Electromagnetic stirring dynamic adjustment method based on association of metallurgical slag components and cold rolling defects

Abstract

The application discloses a kind of based on metallurgical slag component and the dynamic adjustment method of electromagnetic stirring associated with cold rolling defects, according to historical data, construct with (CaO+MgO)‑(Al2O3+SiO2)‑FeO as the vertex ternary phase diagram, and mark the defect occurrence area of the refining finished slag in ternary phase diagram corresponding to the defective furnace, and with it as basis to judge the purity of molten steel, then according to the purity of molten steel dynamically adjusts argon flow and electromagnetic stirring process, to reduce molten steel inclusions, improve slab quality.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of continuous casting improvement, and particularly relates to an electromagnetic stirring dynamic adjustment method based on association of metallurgical slag components and cold rolling defects, and especially to improvement of quality of continuous casting slabs in continuous casting steel production. BACKGROUND

[0002] As for the current continuous casting improvement technology, most of them are about electromagnetic stirring equipment, cooling, winding, etc., that is, most of the current technologies are to explain how to realize electromagnetic stirring, and as for a certain electromagnetic stirring equipment on a fixed crystallizer, the corresponding refined molten steel in the casting process, the suitable crystallizer liquid level setting position, that is, the electromagnetic stirring magnetic field strength applied to the crystallizer, especially the range of the upper end of the crystallizer, is relatively less. For example, patent publication No. CN104690242 A discloses a dynamic control method for electromagnetic stirring position of steel continuous casting solidification end, which adopts a bidirectional linked list composed of continuous casting tracking units to establish a continuous casting dynamic tracking model, to collect continuous casting process parameters in real time, and to calculate continuous casting slab solidification information; by comparing the current electromagnetic stirring position with the optimal electromagnetic stirring position, the required displacement amount of the solidification end electromagnetic stirrer is calculated in real time; this technology theoretically discusses on the caster, but does not give a solution to the problem from the feedback of the quality result of the next process. Patent publication No. CN102554172 A discloses a slab continuous casting electromagnetic stirrer dynamic control method, characterized in that: (1) the steel grade, slab cross-sectional size, molten steel temperature and casting speed of the on-site continuous casting production are continuously collected by the continuous casting primary computer control system, and the collected various real-time data are transmitted to the continuous casting secondary computer; (2) the continuous casting secondary computer continuously processes the received various measured data to calculate the solidification shell thickness at the corresponding position of the electromagnetic stirring. There is no doubt that this method improves the electromagnetic stirring process for the shell, and the result is only to improve the shell, but does not adjust to the actual situation of the molten steel.

[0003] In the continuous casting production process, it is necessary to improve the purity of molten steel. At present, the commonly used method is electromagnetic stirring, which has the following two aspects: 1. Increase the floating efficiency of inclusions. 2. Billet shell washing, reduce the slag of solidification front. However, due to the use of solidification electromagnetic stirring parameters during the process of electromagnetic stirring, the purity of molten steel cannot be effectively judged, and only the fixed mode of electromagnetic stirring will have a big problem. First of all, when the purity of molten steel is poor, the argon flow of stopper should be opened to flush the stopper nodulation product, but if the purity of molten steel is good and the stopper nodulation is not serious, the argon should not be opened. The consequences of opening the argon are: the argon expands in the molten steel, the area is large, and the larger surface will adsorb the deoxidation product aluminum oxide. Therefore, the electromagnetic stirring has a great effect on removing argon bubbles, so the electromagnetic stirring must be put into use when the large argon is opened to prevent nodulation.

[0004] Therefore, how to judge the purity of molten steel and match different current stirring according to different degrees of molten steel are problems worth studying. SUMMARY

[0005] In view of the above defects existing in the prior art, the purpose of the present application is to provide a method for dynamically adjusting electromagnetic stirring based on the correlation between metallurgical slag components and cold rolling defects, a ternary phase diagram with (CaO+MgO)-(Al2O3+SiO2)-FeO as the end point is constructed according to historical data, and the defect occurrence area of the refining finished slag corresponding to the defective furnace is marked in the ternary phase diagram. The purity of molten steel is judged according to the above, and then the argon flow and the electromagnetic stirring process are dynamically adjusted according to the purity of molten steel, so as to reduce the inclusions in molten steel and improve the quality of slab.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0007] The present application provides a method for dynamically adjusting electromagnetic stirring based on the correlation between metallurgical slag components and cold rolling defects, comprising the following steps:

