A kind of high aluminum steel and its preparation method and product

Abstract

The present application provides a high-aluminum steel and a preparation method and product thereof, wherein the preparation method of the high-aluminum steel comprises the following steps: S10 adding aluminum to the converter molten steel for the first time to carry out deoxidation and desulfurization treatment to obtain deoxidized and desulfurized molten steel; S20 adding alloy materials and LF refining slag to the deoxidized and desulfurized molten steel to carry out refining treatment to obtain high-aluminum steel molten steel, that is, high-aluminum steel; wherein the addition of alloy materials includes the second addition of aluminum, and the second addition of aluminum specifically includes: adding aluminum blocks in 3 to 5 times, stirring with 500 to 800NL / min argon gas for 0.5 to 2 minutes after each addition, and then sending electricity to melt the aluminum blocks through the LF furnace electrodes. The preparation method can be used to obtain high-aluminum steel containing 3wt% to 5wt% of aluminum, and the aluminum recovery rate is high during the preparation process, and the aluminum composition in the high-aluminum steel can be effectively and stably controlled to obtain high-aluminum steel with high quality and high pass rate.

Description

Technical Field

[0001] The present application relates to the field of iron and steel metallurgy, and in particular to a high-aluminum steel and a preparation method and product thereof. Background Art

[0002] The current main promotion direction of high-aluminum steel is to replace container plates to achieve low-density weight reduction, corrosion resistance and paint-free. In addition, this steel can be used as a low-density prototype steel, on which a series of low-density steels such as high-strength, wear-resistant, high-strength weather-resistant, and bullet-proof steels for mixing barrels can be developed, which has a certain market prospect.

[0003] Since the Al content in lightweight corrosion-resistant steel is much higher than that in conventional steel grades, the interaction between high-aluminum molten steel and slag during the smelting process far exceeds the impact produced during the smelting of conventional steel grades. The aluminum recovery rate during the smelting process is very low, resulting in a low pass rate for the prepared high-aluminum steel, affecting production efficiency.

[0004] Therefore, it is necessary to provide a method for preparing high-aluminum steel with a higher aluminum yield. Summary of the invention

[0005] The present application provides a high-aluminum steel and a preparation method and product thereof. The preparation method can be used to obtain high-aluminum steel containing 3wt% to 5wt% aluminum, and the aluminum yield rate is high during the preparation process, and the aluminum content in the high-aluminum steel can be accurately controlled.

[0006] In a first aspect, the present application provides a method for preparing high-aluminum steel, comprising the following steps:

[0007] S10: adding aluminum to the converter molten steel for the first time to perform deoxidation and desulfurization treatment to obtain deoxidized and desulfurized molten steel;

[0008] S20: adding alloy materials and LF refining slag to the deoxidized and desulfurized molten steel for refining to obtain high-aluminum steel molten steel, i.e., high-aluminum steel;

[0009] The adding of alloy material includes adding aluminum for the second time, and the second adding of aluminum specifically includes: adding aluminum block in 3 to 5 times, stirring with 500 to 800 NL / min argon gas for 0.5 to 2 minutes after each addition, and then sending electricity through the LF furnace electrode to melt the aluminum block.

[0010] In the technical solution of the present application, aluminum is added to the molten steel twice. The first addition of aluminum is to remove oxygen and sulfur in the molten steel, and the second addition of aluminum is to alloy the molten steel so that the aluminum content in the molten steel meets the requirements of high-aluminum steel. In particular, the second addition of aluminum is further divided into 3 to 5 additions. On the one hand, the N content in the molten steel can be reduced, and on the other hand, the aluminum recovery rate can be increased. Therefore, the high-aluminum steel obtained using the method of the present application has an easy-to-control aluminum content and low inclusions, thereby improving the production efficiency and quality of the high-aluminum steel.

[0011] In some embodiments of the present application, in step S10, the mass percentage of aluminum in the deoxidized and desulfurized molten steel is 0.08% to 0.15%.

[0012] In some embodiments of the present application, in step S20, adding the alloy material specifically includes:

[0013] First add manganese; then when the sulfur content in the molten steel is ≤0.003wt% and the temperature is 1565-1570℃, add aluminum for the second time; finally add ferrosilicon.

