Preparation method of low-phosphorus low-sulfur high-manganese steel

Abstract

The application relates to the field of steel smelting, in particular to a preparation method of low-phosphorus low-sulfur high-manganese steel; the method comprises the following steps: carrying out desulfurization treatment on molten iron with a preset sulfur content to obtain desulfurized molten iron; carrying out dephosphorization treatment on the desulfurized molten iron with a first preset phosphorus content to obtain dephosphorized semi-steel; carrying out decarburization and dephosphorization smelting on the dephosphorized semi-steel with a second preset phosphorus content to obtain manganese-containing steel liquid; carrying out refining on the manganese-containing steel liquid, then carrying out vacuum degassing treatment, and then carrying out pouring to obtain low-phosphorus low-sulfur high-manganese steel billets; wherein, the first manganese raw material is added in the decarburization and dephosphorization smelting process, and the second manganese raw material is added in the refining process; the desulfurized molten iron is subjected to dephosphorization treatment, decarburization and dephosphorization treatment, desulfurization treatment and degassing treatment, the first manganese raw material and the second manganese raw material are added in the decarburization and dephosphorization smelting process and the desulfurization process respectively, the phosphorus content of the first manganese raw material and the second manganese raw material is limited, the sulfur content in the steel liquid is removed in the desulfurization process, and the low-phosphorus and low-sulfur content targets of the high-manganese steel are achieved.

Description

Technical Field

[0001] This application relates to the field of iron and steel smelting, and in particular to a method for preparing low-phosphorus, low-sulfur, and high-manganese steel. Background Technology

[0002] Manganese can significantly improve the hardenability, strength, and impact toughness of steel. High-manganese steel, with manganese as the main alloying element, has ultra-high strength and toughness, with a tensile strength of over 1000 MPa. Moreover, high-manganese steel has no low-temperature brittle transition temperature, and its elongation can still reach 75% even at -150℃. In addition, replacing expensive alloys such as Cr, Mo, Ni, and Nb with Mn has a more obvious price and production cost advantage, which can significantly reduce production costs. Therefore, medium and high manganese steels are widely used in wear-resistant steel, non-magnetic steel, automobile door pillars, and liquefied natural gas storage tanks.

[0003] High manganese steel is widely used in the die casting industry, but traditional production processes require heating furnaces such as electric arc furnaces for melting, resulting in high phosphorus content. Some high manganese steel products have a phosphorus content of 0.02%, and some even exceed 0.04%. Excessive phosphorus content limits the application of high manganese steel. High sulfur content causes "hot brittleness" in high manganese steel, also affecting its large-scale application.

[0004] Therefore, how to reduce the phosphorus and sulfur content of high-manganese steel is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] This application provides a method for preparing low-phosphorus, low-sulfur, high-manganese steel to solve the technical problem of excessive phosphorus and sulfur content in existing high-manganese steel.

[0006] In a first aspect, this application provides a method for preparing low-phosphorus, low-sulfur, high-manganese steel, the method comprising:

[0007] Molten iron is desulfurized to a preset sulfur content to obtain desulfurized molten iron;

[0008] The desulfurized molten iron is subjected to dephosphorization treatment with a first preset phosphorus content to obtain dephosphorized semi-steel;

[0009] The dephosphorized semi-steel is decarburized and dephosphorized with a second preset phosphorus content to obtain manganese-containing molten steel;

[0010] The manganese-containing molten steel is refined, then subjected to vacuum degassing, and then cast to obtain a low-phosphorus, low-sulfur, high-manganese steel billet.

[0011] In the decarburization and dephosphorization smelting process, a first manganese raw material is added, and in the refining process, a second manganese raw material is added.

[0012] The phosphorus content of the first manganese raw material is ≤0.015%, the phosphorus content of the second manganese raw material is ≤0.005%, and the phosphorus content of the desulfurized molten iron is ≤0.08%.

[0013] Optionally, the first manganese raw material needs to be preheated before being added, and the second manganese raw material needs to be preheated before being added.

[0014] The first preheating includes preheating by ladle baking or iron ladle baking, and the second preheating includes preheating by ladle baking or iron ladle baking.

[0015] Optionally, the final temperature of the first preheating is >800℃, and the final temperature of the second preheating is >800℃.

