Method and device for electroslag remelting by using composite consumable electrode

Abstract

The invention discloses a composite consumable electrode and a method and device for electroslag remelting by using the composite consumable electrode, and belongs to the technical field of electroslag remelting. The composite consumable electrode comprises a composite core rod and a consumable electrode outer layer which are arranged from inside to outside, wherein the composite core rod comprises a consumable electrode core layer and a slag charge layer which are arranged from inside to outside, and the slag charge layer forms an insulating layer between the consumable electrode core layer and the consumable electrode outer layer; the consumable electrode outer layer is used for being connected with one end of the short net, and current flows in from the consumable electrode outer layer, sequentially flows through the slag bath and the bottom water tank and then flows out from the short net to form a shallow flat metal molten pool. According to the scheme, the structure of the consumable electrode used for electroslag remelting is optimally designed, the consumable electrode is designed to be of a multi-layer composite structure, and the trend of a current loop in the electroslag remelting process of the consumable electrode is changed, so that a shallow flat metal molten pool is formed in the stable remelting stage, and the effect of optimizing the shape of the molten pool is achieved.

Description

Technical Field

[0001] This invention relates to the field of electroslag remelting technology, and more specifically, to a method and apparatus for electroslag remelting using a composite consumable electrode. Background Technology

[0002] Electroslag remelting, as a special metallurgical technology, plays an important role in the preparation of high-end metallic materials. However, electroslag remelting still faces several technical challenges in industrial applications, hindering further improvements in product quality. These challenges are as follows: (1) The metal droplets fall into the central region of the molten pool, resulting in a significant heat concentration in the region, which makes it easy to form a deeper molten pool. The morphology of a deeper molten pool will significantly affect the solidification process, promote the formation of coarse columnar crystals, and may cause compositional segregation, which will have an adverse effect on the solidification structure of the ingot.

[0003] (2) During the remelting process, as the slag skin continues to form and components such as calcium fluoride in the slag material volatilize, the total mass of the slag pool and its chemical composition (especially the fluoride content) will change significantly, which will cause the physicochemical properties of the remelted slag to deviate from the initial settings, thereby increasing the complexity of process control and making it difficult to guarantee the stability of the smelting process.

[0004] Solving the aforementioned technical problems and further improving the quality of electroslag ingots has always been an important research topic for those skilled in the art. In existing electroslag remelting processes, various technical means can be employed to reduce the molten pool depth and maintain stable slag pool performance. This invention proposes a novel method for electroslag remelting using composite consumable electrodes to solve the aforementioned technical problems. Summary of the Invention

[0005] 1. Technical problems to be solved This invention provides a method and apparatus for electroslag remelting using a composite consumable electrode. This method optimizes the structure of the consumable electrode used in electroslag remelting by designing it as a multi-layered composite structure and altering the current loop direction during the electroslag remelting process. This results in the formation of a shallow, flat molten metal pool during the stable remelting stage, thus optimizing the pool morphology. Simultaneously, the slag layer within the composite consumable electrode continuously replenishes the slag pool, ensuring sustained slag stability. Both of these aspects effectively improve the quality of the electroslag ingot.

[0006] 2. Technical solutions adopted To achieve the above objectives, the technical solution provided by the present invention is as follows: The first aspect of the present invention provides a composite consumable electrode, comprising a composite core rod and a consumable electrode outer layer arranged from the inside out; the composite core rod comprises a consumable electrode core layer and a slag layer arranged from the inside out, the slag layer forming an insulating layer between the consumable electrode core layer and the consumable electrode outer layer; the consumable electrode outer layer is used to connect to a short grid, and current flows in from the consumable electrode outer layer, flows sequentially through a slag pool and a bottom water tank, and then flows out from the short grid to form a shallow, flat molten metal pool.

[0007] It should be noted that this invention incorporates a slag layer inside the composite consumable electrode. During remelting, the slag melts along with the electrode, utilizing the heat of the slag pool to continuously melt the slag, achieving continuous and stable slag replenishment. This effectively counteracts fluctuations in slag pool composition caused by slag skin formation and component volatilization, thereby maintaining the stability of its physicochemical properties. Compared to adding slag externally from the top of the crystallizer, this built-in slag replenishment method avoids sudden temperature changes and process disturbances in the slag pool caused by slag addition, significantly improving the stability of the remelting process and ensuring the consistency of electroslag ingot solidification quality.

