A high-aluminum steel and a method of smelting the same

Abstract

This application discloses a high-alumina steel and its smelting method, solving the technical problem of high total oxygen content in high-alumina steel in the prior art. The high-alumina steel smelting method of this application is applicable to high-alumina steel with an Al mass fraction ≥ 1.5%. The smelting method includes: Step 1, adding aluminum for deoxidation during the converter tapping process to obtain deoxidized molten steel; Step 2, adding silicon-manganese alloy during the LF refining process of the deoxidized molten steel to bring the silicon-manganese content in the molten steel to the target range, obtaining alloyed molten steel; Step 3, adjusting the Al2O3 mass fraction in the slag on the surface of the alloyed molten steel to 40%–50% before the end of LF refining to adsorb inclusions; Step 4, subjecting the LF-refined molten steel to RH vacuum treatment, adding aluminum during the RH vacuum treatment process to bring the aluminum content to the target range. The high-alumina steel obtained by the smelting method of this application has a total oxygen (TO) content of 6-8 ppm, which is low; the area ratio of Al2O3 inclusions is 0.0009-0.0011%, which is low; the aluminum element recovery rate is 41-45%; and the loss is low.

Description

Technical Field

[0001] This application belongs to the field of high-alumina steel smelting technology, specifically relating to a high-alumina steel and its smelting method. Background Technology

[0002] In the composition design of high-strength steel, aluminum plays a role in stabilizing austenite, resulting in a residual austenite structure. During deformation, the residual austenite transforms into martensite, which improves the strength and toughness of the strip steel.

[0003] For high-alumina steel, where the aluminum content reaches more than 1%, the smelting process generally involves first adding silicon-manganese alloying and then adding aluminum alloy for aluminum alloying. However, this treatment method leaves many inclusions in the steel, resulting in a high total oxygen content in the final product. Summary of the Invention

[0004] To address the technical problem of high total oxygen content in high-aluminum steel, this application provides a high-aluminum steel and its smelting method. In a first aspect of this application, a method for smelting high-alumina steel is provided, the smelting method comprising the following steps: Step 1: Aluminum is added during the converter tapping process to deoxidize the steel and obtain deoxidized molten steel; Step 2: Add silicon-manganese alloy during the LF refining process of deoxidized molten steel to bring the silicon-manganese content in the molten steel to the target range and obtain alloyed molten steel. Step 3: Before the LF refining is completed, adjust the mass fraction of Al2O3 in the slag on the surface of the alloyed steel liquid to 40%~50% to adsorb inclusions. Step 4: Perform RH vacuum treatment on the LF refined molten steel. Add aluminum during the RH vacuum treatment process to bring the aluminum content to the target range and complete the smelting of high-aluminum steel with an Al mass fraction ≥1.5%.

[0005] In some embodiments, in step 3, the slag on the surface of the adjusted alloyed steel melt contains 40% to 50% CaO and 5% to 8% MgO by mass.

[0006] In some embodiments, in step 3, the ratio of the mass fraction of CaO to the mass fraction of Al2O3 in the slag on the surface of the adjusted alloyed steel melt is 1.2-1.8, and the ratio of the sum of the mass fractions of CaO and MgO to the mass fraction of Al2O3 is 1.25-1.9.

[0007] In some embodiments, in step 3, the slag on the surface of the alloyed steel melt is adjusted 3-5 minutes before the end of LF refining.

[0008] In some embodiments, in step 1, aluminum is added during the converter tapping process to deoxidize the molten steel until the mass fraction of aluminum in the molten steel is ≤0.05%.

[0009] In some embodiments, in step 1, the mass fraction of aluminum added to the molten steel during the converter tapping process is 0.03-0.05%.

[0010] In some embodiments, prior to LF refining, the deoxidized molten steel is bottom-blown with a stirring gas at a flow rate of 10-40 NL / min for 2-6 minutes to promote the flotation of inclusions.