[0016] Optionally, the first manganese raw material includes at least one of manganese ore, high-carbon ferromanganese alloy, and medium-carbon ferromanganese alloy, and the second manganese raw material includes at least one of carbon ferromanganese alloy, low-carbon ferromanganese alloy, micro-carbon ferromanganese alloy, and metallic manganese.

[0017] Optionally, the amount of desulfurized molten iron fed into the dephosphorization treatment is 70% to 90% of the amount of molten steel before casting;

[0018] The first manganese raw material is added at a rate of 0.1 t / ton of molten steel to 0.25 t / ton of molten steel, and the second manganese raw material is added at a rate of...

[0019] = [(Target value of Mn element in the billet - Mn element content of the manganese-containing molten steel entering the station) × Total weight of manganese-containing molten steel + Target value of Mn element in the billet × Weight of the second manganese raw material)] / (Recovery rate of the second manganese raw material × Mn element content in the second manganese raw material) ± 0.01t / ton of molten steel.

[0020] Optionally, the first manganese raw material is added before the decarburization and dephosphorization smelting of the dephosphorized semi-steel, and the second manganese raw material is added when the manganese-containing molten steel is heated to 1500°C during the refining stage.

[0021] Optionally, the manganese content of the manganese-containing molten steel is 10% to 20%.

[0022] Optionally, the preset sulfur content is ≤0.002%, the first preset phosphorus content is ≤0.02%, and the second preset phosphorus content is ≤0.005%.

[0023] Optionally, the decarburization and dephosphorization smelting includes decarburization smelting and dephosphorization smelting. The dephosphorization smelting includes dephosphorization smelting by bottom blowing and stirring with a dephosphorizing agent after the decarburization smelting. The slag removal rate of the dephosphorization smelting is ≥90%.

[0024] Optionally, the vacuum degassing treatment time is 20 min to 30 min, and the minimum vacuum degree of the vacuum degassing treatment is <100 Pa.

[0025] The technical solutions provided in this application have the following advantages compared with the prior art:

[0026] This application provides a method for preparing low-phosphorus, low-sulfur, and high-manganese steel. The method involves treating desulfurized molten iron with dephosphorization, decarburization, dephosphorization, desulfurization, and degassing. A first manganese raw material and a second manganese raw material are added during the decarburization and dephosphorization smelting process and the desulfurization process, respectively. The phosphorus content of the first and second manganese raw materials is limited. By adding low-phosphorus manganese raw materials, not only is the sulfur content of the molten steel reduced during desulfurization, but the phosphorus content is also further reduced. This ensures that the phosphorus content in the billet is maintained at a lower level than in existing technologies, thus achieving the goal of low phosphorus and low sulfur content in high-manganese steel. Furthermore, it increases the manganese content of the refined manganese-containing molten steel, achieving alloying upstream, thereby reducing the pressure of subsequent alloying adjustments and avoiding the introduction of large amounts of phosphorus-containing impurities due to frequent subsequent alloying adjustments, further ensuring that the phosphorus content in the billet remains at a low level. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a flowchart illustrating the method provided in an embodiment of this application. Detailed Implementation

[0030] The present invention will be described in detail below with reference to specific embodiments and examples, thereby making the advantages and various effects of the present invention more clearly apparent. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the present invention.

[0031] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification shall prevail.

[0032] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0033] The inventive concept of this application is as follows: Existing companies producing high-manganese steel generally need to use electric arc furnaces to melt scrap steel, ferrochrome, and ferromanganese, and then cast the steel after the composition meets the requirements; or they need to equip themselves with heating furnaces to melt scrap steel, electrolytic manganese, and pig iron. If the amount of alloy added to high-manganese steel is large, current smelting processes require heating furnaces such as electric arc furnaces to melt the alloy, which limits the production of high-manganese steel.