[0008] More importantly, this slag layer forms an insulating layer between the outer electrode layer and the core layer. Combined with a corresponding short-grid connection design, this ensures that current is primarily introduced from the outer electrode layer, with very little or no current in the core layer. This concentrates the heating zone on the outer electrode layer and disperses it to the edge of the crystallizer, while the core layer mainly melts by absorbing heat from the center of the slag pool, further reducing the core temperature. In summary, this structural design not only achieves stable slag replenishment but also effectively alleviates heat concentration in the center of the molten pool, promoting the formation of a shallow, flat molten pool, suppressing the growth of coarse columnar crystals and compositional segregation, thereby improving the solidification quality of the electroslag ingot.

[0009] Furthermore, the ratio of the cross-sectional area of ​​the consumable electrode core layer to the cross-sectional area of ​​the composite consumable electrode outer layer is 1:3 to 9. The cross-section of the composite consumable electrode outer layer is annular, and its cross-sectional area is calculated based on the area occupied by the annulus. If the diameter of the consumable electrode core layer is too large, the slag pool will heat it to melt the core layer, resulting in a lower overall slag temperature and reduced melting efficiency and remelting rate. Conversely, if the diameter of the consumable electrode core layer is too small, the thermal state of the slag pool core cannot be effectively regulated. Therefore, controlling the cross-sectional area ratio of the consumable electrode core layer to the cross-sectional area of ​​the composite consumable electrode outer layer between 1:3 and 1:9 effectively disperses the heat in the slag pool to optimize the temperature field distribution while ensuring good melting efficiency and stability of the remelting process.

[0010] Furthermore, the raw materials for the slag layer include the following components by mass percentage: 70% to 90% slag material of the same remelting slag system and 10% to 30% fluorite. The raw materials are pre-melted, cooled, and then crushed into particles with a diameter of 0.5 to 1 mm. The mass of the slag material used in the slag layer accounts for 5% to 10% of the total slag mass.

[0011] Furthermore, the composite mandrel also includes an aluminum foil layer, which is placed between the slag layer and the consumable electrode core layer. The aluminum foil layer is continuously melted by the slag pool temperature to replenish the deoxidizer in the slag pool. The total mass of the aluminum foil layer is calculated based on adding 0.6~1.5 kg of aluminum foil per ton of molten steel.

[0012] During the electroslag remelting stage, the aluminum foil layer continuously and uniformly releases aluminum into the slag pool as the composite consumable electrode melts, achieving continuous deoxidation of the molten pool. This method not only significantly reduces the burn-off of easily oxidized elements and lowers the oxide inclusion content in the steel, but also overcomes the problem of uneven deoxidation caused by traditional intermittent deoxidation or top feeding, thereby ensuring a higher and more consistent cleanliness level along the longitudinal direction of the electroslag ingot.

[0013] In the preparation process of composite consumable electrode, generally speaking, a composite core rod is prepared in the composite consumable electrode, and then the outer layer of the consumable electrode is formed by casting on the outside of the composite core rod. The aluminum foil layer is placed on the inner side of the slag layer away from the outer layer of the consumable electrode. The slag layer plays an insulating role, effectively blocking the heat transfer from the external high-temperature molten steel to the aluminum foil layer, thereby preventing the aluminum foil layer from melting due to heat.

[0014] Furthermore, the distance h from the bottom of the outer layer of the consumable electrode to below the bottom of the composite core rod is used to form a single-layer consumable electrode segment with a height of h and an outer diameter identical to that of the outer layer of the consumable electrode at the bottom of the composite core rod. The single-layer consumable electrode segment at the bottom of this composite consumable electrode facilitates the flow of current across the entire electrode cross-section into the slag pool during the initial remelting stage, rapidly increasing the temperature of the slag pool and facilitating a quicker entry into a stable remelting state. Generally, a small section of the bottom of the electroslag ingot obtained through electroslag remelting is removed, and the height of the single-layer consumable electrode segment at the bottom is typically designed with reference to the height of this removed section.