[0008] S1, a ternary phase diagram of metallurgical slag components is drawn according to the historical data in the continuous casting process, the defect occurrence area is marked according to the ladle refining finished slag corresponding to the quality defect of cold rolling plate in the continuous casting process, and the purity of molten steel is judged according to the distribution of the ladle refining finished slag in the ternary phase diagram of the metallurgical slag components;

[0009] S2, dynamically adjusting the argon flow according to the purity of molten steel;

[0010] S3, dynamically adjusting the stirring current of electromagnetic stirring according to the purity of molten steel.

[0011] Preferably, in the step S1, a ternary phase diagram of the metallurgical slag component is plotted with a first component, a second component and a third component as the top points of 100% in mass percentage, the first component is CaO+MgO, the second component is Al2O3+SiO2, and the third component is FeO.

[0012] Preferably, in the step S1, the purity of the molten steel is determined by the following method:

[0013] When the coordinates of the ladle refining completed slag fall into the defect occurrence area, the purity of the molten steel is defined as "poor";

[0014] When the coordinates of the ladle refining completed slag are located on the boundary of the defect occurrence area, the purity of the molten steel is defined as "medium";

[0015] When the coordinates of the ladle refining completed slag fall outside the boundary of the defect occurrence area, the purity of the molten steel is defined as "good".

[0016] Preferably, in the step S2, the argon flow rate is adjusted in the range of 3-18 L / min.

[0017] Preferably, in the step S2, taking the stopper argon flow rate of 10 L / min as the reference, when the purity of the molten steel is defined as "poor", the argon flow rate is increased to 15-18 L / min; when the purity of the molten steel is defined as "medium", the argon flow rate is adjusted to 8-11 L / min; and when the purity of the molten steel is defined as "good", the argon flow rate is adjusted to 5-6 L / min.

[0018] Preferably, in the step S3, taking the stirring current of electromagnetic stirring of 500-550 A as the reference, when the purity of the molten steel is defined as "poor", the stirring current is adjusted to 650-700 A; when the purity of the molten steel is defined as "medium", the stirring current is adjusted to 500-550 A; and when the purity of the molten steel is defined as "good", the stirring current is adjusted to 200-300 A.

[0019] The electromagnetic stirring dynamic adjustment method based on the correlation between the metallurgical slag component and the cold rolling defects provided by the present application has the following beneficial effects:

[0020] 1. The method for dynamically adjusting electromagnetic stirring based on the correlation between metallurgical slag components and cold rolling defects, according to historical data, a ternary phase diagram with (CaO+MgO)-(Al2O3+SiO2)-FeO as endpoints is constructed, and the defect occurrence area of the finished refining slag in the ternary phase diagram corresponding to the defective heat is marked, and the purity of the molten steel is judged based on this, and then the argon flow and the electromagnetic stirring process are dynamically adjusted according to the purity of the molten steel, so as to reduce the inclusions in the molten steel and improve the quality of the slab;

[0021] 2. Based on the basic principles of metallurgical slag in metallurgical physical chemistry, and the function of electromagnetic stirring to remove inclusions and bubbles, combined with the current continuous casting production process, the present application combines the purity of molten steel, dynamically adjusts the argon flow and the current of electromagnetic stirring, and the three cooperate with each other to increase the floating of inclusions in the molten steel, while avoiding the protective slag from being entrained into the molten steel, thereby improving the quality of the continuous casting slab;

[0022] 3. The method for dynamically adjusting electromagnetic stirring based on the correlation between metallurgical slag components and cold rolling defects can be widely used in the process of continuous steel production, reduces inclusions, and improves the quality of continuous casting slab. BRIEF DESCRIPTION OF DRAWINGS

[0023] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments, made with reference to the accompanying drawings:

[0024] Figure 1 The ternary phase diagram of the metallurgical slag components in the method for dynamically adjusting electromagnetic stirring based on the correlation between metallurgical slag components and cold rolling defects. DETAILED DESCRIPTION

[0025] In order to better understand the above technical solutions of the present application, the technical solutions of the present application will be further described below in combination with embodiments.

