field in a vacuum consumable arc furnace comprises a coil, an excitation power supply, a magnetic field shield, and a clamping and moving device. Two sets of coils are mounted on the outside of the crucible, each powered by two excitation power supplies to generate a longitudinal magnetic field. The two sets of coils are arranged one above the other and are fixed to a clamping device, allowing them to move with the arc height and the molten pool height during the smelting process. A magnetic field shield is provided between the two sets of coils to prevent the changing magnetic field below from interfering with the upper magnetic field. The magnetic field shield moves with the entire device. The upper coil is located at the height of the electrode end face and is powered by a DC power supply. The lower coil is used to stir the molten pool, and the power supply is a DC power supply with variable positive and negative poles.

[0008] The upper coil stabilizes the melting arc and refines the droplets. The magnetic field strength can be adjusted based on melting process parameters such as current, voltage, and inter-electrode spacing. The lower coil stirs the molten pool. To avoid momentum accumulation and deepening caused by a fixed magnetic field direction, a DC power supply with variable positive and negative polarity is used. This enhances the stirring effect of the applied magnetic field on the molten pool, helping to enhance compositional uniformity and suppress segregation defects. During the melting process, the gripping device's movement rate is adjusted according to changes in the melting speed to ensure that the two magnetic fields precisely act on the arc and molten pool regions.

[0009] The electrodes melt and converge to form molten droplets. When the droplets connect the electrodes and the molten pool surface, longitudinal currents are generated in the droplets, generating a horizontal Lorentz force that exerts a radial compressive force on the droplets proportional to the square of the smelting current. By adding a longitudinal magnetic field, a downward force is exerted on the droplets, promoting contact between the droplets and the molten pool surface, achieving droplet refinement. At the same time, the horizontal magnetic field itself prevents droplets from splashing onto the mold surface, affecting the heat dissipation and solidification of the ingot, thereby improving the surface quality of the ingot. The arc close to the molten pool surface retains its original lateral velocity, maintaining the width of the high-temperature zone on the molten pool surface and preventing excessive overheating that may lead to an excessive depth in the center of the molten pool.

[0010] The above-mentioned vacuum consumable arc furnace has an external magnetic field segmented control device, and the melting process is as follows:

[0011] (1) Electrode preparation. Consumable electrodes can be prepared by vacuum induction melting (VIM) or electroslag remelting (ESR);

[0012] (2) Electrode annealing. The consumable electrodes produced by VIM casting have large internal stress. After the ingot is completely solidified and demolded, it is sent to the annealing furnace and annealed in the annealing furnace for 7 to 15 hours to remove the internal stress of the ingot and reduce the local heat during the remelting process that causes cracking. The annealing temperature is set to 150 to 350 °C below the solidus temperature of the alloy;

[0013] (3) Electrode assembly. After the electrodes are annealed and cooled to room temperature, electrode welding is performed to connect the dummy electrode and the consumable electrode;

[0014] (4) Coil position initialization. The segmented coil moves to the bottom of the crystallizer and waits;

[0015] (5) Equipment safety inspection. After the electrodes and crucibles are hoisted, check the air tightness of the equipment. Arc melting can only be started if the air leakage rate is ≤0.15 Pa / min;

[0016] (6) VAR arc starting stage. Set the arc starting current to 2~3 kA and the voltage to 15~25 V, and gradually increase the power to 7~~9 kA and 25~30 V. Use high power to quickly melt the electrode to create a molten pool. After the distance between the molten pool surface and the bottom of the crystallizer reaches 10-15% of the crystallizer diameter, gradually reduce the power until the power and droplet short-circuit time remain stable and reach the set range for stable melting. The total arc starting time is 60-120 min.

[0017] (7) VAR stable melting stage. The corresponding melting rate R is calculated and set according to the empirical formula (1) based on the ingot diameter. m The weight change of the electrode is monitored by the weight sensor of the dummy electrode, and the upward speed V is calculated according to the moving speed of the electrode end surface by the empirical formula (2). B , dynamically adjust the height of the coil clamping device to always keep the upper coil aligned with the inter-electrode arc area. The upper coil excitation current is set to DC 15~35 A, and the magnetic field strength H e The direction of the magnetic field is determined by the empirical formula (3) according to the melting current and the ingot diameter. The excitation current of the lower coil is set to 20~40 A DC, and the magnetic field intensity H m The direction of the magnetic field is changed every 1 to 3 minutes, as determined by the empirical formula (4) based on the melting rate and ingot dendrites.

