Device and method for preparing large steel ingot by conductive crystallizer electroslag remelting method

文档序号:146902 发布日期:2021-10-26 浏览:16次 中文

阅读说明:本技术 导电结晶器电渣重熔法制备大型钢锭的装置及方法 (Device and method for preparing large steel ingot by conductive crystallizer electroslag remelting method ) 是由 董艳伍 侯志文 姜周华 胡志豪 于 2021-07-23 设计创作,主要内容包括:一种导电结晶器电渣重熔法制备大型钢锭的装置及方法,包括电源、上部结晶器、下部结晶器、引锭板;上部结晶器有绝缘段、上导电段和下导电段;上导电段、下导电段、自耗电极和引锭板分别与电源连接;方法为:(1)装配自耗电极;引锭板与下部结晶器下沿填充密封;(2)熔渣倒入上部结晶器;(3)停止倒入熔渣,开关合闸分别构成不同供电回路,焦耳热将自耗电极加热熔化;(4)金属熔池时启动抽锭系统;(5)控制金属熔池并通过液位检测仪监测液面高度;(6)凝固坯体达到目标长度时,停止抽锭,断开供电回路。本发明的方法通过改变导电段的位置以及数量进而改变电流路径,对温度场进行了合理的优化,为铸锭减轻元素偏析,改善铸锭的表面质量提供了保障。(A device and method for preparing large-scale steel ingot by conductive crystallizer electroslag remelting method comprises a power supply, an upper crystallizer, a lower crystallizer and a dummy plate; the upper crystallizer is provided with an insulating section, an upper conductive section and a lower conductive section; the upper conductive section, the lower conductive section, the consumable electrode and the dummy bar are respectively connected with a power supply; the method comprises the following steps: (1) assembling a consumable electrode; the dummy bar plate and the lower edge of the lower crystallizer are filled and sealed; (2) pouring the slag into an upper crystallizer; (3) stopping pouring the molten slag, closing a switch to form different power supply loops respectively, and heating and melting the consumable electrode by joule heat; (4) starting a stripping system when the metal molten pool is molten; (5) controlling a molten metal bath and monitoring the liquid level height through a liquid level detector; (6) and when the solidified blank reaches the target length, stopping ingot pulling and disconnecting the power supply loop. The method changes the current path by changing the position and the number of the conductive segments, reasonably optimizes the temperature field, and provides guarantee for reducing element segregation and improving the surface quality of the ingot.)

1. A device for preparing large-sized steel ingots by a conductive crystallizer electroslag remelting method is characterized by comprising a power supply, an upper crystallizer, a lower crystallizer and a dummy bar plate; the upper crystallizer is sequentially provided with an insulating section, an upper conductive section and a lower conductive section from top to bottom, wherein a first high-temperature-resistant insulating gasket is arranged between the insulating section and the upper conductive section, a second high-temperature-resistant insulating gasket is arranged between the upper conductive section and the lower conductive section, and a third high-temperature-resistant insulating gasket is arranged between the lower conductive section and the lower crystallizer; the upper conductive segment and the lower conductive segment are respectively connected with the first short net and the second short net, and the first short net and the second short net are simultaneously connected with the third short net; the third short network is connected with a fourth short network and a fifth short network through a third switch and a fourth switch respectively, the fourth short network is connected with one end of a sixth short network, and the other end of the sixth short network is used for being connected with a consumable electrode; the dummy bar plate is connected with one end of the seventh short net, and the other end of the seventh short net is connected with the eighth short net and the ninth short net through a fifth switch and a sixth switch respectively; the eighth short network and the fourth short network are simultaneously connected with one pole of the power supply, and the ninth short network and the fifth short network are simultaneously connected with the other pole of the power supply; the first short network is provided with a first switch, the second short network is provided with a second switch, and the sixth short network is provided with a seventh switch.