[0026] In the converter steelmaking process, refining treatment is carried out for temperature adjustment and alloying. The continuous casting in the steelmaking plant is the last process, which completes the transformation from liquid to solid. In the continuous casting process, the molten steel is solidified in the crystallizer. In order to prevent the oxidation of the molten steel and the excessive temperature drop, protective slag needs to be added for heat insulation and heat preservation. However, the protective slag is on the surface of the molten steel, and will be captured by the solidified shell due to the action of electromagnetic stirring. For different casting machines and different electromagnetic stirring equipment, optimization needs to be carried out 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 alternately generated, so that the force acting on the liquid surface pushes the liquid surface to rotate, thereby playing a stirring role.

[0027] However, when the molten steel has high purity and few inclusions, the argon flow rate of the stopper rod does not need to be too high. Generally, the argon in the continuous casting stopper rod is used to prevent inclusions in the molten steel, especially alumina, from accumulating at the nozzle and causing adhesion between the nozzle and the stopper rod; its function is to flush out inclusions. If the argon flow rate is too high, bubbles will adhere to the slab, causing various defects during rolling and resulting in a decrease in slab quality.

[0028] In steelmaking, the purity of molten steel is closely related to the composition of the ladle slag. When the ladle slag composition is suitable, refining can adsorb deoxidation products after deoxidation, preventing these products from remaining in the molten steel and causing excessive inclusions. However, if the ladle slag composition is unsuitable, it will affect the purity of the molten steel, causing nozzle clogging. To reduce clogging, continuous casting increases the argon flow rate in the stopper rod. However, excessive argon flow can cause it to be captured by the billet shell, resulting in defects during cold rolling. If the molten steel purity is high, the argon flow rate can be reduced, and the electromagnetic stirring intensity can be decreased. If the molten steel purity is poor, the argon flow rate needs to be increased, and the electromagnetic stirring intensity needs to be increased. Therefore, effectively judging the purity of molten steel is crucial for adjusting the electromagnetic stirring process in continuous casting.

[0029] This invention utilizes extensive data from the smelting process and cold rolling defects to match the composition of ladle slag with cold rolling defects through data mining. The metallurgical slag system where cold rolling defects occur is defined as the defect occurrence region. When the metallurgical slag composition of molten steel from a subsequent production cycle enters the defect occurrence region, dynamic adjustments are made during the continuous casting process, particularly regarding argon and electromagnetic stirring. For heats in the defect occurrence region, enhanced electromagnetic stirring and high argon flow are implemented. Conversely, the argon flow rate and electromagnetic stirring current can be reduced.

[0030] Therefore, this invention proposes a dynamic adjustment method for electromagnetic stirring based on the correlation between metallurgical slag composition and cold rolling defects, specifically including the following steps:

[0031] S1. Draw a ternary phase diagram of the metallurgical slag composition based on historical data from the continuous casting process (see...). Figure 1 As shown in the figure, the defect area is marked according to the ladle refining slag corresponding to the quality defects of the cold rolled plate during the continuous casting process. The purity of the molten steel is judged according to the distribution of the ladle refining slag in the ternary phase diagram of the metallurgical slag components during the continuous casting process.

[0032] Specifically, first, a ternary phase diagram of the metallurgical slag components is plotted according to historical data in the continuous casting process, the ternary phase diagram of the metallurgical slag components is plotted with a first component, a second component and a third component of 100% by mass as vertices, wherein CaO and MgO are alkaline, Al2O3 and SiO2 are acidic, and FeO is neutral to some extent, so the first component is CaO and MgO, the second component is Al2O3+SiO2, and the third component is FeO, thereby constructing the ternary phase diagram of the metallurgical slag components, then the heats with cold-rolled sheet defects in the continuous casting process and the corresponding ladle refining finished slag are screened out and marked on the ternary phase diagram of the metallurgical slag components, and a defect occurrence region (such as the concentric circle region A in FIG. 1) is plotted thereon; then the ladle refining finished slag is sampled and analyzed in the continuous casting process, and its position is marked in the ternary phase diagram of the metallurgical slag components. When the coordinates of the ladle refining finished slag fall within the defect occurrence region, the purity of the molten steel is defined as “poor”; when the coordinates of the ladle refining finished slag are located on the boundary of the defect occurrence region, the purity of the molten steel is defined as “medium”; and when the coordinates of the ladle refining finished slag fall outside the boundary of the defect occurrence region, the purity of the molten steel is defined as “good”. Figure 1

[0033] S2, dynamically adjusting the argon flow rate according to the purity of the molten steel.

