Method for producing ultra-low carbon steel containing titanium and aluminum

Abstract

The invention provides a method for producing ultra-low carbon steel containing titanium and aluminum. The method comprises a converter process, an RH process and a continuous casting process which are carried out in sequence, in the converter process, an inclusion modifier coating is firstly formed on the surface of a steel ladle wall before tapping, and then a passivated lime powder layer is formed on the surface of the steel ladle wall; and after tapping, adding a high-aluminum slag modifier into the molten steel, and then blowing large argon from the bottom of a steel ladle for stirring. According to the method provided by the invention, the titanium-aluminum-containing ultra-low carbon steel can be produced in a short process, the number of inclusions such as Al2O3 in the casting blank is reduced, and the steel cleanliness of the titanium-aluminum-containing ultra-low carbon steel is improved.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting and refining, and in particular to a method for producing titanium-aluminum-containing ultra-low carbon steel. Background Art

[0002] As my country's energy conservation and emission reduction efforts continue to deepen, more and more steelmaking companies are exploring the elimination of the LF process to achieve economical and efficient production of steel grades; especially for ultra-low carbon steels such as automotive plates. In order to reduce the long logistics time and the oxygen transfer between steel and slag caused by the LF treatment process, more and more manufacturers are adopting the "converter-RH-continuous casting" short process production.

[0003] However, for high-quality ultra-low carbon steels such as automotive panels, since the carbon content of the converter steel is controlled at a low level, the oxygen activity in the steel and the oxidizing property of the converter final slag are relatively high, in order to maintain sufficient free oxygen in the steel for decarburization during the RH treatment process, aluminum-containing slag regulators are generally added to the ladle after the steel is tapped. In order to ensure that there is sufficient free oxygen in the steel, blowing of argon for slag reaction is also prohibited at the end of steel tapping, resulting in poor melting of the slag and uneven composition. After RH deoxidation and alloying, the modification effect on inclusions such as Al2O3 in the steel is weakened, making it difficult to achieve stable production of ultra-low carbon steels such as high-cleanliness automotive panels.

[0004] Therefore, in order to solve the above problems in the production of high-quality ultra-low carbon steel such as automotive plates using the short process of "converter-RH-continuous casting", steelmaking companies often add lime, fluorite and other auxiliary materials in the converter steel-making process, and then add aluminum-containing slag regulators to the ladle surface to deoxidize the ladle slag after steel-making. However, since auxiliary materials such as lime have a high melting point and a density much lower than the density of molten steel, a large amount of unmelted auxiliary materials still float on the ladle surface at the end of steel-making, and the ability of the ladle slag to absorb inclusions is reduced. In view of the above problems, the researchers adjusted the ladle slag modifiers in the short process, for example:

[0005] The Chinese patent with publication number CN107815519A discloses a ladle slag modifier and a modification treatment method, wherein the modifier comprises: CaO 50-80%, SiO2 5-15%, MgO5-20%, Al2O3 5-15%, S≤0.08%, P≤0.025%; the modifier is used to modify the ladle slag by adding the modifier during the steelmaking and tapping process; the modifier can modify the high melting point phase of the ladle slag into low melting point slag to reduce the precipitation of the high melting point phase of the ladle slag, thereby reducing its melting temperature and adhesion performance, overcoming the phenomenon of ladle slag sticking and weight increase when producing high silicon and high aluminum steel, and ensuring smooth production.

[0006] The patent with the publication number CN117488184A discloses a method for using a converter direct silicon-killed steel ladle slag modifier, which includes adding 2.0-5.0 kg / t of lime, 0-1.0 kg / t of fluorite and 0-1.0 kg / t of quartz sand at the beginning of steel tapping; adding 1.5 kg / t-3 kg / t of pre-melted ladle slag and 0-1.0 kg / t of ferrosilicon at the end of steel tapping; strong blowing of argon gas at the bottom of the ladle for slag making; after the strong blowing, medium-intensity argon blowing for 2-5 minutes; after the medium-intensity argon blowing, calcium treatment can be carried out according to the process requirements of the steel grade; after the calcium treatment, soft argon blowing is used to even out the composition and temperature and remove inclusions. This method realizes efficient desulfurization under the process conditions of direct silicon-killed steel converter, and ensures the castability of molten steel under the condition of low oxidizability of molten steel.

