Electroslag remelting crystallizer capable of adjusting conductivity

Abstract

The invention belongs to the field of metallurgical equipment, and particularly relates to a conductivity-adjustable electroslag remelting crystallizer, which comprises a crystallizer and a bottom water tank arranged at the bottom of the crystallizer, a highly-doped silicon carbide wafer layer is fixed on the inner wall of the crystallizer, the highly-doped silicon carbide wafer layer is of a straight cylindrical structure, and the bottom water tank is arranged at the bottom of the crystallizer. A circular highly-doped silicon carbide wafer plate is fixed to the top of the bottom water tank, and the bottom end of the highly-doped silicon carbide wafer layer abuts against the highly-doped silicon carbide wafer plate. The crystallizer has the advantages that the highly-doped silicon carbide wafer layer is arranged on the inner side of the crystallizer, so that more current flows out through the crystallizer on the slag bath side, the loss is reduced, and the current utilization rate is improved. And by utilizing the characteristic that the electric conductivity of the silicon carbide wafer is gradually increased along with the temperature rise and the characteristic that the steel ingot is solidified from bottom to top in the electroslag remelting process, the current distribution is dynamically controlled, and the uniformity of the solidification structure is improved.

Description

Technical Field

[0001] The invention belongs to the field of metallurgical equipment, and in particular relates to an electroslag remelting crystallizer with adjustable electrical conductivity. Background Art

[0002] Electroslag remelting (ESR) is a specialized metallurgical process that utilizes the resistance heat generated by passing an electric current through molten slag as a heat source for secondary refining and forming of metals. The core process involves inserting a consumable electrode into a pool of molten slag. The current flowing through the pool generates high temperatures, melting the electrode. The metal droplets then pass through the pool and fall into a water-cooled crystallizer, where they gradually solidify into a high-purity, dense, and uniformly composed steel ingot. This technology, originating in the 1940s, has become a key process for producing high-performance metal materials in fields such as aerospace and energy equipment.

[0003] The mold and sump are core components of electroslag remelting (ESR). Their design parameters and process control directly impact the morphology of the molten metal pool, solidification quality, and final product performance. Currently, molds are primarily classified into two categories: conductive molds, in which current is conducted through the mold to the sump; and insulating molds, in which current is conducted solely through the slag pool and electrodes, rather than through the mold.

[0004] However, the electrical conductivity of existing molds is fixed, making it impossible to dynamically adjust the current ratio flowing through the mold and the bottom water tank during the smelting process. This makes it difficult to adapt to the current distribution requirements of different smelting stages, affecting the uniformity of the molten pool thermal field and solidification structure. In addition, the inner wall of traditional molds is usually made of copper. Although it has excellent thermal conductivity, copper has a low melting point (approximately 1083°C) and is easily corroded by high-temperature ingot casting for a long time. This can cause melting loss of the copper mold inner wall, which not only shortens the equipment life but also may contaminate the ingot and affect the surface quality of the ingot.

[0005] Therefore, there is an urgent need to develop a new type of crystallizer that can dynamically adjust the conductivity, optimize the current distribution, and improve the high-temperature resistance to meet the process requirements for the preparation of high-performance metal materials. Summary of the Invention

[0006] In order to overcome the shortcomings of the existing technology, the purpose of the present invention is to provide an electroslag remelting crystallizer with adjustable electrical conductivity. By laying a highly doped silicon carbide wafer layer in the crystallizer, utilizing the characteristic that the conductivity of the silicon carbide wafer gradually increases with increasing temperature and the characteristic that the steel ingot solidifies from bottom to top during the electroslag remelting process, the current distribution is dynamically controlled to improve the uniformity of the solidification structure.

[0007] To achieve the above object, the present invention is implemented through the following technical solutions:

[0008] An electroslag remelting crystallizer with adjustable electrical conductivity includes a crystallizer and a bottom water tank arranged at the bottom of the crystallizer. A highly doped silicon carbide wafer layer is fixed to the inner wall of the crystallizer. The highly doped silicon carbide wafer layer has a straight cylindrical structure. A circular highly doped silicon carbide wafer plate is fixed to the top of the bottom water tank. The bottom end of the highly doped silicon carbide wafer layer rests on the highly doped silicon carbide wafer plate.

[0009] The inner wall of the crystallizer is welded to the highly doped silicon carbide wafer layer.

