Single-support-arm large-tonnage electroslag ingot feeding method

Abstract

The invention discloses a single-support-arm large-tonnage electroslag ingot feeding method which comprises the following steps: welding an electroslag dummy electrode at a nozzle end of an electroslag electrode, mounting the electroslag electrode on an electroslag furnace, supplying power to the electroslag furnace, and setting the melting speed to be 0.9 D / h kg / min in a steady state process; when the residual weight of the electroslag electrode is 1000kg, entering a feeding stage, melting the electroslag electrode, filling the molten electroslag electrode into a slag bath, feeding a shrinkage cavity, and reducing the melting speed by adopting a power reducing method so as to reduce the shrinkage cavity of an electroslag ingot; when the electroslag electrode is smelted to a diameter reduction step L, the melting speed and the voltage are immediately reduced, so that the electroslag electrode slowly melts the diameter reduction part; and when the electroslag electrode smelting residue is 30-50 mm, the melting speed and the voltage are reduced again, the electroslag electrode is made to stop melting, heat preservation is conducted for 30 min or above, and then power outage is conducted. By reducing the local diameter of the electrode nozzle position, the metal molten pool is directly reduced in the later period of feeding to achieve effective feeding, after the electrode diameter is reduced, the heat source area of the molten pool is reduced, and feeding is more stable.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and more particularly to a single-arm large-tonnage electroslag ingot shrinkage feeding method. Background Art

[0002] Electroslag remelting smelting belongs to secondary remelting, which can improve the quality of internal inclusions. It is carried out in a water-cooled copper crystallizer. As the smelting progresses, the molten steel near the inner wall of the crystallizer solidifies first, and the molten steel in the center solidifies slowly. The solidification and shrinkage of the molten steel will eventually form a central shrinkage cavity.

[0003] The diameter of the single-arm large-tonnage electroslag ingot is Ф1120~1320mm, the shrinkage compensation effect is poor, and the utilization rate of the electroslag ingot is low.

[0004] The diameter of the electrodes used for electroslag remelting in traditional single-arm electroslag furnaces is almost the same throughout their length. In this case, continuous decreasing power compensation or intermittent power outage compensation is generally adopted.

[0005] Continuous decreasing power compensation mainly involves gradually reducing the current and voltage. Due to the continuous replenishment of molten steel, the top shrinkage holes can be continuously filled, thus achieving the purpose of compensation.

[0006] Intermittent power outage compensation mainly adopts an intermittent power supply method of power outage for a certain period of time → reduce the current and then supply power again → power outage for a certain period of time → reduce the current and then supply power again → power outage again → power supply again.

[0007] Continuously decreasing power feeding, since the diameter of the electrode is almost the same throughout its length, although the input power decreases, the reduction in current and voltage will lead to unstable control of the feeding process. The slag temperature drops too much, resulting in the electrode being unable to melt or the melted amount being insufficient to fill the shrinkage cavity, causing looseness and shrinkage cavities, and a low ingot yield rate.

[0008] The intermittent power outage method, due to the continuous power outage and supply, causes large temperature fluctuations in the slag pool, and the slag skin is easily broken, resulting in slag flow and even steel flow, which destroys the continuity of shrinkage feeding and poor shrinkage feeding quality.

[0009] The above two shrinkage-feeding methods have poor shrinkage-feeding effects for the production of single-arm large-tonnage electroslag ingots, and the shrinkage hole depth reaches more than 200mm. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide a single-arm large-tonnage electroslag ingot feeding method, which can quickly reduce the depth of the molten pool, reduce the heat of the molten pool, and make the feeding more stable.

[0011] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows.

[0012] A single-arm large-tonnage electroslag ingot feeding method comprises the following steps:

[0013] A. Weld the electroslag dummy electrode to the nozzle end of the electroslag electrode, install the electroslag electrode on the electroslag furnace, supply power to the electroslag furnace, and set the melting rate to 0.9D / h kg / min during the steady state process, where D is the diameter of the electroslag ingot;

[0014] B. When the remaining weight of the electroslag electrode is 1000kg, it enters the shrinkage feeding stage. The electroslag electrode is melted and filled into the slag pool to feed the shrinkage holes. First, the power is reduced to reduce the melting speed to reduce the shrinkage holes of the electroslag ingot;

[0015] C. When the electroslag electrode is smelted to the reduced diameter step L, the melting speed and voltage are immediately reduced to allow the electroslag electrode to slowly melt the reduced diameter part;

[0016] D. When the electroslag electrode has 30 to 50 mm of smelting remaining, reduce the melting rate and voltage again to stop melting the electroslag electrode and keep it warm for more than 30 minutes, then turn off the power.

[0017] To further optimize the technical solution, in step B, after shrinkage compensation, the melting rate is reduced to 1 / 2 to 1 / 3 of the normal smelting melting rate.

[0018] To further optimize the technical solution, in step C, the melting rate is set to 10% to 20% of the normal melting rate, and the voltage is set to 70% to 80% of the normal smelting voltage.

[0019] To further optimize the technical solution, in step D, the melting rate is further reduced to 0.5-1.0 kg / min, and the voltage is set to 40%-50% of the normal smelting voltage.

[0020] Due to the adoption of the above technical scheme, the technical progress achieved by the present invention is as follows.