[0011] In some embodiments, the capacity of the converter, the refining furnace used for LF refining, and the refining furnace used for RH vacuum treatment are all 150-300t.

[0012] In a second aspect of this application, a high-alumina steel is provided, which is obtained by smelting using the high-alumina steel smelting method of the first aspect.

[0013] In some embodiments, the high-aluminum steel contains: Al mass fraction of 1.5%~2.0%, Si mass fraction of ≥1.5%, and Mn mass fraction of ≥2.0%.

[0014] The high-alumina steel smelting method provided in the embodiments of this application is applicable to high-alumina steel with an Al mass fraction ≥ 1.5%. The smelting method includes the following steps: Step 1, adding aluminum for deoxidation during the converter tapping process to obtain deoxidized molten steel; Step 2, adding silicon-manganese alloy during the LF refining process of the deoxidized molten steel to make the silicon-manganese content in the molten steel reach the target range to obtain alloyed molten steel; Step 3, adjusting the mass fraction of Al2O3 in the slag on the surface of the alloyed molten steel to 40%~50% before the end of LF refining to adsorb inclusions; Step 4, subjecting the LF-refined molten steel to RH vacuum treatment, adding aluminum during the RH vacuum treatment process to make the aluminum content reach the target range to complete the smelting of high-alumina steel.

[0015] This application involves adding aluminum in two stages. The first addition occurs during the converter tapping stage, where aluminum primarily removes dissolved oxygen from the molten steel. At this stage, most inclusions are clustered, easily floating alumina inclusions, with a smaller portion being blocky, non-floating alumina inclusions. Before LF refining, most of the clustered alumina inclusions float and are removed. The remaining blocky, non-floating alumina inclusions, along with the silicon-manganese alloy added during LF refining, form a composite liquid inclusion (DS) containing Si, Mn, Al, and O. Before the end of LF refining, the slag composition is adjusted to enhance its adsorption capacity for the composite liquid inclusion (DS), thus allowing it to float and be removed. A second addition of aluminum occurs during the RH vacuum treatment. Due to the vacuum conditions and extremely low dissolved oxygen in the molten steel, the added aluminum is primarily used for alloying, with minimal formation of alumina inclusions and no liquid inclusion (DS) formation. This improves aluminum yield and stabilizes the alloying operation.

[0016] Therefore, in the smelting process of high-alumina steel, this application adjusts the slag to remove endogenous liquid inclusions (DS) as much as possible, and performs aluminum alloying in the RH vacuum stage. This avoids the formation of foreign inclusions, ensures the aluminum yield, and stabilizes the alloying operation. The high-alumina steel obtained by the smelting method provided in this application has a total oxygen (TO) content of 6-8 ppm, which is low; the area ratio of Al2O3 inclusions is 0.0009-0.0011%, which is low; the aluminum element yield is 41-45%, and the loss is low. Attached Figure Description

[0017] Figure 1 A process flow diagram of a high-alumina steel smelting method according to one or more embodiments of this application is shown. Detailed Implementation

[0018] To enable those skilled in the art to more clearly understand this application, the technical solutions in the embodiments of this application 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 this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0019] The first aspect of this application provides a method for smelting high-alumina steel. The smelted high-alumina steel has a low total oxygen content, a small inclusion area ratio, a high aluminum yield, and a low cost.

[0020] Please combine Figure 1 The smelting method for high-alumina steel provided in this application includes the following steps: Step 1: Aluminum is added during the converter tapping process to deoxidize the steel and obtain deoxidized molten steel.

[0021] After the converter smelting is completed, aluminum is added to the molten steel during the tapping process. The aluminum can be aluminum granules or aluminum-iron. The purpose of adding aluminum at this stage is to remove dissolved oxygen in the molten steel to a lower level. Since the dissolved oxygen content in the molten steel is high at tapping, reaching 350-450 ppm, most of the products resulting from the reaction between the added Al and the oxygen in the molten steel exist as clusters of alumina inclusions, which are easily floated to the slag for removal; a small portion of the products remain in the molten steel as small pieces of alumina.