[0014] In some embodiments of the present application, in step S20, the addition amount of the LF refined slag is 5-10 kg / ton of steel.

[0015] In some embodiments of the present application, in step S20, the LF refined slag includes, by mass percentage, 30% to 50% of hot refined slag of low carbon and low silicon steel, 10% to 20% of low silicon refined pre-melted slag and 30% to 50% of lime;

[0016] The hot refined slag of the low-carbon and low-silicon steel is composed of the following components by mass percentage: CaO: 52% to 58%, Al2O3: 26% to 36%, MgO: 5% to 10%, SiO2: 0 to 5%, and the balance is unavoidable impurities; wherein w(CaO) / w(Al2O3)=1.0 to 1.5;

[0017] The low-silicon refined pre-molten slag is composed of the following components in mass percentage: CaO: 45% to 55%, Al2O3: 34% to 46%, MgO: 0 to 6%, SiO2: 0 to 5%, Fe2O3: 0 to 1.5%, and the remainder is inevitable impurities.

[0018] In some embodiments of the present application, in the step S20, in the refining process, the final refining slag is composed of the following components in mass percentage: CaO: 50%~55%, Al2O3: 45%~50%, MgO: 5%~10%, SiO2: 0~1%, TFe: 0~0.5%, MnO: 0~0.5%, which are unavoidable impurities; wherein w(CaO) / w(Al2O3)=0.8~1.2.

[0019] In some embodiments of the present application, in step S20, the total oxygen content in the high-aluminum steel molten steel is ≤0.0005%, and the nitrogen content is ≤0.0020%, calculated by mass percentage.

[0020] In some embodiments of the present application, the aluminum content in the high-aluminum steel accounts for more than 90% of the total mass of the aluminum added in the first aluminum addition and the second aluminum addition.

[0021] In a second aspect, the present application provides a high aluminum steel, which is prepared according to the preparation method described in any embodiment of the first aspect;

[0022] Wherein, the high aluminum steel is composed of the following components by mass percentage:

[0023] C: 0~0.06%;

[0024] Si: 0.15%~0.25%;

[0025] Mn: 0.5%~0.8%;

[0026] Al: 3.5% to 5%;

[0027] P: 0~0.02%;

[0028] S: 0~0.006%.

[0029] In the technical solution of the present application, the high-aluminum steel prepared by the preparation method of the embodiment in the first aspect has a high and stable aluminum content, with few oxide and sulfide inclusions.

[0030] In a third aspect, the present application provides a high-aluminum steel product, which is obtained by processing the high-aluminum steel obtained according to the preparation method described in any embodiment of the first aspect or the high-aluminum steel described in any embodiment of the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0032] Figure 1 This is a flow chart of the technical solution of the first aspect of this application.

[0033] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0034] The various embodiments or implementation schemes in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments.

[0035] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the implementation or examples are included in at least one implementation or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same implementation or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more implementations or examples in a suitable manner.

[0036] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0037] The inventors found that high-aluminum steel has a high aluminum content, but due to the active nature of aluminum, it is not only easy to react with silicon dioxide in the slag to increase the silicon content in the molten steel, but also causes changes in the properties of the slag. On the other hand, the aluminum in the molten steel is prone to secondary oxidation, which leads to a decrease in the closeness of the steel and causes the quality of the high-aluminum steel to be poor.

[0038] There is no report in the prior art about the preparation method of high aluminum steel, especially the preparation method of high aluminum steel with an aluminum content of 3wt% to 5wt%. Since the aluminum in the high aluminum steel reacts with various components and oxygen in the slag during the smelting process, the aluminum yield in the high aluminum steel is very low, so that the composition of the prepared high aluminum steel fluctuates greatly, and thus the production qualification rate of the obtained high aluminum steel is low.

[0039] In this regard, the inventors provide a method for preparing high-aluminum steel, which can effectively improve the yield of aluminum preparation, while controlling the content of oxygen and nitrogen in the high-aluminum steel, thereby reducing inclusions in the high-aluminum steel and improving the quality of the high-aluminum steel.