2. The apparatus for preparing large-sized steel ingot by electro-slag remelting process in a conductive crystallizer according to claim 1, wherein a sensor probe of a liquid level detector is mounted on the sidewall of the lower crystallizer; the sensor probe consists of an upper probe and a lower probe, and the vertical height difference between the upper probe and the lower probe is 15-20 mm; the upper probe is connected with the bottom surface of the third high-temperature-resistant insulating gasket, or the vertical distance between the upper probe and the third high-temperature-resistant insulating gasket is 20-50 mm.

3. The device for preparing the large steel ingot by the conductive crystallizer electroslag remelting method according to claim 1, wherein the thicknesses of the first high-temperature-resistant insulating gasket, the second high-temperature-resistant insulating gasket and the third high-temperature-resistant insulating gasket are 3-20 mm.

4. A method for preparing a large steel ingot by a conductive crystallizer electroslag remelting method is characterized by adopting the device of claim 1 and comprising the following steps:

(1) assembling a consumable electrode on a dummy electrode, suspending the dummy electrode on a beam support arm of an electroslag furnace, and enabling the axis of the consumable electrode to be overlapped with the axes of an upper crystallizer and a lower crystallizer; filling and sealing the dummy bar plate and the lower edge of the lower crystallizer by using magnesia and asbestos ropes;

(2) pouring the molten slag with the temperature reaching the preset temperature into an upper crystallizer to form a liquid slag pool; the slag is formed by melting slag systems, covering the slag with melted slag, heating the slag to a preset temperature, and pouring the slag from the slag covering; at the moment, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch and the seventh switch are in an off state;

(3) when the liquid level of the liquid slag pool is higher than the upper conductive segment and the vertical distance between the liquid slag pool and the top surface of the upper conductive segment exceeds 10mm, stopping pouring the molten slag, and switching on a first switch, a second switch, a fourth switch, a sixth switch and a seventh switch to enable a power supply, a consumable electrode, the liquid slag pool, a dummy plate, the upper conductive segment and the lower conductive segment to form a first power supply loop, wherein the dummy plate, the upper conductive segment and the lower conductive segment are connected in parallel; or when the pouring of the slag is stopped, switching on the first switch, the second switch, the third switch, the sixth switch and the seventh switch to enable the power supply, the consumable electrode, the liquid slag pool, the dummy plate, the upper conductive segment and the lower conductive segment to form a second power supply loop, wherein the upper conductive segment and the lower conductive segment are connected in parallel; or when the slag is stopped to be led in, the first switch, the second switch, the fourth switch and the seventh switch are switched on, so that the power supply, the consumable electrode, the liquid slag pool, the upper conductive segment and the lower conductive segment form a third power supply loop, wherein the upper conductive segment and the lower conductive segment are connected in parallel; or when the slag is stopped to be led in, switching on and off the first switch, the second switch, the fourth switch, the fifth switch and the seventh switch to enable the power supply, the consumable electrode, the liquid slag bath, the upper conductive section and the lower conductive section to form a fourth power supply loop, wherein the upper conductive section and the lower conductive section are connected in parallel; under the action of current, Joule heat generated by the liquid slag pool heats the consumable electrode to melt the consumable electrode;

(4) the metal liquid drops formed by melting the consumable electrode sink to the bottom of the liquid slag pool and gradually accumulate to form a metal molten pool; starting the ingot drawing system to lower the dummy bar plate; the molten metal pool is solidified under the cooling action of the lower crystallizer to form a solidified casting blank;

(5) controlling the liquid level of a metal molten pool between an upper probe and a lower probe assembled on the side wall of the lower crystallizer by controlling the descending speed of a dummy bar plate and the melting speed of a consumable electrode, and monitoring the liquid level height by a liquid level detector;

(6) and (3) gradually descending the dummy bar plate along with the proceeding of ingot drawing, stopping ingot drawing when the length of the solidified casting blank on the dummy bar plate reaches the target length, lifting the consumable electrode by the lifting device to separate from the liquid slag pool, disconnecting the first power supply loop, the second power supply loop or the third power supply loop, and cooling the solidified casting blank to the normal temperature to obtain a steel ingot.

