Method for reducing aluminum loss in smelting of cold forging steel

Abstract

The invention belongs to the technical field of smelting of cold heading steel, and particularly discloses a method for reducing aluminum loss in smelting of cold heading steel, which comprises tapping, deoxidizing alloy, blowing argon in an argon blowing station, an LF refining furnace and the like, the tapping temperature, converter slagging alkalinity, converter bottom and ladle bottom argon blowing, ladle slag layer thickness and tapping time are strictly controlled at the tapping position, so that the oxygen content in molten steel is reduced, and the aluminum loss in the molten steel is reduced. No aluminum wire is added in deoxidation alloying, so that the situation that the oxygen content is increased in the process that molten steel enters an argon blowing station from deoxidation alloying, so that the aluminum wire is repeatedly added when the molten steel enters the argon blowing station can be reduced, and in the argon blowing station, the oxygen content in the molten steel is detected for multiple times through an oxygen analyzer, the aluminum wire is added according to the oxygen content, and the molten steel is stirred by adjusting the argon blowing flow after the aluminum wire is fed; according to the method, aluminum wires do not need to be added in the subsequent refining process, the molten steel with the oxygen content determined in the argon blowing station enters the LF refining furnace in a sealed mode, and the problem that in the prior art, aluminum is added for multiple times for deoxidation in the process from tapping deoxidation alloying to refining treatment of smelted cold heading steel, and the aluminum loss is increased is solved.

Description

Technical Field

[0001] The invention relates to the technical field of smelting cold heading steel, and in particular to a method for reducing aluminum loss in smelting cold heading steel. Background Art

[0002] Cold heading steel is a kind of steel that is formed by metal plasticity at room temperature. It is generally divided into low- and medium-carbon high-quality carbon structural steel and high-quality alloy structural steel. It has high cleanliness and good cold heading performance. It is widely used in automobiles, shipbuilding, equipment manufacturing, electronics, home appliances, bicycles, tools, light steel structures, construction and other industries. The smelting process of cold heading steel mainly includes the following steps: molten iron preparation, converter smelting, refining treatment, continuous casting and subsequent treatment. Among them, converter smelting is to pour molten iron into the converter. The core process is to blow oxygen into the molten pig iron to oxidize impurities such as silicon and manganese, release a lot of heat, and increase the temperature in the furnace. This process can decarbonize, dephosphorize, desulfurize and remove inclusions from the molten iron. , as well as adjusting the composition and temperature. During this process, it is necessary to control the blowing time and temperature to ensure the quality of the smelted molten steel. The main technical means include oxygen supply, slag making, heating, adding deoxidizer and alloying operations; the refining treatment is to put the molten steel smelted in the converter into the refining furnace for further refining, and use a specific refining slag system through a strong desulfurization and adsorption capacity of inclusions to reduce the inclusions after calcium treatment, so as to remove more impurities and gases and improve the purity and quality of the molten steel; in the continuous casting stage, by controlling the oxygen activity during the pouring process and feeding aluminum wire and other measures, it is ensured that there are only slight defects in the low-power inspection after continuous casting production, such as shrinkage cavities and central porosity, thereby ensuring the quality of cold heading steel products.

[0003] Due to the changes in temperature and oxygen content in the process of molten steel from converter smelting to continuous casting, aluminum needs to be added multiple times for deoxidation. After the aluminum-iron alloy is added in the deoxidation alloying process of converter smelting, it is necessary to continue to add aluminum with deoxidation effect at the argon blowing station of the refining treatment, and aluminum wire needs to be added according to the oxygen activity control in the continuous casting stage. Although the quality requirements of cold heading steel are met, the multiple additions of aluminum to the molten steel increase the loss of aluminum, thereby increasing the production cost of cold heading steel. Summary of the invention

[0004] The purpose of the present invention is to provide a method for reducing aluminum loss in smelting cold heading steel, so as to solve the problem in the prior art that aluminum is added multiple times for deoxidation during the deoxidation alloying and refining process of smelting cold heading steel, thereby increasing aluminum loss.

[0005] To achieve the above object, the basic scheme provided by the present invention is as follows: S1. Steel tapping: controlling the steel tapping temperature, converter slag basicity, argon blowing at the converter bottom and ladle bottom, ladle slag layer thickness and steel tapping time;

[0006] S2. Deoxidation and alloying: When the molten steel enters the ladle, deoxidizer is added. When the molten steel fills the ladle to 1 / 3, low-carbon ferromanganese and carburizer are added in sequence. When the molten steel fills the ladle to 3 / 4, the addition is completed. No aluminum is added during this process. At this time, the oxygen content range is 25-45ppm;

[0007] S3. Argon blowing treatment: The ladle delivers the molten steel to the argon blowing station, and then connects the argon blowing port on the ladle to blow argon into the molten steel. During the argon blowing process, the oxygen meter measures the oxygen content in the molten steel for multiple times. According to the actual measured oxygen content in the molten steel, the length of the aluminum wire fed into the molten steel is controlled. The time for the argon blowing station to treat the molten steel is controlled at 3-5 minutes.

