Electromagnetic smelting method for reducing cold rolling defects of if steel

Abstract

The application discloses an electromagnetic smelting method for reducing cold rolling defects of IF steel, and after refining is completed, aluminum slag is added at a temperature sampling position to reduce the generation of Al2O3 in molten steel caused by secondary oxidation of top slag of a ladle, then a covering agent is added into a tundish, and the covering agent is added into different positions of the tundish during continuous casting to avoid the generation of Al2O3 caused by secondary oxidation of molten steel in the tundish, and meanwhile, the covering agent avoids the slag crust in the tundish, and then different electromagnetic stirring currents are matched according to different production sections in a crystallizer to fragment inclusions and reduce the cold rolling defects of the IF steel.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of continuous casting technology improvement, and particularly relates to an electromagnetic smelting method for reducing cold-rolled defects of IF steel, and especially to improving the quality of continuous casting slabs in continuous casting steel production. BACKGROUND

[0002] Inclusion defects are a common and harmful type of defects in cold-rolled sheets, especially for IF steel which has extremely high requirements for the surface quality of cold-rolled sheets. Inclusion defects seriously affect the surface quality of cold-rolled sheets. In terms of the prior art, the cold-rolled sheet technology for IF steel mainly involves electromagnetic stirring equipment, cooling, winding used in the production process, that is, a large amount of technology is used to explain how to achieve electromagnetic stirring. However, in the casting process of a certain electromagnetic stirring equipment on a fixed mold and the corresponding refined molten steel, the suitable mold liquid level setting position, that is, the electromagnetic stirring magnetic field strength applied to the mold, especially the range of the upper end of the mold, is less involved in the current technology. For example, patent publication CN1434145A discloses a production method of S and Al containing continuous casting alloy steel, in which the first end electromagnetic stirring is given a stirring scheme of 250-320 A and 5.0 Hz, and the action of the electromagnetic stirring on inclusions in the mold is not described in depth, and only a current scheme of 300 A is recommended for the current of the electromagnetic stirring. Patent publication CN103849711A gives a suggestion of electromagnetic stirring for 20Cr steel deoxidized by aluminum, which is the specific position of the electromagnetic stirring, and the parameters are not further described. Patent publication CN107457379A gives a stirring current of 200-300 A and a stirring frequency of 1.0-1.5 Hz for the quality problem of high alloy bearing steel, and does not describe the recommended value of the stirring current for different mold sizes.

[0003] From the above analysis of the use of electromagnetic stirring in different technologies, the role, mechanism and technical route of electromagnetic stirring in the continuous casting mold are not very clear and explicit. Cold-rolled sheets are sensitive to inclusions, and general steel enterprises use electromagnetic stirring to remove inclusions. However, how to realize different stirring current parameters under different production conditions in the continuous casting process needs to be further researched and explored. From the known technologies in China, the stirring current is generally fixed, but the dynamic current is not changed in a targeted manner.

[0004] In order to further optimize and improve the metallurgical effect of electromagnetic stirring, the metallurgical effect of electromagnetic stirring needs to be refined and improved in combination with the on-site process conditions, so as to maximize the use of electromagnetic stirring equipment, improve the slab quality and improve the enterprise benefits. SUMMARY

[0005] In view of the above-mentioned defects in the prior art, the purpose of the present application is to provide an electromagnetic smelting method for reducing cold rolling defects of IF steel, wherein after refining is completed, aluminum slag is added at a temperature sampling position of a ladle to reduce the generation of Al2O3 in molten steel caused by secondary oxidation of top slag of the ladle, then a covering agent is added into a tundish, and the covering agent is added into different positions of the tundish during continuous casting to avoid the generation of Al2O3 caused by secondary oxidation of molten steel in the tundish and the slag crust in the tundish, and then different electromagnetic stirring currents are matched according to different production sections in a crystallizer to fragment inclusions and reduce cold rolling defects of IF steel, especially for the problem of high cold rolling defects at a small section, and the inclusions in the steel are removed by strengthened stirring.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] The present application provides an electromagnetic smelting method for reducing cold rolling defects of IF steel, comprising the following steps:

[0008] S1, after refining is completed, aluminum slag is added at a temperature sampling position of a ladle;

[0009] S2, after molten steel in the ladle is poured into a tundish, a covering agent is added into the tundish after opening of the tundish, and the covering agent is added into different positions on the surface of the tundish during continuous casting of the tundish;

[0010] S3, after molten steel in the tundish is transferred to a crystallizer, inclusions in the crystallizer are fragmented by electromagnetic stirring to reduce the content of inclusions in the molten steel.