[0034] The technical solution provided by the embodiments of the present invention is to solve the above-mentioned technical problems, and the general idea is as follows:

[0035] In one embodiment of this application, such as Figure 1 As shown, a method for preparing low-phosphorus, low-sulfur, high-manganese steel is provided, the method comprising:

[0036] S1. Desulfurize the molten iron to a preset sulfur content to obtain desulfurized molten iron;

[0037] S2. The desulfurized molten iron is subjected to dephosphorization treatment with a first preset phosphorus content to obtain dephosphorized semi-steel;

[0038] S3. The dephosphorized semi-steel is decarburized and dephosphorized with a second preset phosphorus content to obtain manganese-containing steel liquid;

[0039] S4. The manganese-containing molten steel is refined, then subjected to vacuum degassing, and then cast to obtain a low-phosphorus, low-sulfur, high-manganese steel billet.

[0040] In the decarburization and dephosphorization smelting process, a first manganese raw material is added, and in the refining process, a second manganese raw material is added.

[0041] The phosphorus content of the first manganese raw material is ≤0.015%, the phosphorus content of the second manganese raw material is ≤0.005%, and the phosphorus content of the desulfurized molten iron is ≤0.08%.

[0042] In this embodiment of the application, the positive effect of the phosphorus content of the first manganese raw material being ≤0.015% is that within this phosphorus content range, it can ensure that the phosphorus element introduced due to the addition of the first manganese raw material is reduced during the decarburization and dephosphorization smelting stage, thereby achieving low phosphorus content control of the dephosphorized semi-steel. When the phosphorus content is greater than the endpoint of this range, the addition of the first manganese raw material will lead to an increase in the phosphorus content of the dephosphorized semi-steel, affecting the low phosphorus content control of the steel billet.

[0043] The positive effect of having a phosphorus content of ≤0.005% in the second manganese raw material is that within this range, it can ensure that the phosphorus element introduced by the addition of the second manganese raw material is reduced during the refining stage, thus achieving low phosphorus content control in manganese-containing molten steel. When the phosphorus content is greater than the endpoint of this range, the addition of the second manganese raw material will lead to an increase in the phosphorus content of manganese-containing molten steel, affecting the low phosphorus content control of the billet.

[0044] The positive effect of having a phosphorus content of ≤0.08% in desulfurized molten iron is that within this range, the subsequent dephosphorization treatment of the desulfurized molten iron can be guaranteed to be complete, thereby ensuring that the dephosphorized semi-steel reaches the expected phosphorus content. When the phosphorus content is greater than the endpoint of this range, it will result in an excessively high phosphorus content in the desulfurized molten iron, leading to an increase in the phosphorus content of the final manganese-containing molten steel, which will affect the control of the low phosphorus content of the steel billet.

[0045] In some optional embodiments, the first manganese raw material needs to be preheated before being added, and the second manganese raw material needs to be preheated before being added.

[0046] The first preheating includes preheating by ladle baking or iron ladle baking, and the second preheating includes preheating by ladle baking or iron ladle baking.

[0047] In this embodiment, unlike the traditional high-manganese steel smelting stage which requires a heating furnace to melt the raw materials, only the first and second manganese raw materials need to be preheated by baking in a steel ladle or iron ladle. This not only reduces energy consumption but also increases the addition temperature of the manganese raw material alloy, thereby increasing the amount of manganese raw materials added.

[0048] In some alternative implementations, the final temperature of the first preheating is >800°C, and the final temperature of the second preheating is >800°C.

[0049] In this embodiment of the application, the positive effect of the first preheating endpoint temperature being >800°C is that within this temperature range, the furnace entry temperature of the first manganese raw material can be increased, thereby increasing the amount of the first manganese raw material added.

[0050] The positive effect of setting the final temperature of the second preheating to >800℃ is that within this temperature range, the furnace feed temperature of the second manganese raw material can be increased, thereby increasing the amount of the second manganese raw material added during the refining stage.

[0051] In some optional embodiments, the first manganese raw material includes at least one of manganese ore, high-carbon ferromanganese alloy, and medium-carbon ferromanganese alloy, and the second manganese raw material includes at least one of carbon ferromanganese alloy, low-carbon ferromanganese alloy, micro-carbon ferromanganese alloy, and metallic manganese.

[0052] In this embodiment of the application, the positive effect of limiting the types of the first manganese raw material and the second manganese raw material is that within this range, the first manganese raw material and the second manganese raw material not only help to increase the manganese content in the molten steel, but also reduce the pressure of subsequent alloy adjustment.