[0034] Specifically, different argon flow rates are matched under different molten steel purity conditions, wherein the argon flow rate is adjusted in the range of 3-18 L / min. Specifically, the argon flow rate is dynamically adjusted according to the purity of the molten steel. When the purity of the molten steel is defined as “good”, the argon flow rate is reduced, when the purity of the molten steel is defined as “poor”, the argon flow rate is increased to flush the accumulation of inclusions at the nozzle and the stopper. Taking the argon flow rate of the stopper as 10 L / min as a reference, when the purity of the molten steel is defined as “poor”, the argon flow rate is increased to 15-18 L / min; when the purity of the molten steel is defined as “medium”, the argon flow rate is adjusted to 8-11 L / min; and when the purity of the molten steel is defined as “good”, the argon flow rate is adjusted to 5-6 L / min.

[0035] S3, dynamically adjusting the stirring current of the electromagnetic stirring according to the purity of the molten steel.

[0036] ​Specifically, the electromagnetic stirring current is dynamically adjusted in combination with different molten steel conditions; when the molten steel purity is defined as "poor", the electromagnetic stirring current intensity is increased to improve the removal effect of inclusions, and when the molten steel purity is defined as "good", the electromagnetic stirring current intensity is reduced to save energy. Taking the electromagnetic stirring current of 500-550 A as a reference, when the molten steel purity is defined as "poor", the stirring current is adjusted to 650-700 A; when the molten steel purity is defined as "medium", the stirring current is adjusted to 500-550 A; and when the molten steel purity is defined as "good", the stirring current is adjusted to 200-300 A.

[0037] By the above method, the cold rolling inclusions (calculated by weight) of the final continuous casting slab are controlled to be less than 5%, so that the slag inclusion defect occurrence rate (calculated by the number of slab blocks) of the continuous casting slab is reduced to less than 3%.

[0038] The method for dynamically adjusting the electromagnetic stirring based on the correlation between the metallurgical slag components and the cold rolling defects will be further described below in combination with specific examples.

[0039] In the following examples, the method for dynamically adjusting the electromagnetic stirring based on the correlation between the metallurgical slag components and the cold rolling defects is used. First, a ternary phase diagram of the metallurgical slag components is plotted according to historical data, and (CaO+MgO)-(Al2O3+SiO2)-FeO is taken as the vertex, wherein CaO+MgO is alkaline, Al2O3+SiO2 is acidic, and FeO is neutral to some extent, a phase diagram of the three endpoints is constructed, and the ladle refining finished slag corresponding to the defective furnace is marked on the ternary phase diagram, and the defect occurrence area (i.e. the concentric circle area A) is plotted on the ternary phase diagram. The concentric circle area A is the refining finished slag, and the rolling defects are tracked in the subsequent process. When rolling defects occur, the slag components of the refining finished slag are marked on the ternary phase diagram, i.e. the defect occurrence area. When a sufficient amount of the concentric circle area A is located, it is the position of the furnace with more cold rolling defects. More cold rolling defects indicate more inclusions in the molten steel. If there are more inclusions in the molten steel, the continuous casting process should be controlled.

[0040] Example 1

[0041] In this example, a furnace of steel is produced in a certain steel plant on a certain day, and the molten steel continuous casting process is adjusted by the following method:

[0042] I. After the steel produced on the day is refined and treated, the ladle slag is sampled and analyzed, and then enters the above-mentioned concentric circle area A. According to the technical scheme, the molten steel purity is defined as "poor". The poor molten steel needs to be stirred intensively, and the argon blowing amount is increased to reduce the plugging of stopper clogging. At the same time, the electromagnetic stirring is intensified.

[0043] II. Adjust argon flow according to the purity of the molten steel. The purity of the molten steel in the furnace is defined as "poor", and the argon flow is increased to 18 L / min based on the argon flow of 10 L / min.

