Process for preparing nitrogen-containing high manganese steel by blowing nitrogen in medium frequency furnace

Abstract

The present invention discloses a process for preparing nitrogen-containing high manganese steel by blowing nitrogen in a medium frequency furnace, comprising the following steps: (1) knotting a crucible; (2) designing and manufacturing a gas diffuser; (3) connecting a nitrogen blowing system; (4) preparing materials; (5) adding materials for smelting; (6) adjusting chemical composition; (7) sedation in the furnace; and (8) temperature-controlled steel tapping. The nitrogen-containing high manganese steel prepared by the present invention has an elongation of more than 24%, and both oxygen and hydrogen contents are less than 10 ppm, indicating that the nitrogen-containing high manganese steel prepared by the process of the present invention has extremely high purity and excellent performance, and can meet the requirements of being used in the production of wear-resistant parts of large cone and jaw crushers, as well as other parts that are subject to large impact loads and require wear resistance, and is of great significance.

Description

Technical Field

[0001] The invention belongs to the technical field of high manganese steel preparation, and specifically relates to a process for preparing nitrogen-containing high manganese steel by blowing nitrogen in a medium frequency furnace. Background Art

[0002] After more than a hundred years of development, high manganese steel has formed several series such as manganese 13, manganese 18 and manganese 25. Among them, manganese 13 has formed international and domestic standards and is relatively mature. Manganese 18 only has international standards, and manganese 25 is difficult to make, so it only has internal enterprise standards for the time being. Research on high manganese steel at home and abroad has never stopped, mainly focusing on alloying, purity and heat treatment. At present, in the field of alloying research, metal elements are mainly used. In terms of non-metallic element research and development, it is still in the exploratory stage, and no stable process plan has been formed. One of the main reasons is that the stability of non-metallic element content and the addition process cannot be solved. In terms of purity, suitable process and tooling specifications have not yet been formed.

[0003] One of the main reasons for choosing nitrogen as a non-metal alloy is that nitrogen has the same properties as manganese in high manganese steel. The austenite effect of nitrogen is 60 times that of manganese, and it can replace part of manganese. When nitrogen and manganese are combined, manganese can significantly increase the solubility of nitrogen in steel. Therefore, how to optimize the process to increase the nitrogen content of high manganese steel to improve material properties has become a new research direction. Summary of the invention

[0004] The invention provides a process for preparing nitrogen-containing high manganese steel by blowing nitrogen in a medium frequency furnace, so as to solve the problems that the existing air-permeable bricks have poor mechanical properties, air permeability and slag erosion resistance and cannot well meet the process requirements for preparing nitrogen-containing high manganese steel by blowing nitrogen in a medium frequency furnace.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A process for preparing nitrogen-containing high manganese steel by blowing nitrogen in a medium frequency furnace comprises the following steps:

[0007] (1) Knotting the crucible: Install the air-permeable bricks at the bottom of the medium frequency furnace as required, then use the furnace lining material and mold to knot the crucible, dry and sinter;

[0008] (2) Design and manufacture the gas diffuser according to the volume of the medium frequency furnace;

[0009] (3) Install the gas diffuser at the bottom center of the medium frequency furnace and connect it to the nitrogen blowing system;

[0010] (4) Prepare materials: weigh the raw materials for smelting nitrogen-containing high manganese steel according to the chemical composition requirements of nitrogen-containing high manganese steel and set aside;

[0011] (5) Charge smelting: The prepared raw materials are gradually put into the medium frequency furnace for smelting. During the smelting process, nitrogen is blown and the surface of the high manganese steel liquid is covered with slag-making materials until the charge is melted and clear. Samples are taken to analyze the composition in the furnace;

[0012] The slag-making material comprises the following raw materials: quicklime powder, activated clay powder, palygorskite powder, talcum powder, fluorite powder, montmorillonite powder, sepiolite powder, barium aluminate powder, a binder, and water;

[0013] (6) Adjust chemical composition: Calculate and add adjustment materials according to the sampling analysis results until all the materials are melted;

[0014] (7) Furnace calming: After the high manganese steel liquid in the furnace reaches the required temperature, the power is turned off to calm the furnace, and nitrogen is continued to be blown to make the high manganese steel liquid uniform in temperature and quality, so that impurities and gases fully float up and combine with the slag-making materials on the liquid surface;

[0015] (8) Temperature controlled steelmaking: The temperature is controlled, and high manganese steel liquid is poured and quenched to produce nitrogen-containing high manganese steel.