[0053] In some optional embodiments, the manganese content of the manganese-containing molten steel is 10% to 20%.

[0054] In this embodiment of the application, the positive effect of having a manganese content of 10% to 20% in the molten steel is that within this range, the pressure of adjusting the manganese element during the refining process can be reduced.

[0055] In some optional embodiments, the amount of desulfurized molten iron fed into the dephosphorization treatment is 70% to 90% of the amount of molten steel before casting;

[0056] The first manganese raw material is added at a rate of 0.1 t / ton of molten steel to 0.25 t / ton of molten steel, and the second manganese raw material is added at a rate of...

[0057] = [(Target value of Mn element in the billet - Mn element content of the manganese-containing molten steel entering the station) × Total weight of manganese-containing molten steel + Target value of Mn element in the billet × Weight of the second manganese raw material)] / (Recovery rate of the second manganese raw material × Mn element content in the second manganese raw material) ± 0.01t / ton of molten steel.

[0058] In this embodiment of the application, the positive effect of the desulfurized molten iron feed amount in dephosphorization smelting being 70% to 90% of the molten steel amount before casting is that it is beneficial to control the amount of molten steel after refining and to ensure the smooth operation of the process; when the value of this percentage is greater than or less than the endpoint of this range, the adverse effect will be that it will affect the control of the amount of molten steel and the smooth operation of the process.

[0059] The positive effect of adding the first manganese raw material at a rate of 0.1t / ton to 0.25t / ton of molten steel is that within this range, the secondary dephosphorization can be carried out smoothly, while ensuring that the absorption rate of the manganese raw material is within an appropriate range. If the amount of the first manganese raw material added is greater than or less than the endpoint of this range, it will result in an excessive amount of the first manganese raw material added, which will reduce the absorption rate of manganese and cause waste of the first manganese raw material. Alternatively, if the amount of the first manganese raw material added is too low, it will result in an excessively high endpoint temperature in the decarburization converter, which is not conducive to secondary dephosphorization.

[0060] The calculation formula for limiting the amount of the second manganese raw material can accurately obtain the theoretical value of the amount of the second manganese raw material to be added. Then, the error is made up by 0.01t / ton of molten steel, thereby ensuring the accuracy of the amount of the second manganese raw material to be added.

[0061] In some alternative embodiments, the first manganese raw material is added before the dephosphorized semi-steel undergoes the decarburization and dephosphorization smelting, and the second manganese raw material is added when the manganese-containing molten steel is heated to 1500°C during the refining stage.

[0062] In this embodiment of the application, the positive effect of limiting the timing of adding the first manganese raw material is to ensure that the dephosphorized semi-steel is added to the manganese raw material first, and then decarburized and dephosphorized, so as to minimize the impact of impurities in the manganese raw material on the dephosphorized semi-steel.

[0063] The positive effect of limiting the timing of adding the second manganese raw material is that it can ensure that the temperature of the molten steel is within a suitable range after the addition of the second manganese raw material, while ensuring the fluidity of the molten steel. When the temperature value is lower than the endpoint of the range, the refining temperature will be too low. After the addition of the second manganese raw material, the temperature of the molten steel will decrease, resulting in the molten steel solidifying and forming a crust.

[0064] In some optional embodiments, the preset sulfur content is ≤0.002%, the first preset phosphorus content is ≤0.02%, and the second preset phosphorus content is ≤0.005%.

[0065] In this embodiment of the application, the positive effect of setting the sulfur content to ≤0.002% is that within this sulfur content range, the desulfurization load in the refining stage can be guaranteed to be low, which is conducive to the low sulfur control of steel grades, and thus promotes complete desulfurization in the refining stage.

[0066] The positive effect of setting the phosphorus content to ≤0.02% is that within this phosphorus content range, the dephosphorization pressure in the decarburization converter can be reduced, resulting in low-phosphorus molten steel.

[0067] The positive effect of the second preset phosphorus content ≤0.005% is that within this phosphorus content range, the phosphorus content in the manganese-containing molten steel can be guaranteed to be within the expected target, thereby ensuring the dephosphorization effect.