[0007] The above two patents add lime, fluorite or ladle slag modifier to modify the ladle slag or inclusions in the steel during or at the beginning of the steel tapping process, which can wash the molten steel to a certain extent, especially in the later stage, combined with the LF process, heating and strong stirring, which can better achieve the slag-metal reaction and achieve the effect of modifying the inclusions in the steel. However, for ultra-low carbon steel that is directly subjected to RH without LF, it is difficult to achieve complete melting of the added solid slag and sufficient slag-metal reaction by only relying on the slag-metal reaction of 4 to 6 minutes of steel tapping.

[0008] The Chinese patent with the publication number CN118600149A discloses a slag washing and direct production process for small-section aluminum-containing square billets. The method controls the temperature of the molten steel at the end of the converter at 1670-1680°C; adds fluorine-free slag washing material, high calcium ash, medium carbon ferromanganese, aluminum blocks, etc. to the molten steel for slag washing and alloying; blows large argon gas to melt the top slag during the steel-making process and at the end of steel-making for 3-5 minutes, and then feeds the calcium wire and then blows argon softly for 12-15 minutes; wherein, the amount of fluorine-free slag washing material is 1kg / t steel, and the amount of high calcium ash is 4kg / t steel. Compared with the normal process without slag washing, the time of blowing argon is extended in this method, and the smelting cycle of the slag washing and direct production process is also significantly shortened compared with the traditional refining smelting cycle.

[0009] The above patent adopts the process of "strong stirring + weak stirring" after steelmaking, which achieves better modification of inclusions in steel than the traditional slag washing process. However, the strong stirring after the furnace and long-term argon blowing cause great loss of molten steel temperature and free oxygen in the steel, which is not suitable for the production of pre-deoxidized steel such as ultra-low carbon.

[0010] Therefore, for the short-process converter process-RH process-continuous casting process of titanium-containing ultra-low carbon steel, it is of great significance to modify the residual Al2O3 inclusions in the steel in order to obtain molten steel with higher cleanliness. Summary of the invention

[0011] The technical problem solved by the present invention is to provide a method for producing titanium-aluminum-containing ultra-low carbon steel. The method provided in the present application can stably control inclusions in the steel and ensure the cleanliness of the steel.

[0012] In view of this, the present application provides a method for producing titanium-aluminum-containing ultra-low carbon steel, comprising: a converter process-RH process-continuous casting process performed in sequence;

[0013] In the converter process, before steel is tapped, an inclusion modifier coating is first formed on the ladle wall surface and then a passivating lime powder layer is formed; after steel is tapped, a high-aluminum slag regulator is added to the molten steel, and then large argon is blown from the ladle bottom for stirring.

[0014] Preferably, the inclusion modifier of the inclusion modifier coating comprises, by mass percentage, the following: CaO: 64-74%, Al2O3: 15.5-19.5%, SiO2: 0-4.5%, TiO2: 3-6%, Re: 0.5%-0.9%.

[0015] Preferably, the inclusion modifier is a premelt obtained by melting lime, corundum slag and rutile and then grinding them into powder.

[0016] Preferably, the thickness of the inclusion modifier coating is 2 to 5 mm, and the thickness of the passivating lime powder layer is 2 to 5 mm.

[0017] Preferably, after adding the high-aluminum slag adjusting agent, the ladle slag TFe≤5%, and the Ca / Al ratio is 2.5-2.8.

[0018] Preferably, the argon blowing flow rate of the ladle bottom blowing large argon stirring is 350-500 NL / min, and the argon blowing time is 0.5-1.5 min.

[0019] Preferably, in the RH process, a small amount of argon is blown from the bottom of the ladle before adding aluminum for deoxidation and alloying, and the argon blowing flow rate is 140-180 NL / min; and the argon blowing flow rate is reduced to 80-130 NL / min before adding titanium alloy.

[0020] Preferably, in the continuous casting process, after the ladle starts pouring, the argon blowing flow rate at the bottom of the ladle is 70-110NL / min, when the ladle is poured 1 / 4-1 / 3, the argon blowing flow rate at the bottom of the ladle is adjusted to 50-90NL / min, and when the ladle is poured 2 / 3-3 / 4, the bottom argon blowing is stopped.

