Method for producing low-phosphorus and low-sulfur high-manganese steel

Abstract

The invention discloses a method for producing low-phosphorus and low-sulfur high-manganese steel, which belongs to the technical field of metallurgy and comprises the following steps: S1, raw material preparation, S2, electric arc furnace smelting, S3, LF furnace refining, S4, wire feeding, S5, pouring and heat treatment and S6, water toughening treatment. According to the method, the P removal and C preservation operation is carried out in the oxidation period of the electric arc furnace, and traditional high-carbon ferromanganese or medium-carbon ferromanganese is replaced with low-phosphorus electrolytic manganese, so that the P content in the high-manganese steel finished product can be effectively reduced; and the deep desulfurization effect can be realized by performing the S removal operation in the LF refining reduction period. Through electric arc furnace pre-dephosphorization, LF deep desulfurization and staged addition of low-phosphorus manganese raw materials, cooperative control of P and S is achieved, meanwhile, through precise control over various process parameters and raw material optimization, the content of phosphorus and sulfur can be remarkably reduced, the phosphorus content in a high-manganese steel finished product is reduced by 60% compared with a traditional process, and the sulfur content is reduced by 40%.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, and in particular relates to a method for producing low-phosphorus, low-sulfur, high-manganese steel. Background Technology

[0002] Electric arc furnace steelmaking is a steelmaking method that uses electricity as a heat source and scrap steel as the main raw material. It uses an electric arc generated by the discharge between electrodes and furnace charge to convert electrical energy into heat energy in the arc light, heating and melting the metal furnace charge and slag, and smelting steel and alloys of various qualified compositions.

[0003] When producing ZGMn13 in an electric arc furnace, the phosphorus content in the scrap steel fluctuates greatly (0.02-0.04%), and phosphorus (0.20-0.25%) and sulfur (0.03-0.05%) are introduced by the manganese alloy, resulting in excessive P and S content in the finished product, leading to a high risk of low-temperature brittleness and hot cracking. Existing production processes have insufficient dephosphorization efficiency, and LF refining desulfurization is limited by slag volume, making it difficult to simultaneously meet the requirements of P≤0.015% and S≤0.005%. Therefore, we propose a method for producing low-phosphorus, low-sulfur, high-manganese steel to address the aforementioned problems. Summary of the Invention