[0015] Furthermore, the composite mandrel also includes an iron sheet layer, which is disposed outside the slag layer, and the thickness of the iron sheet layer is 1~2mm.

[0016] The iron sheet layer serves a dual function: firstly, it creates a stable space for the slag layer outside the consumable electrode core layer; secondly, it utilizes the melting point gradient relationship where the iron sheet layer's melting point is higher than that of the cast steel, and the molten steel's melting point is higher than that of the slag. In the conventional casting process for composite consumable electrodes, this iron sheet layer effectively blocks direct heat transfer between the cast steel and the slag layer, and prevents molten steel from penetrating into the consumable electrode core layer due to the melting of the slag layer. This effectively avoids conductive paths formed between the consumable electrode core layer and the outer layer due to molten steel penetration, ensuring the electrical insulation performance of the composite consumable electrode design.

[0017] The second aspect of the present invention provides a method for electroslag remelting using the above-mentioned composite consumable electrode, specifically including the following steps: S1, slag arc initiation, specifically, using a graphite electrode to slag, with a slag initiation time of 20 min to 80 min; S2, stable remelting stage; removing the graphite electrode and sending the composite consumable electrode into a crystallizer, using a power supply mode of 30 to 50V and 5000 to 2000A; this step uses a weighing system to monitor the melting quality of the composite consumable electrode; S3, feeding stage; S4, electroslag ingot demolding.

[0018] Furthermore, after the bottom h of the composite consumable electrode is completely melted, the control method is selected as voltage swing or resistance swing, as follows: when the resistivity of the slag pool is ≥ 0.40 Ω·cm, voltage swing control is adopted, and the voltage swing amplitude is 1.5~3.0 V; when the resistivity of the slag pool is <0.40 Ω·cm, resistance swing control is adopted, and the swing amplitude is 0.2~0.7 mΩ.

[0019] Generally, in the initial stage of remelting of composite consumable electrodes, i.e., during the melting process at the bottom height h, the internal current and voltage are unstable and fluctuate greatly. At this time, it is not suitable to effectively control the oscillation. That is, the melting process of the bottom section at height h is unstable, so the corresponding electroslag ingot is also cut off. Only after the remelting enters a stable state can the oscillation control of the remelting process be easily implemented.

[0020] This invention intelligently selects voltage or resistance swing control based on the compositional changes in the slag pool during the remelting process to precisely and stably stabilize the insertion depth of the composite consumable electrode into the slag pool. This control method can synergize with the formed shallow, flat molten metal pool, improving the precision control over the morphology of the molten metal pool and overcoming the defect of uncontrolled insertion depth caused by neglecting the performance changes of the slag pool in a single control method. This further improves the high uniformity of the resulting electroslag ingot microstructure.

[0021] Furthermore, the process also includes the preparation of the composite consumable electrode prior to electroslag remelting, comprising the following steps: first, preparing a composite mandrel by placing the composite mandrel in a steel ingot mold, with the distance h between its bottom end and the inner bottom end of the steel ingot mold being 5-10 cm; then, injecting molten steel into the steel ingot mold by bottom injection to form an outer layer of consumable electrode covering the composite mandrel, resulting in a composite consumable electrode with a height difference h between the bottom end of the composite mandrel and the bottom end of the outer layer of the consumable electrode. The design of this gap h also facilitates the flow of molten steel around the periphery of the composite mandrel during casting. By designing the composite structure of the composite consumable electrode, its preparation is facilitated.

[0022] A third aspect of the present invention provides an apparatus for electroslag remelting using the aforementioned composite consumable electrode. The apparatus includes a composite consumable electrode, a short grid, a crystallizer, a transformer, and a bottom water tank. The composite consumable electrode includes a composite core rod and an outer layer of consumable electrode arranged from the inside out. The composite core rod includes a core layer of consumable electrode and an insulating layer arranged from the inside out. The transformer is connected to the short grid for supplying power to the short grid. One end of the short grid is connected to the outer layer of the consumable electrode, and the other end is connected to the bottom water tank to form a current loop for electroslag remelting. The current flows from the short grid into the outer layer of the consumable electrode through the transformer, flows sequentially through the slag pool and the bottom water tank, and then flows out from the short grid back to the transformer.

