Method for LF alloying of non-flaw-detection aluminum killed steel of thick slab

Abstract

The invention discloses a thick slab non-flaw detection aluminum killed steel LF alloying method, and belongs to the technical field of ferrous metallurgy. According to the LF, the alloying mode is determined according to the treatment period; the addition amount of aluminum particles is controlled according to acid-soluble aluminum components of the secondary sample after the secondary sample is taken, the end point adjustment of the acid-soluble aluminum components is carried out, the addition amount of the aluminum particles is equal to the product of the target aluminum content and the conversion coefficient range, and the target aluminum content is equal to the finished product aluminum target value-the secondary sample aluminum components + 0.002%; when the treatment period is 25-40 minutes, the conversion coefficient range of the addition amount of the aluminum particles is 5000-9000 kg per ton of steel; when the treatment period is 40-60 minutes, the conversion coefficient range of the addition amount of the aluminum particles is 6000-10000 kg per ton of steel; carrying out wire feeding treatment after LF alloying; the wire feeding amount is controlled according to the calcium-aluminum ratio of 0.1-0.14; the deoxidation alloy consumption during the production of the thick slab non-flaw-detection aluminum killed steel in the LF process is reduced, the smelting cost is reduced, and the comprehensive competitiveness of enterprises is improved.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel metallurgy technology, specifically relating to a method for LF alloying of thick slab non-flaw-detected killed aluminum steel. Background Technology

[0002] As the main process in continuous casting, the LF process is crucial to the overall cost. Since the LF process usually aims for a single aluminum adjustment in the early and middle stages, this operation will result in excessive aluminum loss of high-priced deoxidized alloy aluminum particles during the initial top slag calcium treatment. At the same time, the initial aluminum adjustment inevitably leads to increased contact between molten steel and air during the subsequent argon stirring process, increasing the amount of acid-dissolved aluminum oxidation loss, increasing the loss of deoxidized alloys, and affecting the process cost.

[0003] Therefore, how to reduce the consumption of deoxidation alloys when producing thick slab non-flaw-detected killed aluminum steel in the LF process has become an important issue that urgently needs to be addressed. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide a method for alloying thick slab non-flaw-detected aluminum killed steel using the LF process, thereby reducing the consumption of deoxidizing alloys during the production of thick slab non-flaw-detected aluminum killed steel using the LF process.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides 1. a method for LF alloying of thick slab non-flaw-detected killed aluminum steel, characterized by comprising the following steps: S1: The amount of silicon alloy added during steel tapping in the converter is controlled according to the manganese content of the finished product; S2: After entering the LF furnace, the amount of quicklime in the slag is >0.5kg / ton of steel. The alloying method is determined by the LF furnace according to the processing cycle. After entering the furnace, the top slag is modified. After taking the first sample, the amount of silicon alloy added is controlled according to the silicon composition of the first sample. The amount of silicon alloy added = target silicon content × conversion factor range. The target silicon content = finished product silicon target value - first sample silicon composition. After taking the second sample, the amount of aluminum particles added is controlled according to the acid-soluble aluminum composition of the second sample. The endpoint adjustment of the acid-soluble aluminum composition is carried out. The amount of aluminum particles added = target aluminum content × conversion factor range. The target aluminum content = finished product aluminum target value - second sample aluminum composition + 0.002%. S3: After LF alloying, wire feeding is performed, and the wire feeding amount is controlled according to the calcium-aluminum ratio of 0.1-0.14; S4: After feeding the wire, blow argon cleanly for 5-10 minutes.

[0006] In S4, the standard for argon blowing is that the slag surface is slightly surging and the molten steel is not exposed.

[0007] Among them, thick slab casting machine refers to continuous casting machine with slab thickness ≥250mm and width ≥1650mm; non-destructive steel grade refers to steel grade that does not require vacuum treatment after LF treatment and can be directly cast on the casting machine without the need for internal and external defect detection of the slab; aluminum killed steel refers to steel grade that has aluminum added to molten steel for deoxidation.

[0008] Based on the above technical solution, further, S1 specifically refers to: silicon alloy addition amount = target silicon content × conversion factor range, target silicon content = lower limit of finished silicon - 0.10%; when finished manganese < 1.0%, the conversion factor range is 5.5 kg / ton of steel - 6.5 kg / ton of steel; when finished manganese ≥ 1.0%, the conversion factor range is 7.5 kg / ton of steel - 8.5 kg / ton of steel.