[0004] In view of this, in order to solve the problems of insufficient dephosphorization efficiency in traditional production processes and the difficulty in simultaneously meeting the standards for P and S content in finished products due to the limitation of slag volume in LF refining desulfurization, this invention provides a method for producing low-phosphorus, low-sulfur, high-manganese steel.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for producing low-phosphorus, low-sulfur, high-manganese steel, comprising the following steps: S1. Raw material preparation: Prepare scrap steel with P≤0.02% and S≤0.02%, electric furnace high carbon ferromanganese and electrolytic manganese with P≤0.12%; S2, Electric Arc Furnace Melting: S21. Charging: 0.6-1.2% lime and 0.3-0.6% iron ore by weight are charged into the furnace bottom, and 0.7-0.8% carbon raiser is charged depending on the condition of the furnace charge; S22, Melting: S221. Add scrap steel in batches. When the furnace charge has melted 60-70% and the temperature is controlled at 1400-1450℃, add 25-35 kg / t of lime and 10-12 kg / t of iron ore, and blow oxygen to assist melting. S222. After the scrap steel is melted, steel samples are taken to analyze the C and P content. Based on the phosphorus content, it is decided whether to remove slag and the amount of slag to remove. New slag is then created after slag removal. S23, Oxidation: S231. Raise the temperature to 1450-1600℃, add 4-6 kg / t of fluorite, and after the slag has good fluidity, carry out oxygen blowing to remove phosphorus, removing 0.2-0.3% carbon, at which point the carbon content is 0.8-1.0%. S232. Stir the molten steel thoroughly, take samples for analysis, and remove slag when P ≤ 0.005%; S24, Restoration: S241. After removing all the oxidized slag, add 2-3 kg / t of pre-deoxidizing agent ferrosilicon and 1-1.5% of thin slag material to make thin slag, and then make calcium carbide slag for reduction for 12-18 minutes. S242. When the slag is in good condition, add electrolytic manganese in batches and add reducing agent in batches, and control the temperature at 1600-1650℃. S243. After the molten steel is thoroughly stirred, a steel sample is taken for full analysis. Then, the molten steel is stirred thoroughly 2-3 times, and a steel sample is taken for full analysis after each stirring. During this process, a reducing agent is continuously added for reduction. Slag samples are taken for analysis under good white slag conditions. The requirement is: (FeO+MnO)≤1.0%; S244. Based on the analysis results of the steel sample, adjust the chemical composition and add ferromanganese for 8-12 minutes before tapping the steel. However, the silicon content must be adjusted before tapping the steel, requiring: 0.30%≤Si≤0.40%. S245. Finally, when the temperature of the molten steel is measured to be within the range of 1520-1540℃, the power is turned off, the electrodes are raised, and the temperature is measured again after stirring. When the temperature of the molten steel is still maintained within the range of 1520-1540℃, the steel can be tapped. S3, LF furnace refining: S31, Slag Forming Desulfurization: S311. First, add 5-10 kg / t of lime and 2-3 kg / t of fluorite to the ladle to form slag; S312. After slag melting is complete, power is supplied to raise the temperature to 1500-1600℃, and 1-2 kg / t of reducing agent is added. Argon is supplied at a high intensity of 140-160 NL / h·t. The molten steel must not be exposed above the slag surface. S313. During the refining process, reducer, lime and refining synthetic slag are added in batches according to the slag condition to maintain white slag as well as the basicity and fluidity of the slag. The total slag amount is maintained at 1.5-2.5% of the molten steel amount, and the white slag is maintained for more than 15 minutes. The final composition of the molten steel obtained through the above steps is: C 1.05-1.15%, Si 0.3-0.4%, Mn 13-14%, P 0.012-0.015%≤0.015%, S 0.003-0.004%≤0.005%; S4. Wire feeding: Calcium-aluminum cored wire is fed into the molten steel at a rate of 10-12 m / t, and argon gas is blown in at the same time. The pressure is controlled at 0.2-0.3 MPa. After the wire feeding is completed, soft blowing is carried out for more than 8 minutes. The molten steel is not allowed to be exposed above the slag surface. S5. Casting and heat treatment: The casting temperature is controlled at 1440-1460℃, and water glass, magnesium olivine sand, and alkaline coating sand molds are used to prevent sand from sticking. S6. Water toughening treatment: The casting is heated to 1040-1060℃ and held for 3-4 hours. The water temperature is ≥950℃ and the water temperature is ≤30℃. After cooling, low phosphorus and low sulfur high manganese steel with P≤0.015% and S≤0.005% is obtained.

[0006] Furthermore, in step S21, the furnace bottom is loaded with 1.1-1.2% lime and 0.5-0.6% iron ore by weight, and 0.7-0.8% carbon raiser is added depending on the ratio of scrap steel plate and scrap rail steel. If the scrap steel plate has a low carbon content and the scrap rail steel has a high carbon content, more carbon raiser is added if the proportion of scrap steel plate is large.

[0007] Furthermore, in step S221, the scrap steel is added in three batches: the first batch adds 60% of the total amount, the second batch adds 30% of the total amount, and the third batch adds the remaining amount.

[0008] Furthermore, in step S221, after all the scrap steel is added, the furnace charge is melted by two-thirds, the temperature is controlled at 1400℃, and 30 kg / t of lime is added.

[0009] Furthermore, in step S222, a phosphorus content exceeding 0.018% is considered too high. The size of the slag flow is determined based on the condition of the slag and molten steel in the furnace, while lime and ore are added to the new slag according to the phosphorus composition.

[0010] Furthermore, the oxidation process in step S231 raises the temperature to 1450°C.

[0011] Furthermore, in step S232, after oxidation for 10-20 minutes, the molten steel is thoroughly stirred and sampled for analysis. If the requirements are not met, the chemical composition of the sample is analyzed every 5-10 minutes until P ≤ 0.005% is met, and then the slag is removed.

[0012] Furthermore, in step S312, after the slag has been melted, the temperature is raised to 1550°C by power supply, and argon is supplied at a high intensity of 150 NL / h·t to promote the reaction at the steel-slag interface and promote desulfurization.

[0013] Furthermore, in step S313, lime, refining slag and reducing agent are added in batches according to the alkalinity, quantity and fluidity of the slag. During the addition process, lime and refining slag are added first, and an appropriate amount of reducing agent is added at the same time. In the later stage, only a small amount of reducing agent needs to be added to maintain the reducing atmosphere.

[0014] Furthermore, in step S4, the first 9 tons of molten steel are fed with wire at a rate of 10m / t, and after 9 tons, an additional 10m of wire is fed for every 1 t exceeding 9 tons.