[0023] Compared with the prior art, the technical solution provided by this invention has the following advantages: (1) The present invention optimizes the structure of the composite consumable electrode. Specifically, the composite core rod of the composite consumable electrode contains a slag layer, which forms an insulating layer between the core layer and the outer layer of the consumable electrode. Simultaneously, during the electroslag remelting process, one end of the short mesh is connected to the outer layer of the consumable electrode, and the other end is connected to the water tank to form the current circuit required for electroslag remelting. During the remelting process, the slag layer continuously replenishes the slag pool, thereby maintaining the stability of the physicochemical properties of the slag pool. With the design of the current circuit, the heating zone of this composite consumable electrode is mainly concentrated on the outer layer of the consumable electrode, achieving dispersion of the heating zone near the edge of the crystallizer. The composite core rod mainly melts by absorbing heat from the center of the slag pool, further reducing the core temperature.

[0024] (2) The present invention further optimizes the design of the composite mandrel. Specifically, an internal aluminum foil layer is set in the composite consumable electrode, so that aluminum is gradually released during the electroslag remelting process by continuously melting at the slag pool temperature, and deoxidizer is continuously replenished to the slag pool to achieve continuous deoxidation of the slag pool. This setting can not only effectively reduce the burn-off of easily oxidized elements and reduce the oxide inclusion content, but also overcome the defects of uneven deoxidation caused by traditional intermittent deoxidation or continuous top feeding, thereby ensuring that the obtained electroslag ingot has a higher and more consistent cleanliness level along the longitudinal direction.

[0025] (3) The present invention further optimizes the design of the composite mandrel. Specifically, the iron sheet layer is set outside the slag layer, and the thickness of the iron sheet layer is 1~2mm. The setting of the iron sheet layer forms a space for the slag layer outside the consumable electrode core layer. On the other hand, during the preparation of the composite consumable electrode, it helps to reduce the direct heat transfer between the injected molten steel and the slag layer, and effectively avoids the molten steel from penetrating into the consumable electrode core layer due to the melting of the slag layer, thereby preventing the consumable electrode core layer from conducting electricity with the consumable electrode outer layer.

[0026] (4) The present invention further optimizes the current control method during the remelting process. Specifically, according to the resistivity of the slag pool, the control method is selected as voltage swing or resistance swing to accurately stabilize the insertion depth of the composite consumable electrode into the slag pool. This overcomes the defect of the single control method causing the insertion depth to run out of control due to ignoring the performance changes of the slag pool, thereby further improving the high uniformity of the resulting electroslag ingot structure. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the electroslag remelting apparatus in an embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram of the overall structure of the composite consumable electrode in an embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram of the composite mandrel in an embodiment of the present invention.

[0030] Figure 4 This is a schematic diagram of the casting process of the composite consumable electrode in an embodiment of the present invention.

[0031] Figure 5 This is a schematic diagram of the test points taken along the longitudinal direction when performing performance testing on the obtained electroslag ingot according to the present invention.

[0032] Figure 6 This is a schematic diagram of the test points taken along the transverse direction when performing performance testing on the obtained electroslag ingot according to the present invention.

[0033] Label Explanation: 1. Composite consumable electrode; 101. Outer layer of consumable electrode; 102. Core layer of consumable electrode; 103. Aluminum foil layer; 104. Slag layer; 105. Sheet metal layer; 2. Crystallizer; 3. Bottom water tank; 4. Short network; 5. Transformer; 6. Slag pit; 7. Steel ingot mold; 8. Injection tube. Detailed Implementation

[0034] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings and embodiments.