5. The method for preparing a large steel ingot by an electro-slag remelting method of a conductive crystallizer according to claim 4, wherein in the step (3), the current ratio of the upper conductive segment and the lower conductive segment is adjusted by changing the depth of the consumable electrode inserted into the liquid slag bath and matching with the thickness of the second high-temperature-resistant insulating gasket; when the thickness of the second high-temperature-resistant insulating gasket is between 3mm and 20mm, the current ratio of the lower conductive segment to the upper conductive segment is controlled to be 5-0.5 times.

6. The method for preparing a large steel ingot by an electro-slag remelting method of a conductive crystallizer according to claim 4, wherein the diameter of the steel ingot is more than or equal to 300mm, and the length of the steel ingot is more than or equal to 1500 mm.

7. The method for manufacturing a large-sized steel ingot by an electro-slag remelting method in a conductive crystallizer according to claim 4, wherein cooling water circulates in a cooling water cavity inside the upper conductive section, cooling water circulates in a cooling water cavity inside the lower conductive section, and cooling water circulates in a cooling water cavity inside the lower crystallizer in the steps (2) to (6).

Technical Field

The invention belongs to the technical field of metallurgy, and particularly relates to a device and a method for preparing a large steel ingot by a conductive crystallizer electroslag remelting method.

Background

In recent years, the quality of heavy equipment forgings and steel ingots for special steel is widely concerned, and the use working conditions of large steel ingots such as rollers as main consumption equipment in steel rolling production become more severe; the performance of the roller directly affects the production efficiency of the rolling mill, the surface quality of the rolled material and the rolling cost. Therefore, how to manufacture steel ingots with proper size and satisfactory solidification structures and mechanical strength becomes a common concern in the metallurgical industry.

The traditional method for manufacturing the large-sized steel ingot generally has the defects of serious solidification structure segregation, complex manufacturing method, difficult forming and the like; the electroslag remelting process with conductive crystallizer can prepare large steel ingot, and change the ratio of different loop currents to reduce the melting speed of electrode and further reduce the segregation of ingot without deteriorating the surface quality of steel ingot.

However, when the conductive crystallizer is used for preparing the steel ingot, the obvious defect exists, and under the strong cooling action of the crystallizer, the slag pool near the lower end of the conductive section is basically in a solidification state because no current flows through the slag pool to form a joule heat effect, so the current mainly flows into the middle upper part of the conductive section from the consumable electrode. Therefore, the high-temperature area of the slag bath is mainly concentrated on the upper part of the slag bath, the high-temperature area is too close to the upper part, the bottom of the liquid slag bath has insufficient temperature, the molten metal bath is shallow, the molten steel is solidified too fast, the heat is not enough to melt the slag shell on the surface of the cast ingot, the slag shell on the surface of the cast ingot cladding layer is too thick, and the surface quality is poor.

In conclusion, the electroslag remelting method for the conductive crystallizer loop has the defect of poor surface quality in the process of preparing the steel ingot, and is not beneficial to preparing the large-size steel ingot with excellent performance and both surface quality and internal quality.

Disclosure of Invention

The invention aims to provide a device and a method for preparing a large steel ingot by a conductive crystallizer electroslag remelting method, which aim to change a current path by changing the positions and the number of conductive rings, further change or regulate the position of a high-temperature area of a slag bath, enable the high-temperature area of the slag bath to move downwards, improve the temperature and the depth of the edge of a metal molten bath, and further ensure the good surface quality of an ingot.