[0015] The embodiments of the present invention have the following beneficial effects: This invention effectively reduces the phosphorus (P) content in high-manganese steel by performing a phosphorus removal and carbon preservation operation during the electric arc furnace oxidation period and replacing traditional high-carbon or medium-carbon ferromanganese with low-phosphorus electrolytic manganese. Furthermore, it achieves deep desulfurization through a sulfur removal operation during the LF refining and reduction period. By employing pre-phosphorus removal in the electric arc furnace, deep desulfurization in the LF process, and the phased addition of low-phosphorus manganese raw materials, synergistic control of P and S is achieved. Simultaneously, through precise control of various process parameters and raw material optimization, the phosphorus and sulfur content can be significantly reduced. Compared to traditional processes, the phosphorus content in the high-manganese steel product is reduced by 60%, and the sulfur content by 40%.

[0016] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Detailed Implementation

[0017] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0018] Example 1: This example provides a method for producing low-phosphorus, low-sulfur, high-manganese steel. First, a test is conducted on removing phosphorus from the slag added to the furnace bottom. This test method includes the following steps: The first step is to prepare scrap steel with P≤0.02% and S≤0.02%. The scrap steel can be scrap steel plate with low carbon content, scrap rail steel with high carbon content, or a mixture of the two in a certain proportion.

[0019] The second step involves smelting the scrap steel using an electric arc furnace: First, 0.6-0.7% lime and 0.3-0.4% iron ore by weight are charged into the furnace bottom. The scrap steel is added in three batches: the first batch contains 60% of the total, the second batch contains 30%, and during the second batch, if the scrap steel is of suitable size, it can be added entirely; otherwise, the remaining scrap steel is added in the third batch. After the scrap steel is added and the furnace charge has melted, the solution is analyzed. At this point, the phosphorus content is 0.018%, which is greater than 0.015% and does not meet production requirements.

[0020] Example 2: This example is a further improvement on Example 1: A second test was conducted on the dephosphorization of the slag material at the bottom of the furnace. With the iron ore dosage unchanged, the lime dosage was increased to 0.8-0.9%. At this time, the P content in the molten material was 0.017%, which was reduced by 0.001% compared to Example 1, but was still greater than 0.015%, which did not meet the production requirements.

[0021] Example 3: This example is a further improvement on Example 2: a third test was conducted on the dephosphorization of the bottom slag material. With the iron ore dosage unchanged, the lime dosage was increased to 1.1-1.2%. At this time, the P content in the molten material was 0.015%, which was 0.002% lower than that in Example 2, showing a significant improvement. However, it was still not lower than 0.015%, but it basically met the production requirements.

[0022] Example 4: This example is a further improvement on Example 3: The fourth test was conducted on the dephosphorization of the slag material at the bottom of the furnace. With the amount of lime unchanged, the amount of iron ore was increased to 0.5-0.6%. At this time, the P content in the molten metal was 0.012%, which was reduced by 0.003% compared to Example 3, and was lower than 0.015%, which fully met the production requirements.

[0023] Taking 10 tons of steel as an example, the test data comparison of Examples 1-4 is shown in the table below: Example Lime (kg) Iron ore (kg) P content in melt-clear liquid (%) 1 60-70 30-40 0.018 2 80-90 30-40 0.017 3 110-120 30-40 0.015 4 110-120 50-60 0.012 According to the comparison table, using 0.6-0.7% lime with 0.3-0.4% iron ore represents the original production process, producing a phosphorus (P) content of 0.018% ≥ 0.015%, which does not meet the low-phosphorus production requirements of this invention. However, with the lime content continuously increasing while the iron ore content remains constant, the P content shows a clear decreasing trend. When the lime content increases to 1.1-1.2%, the P content is already equal to 0.015%, which basically meets the production requirements of this invention. To pursue better production quality and better meet the low-phosphorus production requirements, a fourth experiment was conducted. The results of the fourth experiment show that, with the lime content unchanged, increasing the iron ore content to 0.5-0.6% significantly improved the P content, reducing it by 0.003%, a substantial decrease to 0.012%, less than 0.015%, which fully meets the production requirements of this invention. Therefore, subsequent production and processing methods for high-manganese steel will all follow the experimental method of Example 4.