[0035] Example 1 This embodiment provides a method for electroslag remelting using a composite consumable electrode. The consumable electrode used in the electroslag remelting includes a composite core rod arranged from the inside out and a consumable electrode outer layer 101. The composite core rod includes a consumable electrode core layer 102, an aluminum foil layer 103, a slag layer 104, and an iron sheet layer 105 arranged sequentially from the inside out. The consumable electrode outer layer 101 and the consumable electrode core layer 102 are made of the same material, both cast from molten steel. The Al element in the cast steel used for the consumable electrode outer layer 101 and the consumable electrode core layer 102 is 0.505%.

[0036] The preparation steps of this electroslag remelting method are as follows: (a) Preparation of composite mandrel First, a consumable electrode core layer 102 is cast. Then, an aluminum foil layer 103 is wrapped around the outside of the consumable electrode core layer 102. After that, an iron sheet layer 105 is placed outside the aluminum foil layer 103, and there is a gap between the iron sheet layer 105 and the aluminum foil layer 103 to form a cavity for receiving slag layer 104.

[0037] The raw material of the slag layer 104 is pre-melted, cooled, and then crushed into particles with a diameter of 0.5~1mm. The crushed slag particles are tightly compacted into the cavity between the sheet metal layer 105 and the aluminum foil layer 103.

[0038] The raw materials of the slag layer 104 include the following components by mass percentage: 80% slag of the same type as the remelted slag system and 20% fluorite, with CaF2 ≥ 98.0% in the fluorite; the slag used in the slag layer 104 accounts for 7% of the total slag mass, where the total slag mass is the sum of the amount of slag used in the slag layer 104 and the amount of slag melted during the arc initiation stage of the liquid slag.

[0039] The thickness of the slag layer 104 is calculated using Formula 1, as follows:

[0040] in, X1 represents the thickness of the slag layer 104, in meters (m); G represents the mass of slag melted during the arc initiation stage of the liquid slag, in kilograms (kg); X1 represents the cross-sectional area of ​​the consumable electrode core layer 102, in square meters (m²). 2 X2 represents the cross-sectional area of ​​the outer layer 101 of the consumable electrode, in meters (m²). 2 ; ρ This indicates the density of the slag layer 104, in kg / m³. 3 V represents the remelting rate, in kg / min; T represents the total remelting time, in min; B is the thickness coefficient of the slag layer 104, with a value of 0.05~0.1. Based on the mass ratio of slag used in the slag layer 104, B is 0.07 in this embodiment.

[0041] The total mass of aluminum foil layer 103 is calculated based on adding 1.1 kg of aluminum foil per ton of molten steel. The thickness of aluminum foil layer 103 is calculated using formula (2), as follows:

[0042] in, X1 represents the thickness of the aluminum foil layer 103, in meters (m); X2 represents the cross-sectional area of ​​the consumable electrode core layer 102, in meters (m²). 2 X2 represents the cross-sectional area of ​​the outer layer 101 of the consumable electrode, in meters (m²). 2 A is the thickness coefficient of aluminum foil layer 103, and its value ranges from 4.68 to 11.70.

[0043] Based on the calculation of adding 1.1 kg of aluminum foil per ton of molten steel, the value of A in this embodiment is 8.58.

[0044] The sheet metal layer 105 is made of pure sheet metal, and its thickness can be selected from 1 to 2 mm. In this embodiment, it is specifically selected as 1.5 mm, and the Fe content is ≥99.0%. The aluminum foil layer 103 is made of aluminum foil, and the Al content is ≥99.5%.

[0045] (II) Preparation of composite consumable electrode The prepared composite mandrel is placed in a steel ingot mold 7. The bottom of the steel ingot mold 7 is connected to the bottom of the central injection pipe 8. Molten steel is injected into the central injection pipe 8. Molten steel is injected into the steel ingot mold 7 by bottom injection of molten metal to form a consumable electrode outer layer 101 covering the outside of the composite mandrel. The distance between the bottom end of the composite mandrel and the bottom end of the inner side of the steel ingot mold 7 is... h The preferred spacing is 5-10cm.

[0046] The composite consumable electrode prepared by the above steps has a cross-sectional area ratio of 1:6 between the core layer 102 and the outer layer 101 of the composite consumable electrode.