[0008] S4.LF refining: The molten steel in the argon blowing station is sealed and enters the LF refining furnace. The slag is added into the molten steel in three times. During this process, the electrode power supply gear, argon flow rate and slag adding time of the LF refining furnace are controlled. When the fluidity of the white slag is maintained for not less than 20 minutes, the molten steel can enter the continuous casting stage.

[0009] The principle and beneficial effect of the present invention are as follows: when in use, the steel tapping temperature, converter slag basicity, argon blowing at the converter bottom and ladle bottom, ladle slag layer thickness and steel tapping time are strictly controlled, thereby reducing the oxygen content in the molten steel; no aluminum wire is added during deoxidation and alloying, thereby reducing the increase in oxygen content in the molten steel during the process of entering the argon blowing station from the deoxidation and alloying, resulting in repeated addition of aluminum wire to the molten steel when entering the argon blowing station, thereby reducing aluminum wire consumption; in the argon blowing station, the oxygen content in the molten steel is repeatedly detected by an oxygen meter, aluminum wire is added according to the oxygen content, and the argon blowing flow rate after the aluminum wire is fed is adjusted to stir the molten steel, so that the oxygen in the molten steel fully reacts with the aluminum, and there is no need to add aluminum wire in the subsequent refining process; the oxygen content and the length of the aluminum wire fed are accurately controlled, thereby reducing aluminum loss; the molten steel after oxygen determination at the argon blowing station is sealed and enters the LF refining furnace, thereby reducing the increase in oxygen content in the process of the molten steel entering the LF refining furnace from the argon blowing station.

[0010] Scheme 2 is the preferred basic scheme. In step S1, the tapping temperature is controlled within the range of 1620°C-1650°C, the converter slag basicity is controlled according to R=2.8-3.2, and the converter bottom blowing argon flow rate is 50Nm 3 / h, ladle bottom blowing argon flow rate 60Nm 3 / h, control the thickness of the ladle slag layer ≤100mm, and control the tapping time within 3-6min; by controlling the tapping temperature, the mechanical properties of the cold heading steel can be guaranteed; controlling the converter slag basicity can affect the fluidity of the slag and the protection of the furnace lining; blowing argon at the bottom of the converter and the bottom of the ladle can achieve a uniform chemical composition and temperature of the molten steel, promote the floating of inclusions, remove harmful gases and inclusions, etc.; the thickness of the ladle slag layer can reduce the contact between molten steel and air, prevent secondary oxidation, and protect the quality of molten steel; the tapping time can reduce the waiting time and processing time of molten steel and improve production efficiency.

[0011] Scheme 3 is the preferred basic scheme. In step S2, the amount of deoxidizer added is 0.5-1.5 kg / t, the total amount of low-carbon ferromanganese and silicon-manganese alloy added is 1.6 kg / t, and the amount of carburizer added is 1.6 kg / t. By controlling the material and addition time of the deoxidizing alloy, the purity of the molten steel can be improved, the content of non-metallic inclusions in the molten steel can be reduced, and it can also ensure that the cold heading steel has good cold forging performance and tensile strength.

[0012] Scheme 4 is the preferred basic scheme. In step S3, the oxygen meter is tested twice. The testing steps are as follows:

[0013] 1) Set the target oxygen content range in the oxygen meter, and the initial argon flow rate into the molten steel is 48-64Nm 3 / h;

[0014] 2) The oxygen content in the molten steel is detected for the first time. The oxygen meter controls the length of the aluminum wire fed into the wire feeder according to the oxygen content, and then adjusts the flow rate of argon to 65-80Nm 3 / h;

[0015] 3) After step 1) continues for 2 minutes, the oxygen content in the molten steel is detected for the second time, and the oxygen meter determines whether the oxygen content is within the target oxygen content range. If it is within the target oxygen content range, the refining process is entered. If it is not within the target oxygen content range, the operation of step 2) is entered to increase the length of the fed aluminum wire. By detecting the oxygen content in the molten steel twice, it is convenient to accurately control the oxygen content in the molten steel and the length of the fed aluminum wire, thereby reducing the loss of aluminum wire during the deoxidation process of the molten steel.