[0040] First, as Figure 1 As shown, the present application provides a method for preparing high aluminum steel, comprising the following steps:

[0041] S10: adding aluminum to the converter molten steel for the first time to perform deoxidation and desulfurization treatment to obtain deoxidized and desulfurized molten steel;

[0042] S20: adding alloy materials and LF refining slag to the deoxidized and desulfurized molten steel for refining to obtain high-aluminum steel molten steel, i.e., high-aluminum steel;

[0043] Among them, adding alloy materials includes adding aluminum for the second time, and the second adding aluminum specifically includes: adding aluminum blocks in 3 to 5 times, stirring with 500 to 800NL / min argon gas for 0.5 to 2 minutes after each addition, and then sending electricity through the LF furnace electrode to melt the aluminum block.

[0044] In the technical solution of the present application, aluminum is added to the molten steel twice. The first addition of aluminum is to remove oxygen and sulfur in the molten steel, and the second addition of aluminum is to alloy the molten steel so that the aluminum content in the molten steel meets the requirements of high-aluminum steel. In particular, the second addition of aluminum is further divided into 3 to 5 additions. On the one hand, the N content in the molten steel can be reduced, and on the other hand, the aluminum recovery rate can be increased. Therefore, the high-aluminum steel obtained using the method of the present application has an easy-to-control aluminum content and low inclusions.

[0045] In the technical solution of the present application, in step S10, the main purpose of adding aluminum for the first time is desulfurization and deoxidation. The amount of aluminum added for the first time is relatively small, which can make the generated oxide inclusions smaller in size and less in number, making them more easily adsorbed by LF refining slag during the refining process, thereby reducing the inclusions in high-aluminum steel.

[0046] In step S20, the purpose of adding aluminum for the second time is to make the aluminum content in the molten steel meet the requirements of high-aluminum steel. The amount of aluminum added for the second time is relatively large. Adding aluminum twice can reduce the consumption of aluminum deoxidation and desulfurization, thereby improving the aluminum recovery rate. In addition, the generated inclusions are also easier to remove, thereby improving the quality of high-aluminum steel. At the same time, LF refining slag is added. The purpose of LF refining slag is to add it to the molten steel. After melting, it can cover the surface of the molten steel to prevent oxygen in the air from oxidizing the aluminum in the molten steel. In addition, the refining slag has the function of absorbing oxides and nitrides in the molten steel, thereby reducing the oxygen and nitrogen content in the molten steel, reducing the inclusions in the molten steel, and improving the quality of the high-aluminum steel molten steel.

[0047] It should be noted that in the technical solution of the present application, the second aluminum addition method is to add aluminum blocks to the molten steel in 3 to 5 times, stir with 500 to 800 NL / min argon for 0.5 to 2 minutes after each addition, and then send electricity to melt the aluminum blocks through the LF furnace electrode. For those skilled in the art, since the amount of aluminum added during the second aluminum alloying is large, in order to prevent excessive aluminum addition in a single time, which leads to aluminum oxidation or reaction with some components in the refined slag, resulting in a decrease in the aluminum yield, the general aluminum addition method is to add aluminum blocks as many times as possible. The inventors found that by reducing the number of additions during the second aluminum addition, adding aluminum blocks in a concentrated manner, and reducing the flow rate of argon and the stirring intensity compared to the prior art, using the LF furnace electrode to send a point to melt the aluminum blocks, the concentration of aluminum content in a certain area of ​​the molten steel can be increased, the secondary oxidation of aluminum can be reduced, and the precipitation rate of inclusions can be accelerated. At the same time, the inclusions are refined and easily absorbed by the refined slag and removed, the inclusion content in the molten steel is reduced, and the aluminum yield is increased. Furthermore, aluminum blocks are added to the molten steel in 3 to 4 times, and stirred with 500 to 800 NL / min argon for 1 to 2 minutes after each addition. The aluminum blocks are then melted by sending electricity through the LF furnace electrodes. The high-aluminum steel obtained has lower total oxygen and nitrogen contents and a higher aluminum yield.

[0048] It should be noted that the purpose of the second addition of aluminum is for alloying, so the amount of addition is determined according to the aluminum content in the high-aluminum steel to be prepared, and those skilled in the art can determine the amount of addition according to actual needs. In this technical solution, aluminum blocks are added to the molten steel in 3 to 5 times. Generally speaking, the aluminum blocks to be added are roughly divided into 3 to 5 portions for addition. It can be understood that the mass difference of each portion of aluminum block does not exceed 20% of the arithmetic mean of the total mass of the second addition of aluminum.