[0047] (iii) Performing electroslag remelting The apparatus used for electroslag remelting includes the composite consumable electrode prepared above, a short grid 4, a crystallizer 2, a transformer 5, and a bottom water tank 3. (Reference) Figure 1 As shown, in the stable remelting stage, transformer 5 is connected to short grid 4 to supply power to short grid 4. One end of short grid 4 is connected to the outer layer 101 of consumable electrode, and the other end is connected to bottom water tank 3 to form a current loop for electroslag remelting. The current flows from short grid 4 into the outer layer 101 of consumable electrode through transformer 5, flows through slag pool 6 and bottom water tank 3 in sequence, and then flows out from short grid 4 to transformer 5.

[0048] The electroslag remelting process specifically includes the following steps: S1, Liquid slag arc initiation, wherein graphite electrode is used for slag formation, and the slag formation time is 60 min; S2. In the stable remelting stage, the graphite electrode is removed, and the composite consumable electrode is placed into the crystallizer 8. Power is supplied using a voltage of 30-50V and a current of 5000-2000A. This step uses a weighing system to monitor the melting quality of the composite consumable electrode. When the lower part of the composite consumable electrode... h After complete melting, the control method is selected as either voltage swing or resistance swing, as follows: when the resistivity of the slag pool is ≥ 0.40 Ω·cm, voltage swing control is used, with a voltage swing amplitude of 1.5~3.0 V; when the resistivity of the slag pool is <0.40 Ω·cm, resistance swing control is used, with a swing amplitude of 0.2~0.7 mΩ. S3, Compensation and Shrinkage Stage; S4. Demolding of electroslag ingots.

[0049] The oxide inclusions of the electroslag ingots prepared in Example 1 were rated as follows: Class A, Grade 0; Class B, Grade 0.5; Class C, Grade 0; Class D, Grade 0.5; and Class DS, Grade 0.5.

[0050] Comparative Example 1 This comparative example provides a method for electroslag remelting, in which the consumable electrode is integrally cast, i.e., a single-layer consumable electrode, and its dimensions are the same as the overall dimensions of the composite consumable electrode in Example 1. During the stable remelting stage, only voltage oscillation is used, with a voltage oscillation amplitude of 1.5~3.0 V; the remaining operations are basically the same.

[0051] Comparative Example 2 This comparative example provides a method for electroslag remelting, in which the consumable electrode is integrally cast, i.e., a single-layer consumable electrode, and its dimensions are the same as the overall dimensions of the composite consumable electrode in Example 1. During the stable remelting stage, only resistance oscillation is used, with an oscillation amplitude of 0.2~0.7 mΩ; the remaining operations are basically the same.

[0052] Comparative Example 3 This comparative example provides a method for electroslag remelting using a composite consumable electrode. The difference from Example 1 is that the composite consumable electrode used includes a composite core rod arranged from the inside out and a consumable electrode outer layer 101. The composite core rod includes a consumable electrode core layer 102, an aluminum foil layer 103, and an iron sheet layer 105 arranged sequentially from the inside out. The preparation process of this composite consumable electrode is basically similar to that of Example 1, except that a slag layer 104 is not provided; the rest of the operations are basically the same.

[0053] Performance testing For the electroslag ingots obtained in Example 1 and Comparative Examples 1-3, after removing the slag skin, a point on the outer edge along the longitudinal direction was selected as a sampling point for elemental content testing. The selection of the sampling point was based on the following references. Figure 5 As shown, tests were conducted at heights of 1 / 6, 2 / 6, 3 / 6, 4 / 6, and 5 / 6 of the obtained electroslag ingot. Taking the Al element in the electroslag ingot as an example, the specific test results are detailed in Table 1.

[0054] After removing the slag skin, elemental content was tested on cross-sections at 1 / 6 and 5 / 6 heights of the resulting electroslag ingot. The sampling points were selected based on... Figure 6 As shown, at 1 / 6 of the height, for cross-section A, the center of the cross-section is called a4, and the test points a3 and a4 are selected. 2、 The distances between a1 and the center a4 are 1 / 4R, 2 / 4R, and 3 / 4R respectively. Taking Al in electroslag ingots as an example, the specific test results are detailed in Table 2.