The device for preparing the large steel ingot by the conductive crystallizer electroslag remelting method comprises a power supply, an upper crystallizer, a lower crystallizer and a dummy plate; the upper crystallizer is sequentially provided with an insulating section, an upper conductive section and a lower conductive section from top to bottom, wherein a first high-temperature-resistant insulating gasket is arranged between the insulating section and the upper conductive section, a second high-temperature-resistant insulating gasket is arranged between the upper conductive section and the lower conductive section, and a third high-temperature-resistant insulating gasket is arranged between the lower conductive section and the lower crystallizer; the upper conductive segment and the lower conductive segment are respectively connected with the first short net and the second short net, and the first short net and the second short net are simultaneously connected with the third short net; the third short network is connected with a fourth short network and a fifth short network through a third switch and a fourth switch respectively, the fourth short network is connected with one end of a sixth short network, and the other end of the sixth short network is used for being connected with a consumable electrode; the dummy bar plate is connected with one end of the seventh short net, and the other end of the seventh short net is connected with the eighth short net and the ninth short net through a fifth switch and a sixth switch respectively; the eighth short network and the fourth short network are simultaneously connected with one pole of the power supply, and the ninth short network and the fifth short network are simultaneously connected with the other pole of the power supply; the first short network is provided with a first switch, the second short network is provided with a second switch, and the sixth short network is provided with a seventh switch.

In the device, a sensor probe of a liquid level detector is assembled on the side wall of the lower crystallizer; the sensor probe consists of an upper probe and a lower probe, and the vertical height difference between the upper probe and the lower probe is 15-20 mm; the upper probe is connected with the bottom surface of the third high-temperature-resistant insulating gasket, or the vertical distance between the upper probe and the third high-temperature-resistant insulating gasket is 20-50 mm.

In the device, the front end surfaces of the upper probe and the lower probe are flush with the inner wall of the lower crystallizer.

In the device, the upper conducting section is internally provided with a cooling water cavity for introducing cooling water.

In the device, the lower conducting section is internally provided with a cooling water cavity for introducing cooling water.

In the device, a cooling water cavity is arranged in the lower crystallizer and is used for introducing cooling water.

In the device, the thicknesses of the first high-temperature-resistant insulating gasket, the second high-temperature-resistant insulating gasket and the third high-temperature-resistant insulating gasket are 3-20 mm.

In the above device, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch, and the seventh switch are large current control switches.

The method for preparing the large steel ingot by the conductive crystallizer electroslag remelting method adopts the device and comprises the following steps:

1. assembling a consumable electrode on a dummy electrode, suspending the dummy electrode on a beam support arm of an electroslag furnace, and enabling the axis of the consumable electrode to be overlapped with the axes of an upper crystallizer and a lower crystallizer; filling and sealing the dummy bar plate and the lower edge of the lower crystallizer by using magnesia and asbestos ropes;

2. pouring the molten slag with the temperature reaching the preset temperature into an upper crystallizer to form a liquid slag pool; the slag is formed by melting slag systems, covering the slag with melted slag, heating the slag to a preset temperature, and pouring the slag from the slag covering; at the moment, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch and the seventh switch are in an off state;

3. when the liquid level of the liquid slag pool is higher than the upper conductive segment and the vertical distance between the liquid slag pool and the top surface of the upper conductive segment exceeds 10mm, stopping pouring the molten slag, and switching on a first switch, a second switch, a fourth switch, a sixth switch and a seventh switch to enable a power supply, a consumable electrode, the liquid slag pool, a dummy plate, the upper conductive segment and the lower conductive segment to form a first power supply loop, wherein the dummy plate, the upper conductive segment and the lower conductive segment are connected in parallel; or when the pouring of the slag is stopped, switching on the first switch, the second switch, the third switch, the sixth switch and the seventh switch to enable the power supply, the consumable electrode, the liquid slag pool, the dummy plate, the upper conductive segment and the lower conductive segment to form a second power supply loop, wherein the upper conductive segment and the lower conductive segment are connected in parallel; or when the slag is stopped to be led in, the first switch, the second switch, the fourth switch and the seventh switch are switched on, so that the power supply, the consumable electrode, the liquid slag pool, the upper conductive segment and the lower conductive segment form a third power supply loop, wherein the upper conductive segment and the lower conductive segment are connected in parallel; or when the slag is stopped to be led in, switching on and off the first switch, the second switch, the fourth switch, the fifth switch and the seventh switch to enable the power supply, the consumable electrode, the liquid slag bath, the upper conductive section and the lower conductive section to form a fourth power supply loop, wherein the upper conductive section and the lower conductive section are connected in parallel; under the action of current, Joule heat generated by the liquid slag pool heats the consumable electrode to melt the consumable electrode;