[0018] R m = ρπ(0.0085r i 2 +0.00964r i 3 -0.106r i 4 ) (1)

[0019] V B = ρπ (2)

[0020] (3)

[0021] (4)

[0022] Where ρ is the liquid phase density of the alloy, kg / m 3 ; r i is the ingot diameter, m; Δm is the electrode weight change, kg; k is the electrode filling ratio, 0.5~0.9; is the magnetic permeability of the alloy liquid phase, H / m; α and is the alloy-related correction factor, 0.3-0.7;

[0023] (8) During the VAR hot capping stage, after the electrode melts to 90%, the voltage and current are gradually reduced to 20-25 V and 3-4 kA. The coil magnetic field intensity decreases synchronously with the melting rate according to the above formula (4), and the stirring is weakened until the melting is completed.

[0024] (9) When the melting rate drops to 1 / 5 of the stable melting rate, the equipment is powered off and the VAR melting is ended.

[0025] The beneficial effects of the present invention are:

[0026] The present invention starts with the VAR arc, molten droplet and molten pool control process, and by improving the smelting equipment, provides a universal device for enhancing VAR smelting stability and improving the uniformity of vacuum consumable remelting ingots, which has good market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the arc control device of the present invention.

[0028] Figure 2 Schematic diagram of the magnetic field effect in the arc zone and molten pool zone of the present invention.

[0029] In the figure: 1 consumable electrode; 2 arc; 3 molten pool; 4 ingot; 5 water-cooled crystallizer; 6 arc stabilizing coil; 7 magnetic field shield;

[0030] 8. Molten pool stirring coil; 9. Arc zone current and magnetic force direction; 10. Molten pool zone current and variable magnetic force direction. Specific embodiments

[0031] The specific embodiments of the present invention are described in detail below in conjunction with the technical solutions and drawings.

[0032] Example 1: Vacuum consumable remelting of Φ320 mm bearing steel No. 1

[0033] (1) Electrode preparation. Consumable electrodes can be prepared by vacuum induction melting (VIM) or electroslag remelting (ESR);

[0034] (2) Electrode annealing. The consumable electrodes produced by VIM casting have large internal stress. After the ingot is completely solidified and demolded, it is sent to the annealing furnace and annealed in the annealing furnace for 9 hours to remove the internal stress of the ingot and reduce the local heat during the remelting process that causes cracking. The annealing temperature is set to 1050 °C below the alloy solidus temperature;

[0035] (3) Electrode assembly. After the electrodes are annealed and cooled to room temperature, electrode welding is performed to connect the dummy electrode and the consumable electrode. The electrode diameter is 250 mm.

[0036] (4) Coil position initialization. Move the external coils (6, 7, 8) to the bottom of the mold and wait for the smelting to begin;

[0037] (5) Equipment safety inspection. After the electrodes and crucibles are hoisted, check the air tightness of the equipment. Arc melting can only be started if the air leakage rate is ≤0.15 Pa / min;

[0038] (6) VAR arc starting stage. Set the arc starting current to 2.4 kA and the voltage to 18 V, and gradually increase the power to 8 kA and 22 V. Quickly melt the electrode to form a molten pool. After the distance between the molten pool surface and the bottom of the crystallizer reaches 30 mm, gradually reduce the power until the power and the droplet short-circuit time remain stable and reach the set range for stable melting. The total arc starting time is 80 min.

[0039] (7) VAR stable melting stage. The corresponding melting rate is set to 4.2 kg / min according to the ingot shape. The weight change of the electrode is monitored by the weight sensor of the dummy electrode. The upward movement speed of the coil clamping device is dynamically adjusted to 0.0073 m / min according to the movement speed of the electrode end surface, and the upper coil is always kept aligned with the inter-electrode arc area. The excitation current of the upper coil is set to 23A DC, the magnetic field strength is 40 Gauss, and the magnetic field direction remains unchanged; the excitation current of the lower coil is set to 32A DC, the magnetic field strength is 55 Gauss, and the magnetic field direction changes every 1 minute;

[0040] (8) During the VAR hot capping stage, after the electrode melts to 90%, the voltage and current are gradually reduced to 20 V and 3 kA. The magnetic field strength of the coil is reduced synchronously with the melting power according to the above formula. The excitation current of the upper coil is slowly reduced to 15 A, and the excitation current of the lower coil is 25 A. While maintaining the arc stability, the stirring is weakened until the end of melting.

