Aluminum addition method for LF refining of high-aluminum steel, high-aluminum steel obtained by the method and application of the high-aluminum steel

Abstract

The application provides a LF refining aluminum adding method for high-aluminum steel, obtained high-aluminum steel and application thereof, and comprises the following steps: refining converter molten steel in an LF furnace, then adding a slagging agent into a ladle of the LF furnace to perform slagging treatment, and obtaining a refining slag; continuously adding aluminum wires into the molten steel in the ladle, and stirring the molten steel during the adding process; after the adding of the aluminum wires is completed, performing soft blowing treatment on the molten steel; the adding depth of the aluminum wires is 0.6-0.75 times of the depth of the molten steel under the molten steel liquid surface; according to the analysis result of the composition of the molten steel, the aluminum wires are selectively supplemented to control the aluminum content in the molten steel to reach a target range, and then a tapping operation is performed. The method is simple, convenient to operate, high in production efficiency, and suitable for industrialized scale production.

Description

Technical Field

[0001] This invention relates to the field of iron and steel smelting technology, and in particular to a method for adding aluminum in the LF refining of high-alumina steel, the resulting high-alumina steel, and its applications. Background Technology

[0002] High-alumina steel typically refers to steel grades with an aluminum content of ≥1%. Due to its superior properties such as high yield strength, high tensile strength, good ductility, and low density, it shows broad application prospects in fields such as automotive lightweighting, engineering machinery, and marine engineering. With the deepening of the "dual-carbon" strategy and the green transformation and upgrading of the manufacturing industry, the market demand for high-alumina steel, as a key material for achieving equipment lightweighting, continues to grow. However, because the density of aluminum is much lower than that of molten steel, and aluminum is chemically reactive and easily oxidized, precise control of the aluminum content during the smelting process of high-alumina steel is difficult, restricting the stable production of high-alumina steel.

[0003] In existing technologies, the addition of aluminum in the production of high-alumina steel mainly adopts the aluminum block feeding method and the wire feeding method. The aluminum block feeding method involves directly adding aluminum blocks or ingots into the ladle or furnace. During the feeding process, molten steel splashes severely, the aluminum blocks melt unevenly, and the aluminum content is easily too high or too low in some areas, resulting in poor stability of composition control. In addition, aluminum readily reacts violently with oxides in molten steel and slag, seriously reducing the purity of molten steel. The wire feeding method often uses single wires or small coils of aluminum wire to be added in batches, which has the problems of long wire feeding time, low production efficiency, and large aluminum wire oxidation loss. It is difficult to meet the requirements of stable and efficient production of high-alumina steel. Based on this, the present invention provides a method for adding aluminum in LF refining of high-alumina steel, the resulting high-alumina steel and its applications, to solve the problems of low aluminum yield and difficulty in precise control of aluminum content in the existing high-alumina steel smelting process. Summary of the Invention

[0004] The main objective of this invention is to provide a method for adding aluminum in the LF refining of high-aluminum steel, the resulting high-aluminum steel, and its applications, aiming to solve the technical problems of low aluminum yield and difficulty in accurately controlling aluminum content in the existing high-aluminum steel smelting process.

[0005] To achieve the above objectives, the present invention provides a method for adding aluminum in the LF refining of high-alumina steel, comprising the following steps: The molten steel from the converter is refined in the LF furnace, and then a slagging agent is added to the ladle of the LF furnace for slagging treatment to obtain refined slag.

[0006] Aluminum wire is continuously added to the molten steel in the ladle, and the molten steel is stirred during the addition process; after the aluminum wire is added, the molten steel is subjected to soft blowing treatment.

[0007] The aluminum wire is added to a depth of 0.6 to 0.75 times the depth of the molten steel below the surface of the molten steel.

[0008] Based on the analysis results of the molten steel composition, aluminum wire is selectively added to control the aluminum content in the molten steel to reach the target range before tapping.

[0009] According to an embodiment of this application, the aluminum wire is added at the center of the ladle.

[0010] The aluminum wire is added at a speed of 3~4 m / s.

[0011] The diameter of the aluminum wire is 9~12mm.

[0012] According to an embodiment of this application, the stirring of molten steel during the addition process is carried out by bottom blowing argon gas.