[0016] Scheme 5 is a preferred embodiment of Scheme 4, wherein the target oxygen content in step 1) is in the range of 0-10 ppm.

[0017] Option six is ​​a preferred option of option four. In step 2), the diameter of the aluminum wire is 9 mm, the speed of feeding the aluminum wire is 5 m / s, and when the oxygen content is greater than 10 ppm, the length of the feeding aluminum wire increases by 1.1 m for every 1 ppm increase in the oxygen content. This facilitates precise control of the oxygen content in the molten steel and the length of the feeding aluminum wire, thereby reducing the loss of the aluminum wire during the deoxidation of the molten steel.

[0018] Option seven is the preferred option of the basic option. In step S4, the slag material is lime and carbide slag.

[0019] Scheme 8, which is a preferred embodiment of Scheme 7, the steps of controlling the electrode power supply gear, argon flow rate and slag adding time of the LF refining furnace in step S4 are as follows:

[0020] 1) Control the electrode to be 50-100mm away from the molten steel surface, the gear position when the electrode starts to supply power to the molten steel is 5, the amount of lime added is 2.2kg / t, and the flow rate of argon is 30Nm 3 / h, time controlled at 5min;

[0021] 2) After step 1) lasts for 5 minutes, the gear position of the electrode when supplying electricity to the molten steel is adjusted to gear 2, the amount of lime added is 1.1 kg / t, the flow rate of argon gas remains unchanged, and the time is controlled at 5 minutes;

[0022] 3) Step 2) continued for 5 minutes, the gear position of the electrode when supplying electricity to the molten steel remained unchanged, the amount of calcium carbide added was 0.6kg / t, and the argon flow rate was adjusted to 20Nm 3 / h, the time is controlled at 2min, and the fluidity of white slag is maintained for no less than 20 minutes; through strict refining cycle control, the high efficiency and stability of production are ensured to meet the casting cycle requirements of continuous casting. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a flow chart of a method for reducing aluminum loss in smelting cold heading steel. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below through specific embodiments:

[0025] Example

[0026] like Figure 1 As shown: A method for reducing aluminum loss in smelting cold heading steel, comprising the following steps:

[0027] S1. Steel tapping: Control the tapping temperature in the range of 1620-1650℃, the converter slag basicity in the range of R=2.8-3.2, and the converter bottom blowing argon flow rate of 50Nm 3 / h, the ladle bottom blowing argon flow rate is 60Nm 3 / h, ladle slag thickness ≤100mm, tapping time is within 3-6min;

[0028] S2. Deoxidation and alloying: When the molten steel enters the ladle, a deoxidizer is added, and the amount of the deoxidizer added is 0.5-1.5kg / t. When the molten steel fills the ladle to 1 / 3, low-carbon ferromanganese and recarburizer are added in sequence. The total amount of low-carbon ferromanganese and silicon-manganese alloy added is 1.6kg / t, and the amount of recarburizer added is 1.6kg / t. When the molten steel fills the ladle to 3 / 4, the addition is completed. No aluminum is added during this process. At this time, the oxygen content range is 25-45ppm;

[0029] S3. Argon blowing treatment: The ladle delivers the molten steel to the argon blowing station, and then connects the argon blowing port on the ladle to blow argon into the molten steel. During the argon blowing process, the oxygen meter measures the oxygen content in the molten steel twice. According to the actual measured oxygen content in the molten steel, the length of the aluminum wire fed into the molten steel is controlled. The time for the argon blowing station to treat the molten steel is controlled within 3-5 minutes. The specific steps for feeding the aluminum wire into the molten steel are as follows:

[0030] 1) Set the target oxygen content range in the oxygen meter, the target oxygen content range is 0-10ppm, and the initial argon flow rate into the molten steel is 48-64Nm 3 / h;

[0031] 2) Detect the oxygen content in the molten steel for the first time. When the oxygen content is greater than 10ppm, the length of the aluminum wire fed is increased by 1.1m for every 1ppm the oxygen content exceeds, and then adjust the argon flow rate to 65-80Nm 3 / h, where the diameter of the aluminum wire is 9mm and the speed of feeding the aluminum wire is 5m / s;

[0032] 3) After step 1) continues for 2 minutes, the oxygen content in the molten steel is detected for the second time. The oxygen meter determines whether the oxygen content is within the target oxygen content range. If it is within the target oxygen content range, the LF refining process is entered. If it is not within the target oxygen content range, the operation of step 2) is entered to increase the length of the feeding aluminum wire.