[0041] (9) When the melting rate drops to 0.7 kg / min, the equipment is powered off and the VAR melting ends.

[0042] Example 2: Φ580mm high-temperature alloy 2# vacuum consumable remelting smelting

[0043] (1) Electrode preparation. Consumable electrodes can be prepared by vacuum induction melting (VIM) or electroslag remelting (ESR);

[0044] (2) Electrode annealing. The consumable electrodes produced by VIM casting have large internal stress. After the ingot is completely solidified and demolded, it is sent to the annealing furnace and annealed in the annealing furnace for 12 hours to remove the internal stress of the ingot and reduce the local heat during the remelting process that causes cracking. The annealing temperature is set to 1120 °C below the alloy solidus temperature;

[0045] (3) Electrode assembly. After the electrodes are annealed and cooled to room temperature, electrode welding is performed to connect the dummy electrode and the consumable electrode. The electrode diameter is 460 mm.

[0046] (4) Coil position initialization. Move the external coils (6, 7, 8) to the bottom of the mold and wait for the smelting to begin;

[0047] (5) Equipment safety inspection. After the electrodes and crucibles are hoisted, check the air tightness of the equipment. Arc melting can only be started if the air leakage rate is ≤0.15 Pa / min;

[0048] (6) VAR arc starting stage. Set the arc starting current to 3.2 kA and the voltage to 19.2 V, and gradually increase the power to 8.7 kA and 24 V. Rapidly melt the electrode to form a molten pool. After the distance between the molten pool surface and the bottom of the crystallizer reaches 60 mm, gradually reduce the power until the power and the droplet short-circuit time remain stable and reach the set range for stable melting. The total arc starting time is 100 min.

[0049] (7) VAR stable melting stage. The corresponding melting rate is set to 4.6 kg / min according to the ingot shape. The weight change of the electrode is monitored by the weight sensor of the dummy electrode. The upward movement speed of the coil clamping device is dynamically adjusted to 0.0024 m / min according to the movement speed of the electrode end surface, and the upper coil is always kept aligned with the inter-electrode arc area. The excitation current of the upper coil is set to 32A DC, the magnetic field strength is 60 Gauss, and the magnetic field direction remains unchanged; the excitation current of the lower coil is set to 38A DC, the magnetic field strength is 70 Gauss, and the magnetic field direction changes every 3 minutes;

[0050] (8) During the VAR hot capping stage, after the electrode melts to 90%, the voltage and current are gradually reduced to 22 V and 3.1 kA. The coil magnetic field intensity is reduced synchronously with the melting power according to the above formula. The excitation current of the upper coil is slowly reduced to 20 A, and the excitation current of the lower coil is 30 A. While maintaining the arc stability, the stirring is weakened until the end of melting.

[0051] (9) When the melting rate drops to 0.8 kg / min, the equipment is powered off and the VAR melting ends.

[0052] Example 3: Φ180 mm high-temperature alloy 2# vacuum consumable remelting smelting

[0053] (1) Electrode preparation. Consumable electrodes can be prepared by vacuum induction melting (VIM) or electroslag remelting (ESR);

[0054] (2) Electrode annealing. The consumable electrodes produced by VIM casting have large internal stress. After the ingot is completely solidified and demolded, it is sent to the annealing furnace and annealed in the annealing furnace for 7 hours to remove the internal stress of the ingot and reduce the local heat during the remelting process that causes cracking. The annealing temperature is set to 1200 °C below the alloy solidus temperature;

[0055] (3) Electrode assembly. After the electrodes are annealed and cooled to room temperature, electrode welding is performed to connect the dummy electrode and the consumable electrode. The electrode diameter is 120 mm.

[0056] (4) Coil position initialization. Move the external coils (6, 7, 8) to the bottom of the mold and wait for the smelting to begin;

[0057] (5) Equipment safety inspection. After the electrodes and crucibles are hoisted, check the air tightness of the equipment. Arc melting can only be started if the air leakage rate is ≤0.15 Pa / min;

[0058] (6) VAR arc starting stage. Set the arc starting current to 2.2 kA and the voltage to 17 V, and gradually increase the power to 7.5 kA and 20 V. Rapidly melt the electrode to form a molten pool. After the distance between the molten pool surface and the bottom of the crystallizer reaches 26 mm, gradually reduce the power until the power and the droplet short-circuit time remain stable and reach the set range for stable melting. The total arc starting time is 60 min.