[0049] It should be noted that the technical solution of the present application does not further limit the converter steel. It can be understood by those skilled in the art that since the final slag of converter steelmaking is oxidizing slag, it will reduce the aluminum recovery rate. Therefore, it is necessary to reduce the amount of converter slag as much as possible, and to adjust the slag after the converter steelmaking is completed to reduce the oxidizing property of the final slag. As an example, after the converter steelmaking is completed, it is necessary to add 2-3 kg / ton of molten steel lime and 3-4 kg / ton of molten steel aluminum blocks for slag adjustment, and use slag stopper + slide plate to double slag stopper to reduce the amount of slag, and control the slag thickness ≤80 mm, that is, the slag amount ≤3 kg / ton of molten steel, so as to obtain converter steel with lower oxidizing property, thereby improving the aluminum recovery rate.

[0050] In some embodiments of the present application, the current delivered by the LF furnace electrode is 50000-55000 A. By using a relatively large current to melt the aluminum block, the aluminum content in a certain area of ​​the molten steel can be quickly increased, thereby increasing the aluminum recovery rate.

[0051] In some embodiments of the present application, in step S10, the mass percentage of aluminum in the deoxidized and desulfurized molten steel is 0.08% to 0.15%.

[0052] In some of the above embodiments, the first addition of aluminum needs to control the mass percentage of aluminum in the molten steel to 0.08% to 0.15%. If the aluminum content is too high, the inclusion size will become larger and it will not be easily absorbed by the refining slag, affecting the aluminum yield; if the aluminum content is too low, it will lead to insufficient deoxidation in the early stage, resulting in a large number of inclusions in the subsequent alloying process, which will also reduce the aluminum yield. Therefore, the mass percentage of aluminum in the molten steel needs to be controlled at 0.08% to 0.15% through the first addition of aluminum. Furthermore, when the mass percentage of aluminum in the deoxidized and desulfurized molten steel is 0.08% to 0.1%, there are fewer inclusions in the high-aluminum steel and a higher aluminum yield.

[0053] In some embodiments of the present application, the particle size of the aluminum block is 20-50 mm, and the aluminum content is ≥99%.

[0054] In some embodiments of the present application, in step S20, adding the alloy material specifically includes:

[0055] First add manganese; then when the sulfur content in the molten steel is ≤0.003wt% and the temperature is 1565-1575℃, add aluminum for the second time; finally add ferrosilicon.

[0056] In some of the above embodiments, since the alloy components of high-aluminum steel are generally not only aluminum, but also may contain manganese and silicon, among which manganese has a certain deoxidation and desulfurization ability, adding it before the second addition of aluminum can improve the aluminum recovery rate and reduce the inclusions in the molten steel. In addition, since the aluminum in the molten steel can reduce the silicon dioxide in the refined slag, thereby increasing the silicon content in the molten steel, when alloying the high-aluminum steel, ferrosilicon needs to be added at the end to prevent the silicon content in the high-aluminum steel from exceeding the standard and affecting the quality of the high-aluminum steel. At the same time, when the sulfur content in the molten steel is ≤0.003wt% and the temperature is 1565-1575℃, adding aluminum for the second time can further reduce the high-temperature oxidation loss of aluminum, thereby improving the aluminum recovery rate.

[0057] In some embodiments of the present application, in step S20, the addition amount of LF refined slag is 5-10 kg / ton of steel.

[0058] In some of the above embodiments, the addition amount of LF refining slag is controlled at 5-10 kg / ton of steel. This is because LF refining slag is a reducing slag. On the one hand, it can isolate the air and prevent the molten steel from absorbing gas. Through the slag layer covering, it can effectively prevent the aluminum in the molten steel from being oxidized by oxygen and the nitrogen from entering the molten steel through ionization, thereby effectively reducing inclusions and improving the aluminum recovery rate. On the other hand, it can effectively capture inclusions in the molten steel and purify the molten steel. During the LF refining process, argon bottom blowing can be used to make the inclusions in the molten steel gather and float and be absorbed by the refining slag. However, the refining slag will inevitably contain silicon dioxide. Too much addition will cause the silicon content in the high-aluminum steel to exceed the standard, and the aluminum recovery rate will be reduced. Therefore, it needs to be controlled. The addition amount of LF refining slag is 5-10 kg / ton of steel.