[0021] The present invention provides a single-arm large-tonnage electroslag ingot feeding method, which reduces the local diameter of the electroslag electrode water inlet position so that the metal molten pool can be directly reduced in the later stage of feeding to achieve effective feeding. After the diameter of the electroslag electrode is reduced, the heat source area of ​​the molten pool is reduced, the feeding is more stable, and the shrinkage hole depth is controlled within 80 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the present invention;

[0023] Figure 2 It is a schematic diagram of the structure of the electroslag electrode of the present invention;

[0024] Figure 3 It is a schematic diagram of the enlarged structure of the electrode water inlet end in the present invention.

[0025] Among them: 1. electroslag false electrode, 2. electroslag electrode, 3. slag pool, 4. molten pool, 5. electroslag ingot, 6. nozzle end. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] A single-arm large-tonnage electroslag ingot feeding method, combined with Figures 1 to 3 As shown, the electroslag electrode 2 is extended into the slag pool 3 for shrinkage compensation, and the nozzle end 6 of the electroslag electrode 2 is partially shrunk to 55-65% of the normal diameter. The height L is determined according to the actual appearance pit of the electroslag ingot 5. The shrinkage compensation method of the electroslag ingot includes the following steps:

[0028] A. Weld the electroslag dummy electrode 1 to the nozzle end 6 of the electroslag electrode 2, install the electroslag electrode on the electroslag furnace, and supply power to the electroslag furnace. During the steady-state process, the melting rate is set to 0.9D / h, where D is the diameter of the electroslag ingot 5, and the voltage is set to 45V. For example, if the diameter of the electroslag ingot is Ф1320mm, then the melting rate is 0.9*1320 / 60=19.8kg / min.

[0029] B. When the remaining weight of the electroslag electrode 2 is 1000kg, it enters the shrinkage feeding stage. The electroslag electrode 2 is melted and filled into the slag pool 3 to feed the shrinkage holes. After feeding, the melting rate is reduced to 1 / 2 to 1 / 3 of the normal smelting melting rate. The power reduction method is first used to reduce the melting rate to reduce the shrinkage holes of the electroslag ingot.

[0030] C. When the electroslag electrode 2 is smelted to the diameter reduction step L, the melting rate is immediately reduced to 10% to 20% of the normal melting rate, and the voltage is set to 70% to 80% of the normal smelting voltage, so that the electrode slowly melts the diameter reduction part.

[0031] D. When the electroslag electrode 2 has 30 to 50 mm of smelting remaining, reduce the melting rate to 0.5 to 1.0 kg / min again and reduce the voltage to 40% to 50% of the normal smelting voltage, so that the electroslag electrode stops melting and keeps warm for more than 30 minutes, and then cut off the power.

[0032] by Take ingot-type electroslag ingot as an example. The depth of the shrinkage cavity of the ingot-shaped electroslag ingot is 130mm, and the diameter of the shrinkage cavity is According to the cone volume formula V = 1 / 3Sh and the volume density weight formula T = ρV, the weight of the filled pit can be roughly calculated to be about 96kg, that is, L is inversely calculated based on 96kg. For example, the normal electrode diameter D is The diameter d of the local contraction area is The inferred height is about 100mm, plus the 30-50mm tail L=100+30-50=130-150mm. Figure 2 shown.

[0033] The present invention can more quickly reduce the depth of the molten pool 4 and the heat of the molten pool 4 during the electroslag shrinkage feeding stage, and the molten steel in the reduced diameter portion of the electroslag electrode effectively drips into the center of the shrinkage cavity to complete the filling.

Claims

1. A single-arm large-tonnage electroslag ingot feeding method, characterized in that: It includes the following steps: A. Weld the electroslag dummy electrode to the nozzle end of the electroslag electrode, install the electroslag electrode on the electroslag furnace, supply power to the electroslag furnace, and set the melting rate to 0.9D / h kg / min during the steady state process, where D is the diameter of the electroslag ingot; B. When the remaining weight of the electroslag electrode is 1000kg, it enters the shrinkage feeding stage. The electroslag electrode is melted and filled into the slag pool to feed the shrinkage holes. First, the power is reduced to reduce the melting speed to reduce the shrinkage holes of the electroslag ingot; C. When the electroslag electrode is smelted to the reduced diameter step L, the melting speed and voltage are immediately reduced to allow the electroslag electrode to slowly melt the reduced diameter part; D. When the electroslag electrode has 30 to 50 mm of smelting remaining, reduce the melting rate and voltage again to stop melting the electroslag electrode and keep it warm for more than 30 minutes, then turn off the power.

2. A single-arm large-tonnage electroslag ingot feeding method according to claim 1, characterized in that: In the step B, after shrinkage compensation, the melting rate is reduced to 1 / 2 to 1 / 3 of the normal smelting melting rate.

3. A single-arm large-tonnage electroslag ingot feeding method according to claim 1, characterized in that: In the step C, the melting rate is reduced to 10% to 20% of the normal melting rate, and the voltage is set to 70% to 80% of the normal smelting voltage.

4. A single-arm large-tonnage electroslag ingot feeding method according to claim 1, characterized in that: In the step D, the melting rate is reduced again to 0.5-1.0 kg / min, and the voltage is set to 40%-50% of the normal smelting voltage.

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