4. the metal liquid drops formed by melting the consumable electrode sink to the bottom of the liquid slag pool and gradually accumulate to form a metal molten pool; starting the ingot drawing system to lower the dummy bar plate; the molten metal pool is solidified under the cooling action of the lower crystallizer to form a solidified casting blank;

5. controlling the liquid level of a metal molten pool between an upper probe and a lower probe assembled on the side wall of the lower crystallizer by controlling the descending speed of a dummy bar plate and the melting speed of a consumable electrode, and monitoring the liquid level height by a liquid level detector;

6. and (3) gradually descending the dummy bar plate along with the proceeding of ingot drawing, stopping ingot drawing when the length of the solidified casting blank on the dummy bar plate reaches the target length, lifting the consumable electrode by the lifting device to separate from the liquid slag pool, disconnecting the first power supply loop, the second power supply loop or the third power supply loop, and cooling the solidified casting blank to the normal temperature to obtain a steel ingot.

In the method, cooling water circulates in a cooling water cavity in the upper conductive section, cooling water circulates in a cooling water cavity in the lower conductive section, and cooling water circulates in a cooling water cavity in the lower crystallizer.

In the method, the current ratio of the upper conductive segment and the lower conductive segment is adjusted by changing the depth of the consumable electrode inserted into the liquid slag bath and matching with the thickness of the second high-temperature-resistant insulating gasket; when the thickness of the second high-temperature-resistant insulating gasket is between 3mm and 20mm, the current ratio of the lower conductive segment to the upper conductive segment is controlled to be 5-0.5 times.

The diameter of the steel ingot is more than or equal to 300mm, and the length of the steel ingot is more than or equal to 1500 mm.

The method adopts liquid slag starting to increase the convenience of operation, changes a power supply loop in a remelting system, changes a current path by changing the position and the number of the conductive segments, reasonably optimizes a temperature field near a slag pool, particularly a slag-metal interface, improves the temperature at the slag-metal interface, particularly the temperature and the depth of the edge of a metal molten pool, reduces the thickness of a slag shell on the surface of a cast ingot, and prepares a steel ingot with better surface quality; the liquid level detector can dynamically monitor the position of the slag-metal interface in real time, and provides guarantee for reasonably adjusting the ingot drawing speed to ensure the stability of the slag-metal interface.

Drawings

FIG. 1 is a schematic structural diagram of an apparatus for preparing a large-sized steel ingot by a conductive crystallizer electroslag remelting method in an embodiment of the invention;

in the figure, 1, a power supply, 2, a consumable electrode, 3, a liquid slag bath, 4, a molten metal bath, 5, an insulating section, 6, a first high-temperature-resistant insulating gasket, 7, an upper conducting section, 8, a second high-temperature-resistant insulating gasket, 9, a third high-temperature-resistant insulating gasket, 10, a sensor probe, 11, a lower crystallizer, 12, a solidified casting blank, 13, a dummy bar plate, 14, a lower conducting section, 15, a first switch, 16, a second switch, 17, a third switch, 18, a fourth switch, 19, a fifth switch, 20, a sixth switch, 21 and a seventh switch.

Detailed Description

The consumable electrode adopted in the embodiment of the invention is made of Cr5 steel.

In the embodiment of the invention, the high-temperature resistant insulating gasket is made of asbestos.

The model of the liquid level detector in the embodiment of the invention is ML 0C-2M.