[0024] Example 5: This example provides a method for producing low-phosphorus, low-sulfur, high-manganese steel. Combined with the experimental method of Example 4, an experiment was conducted on slag addition during the molten oxide stage. This experimental method includes the following steps: The first step is to prepare scrap steel with P≤0.02% and S≤0.02%. The scrap steel can be scrap steel plate with low carbon content, scrap rail steel with high carbon content, or a mixture of the two in a certain proportion.

[0025] The second step is to smelt the scrap steel using an electric arc furnace. First, charge the furnace bottom with 1.1-1.2% lime and 0.5-0.6% iron ore by weight. Then, add 0.7-0.8% recarburizer, depending on the furnace charge composition, based on the ratio of scrap steel plates to scrap rail steel. Add more recarburizer when the proportion of low-carbon scrap steel plates is higher, and vice versa.

[0026] The scrap steel was then added in three batches. The first batch added 60% of the total amount, the second batch added 30%, and during the second batch, if the scrap steel size was suitable, it could be added entirely; otherwise, the remaining scrap steel was added in the third batch. After the scrap steel was added and the furnace charge melted, the solution was taken for testing and analysis. At this point, the phosphorus content was 0.012%.

[0027] After adding scrap steel in batches, once two-thirds of the furnace charge has melted and the temperature is controlled at 1400℃, add 25 kg / t of lime and 10-12 kg / t of iron ore, preferably 10 kg / t of iron ore. Oxygen is blown to aid melting, and slag is formed in advance to promote phosphorus removal. After the scrap steel melts, steel samples are taken to analyze the C and P content. Based on the phosphorus content, the decision is made regarding whether to add slag and the amount of slag to be added. A phosphorus content exceeding 0.018% is considered high. The amount of slag to be added is determined by visually observing the slag and molten steel in the furnace. After adding slag, new slag should be formed, with lime and ore added to the new slag according to its phosphorus composition.

[0028] Next, the furnace temperature is raised to 1560℃, and 4-6 kg / t of fluorite is added to adjust the slag fluidity, preferably 5 kg / t. When the slag fluidity is good, oxygen blowing for phosphorus removal is performed, with carbon removal at 0.2-0.3% and carbon content at 0.8-1.0%. After oxidation for 10-20 minutes, the molten steel is thoroughly stirred, and samples are taken for analysis. If the requirements are not met, samples are taken again every 5-10 minutes based on the chemical composition of the samples. Finally, the phosphorus content at the end of oxidation is maintained at 0.01%, which is much greater than 0.005% and does not meet production requirements.

[0029] Example 6: This example is a further improvement on Example 5: A second test was conducted on the slag addition during the molten oxidation period. The amount of lime was increased to 30 kg / t, while the temperature and the amount of iron ore and fluorite added remained unchanged. After sampling and analysis, the C content remained unchanged at 0.8-1.0%, while the P content at the end of the final oxidation period remained at 0.008%, which is still greater than 0.005%, and does not meet the production requirements.

[0030] Example 7: This example is a further improvement on Example 6: A third test was conducted on the slag addition material during the molten oxidation period. The amount of lime was increased to 35 kg / t, while the temperature and the amount of iron ore and fluorite added remained unchanged. After sampling and analysis, the C content remained unchanged at 0.8-1.0%, while the P content at the end of the final oxidation period was still 0.008%, which is still greater than 0.005%, and does not meet the production requirements.

[0031] Example Lime (kg) Iron ore (kg) Carbon raiser (kg) P content in melt-clear liquid (%) Amount of lime residue added (kg) Oxidation temperature (°C) P content at the end of oxidation (%) Melting point C content (%) 5 110-120 50-60 70-80 0.12 250 1560 0.01 0.8-1.0 6 110-120 50-60 70-80 0.12 300 1560 0.008 0.8-1.0 7 110-120 50-60 70-80 0.12 350 1560 0.008 0.8-1.0 According to the comparison table, based on the experimental method of Example 4, by adding 1.1-1.2% lime and 0.5-0.6% iron ore by weight to the furnace bottom, and adding 0.7-0.8% carburizing agent depending on the furnace charge, the carburizing agent had no effect on phosphorus removal, so it was not added in the experiment of dephosphorizing with slag at the furnace bottom. Simultaneously, by controlling the temperature and keeping the amounts of iron ore and fluorite constant, the amount of lime slag added was increased sequentially. When the lime dosage was 25 kg / t, the phosphorus content at the end of oxidation was relatively high, reaching 0.01%. When the dosage was increased to 30 kg / t, the phosphorus content at the end of oxidation decreased significantly to 0.008%, but still did not meet the requirement of less than 0.005%. By increasing the dosage again to 35 kg / t, the phosphorus content at the end of oxidation remained at 0.008%, without decreasing. Based on three tests on slag addition during the molten oxide period, the optimal amount of lime added was determined to be 30 kg / t. Therefore, the subsequent production and processing methods for high manganese steel were all carried out using the test method of Example 6.