[0013] The bottom-blown argon flow rate is 100~200 NL / min.

[0014] According to an embodiment of this application, the soft-blowing treatment includes soft-blowing argon gas treatment.

[0015] The flow rate of the soft-blown argon gas is 30~50 NL / min.

[0016] The duration of soft blowing treatment is ≥5 minutes.

[0017] According to embodiments of this application, the slag-forming agent includes lime and pre-melted slag.

[0018] The amount of lime added is 4~7 kg / t of molten steel.

[0019] The amount of pre-melted slag added is 0.5~2 kg / t of molten steel.

[0020] The sum of FeO and MnO content in the refining slag is ≤1.0%.

[0021] According to the embodiments of this application, the temperature of the molten steel in the converter is 1580~1620℃.

[0022] The temperature of the molten steel during the refining process is 1590~1630℃.

[0023] The refining time is ≥32 minutes.

[0024] According to an embodiment of this application, the target range for controlling the aluminum content in the molten steel is 3.0~4.5%.

[0025] The temperature of the molten steel being tapped is 1610~1630℃.

[0026] The present invention also provides a high-alumina steel, which is prepared by the LF refining aluminum addition method for high-alumina steel as described above.

[0027] According to an embodiment of this application, the aluminum content in the high-aluminum steel is 3.0~4.5%.

[0028] The sulfur content in the high-alumina steel is ≤0.003%.

[0029] The aluminum yield in the high-aluminum steel is ≥88%.

[0030] The present invention also provides an application of the above-mentioned high-alumina steel, namely, the application of the high-alumina steel in the preparation of high-alumina TRIP steel, high-alumina electrical steel, high-alumina mold steel, high-alumina steel sheet for automobiles or high-alumina steel sheet for engineering machinery.

[0031] Compared with the prior art, the beneficial effects of the present invention are: The aforementioned LF refining aluminum addition method for high-alumina steel, the resulting high-alumina steel, and its applications, through precise control of the aluminum wire addition depth, effectively avoids aluminum oxidation and burn-off caused by shallow addition, as well as the problems of violent steel splashing and slag entrapment caused by excessive addition. This significantly improves aluminum yield and reduces alloy consumption costs. Furthermore, the adoption of a process combining continuous aluminum addition with dynamic stirring, coupled with a closed-loop control strategy of component analysis-selective addition, achieves refined control of aluminum content, effectively solving the technical challenges of large fluctuations in aluminum content and low target hit rate in high-alumina steel smelting, ensuring that the aluminum content of molten steel consistently reaches the target range. Slag formation to create a refining slag layer, along with stirring and subsequent soft blowing during aluminum addition, promotes the flotation and removal of inclusions, reducing inclusion formation caused by aluminum addition and improving the cleanliness of the high-alumina steel. Through the synergy of these process steps, the technical challenges of low aluminum yield and difficulty in aluminum content control in existing high-alumina steel smelting are effectively solved, demonstrating good market prospects and application value.

[0032] Moreover, the method of the present invention is simple, easy to operate, and has high production efficiency, making it suitable for industrial-scale production. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0034] Figure 1 This is a process flow diagram of adding aluminum wire in Embodiment 1 of the present invention.

[0035] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] The technical solutions of the various embodiments of the present invention can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0038] To achieve the above objectives, the present invention provides a method for adding aluminum in the LF refining of high-alumina steel, comprising the following steps: S1: The molten steel from the converter is refined in the LF furnace, and then a slag-forming agent is added to the ladle of the LF furnace for slag formation treatment to obtain refined slag.

[0039] In some embodiments, by adding a slag-forming agent after refining in an LF furnace, a reducing slag system with high basicity and low oxidizing properties is formed, which effectively reduces the total content of FeO and MnO in the refining slag, creates a low oxygen potential environment for subsequent aluminum addition, and reduces the oxidation loss of aluminum; it can also promote the removal of dissolved oxygen and impurities such as sulfur and phosphorus in the molten steel, and improve the cleanliness of the molten steel.

[0040] In some embodiments, slag formation treatment makes the temperature and composition fields inside the ladle more uniform, providing a stable physicochemical environment for the subsequent addition of aluminum wire.

[0041] S2: Continuously add aluminum wire to the molten steel in the ladle and stir the molten steel during the addition process; after the aluminum wire is added, perform soft blowing treatment on the molten steel.