In the embodiment of the invention, the inner diameter of the upper conductive segment of the upper crystallizer is 420mm, wherein the height of the upper conductive segment is 30mm, and the height of the lower conductive segment is 10 mm.

The inner diameter of the lower crystallizer in the embodiment of the invention is 350 mm.

The diameter of the consumable electrode in the embodiment of the invention is 350 mm.

In the embodiment of the invention, under the condition that the heights of the upper conductive section and the lower conductive section are fixed and the total amount of the liquid slag is fixed, the liquid level position of the liquid slag is adjusted through the insertion depth of the consumable electrode; when the thickness of the second high-temperature-resistant insulating gasket is changed, the areas of the liquid slag contacted with the upper conducting section and the lower conducting section respectively are changed along with the change of the thickness of the second high-temperature-resistant insulating gasket, and the ratio of the two contact areas determines the ratio of the current passing through the upper conducting section and the lower conducting section; therefore, when a power supply loop is formed, when the upper conductive segment and the lower conductive segment are connected in parallel, the current ratio of the lower conductive segment and the upper conductive segment is controlled by changing the thickness of the second high-temperature-resistant insulating gasket, and the temperature distribution in the liquid slag pool is further controlled.

In the embodiment of the invention, the thicknesses of the first high-temperature-resistant insulating gasket, the second high-temperature-resistant insulating gasket and the third high-temperature-resistant insulating gasket are 3-20 mm.

In the embodiment of the invention, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch and the seventh switch are large-current control switches.

The length of the steel ingot in the embodiment of the invention is 2200 mm.

In the embodiment of the invention, the slag charge contains CaF according to mass percentage2 40~55%,CaO 15~25%,Al2O320~30%,MgO 0~5%,SiO20-10%, and the sum of the total components is equal to 100%.

In the embodiment of the invention, the melting speed of the consumable electrode is 220-400 kg/h.

Example 1

The structure of the device for preparing the large steel ingot by the electro-slag remelting method of the conductive crystallizer is shown in figure 1, and the device comprises a power supply 1, an upper crystallizer, a lower crystallizer 11 and a dummy bar plate 13;

the upper crystallizer is sequentially provided with an insulating section 5, an upper conductive section 7 and a lower conductive section 14 from top to bottom, wherein a first high-temperature-resistant insulating gasket 6 is arranged between the insulating section 5 and the upper conductive section 7, a second high-temperature-resistant insulating gasket 8 is arranged between the upper conductive section 7 and the lower conductive section 14, and a third high-temperature-resistant insulating gasket 9 is arranged between the lower conductive section 14 and the lower crystallizer 11;

the upper conductive segment 7 and the lower conductive segment 14 are respectively connected with a first short net and a second short net, and the first short net and the second short net are simultaneously connected with a third short net; the third short network is connected with a fourth short network and a fifth short network through a third switch 17 and a fourth switch 18 respectively, the fourth short network is connected with one end of a sixth short network, and the other end of the sixth short network is used for being connected with the consumable electrode 2; the dummy bar plate 13 is connected with one end of a seventh short net, and the other end of the seventh short net is connected with the eighth short net and the ninth short net through a fifth switch 19 and a sixth switch 20 respectively; the eighth short network and the fourth short network are simultaneously connected with one pole of the power supply 1, and the ninth short network and the fifth short network are simultaneously connected with the other pole of the power supply 1; a first switch 15 is arranged on the first short network, a second switch 16 is arranged on the second short network, and a seventh switch 21 is arranged on the sixth short network;

a sensor probe 10 of a liquid level detector is assembled on the side wall of the lower crystallizer 11; the sensor probe 10 consists of an upper probe and a lower probe, and the vertical height difference between the upper probe and the lower probe is 15 mm; the vertical distance between the upper probe and the third high-temperature-resistant insulating gasket 9 is 30 mm;

the front end surfaces of the upper probe and the lower probe are flush with the inner wall of the lower crystallizer 11;