[0032] Example 8: This example provides a method for producing low-phosphorus, low-sulfur, high-manganese steel. Combining the experimental method of Example 6, the dephosphorization at the oxidation temperature during the melting and oxidation period is tested. This experimental method includes the following steps: The first step is to prepare scrap steel with P≤0.02% and S≤0.02%. The scrap steel can be scrap steel plate with low carbon content, scrap rail steel with high carbon content, or a mixture of the two in a certain proportion.

[0033] The second step is to smelt the scrap steel using an electric arc furnace. First, charge the furnace bottom with 1.1-1.2% lime and 0.5-0.6% iron ore by weight. Then, add 0.7-0.8% recarburizer, depending on the furnace charge composition, based on the ratio of scrap steel plates to scrap rail steel. Add more recarburizer when the proportion of low-carbon scrap steel plates is higher, and vice versa.

[0034] The scrap steel was then added in three batches. The first batch added 60% of the total amount, the second batch added 30%, and during the second batch, if the scrap steel size was suitable, it could be added entirely; otherwise, the remaining scrap steel was added in the third batch. After the scrap steel was added and the furnace charge melted, the solution was taken for testing and analysis. At this point, the phosphorus content was 0.012%.

[0035] After adding scrap steel in batches, once two-thirds of the furnace charge has melted and the temperature is controlled at 1400℃, add 30 kg / t of lime and 10-12 kg / t of iron ore, preferably 10 kg / t of iron ore. Oxygen is blown to aid melting, and slag is formed in advance to promote phosphorus removal. After the scrap steel melts, steel samples are taken to analyze the C and P content. Based on the phosphorus content, the decision is made regarding whether to add slag and the amount of slag to be added. A phosphorus content exceeding 0.018% is considered high. The amount of slag to be added is determined by visually observing the slag and molten steel in the furnace. After adding slag, new slag should be formed, with lime and ore added to the new slag according to its phosphorus composition.

[0036] Next, the furnace temperature is raised to 1500℃, and 4-6 kg / t of fluorite is added to adjust the slag fluidity, preferably 5 kg / t. When the slag fluidity is good, oxygen blowing for phosphorus removal is performed, with carbon removal at 0.2-0.3% and carbon content at 0.8-1.0%. After oxidation for 10-20 minutes, the molten steel is thoroughly stirred, and samples are taken for analysis. If the requirements are not met, samples are taken again every 5-10 minutes based on the chemical composition of the samples. Finally, the phosphorus content at the end of oxidation is maintained at 0.006%, close to 0.005%, but still greater than 0.005%, which still does not meet production requirements.

[0037] Example 9: This example is a further improvement on Example 8: A second experiment was conducted on the dephosphorization process during the molten oxygen oxidation stage. With the other methods remaining unchanged, the furnace temperature was raised to 1450℃, fluorite was added, and oxygen was blown to remove P. Sampling analysis showed that the carbon content was 0.8-1.0%, while the P content at the final oxidation stage remained at 0.003%, less than 0.005%, fully meeting production requirements.

[0038] Example Lime (kg) Iron ore (kg) Carbon raiser (kg) P content in melt-clear liquid (%) Amount of lime residue added (kg) Oxidation temperature (°C) P content at the end of oxidation (%) Melting agent C content (%) 6 110-120 50-60 70-80 0.12 300 1560 0.008 0.8-1.0 8 110-120 50-60 70-80 0.12 300 1500 0.006 0.8-1.0 9 110-120 50-60 70-80 0.12 350 1450 0.003 0.8-1.0 According to the comparison table, based on the experimental method of Example 6, by changing the temperature control, increasing the melting temperature from 1400℃ to 1450℃ before adding fluorite, and then performing oxygen blowing to remove phosphorus, the phosphorus content at the end of the oxidation process can be reduced to 0.003%, which is less than the 0.005% requirement of this invention. Therefore, subsequent production and processing methods for high-manganese steel will all follow the experimental method of Example 9.