[0010] The highly doped silicon carbide wafer layer and the highly doped silicon carbide wafer plate are both doped with 6H-SIC silicon carbide wafers or 4H-SIC silicon carbide wafers.

[0011] The crystallizer comprises a water cavity which is a straight cylindrical structure. The inner side of the water cavity is fixed to the highly doped silicon carbide round crystal layer. The lower part of the water cavity is provided with a crystallizer water inlet, and the upper part is provided with a crystallizer water outlet.

[0012] A crystallizer conductive column is fixed at the bottom of the water chamber, and the crystallizer conductive column is made of pure copper; the crystallizer conductive column is connected to an external power supply.

[0013] The water inlet of the crystallizer is arranged on one side of the water cavity, and the water outlet of the crystallizer is arranged on the other side of the water cavity.

[0014] The water inlet and outlet of the crystallizer are both connected to the external pipeline through flanges.

[0015] A water inlet is provided at the bottom of the bottom water tank; a water outlet is provided on one side of the bottom water tank, and a conductive column is provided on the other side; the conductive column is made of pure copper and is connected to an external power supply.

[0016] The water inlet and outlet of the bottom water tank are both connected to the external pipeline through flanges.

[0017] When the electroslag remelting crystallizer is performing electroslag remelting, the consumable electrode is inserted into the molten slag pool, and when the current passes through the slag pool, Joule heat is generated to melt the consumable electrode, and the current flows in the directions of the electrode, slag pool, bottom water tank, power supply and the electrode, slag pool, crystallizer, power supply respectively; during the electroslag remelting process, since the temperature of the slag pool is higher than the temperature of the molten pool and ingot below, the temperature of the inner wall of the crystallizer close to the slag pool will be higher than the temperature of the inner wall of the crystallizer close to the molten pool and the ingot; the conductivity of the crystallizer close to the slag pool is higher than that close to the molten pool and the ingot, so that more current flows out through the crystallizer on the slag pool side; as the smelting process proceeds, the distance between the bottom water tank and the molten pool gradually increases, the temperature of the upper part of the bottom water tank gradually decreases, the conductivity of the highly doped silicon carbide wafer plate on the bottom water tank gradually decreases, and the current gradually decreases, which is conducive to forming a flat molten pool in the slag pool.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention arranges a highly doped silicon carbide wafer layer inside the crystallizer, so that more current flows out through the crystallizer on the slag pool side, thereby reducing losses and improving current utilization.

[0020] 2. The present invention arranges a highly doped silicon carbide wafer plate at the bottom of the bottom water tank. As the smelting process proceeds, the distance between the bottom water tank and the molten pool gradually increases, and the temperature of its upper part gradually decreases. The electrical conductivity of the highly doped silicon carbide wafer plate will gradually decrease, and the current will gradually decrease, which is conducive to forming a flat molten pool in the slag pool and improving the quality of the ingot.

[0021] 3. This invention leverages the gradual increase in electrical conductivity of silicon carbide wafers with increasing temperature and the upward solidification of the ingot during electroslag remelting to dynamically control current distribution and improve the uniformity of the solidification structure. Furthermore, the high melting point of silicon carbide wafers effectively protects the inner wall of the crystallizer from erosion by the high temperature of the ingot. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the internal structure of the present invention.

[0023] Figure 2 It is a structural schematic diagram of the present invention.

[0024] In the figure: 1-crystallizer water outlet, 2-inner wall, 3-water chamber, 4-highly doped silicon carbide wafer layer, 5-slag pool, 6-steel ingot, 7-outer wall of water chamber, 8-crystallizer water inlet, 9-crystallizer conductive column, 10-highly doped silicon carbide wafer plate, 11-bottom water tank water outlet, 12-bottom water tank conductive column, 13-bottom water tank water chamber, 14-bottom water tank water inlet, 15-molten pool. DETAILED DESCRIPTION

[0025] The present invention will be described in detail below with reference to the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0026] See Figure 1 、 Figure 2 A conductivity-adjustable electroslag remelting crystallizer comprises a crystallizer and a bottom water tank arranged at the bottom of the crystallizer. A highly doped silicon carbide wafer layer 4 is fixed to the inner wall 2 of the crystallizer. The highly doped silicon carbide wafer layer 4 is a straight cylindrical structure. A circular highly doped silicon carbide wafer plate 10 is fixed to the top of the bottom water tank. The bottom end of the highly doped silicon carbide wafer layer 4 rests on the highly doped silicon carbide wafer plate 10.