[0009] Based on the above technical solution, further, in S2, when the processing cycle is 25min-40min, 0.2kg / ton steel-0.6kg / ton steel ferrosilicon and 0.2kg / ton steel-0.6kg / ton steel aluminum particles are added after entering the furnace for top slag modification.

[0010] Based on the above technical solution, further, in S2, when the processing cycle is 25min-40min, the conversion factor for the amount of silicon alloy added ranges from 1600kg / ton of steel to 2400kg / ton of steel.

[0011] Based on the above technical solution, further, in S2, when the processing cycle is 25min-40min, the conversion factor for the amount of aluminum particles added ranges from 5000kg / ton of steel to 9000kg / ton of steel.

[0012] Based on the above technical solution, further, in S2, when the processing cycle is 40min-60min, 0.6kg / ton steel-1.4kg / ton steel ferrosilicon is added after entering the furnace for top slag modification.

[0013] Based on the above technical solution, further, in S2, when the processing cycle is 40min-60min, the conversion factor range for the amount of silicon alloy added is 1800kg / ton of steel to 2600kg / ton of steel.

[0014] Based on the above technical solution, further, in S2, when the processing cycle is 40min-60min, the conversion factor for the amount of aluminum particles added ranges from 6000kg / ton of steel to 10000kg / ton of steel.

[0015] Based on the above technical solution, further, in S3, the argon flow rate is controlled during wire feeding to ensure that the diameter of the molten steel turning is between 50mm and 100mm, the blower speed is controlled between 350r / min and 450r / min to maintain a slightly positive pressure atmosphere in the furnace; the wire feeding speed is controlled between 200m / min and 250m / min, and the net argon blowing time is controlled between 5min and 10min.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The LF process of this invention determines the alloying method based on the processing cycle; after taking a secondary sample, the amount of aluminum particles added is controlled according to the acid-soluble aluminum composition of the secondary sample, and the endpoint adjustment of the acid-soluble aluminum composition is performed. The amount of aluminum particles added = target aluminum content × conversion factor range, and the target aluminum content = target value of finished aluminum - aluminum composition of secondary sample + 0.002%; when the processing cycle is 25min-40min, the conversion factor range of the amount of aluminum particles added is 5000kg / ton steel-9000kg / ton steel; when the processing cycle is 40min-60min, the conversion factor range of the amount of aluminum particles added is 6000kg / ton steel-10000kg / ton steel; after LF alloying, wire feeding is performed; the amount of wire feeding is controlled according to a calcium-aluminum ratio of 0.1-0.14; this reduces the consumption of deoxidation alloys when producing non-flaw-detected aluminum killed steel in thick slabs in the LF process, reduces smelting costs, and improves the overall competitiveness of the enterprise.

[0017] 2. By adopting the control method of the present invention, under the premise of ensuring smooth casting before the machine, the average aluminum wire consumption can be reduced by 14.48%-19.31% when LF produces non-flaw-detected aluminum killed steel for thick slabs, and the casting machine casting status is stable. Detailed Implementation

[0018] The present invention will be described in detail below with reference to the embodiments. However, the implementation of the present invention is not limited thereto. Obviously, the embodiments described below are only some embodiments of the present invention. For those skilled in the art, other similar embodiments can be obtained without creative effort and all fall within the protection scope of the present invention.

[0019] Examples 1 to 4 use AH36 steel as the target material and employ the LF alloying method for non-flawless aluminum-killed steel in thick slabs provided by this invention for production. The specific steps are as follows, and the key parameters are shown in Table 1. The processing cycle for Examples 1 and 2 is 25-40 minutes, and the processing cycle for Examples 3 and 4 is 40-60 minutes.