[0039] Example 10: This example provides a method for producing low-phosphorus, low-sulfur, high-manganese steel, based on the experimental method of Example 9, including the following steps: The first step is to prepare scrap steel with P≤0.02% and S≤0.02%, and electric furnace high carbon ferromanganese and electrolytic manganese with P≤0.12%. The scrap steel can be scrap steel plate with low carbon content, scrap rail steel with high carbon content, or a mixture of the two in a certain proportion.

[0040] The second step is to smelt the scrap steel using an electric arc furnace. Charging: First, add 1.1-1.2% lime and 0.5-0.6% iron ore by weight to the bottom of the furnace. Then, add 0.7-0.8% recarburizer depending on the furnace charge, based on the ratio of scrap steel plates to scrap rail steel. Add more recarburizer when the proportion of low-carbon scrap steel plates is higher, and vice versa.

[0041] Melting: Then, the scrap steel is added in three batches. The first batch contains 60% of the total amount, the second batch contains 30%, and during the second batch, if the scrap steel size is suitable, it can be added entirely. If the scrap steel size is not suitable, the remaining scrap steel is added in the third batch. After the scrap steel is added and the furnace charge has melted, the solution is taken for testing and analysis. At this point, the phosphorus content is 0.012%.

[0042] After adding scrap steel in batches, once two-thirds of the furnace charge has melted and the temperature is controlled at 1400℃, add 30 kg / t of lime and 10-12 kg / t of iron ore, preferably 10 kg / t of iron ore. Oxygen is blown to aid melting, and slag is formed in advance to promote phosphorus removal. After the scrap steel melts, steel samples are taken to analyze the C and P content. Based on the phosphorus content, the decision is made regarding whether to add slag and the amount of slag to be added. A phosphorus content exceeding 0.018% is considered high. The amount of slag to be added is determined by visually observing the slag and molten steel in the furnace. After adding slag, new slag should be formed, with lime and ore added to the new slag according to its phosphorus composition.

[0043] Oxidation: Next, raise the furnace temperature to 1450℃ and add 4-6 kg / t of fluorite to adjust the slag fluidity, preferably 5 kg / t. When the slag fluidity is good, perform oxygen blowing to remove phosphorus (P), with a carbon removal rate of 0.2-0.3% and a carbon content of 0.8-1.0%. After oxidation for 10-20 minutes, thoroughly stir the molten steel and take samples for analysis. If the requirements are not met, take samples again every 5-10 minutes based on the chemical composition of the samples. Finally, maintain the P content at the end of oxidation at 0.003% (less than 0.005%), then skim off the slag. By adopting a "low temperature, high basicity" process, the temperature is controlled at 1400-1450℃ and the slag basicity is... With the addition of oxygen blowing and stirring, as well as multiple slag replacement operations, the dephosphorization rate is ≥70%.

[0044] Reduction: After removing all the oxidized slag, add 2-3 kg / t of pre-deoxidizing agent ferrosilicon and 1-1.5% of thin slag material to create a thin slag. Then, reduce with calcium carbide slag for 12-18 minutes, preferably 15 minutes. Add electrolytic manganese in batches, along with the reducing agent, while controlling the temperature at 1600-1650℃. After the molten steel is clear, stir it thoroughly and take a sample for complete analysis. Then, stir the molten steel thoroughly 2-3 more times, taking a sample after each stirring for complete analysis. During this process, the reducing agent should be continuously added for reduction. Take slag samples for analysis under good white slag conditions, requiring (FeO+MnO) ≤ 1.0%.

[0045] Then, based on the analysis results of the steel sample, the chemical composition is adjusted, and ferromanganese is added for 8-12 minutes before tapping. However, the silicon content must be adjusted before tapping, requiring: 0.30%≤Si≤0.40%. Finally, when the temperature of the molten steel is measured to be within the range of 1520-1540℃, the power is turned off, the electrodes are raised, and the temperature is measured again after stirring. When the temperature of the molten steel is still maintained within the range of 1520-1540℃, the steel can be tapped.

[0046] The third step is to refine the molten steel using an LF furnace: Slag-forming desulfurization: First, add 5-10 kg / t of lime and 2-3 kg / t of fluorite to the ladle for slag formation. After slag formation is complete, power is supplied to raise the temperature to 1500-1600℃, preferably 1550℃, and 1-2 kg / t of reducing agent is added. High-intensity argon supply is used at 140-160 NL / h·t, preferably 150 NL / h·t. The molten steel must not be exposed above the slag surface to promote the steel-slag interface reaction and facilitate desulfurization.