[0027] Among them, the inner wall 2 of the crystallizer is welded to the highly doped silicon carbide wafer layer 4. The highly doped silicon carbide wafer layer 4 and the highly doped silicon carbide wafer plate 10 are both doped with 6H-SIC silicon carbide wafers or 4H-SIC silicon carbide wafers, which have the characteristics of high temperature resistance and high thermal conductivity, and the conductivity of the silicon carbide wafers gradually increases with increasing temperature. 6H-SIC silicon carbide wafers are preferred because the melting point of 6H-SIC silicon carbide wafers is higher, which can better prevent the crystallizer from being corroded by the high temperature of the ingot. The highly doped silicon carbide wafer layer 4 and the highly doped silicon carbide wafer plate 10 are both doped with N-type, and the doping concentration range is 1×10 19 ~1×10 20 cm -3 .

[0028] The crystallizer and the bottom water tank are separated and are suitable for ingot-drawing electroslag furnaces. The crystallizer includes a water chamber 3, which is a straight cylindrical structure. The inner side of the water chamber 3 is welded and fixed to a highly doped silicon carbide wafer layer 4. A crystallizer water inlet 8 is provided at the lower part of the water chamber 3, and a crystallizer water outlet 1 is provided at the upper part, both of which are connected to the outer wall 7 of the water chamber of the crystallizer. The crystallizer water inlet 8 is arranged on one side of the water chamber 3, and the crystallizer water outlet 1 is arranged on the other side of the water chamber 3. The crystallizer water inlet 8 and the crystallizer water outlet 1 are both connected to the external pipeline through flanges, which can supply and drain water to the water chamber 3. A crystallizer conductive column 9 is fixed at the bottom of the water chamber 3. The crystallizer conductive column 9 is made of pure copper; the crystallizer conductive column 9 is connected to an external power supply.

[0029] The bottom of the water tank is equipped with a water inlet 14. A water outlet 11 is located on one side of the tank, providing water to and draining from the water chamber 13. A conductive column 12 is located on the other side of the tank. This column is made of pure copper and is connected to an external power source. Both the water inlet 14 and the water outlet 11 are connected to external piping via flanges.

[0030] The current flows in two directions: when the inner wall 2 of the crystallizer is conductive, the current flows from electrode to slag pool 5 to crystallizer and then to power supply. If the inner wall 2 of the crystallizer is non-conductive, the current flows from electrode to slag pool 5 to bottom water tank and then to power supply. When the electroslag remelting crystallizer with adjustable electrical conductivity is in operation, it utilizes the low electrical conductivity of highly doped silicon carbide wafers at room temperature and the positive correlation between electrical conductivity and temperature. A consumable electrode is inserted into the molten slag pool 5, and when current flows through the slag pool 5, Joule heat is generated, causing the electrode to melt. Based on the temperature changes of the slag pool during the smelting process, the highly doped silicon carbide wafer layer 4 adjusts its electrical conductivity, thereby controlling the direction of the current and adjusting the current density distribution. This effectively adjusts the temperature distribution of the slag pool 5, affecting the depth of the molten pool and, consequently, the quality of the ingot.

[0031] During the electroslag remelting process, the temperature of the slag pool 5 is higher than the temperature of the molten pool and the ingot below. Therefore, the temperature of the inner wall 2 of the crystallizer near the slag pool 5 will be higher than the temperature of the inner wall 2 of the crystallizer near the molten pool 15 and the steel ingot 6. Due to the characteristics of 6H-SIC, the electrical conductivity of the crystallizer near the molten pool 15 will also be higher than that near the slag pool 5 and the steel ingot 6, so that more current will flow out of the crystallizer through the slag pool 5 side, which will reduce losses and improve current utilization. Moreover, as the smelting process proceeds, the distance between the bottom water tank and the molten pool gradually increases, and the temperature of its upper part gradually decreases. The electrical conductivity of the highly doped silicon carbide wafer plate 10 welded on the bottom water tank will gradually decrease, and the current will gradually decrease, which is conducive to forming a flat molten pool 15 in the slag pool 5 and improving the quality of the ingot. The molten pool 15 is a metal molten pool, and the consumable electrode melts and drips in the slag pool 5, forming a metal molten pool 15 below the slag pool 5. The flatness of the metal molten pool 15 is more conducive to the directional solidification of the ingot and improves the quality of the ingot.