a cooling water cavity is arranged in the upper conductive section 7 and used for introducing cooling water; a cooling water cavity is arranged in the lower conductive section 14 and used for introducing cooling water; a cooling water cavity is arranged in the lower crystallizer 11 and used for introducing cooling water;

the method for preparing the large steel ingot by the conductive crystallizer electroslag remelting method comprises the following steps:

assembling the consumable electrode 2 on the dummy electrode, suspending the dummy electrode on a beam support arm of the electroslag furnace, and enabling the axis of the consumable electrode 2 to be overlapped with the axes of the upper crystallizer and the lower crystallizer 11; filling and sealing the dummy bar plate 13 and the lower edge of the lower crystallizer 11 by using magnesia and asbestos ropes;

cooling water circulation in a cooling water cavity inside the upper conducting section 7; cooling water circulates in a cooling water cavity inside the lower conducting section 14; cooling water circulation in a cooling water cavity in the lower crystallizer 11;

pouring the molten slag with the temperature reaching the preset temperature into an upper crystallizer to form a liquid slag pool 3; the slag is formed by melting slag systems, covering the slag with melted slag, heating the slag to a preset temperature, and pouring the slag from the slag covering; at this time, the first switch 15, the second switch 16, the third switch 17, the fourth switch 18, the fifth switch 19, the sixth switch 20, and the seventh switch 21 are in an off state;

when the liquid level of the liquid slag pool 3 is higher than the upper conductive segment 7 and the vertical distance between the liquid slag pool and the top surface of the upper conductive segment 7 exceeds 10mm, stopping pouring molten slag, and switching on a first switch 15, a second switch 16, a fourth switch 18, a sixth switch 20 and a seventh switch 21 to enable a power supply 1, a consumable electrode 2, the liquid slag pool 3, a dummy bar plate 13, the upper conductive segment 7 and a lower conductive segment 14 to form a first power supply loop, wherein the dummy bar plate 13, the upper conductive segment 7 and the lower conductive segment 14 are connected in parallel; the consumable electrode 2 is heated by Joule heat generated by the liquid slag pool 3 under the action of current so as to start to melt;

the metal liquid drops formed by melting the consumable electrode 2 sink to the bottom of the liquid slag pool 3 and gradually accumulate to form a metal molten pool 4; starting the ingot drawing system to lower the dummy bar plate 13; the molten metal pool 4 is solidified under the cooling action of the lower crystallizer 11 to form a solidified casting blank 12;

controlling the liquid level of the metal molten pool 4 between an upper probe and a lower probe assembled on the side wall of the lower crystallizer 11 by controlling the descending speed of the dummy bar 13 and the melting speed of the consumable electrode 2, and monitoring the liquid level height by a liquid level detector;

the dummy bar plate 13 gradually descends along with the proceeding of ingot drawing, when the length of the solidified casting blank 12 on the dummy bar plate 13 reaches the target length, ingot drawing is stopped, the consumable electrode 2 is lifted by the lifting device to be separated from the liquid slag pool 3, the first power supply loop is disconnected, and the solidified casting blank 12 is cooled to the normal temperature to obtain a steel ingot;

in the process, the thickness of the second high-temperature-resistant insulating gasket 8 is set to be 3mm, and the current ratio of the lower conductive segment 14 to the upper conductive segment 7 is 5 times; the total current flowing in the consumable electrode 2 is 6000A, the current passing through the upper conductive segment 7 is 500A, the current passing through the lower conductive segment 14 is 2500A, and the current passing through the dummy bar 13 is 3000A;

the melting speed of the consumable electrode 2 is 300kg/h, the prepared steel ingot has good internal solidification quality and does not have defects of looseness, shrinkage cavity and the like, the element segregation degree is weakened, compared with the traditional method, the method is greatly reduced, slag inclusion and wrinkles do not exist on the surface of the cast ingot, the cutting amount is greatly reduced in the subsequent processing process, and the yield is greatly improved.