[0021] Preferably, the inclusion modifier comprises: CaO: 65-72%, Al2O3: 16-18%, SiO2: 0.5-4.0%, TiO2: 3.2-5.0%, Re: 0.6%-0.8%.

[0022] Preferably, the components of the titanium-aluminum ultra-low carbon steel, measured in mass percentage, include: C≤0.0035%, Si≤0.020%, Mn 0.11-0.16%, P≤0.010%, S≤0.012%, Al0.03-0.06%, Ti 0.05-0.07%, and the balance is Fe.

[0023] The present application provides a method for producing titanium-aluminum-containing ultra-low carbon steel, which comprises a converter process-RH process-continuous casting process performed in sequence, wherein in the converter process, before steel is tapped, an inclusion modifier coating is first formed on the surface of the ladle wall and then a passivation lime powder layer is formed, after steel is tapped, a high-aluminum slag regulating agent is added to the molten steel, and then a large amount of argon is blown from the bottom of the ladle for stirring; in the converter process, the present application sprays an inclusion modifier onto the inner wall of the ladle, and sprays the passivation lime powder on the outside of the modifier, blows a large amount of argon from the bottom of the ladle during and after the converter steel tapping, the molten steel is flushed with the ladle wall, the passivation lime powder on the outer layer reacts strongly with the molten steel with slag-gold to generate liquid slag, and compared with the solid lime auxiliary material originally added, a rapid and stable modification of the ladle slag for converter steel tapping is achieved; in the RH decarburization process In the process, due to the circulation of molten steel in the vacuum chamber and the ladle, the passivating lime on the ladle wall is further dissolved in the steel. After adding aluminum for deoxidation, the deoxidation product Al2O3 in the steel reacts with the CaO dissolved in the steel and the inclusion modifier on the ladle wall to generate low-melting-point calcium-aluminum inclusions. The ladle begins to blow argon from the bottom to further improve the kinetic conditions of the slag-metal reaction and promote the floating and removal of inclusions. The ladle continuous casting process further modifies Al2O3 and other inclusions in the steel while promoting the floating of inclusions. In the later stage of ladle casting, the Al2O3 in the steel has been basically modified, and argon blowing is stopped to prevent the ladle slag from being drawn into the tundish. Furthermore, the inclusion modifier is added with an appropriate amount of TiO2, which can effectively reduce the burning loss of Ti element in the steel and stabilize the accuracy of molten steel composition.

[0024] The method for producing titanium-aluminum ultra-low carbon steel provided in the present application effectively avoids the problems of difficulty in modifying inclusions in steel and low steel cleanliness caused by conventional short-process production; the method provided in the present application effectively realizes the improvement of the cleanliness of titanium-aluminum ultra-low carbon steel under the short process, and the number of Al2O3 inclusions larger than 3μm in the ingot is reduced by more than 50%, and the number of TiO2-Al2O3 inclusions is reduced by more than 65%. The improvement of steel cleanliness ensures the stability of the formulation of high-end products such as automotive plates, and has significant economic and social benefits. DETAILED DESCRIPTION

[0025] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0026] In view of the limited effect of modifying inclusions such as Al2O3 in the short-process production of ultra-low carbon steel in the prior art, and the difficulty in achieving the problem of high-cleanliness ultra-low carbon steel production, the embodiment of the present invention discloses a method for producing ultra-low carbon steel containing titanium and aluminum, which sprays an inclusion modifier on the inner wall surface of the ladle and sprays passivating lime powder on the surface of the inclusion modifier in the converter process to facilitate the full reaction of the non-metallic oxides of the steel grade with the inclusion modifier on the inner wall of the ladle, thereby achieving effective modification of the Al2O3 inclusions in the steel, and the subsequent continuous casting process can promote the floating removal of inclusions in the steel, and further modify the residual Al2O3 inclusions in the steel to obtain molten steel with higher cleanliness. Specifically, the present application provides a method for producing ultra-low carbon steel containing titanium and aluminum, comprising: a converter process-RH process-continuous casting process performed in sequence;

[0027] In the converter process, before steel is tapped, an inclusion modifier coating is first formed on the ladle wall surface and then a passivating lime powder layer is formed; after steel is tapped, a high-aluminum slag regulator is added to the molten steel, and then large argon is blown from the ladle bottom for stirring.