[0032] The present invention utilizes the property of silicon carbide wafers that their electrical conductivity gradually increases with temperature, and the fact that the steel ingot 6 solidifies from bottom to top during electroslag remelting, to dynamically control current distribution and improve the uniformity of the solidification structure. Furthermore, the relatively high melting point of silicon carbide wafers effectively protects the inner wall 2 of the crystallizer from erosion by the high temperature of the ingot. The present invention incorporates a highly doped silicon carbide wafer layer 4 inside the crystallizer, allowing more current to flow out of the crystallizer through the slag pool 5, thereby reducing losses and improving current utilization.

Claims

1. An electroslag remelting crystallizer with adjustable electrical conductivity, characterized in that: It includes a crystallizer and a bottom water tank arranged at the bottom of the crystallizer. The inner wall of the crystallizer is fixed with a highly doped silicon carbide wafer layer, and the highly doped silicon carbide wafer layer is a straight cylindrical structure. The top of the bottom water tank is fixed with a circular highly doped silicon carbide wafer plate, and the bottom end of the highly doped silicon carbide wafer layer rests on the highly doped silicon carbide wafer plate.

2. The electroslag remelting crystallizer with adjustable electrical conductivity according to claim 1, characterized in that: The inner wall of the crystallizer is welded to the highly doped silicon carbide wafer layer.

3. The electroslag remelting crystallizer with adjustable electrical conductivity according to claim 1, characterized in that: The highly doped silicon carbide wafer layer and the highly doped silicon carbide wafer plate are both doped with 6H-SIC silicon carbide wafers or 4H-SIC silicon carbide wafers.

4. The electroslag remelting crystallizer with adjustable electrical conductivity according to claim 1, characterized in that: The crystallizer comprises a water cavity which is a straight cylindrical structure. The inner side of the water cavity is fixed to the highly doped silicon carbide round crystal layer. The lower part of the water cavity is provided with a crystallizer water inlet, and the upper part is provided with a crystallizer water outlet.

5. The electroslag remelting crystallizer with adjustable electrical conductivity according to claim 4, characterized in that: A crystallizer conductive column is fixed at the bottom of the water chamber, and the crystallizer conductive column is made of pure copper; the crystallizer conductive column is connected to an external power supply.

6. The electroslag remelting crystallizer with adjustable electrical conductivity according to claim 4, characterized in that: The water inlet of the crystallizer is arranged on one side of the water cavity, and the water outlet of the crystallizer is arranged on the other side of the water cavity.

7. The electroslag remelting crystallizer with adjustable electrical conductivity according to claim 4, characterized in that: The water inlet and outlet of the crystallizer are both connected to the external pipeline through flanges.

8. The electroslag remelting crystallizer with adjustable electrical conductivity according to claim 1, characterized in that: A water inlet is provided at the bottom of the bottom water tank; a water outlet is provided on one side of the bottom water tank, and a conductive column is provided on the other side; the conductive column is made of pure copper and is connected to an external power supply.

9. The electroslag remelting crystallizer with adjustable electrical conductivity according to claim 8, characterized in that: The water inlet and outlet of the bottom water tank are both connected to the external pipeline through flanges.

10. The electroslag remelting mold with adjustable electrical conductivity according to claim 1, characterized in that: When the electroslag remelting crystallizer is performing electroslag remelting, the consumable electrode is inserted into the molten slag pool, and when the current passes through the slag pool, Joule heat is generated to melt the consumable electrode, and the current flows in the directions of the electrode, slag pool, bottom water tank, power supply and the electrode, slag pool, crystallizer, power supply respectively; during the electroslag remelting process, since the temperature of the slag pool is higher than the temperature of the molten pool and ingot below, the temperature of the inner wall of the crystallizer close to the slag pool will be higher than the temperature of the inner wall of the crystallizer close to the molten pool and the ingot; the conductivity of the crystallizer close to the slag pool is higher than that close to the molten pool and the ingot, so that more current flows out through the crystallizer on the slag pool side; as the smelting process proceeds, the distance between the bottom water tank and the molten pool gradually increases, the temperature of the upper part of the bottom water tank gradually decreases, the conductivity of the highly doped silicon carbide wafer plate on the bottom water tank gradually decreases, and the current gradually decreases, which is conducive to forming a flat molten pool in the slag pool.

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