[0022] In some embodiments, during step 1, aluminum is added during the converter tapping process to deoxidize the molten steel until the mass fraction of aluminum in the molten steel is ≤0.05%. Controlling the aluminum content in the deoxidized molten steel to ≤0.05% results in a dissolved oxygen content of 5-10 ppm, which is equivalent to removing dissolved oxygen from the molten steel to a very low level. The oxygen in the molten steel will then be converted into metal oxides and adsorbed by the slag, thereby reducing the total oxygen content in the product.

[0023] If the aluminum content in the deoxidized molten steel is too low, the deoxidized molten steel will still contain a high level of dissolved oxygen. In the subsequent LF refining process, the Al in the molten steel will be gradually oxidized to aluminum oxide, and the aluminum oxide will remain in the molten steel in a small, non-floating state. This will not only reduce the Al yield, but also increase the amount of inclusions that need to be removed from the molten steel in the subsequent process.

[0024] In some embodiments, in step 1, the mass fraction of aluminum added to the molten steel during the converter tapping process is 0.03-0.05%. If the aluminum content in the deoxidized molten steel is too low, the dissolved oxygen content in the molten steel may be high. In the subsequent silicon-manganese alloying process, the dissolved oxygen will consume some of the silicon-manganese, affecting the yield of silicon-manganese.

[0025] Soft blowing is used to promote the flotation of inclusions in the deoxidized molten steel. Specifically, in some embodiments, before LF refining, the deoxidized molten steel is bottom-blown with a stirring gas at a flow rate of 10-40 NL / min for 2-6 minutes to promote the flotation of inclusions. This is referred to as soft blowing by those skilled in the art, meaning bottom blowing with a relatively low flow rate. This can promote the flotation of clustered and small-sized alumina inclusions in the molten steel to the slag for removal, reducing the amount of composite liquid inclusions (DS) formed after silicon-manganese alloying, and also preventing secondary oxidation caused by exposed molten steel.

[0026] Step 2: During the LF refining process of deoxidized molten steel, silicon-manganese alloy is added to bring the silicon-manganese content in the molten steel to the target range, thereby obtaining alloyed molten steel.

[0027] During the LF refining process, most of the clustered alumina and some small alumina particles have floated to the slag for removal. At this point, the oxygen content in the molten steel is low. Adding ferrosilicon alloy at this stage not only achieves the alloying of ferrosilicon and manganese, ensuring that the molten steel meets the product composition target, but also guarantees the yield of ferrosilicon and manganese. In some embodiments, the ferrosilicon alloy is added within 3-8 minutes after the start of LF refining.

[0028] The silicon-manganese alloy can be made of ferromanganese or ferrosilicon, or it can be a silicon-manganese alloy containing both manganese and silicon. This application does not impose specific restrictions on the choice of alloy.

[0029] Step 3: Before the LF refining is completed, adjust the Al2O3 content in the slag on the surface of the alloyed steel liquid to 40%~50% to adsorb inclusions.

[0030] Because a silicon-manganese alloy is added during the LF refining process, in addition to alloying the molten steel with silicon and manganese, the silicon, manganese, and a small amount of alumina in small lumps, along with oxygen in the molten steel, form composite liquid inclusions (DS). These composite liquid inclusions appear as small droplets in the molten steel. These small droplet-like composite liquid inclusions have good wettability with the molten steel, are easily entrained within it, and are difficult to float to the slag. Adjusting the alumina content in the slag to 40%–50% can improve the wettability between the slag and the composite liquid inclusions, increase the efficiency of liquid inclusions entering the slag at the steel-slag interface, and thus fully adsorb the liquid inclusions, reducing the total oxygen content of the molten steel. In some embodiments, the Al2O3 content is 40%–45%. In other embodiments, the Al2O3 content is 40%–43%.