[0020] 1. The amount of silicon alloy added during converter steelmaking is controlled at (finished silicon lower limit - 0.10%) * 7.5 kg / ton of steel - (finished silicon lower limit - 0.10%) * 8.5 kg / ton of steel; 2. After entering the LF (Leading Furnace) process, the amount of slag and quicklime generated is greater than 0.5 kg / ton of steel. The LF process determines different alloying methods based on the processing cycle. The processing cycle is 25-40 minutes. After entering the furnace, 0.25 kg / ton steel - 0.55 kg / ton steel ferrosilicon and 0.25 kg / ton steel - 0.55 kg / ton steel aluminum particles are added for top slag modification. After taking the first sample, the amount of silicon alloy added is controlled according to the silicon composition of the first sample. Ferrosilicon is added at (target value of finished silicon - silicon composition of the first sample) * 1600 kg / ton steel - (target value of finished silicon - silicon composition of the first sample) * 2200 kg / ton steel. After taking the second sample, the amount of aluminum particles added is controlled according to the acid-soluble aluminum composition of the second sample. Aluminum particles are added at (target value of finished aluminum - aluminum composition of the second sample + 0.002%) * 6000 kg / ton steel - (target value of finished aluminum - aluminum composition of the second sample + 0.002%) * 9000 kg / ton steel for the endpoint adjustment of acid-soluble aluminum composition. The processing cycle is 40-60 minutes. After entering the furnace, 0.55 kg / ton steel to 1.25 kg / ton steel ferrosilicon is added for top slag modification. After taking the first sample, the amount of silicon alloy added is controlled according to the silicon composition of the first sample. Ferrosilicon is added at (target value of finished silicon - silicon composition of the first sample) * 1700 kg / ton steel - (target value of finished silicon - silicon composition of the first sample) * 2400 kg / ton steel. After taking the second sample, the amount of aluminum particles added is controlled according to the acid-soluble aluminum composition of the second sample. Aluminum particles are added at (target value of finished aluminum - aluminum composition of the second sample + 0.002%) * 5500 kg / ton steel - (target value of finished aluminum - aluminum composition of the second sample + 0.002%) * 9500 kg / ton steel for final adjustment of the acid-soluble aluminum composition.

[0021] 3. After LF alloying, wire feeding is performed. The argon gas flow rate is controlled during wire feeding to ensure that the diameter of the molten steel turning is between 50mm and 100mm. The blower speed is controlled between 350r / min and 450r / min to maintain a slightly positive pressure atmosphere inside the furnace.

[0022] The wire feeding speed should be controlled between 200m / min and 250m / min, and the wire feeding amount should be controlled according to the calcium-aluminum ratio of 0.1-0.14.

[0023] 4. After feeding the wire, perform a clean argon blowing operation. The clean argon blowing should be performed when the slag surface is slightly surging and the molten steel is not exposed. The clean argon blowing time should be controlled between 5 and 10 minutes.

[0024] Table 1 shows the key parameters for Examples 1 to 4.

[0025]

[0026] The comparative example also uses AH36 steel and is produced using conventional alloying methods. The key parameters are shown in Table 2, and the specific steps are as follows.

[0027] 1. The amount of silicon alloy added during converter steelmaking is controlled at (finished silicon lower limit - 0.10%) * 6.0 kg / ton of steel - (finished silicon lower limit - 0.10%) * 10 kg / ton of steel; 2. The amount of quicklime generated after LF treatment is greater than 0.2 kg / ton of steel. The LF alloying method is not related to the treatment cycle. After entering the furnace, add 0.35 kg / ton steel - 0.85 kg / ton steel aluminum granules for top slag modification. After taking the first sample, control the amount of silicon alloy added according to the silicon composition of the first sample. Add ferrosilicon (finished product silicon target value - first sample silicon composition - 0.02%) * 1600 kg / ton steel - (finished product silicon target value - first sample silicon composition - 0.02%) * 2200 kg / ton steel. Control the amount of aluminum granules added according to the acid-soluble aluminum composition of the first sample. Add aluminum granules (finished product aluminum target value - first sample aluminum composition + 0.002%) * 4000 kg / ton steel - (finished product aluminum target value - first sample aluminum composition + 0.002%) * 7000 kg / ton steel for initial adjustment of acid-soluble aluminum composition. After taking the second sample, the amount of aluminum granules added is controlled according to the aluminum composition of the second sample. The final adjustment of the aluminum composition is achieved by adding aluminum granules at a rate of (target aluminum value of finished product - aluminum composition of second sample) * 5000 kg / ton of steel - (target aluminum value of finished product - aluminum composition of second sample + 0.002%) * 8000 kg / ton of steel. The amount of silicon alloy added is controlled according to the silicon composition of the second sample. The final adjustment of the silicon composition is achieved by adding ferrosilicon at a rate of (target silicon value of finished product - silicon composition of second sample) * 1400 kg / ton of steel - (target silicon value of finished product - silicon composition of first sample) * 2000 kg / ton of steel. 3. After LF alloying, wire feeding is performed. The argon gas flow rate is controlled during wire feeding. There are no quantitative requirements for the diameter of the molten steel turning, and no specific requirements for the fan speed.

[0028] The feeding speed should be controlled between 100m / min and 300m / min, and there is no specific requirement for the calcium-aluminum ratio.

[0029] 4. No argon blowing is required after feeding the wire.