[0042] The aluminum wire is added to a depth of 0.6 to 0.75 times the depth of the molten steel below the surface of the molten steel.

[0043] In some embodiments, the precise control of the aluminum wire addition depth allows the aluminum wire to fully melt under the static pressure of the molten steel, avoiding oxidation loss caused by the aluminum wire coming into contact with air or slag layer, and significantly improving the aluminum element recovery rate. Stirring the molten steel during the continuous addition of aluminum wire can promote the rapid diffusion and uniform distribution of aluminum elements in the molten steel, prevent local aluminum content from being too high or too low, and ensure composition uniformity.

[0044] In some embodiments, soft blowing treatment utilizes the weak stirring effect of an inert gas (such as argon) to promote the floating and removal of deoxidation products and inclusions, while avoiding slag entrapment and secondary oxidation caused by strong stirring, thereby further improving the cleanliness of molten steel.

[0045] In some embodiments, by adjusting the depth of aluminum wire addition and controlling the intensity of stirring the molten steel, the splashing of molten steel caused by violent reaction during the addition of aluminum wire can be effectively suppressed, ensuring operational safety.

[0046] In some embodiments, an automatic wire feeding device is used to continuously add whole coils of aluminum wire into the ladle. Adding the aluminum wire in whole coils can reduce aluminum wire oxidation loss and increase the aluminum yield to over 88%. The aluminum content control accuracy is high, with a hit rate of over 95%. The Al2O3 inclusions in the molten steel are reduced, and the purity of the molten steel is improved. Production efficiency is improved, the wire feeding time is shortened by more than 30%, and the operating environment is improved, with less molten steel splashing.

[0047] In some embodiments, the aluminum wire is added to a depth of 0.7 to 0.75 times the depth of the molten steel below the surface of the molten steel.

[0048] In some embodiments, the aluminum wire is added to a depth of 0.6 to 0.7 times the depth of the molten steel below the surface of the molten steel.

[0049] S3: Based on the analysis results of the molten steel composition, selectively add the aluminum wire to control the aluminum content in the molten steel to reach the target range before proceeding with the tapping operation.

[0050] In some embodiments, aluminum wire is selectively added based on the analysis results of the molten steel composition to achieve precise fine-tuning of the aluminum content, ensuring that the final aluminum content is strictly controlled within the target range and meeting the requirements of high-aluminum steel for aluminum content; at the same time, it can also avoid alloy waste caused by excessive addition at one time and reduce production costs.

[0051] In some embodiments, by optimizing the depth of aluminum wire addition, the slag-making process, and the synergistic coordination of stirring, the oxidation loss of aluminum is minimized. Compared with traditional addition methods, the aluminum yield is increased by 10-20%, significantly reducing alloy costs. By adopting a two-stage aluminum wire addition method of "main addition and selective supplementation" combined with process analysis feedback, the control accuracy of aluminum content in molten steel is improved to within ±0.005%, meeting the stringent requirements of high-aluminum steel for aluminum content.

[0052] The aforementioned LF refining aluminum addition method for high-alumina steel effectively avoids aluminum oxidation and burn-off caused by shallow addition, and severe steel splashing and slag entrapment caused by excessive addition, by precisely controlling the depth of aluminum wire addition. This significantly improves aluminum yield and reduces alloy consumption costs. Furthermore, the method combines continuous aluminum addition with dynamic stirring, along with a closed-loop control strategy of component analysis and selective addition, achieving precise control of aluminum content. This effectively solves the technical challenges of large aluminum content fluctuations and low target hit rate in high-alumina steel smelting, ensuring that the aluminum content of the molten steel consistently reaches the target range. Slag formation creates a refining slag layer, and stirring and subsequent soft blowing during aluminum addition promote the flotation and removal of inclusions, reducing inclusion formation caused by aluminum addition and improving the cleanliness of the high-alumina steel. Through the synergy of these process steps, the technical challenges of low aluminum yield and difficulty in aluminum content control in existing high-alumina steel smelting are effectively solved, demonstrating good market prospects and application value.

[0053] In some embodiments, the aluminum wire is placed at the center of the ladle.

[0054] The speed at which the aluminum wire is added is 3~4 m / s; The diameter of the aluminum wire is 9~12mm.