[0047] During the refining process, reducing agent, lime, and refining synthetic slag are added in batches according to the slag's basicity, quantity, and fluidity to maintain white slag and its basicity and fluidity. In the initial addition, lime and refining synthetic slag are added first, along with an appropriate amount of reducing agent. Later, only a small amount of reducing agent is added to maintain the reducing atmosphere. The total slag quantity is maintained at 1.5-2.5% of the molten steel quantity, and the white slag is maintained for more than 15 minutes.

[0048] The final composition of the molten steel obtained through the above steps is: C 1.05-1.15%, Si 0.3-0.4%, Mn 13-14%, P 0.012-0.015%≤0.015%, and S 0.003-0.004%≤0.005%.

[0049] Step 4: Wire Feeding: Calcium-aluminum cored wire is fed into the molten steel at a rate of 10-12 m / t. Ideally, the first 9 tons of molten steel should be fed at a rate of 10 m / t. For each additional ton of molten steel beyond 9 tons, an additional 10 m of wire should be fed. Argon gas is simultaneously introduced, with the pressure controlled at 0.2-0.3 MPa. After wire feeding, soft blowing continues for at least 8 minutes, ensuring the molten steel does not expose the slag surface. This process creates white slag. By combining calcium feeding wire with strong argon blowing, the desulfurization rate is ≥80%.

[0050] Step 5, Casting and Heat Treatment: The casting temperature is controlled at 1440-1460℃, and water glass, magnesium olivine sand, and alkaline coating sand mold are used to prevent sand from sticking.

[0051] Step 6, Water toughening treatment: Heat the casting to 1040-1060℃ and hold for 3-4 hours. Immerse it in water at a temperature ≥950℃ and a water temperature ≤30℃. After cooling, low phosphorus and low sulfur high manganese steel with P≤0.015% and S≤0.005% is obtained.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for producing low-phosphorus, low-sulfur, high-manganese steel, characterized in that, Includes the following steps: S1. Raw material preparation: Prepare scrap steel with P≤0.02% and S≤0.02%, electric furnace high carbon ferromanganese and electrolytic manganese with P≤0.12%; S2, Electric Arc Furnace Melting: S21. Charging: 0.6-1.2% lime and 0.3-0.6% iron ore by weight are charged into the furnace bottom, and 0.7-0.8% carbon raiser is charged depending on the condition of the furnace charge; S22, Melting: S221. Add scrap steel in batches. When the furnace charge has melted 60-70% and the temperature is controlled at 1400-1450℃, add 25-35 kg / t of lime and 10-12 kg / t of iron ore, and blow oxygen to assist melting. S222. After the scrap steel is melted, steel samples are taken to analyze the C and P content. Based on the phosphorus content, it is decided whether to remove slag and the amount of slag to remove. New slag is then created after slag removal. S23, Oxidation: S231. Raise the temperature to 1450-1600℃, add 4-6 kg / t of fluorite, and after the slag has good fluidity, carry out oxygen blowing to remove phosphorus, removing 0.2-0.3% carbon, at which point the carbon content is 0.8-1.0%. S232. Stir the molten steel thoroughly, take samples for analysis, and remove slag when P ≤ 0.005%; S24, Restoration: S241. After removing all the oxidized slag, add 2-3 kg / t of pre-deoxidizing agent ferrosilicon and 1-1.5% of thin slag material to make thin slag, and then make calcium carbide slag for reduction for 12-18 minutes. S242. When the slag is in good condition, add electrolytic manganese in batches and add reducing agent in batches, and control the temperature at 1600-1650℃. S243. After the molten steel is thoroughly stirred, a steel sample is taken for full analysis. Then, the molten steel is stirred thoroughly 2-3 times, and a steel sample is taken for full analysis after each stirring. During this process, a reducing agent is continuously added for reduction. Slag samples are taken for analysis under good white slag conditions. The requirement is: (FeO+MnO)≤1.0%; S244. Based on the analysis results of the steel sample, adjust the chemical composition and add ferromanganese for 8-12 minutes before tapping the steel. However, the silicon content must be adjusted before tapping the steel, requiring: 0.30%≤Si≤0.40%. S245. Finally, when the temperature of the molten steel is measured to be within the range of 1520-1540℃, the power is turned off, the electrodes are raised, and the temperature is measured again after stirring. When the temperature of the molten steel is still maintained within the range of 1520-1540℃, the steel can be tapped. S3, LF furnace refining: S31, Slag Forming Desulfurization: S311. First, add 5-10 kg / t of lime and 2-3 kg / t of fluorite to the ladle to form slag; S312. After slag melting is complete, power is supplied to raise the temperature to 1500-1600℃, and 1-2 kg / t of reducing agent is added. Argon is supplied at a high intensity of 140-160 NL / h·t. The molten steel must not be exposed above the slag surface. S313. During the refining process, reducer, lime and refining synthetic slag are added in batches according to the slag condition to maintain white slag as well as the basicity and fluidity of the slag. The total slag amount is maintained at 1.5-2.5% of the molten steel amount, and the white slag is maintained for more than 15 minutes. The final composition of the molten steel obtained through the above steps is: C 1.05-1.15%, Si 0.3-0.4%, Mn 13-14%, P 0.012-0.015%≤0.015%, S 0.003-0.004%≤0.005%; S4. Wire feeding: Calcium-aluminum cored wire is fed into the molten steel at a rate of 10-12 m / t, and argon gas is blown in at the same time. The pressure is controlled at 0.2-0.3 MPa. After the wire feeding is completed, soft blowing is carried out for more than 8 minutes. The molten steel is not allowed to be exposed above the slag surface. S5. Casting and heat treatment: The casting temperature is controlled at 1440-1460℃, and water glass, magnesium olivine sand, and alkaline coating sand molds are used to prevent sand from sticking. S6. Water toughening treatment: The casting is heated to 1040-1060℃ and held for 3-4 hours. The water temperature is ≥950℃ and the water temperature is ≤30℃. After cooling, low phosphorus and low sulfur high manganese steel with P≤0.015% and S≤0.005% is obtained.