[0031] In some embodiments, in step 3, the slag on the surface of the adjusted alloyed steel melt has a CaO mass fraction of 40%~50% and a MgO mass fraction of 5%~8%. That is, the composition of the slag on the surface of the adjusted alloyed steel melt is: CaO: 40%~50%; Al2O3: 40%~50%; MgO: 5%~8%, MnO+FeO≤1%, SiO2≤5%, and the remainder is unavoidable impurities.

[0032] In some embodiments, in step 3, the mass fraction ratio of CaO to Al2O3 in the slag on the surface of the adjusted alloyed molten steel is 1.2-1.8, and the sum of the mass fractions of CaO and MgO to the mass fraction of Al2O3 is 1.25-1.9. This type of slag not only readily adsorbs complex liquid inclusions (DS), but also has good fluidity, provides good coverage of the molten steel, and prevents secondary oxidation of the molten steel by air.

[0033] In step 3, 3-5 minutes before the end of LF refining, for example 4 minutes before the end of LF refining, the slag on the surface of the alloyed steel liquid is adjusted to allow time for the slag to adsorb liquid inclusions (DS).

[0034] Furthermore, before slag conditioning in LF refining, the slag composition on the surface of the alloyed steel melt is: CaO: 50%~55%; Al2O3: 30%~40%; MgO: 5%~8%, MnO+FeO≤1%, SiO2≤5%, with the remainder being unavoidable impurities. Before slag conditioning, a slag with a higher CaO content and a lower Al2O3 content is used. This is to ensure that the slag has a strong adsorption capacity for the small and aggregated Al2O3 inclusions produced by aluminum deoxidation. Even if the Al2O3 content in the slag increases as the Al2O3 inclusions float to the surface, the mass fraction of CaO to the mass fraction of Al2O3 in the slag remains at a suitable ratio, which is beneficial for absorbing the Al2O3 inclusions in the molten steel.

[0035] Step 4: Perform RH vacuum treatment on the LF refined molten steel. Add aluminum during the RH vacuum treatment process to bring the aluminum content to the target range and complete the smelting of high-aluminum steel with an Al mass fraction ≥1.5%.

[0036] Adding aluminum a second time during vacuum treatment to achieve alloying can improve aluminum yield and increase process stability. It eliminates the need for repeated aluminum additions to achieve the target alloy composition, simplifying the aluminum addition process. Furthermore, since aluminum is already added for deoxidation during converter tapping and for silicon-manganese alloying during LF refining, adding aluminum a second time during RH vacuum treatment is closer to continuous casting. The aluminum does not have sufficient time to react with dissolved oxygen in the molten steel to form excessive alumina inclusions, thus reducing the inclusion content in the high-alumina steel product. Moreover, the RH vacuum refining stage is a vacuum environment, where the risk of secondary oxidation of the molten steel is virtually eliminated, preventing the introduction of atmospheric oxygen into the molten steel and keeping the total oxygen content of the finished product within a low range.

[0037] In this application, the capacity of the converter, the refining furnace used in LF refining, and the refining furnace used in RH vacuum treatment are all 150-300t.

[0038] An embodiment of the second aspect of this application provides a high-alumina steel, which is obtained by smelting using the high-alumina steel smelting method of the first aspect.

[0039] In high-alumina steel: the mass fraction of Al is 1.5%~2.0%, the mass fraction of Si is ≥1.5%, and the mass fraction of Mn is ≥2.0%. Furthermore, high-alumina steel can be composed of the following components by mass fraction: Mn: 2.3%~2.7%, Al: 1.5%~2.0%, Si: 1.5%~1.9%, C: 0.1%~0.25%, S≤0.0020%; P≤0.010%, with the remainder being Fe and unavoidable impurities.

[0040] The following will further illustrate the high-alumina steel and its smelting method provided in this application with reference to specific embodiments.