[0055] In some embodiments, the rate at which the aluminum wire is added is 3.2 to 4 m / s.

[0056] The diameter of the aluminum wire is 10~12mm.

[0057] In some embodiments, aluminum wire is added from the center of the ladle. Taking advantage of the fact that the temperature is highest and the convection is strongest in the central region of the ladle, the melting path of the aluminum wire in the molten steel is extended, ensuring that the aluminum wire is completely melted before contacting the ladle wall or slag layer, thus avoiding the accumulation of unmelted aluminum blocks in some areas.

[0058] In some embodiments, adjusting the rate at which aluminum wire is added can give the aluminum wire sufficient kinetic energy to quickly penetrate the slag layer and enter the molten steel, reducing the residence time in the high-temperature slag layer and inhibiting the pre-oxidation of aluminum; and by matching a suitable aluminum wire diameter, the aluminum wire can begin to melt just when it reaches the target depth, avoiding slag layer oxidation caused by too low a speed or violent splashing of molten steel caused by too high a speed.

[0059] In some embodiments, a moderate rate of aluminum wire feeding can ensure continuous and stable aluminum wire feeding, prevent wire breakage or blockage caused by speed fluctuations, and ensure smooth process operation.

[0060] In some embodiments, the stirring of the molten steel during the addition process is carried out by bottom blowing argon gas.

[0061] The bottom-blown argon flow rate is 100~200 NL / min.

[0062] In some embodiments, the bottom-blown argon flow rate is 150~200 NL / min.

[0063] In some embodiments, bottom-blown argon gas forms a rising bubble column at the bottom of the ladle, driving the molten steel to generate a circulating motion, forming a synergistic flow field with the aluminum wire added in the center, accelerating the diffusion and uniform distribution of aluminum in the molten steel, and shortening the mixing time; argon gas stirring can promote temperature uniformity inside the ladle, eliminate the low-temperature zone at the bottom, ensure that the aluminum wire is in the optimal melting temperature range at the target depth, and improve melting efficiency.

[0064] In some embodiments, a suitable bottom-blown argon flow rate ensures sufficient fluid kinetic energy to promote the collision and aggregation of inclusions, while avoiding the exposure of molten steel and slag entrapment caused by excessive stirring, thus achieving the pre-floating of deoxidation products. Moreover, continuous bottom-blown stirring can prevent the explosive generation of Al2O3 inclusions caused by excessively high local aluminum content, thereby reducing the generation of large inclusions.

[0065] In some embodiments, the soft-blowing process includes soft-blowing argon treatment.

[0066] The flow rate of the soft-blown argon gas is 30~50 NL / min.

[0067] The duration of soft blowing treatment is ≥5 minutes.

[0068] In some embodiments, the soft-blown argon flow rate is 35~50 NL / min.

[0069] The soft blowing treatment lasts for 5 to 15 minutes.

[0070] In some embodiments, the duration of the soft blowing treatment is 8 to 12 minutes.

[0071] In some embodiments, the use of low-flow-rate inert argon gas stirring during the soft blowing stage can promote the further polymerization and growth of deoxidation products such as Al2O3 and their floating to the slag layer, thereby reducing the inclusion content in the steel. The low soft blowing argon gas flow rate can prevent the molten steel from being exposed and the slag layer from being entrained, protect the aluminum element recovery rate, and maintain the high cleanliness of the molten steel.

[0072] In some embodiments, the slag-forming agent includes lime and pre-melted slag.

[0073] The amount of lime added is 4~7 kg / t of molten steel.

[0074] The amount of pre-melted slag added is 0.5~2 kg / t of molten steel.

[0075] The sum of FeO and MnO content in the refining slag is ≤1.0%.

[0076] In some embodiments, the amount of lime added is 4~6 kg / t of molten steel.

[0077] The amount of pre-melted slag added is 1.5~2 kg / t of molten steel.

[0078] In some embodiments, lime and pre-melted slag are added to the ladle. The amount of lime added is 4~7 kg / t steel, and the amount of pre-melted slag added is 0.5~1 kg / t steel. The slag is melted by electric heating to form white slag, which is the obtained refining slag.

[0079] In some embodiments, the temperature of the molten steel in the converter is 1580~1620℃.