[0044] III. Dynamically adjust the electromagnetic stirring current in combination with different molten steel conditions. When the purity of the molten steel in the furnace is defined as "poor", the stirring intensity needs to be increased to improve the removal effect of inclusions. The electromagnetic stirring current is adjusted to 700 A based on the stirring current of 500-550 A.

[0045] Through the above method, the cold rolling inclusions of the final continuous casting slab (calculated by weight) are controlled to be less than 5%, and the occurrence rate of the continuous casting slab (calculated by the number of slab blocks) is reduced to less than 3%.

[0046] Example 2

[0047] In this embodiment, a furnace of steel is produced in a certain steel plant on a certain day, and the molten steel continuous casting process is adjusted by the following method:

[0048] I. On a certain day, a furnace of steel is produced in a certain steel plant, and the purity of the molten steel is determined according to the actual situation of the molten steel ladle slag. After the steel produced on the day is finished by refining treatment, the ladle slag is sampled and analyzed, and enters the boundary of the above-mentioned concentric circle region A. According to the technical scheme, the purity of the molten steel is defined as "medium". The purity of the molten steel is acceptable, but it has not reached a good level. The argon flow and the electromagnetic stirring intensity of this furnace can be configured according to the medium level.

[0049] II. The argon flow is adjusted to the reference value based on the argon flow of 10 L / min as the reference, and the argon flow of the stopper is controlled to 10 L / min according to the purity of the molten steel being "medium".

[0050] III. The current is adjusted to 500-550 A based on the stirring current of the electromagnetic stirring being 500-550 A, and the purity of the molten steel in the furnace is defined as "medium".

[0051] Through the above method, the cold rolling inclusions of the final continuous casting slab (calculated by weight) are controlled to be less than 5%, and the occurrence rate of the continuous casting slab (calculated by the number of slab blocks) is reduced to less than 3%.

[0052] 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 on the present application, and as long as the variations and modifications of the above described embodiments are within the scope of the spirit of the present application, they will fall within the scope of the claims of the present application.

Claims

1. A method for dynamic adjustment of electromagnetic stirring based on correlation of metallurgical slag components with cold rolling defects, characterized in that, The method comprises the following steps: S1, drawing a ternary phase diagram of metallurgical slag components according to historical data in a continuous casting process, marking a defect occurrence area according to a ladle refining finished slag corresponding to a quality defect of a cold-rolled plate in the continuous casting process, and judging the purity of molten steel according to the distribution of the ladle refining finished slag in the ternary phase diagram of metallurgical slag components; S2, dynamically adjusting argon flow according to the purity of the molten steel; S3, dynamically adjusting stirring current of electromagnetic stirring according to the purity of the molten steel, In the step S1, the ternary phase diagram of metallurgical slag components is drawn with a first component, a second component and a third component as vertices, the first component being CaO+MgO, the second component being Al2O3+SiO2, and the third component being FeO, In the step S1, the purity of the molten steel is judged by the following method: When the coordinates of the ladle refining finished slag fall into the defect occurrence area, the purity of the molten steel is defined as "poor"; When the coordinates of the ladle refining finished slag are located on the boundary of the defect occurrence area, the purity of the molten steel is defined as "medium"; When the coordinates of the ladle refining finished slag fall outside the boundary of the defect occurrence area, the purity of the molten steel is defined as "good", In the step S2, taking the argon flow of a stopper as 10L / min as a reference, when the purity of the molten steel is defined as "poor", the argon flow is increased to 15-18L / min; when the purity of the molten steel is defined as "medium", the argon flow is adjusted to 8-11L / min; and when the purity of the molten steel is defined as "good", the argon flow is adjusted to 5-6L / min, In the step S3, taking the stirring current of electromagnetic stirring as 500-550A as a reference, when the purity of the molten steel is defined as "poor", the stirring current is adjusted to 650-700A; when the purity of the molten steel is defined as "medium", the stirring current is adjusted to 500-550A; and when the purity of the molten steel is defined as "good", the stirring current is adjusted to 200-300A.

2. The method of dynamic adjustment of electromagnetic stirring based on correlation of metallurgical slag components with cold rolling defects according to claim 1, characterized in that, In the step S2, the argon flow is adjusted in the range of 3-18L / min.

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