[0016] Furthermore, the treatment of blowing nitrogen during the smelting process in step (5) and covering the surface of the high manganese steel liquid with slag-forming materials includes the following steps: when the charge is melted to form a molten pool, the flow regulator is opened to start blowing nitrogen, and the nitrogen participates in the smelting process of the high manganese steel liquid through the air-permeable bricks, and the slag-forming materials are covered on the surface of the high manganese steel liquid during the smelting process.

[0017] Furthermore, when the charge melts to form a molten pool, that is, when the high manganese molten steel covers the furnace bottom by more than 30 cm, the flow regulator is opened to start blowing nitrogen.

[0018] Furthermore, the slag-making material includes the following raw materials in parts by weight: 76 parts of quicklime powder, 48 parts of activated clay powder, 20 parts of palygorskite powder, 11 parts of talc powder, 13 parts of fluorite powder, 8 parts of montmorillonite powder, 4 parts of sepiolite powder, 3 parts of barium aluminate powder, 5 parts of epoxy resin, and 157 parts of water.

[0019] Furthermore, the added amount of the slag-forming material is 0.76-0.82 kg / ton of steel.

[0020] Furthermore, the nitrogen-containing high manganese steel in step (8) is analyzed by spectral analysis (by mass percentage) to obtain the following components: 0.9-2.0% C, 0.3-1.5% Si, 8-25% Mn, <0.05% P, <0.05% S, <3.0% Cr, <1.0% Mo, <1.0% Ni, <1.0% Cu, 0.05-0.15% N, <0.001% O, <0.001% H, the content of other trace elements is <1.0%, and the balance is Fe.

[0021] Furthermore, the nitrogen-containing high manganese steel, through spectral analysis (by mass percentage), obtains the following components: 1.35% C, 0.85% Si, 18.34% Mn, 0.047% P, 0.039% S, 1.28% Cr, 0.75% Mo, 0.81% Ni, 0.92% Cu, 0.12% N, 0.00075% O, 0.00034% H, the content of other trace elements is 0.87%, and the balance is Fe.

[0022] Technical principles and beneficial effects of the present invention:

[0023] (1) The present invention can ensure the stability of the nitrogen content in the high manganese steel solution by selecting appropriate processes and tools for blowing nitrogen under normal atmospheric conditions, thereby ensuring the stability of the performance of the nitrogen-containing high manganese steel material.

[0024] (2) The mechanical properties, air permeability and slag erosion resistance of the air-permeable bricks prepared by the present invention are superior to those of the air-permeable bricks prepared by the prior art, and can meet the process requirements for preparing nitrogen-containing high manganese steel by blowing nitrogen in a medium frequency furnace.

[0025] (3) In the present invention, adding fluorite powder in the preparation of slag-making materials can increase the fluidity of the slag-making materials. Fluorite powder contains CaF 2 , montmorillonite powder contains SiO 2 , and SiO 2 With CaF 2 The reaction can achieve the effect of dehydrogenation, effectively reducing the hydrogen content in high manganese steel liquid; sepiolite powder is a fibrous hydrous magnesium silicate, which absorbs water and becomes soft when it meets water; it is non-toxic, odorless, asbestos-free, and free of radioactive elements, and has the largest specific surface area among non-metallic minerals (up to 900m 2 / g) and unique pore structure, it is recognized as the clay mineral with the strongest adsorption capacity. Due to its large porosity and specific surface area, strong adsorption capacity, it is conducive to adsorbing impurities such as hydrogen and oxygen in high manganese steel water; barium aluminate added to the prepared slag-making material is conducive to removing impurities such as oxygen in high manganese steel water and reducing the content of impurities in high manganese steel water. Therefore, under the cooperation of fluorite powder, montmorillonite powder, sepiolite powder and barium aluminate, the oxygen and hydrogen content in nitrogen-containing high manganese steel can be effectively reduced, and the elongation of nitrogen-containing high manganese steel can be synergistically improved.