[0080] The temperature of the molten steel during the refining process is 1590~1630℃.

[0081] The refining time is ≥32 minutes.

[0082] In some embodiments, the temperature of the molten steel in the converter is 1605~1620℃.

[0083] The temperature of the molten steel during the refining process is 1600~1620℃.

[0084] The refining time is 32-45 minutes.

[0085] In some embodiments, after the converter tapps the steel, the molten steel enters the LF ladle refining furnace, and the temperature of the molten steel in the converter is controlled at 1580~1620℃, and the net height of the ladle is ≥500mm.

[0086] In some embodiments, the clear height of the ladle is 550~650mm.

[0087] In some embodiments, the target range for controlling the aluminum content in the molten steel is 3.0 to 4.5%.

[0088] The temperature of the molten steel being tapped is 1610~1630℃.

[0089] In some embodiments, the temperature of the molten steel being tapped is 1610~1625℃.

[0090] The present invention also provides a high-alumina steel, which is prepared by the above-described LF refining aluminum addition method for high-alumina steel.

[0091] In some embodiments, the aluminum content in the high-aluminum steel is 3.0 to 4.5%.

[0092] The sulfur content in the high-alumina steel is ≤0.003%.

[0093] The aluminum yield in the high-aluminum steel is ≥88%.

[0094] The present invention also provides an application of the above-mentioned high-alumina steel, namely, the application of the high-alumina steel in the preparation of high-alumina TRIP steel, high-alumina electrical steel, high-alumina mold steel, high-alumina steel sheet for automobiles or high-alumina steel sheet for engineering machinery.

[0095] In some embodiments, the application of the high-alumina steel obtained by the present invention is not specifically limited. For example, the method of the present invention can be applied to a converter-LF refining-RH refining-continuous casting process, and is suitable for refining ladles of 150~300t.

[0096] To further illustrate the present invention, the following examples are provided: Example 1 A method for adding aluminum in the LF refining of high-aluminum steel with an aluminum content of 3.5% is described in [reference needed]. Figure 1 The steps are as follows: S1: The molten steel from the converter is refined in a 210t LF furnace. Then, a slagging agent is added to the ladle of the LF furnace for slagging treatment to obtain refined slag. 840kg of lime (4kg / t molten steel) and 210kg of pre-melted slag (1kg / t molten steel) are added to the ladle. The total content of FeO and MnO in the refined slag is controlled to be ≤1.0%. The temperature of the molten steel in the converter is 1605℃, and the net height of the ladle is 600mm. During the refining process, the temperature of the molten steel is 1620℃, and the refining time is 35min.

[0097] S2: An automatic wire feeding device is used to continuously add aluminum wire to the molten steel in the ladle, and the molten steel is stirred during the addition process by bottom blowing argon gas at a flow rate of 150 NL / min. After the aluminum wire is added, the molten steel is subjected to soft blowing treatment with soft blowing argon gas at a flow rate of 40 NL / min for 8 minutes. The depth of the aluminum wire added is 0.7 times the depth of the molten steel below the surface. The aluminum wire is added at the center of the ladle at a speed of 3.5 m / s. The diameter of the aluminum wire is 10 mm. The amount of aluminum wire added is calculated based on a target aluminum content of 3.5%, an aluminum recovery rate of 90%, and a total mass of 735 kg of aluminum wire added.

[0098] S3: Sampling and analysis of the molten steel composition showed an aluminum content of 3.48%, which meets the target requirements. No additional aluminum wire is needed. The steel was then tapped at a temperature of 1615℃.

[0099] Tests showed that the high-aluminum steel with an aluminum content of 3.5% contained 3.48% aluminum and 0.001% sulfur, with an aluminum recovery rate of 90%, and the molten steel was of qualified quality.

[0100] Example 2 A method for adding aluminum in the LF refining of high-aluminum steel with an aluminum content of 4.0% includes the following steps: S1: The molten steel from the converter is refined in a 210t LF furnace. Then, a slagging agent is added to the ladle of the LF furnace for slagging treatment to obtain refined slag. 1050kg of lime (5kg / t molten steel) and 315kg of pre-melted slag (1.5kg / t molten steel) are added to the ladle. The total content of FeO and MnO in the refined slag is controlled to be ≤0.5%. The temperature of the molten steel in the converter is 1610℃, and the net height of the ladle is 550mm. During the refining process, the temperature of the molten steel is 1600℃, and the refining time is 40min.