[0055]

[0056]

[0057] As can be seen from Table 1, the Al content in the electroslag ingot obtained in Example 1 is between 0.506% and 0.510%, with a variation range of 0.004%. Compared with Comparative Examples 1-3, the variation range of Al is smaller and closer to the Al content in the outer layer 101 and the core layer 102 of the consumable electrode in the composite consumable electrode. The longitudinal uniformity of the obtained electroslag ingot is significantly improved.

[0058] Table 2 shows that in the cross-section of the electroslag ingot obtained in Example 1 at 1 / 6 height, the Al content ranges from 0.504% to 0.508%, with a variation range of 0.004%. In the cross-section of the electroslag ingot obtained in Example 1 at 5 / 6 height, the Al content ranges from 0.506% to 0.512%, with a variation range of 0.006%. Compared with Comparative Examples 1-3, the Al content in the Examples is smaller in range and closer to the Al content in the outer layer 101 and the core layer 102 of the consumable electrode in the composite consumable electrode.

[0059] Example 2 This embodiment provides a method for electroslag remelting using a composite consumable electrode. The difference between this method and the composite consumable electrode used in Embodiment 1 is that the slag material of the slag layer 104 includes the following components in terms of mass percentage: 70% remelting slag system and 30% fluorite; the mass of the slag material used in the slag layer 104 accounts for 10% of the total slag material. Accordingly, the value of B in formula (1) is 0.1.

[0060] The total mass of aluminum foil layer 103 is calculated based on adding 0.6 kg of aluminum foil per ton of molten steel. Accordingly, the value of A in formula (2) is 4.68.

[0061] The ratio of the cross-sectional area of ​​the consumable electrode core layer 102 to that of the composite consumable electrode outer layer 101 is 1:3.

[0062] The difference between this embodiment and Embodiment 1 in the electroslag remelting process is that the slag-forming time in S1 is selected as 20 min.

[0063] The longitudinal uniformity of Al element in the electroslag ingot obtained in this embodiment is similar to that of the electroslag ingot obtained in Example 1. The inclusion rating of the obtained electroslag ingot is: Class A 0, Class B 0.5, Class C 0.5, Class D 0.5, and Class DS 0.5.

[0064] Example 3 This embodiment provides a method for electroslag remelting using a composite consumable electrode. The difference between the composite consumable electrode used in the other embodiments is that the slag material of the slag layer 104 includes the following components in terms of mass percentage: 90% remelting slag system and 10% fluorite; the mass of the slag material used in the slag layer 104 accounts for 5% of the total slag material, and correspondingly, the value of B in formula (1) is 0.05.

[0065] The total mass of aluminum foil layer 103 is calculated based on adding 1.5 kg of aluminum foil per ton of molten steel. Accordingly, the value of A in formula (2) is 11.7.

[0066] The ratio of the cross-sectional area of ​​the consumable electrode core layer 102 to that of the composite consumable electrode outer layer 101 is 1:9.

[0067] The difference between this embodiment and Embodiment 1 in the electroslag remelting process is that the slag-forming time in S1 is selected as 80 min.

[0068] The longitudinal uniformity of Al element in the electroslag ingot obtained in this embodiment is similar to that of the electroslag ingot obtained in Example 1. The inclusion rating of the obtained electroslag ingot is: Class A 0, Class B 0.5, Class C 0.5, Class D 0.5, and Class DS 0.5.

Claims

1. A composite consumable electrode, characterized in that, It includes a composite core rod arranged from the inside out and a consumable electrode outer layer (101); the composite core rod includes a consumable electrode core layer (102) and a slag layer (104) arranged from the inside out, and the slag layer (104) forms an insulating layer between the consumable electrode core layer (102) and the consumable electrode outer layer (101); The consumable electrode outer layer (101) is used to connect with the short mesh (4). Current flows in from the consumable electrode outer layer (101), flows through the slag pool (6) and the bottom water tank (3) in sequence, and then flows out from the short mesh (4) to form a shallow flat metal molten pool.