[0033] S4.LF refining: The molten steel in the argon blowing station is sealed and enters the LF refining furnace. Slag is added to the molten steel three times. The slag is lime and carbide slag. The steps for controlling the electrode power supply gear, argon flow rate and slag adding time of the LF refining furnace are as follows:

[0034] 1) The electrode is 50-100mm away from the molten steel surface, the gear when the electrode starts to supply power to the molten steel is 5 gears, the amount of lime added is 2.2kg / t, and the flow rate of argon is 30Nm 3 / h, time controlled at 5min;

[0035] 2) After step 1) lasts for 5 minutes, the gear position of the electrode when supplying electricity to the molten steel is adjusted to gear 2, the amount of lime added is 1.1 kg / t, the flow rate of argon gas remains unchanged, and the time is controlled at 5 minutes;

[0036] 3) Step 1) continued for 5 minutes, the gear position of the electrode when supplying electricity to the molten steel remained unchanged, the amount of calcium carbide added was 0.6kg / t, and the argon flow rate was adjusted to 20Nm 3 / h, the time is controlled at 2min, and the fluidity of white slag is maintained for no less than 20 minutes; the molten steel can enter the continuous casting stage.

[0037] The implementation method of this embodiment is as follows: before use, a target oxygen content range is set on the oxygen meter, and the target oxygen content range is 0-10ppm;

[0038] When in use, before tapping, control the tapping temperature of molten steel in the range of 1620-1650℃, the basicity of converter slag in the range of R=2.8-3.2, and the argon flow rate of converter bottom blowing is 50Nm 3 / h, the ladle bottom blowing argon flow rate is 60Nm 3 / h, the thickness of the ladle slag layer is ≤100mm, which can reduce the oxygen content in the molten steel. When tapping, deoxidizer is added when the molten steel enters the ladle, and the amount of deoxidizer added is 0.5-1.5kg / t. When the molten steel fills the ladle to 1 / 3, low-carbon ferromanganese and recarburizer are added in sequence. The total amount of low-carbon ferromanganese and silicon-manganese alloy added is 1.6kg / t, and the amount of recarburizer added is 1.6kg / t. When the molten steel fills the ladle to 3 / 4, the addition is completed. No aluminum is added during this process. At this time, the oxygen content range is 25-45ppm, and the tapping time is controlled within the range of 3-6min. The increase in oxygen content in the molten steel from deoxidation and alloying to the argon blowing station can be reduced, resulting in repeated addition of aluminum wire when the molten steel enters the argon blowing station, thereby reducing aluminum wire consumption and increasing aluminum recovery. The amount of aluminum wire used before and after this method is used is shown in Table 1 below.

[0039] After deoxidation and alloying, the ladle sends the molten steel to the argon blowing station, and then connects the argon blowing port on the ladle to blow argon into the molten steel. The initial flow rate of argon blown into the molten steel is 48-65Nm 3 / h. During the argon blowing process, the oxygen meter detects the oxygen content in the molten steel for the first time. The oxygen meter controls the length of the aluminum wire fed into the wire feeder according to the detected oxygen content. When the oxygen content is greater than 10ppm, the length of the aluminum wire fed is increased by 1.1m for every 1ppm of oxygen content exceeding the limit. At the same time, the flow rate of argon is adjusted to 65-80Nm 3 / h, the oxygen content and the length of the aluminum wire fed can be precisely controlled, thereby reducing aluminum loss.

[0040] The molten steel is sealed and enters the LF refining furnace. Slag is added to the molten steel three times. The slag is lime and carbide slag. The electrode is 50-100mm away from the molten steel surface. The gear when the electrode starts to supply electricity to the molten steel is 5 gears, and the argon flow rate is 30Nm 3 / h, the amount of lime added is 2.2kg / , after 5 minutes, the gear during power supply is adjusted to gear 2, the amount of lime added is 1.1kg / t, the argon flow rate remains unchanged, after 5 minutes, the gear during power supply remains unchanged, the amount of calcium carbide added is 0.6kg / t, and the argon flow rate is adjusted to 20Nm 3 / h, observe the fluidity of the white slag after 2 minutes, and maintain the fluidity of the white slag for no less than 20 minutes. The molten steel can enter the continuous casting stage.