[0059] In some embodiments of the present application, during the refining process, 500-800 NL / min of bottom-blown argon gas is used for stirring.

[0060] In some embodiments of the present application, in the refining process, the refining temperature is controlled to be 1575-1590°C through electrode submerged arc heating, wherein in the electrode submerged arc heating, the arc is started with a current of 30,000-35,000A each time power is supplied, and the current is switched to 50,000-55,000A after 0.5-2 minutes.

[0061] In some embodiments of the present application, in step S20, the LF refined slag includes, by mass percentage, 30% to 50% of hot refined slag of low carbon and low silicon steel, 10% to 20% of low silicon refined pre-melted slag and 30% to 50% of lime;

[0062] The hot refined slag of low carbon and low silicon steel is composed of the following components by mass percentage: CaO: 52% to 58%, Al2O3: 26% to 36%, MgO: 5% to 10%, SiO2: 0 to 5%, and the balance is unavoidable impurities; wherein w(CaO) / w(Al2O3)=1.0 to 1.5;

[0063] The low silicon refined pre-molten slag is composed of the following components in mass percentage: CaO: 45% to 55%, Al2O3: 34% to 46%, MgO: 0 to 6%, SiO2: 0 to 5%, Fe2O3: 0 to 1.5%, and the balance is inevitable impurities.

[0064] In some of the above embodiments, the LF refining slag includes 30% to 50% of hot refining slag of low carbon and low silicon steel, 10% to 20% of low silicon refining pre-melted slag and 30% to 50% of lime in terms of mass percentage. This is because the hot refining slag of low carbon and low silicon steel is a reducing slag, and the silicon dioxide content is low and the aluminum oxide content is high, so it can be reused. In addition, the hot refining slag of low carbon and low silicon steel generally has a temperature higher than 1000°C, which can quickly cover the surface of molten steel, thereby reducing the oxidation of molten steel by air. At the same time, the basicity, aluminum oxide content and fluidity of the LF refining slag are adjusted by adding low silicon refining pre-melted slag and lime, so as to obtain LF refining slag with high basicity, low oxidation and good fluidity. High basicity is conducive to desulfurization, low oxidation is conducive to deoxidation, and good fluidity is conducive to slag reaction, thereby reducing the content of inclusions in high aluminum steel and improving the aluminum recovery rate.

[0065] In some embodiments of the present application, in step S20, during the refining process, the final refining slag is composed of the following components in mass percentage: CaO: 50%~55%, Al2O3: 45%~50%, MgO: 5%~10%, SiO2: 0~1%, TFe: 0~0.5%, MnO: 0~0.5%, which are unavoidable impurities; wherein w(CaO) / w(Al2O3)=0.8~1.2.

[0066] In some of the above embodiments, by using the above LF refining slag, it is possible to control the final refining slag to be composed of the above components after LF refining treatment. The final refining slag has good fluidity, can prevent slag crusting in the ladle, and can also reduce the reaction between aluminum in the molten steel and FeO and silicon dioxide in the slag, thereby reducing the oxidation of aluminum during the refining process and improving the aluminum recovery rate.

[0067] It should be noted that TFe refers to the total iron content known to those skilled in the art.

[0068] In some embodiments of the present application, in step S20, in the high-aluminum steel molten steel, the total oxygen content is ≤0.0005%, and the nitrogen content is ≤0.0020%, measured in mass percentage.

[0069] In some of the above embodiments, high-aluminum steel melt is obtained by the preparation method of any embodiment of the first aspect of the present application. By detecting the total oxygen content in the melt, which is not more than 0.0005%, and the nitrogen content is not more than 0.0020%, measured by mass percentage, it is indicated that the high-aluminum steel melt has a very low inclusion content and a very high quality, which is beneficial to the further continuous casting of the steel melt and improves the production efficiency of the high-aluminum steel.

[0070] It should be noted that the total oxygen content refers to the weight of dissolved oxygen in molten steel and oxygen in oxidized inclusions. The total oxygen and nitrogen content in molten steel of high aluminum steel is measured by an oxygen-nitrogen combined analyzer.