[0101] S2: An automatic wire feeding device is used to continuously add aluminum wire to the molten steel in the ladle, and the molten steel is stirred during the addition process by bottom blowing argon gas at a flow rate of 180 NL / min. After the aluminum wire is added, the molten steel is subjected to soft blowing treatment with soft blowing argon gas at a flow rate of 35 NL / min for 10 minutes. The depth of the aluminum wire added is 0.65 times the depth of the molten steel below the surface. The aluminum wire is added at the center of the ladle at a speed of 3.2 m / s. The diameter of the aluminum wire is 11 mm. The amount of aluminum wire added is calculated based on a target aluminum content of 4.0%, the aluminum recovery rate is 92%, and the mass of the added aluminum wire is 913 kg.

[0102] S3: Sampling and analysis of the molten steel composition showed an aluminum content of 3.95%. 50 kg of aluminum wire was added, bringing the final target aluminum content to 4.02%. The steel was then tapped at a temperature of 1610℃.

[0103] Tests showed that the high-aluminum steel with an aluminum content of 4% contained 4.02% aluminum and 0.002% sulfur. The aluminum recovery rate in the high-aluminum steel was 92%, and the molten steel quality was qualified.

[0104] Example 3 A method for adding aluminum in the LF refining of high-aluminum steel with an aluminum content of 4.5% includes the following steps: S1: The molten steel from the converter is refined in a 210t LF furnace. Then, a slagging agent is added to the ladle of the LF furnace for slagging treatment to obtain refined slag. 1260kg of lime (6kg / t molten steel) and 420kg of pre-melted slag (2kg / t molten steel) are added to the ladle. The total content of FeO and MnO in the refined slag is controlled to be ≤0.3%. The temperature of the molten steel in the converter is 1620℃, and the net height of the ladle is 650mm. During the refining process, the temperature of the molten steel is 1610℃, and the refining time is 45min.

[0105] S2: An automatic wire feeding device is used to continuously add aluminum wire to the molten steel in the ladle, and the molten steel is stirred during the addition process using bottom blowing argon gas at a flow rate of 200 NL / min. After the aluminum wire is added, the molten steel undergoes soft blowing treatment using argon gas at a flow rate of 50 NL / min for 12 minutes. The depth of the aluminum wire added is 0.75 times the depth of the molten steel below the surface. The aluminum wire is added at the center of the ladle at a speed of 4.0 m / s. The diameter of the aluminum wire is 12 mm. The amount of aluminum wire added is calculated based on a target aluminum content of 4.5%, with an aluminum recovery rate of 88%, and the mass of the added aluminum wire is 1074 kg.

[0106] S3: Sampling and analysis of the molten steel composition showed an aluminum content of 4.45%. 45 kg of aluminum wire was added, bringing the final target aluminum content to 4.52%. The steel was then tapped at a temperature of 1625℃.

[0107] Tests showed that the high-aluminum steel with an aluminum content of 4.5% contained 4.52% aluminum and 0.001% sulfur, with an aluminum recovery rate of 88%, and the molten steel was of qualified quality.

[0108] Comparative Example 1 High-alumina steel with 3.5% aluminum content was produced using the traditional aluminum block addition method. The aluminum blocks were added in four stages, with each stage followed by stirring with 600 NL / min argon gas for 2 minutes before being fused to the steel via LF furnace electrodes. The aluminum yield was 75%, the aluminum content hit rate was 80%, and the Al2O3 inclusion content in the molten steel was relatively high.

[0109] Table 1 shows the data for producing high-aluminum steel with 3.5% aluminum using the LF refining aluminum addition method of the present invention and the traditional aluminum block addition method.

[0110] Table 1. Data on the production of high-alumina steel with 3.5% aluminum content using the method of the present invention and the traditional aluminum block addition method. The comparison shows that the method of the present invention is superior to the traditional aluminum block addition method in terms of aluminum yield, aluminum content control accuracy, molten steel purity and production efficiency, and has significant technological progress and economic benefits.