[0041] Examples 1 to 5 Examples 1 to 5 provide a method for smelting high-alumina steel, wherein the target chemical composition of the high-alumina steel is shown in Table 1.

[0042] The smelting process for high-alumina steel is as follows: converter smelting, LF refining, and RH vacuum refining. The nominal capacity of the converter is 300t, and the specific steps are as follows: (1) Iron and scrap steel are added to the converter for smelting. After the converter smelting is completed, steel is tapped. During the tapping process, aluminum particles are added for deoxidation. The aluminum content in the molten steel after deoxidation is shown in Table 2.

[0043] (2) The ladle in step (1) is hoisted to the LF refining position. Argon gas is blown at the bottom when the LF enters the station. The molten steel is stirred with a weak gas volume. The stirring time and stirring flow rate are shown in Table 2. The main chemical components of the slag when the LF enters the station are shown in Table 3.

[0044] (3) The molten steel after step 2 is subjected to LF refining. Ferrosilicon and ferromanganese are added during the refining process to alloy the molten steel with silicon and manganese to the target chemical composition. 3-5 minutes before the end of LF refining, Al2O3 is added to the slag to adjust the composition of the slag. The composition after slag adjustment is shown in Table 3. The rest are impurities.

[0045] (4) The molten steel after the LF refining in step 3 is hoisted to the RH vacuum refining position for RH vacuum treatment. When the refining furnace reaches deep vacuum, aluminum particles are added into the vacuum chamber to adjust the aluminum composition to the target chemical composition.

[0046] (5) The molten steel after the RH vacuum treatment in step 4 is hoisted to the ladle slewing platform for casting.

[0047] Comparative Example 1 Comparative Example 1 provides a method for smelting high-aluminum steel, wherein the target chemical composition of the high-aluminum steel is the same as that in Example 1.

[0048] The smelting process for high-alumina steel is as follows: converter smelting, LF refining, and RH vacuum refining. The nominal capacity of the converter is 300t, and the specific steps are as follows: (1) Iron and scrap steel are added to the converter for smelting. After the converter smelting is completed, steel is tapped. During the tapping process, aluminum particles are added for deoxidation and alloying. The aluminum content in the molten steel after deoxidation and alloying is shown in Table 2.

[0049] (2) The ladle in step (1) is hoisted to the LF refining position. Argon gas is blown from the bottom when the LF enters the station. The molten steel is stirred with a weak gas volume. The stirring time and stirring flow rate are shown in Table 2. The main chemical components of the slag when the LF enters the station are shown in Table 3. The rest are impurities.

[0050] (3) The molten steel after step 2 is subjected to LF refining. Ferrosilicon and ferromanganese are added during the refining process to alloy the molten steel with silicon and manganese to the target chemical composition.

[0051] (4) The molten steel after the LF refining in step 3 is hoisted to the RH vacuum refining station for RH vacuum treatment.

[0052] (5) After the RH vacuum treatment in step 4, the molten steel is treated with calcium, then soft blown and hoisted to the ladle rotary platform for casting.

[0053] Comparative Example 2 Comparative Example 2 provides a method for smelting high-aluminum steel, wherein the target chemical composition of the high-aluminum steel is the same as that in Example 1.

[0054] The smelting process for high-alumina steel is as follows: converter smelting, LF refining, and RH vacuum refining. The nominal capacity of the converter is 300t, and the specific steps are as follows: (1) Iron and scrap steel are added to the converter for smelting. After the converter smelting is completed, steel is tapped. During the tapping process, aluminum iron is added for deoxidation. The aluminum content in the molten steel after deoxidation is shown in Table 2.

[0055] (2) The ladle in step (1) is hoisted to the LF refining position. Argon gas is blown from the bottom when the LF enters the station. The molten steel is stirred with a weak gas volume. The stirring time and stirring flow rate are shown in Table 2. The main chemical components of the slag when the LF enters the station are shown in Table 3. The rest are impurities.