[0071] In some embodiments of the present application, the aluminum content in the high-aluminum steel accounts for more than 90% of the total mass of the aluminum added in the first aluminum addition and the second aluminum addition.

[0072] In some of the above embodiments, high aluminum steel is obtained by the preparation method of any embodiment of the first aspect of the present application. After detection and calculation, the aluminum content in the high aluminum steel accounts for more than 90% of the total mass of aluminum added in the first aluminum addition and the second aluminum addition, that is, the aluminum recovery rate in the high aluminum steel prepared by this method is more than 90%. Therefore, the aluminum content in the high aluminum steel prepared by this method is stable, which can ensure the preparation of high-quality high aluminum steel.

[0073] More preferably, in some embodiments, the aluminum content in the high-aluminum steel accounts for more than 92% of the total weight of the aluminum added in the first aluminum addition and the second aluminum addition. That is, in some embodiments, the aluminum recovery rate is more than 92%.

[0074] In a second aspect, the present application provides a high aluminum steel, which is prepared according to the preparation method of any embodiment of the first aspect;

[0075] Among them, high aluminum steel is composed of the following components by mass percentage:

[0076] C: 0~0.06%;

[0077] Si: 0.15%~0.25%;

[0078] Mn: 0.5%~0.8%;

[0079] Al: 3.5% to 5%;

[0080] P: 0~0.02%;

[0081] S: 0~0.006%.

[0082] In the technical solution of the present application, the high aluminum steel prepared by the preparation method of the embodiment of the first aspect has a high and stable aluminum content, wherein oxide and sulfide inclusions are few. The aluminum content in the high aluminum steel can be as high as 3.5% to 5%. Since the higher the aluminum content in the steel, the lower the density, the high aluminum steel has a good application prospect.

[0083] In a third aspect, the present application provides a high-aluminum steel product, which is obtained by processing the high-aluminum steel obtained according to the preparation method of any embodiment of the first aspect or the high-aluminum steel according to any embodiment of the second aspect.

[0084] Hereinafter, the high aluminum steel and its preparation method and products of the present application are described in more detail through examples, but the present application is not limited to these examples at all.

[0085] The aluminum yield of high aluminum steel is calculated as follows:

[0086] Aluminum recovery rate = (total amount of high-aluminum steel liquid × aluminum content) / [(mass of aluminum block added for the first time + mass of aluminum block added for the second time) × aluminum content of aluminum block]

[0087] The aluminum block in the embodiment and the comparative example has an aluminum content of 99.2%.

[0088] Example 1

[0089] Preparation method of high aluminum steel smelted by Lian Steel:

[0090] After the converter is tapped, 720 kg of aluminum blocks are added to the molten steel, followed by 1.78 t of metallic manganese. When the sulfur content in the molten steel is 0.0028% and the temperature is 1572°C, 9.28 t of aluminum blocks are added in 5 equal portions. After each addition, 650 NL / min of argon gas is used to stir for 1 min, and then the aluminum blocks are melted by powering the LF furnace electrodes at 54,000 A. Then 1 t of lime and 1,500 kg of low-silicon refined pre-melted slag are added, and finally ferrosilicon is added according to the silicon content of the molten steel. After refining, 219.1 t of high-aluminum steel molten steel is obtained.

[0091] During the refining process, electrode submerged arc heating is used to ensure the refining temperature is 1565-1575°C. Each time the power is supplied for heating, the arc is started at 32000A, and then switched to 54000A for heating after 1 minute. The whole process is stirred with 720NL / min bottom blowing argon.

[0092] The total oxygen content in the high-aluminum steel molten steel was detected to be 0.0007%, the nitrogen content was 0.0019%, the aluminum content was 4.08%, and the aluminum recovery rate was 90.1%.

[0093] Example 2

[0094] Preparation method of high aluminum steel smelted by Lian Steel:

[0095] After the converter is tapped, 620kg of aluminum blocks are added to the molten steel, followed by 1.83t of metallic manganese. When the sulfur content in the molten steel is 0.0025% and the temperature is 1575℃, 9.25t of aluminum blocks are added in 4 equal portions. After each addition, 680NL / min of argon gas is used to stir for 1min, and then the aluminum blocks are melted through the LF furnace electrodes at 54000A. Then 1t of lime and 1500kg of low-silicon refined pre-melted slag are added, and finally ferrosilicon is added according to the silicon content of the molten steel. After refining, 217.2t of high-aluminum steel is obtained.