[0026] (4) On the one hand, nitrogen is an inert gas. Nitrogen is blown into high manganese molten steel through the air-permeable bricks of the present invention. The air-permeable bricks make the nitrogen bubbles small and fully and evenly dispersed. When nitrogen passes through the high manganese molten steel, [H], [O], etc. dissolved in the high manganese molten steel will automatically diffuse into the nitrogen bubbles and rise with the bubbles and be removed from the high manganese molten steel. Non-metallic inclusions adhere to the nitrogen, and the combination thereof floats to the surface of the high manganese molten steel and then adheres to the slag-making material, thereby purifying the high manganese molten steel, reducing the oxygen and hydrogen content, and improving the comprehensive mechanical properties of nitrogen-containing high manganese steel. On the other hand, nitrogen has a certain solubility in the matrix structure and is stronger than manganese in the formation of the austenite matrix. The austenite effect of nitrogen is 60 times that of manganese, and it can replace part of manganese. Nitrogen and manganese are combined, and manganese can significantly increase the solubility of nitrogen in steel, thereby reducing production costs.

[0027] (5) The present invention improves the uniformity of the as-cast structure, increases the austenite content of the as-cast high manganese steel, and reduces the probability of cracking of the high manganese steel in the as-cast state.

[0028] (6) The nitrogen-containing high manganese steel prepared by the present invention has an elongation of 24.9%, an oxygen content of 7.5 ppm, and a hydrogen content of 3.4 ppm. It can be seen that the oxygen content and the hydrogen content are both below 10 ppm, indicating that the nitrogen-containing high manganese steel prepared by the process of the present invention has extremely high purity and excellent performance, and can meet the requirements of being used in the production of wear-resistant parts of large cone and jaw crushers, as well as other parts that are subjected to large impact loads and require wear resistance, which is of great significance. DETAILED DESCRIPTION

[0029] In order to facilitate a better understanding of the present invention, the following examples are used to illustrate the present invention. These examples belong to the protection scope of the present invention, but do not limit the protection scope of the present invention.

[0030] Example 1

[0031] A process for preparing nitrogen-containing high manganese steel by blowing nitrogen in a medium frequency furnace comprises the following steps:

[0032] (1) Knotting the crucible: Install the air-permeable bricks at the bottom of the medium frequency furnace as required, then use the furnace lining material and mold to knot the crucible, dry and sinter;

[0033] The air-permeable brick comprises the following raw materials, in parts by weight: 75 parts of pure magnesium aluminum spinel ultra-large microporous particles, 46 parts of forsterite sand, 30 parts of fused magnesia sand, 23 parts of chromium oxide micropowder, 7 parts of potassium hexametaphosphate, 5 parts of nano sodium silicate, 3 parts of bamboo fiber, 6 parts of potassium permanganate, 2 parts of explosion-proof fiber, 0.3 parts of rosin soap, and 1 part of polycarboxylic acid water reducer;

[0034] The Al content of the pure magnesium aluminum spinel ultra-large microporous particles is 2 O 3The content is 73.2wt%, and the average particle size is 2.4mm;

[0035] The method for preparing the air-permeable brick comprises the following steps:

[0036] S1. Ingredients: prepare the raw materials according to the components and weight proportions;

[0037] S2, premixing: placing the raw materials prepared in step S1 into a premixing furnace, stirring at a speed of 300 r / min for 20 min to obtain a premix;

[0038] S3, vibration molding: the premix prepared in step S2 is transferred into a mold, and molded by a hydraulic press at 120 MPa to obtain a green air brick;

[0039] S4, curing with mold: placing the green air brick obtained in step S3 at 38°C and curing with mold for 7 hours;

[0040] S5, demoulding: after the mold curing in step S4 is completed, demoulding is performed at room temperature to obtain a breathable brick body;

[0041] S6, curing: curing the air-permeable brick body obtained in step S5 at 28° C. for 25 hours;

[0042] S7, baking: baking the air-permeable brick body after the curing in step S6 at 500° C. for 4 days, and obtaining the air-permeable brick after the baking;

[0043] (2) Design and manufacture the gas diffuser according to the volume of the medium frequency furnace;

[0044] (3) Install the gas diffuser at the bottom center of the medium frequency furnace and connect it to the nitrogen blowing system;

[0045] (4) Prepare materials: weigh the raw materials for smelting nitrogen-containing high manganese steel according to the chemical composition requirements of nitrogen-containing high manganese steel and set aside;

[0046] (5) Charge smelting: The prepared raw materials are gradually put into the medium frequency furnace for smelting. When the charge is melted to form a molten pool, that is, when the high manganese molten steel covers the furnace bottom by 28.6 cm, the flow regulator is opened to blow nitrogen. The nitrogen participates in the smelting process of the high manganese molten steel through the air-permeable bricks. During the smelting process, the slag-making material is covered on the surface of the high manganese molten steel. The addition amount is 0.76 kg / ton of steel until the charge is melted. Samples are taken to analyze the composition in the furnace;