[0068] In some optional embodiments, the decarburization and dephosphorization smelting includes decarburization smelting and dephosphorization smelting. The dephosphorization smelting includes dephosphorization smelting by bottom blowing and stirring with a dephosphorizing agent after the decarburization smelting. The slag removal rate of the dephosphorization smelting is ≥90%. Scrap steel is not added during the dephosphorization smelting and decarburization smelting processes. No auxiliary materials with high sulfur content or high phosphorus content are added during the dephosphorization smelting and decarburization smelting processes. An inert metal alloy is added during the dephosphorization smelting process. The inert metal alloy includes ferrochrome and / or copper alloys.

[0069] In this embodiment of the application, the positive effect of limiting the decarburization and dephosphorization smelting method is that after the decarburization smelting is completed, the low temperature after decarburization in the ladle provides good thermodynamic conditions for dephosphorization, while bottom blowing and stirring provide good kinetic conditions to ensure the subsequent dephosphorization effect.

[0070] The positive effect of not adding scrap steel during dephosphorization and decarburization smelting is that the large amount of high-manganese steel alloy added leads to insufficient heat in the converter. At the same time, the molten iron formed after the scrap steel melts will increase the amount of manganese raw materials added.

[0071] The positive effect of not adding high sulfur and high phosphorus content auxiliary materials during dephosphorization and decarburization smelting is to reduce the sulfur increase and desulfurization and dephosphorization load during the dephosphorization converter smelting and decarburization converter smelting and the refining process, thereby reducing the sulfur and phosphorus content of the finished steel billet.

[0072] The positive effect of a slag removal rate of ≥90% in dephosphorization smelting is that within this range, it can reduce phosphorus reversion from the slag during the refining process.

[0073] In some alternative embodiments, the total amount of the inert metal alloy added is 10t to 15t.

[0074] In this embodiment of the application, the positive effect of adding 10t to 15t of inert metal alloy is that if the amount of inert metal alloy added is small, the final temperature of the dephosphorization converter smelting will be high, which is not conducive to the dephosphorization process; if the amount of inert metal alloy added is large, the final temperature of the dephosphorization converter smelting will be low, and the alloy will not melt sufficiently.

[0075] In some optional embodiments, the vacuum degassing treatment time is 20 min to 30 min, the minimum vacuum degree of the vacuum degassing treatment is <100 Pa, and the degassing device for the vacuum degassing treatment adopts at least one of RH vacuum refining furnace and VD vacuum degassing furnace.

[0076] In this embodiment of the application, the positive effect of a vacuum degassing treatment time of 20 min to 30 min is to ensure sufficient vacuum degassing treatment. If the value of the time is greater than or less than the endpoint of this range, the vacuum degassing treatment time will be too long, resulting in serious loss of manganese in the molten steel under vacuum, leading to a low manganese content in the finished steel billet. Alternatively, if the vacuum degassing treatment time is too short, the vacuum degassing effect will not be achieved.

[0077] The positive effect of a minimum vacuum level of <100Pa in vacuum degassing treatment is to ensure the effectiveness of vacuum degassing.

[0078] In some alternative embodiments, the continuous casting includes slow cooling of the billet with a special protective slag and a special covering agent for high manganese steel.

[0079] In this embodiment, the continuous casting process uses a special protective slag and a special covering agent for high manganese steel for slow cooling treatment. This is beneficial for the smooth production of high manganese steel continuous casting and also helps to reduce cracks and fractures caused by rapid cooling of hot slabs.

[0080] The process parameters for each embodiment and comparative example are shown in Tables 1, 2 and 4.

[0081] Table 1 Process parameters for decarburization smelting

[0082]

[0083] Table 2 Process parameters for dephosphorization smelting

[0084]

[0085]

[0086] Table 3 Process parameters for refining and vacuum degassing treatment

[0087]

[0088] Unless otherwise specified, the process parameters not mentioned in the embodiments and comparative examples other than Example 1 in Tables 1, 2 and 3 should be understood as being consistent with those in Example 1.