[0056] (3) The molten steel after step 2 is subjected to LF refining. Ferrosilicon and ferromanganese are added during the refining process to alloy the molten steel with silicon and manganese to the target chemical composition.

[0057] (4) The molten steel after the LF refining in step 3 is hoisted to the RH vacuum refining station for RH vacuum treatment.

[0058] (5) Feed the molten steel after the RH vacuum treatment in step 4 to aluminum wire to achieve aluminum alloying to the target chemical composition, then perform calcium treatment, soft blowing, and then hoist the ladle rotary platform for casting.

[0059] Table 1

[0060] Table 2

[0061] Table 3

[0062] Table 4

[0063] In Table 4, the Al2O3 area ratio refers to the proportion of alumina inclusions in the unit area of ​​the sample observed, based on the inclusion statistics of the cast billets formed by casting the molten steel after the examples and comparative examples.

[0064] As can be seen from the data in Table 4, the smelting methods for high-aluminum steel provided in Examples 1 to 5 of this application result in a total oxygen (TO) content of 6-8 ppm in the billet, which is low. The area ratio of Al2O3 inclusions in the billet sample is 0.0009-0.0011%, which is low. The aluminum element recovery rate is 41-45%, which is low.

[0065] The high-alumina steel smelting method provided in Comparative Example 1, which involves first aluminum alloying in the converter and then refining and alloying silicon and manganese in the LF process, yields a billet with a total oxygen (TO) content of 13 ppm, which is higher than that in Examples 1 to 5 of this application. The area ratio of Al2O3 inclusions in the billet sample is 0.0021%, which is higher than that in Examples 1 to 5 of this application. The aluminum element recovery rate is 32%, and the aluminum loss is higher than that in Examples 1 to 5 of this application. The higher total oxygen content in Comparative Example 1 compared to Examples 1 to 5 of this application is due to the fact that after aluminum alloying, the oxygen content in the molten steel is low and the Al content is high. Al is very reactive and will continue to oxidize to form small blocky Al2O3 inclusions. After adding Si and Mn, the small blocky Al2O3 inclusions will form composite liquid DS inclusions, which are difficult to float and remove when they are trapped in the molten steel. Therefore, the total oxygen content in the final billet is high and the area ratio of Al2O3 inclusions is high. Furthermore, if aluminum is added too early, it will be lost in subsequent processes, which will also reduce the aluminum yield.

[0066] The high-alumina steel smelting method provided in Comparative Example 2, which involves first alloying silicon and manganese in the LF process and then feeding aluminum wire for aluminum alloying after the RH vacuum treatment, yielded a billet with a total oxygen (TO) content of 14 ppm, which is higher than that of Examples 1 to 5 of this application. The area ratio of Al2O3 inclusions in the billet sample was 0.0022%, which is also higher than that of Examples 1 to 5 of this application. The aluminum element recovery rate was 42%, which is comparable to that of Examples 1 to 5 of this application. The higher total oxygen content in Comparative Example 2 compared to Examples 1 to 5 of this application is due to the fact that aluminum is very reactive during aluminum alloying after the RH vacuum treatment, which may cause the molten steel to churn. This can lead to a chemical reaction between oxygen in the air and aluminum to form foreign Al2O3. The foreign Al2O3 can form a composite liquid DS inclusion with silicon and manganese in the molten steel, which is difficult to float and remains in the molten steel. In addition, since the aluminum wire is added close to the continuous casting time, even if the foreign Al2O3 does not form liquid DS inclusions, the time is too short to allow it to float and be removed. Both conditions combined result in a high area ratio of Al2O3 inclusions, leading to a high total oxygen content in the final cast billet. Since the timing of aluminum alloying is close to that of continuous casting, aluminum loss is low, and the aluminum yield is comparable to that of Examples 1 to 5 of this application.