[0059] (7) VAR stable melting stage. The corresponding melting rate is set to 1.6 kg / min according to the ingot shape. The weight change of the electrode is monitored by the weight sensor of the dummy electrode. The upward movement speed of the coil clamping device is dynamically adjusted to 0.0085 m / min according to the movement speed of the electrode end surface, and the upper coil is always kept aligned with the inter-electrode arc area. The excitation current of the upper coil is set to 20A DC, the magnetic field strength is 30 Gauss, and the magnetic field direction remains unchanged; the excitation current of the lower coil is set to 28A DC, the magnetic field strength is 40 Gauss, and the magnetic field direction changes every 1 minute;

[0060] (8) VAR hot capping stage: after the electrode melts to 90%, the voltage and current are gradually reduced to 18 V and 3.0 kA. The magnetic field strength of the coil is reduced synchronously with the melting power according to the above formula. The excitation current of the upper coil is slowly reduced to 12 A, and the excitation current of the lower coil is 18 A. While maintaining the arc stability, the stirring is weakened until the end of melting.

[0061] (9) When the melting rate drops to 0.3 kg / min, the equipment is powered off and the VAR melting ends.

Claims

1. An external magnetic field segmented control device for a vacuum consumable arc furnace, characterized in that: It includes coils, excitation power supplies, and a clamping and moving device; two sets of coils are installed on the outside of the crucible, and the two sets of coils are powered by two sets of excitation power supplies to generate a longitudinal magnetic field; the two sets of coils are arranged up and down, and are both fixed on the clamping device, and can move with the arc height and the molten pool height during the smelting process; the upper coil is located at the height of the electrode end face and is powered by a DC power supply; the lower coil is used to stir the molten pool, and the power supply selects a DC power supply with variable positive and negative poles.

2. The external magnetic field segmented control device for a vacuum consumable arc furnace according to claim 1, characterized in that: It also includes a magnetic field shielding cover, which is arranged between the two sets of coils to prevent the lower changing magnetic field from interfering with the upper magnetic field. The magnetic field shielding cover moves with the entire device.

3. A method for controlling the external magnetic field segmented device of a vacuum consumable arc furnace according to claim 1 or 2, characterized by the following steps: (1) Electrode preparation: Consumable electrodes can be prepared by vacuum induction melting (VIM) or electroslag remelting (ESR); (2) Electrode annealing treatment: There is a large stress inside the consumable electrode produced by VIM casting. After the ingot is completely solidified and demolded, it is sent to the annealing furnace and annealed in the annealing furnace for 7 to 15 hours to remove the internal stress of the ingot and reduce the local heating during the remelting process that causes cracking. The annealing temperature is set to 150 to 350 °C below the solidus temperature of the alloy. (3) Electrode assembly: After the electrodes are annealed and cooled to room temperature, electrode welding is performed to connect the dummy electrode and the consumable electrode; (4) Coil position initialization; segmented coil moves to the bottom of the crystallizer and waits; (5) Equipment safety inspection: After the electrodes and crucibles are hoisted, check the air tightness of the equipment. The arc melting can only be started if the air leakage rate is ≤0.15 Pa / min; (6) VAR arc starting stage: set the arc starting current to 2~3 kA and the voltage to 15~25 V, and gradually increase the power to 7~~9 kA and 25~30 V. The electrode is melted quickly at high power to make a molten pool. After the distance between the molten pool liquid level and the bottom of the crystallizer reaches 10-15% of the crystallizer diameter, the power is gradually reduced until the power and the droplet short-circuit time remain stable and reach the set range of stable melting. The total arc starting time is 60-120 min. (7) VAR stable melting stage; according to the ingot diameter, the corresponding melting rate R is calculated and set by the empirical formula (1). m The weight change of the electrode is monitored by the weight sensor of the dummy electrode, and the upward speed V is calculated according to the moving speed of the electrode end surface by the empirical formula (2). B , dynamically adjust the height of the coil clamping device to always keep the upper coil aligned with the inter-electrode arc area; the upper coil excitation current is set to DC 15~35 A, and the magnetic field intensity H e The direction of the magnetic field is determined by the empirical formula (3) according to the melting current and the ingot diameter. The excitation current of the lower coil is set to 20~40 A DC, and the magnetic field intensity H m The direction of the magnetic field is changed every 1 to 3 minutes, as determined by the empirical formula (4) based on the melting rate and ingot dendrites. R m = ρπ(0.0085r i 2 +0.00964r i 3 -0.106r i 4 ) (1), V B = rp (2), （3）， （4）， Where ρ is the liquid phase density of the alloy, kg / m 3 ; r i is the ingot diameter, m; Δm is the electrode weight change, kg; k is the electrode filling ratio, 0.5~0.9; is the magnetic permeability of the alloy liquid phase, H / m; α and is the alloy-related correction factor, 0.3-0.7; (8) During the VAR hot capping stage, after the electrode melts to 90%, the voltage and current are gradually reduced to 20-25 V and 3-4 kA. The coil magnetic field intensity decreases synchronously with the melting rate according to the above formula (4), and the stirring is weakened until the melting is completed. (9) When the melting rate drops to 1 / 5 of the stable melting rate, the equipment is powered off and the VAR melting is ended.