[0041] Addition amount (kg / t) Steel grade aluminum content (%) AL yield (%) Before use 3.68 0.039 26.49 After use 1.04(1000m) 0.039 38.24

[0042] Table 1

[0043] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for reducing aluminum loss in smelting cold heading steel, characterized in that: The following steps are involved: S1. Steel tapping: Control the steel tapping temperature, converter slag basicity, argon blowing at the converter bottom and ladle bottom, ladle slag layer thickness and steel tapping time; S2. Deoxidation and alloying: When the molten steel enters the ladle, a deoxidizer is added. When the molten steel fills the ladle to 1 / 3, low-carbon ferromanganese and a carburizer are added in sequence. When the molten steel fills the ladle to 3 / 4, the addition is completed. No aluminum is added during this process. At this time, the oxygen content is 25-45ppm; S3. Argon blowing treatment: The ladle delivers the molten steel to the argon blowing station, and then connects the argon blowing port on the ladle to blow argon into the molten steel. During the argon blowing process, the oxygen content in the molten steel is measured by the oxygen meter for multiple times. According to the actual measured oxygen content in the molten steel, the length of the aluminum wire fed into the molten steel is controlled. The time for the argon blowing station to treat the molten steel is controlled within 3-5 minutes; S4.LF refining: The molten steel treated with argon blowing in S3 is sealed and enters the LF refining furnace, and the slag is added into the molten steel in three times. During this process, the electrode power supply gear, argon flow rate and slag adding time of the LF refining furnace are controlled. When the fluidity of the white slag is maintained for not less than 20 minutes, the molten steel can enter the continuous casting stage.

2. A method for reducing aluminum loss in cold heading steel according to claim 1, characterized in that In step S1, the tapping temperature is controlled within the range of 1620-1650°C, the converter slag basicity is controlled according to R=2.8-3.2, and the converter bottom blowing argon flow rate is 50Nm 3 / h, ladle bottom blowing argon flow rate 60Nm 3 / h, control the ladle slag layer thickness ≤100mm, and the steel tapping time is controlled within 3-6min.

3. The method for reducing aluminum loss in cold heading steel according to claim 1, characterized in that: In step S2, the amount of deoxidizer added is 0.5-1.5 kg / t, the total amount of low carbon ferromanganese and silicon manganese alloy added is 1.6 kg / t, and the amount of recarburizer added is 1.6 kg / t.

4. The method for reducing aluminum loss in smelting cold heading steel according to claim 1, characterized in that: In step S3, the oxygen meter is tested twice, and the testing steps are as follows: 1) Set the target oxygen content range in the oxygen meter, and the initial argon flow rate into the molten steel is 48-64Nm 3 / h; 2) The oxygen content in the molten steel is detected for the first time. The oxygen meter controls the length of the aluminum wire fed into the wire feeder according to the oxygen content, and then adjusts the flow rate of argon to 65-80Nm 3 / h; 3) After step 1) continues for 2 minutes, the oxygen content in the molten steel is detected for the second time. The oxygen meter determines whether the oxygen content is within the target oxygen content range. If it is within the target oxygen content range, the refining process is entered. If it is not within the target oxygen content range, the operation of step 2) is performed to increase the length of the feeding aluminum wire.

5. A method for reducing aluminum loss in cold heading steel according to claim 4, characterized in that ,The target oxygen content range in step 1) is 0-10ppm.

6. A method for reducing aluminum loss in smelting cold heading steel according to claim 4, characterized in that: In step 2), the diameter of the aluminum wire is 9 mm, the speed of feeding the aluminum wire is 5 m / s, and when the oxygen content is greater than 10 ppm, the length of the feeding aluminum wire increases by 1.1 m for every 1 ppm exceeding the oxygen content.

7. The method for reducing aluminum loss in cold heading steel according to claim 1, characterized in that: The slag materials in step S4 are lime and carbide slag.

8. A method for reducing aluminum loss in smelting cold heading steel according to claim 7, characterized in that: The steps of controlling the electrode power supply gear, argon flow rate and slag adding time of the LF refining furnace in step S4 are as follows: 1) Control the electrode to be 50-100mm away from the molten steel surface, the gear position when the electrode starts to supply power to the molten steel is 5, the amount of lime added is 2.2kg / t, and the flow rate of argon is 30Nm 3 / h; 2) After step 1) lasts for 5 minutes, the gear position of the electrode supplying electricity to the molten steel is adjusted to gear 2, the amount of lime added is 1.1 kg / t, and the flow rate of argon gas remains unchanged; 3) Step 2) continued for 5 minutes, the gear position of the electrode when supplying electricity to the molten steel remained unchanged, the amount of calcium carbide added was 0.6kg / t, and the argon flow rate was adjusted to 20Nm 3 / h, the time is controlled at 2min, and the fluidity of the white slag is maintained for no less than 20 minutes.

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