[0028] In the short-process method for producing titanium-aluminum ultra-low carbon steel provided in the present application, it includes a converter process-RH process-continuous casting process performed in sequence; no other processes are performed between the above three processes, and except for the improvements of the following schemes, other technical means of the above three processes are not adjusted, and are still performed in a manner familiar to technical personnel in this field.

[0029] The composition of the titanium-aluminum ultra-low carbon steel described in the present application is calculated by mass percentage, including: C≤0.0035%, Si≤0.020%, Mn 0.11-0.16%, P≤0.010%, S≤0.012%, Al0.03-0.06%, Ti 0.05-0.07%, and the balance is Fe; specifically, the C content is 0.0010-0.0035%, the Si content is 0.010-0.020%, the Mn content is 0.11-0.16%, the P content is 0.005-0.009%, the S content is 0.004-0.012%, the Al content is 0.03-0.06%, and the Ti content is 0.05-0.07 %, and the balance is Fe; more specifically, the C content is 0.0025-0.0029%, the Si content is 0.016-0.018%, the Mn content is 0.12-0.15%, the P content is 0.006-0.009%, the S content is 0.008-0.010%, the Al content is 0.04-0.05%, the Ti content is 0.05-0.06%, and the balance is Fe.

[0030] In the converter process, the present application first forms an inclusion modifier coating on the surface of the ladle wall before steel is tapped and then forms a passivating lime powder layer; the above-mentioned inclusion modifier coating and passivating lime powder layer can be formed in a manner well known to those skilled in the art. For example, they can be formed on the surface of the ladle wall by spraying. The inclusion modifier of the inclusion modifier coating includes, by mass percentage, CaO: 64-74%, Al2O3: 15.5-19.5%, SiO2: 0-4.5%, TiO2: 3-6%, Re: 0.5%-0.9%, and the rest are inevitable impurities; specifically, the inclusion modifier includes: CaO: 65-72%, Al2O3: 16-18%, SiO2: 0.5-4.0%, TiO2: 3.2-5.0%, Re: 0.6%-0.8%, and the rest are inevitable impurities; for example, the content of CaO in this application is 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%; the content of Al2O3 is 15.5%, 16. 0%, 16.5%, 17.0%, 17.5%, 18.0%, 18.5%, 19.0%, 19.5%; SiO2 content is 0.5%, 0.8%, 1.0%, 1.3%, 1.5%, 1.7%, 2.0%, 2.2%, 2.5%, 2.6%, 2.8%, 3.0%, 3.2%, 3.4%, 3.5%, 3.8 %, 4.0%; TiO2 content is 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%; Re content is 0.5%, 0.6%, 0.7%, 0.8%, 0.9%. The inclusion modifier is a pre-melted material, which is obtained by melting lime, corundum slag and rutile according to the composition ratio and then grinding.

[0031] In the present application, the thickness of the inclusion modifier coating is 2 to 5 mm, and the thickness of the passivating lime powder layer is 2 to 5 mm; more specifically, the thickness of the inclusion modifier coating is 2 mm, 3 mm, 4 mm or 5 mm, and the thickness of the passivating lime powder layer is 2 mm, 3 mm, 4 mm or 5 mm.

[0032] After steel is tapped, a high-aluminum slag-adjusting agent is added to the molten steel, and then a large amount of argon is blown at the bottom of the ladle for stirring; in this process, the high-aluminum slag-adjusting agent is a slag-adjusting agent well known to those skilled in the art, and this application does not impose any special restrictions on this, and the high-aluminum slag-adjusting agent is added to make the ladle slag TFe≤5%, and the Ca / Al ratio is 2.5-2.8. The argon blowing flow rate of the ladle bottom blowing large argon stirring is 350-500NL / min, and the argon blowing time is 0.5-1.5min; specifically, the argon blowing flow rate is 380-480NL / min, and the argon blowing time is 0.8-1.2min; more specifically, the argon blowing flow rate is 4000-430NL / min, and the argon blowing time is 0.9-1.1min.