4. The method for controlling the equipment of the vacuum consumable arc furnace by applying an external magnetic field in sections according to claim 3, characterized in that: A method for vacuum consumable remelting and smelting of Φ320 mm bearing steel No. 1 includes the following steps: (1) Electrode preparation: Consumable electrodes can be prepared by vacuum induction melting (VIM) or electroslag remelting (ESR); (2) Electrode annealing treatment: There is a large stress inside the consumable electrode produced by VIM casting. After the ingot is completely solidified and demolded, it is sent to the annealing furnace and annealed in the annealing furnace for 9 hours to remove the internal stress of the ingot and reduce the local heating during the remelting process that causes cracking. The annealing temperature is set to 1050 °C below the alloy solidus temperature. (3) Electrode assembly: After the electrodes are annealed and cooled to room temperature, electrode welding is performed to connect the dummy electrode and the consumable electrode. The electrode diameter is 250 mm. (4) Initialize the coil position; move the external coils (6, 7, 8) to the bottom of the mold and wait for the smelting to begin; (5) Equipment safety inspection: After the electrodes and crucibles are hoisted, check the air tightness of the equipment. The arc melting can only be started if the air leakage rate is ≤0.15 Pa / min; (6) VAR arc stage; Set the arc starting current to 2.4 kA and the voltage to 18 V, and gradually increase the power to 8 kA and 22 V to quickly melt the electrode to form a molten pool. After the distance between the molten pool surface and the bottom of the crystallizer reaches 30 mm, gradually reduce the power until the power and droplet short-circuit time remain stable and reach the set range for stable melting. The total arc starting time is 80 min. (7) VAR stable melting stage; the corresponding melting rate is set to 4.2 kg / min according to the ingot shape, the weight change of the electrode is monitored by the weight sensor of the dummy electrode, and the upward movement speed of the coil clamping device is dynamically adjusted to 0.0073 m / min according to the movement speed of the electrode end surface, and the upper coil is always kept aligned with the inter-electrode arc area; the excitation current of the upper coil is set to 23 A DC, the magnetic field strength is 40 Gauss, and the magnetic field direction remains unchanged; the excitation current of the lower coil is set to 32 A DC, the magnetic field strength is 55 Gauss, and the magnetic field direction changes every 1 min; (8) During the VAR hot capping stage, after the electrode melts to 90%, the voltage and current are gradually reduced to 20 V and 3 kA. The magnetic field strength of the coil is reduced synchronously with the melting power according to the above formula. The excitation current of the upper coil is slowly reduced to 15 A, and the excitation current of the lower coil is 25 A. While maintaining the arc stability, the stirring is weakened until the end of melting. (9) When the melting rate drops to 0.7 kg / min, the equipment is powered off and the VAR melting ends.