2. The composite consumable electrode according to claim 1, characterized in that, The ratio of the cross-sectional area of ​​the consumable electrode core layer (102) to the consumable electrode outer layer (101) is 1:3~9.

3. The composite consumable electrode according to claim 1, characterized in that, The raw materials of the slag layer (104) include the following components by mass percentage: 70%~90% slag material of the same remelting slag system and 10%~30% fluorite. The raw materials are particles with a diameter of 0.5~1mm that have been pre-melted, cooled and crushed. The slag material used in the slag layer (104) accounts for 5~10% of the total slag material mass.

4. The composite consumable electrode according to claim 1, characterized in that, The composite core rod also includes an aluminum foil layer (103). The aluminum foil layer (103) is disposed between the slag layer (104) and the consumable electrode core layer (102). The aluminum foil layer (103) is continuously melted by the temperature of the slag pool to replenish the deoxidizer in the slag pool. The mass of the aluminum foil layer (103) is calculated based on the amount of aluminum foil added per ton of molten steel, which is 0.6~1.5 kg.

5. The composite consumable electrode according to any one of claims 1-4, characterized in that, The distance from the bottom of the consumable electrode outer layer (101) to the bottom of the composite core rod is h, which is used to form a single-layer consumable electrode segment with a height of h and an outer diameter that is the same as the outer diameter of the consumable electrode outer layer (101) at the bottom of the composite core rod.

6. The composite consumable electrode according to claim 5, characterized in that, The composite mandrel also includes an iron sheet layer (105), which is disposed outside the slag layer (104) and has a thickness of 1~2mm.

7. A method for electroslag remelting using the composite consumable electrode as described in claim 5, characterized in that, Specifically, the steps include the following: S1. Liquid slag arc initiation, specifically, using graphite electrodes to slag, with a slag initiation time of 20min~80min; S2, Stable remelting stage; The composite consumable electrode is fed into the crystallizer (8) and powered by a power supply mode of 30~50V and 5000~2000A; The melting quality of the composite consumable electrode is monitored by a weighing system; S3, Compensation and Shrinkage Stage; S4. Demolding of electroslag ingots.

8. The method for electroslag remelting using a composite consumable electrode according to claim 7, characterized in that, After the bottom h of the composite consumable electrode is completely melted, the control method is selected as voltage swing or resistance swing, as follows: when the resistivity of the slag pool is ≥ 0.40 Ω·cm, voltage swing control is adopted, and the voltage swing amplitude is 1.5~3.0 V; when the resistivity of the slag pool is < 0.40 Ω·cm, resistance swing control is adopted, and the swing amplitude is 0.2~0.7 mΩ.

9. The method for electroslag remelting using a composite consumable electrode according to claim 7, characterized in that, It also includes the preparation of the composite consumable electrode prior to electroslag remelting, comprising the following steps: First, the composite core rod is prepared. The composite core rod is placed in the steel ingot mold (7), and the distance h between the bottom end and the inner bottom end of the steel ingot mold (7) is 5~10cm. Molten steel is injected into the steel ingot mold (7) by bottom injection to form a consumable electrode outer layer (101) covering the outside of the composite core rod, so as to obtain a composite consumable electrode with the bottom end of the composite core rod higher than the bottom end of the consumable electrode outer layer (101) and the height difference is h.

10. An apparatus for electroslag remelting using the composite consumable electrode according to any one of claims 1-5, characterized in that, The device includes a composite consumable electrode, a short grid (4), a crystallizer (2), a transformer (5), and a bottom water tank (3), wherein: The transformer (5) is connected to the short network (4) and is used to supply power to the short network (4); One end of the short mesh (4) is connected to the outer layer (101) of the consumable electrode, and the other end is connected to the bottom water tank (3) to form a current loop for electroslag remelting. The current flows from the short mesh (4) into the outer layer (101) of the consumable electrode through the transformer (5), flows through the slag pool (6) and the bottom water tank (3) in sequence, and then flows out from the short mesh (4) to the transformer (5).

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