[0067] In the high-alumina steel and its smelting method provided in this application, aluminum is added in two stages. The first addition of aluminum occurs during the converter tapping stage. At this stage, the main function of aluminum is to remove dissolved oxygen from the molten steel. Most of the inclusions formed during this stage are clustered, easily floating alumina inclusions, while a small portion are blocky, difficult-to-float alumina inclusions. Before LF refining, most of the clustered alumina inclusions float to the surface and are removed. The small portion of blocky, difficult-to-float alumina inclusions, together with the silicon-manganese alloy added during the LF refining stage, form a composite liquid inclusion DS containing Si, Mn, Al, and O. Before the end of LF refining, the composition of the slag is adjusted to improve the slag's ability to adsorb the composite liquid inclusion DS, thereby causing the generated liquid inclusion DS to float to the surface and be removed. Then, aluminum is added a second time during the RH vacuum treatment. Due to the vacuum conditions and the extremely low dissolved oxygen in the molten steel, the added aluminum is mainly used for alloying, and it does not form alumina inclusions or liquid inclusions (DS). This improves the aluminum yield and stabilizes the alloying operation.

[0068] This application employs a converter + LF + RH process to produce silicon-manganese alloy steel with an Al content greater than 1.5%, with aluminum deoxidation at the converter endpoint. In the early stage of LF refining, high-CaO slag is used to absorb Al2O3 inclusions, followed by Si-Mn alloying. Simultaneously, the composition of the LF refining slag is altered to absorb liquid inclusions (DS) containing Si, Mn, Al, and O. Al alloying is adjusted once during the RH vacuum treatment stage, eliminating the need for Ca treatment and soft blowing after the RH vacuum treatment. This produces high-aluminum silicon-manganese alloy steel with a total oxygen content below 0.0008% and an Al2O3 inclusion area ratio below 0.0011%.

[0069] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0070] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0071] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0072] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0073] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for smelting high-alumina steel, characterized in that, The smelting method includes the following steps: Step 1: During the converter tapping process, aluminum is added to deoxidize the molten steel until the mass fraction of aluminum in the molten steel is 0.03%~0.05%, thus obtaining deoxidized molten steel; Step 2: Add silicon-manganese alloy during the LF refining process of deoxidized molten steel to bring the silicon-manganese content in the molten steel to the target range and obtain alloyed molten steel. Step 3: Before the LF refining is completed, adjust the mass fraction of Al2O3 in the slag on the surface of the alloyed steel liquid to 40.2%~50%, the mass fraction of CaO to 40%~50%, and the mass fraction of MgO to 5%~8% to adsorb inclusions. Step 4: Perform RH vacuum treatment on the LF refined molten steel. During the RH vacuum treatment, aluminum is added to adjust the Al alloy once so that the aluminum content reaches the target range, thus completing the smelting of high-aluminum steel with an Al mass fraction of 1.5%~2.0%.

2. The method for smelting high-alumina steel according to claim 1, characterized in that, In step 3, 3-5 minutes before the end of LF refining, the slag on the surface of the alloyed steel liquid is adjusted.

3. The method for smelting high-alumina steel according to claim 1, characterized in that, Before LF refining, the deoxidized molten steel is bottom-blown with a stirring gas at a flow rate of 10-40 NL / min for 2-6 minutes to promote the flotation of inclusions.

4. The method for smelting high-alumina steel according to claim 1, characterized in that, The capacity of the converter, the refining furnace used for LF refining, and the refining furnace used for RH vacuum treatment are all 150-300t.

5. A high-aluminum steel, characterized in that, Obtained by smelting high-aluminum steel using the smelting method described in any one of claims 1-4; The high-alumina steel contains 6ppm to 8ppm of total oxygen and 0.0009% to 0.0011% of Al2O3 inclusions.

6. The high-aluminum steel according to claim 5, characterized in that, In the high-alumina steel: the mass fraction of Al is 1.5%~2.0%, the mass fraction of Si is ≥1.5%, and the mass fraction of Mn is ≥2.0%.

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