[0096] During the refining process, electrode submerged arc heating is used to ensure the refining temperature is 1565-1575°C. Each time the power is supplied for heating, the arc is started at 32000A, and then switched to 54000A for heating after 1 minute. The whole process is stirred with 730NL / min bottom blowing argon.

[0097] The total oxygen content in the high-aluminum steel molten steel was detected to be 0.0006%, the nitrogen content was 0.0017%, the aluminum content was 4.06%, and the aluminum recovery rate was 90.0%.

[0098] Example 3

[0099] Preparation method of high aluminum steel smelted by Lian Steel:

[0100] After the converter is tapped, 720kg of aluminum blocks are added to the molten steel, followed by 1.81t of metallic manganese. When the sulfur content in the molten steel is 0.0018% and the temperature is 1574°C, 9.09t of aluminum blocks are added in three equal portions, each time with 680NL / min argon stirring for 1min, and then the aluminum blocks are melted by powering the LF furnace electrodes at 54000A; then 1t of lime and 500kg of low-silicon refined pre-melted slag are added, and finally ferrosilicon is added according to the silicon content of the molten steel, and 218.2t of high-aluminum steel is obtained after refining.

[0101] During the refining process, electrode submerged arc heating is used to ensure the refining temperature is 1565-1575°C. Each time the power is supplied for heating, the arc is started at 32000A, and then switched to 54000A for heating after 1 minute. The whole process is stirred with 760NL / min bottom blowing argon.

[0102] The total oxygen content in the high-aluminum steel molten steel was detected to be 0.0005%, the nitrogen content was 0.0016%, the aluminum content was 4.1%, and the aluminum recovery rate was 91.8%.

[0103] Example 4

[0104] Preparation method of high aluminum steel smelted by Lian Steel:

[0105] After the converter is tapped, 600kg of aluminum blocks are added to the molten steel, followed by 1.82t of metallic manganese. When the sulfur content in the molten steel is ≤0.003% and the temperature is 1572°C, 9.06t of aluminum blocks are added in three equal portions. After each addition, the molten steel is stirred for 1min with 700NL / min argon gas, and then the aluminum blocks are melted by electricity through the LF furnace electrodes. Then 1t of lime, 500kg of low-silicon refined pre-melted slag, and 1t of hot refined slag of low-carbon and low-silicon steel are added. Finally, ferrosilicon is added according to the silicon content of the molten steel. After refining, 219.0t of high-aluminum steel molten steel is obtained.

[0106] During the refining process, electrode submerged arc heating is used to ensure that the refining temperature is 1565-1575°C. Each time the power is supplied for heating, the arc is started at 32000A, and then switched to 54000A for heating after 1 minute. The whole process is stirred with 740NL / min bottom blowing argon.

[0107] The total oxygen content in the high-aluminum steel molten steel was detected to be 0.0002%, the nitrogen content was 0.0012%, the aluminum content was 4.08%, and the aluminum recovery rate was 93.2%.

[0108] Comparative Example 1

[0109] Preparation method of high aluminum steel smelted by Lian Steel:

[0110] After the converter is tapped, 750kg of aluminum blocks are added to the molten steel, followed by 1.82t of metallic manganese. When the sulfur content in the molten steel is 0.004% and the temperature is 1595°C, 9.52t of aluminum blocks are added in 10 times on average, each time the aluminum blocks are melted for 3 minutes by stirring with 1200NL / min argon gas. 1t of lime and 1500kg of low-silicon refined pre-melted slag are also added. Finally, ferrosilicon is added according to the silicon content of the molten steel, and 218.2t of high-aluminum steel is obtained by refining.

[0111] During the refining process, electrode submerged arc heating is used to ensure that the refining temperature is above 1580°C. Each time the power is supplied for heating, the arc is started at 32000A, and then switched to 54000A for heating after 1 minute. During the whole process, 1300NL / min bottom blowing argon is used for large stirring.