[0011] Preferably, in the step S1, the content of aluminum in the aluminum slag is 40-45wt%.

[0012] Preferably, in the step S1, the added amount of the aluminum slag is calculated by the following formula:

[0013]

[0014] In the formula, m 铝渣 is the added amount of the aluminum slag, unit: kg;

[0015] w FeO is the mass percentage of FeO in the ladle slag, unit: wt%;

[0016] m 钢包渣 is the mass of the ladle slag in the ladle, unit: kg;

[0017] w Al is the mass percentage of Al in the aluminum slag, unit: wt%.

[0018] Preferably, in the step S2, the covering agent is added from the preheating hole and the ladle pouring hole of the tundish respectively during the tundish continuous casting process.

[0019] Preferably, in the step S2, the covering agent is added in an amount of 600-800 kg after the tundish is opened.

[0020] Preferably, in the step S2, 10-30 kg of the covering agent is added from the preheating hole and the ladle pouring hole of the tundish respectively during the tundish continuous casting process.

[0021] Preferably, in the step S3, the electromagnetic stirring current is 300-700 A during the electromagnetic stirring process.

[0022] Preferably, in the step S3, the electromagnetic stirring current is controlled to be 601-700 A when the crystallizer produces a small section of 800-1100 mm, 501-600 A when the crystallizer produces a medium section of 1101-1400 mm, and 300-400 A when the crystallizer produces a large section of 1401-1900 mm during the electromagnetic stirring process.

[0023] The electromagnetic smelting method for reducing cold rolling defects of IF steel provided by the present application has the following beneficial effects:

[0024] 1. The electromagnetic smelting method for reducing cold rolling defects of IF steel provided by the present application, after refining is completed, adds aluminum slag at the refining station to reduce the generation of secondary oxide Al2O3 in the molten steel caused by FeO in the ladle top slag, then adds a covering agent into the tundish and adds the covering agent to different positions on the surface of the tundish during the continuous casting process to avoid the secondary oxidation of Al2O3 caused by the contact of the molten steel in the tundish with air, and to avoid the slag crust in the tundish; then, different electromagnetic stirring currents are matched according to different production sections in the crystallizer to fragment the inclusions, promote the fine inclusions to cross the steel / slag interface and enter the protective slag, reduce the inclusions of Al2O3 in the molten steel, and thus reduce the cold rolling defects of IF steel.

[0025] 2. The electromagnetic smelting method for reducing cold rolling defects of IF steel provided by the present application can be widely used in the production process of continuous casting steel, can effectively reduce the inclusions in the cold rolled plate of IF steel, avoid the cold rolling defects of IF steel, and has the characteristics of improving the billet yield.

[0026] 3. The electromagnetic smelting method for reducing cold rolling defects of IF steel provided by the present application matches different electromagnetic stirring currents according to different production sections in the crystallizer, thereby specifically solving the quality problems of the billets of different sections, especially the more defects of small sections. DETAILED DESCRIPTION

[0027] In order to better understand the above technical solutions of the present application, the technical solutions of the present application are further explained below in combination with examples.

[0028] In the converter steelmaking process, the refining treatment is used for temperature adjustment and alloying, and the continuous casting in the steelmaking plant is the last process to complete the transformation from liquid to solid. In the continuous casting process, the molten steel is solidified in the crystallizer; in order to prevent the molten steel from being oxidized and to prevent the temperature from dropping too much, a protective slag is needed for heat insulation and heat preservation; however, the protective slag on the surface of the molten steel is captured by the solidified shell due to the effect of electromagnetic stirring. For different casting machines and different electromagnetic stirring equipment, optimization is needed after a period of production. Since most of the magnetic fields are several pairs of electromagnetic group windings, under the action of alternating current, the magnetic field is generated alternately, so that the force acting on the liquid surface pushes the liquid surface to rotate, thereby playing a stirring role. However, since the magnetic lines need to be closed, the electromagnetic field at both ends of the winding is the weakest, and the electromagnetic field in the middle of the winding is the strongest. Therefore, how to set the electromagnetic stirring current of the production liquid surface and reasonably utilize the magnetic field strength according to the height of the production liquid surface, and ultimately achieve the stirring of inclusions and the avoidance of excessive stirring of the liquid surface to cause quality problems in the subsequent process, especially the problem of protective slag involvement, is particularly important in the production of cast steel in the crystallizer.