[0033] In the converter process, during and after the converter steel tapping process, large amounts of argon are blown through the bottom of the ladle, the molten steel and the ladle wall are flushed, and the outer layer of passivated lime powder reacts strongly with the molten steel to produce liquid slag. This method achieves rapid and stable modification of the ladle slag during converter steel tapping; the TiO2 added to the inclusion modifier can effectively reduce the burnout of the Ti element in the steel and stabilize the accuracy of the molten steel composition.

[0034] After the converter process, the RH process begins. In the RH process, argon is blown from the bottom of the ladle. A small amount of argon is blown from the bottom of the ladle before the end of RH decarburization and the addition of aluminum deoxidation and alloying. The argon blowing flow rate is 140-180NL / min. Before adding titanium alloy, the argon blowing flow rate is reduced to 80-130NL / min, and the argon blowing is stopped until the end of the treatment. Specifically, the argon blowing flow rate is 140NL / min, 150NL / min, 160NL / min, 170NL / min, and 180NL / min, and the argon blowing flow rate is reduced to 80NL / min, 90NL / min, 100NL / min, 110NL / min, 120NL / min, and 130NL / min. During the RH decarburization process, due to the circulation of molten steel in the vacuum chamber and the ladle, the passivating lime on the ladle wall is further dissolved in the steel; after aluminum deoxidation, the deoxidation product Al2O3 in the steel reacts with the CaO dissolved in the steel and the inclusion modifier on the ladle wall to generate low-melting-point calcium-aluminum inclusions. At this time, the ladle begins to blow a small amount of argon from the bottom to further improve the kinetic conditions of the slag-metal reaction and promote the floating removal of inclusions.

[0035] After the RH process, the continuous casting process is carried out. In the continuous casting process, the argon blowing flow rate of the ladle bottom is 70-110NL / min after the ladle starts pouring. When the ladle pours 1 / 4-1 / 3, the argon blowing flow rate of the ladle bottom is adjusted to 50-90NL / min. When the ladle pours 2 / 3-3 / 4, the bottom argon blowing is stopped. Further, after the ladle starts pouring, the argon blowing flow rate of the ladle bottom is 80NL / min, 90NL / min, 100NL / min; the argon blowing flow rate of the ladle bottom is adjusted to 60NL / min, 70NL / min, 80NL / min. In the continuous casting process, the ladle continues to blow a small amount of argon at the bottom in the early and middle stages of ladle continuous casting, further modifying the inclusions such as Al2O3 in the steel while promoting the floating of the inclusions. In the late stage of ladle pouring, the Al2O3 in the steel has been basically modified, and the argon blowing is stopped to prevent the ladle slag from being drawn into the middle ladle.

[0036] The method for producing titanium-aluminum ultra-low carbon steel provided in the present application can improve the cleanliness of titanium-aluminum ultra-low carbon steel under a short process, so that the number of Al2O3 inclusions larger than 3μm in the ingot is reduced by more than 50%, and the number of TiO2-Al2O3 inclusions is reduced by more than 65%. The improvement of steel cleanliness ensures the stability of the formulation of high-end products such as automotive plates; the method provided in the present application can be promoted and applied to high-quality steels such as pipeline steel, SPHC, STB series, etc., and is also suitable for inclusion modification of long-process steel grades, which can achieve stable control of inclusions in steel and low-cost clean production of steel grades, and has significant economic and social benefits.

[0037] In order to further understand the present invention, the method for producing titanium-aluminum-containing ultra-low carbon steel provided by the present invention is described in detail below in conjunction with embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0038] Comparative Example 1

[0039] The molten steel smelting adopts the process flow of "converter process-RH process-continuous casting process", and the product composition is shown in Table 1:

[0040] Table 1 Main component requirements of steel grades / wt%

[0041] C Si Mn P S Al Ti 0.0029 0.018 0.12 0.009 0.008 0.045 0.06

[0042] Converter process: when 1 / 4 of the converter is tapped, active lime and fluorite are added into the ladle, with the added amount being 3.5kg / t steel and 1.0kg / t steel respectively; after tapping, high-aluminum slag regulator is added to the surface of the ladle, with the added amount being 2.5kg / ton steel; argon blowing after the furnace: after tapping, the molten steel is subjected to strong argon blowing and stirring for 3 minutes, with an argon blowing flow rate of 300NL / min; then weak argon blowing and stirring for 5 minutes, with an argon blowing flow rate of 150NL / min;

[0043] RH process: no argon blowing from the bottom of the ladle;

[0044] Continuous casting process: No argon blowing from the bottom of the ladle.