[0112] The total oxygen content in the high-aluminum steel molten steel was detected to be 0.0008%, the nitrogen content was 0.0026%, the aluminum content was 4.05%, and the aluminum recovery rate was 86.7%.

[0113] It can be seen from the results of the above specific embodiments and comparative examples, where the comparative example is a method for preparing high-aluminum steel molten steel in the prior art, that the method for preparing high-aluminum steel provided in this application can effectively improve the aluminum yield during the refining process, and at the same time, the total oxygen and nitrogen content in the obtained high-aluminum steel is very low, indicating that the inclusion content is relatively low; in addition, during the refining process, the hot refining slag of low-carbon and low-silicon steel is used as LF refining slag, which can also effectively improve the aluminum yield. Therefore, the preparation method provided by this application can effectively and stably control the aluminum composition in high-aluminum steel, and obtain high-aluminum steel with high quality and high pass rate.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 application.

Claims

1. A method for preparing high aluminum steel, characterized in that: The following steps are involved: S10: adding aluminum to the converter molten steel for the first time to perform deoxidation and desulfurization treatment to obtain deoxidized and desulfurized molten steel; S20: adding alloy materials and LF refining slag to the deoxidized and desulfurized molten steel for refining to obtain high-aluminum steel molten steel, i.e., high-aluminum steel; Wherein, the added alloy material specifically includes: First add manganese; then when the sulfur content in the molten steel is ≤0.003wt% and the temperature is 1565-1575℃, add aluminum for the second time; finally add ferrosilicon; The second aluminum addition specifically includes: adding aluminum blocks in 3 to 5 times, stirring with 500 to 800 NL / min argon gas for 0.5 to 2 minutes after each addition, and then sending electricity through the LF furnace electrodes to melt the aluminum blocks.

2. The preparation method according to claim 1, characterized in that: In the step S10, the mass percentage of aluminum in the deoxidized and desulfurized molten steel is 0.08% to 0.15%.

3. The preparation method according to claim 1, characterized in that: In the step S20, the addition amount of the LF refined slag is 5-10 kg / ton of steel.

4. The preparation method according to claim 3, characterized in that: In the step S20, the LF refined slag comprises, by mass percentage, 30% to 50% of hot refined slag of low carbon and low silicon steel, 10% to 20% of low silicon refined pre-melted slag and 30% to 50% of lime; The hot refined slag of the low-carbon and low-silicon steel is composed of the following components by mass percentage: CaO: 52% to 58%, Al2O3: 26% to 36%, MgO: 5% to 10%, SiO2: 0 to 5%, and the balance is unavoidable impurities; wherein w(CaO) / w(Al2O3)=1.0 to 1.5; The low-silicon refined pre-molten slag is composed of the following components in mass percentage: CaO: 45% to 55%, Al2O3: 34% to 46%, MgO: 0 to 6%, SiO2: 0 to 5%, Fe2O3: 0 to 1.5%, and the remainder is inevitable impurities.

5. The preparation method according to claim 4, characterized in that: In the step S20, in the refining treatment, the final refining slag is composed of the following components in mass percentage: CaO: 50% to 55%, Al2O3: 45% to 50%, MgO: 5% to 10%, SiO2: 0 to 1%, TFe: 0 to 0.5%, MnO: 0 to 0.5%, which are unavoidable impurities; wherein w(CaO) / w(Al2O3)=0.8 to 1.

2.

6. The preparation method according to any one of claims 1 to 5, characterized in that: In the step S20, the total oxygen content in the high-aluminum steel melt is ≤0.0005%, and the nitrogen content is ≤0.0015%, by mass percentage.

7. The preparation method according to any one of claims 1 to 5, characterized in that: The aluminum content in the high-aluminum steel molten steel accounts for more than 90% of the total weight of the aluminum added in the first aluminum addition and the second aluminum addition.

8. A high aluminum steel, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 7; Wherein, the high aluminum steel is composed of the following components by mass percentage: C：0～0.06％； Si: 0.15%~0.25%; Mn: 0.5%~0.8%; Al：3.5％～5％； P：0～0.02％； S：0～0.006％。 9. A high aluminum steel product, characterized in that: The high aluminum steel obtained by the preparation method according to any one of claims 1 to 7 or the high aluminum steel according to claim 8 is processed to obtain a high aluminum steel product.

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