[0029] At present, the traditional idea of electromagnetic stirring is to wash the bubbles and inclusions solidified on the shell. Non-metallic inclusions are removed; but the molten slag caused by stirring is not considered. At the same time, the effect of electromagnetic stirring on the deoxidation product of IF steel is not given. After investigation and sampling analysis, the deoxidation product Al2O3 in the ladle after refining treatment shows a dispersed distribution, part of which floats to the ladle slag, and part of which aggregates and grows in the molten steel. When the deoxidation product Al2O3 is poured from the tundish to the crystallizer, due to the aggregation and growth to a certain size, the size of the deoxidation product is the largest from smelting to continuous casting. When the molten steel flows from the tundish to the crystallizer, the deoxidation product follows the steel flow from the submerged nozzle into the crystallizer. When the size of the inclusions is larger, electromagnetic stirring is the last process to ensure the purity of the molten steel; since electromagnetic stirring plays a role in breaking the size of the deoxidation inclusions; the behavior of inclusions in the molten steel at the nozzle to the meniscus needs to be optimized. From the actual use on site, the high content of small cross-section inclusions, the high content of cold-rolled automobile plate inclusions, and the low content of large cross-section inclusions. Generally, it is believed that the impact depth of small cross-section is deep, and the impact of large cross-section is shallow, and the inclusions float fully. However, from the view of the rolling slag of hot-rolled plate, the occurrence of large cross-section continuous casting slab is high, and the occurrence of small cross-section is low. Comparing the cold-rolled defects with the hot-rolled defects, the floating of inclusions and the protection system involved are a pair of common bodies, and the floating of inclusions in the molten steel to the protective slag and the capture of the protective slag by the molten steel are a pair of contradictory bodies; this is not a problem of impact depth, but a problem of the behavior of slag / gold interface in the process of contact between molten steel and protective slag at the meniscus. In large cross-section, the molten slag in the molten steel is easy to be involved in the molten steel, but in small cross-section, the liquid protective slag can more fully absorb the inclusions in the molten steel.

[0030] Generally, the refining treatment of IF steel reduces the cold-rolled defects by reducing the deoxidation end oxygen or adding carbon in the ladle slag before refining treatment, carrying out vacuum combustion to remove excessive free oxygen in the molten steel and reduce the amount of deoxidation product Al2O3. However, the ladle slag after refining treatment has oxidizing property and is easy to cause secondary oxidation. In the tundish pouring, air oxidation also causes secondary oxidation. And during the use of electromagnetic stirring, the solidification parameters are not conducive to the control of inclusions. Based on the above situation, in order to fundamentally solve the problem of inclusions, from the total amount of inclusions to the amount of secondary oxidation of oxides in the crystallizer, from refining to continuous casting, the electromagnetic smelting method for reducing cold-rolled defects of IF steel provided by the present application comprises the following steps:

[0031] S1, after refining, aluminum slag is added at the temperature sampling point of the ladle;

[0032] After refining, some aluminum dregs are put into the refining station, wherein the aluminum dregs are composed of 40-45wt% of metallic aluminum and other components, mainly including CaO, Al2O3, etc.; the aluminum dregs are put in to reduce the FeO content in the ladle slag and reduce the generation of Al2O3 in the molten steel caused by secondary oxidation of the ladle top slag. The Al2O3 generated by the molten steel pollution of the ladle slag oxygen after the refining process is controlled in total amount. The amount of aluminum dregs put in can be calculated according to the FeO content of the ladle slag and the amount of the ladle slag in the ladle according to the aluminum content of the aluminum dregs; the specific calculation is according to the following chemical reaction formula:

[0033] 3FeO+2Al=3Fe+Al2O3 (1)

[0034] According to formula (1), the following is obtained:

[0035] m FeO =2m Al (2)

[0036] In formula (2), m FeO is the mass of FeO in the ladle slag, and m Al is the mass of Al in the aluminum dregs; according to formula (2), the amount of aluminum dregs added is calculated by the following formula:

[0037]

[0038] In the formula, m 铝渣 is the amount of aluminum dregs added, with the unit of kg;

[0039] w FeO is the mass percentage of FeO in the ladle slag, with the unit of wt%;

[0040] m 钢包渣 is the mass of the ladle slag in the ladle, with the unit of kg;

[0041] w Al is the mass percentage of Al in the aluminum dregs, with the unit of wt%.