2. The method for producing low-phosphorus, low-sulfur, high-manganese steel as described in claim 1, characterized in that, In step S21, the furnace bottom is loaded with 1.1-1.2% lime and 0.5-0.6% iron ore by weight, and 0.7-0.8% carbon raiser is added depending on the ratio of scrap steel plate and scrap rail steel. If the scrap steel plate has a low carbon content and the scrap rail steel has a high carbon content, more carbon raiser is added if the proportion of scrap steel plate is large.

3. The method for producing low-phosphorus, low-sulfur, high-manganese steel as described in claim 2, characterized in that, In step S221, the scrap steel is added in three batches: the first batch adds 60% of the total amount, the second batch adds 30% of the total amount, and the third batch adds the remaining amount.

4. The method for producing low-phosphorus, low-sulfur, high-manganese steel as described in claim 3, characterized in that, In step S221, after all the scrap steel is added, wait until two-thirds of the furnace charge has melted, control the temperature at 1400℃, and add 30 kg / t of lime.

5. The method for producing low-phosphorus, low-sulfur, high-manganese steel as described in claim 4, characterized in that, In step S222, a phosphorus content exceeding 0.018% is considered too high. The size of the slag flow is determined based on the condition of the slag and molten steel in the furnace, while lime and ore are added to the new slag according to the phosphorus composition.

6. The method for producing low-phosphorus, low-sulfur, high-manganese steel as described in claim 5, characterized in that, The oxidation process in step S231 raises the temperature to 1450°C.

7. A method for producing low-phosphorus, low-sulfur, high-manganese steel as described in claim 6, characterized in that, In step S232, after oxidation for 10-20 minutes, the molten steel is thoroughly stirred and sampled for analysis. If the requirements are not met, the chemical composition of the sample is analyzed every 5-10 minutes until P ≤ 0.005% is met, and then the slag is removed.

8. A method for producing low-phosphorus, low-sulfur, high-manganese steel as described in claim 1 or 7, characterized in that, In step S312, after the slag is melted, the temperature is raised to 1550℃ by power supply, and argon is supplied at a high intensity of 150NL / h·t to promote the reaction at the steel-slag interface and promote desulfurization.

9. A method for producing low-phosphorus, low-sulfur, high-manganese steel as described in claim 8, characterized in that, In step S313, lime, refined synthetic slag and reducing agent are added in batches according to the alkalinity, quantity and fluidity of the slag. During the addition process, lime and refined synthetic slag are added first, and an appropriate amount of reducing agent is added at the same time. In the later stage, only a small amount of reducing agent needs to be added to maintain the reducing atmosphere.

10. A method for producing low-phosphorus, low-sulfur, high-manganese steel as described in claim 1, characterized in that, In step S4, the first 9 tons of molten steel are fed wire at a rate of 10m / t. After 9 tons, an additional 10m of wire is fed for every 1 t exceeding the limit.