[0045] Comparative Example 2

[0046] The molten steel smelting adopts the process flow of "converter process-RH process-continuous casting process", and the product composition is shown in Table 2:

[0047] Table 2 Main component requirements of steel grades / wt%

[0048] C Si Mn P S Al Ti 0.0025 0.012 0.15 0.009 0.010 0.04 0.05

[0049] Converter process: Before tapping, the ladle wall is sprayed with a 3mm thick inclusion modifier, the composition by mass percentage is: CaO: 65%, Al2O3: 19.5%, SiO2: 0.5%, TiO2: 4.5%, Re: 0.9%, and the rest are unavoidable impurities;

[0050] After the steel is tapped, high aluminum slag regulator is added to the steel to make the ladle slag TFe≤5%, and the Ca / Al ratio is 2.5-2.8. After the addition is completed, the ladle bottom is blown with large argon for stirring, the blowing flow rate is 350NL / min, and the blowing time is 1.0min;

[0051] RH process: After RH decarburization, start blowing small amounts of argon from the bottom of the ladle before adding aluminum deoxidation alloying, with an argon blowing flow rate of 140NL / min; before adding titanium alloy, reduce the flow rate to 110NL / min, and stop blowing argon after the treatment;

[0052] Continuous casting process: After the ladle starts pouring, the argon blowing flow rate at the bottom of the ladle is 110NL / min, and the molten steel is softly blown with argon. When the ladle is poured with 1 / 4 of the molten steel, the bottom blowing flow rate of the ladle is adjusted to 80NL / min. When the ladle pouring amount is 2 / 3, turn off the bottom argon blowing.

[0053] Example 1

[0054] The molten steel smelting adopts the process flow of "converter process-RH process-continuous casting process", and the product composition is shown in Table 3:

[0055] Table 3 Main component requirements of steel grades / wt%

[0056] C Si Mn P S Al Ti 0.0025 0.016 0.16 0.010 0.012 0.03 0.05

[0057] Converter process: Before tapping, the ladle wall is first sprayed with a 3mm thick inclusion modifier, the composition by mass percentage is: CaO: 65%, Al2O3: 19.5%, SiO2: 0.5%, TiO2: 4.5%, Re: 0.9%, and the rest are inevitable impurities; then a 4mm thick passivation lime powder layer is sprayed;

[0058] After the steel is tapped, high aluminum slag regulator is added to the steel to make the ladle slag TFe≤5%, and the Ca / Al ratio is 2.5-2.8. After the addition is completed, the ladle bottom is blown with large argon for stirring, the blowing flow rate is 350NL / min, and the blowing time is 1.5min;

[0059] RH process: After RH decarburization, start blowing small amounts of argon from the bottom of the ladle before adding aluminum deoxidation alloying, with an argon blowing flow rate of 140NL / min; before adding titanium alloy, reduce the flow rate to 110NL / min, and stop blowing argon after the treatment;

[0060] Continuous casting process: After the ladle starts pouring, the argon blowing flow rate at the bottom of the ladle is 110NL / min, and the molten steel is softly blown with argon. When the ladle is poured with 1 / 4 of the molten steel, the bottom blowing flow rate of the ladle is adjusted to 80NL / min. When the ladle pouring amount is 2 / 3, turn off the bottom argon blowing.

[0061] Example 2

[0062] The molten steel smelting adopts the process flow of "converter process-RH process-continuous casting process", and the product composition is shown in Table 4:

[0063] Table 4 Main component requirements of steel grades / wt%

[0064] C Si Mn P S Al Ti 0.0026 0.015 0.11 0.006 0.010 0.06 0.07

[0065] Converter process: Before tapping, the ladle wall is first sprayed with a 5mm thick inclusion modifier, the composition by mass percentage is: CaO: 70%, Al2O3: 15.5%, SiO2: 2.2%, TiO2: 3.2%, Re: 0.5%, and the rest are inevitable impurities; then spray a 2mm thick passivation lime powder layer;