[0042] After the molten steel in the ladle S2 is poured into the tundish, a covering agent is put into the tundish after the tundish is opened, and the covering agent is put into different positions on the surface of the tundish during continuous casting of the tundish;

[0043] In order to reduce the secondary oxidation of the molten steel in the tundish and increase the Al2O3, and avoid the tundish slag crust, a certain amount of covering agent is put into the tundish, and during the continuous casting process, a certain amount of covering agent is put into different positions of the tundish surface to avoid the tundish slag crust. After the tundish is opened, the amount of covering agent added is 600-800 kg. During the continuous casting process, the covering agent is added from the preheating hole and the ladle pouring hole of the tundish, wherein 10-30 kg of covering agent is added to the preheating hole and the ladle pouring hole of the tundish, respectively.

[0044] S3, after the molten steel in the tundish is transferred to the crystallizer, the inclusions in the crystallizer are crushed by electromagnetic stirring to reduce the content of inclusions in the molten steel.

[0045] In the crystallizer, the electromagnetic stirring equipment is arranged below the meniscus of the crystallizer to above the continuous casting discharge hole according to the conventional method. Different electromagnetic stirring currents are matched according to different sections, mainly according to the maximum use current and the lower use current to match the section process of continuous casting production. For small sections, a large current is matched to crush the size of inclusions, and small inclusions are easily captured by the protective slag at the slag-metal interface. For large sections, a small current is matched. Due to the large fluctuation of the liquid surface of the large section, the smaller current can weaken the influence on the liquid surface, and can avoid the inclusions being rolled into the molten steel. The electromagnetic stirring current can be controlled between 300A and 700A; specifically, different electromagnetic stirring currents can be matched according to the production section size of the crystallizer, according to small, medium and large sections. The production section is from 800mm to 1900mm, according to small, medium and large, that is, 800-1100mm is a small section, the electromagnetic stirring current is 601-700A; 1101-1400mm is a medium section, the electromagnetic stirring current is 501A-600; 1401-1900mm is a large section, the electromagnetic stirring current is 300A-400A.

[0046] Through the above method, the content of inclusions in the final IF steel cold-rolled plate can be controlled to reduce the cold-rolled defect rate (calculated according to weight) to less than 5%.

[0047] The electromagnetic smelting method for reducing IF steel cold-rolled defects of the present application will be further described below with specific examples.

[0048] Example 1

[0049] In this example, the electromagnetic smelting method for reducing IF steel cold-rolled defects of the present application is used for a certain day production of a furnace of IF steel, and the specific process is as follows:

[0050] I. In the temperature sampling position, several aluminum slag is put in, the aluminum slag composition is 40% of metal aluminum, and other components, mainly including CaO, Al2O3. The aluminum slag reduces the FeO in the slag, reduces the generation of Al2O3 in the molten steel caused by the secondary oxidation of the ladle top slag. From the total amount, the Al2O3 generated by the molten steel pollution of the ladle slag oxygen after the refining treatment is controlled. The amount of aluminum slag put in can be calculated according to the FeO content of the ladle slag and the amount of slag in the ladle according to the aluminum content of the aluminum slag. During the converter tapping process, the amount of slag flowing into the ladle from the converter is 1000 kg, and the total amount of aluminum slag and lime added is 1000 kg. From the end of the converter tapping to the refining station, the total amount of the ladle top slag is 2000 kg, among which the aluminum slag has not been added before the refining treatment starts, and the aluminum slag is added after the converter tapping is completed. After the refining treatment is completed, the FeO content in the ladle slag is 6%, that is, the FeO content in the ladle slag is 1000*6% = 60 kg, according to the following reaction formula:

[0051] 3FeO + 2Al = 3Fe + Al2O3

[0052] According to the above reaction, 30 kg of metal aluminum should be added, and the aluminum content in the aluminum slag is 40%, so 75 kg of aluminum slag is needed. In the refining station, 7-8 bags of aluminum slag are put in according to 10 kg per bag.