5. The method for controlling the equipment of the vacuum consumable arc furnace by applying an external magnetic field in sections according to claim 3, characterized in that: The Φ580mm high-temperature alloy 2# vacuum consumable remelting smelting process includes the following steps: (1) Electrode preparation: Consumable electrodes can be prepared by vacuum induction melting (VIM) or electroslag remelting (ESR); (2) Electrode annealing treatment: There is a large stress inside the consumable electrode produced by VIM casting. After the ingot is completely solidified and demolded, it is sent to the annealing furnace and annealed in the annealing furnace for 12 hours to remove the internal stress of the ingot and reduce the local heating during the remelting process that causes cracking. The annealing temperature is set to 1120 °C below the alloy solidus temperature. (3) Electrode assembly: After the electrodes are annealed and cooled to room temperature, electrode welding is performed to connect the dummy electrode and the consumable electrode. The electrode diameter is 460 mm. (4) Initialize the coil position; move the external coils (6, 7, 8) to the bottom of the mold and wait for the smelting to begin; (5) Equipment safety inspection: After the electrodes and crucibles are hoisted, check the air tightness of the equipment. The arc melting can only be started if the air leakage rate is ≤0.15 Pa / min; (6) VAR arc starting stage: set the arc starting current to 3.2 kA and the voltage to 19.2 V, and gradually increase the power to 8.7 kA and 24 V, quickly melt the electrode to make a molten pool. After the distance between the molten pool liquid level and the bottom of the crystallizer reaches 60 mm, gradually reduce the power until the power and the droplet short-circuit time remain stable and reach the set range of stable melting. The total arc starting time is 100 min. (7) VAR stable melting stage; the corresponding melting rate is set to 4.6 kg / min according to the ingot shape, the weight change of the electrode is monitored by the weight sensor of the dummy electrode, and the upward speed of the coil clamping device is dynamically adjusted to 0.0024 m / min according to the moving speed of the electrode end surface, and the upper coil is always kept aligned with the inter-electrode arc area; the excitation current of the upper coil is set to 32 A DC, the magnetic field strength is 60 Gauss, and the magnetic field direction remains unchanged; the excitation current of the lower coil is set to 38 A DC, the magnetic field strength is 70 Gauss, and the magnetic field direction changes every 3 minutes; (8) During the VAR hot capping stage, after the electrode melts to 90%, the voltage and current are gradually reduced to 22 V and 3.1 kA. The coil magnetic field intensity is reduced synchronously with the melting power according to the above formula. The excitation current of the upper coil is slowly reduced to 20 A, and the excitation current of the lower coil is 30 A. While maintaining the arc stability, the stirring is weakened until the end of melting. (9) When the melting rate drops to 0.8 kg / min, the equipment is powered off and the VAR melting ends.

6. The method for controlling the equipment of the vacuum consumable arc furnace by applying an external magnetic field in sections according to claim 3, characterized in that: The Φ180 mm high-temperature alloy 2# vacuum consumable remelting smelting process includes the following steps: (1) Electrode preparation: Consumable electrodes can be prepared by vacuum induction melting (VIM) or electroslag remelting (ESR); (2) Electrode annealing treatment: There is a large stress inside the consumable electrode produced by VIM casting. After the ingot is completely solidified and demolded, it is sent to the annealing furnace and annealed in the annealing furnace for 7 hours to remove the internal stress of the ingot and reduce the local heating during the remelting process that causes cracking. The annealing temperature is set to 1200 °C below the alloy solidus temperature. (3) Electrode assembly: After the electrodes are annealed and cooled to room temperature, electrode welding is performed to connect the dummy electrode and the consumable electrode. The electrode diameter is 120 mm. (4) Initialize the coil position; move the external coils (6, 7, 8) to the bottom of the mold and wait for the smelting to begin; (5) Equipment safety inspection: After the electrodes and crucibles are hoisted, check the air tightness of the equipment. The arc melting can only be started if the air leakage rate is ≤0.15 Pa / min; (6) VAR arc starting stage: set the arc starting current to 2.2 kA and the voltage to 17 V, and gradually increase the power to 7.5 kA and 20 V, quickly melt the electrode to form a molten pool. After the distance between the molten pool liquid level and the bottom of the crystallizer reaches 26 mm, gradually reduce the power until the power and the droplet short-circuit time remain stable and reach the set range of stable melting. The total arc starting time is 60 min. (7) VAR stable melting stage; the corresponding melting rate is set to 1.6 kg / min according to the ingot shape, the weight change of the electrode is monitored by the weight sensor of the dummy electrode, and the upward movement speed of the coil clamping device is dynamically adjusted to 0.0085 m / min according to the movement speed of the electrode end surface, and the upper coil is always kept aligned with the inter-electrode arc area; the excitation current of the upper coil is set to 20 A DC, the magnetic field strength is 30 Gauss, and the magnetic field direction remains unchanged; the excitation current of the lower coil is set to 28 A DC, the magnetic field strength is 40 Gauss, and the magnetic field direction changes every 1 min; (8) VAR hot capping stage: after the electrode melts to 90%, the voltage and current are gradually reduced to 18 V and 3.0 kA. The magnetic field strength of the coil is reduced synchronously with the melting power according to the above formula. The excitation current of the upper coil is slowly reduced to 12 A, and the excitation current of the lower coil is 18 A. While maintaining the arc stability, the stirring is weakened until the end of melting. (9) When the melting rate drops to 0.3 kg / min, the equipment is powered off and the VAR melting ends.

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