[0089] Detailed analysis of Tables 1, 2, and 3:

[0090] The data from Examples 1-3 show that:

[0091] The method described in this application involves dephosphorizing, decarburizing, dephosphorizing, desulfurizing, and degassing the desulfurized molten iron. A first manganese feedstock and a second manganese feedstock are added during the decarburizing and dephosphorizing smelting process and the desulfurization process, respectively. Simultaneously, the phosphorus content of the first and second manganese feedstocks is limited. This not only ensures that the desulfurization process removes sulfur from the molten steel, thereby reducing its sulfur content, but also further reduces the phosphorus content, ensuring that the phosphorus content in the steel billet remains at a lower level than in existing technologies. This achieves the goal of low phosphorus and low sulfur content in high-manganese steel. Without the need for electric arc furnaces or other heating furnaces, only ordinary ladle or iron ladle baking equipment is required to preheat the manganese feedstock. By rationally controlling the feed rate of the desulfurized molten iron and the phosphorus content of the first and second manganese feedstocks, industrial production of low-phosphorus, low-sulfur high-manganese steel with Mn ≥ 10%, P ≤ 0.01%, and S ≤ 0.003% can be achieved.

[0092] From the data in Comparative Examples 1-10, we can see that:

[0093] In Comparative Example 1, if 40 tons of scrap steel are added to the dephosphorization converter, the amount of the first and second manganese raw materials added will be reduced, and the manganese content in the molten steel after decarburization and dephosphorization is 5%, which will result in a lower manganese content in the finished steel billet.

[0094] In Comparative Example 2, if the amount of desulfurized molten iron fed into the dephosphorization treatment is 95% of the amount of molten steel before casting, then the amount of molten steel at the end of the desulfurization and dephosphorization smelting process will be too large, which will prevent the addition of the second manganese raw material during the refining process, resulting in a low manganese content in the finished steel billet.

[0095] In Comparative Example 3, if neither the first manganese raw material nor the second manganese raw material is preheated, the amount of the first manganese raw material and the second manganese raw material added will be small, resulting in a low manganese content in the finished steel billet.

[0096] In Comparative Example 4, if the phosphorus content of the desulfurized molten iron is as high as 0.13%, it will result in a high phosphorus content in the finished steel billet.

[0097] In Comparative Example 5, if high-phosphorus auxiliary materials are added during desulfurization and dephosphorization smelting, the phosphorus in the auxiliary materials will enter the molten steel, resulting in a high phosphorus content in the finished steel billet.

[0098] In Comparative Example 6, if no dephosphorizing agent is added to the ladle to dephosphorize the molten steel, the phosphorus content of the finished steel billet will be too high.

[0099] In Comparative Example 7, if the first and second manganese raw materials with high phosphorus content are used, the phosphorus content of the finished steel billet will be too high.

[0100] In Comparative Example 8, if the dephosphorizing agent is added to the ladle and bottom-blown to remove phosphorus, but the slag is not completely removed, the ladle slag will return to phosphorus, resulting in a high phosphorus content in the finished steel billet.

[0101] In Comparative Example 9, if the vacuum time is too long, it will result in significant loss of manganese and waste of manganese resources.

[0102] In Comparative Example 10, if the vacuum level is not good, the denitrification ability of the molten steel will be poor, resulting in high nitrogen content in the finished product.

[0103] One or more technical solutions in the embodiments of this application have at least the following technical effects or advantages:

[0104] (1) The method provided in this application involves dephosphorizing, decarburizing and dephosphorizing, desulfurizing and degassing the desulfurized molten iron, and adding a first manganese raw material and a second manganese raw material during the decarburizing and dephosphorizing smelting process and the desulfurization process, while limiting the phosphorus content of the first manganese raw material and the second manganese raw material, thereby ensuring that the phosphorus content in the steel billet is maintained at a low level and achieving the goal of low phosphorus content in high manganese steel.

[0105] (2) The method provided in this application embodiment not only controls the phosphorus content of the finished steel billet through the first manganese raw material and the second manganese raw material, but also removes the sulfur element in the molten steel through the subsequent desulfurization process by the addition of manganese raw material, thereby effectively controlling the sulfur content in the molten steel.

[0106] (3) The method provided in this application embodiment is different from the traditional high manganese steel smelting stage, which requires the use of a heating furnace to melt the raw materials. It only requires the first manganese raw material and the second manganese raw material to be preheated by baking in a steel ladle or iron ladle. This not only reduces energy consumption, but also increases the addition temperature of the manganese raw material alloy, thereby increasing the amount of manganese raw material added.