Example 2

The apparatus structure is different from embodiment 1 in that:

the vertical height difference between the upper probe and the lower probe is 20 mm; the vertical distance between the upper probe and the third high-temperature-resistant insulating gasket is 40 mm;

the method is different from the embodiment in that:

setting the thickness of the second high-temperature-resistant insulating gasket at 20mm, wherein the current ratio of the lower conductive section to the upper conductive section is 0.5 times; the current through the upper conductive segment is 2000A and the current through the lower conductive segment is 1000A;

the consumable electrode melting speed is 400kg/h, the prepared cast ingot has good internal solidification quality and does not have defects of looseness, shrinkage cavity and the like, the element segregation degree is slightly increased compared with that of the embodiment 1, compared with the traditional method, the method is greatly reduced, slag inclusion and wrinkles do not exist on the surface of the cast ingot, the cutting amount is greatly reduced in the subsequent processing process, and the yield is greatly improved.

Example 3

The apparatus structure is different from embodiment 1 in that:

the vertical height difference between the upper probe and the lower probe is 20 mm; the vertical distance between the upper probe and the third high-temperature-resistant insulating gasket is 40 mm;

the method is different from the embodiment in that:

(1) when the pouring of the slag is stopped, the first switch, the second switch, the third switch, the sixth switch and the seventh switch are switched on, so that the power supply, the consumable electrode, the liquid slag pool, the dummy plate, the upper conductive segment and the lower conductive segment form a second power supply loop, wherein the upper conductive segment and the lower conductive segment are connected in parallel;

(2) when the ingot pulling is stopped, the second power supply loop is disconnected;

(3) setting the thickness of the second high-temperature-resistant insulating gasket to be 3mm, wherein the current ratio of the lower conductive section to the upper conductive section is 2 times; the total current flowing into the consumable electrode is 3000A, the current passing through the upper conductive segment is 1000A, the current passing through the lower conductive segment is 2000A, and the current passing through the dummy bar is 6000A;

the consumable electrode melting speed is 220kg/h, the prepared cast ingot has good internal solidification quality and has no defects of looseness, shrinkage cavity and the like, the element segregation degree is greatly weakened compared with that of the cast ingot in example 1, slag inclusion and wrinkles do not exist on the surface of the cast ingot, the surface quality is very excellent, the cutting amount is greatly reduced in the subsequent processing process, and the yield is greatly improved.

Example 4

The apparatus structure is different from embodiment 1 in that:

the vertical height difference between the upper probe and the lower probe is 20 mm; the vertical distance between the upper probe and the third high-temperature-resistant insulating gasket is 40 mm;

the method is different from the embodiment in that:

(1) when the slag is stopped to be led in, the first switch, the second switch, the fourth switch and the seventh switch are switched on, so that the power supply, the consumable electrode, the liquid slag bath, the upper conductive segment and the lower conductive segment form a third power supply loop, wherein the upper conductive segment and the lower conductive segment are connected in parallel;

(2) when the ingot pulling is stopped, the third power supply loop is disconnected;

(3) setting the thickness of the second high-temperature-resistant insulating gasket to be 3mm, wherein the current ratio of the lower conductive section to the upper conductive section is 5 times; the total current flowing into the consumable electrode is 6000A, the current passing through the upper conductive segment is 1000A, the current passing through the lower conductive segment is 5000A, and the dummy plate is not electrified;

the melting speed of the consumable electrode is 350kg/h, the prepared cast ingot has good internal solidification quality and does not have defects of looseness, shrinkage cavity and the like, although the melting speed of the consumable electrode is improved, the element segregation degree is still greatly weakened compared with that of the cast ingot in the embodiment 1, slag inclusion and wrinkles do not exist on the surface of the cast ingot, the surface quality is very excellent, the cutting amount is greatly reduced in the subsequent processing process, and the yield is greatly improved.

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