[0066] After the steel is tapped, high aluminum slag regulator is added to the steel to make the ladle slag TFe≤5%, and the Ca / Al ratio is 2.5-2.8. After the addition is completed, the ladle bottom is blown with large argon for stirring, the blowing flow rate is 500NL / min, and the blowing time is 0.6min;

[0067] RH process: After RH decarburization, start blowing small amounts of argon from the bottom of the ladle before adding aluminum deoxidation alloying, with an argon blowing flow rate of 180NL / min; before adding titanium alloy, reduce the flow rate to 90NL / min, and stop blowing argon after the treatment;

[0068] Continuous casting process: After the ladle starts pouring, the argon blowing flow rate at the bottom of the ladle is 70NL / min, and the molten steel is softly blown with argon. When the ladle is poured with 1 / 3 of the molten steel, the bottom blowing flow rate of the ladle is adjusted to 50NL / min. When the ladle pouring amount is 3 / 4, turn off the bottom argon blowing.

[0069] The effects of the methods provided in the embodiments and comparative examples on the cleanliness of steel are shown in the following table:

[0070] Table 5 The total number of inclusions larger than 3 μm in the ingot before and after implementation (inclusive / mm 2 )

[0071] Group <![CDATA[Al2O3]]> <![CDATA[TiO2-Al2O3]]> <![CDATA[(Total number of (Al2O3 + TiO2 - Al2O3) inclusions)]]> Comparative Example 1 4.6 4.0 8.6 Comparative Example 2 4.4 3.6 8.0 Example 1 2.2 1.1 3.3 Example 2 1.8 1.3 3.1

[0072] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0073] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for producing titanium-aluminum-containing ultra-low carbon steel, comprising: Converter process - RH process - continuous casting process are carried out in sequence; In the converter process, before steel is tapped, an inclusion modifier coating is first formed on the ladle wall surface and then a passivating lime powder layer is formed; after steel is tapped, a high-aluminum slag regulator is added to the molten steel, and then large argon is blown from the ladle bottom for stirring.

2. The method according to claim 1, characterized in that: The inclusion modifier of the inclusion modifier coating comprises, by mass percentage, 64-74% of CaO, 15.5-19.5% of Al2O3, 0-4.5% of SiO2, 3-6% of TiO2, and 0.5%-0.9% of Re.

3. The method according to claim 2, characterized in that The inclusion modifier is a premelt material obtained by melting lime, corundum slag and rutile and then grinding them into powder.

4. The method according to claim 1, characterized in that The thickness of the inclusion modifier coating is 2 to 5 mm, and the thickness of the passivation lime powder layer is 2 to 5 mm.

5. The method according to claim 1, characterized in that After the high-aluminum slag adjusting agent is added, the ladle slag TFe≤5%, and the Ca / Al ratio is 2.5-2.

8.

6. The method according to claim 1, characterized in that The argon blowing flow rate of the ladle bottom blowing large argon stirring is 350-500 NL / min, and the argon blowing time is 0.5-1.5 min.

7. The method according to claim 1, characterized in that In the RH process, a small amount of argon is blown from the bottom of the ladle before adding aluminum for deoxidation and alloying, and the blowing argon flow rate is 140-180 NL / min; and the blowing argon flow rate is reduced to 80-130 NL / min before adding titanium alloy.

8. The method according to claim 1, characterized in that In the continuous casting process, after the ladle starts pouring, the argon blowing flow rate of the ladle bottom is 70-110NL / min. When the ladle is poured 1 / 4-1 / 3, the argon blowing flow rate of the ladle bottom is adjusted to 50-90NL / min. When the ladle is poured 2 / 3-3 / 4, the bottom argon blowing is stopped.

9. The method according to claim 2, characterized in that: The inclusion modifier comprises: CaO: 65-72%, Al2O3: 16-18%, SiO2: 0.5-4.0%, TiO2: 3.2-5.0%, Re: 0.6%-0.8%.

10. The method according to any one of claims 1 to 9, characterized in that: The components of the titanium-aluminum-containing ultra-low carbon steel, measured in percentage by mass, include: C≤0.0035%, Si≤0.020%, Mn 0.11-0.16%, P≤0.010%, S≤0.012%, Al 0.03-0.06%, Ti0.05-0.07%, and the balance is Fe.