[0107] (4) In this embodiment of the application, by adding the first manganese raw material and the second manganese raw material, the manganese content of the manganese-containing steel liquid after dephosphorization and desulfurization can be increased, thereby realizing the alloy forward movement, thereby reducing the pressure of alloy adjustment in the subsequent stage, avoiding the introduction of a large amount of phosphorus-containing impurities due to frequent subsequent alloy adjustments, and further ensuring that the phosphorus content in the billet is maintained at a low level.

[0108] (5) The method provided in this application embodiment can realize the industrial production of low phosphorus and low sulfur high manganese steel with Mn≥10%, P≤0.01% and S≤0.003%, and improve the performance of high manganese steel, laying the foundation for the application of high manganese steel.

[0109] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0110] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0111] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those 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 invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for producing a low phosphorus, low sulfur, high manganese steel, characterized in that, The method comprises: carrying out desulfurization treatment on the molten iron to obtain desulfurized molten iron with a preset sulfur content; carrying out dephosphorization treatment on the desulfurized molten iron to obtain dephosphorized semi-steel with a first preset phosphorus content; carrying out decarburization and dephosphorization smelting on the dephosphorized semi-steel with a second preset phosphorus content to obtain molten manganese-containing steel; carrying out refining on the molten manganese-containing steel, then carrying out vacuum degassing treatment, and then carrying out pouring to obtain low-phosphorus low-sulfur high-manganese steel billets; wherein a first manganese raw material is added in the decarburization and dephosphorization smelting, and a second manganese raw material is added in the refining; the phosphorus content of the first manganese raw material is ≤0.015%, the phosphorus content of the second manganese raw material is ≤0.005%, and the phosphorus content of the desulfurized molten iron is ≤0.08%; the first manganese raw material is added before the dephosphorized semi-steel is subjected to the decarburization and dephosphorization smelting, and the second manganese raw material is added when the molten manganese-containing steel is heated to 1500°C in the refining stage; the manganese content of the molten manganese-containing steel is 10%-20%; the preset sulfur content is ≤0.002%, the first preset phosphorus content is ≤0.02%, and the second preset phosphorus content is ≤0.005%; the decarburization and dephosphorization smelting comprises decarburization smelting and dephosphorization smelting, the dephosphorization smelting comprises dephosphorization smelting by means of bottom blowing stirring of a dephosphorization agent after the decarburization smelting, and the dephosphorization smelting has a slagging rate ≥90%; the vacuum degassing treatment has a time of 20 min-30 min, and a minimum vacuum degree of the vacuum degassing treatment is <100 Pa; in the low-phosphorus low-sulfur high-manganese steel, Mn≥10%, P≤0.01%, and S≤0.003%.

2. The method of claim 1, wherein, the first manganese raw material also needs to be subjected to first preheating before the first manganese raw material is added, and the second manganese raw material also needs to be subjected to second preheating before the second manganese raw material is added; the first preheating comprises first preheating by means of ladle baking or iron ladle baking, and the second preheating comprises second preheating by means of ladle baking or iron ladle baking.

3. The method of claim 2, wherein, the end point temperature of the first preheating is >800°C, and the end point temperature of the second preheating is >800°C.

4. The production method according to claim 1 or 2, characterized by, the first manganese raw material comprises at least one of manganese ore, high-carbon ferromanganese alloy, and medium-carbon ferromanganese alloy, and the second manganese raw material comprises at least one of carbon ferromanganese alloy, low-carbon ferromanganese alloy, micro-carbon ferromanganese alloy, and metallic manganese.

5. The method of claim 1, wherein, the desulfurized molten iron for the dephosphorization treatment has a feeding amount of 70%-90% of the molten steel liquid amount before the pouring; the first manganese raw material is added in an amount of 0.1 t / t of molten steel-0.25 t / t of molten steel, and the second manganese raw material is added in an amount of=[(the Mn element target value of the steel billet-the Mn element content of the molten manganese-containing steel at the inlet)×the total weight of the molten manganese-containing steel+the Mn element target value of the steel billet×the weight of the second manganese raw material)] / (the yield of the second manganese raw material×the Mn element content in the second manganese raw material)±0.01 t / t of molten steel.

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