[0053] II. In order to reduce the increase of Al2O3 caused by the secondary oxidation of the molten steel in the tundish and avoid the tundish slag crust, a certain amount of covering agent is put into the tundish, and a certain amount of covering agent is put into different positions of the tundish during continuous casting of the tundish, so as to avoid the tundish slag crust. The amount of covering agent put into the tundish is 600-800 kg, and then 3 bags of covering agent are put into each ladle during the continuous casting of other ladles, and one bag is put into each of the two preheating holes and the ladle pouring hole, each bag weighing 10-15 kg.

[0054] III. In the crystallizer, different electromagnetic stirring currents are matched according to different sections; mainly according to the maximum current and lower current, the electromagnetic stirring process is matched, and the production section of the crystallizer of this furnace is 1750 mm, and the current is 300A-400A.

[0055] Through the above method, the cold rolled sheet of IF steel produced in this furnace has a cold rolling defect rate of less than 4.5%.

[0056] Example 2

[0057] In this example, the electromagnetic smelting method for reducing the cold rolling defects of IF steel is used when a furnace of IF steel is produced on a certain day, and the specific process is as follows:

[0058] I. In the temperature sampling position, several aluminum slag is put in, the aluminum slag composition is 45% of metal aluminum, and other components, mainly including CaO, Al2O3. The aluminum slag reduces the FeO in the slag, reduces the generation of Al2O3 in the molten steel caused by the secondary oxidation of the ladle top slag. From the total amount, the Al2O3 generated by the molten steel pollution of the ladle slag oxygen after the refining treatment is controlled. The amount of aluminum slag added can be calculated according to the FeO content of the ladle slag and the amount of slag in the ladle according to the aluminum content of the aluminum slag. During the converter tapping process, the amount of slag flowing into the ladle from the converter is 1500kg, and the total amount of aluminum slag and lime added is 1500kg. From the end of the converter tapping to the refining station, the total amount of the ladle top slag is 3000kg, among which the aluminum slag has not been added before the refining treatment starts, and the aluminum slag is added after the converter tapping is completed. After the refining treatment is completed, the FeO content in the ladle slag is 6%, that is, the FeO content in the ladle slag is 1500*6% = 90kg, according to the following reaction formula:

[0059] 3FeO+2Al=3Fe+Al2O3

[0060] According to the above reaction, 45kg of metal aluminum should be added, and the aluminum content in the aluminum slag is 45%, so 100kg of aluminum slag is needed. In the refining station, 10 bags of aluminum slag are put in according to 10kg per bag.

[0061] II. In order to reduce the increase of Al2O3 caused by the secondary oxidation of the molten steel in the tundish and avoid the tundish slag crust, a certain amount of covering agent is put into the tundish, and a certain amount of covering agent is put into different positions of the tundish during continuous casting of the tundish, so as to avoid the tundish slag crust. The amount of covering agent put into the tundish is 600-800kg, and then 6 bags of covering agent are put into each ladle during the continuous casting of other ladles, and 2 bags of covering agent are put into two preheating holes and ladle pouring holes, each bag is 10-15kg.

[0062] III. In the crystallizer, different electromagnetic stirring currents are matched according to different sections; mainly according to the maximum current and lower current, the electromagnetic stirring process is matched. The production section of the crystallizer of this furnace is 1150mm, and the current is 501A-600A.

[0063] Through the above method, the cold rolled sheet of IF steel produced in this furnace has a cold rolling defect rate of less than 4%.

[0064] Example 3

[0065] This example is a certain day of IF steel production using the electromagnetic smelting method for reducing the defects of IF steel cold rolling of the present application, the specific process is as follows:

[0066] I. In the temperature sampling position, several aluminum slag is put in, the aluminum slag composition is 40% of metal aluminum, and other components, mainly including CaO, Al2O3. The aluminum slag reduces the FeO in the slag, reduces the generation of Al2O3 in the molten steel caused by the secondary oxidation of the ladle top slag. From the total amount, the Al2O3 generated by the molten steel pollution of the ladle slag oxygen after the refining treatment is controlled. The amount of aluminum slag put in can be calculated according to the FeO content of the ladle slag and the amount of slag in the ladle according to the aluminum content of the aluminum slag. During the converter tapping process, the amount of slag flowing into the ladle from the converter is 800 kg, and the total amount of aluminum slag and lime added is 800 kg. From the end of the converter tapping to the refining station, the total amount of the ladle top slag is 1600 kg, among which the aluminum slag has not been added before the refining treatment starts, and the aluminum slag is added after the converter tapping is completed. After the refining treatment is completed, the FeO content of the ladle slag is 6%, that is, the FeO content of the ladle slag is 800*6% = 48 kg. According to the following reaction formula:

[0067] 3FeO + 2Al = 3Fe + Al2O3

[0068] According to the above reaction, 24 kg of metal aluminum should be added, and the aluminum content in the aluminum slag is 40%, so 60 kg of aluminum slag is needed. At the refining station, 6-7 bags of aluminum slag are put in according to 10 kg per bag.

[0069] II. In order to reduce the increase of Al2O3 caused by the secondary oxidation of the molten steel in the tundish and avoid the tundish slag crust, a certain amount of covering agent is put into the tundish, and a certain amount of covering agent is put into different positions of the tundish during continuous casting of the tundish, so as to avoid the tundish slag crust. The amount of covering agent put into the tundish is 600-800 kg, and then 3 bags of covering agent are put into each ladle during the continuous casting of other ladles, one bag is put into each of the two preheating holes and the ladle pouring hole, and each bag weighs 10-15 kg.

[0070] III. In the crystallizer, different electromagnetic stirring currents are matched according to different sections; mainly according to the maximum use current and the lower use current, the electromagnetic stirring process is matched. The production section of the crystallizer of this furnace is 1550 mm, and the current is 300 A-400 A.

[0071] Through the above method, the cold rolled sheet of IF steel produced in this furnace has a cold rolling defect rate of less than 4.2%.

[0072] Those skilled in the art in this technical field should realize that the above embodiments are only used to illustrate the present application, and are not used as a limitation of the present application, as long as the changes and modifications of the above described embodiments are within the scope of the spirit of the present application.

Claims

1. An electromagnetic smelting method for reducing cold-rolled defects of IF steel, characterized by, The method comprises the following steps: S1, after refining, adding aluminum slag to the temperature sampling point of the ladle; S2, after pouring the molten steel in the ladle into the tundish, adding covering agent to the tundish after opening the tundish, and adding covering agent to different positions of the tundish during continuous casting of the tundish; S3, after transferring the molten steel in the tundish to the crystallizer, fragmenting the inclusions in the crystallizer by electromagnetic stirring to reduce the content of inclusions in the molten steel; In the step S1, the content of aluminum in the aluminum slag is 40-45wt%. In the step S1, the adding amount of the aluminum slag is calculated by the following formula: In the formula, m 铝渣 is the addition amount of aluminum dregs, in kg; w FeO FeO is the mass percentage of FeO in the ladle slag, in wt%; m 钢包渣 m is the mass of the ladle slag in the ladle, in kg; w Al w is the mass percentage of Al in the aluminum slag, in wt%.

2. The electromagnetic metallurgical method of reducing cold rolling defects of IF steel according to claim 1, characterized in that, In the step S2, during continuous casting of the tundish, covering agent is added from the preheating hole and the ladle pouring hole of the tundish respectively.

3. The electromagnetic metallurgical process for reducing cold rolling defects of IF steel according to claim 2, characterized in that, In the step S2, after opening the tundish, the adding amount of the covering agent is 600-800kg.

4. The electromagnetic metallurgical process for reducing cold rolling defects of IF steel according to claim 2, characterized in that, In the step S2, during continuous casting of the tundish, 10-30kg of covering agent is added to the preheating hole and the ladle pouring hole of the tundish respectively.

5. The electromagnetic melting process for reducing cold-rolled defects of IF steel according to claim 1, characterized in that, In the step S3, during the electromagnetic stirring, the electromagnetic stirring current is 300-700A.

6. The electromagnetic metallurgical process for reducing cold rolling defects of IF steel according to claim 5, characterized in that, In the step S3, during the electromagnetic stirring, when the production section of the crystallizer is small section of 800-1100mm, the electromagnetic stirring current is controlled to be 601-700A; when the production section of the crystallizer is medium section of 1101-1400mm, the electromagnetic stirring current is controlled to be 501-600A; when the production section of the crystallizer is large section of 1401-1900mm, the electromagnetic stirring current is controlled to be 300-400A.

Images