[0030] When producing AH36 steel using the technical solution of this invention, the average consumption of aluminum wire segments per ton of steel is controlled between 1.17 and 1.24 kg / ton of steel; when producing AH36 steel using the comparative technical solution, the average consumption of aluminum wire segments per ton of steel is controlled between 1.45 and 1.55 kg / ton of steel; the technical solution of this invention has a significant cost reduction effect.

[0031] Table 2 shows the key parameters for comparative examples 1 and 2.

[0032]

[0033] Table 3 shows the average steel consumption per ton for aluminum wire segments in Examples 1 to 4 and Comparative Examples 1 and 2.

[0034]

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for LF alloying of thick slab non-flaw-detected killed aluminum steel, characterized in that, Includes the following steps: S1: The amount of silicon alloy added during steel tapping in the converter is controlled according to the manganese content of the finished product; S2: After entering the LF furnace, the amount of quicklime in the slag is >0.5kg / ton of steel. The alloying method is determined by the LF furnace according to the processing cycle. After entering the furnace, the top slag is modified. After taking the first sample, the amount of silicon alloy added is controlled according to the silicon composition of the first sample. The amount of silicon alloy added = target silicon content × conversion factor range. The target silicon content = finished product silicon target value - first sample silicon composition. After taking the second sample, the amount of aluminum particles added is controlled according to the acid-soluble aluminum composition of the second sample. The endpoint adjustment of the acid-soluble aluminum composition is carried out. The amount of aluminum particles added = target aluminum content × conversion factor range. The target aluminum content = finished product aluminum target value - second sample aluminum composition + 0.002%. S3: After LF alloying, wire feeding is performed, and the wire feeding amount is controlled according to the calcium-aluminum ratio of 0.1-0.14; S4: After feeding the wire, blow argon cleanly for 5-10 minutes.

2. The method for LF alloying of thick slab non-flaw-detection killed aluminum steel according to claim 1, characterized in that, Specifically, S1 is: silicon alloy addition amount = target silicon content × conversion factor range, target silicon content = lower limit of finished silicon - 0.10%; when finished manganese < 1.0%, the conversion factor range is 5.5 kg / ton of steel - 6.5 kg / ton of steel; when finished manganese ≥ 1.0%, the conversion factor range is 7.5 kg / ton of steel - 8.5 kg / ton of steel.

3. The method for LF alloying of thick slab non-flaw-detection killed aluminum steel according to claim 1, characterized in that, In step S2, when the processing cycle is 25-40 minutes, 0.2 kg / ton steel - 0.6 kg / ton steel ferrosilicon and 0.2 kg / ton steel - 0.6 kg / ton steel aluminum particles are added after entering the furnace for top slag modification.

4. The method for LF alloying of thick slab non-flaw-detection killed aluminum steel according to claim 3, characterized in that, In S2, when the processing cycle is 25min-40min, the conversion factor for the amount of silicon alloy added ranges from 1600kg / ton of steel to 2400kg / ton of steel.

5. The method for LF alloying of thick slab non-flaw-detection killed aluminum steel according to claim 3, characterized in that, In S2, when the processing cycle is 25min-40min, the conversion factor for the amount of aluminum particles added ranges from 5000kg / ton of steel to 9000kg / ton of steel.

6. The method for LF alloying of thick slab non-flaw-detection killed aluminum steel according to claim 1, characterized in that, In S2, when the processing cycle is 40min-60min, 0.6kg / ton steel to 1.4kg / ton steel ferrosilicon is added after entering the furnace for top slag modification.

7. The method for LF alloying of thick slab non-flaw-detection killed aluminum steel according to claim 6, characterized in that, In S2, when the processing cycle is 40min-60min, the conversion factor for the amount of silicon alloy added ranges from 1800kg / ton of steel to 2600kg / ton of steel.

8. The method for LF alloying of thick slab non-flaw-detection killed aluminum steel according to claim 6, characterized in that, In S2, when the processing cycle is 40min-60min, the conversion factor for the amount of aluminum particles added ranges from 6000kg / ton of steel to 10000kg / ton of steel.

9. The method for LF alloying of thick slab non-flaw-detection killed aluminum steel according to claim 1, characterized in that, In step S3, the argon flow rate is controlled during wire feeding to ensure that the diameter of the molten steel turning is between 50mm and 100mm, the fan speed is controlled between 350r / min and 450r / min, and a slightly positive pressure atmosphere is maintained in the furnace; the wire feeding speed is controlled between 200m / min and 250m / min, and the wire feeding time is controlled between 5min and 10min.

Images