[0111] The aforementioned LF refining aluminum addition method for high-alumina steel, the resulting high-alumina steel, and its applications, through precise control of the aluminum wire addition depth, effectively avoids aluminum oxidation and burn-off caused by shallow addition, as well as the problems of violent steel splashing and slag entrapment caused by excessive addition. This significantly improves aluminum yield and reduces alloy consumption costs. Furthermore, the adoption of a process combining continuous aluminum addition with dynamic stirring, coupled with a closed-loop control strategy of component analysis-selective addition, achieves refined control of aluminum content, effectively solving the technical challenges of large fluctuations in aluminum content and low target hit rate in high-alumina steel smelting, ensuring that the aluminum content of molten steel consistently reaches the target range. Slag formation to create a refining slag layer, along with stirring and subsequent soft blowing during aluminum addition, promotes the flotation and removal of inclusions, reducing inclusion formation caused by aluminum addition and improving the cleanliness of the high-alumina steel. Through the synergy of these process steps, the technical challenges of low aluminum yield and difficulty in aluminum content control in existing high-alumina steel smelting are effectively solved, demonstrating good market prospects and application value.

[0112] Moreover, the method of the present invention is simple, easy to operate, and has high production efficiency, making it suitable for industrial-scale production.

[0113] In summary, the above-described technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for adding aluminum in the LF refining of high-alumina steel, characterized in that, Including the following steps: S1: The molten steel from the converter is refined in the LF furnace, and then a slag-forming agent is added to the ladle of the LF furnace for slag formation treatment to obtain refined slag. S2: Continuously add aluminum wire to the molten steel in the ladle and stir the molten steel during the addition process; after the aluminum wire is added, perform soft blowing treatment on the molten steel; The aluminum wire is added to a depth of 0.6 to 0.75 times the depth of the molten steel below the surface of the molten steel. S3: Based on the analysis results of the molten steel composition, selectively add the aluminum wire to control the aluminum content in the molten steel to reach the target range before proceeding with the tapping operation.

2. The method for adding aluminum in the LF refining of high-alumina steel according to claim 1, characterized in that, The aluminum wire is added at the center of the ladle. The speed at which the aluminum wire is added is 3~4 m / s; The diameter of the aluminum wire is 9~12mm.

3. The method for adding aluminum in the LF refining of high-alumina steel according to claim 1, characterized in that, The stirring of the molten steel during the addition process is carried out by bottom blowing argon gas; The bottom-blown argon flow rate is 100~200 NL / min.

4. The method for adding aluminum in the LF refining of high-alumina steel according to claim 1, characterized in that, The soft-blowing treatment includes soft-blowing argon gas treatment; The flow rate of the soft-blown argon gas is 30~50 NL / min; The duration of soft blowing treatment is ≥5 minutes.

5. The method for adding aluminum in the LF refining of high-alumina steel according to claim 1, characterized in that, The slag-forming agent includes lime and pre-melted slag; The amount of lime added is 4~7 kg / t of molten steel; The amount of pre-melted slag added is 0.5~2 kg / t of molten steel; The sum of FeO and MnO content in the refining slag is ≤1.0%.

6. The method for adding aluminum in the LF refining of high-alumina steel according to claim 1, characterized in that, The temperature of the molten steel in the converter is 1580~1620℃; The temperature of the molten steel during the refining process is 1590~1630℃; The refining time is ≥32 minutes.

7. The method for adding aluminum in the LF refining of high-alumina steel according to claim 1, characterized in that, The target range for controlling the aluminum content in the molten steel is 3.0~4.5%; The temperature of the molten steel being tapped is 1610~1630℃.

8. A high-aluminum steel, characterized in that, It is prepared by the LF refining aluminum addition method for high-aluminum steel as described in any one of claims 1 to 7.

9. The high-aluminum steel according to claim 8, characterized in that, The aluminum content in the high-alumina steel is 3.0~4.5%; The sulfur content in the high-aluminum steel is ≤0.003%; The aluminum yield in the high-aluminum steel is ≥90%.

10. The application of the high-alumina steel according to any one of claims 8 to 9, characterized in that, The high-alumina steel is used in the preparation of high-alumina TRIP steel, high-alumina electrical steel, high-alumina mold steel, high-alumina steel sheet for automobiles, or high-alumina steel sheet for engineering machinery.

Images