[0047] The slag-making material, in parts by weight, includes the following raw materials: 76 parts of quicklime powder, 48 parts of activated clay powder, 20 parts of palygorskite powder, 11 parts of talc powder, 13 parts of fluorite powder, 8 parts of montmorillonite powder, 4 parts of sepiolite powder, 3 parts of barium aluminate powder, 5 parts of epoxy resin, and 157 parts of water;

[0048] The quality index of the quicklime powder raw material is: CaO: 95.36%; particle size is 700 mesh;

[0049] The quality index of the activated clay powder raw material is: SiO 2 :58.14%;Al 2 O 3 : 16.79%; MgO: 3.26%; particle size is 900 mesh;

[0050] The quality index of the palygorskite powder raw material is: SiO 2 : 53.54%; MgO: 22.56%; particle size is 900 mesh;

[0051] The quality index of the talcum powder raw material is: SiO 2 : 58.79%; MgO: 25.67%; particle size is 1000 mesh;

[0052] The quality index of the fluorite powder raw material is: CaF 2 : 80.12%; particle size is 800 mesh;

[0053] The quality index of the montmorillonite powder raw material is: SiO 2 :56.97%;Al 2 O 3 : 14.28%; particle size is 800 mesh;

[0054] The particle size of the sepiolite powder is 900 mesh;

[0055] The particle size of the barium aluminate powder is 800 mesh;

[0056] The method for preparing the slag-making material comprises the following steps:

[0057] 1) crushing quicklime, activated clay, palygorskite, talc, fluorite, montmorillonite, sepiolite, and barium aluminate respectively to obtain quicklime powder, activated clay powder, palygorskite powder, talc powder, fluorite powder, montmorillonite powder, sepiolite powder, and barium aluminate powder;

[0058] 2) Add quicklime powder, activated clay powder, palygorskite powder, talcum powder, fluorite powder, montmorillonite powder, sepiolite powder, barium aluminate powder, epoxy resin and water into a mixer according to weight proportions, and stir at a temperature of 43° C. and a speed of 300 r / min for 0.9 h to obtain a mixture;

[0059] 3) adding the mixture obtained in step 2) into a mold, and forming particles with a particle size of 0.8 cm after vacuum filtration;

[0060] 4) feeding the particles obtained in step 3) into an oven and drying them at 80° C. for 10 h to obtain a slag-making material;

[0061] (6) Adjust chemical composition: Calculate and add adjustment materials according to the sampling analysis results until all the materials are melted;

[0062] (7) Furnace calming: After the high manganese steel liquid in the furnace reaches the required temperature, the power is turned off to calm the furnace, and nitrogen is continued to be blown to make the high manganese steel liquid uniform in temperature and quality, so that impurities and gases fully float up and combine with the slag-making materials on the liquid surface;

[0063] (8) Temperature-controlled steelmaking: The temperature is controlled, and high manganese steel is poured and quenched to obtain nitrogen-containing high manganese steel. Spectral analysis (by mass percentage) shows that the steel contains the following components: 1.35% C, 0.85% Si, 18.34% Mn, 0.047% P, 0.039% S, 1.28% Cr, 0.75% Mo, 0.81% Ni, 0.92% Cu, 0.12% N, 0.00075% O, 0.00034% H, and the content of other trace elements is 0.87%, with the balance being Fe.

[0064] Example 2

[0065] A process for preparing nitrogen-containing high manganese steel by blowing nitrogen in a medium frequency furnace comprises the following steps:

[0066] (1) Knotting the crucible: Install the air-permeable bricks at the bottom of the medium frequency furnace as required, then use the furnace lining material and the mold to knot the crucible, dry and sinter, wherein the air-permeable bricks and the preparation method are the same as those in Example 1;

[0067] (2) Design and manufacture the gas diffuser according to the volume of the medium frequency furnace;

[0068] (3) Install the gas diffuser at the bottom center of the medium frequency furnace and connect it to the nitrogen blowing system;

[0069] (4) Prepare materials: weigh the raw materials for smelting nitrogen-containing high manganese steel according to the chemical composition requirements of nitrogen-containing high manganese steel and set aside;

[0070] (5) Charge smelting: The prepared raw materials are gradually put into the medium frequency furnace for smelting. When the charge is melted to form a molten pool, that is, when the high manganese molten steel covers the furnace bottom by 28.9 cm, the flow regulator is opened to blow nitrogen. The nitrogen participates in the smelting process of the high manganese molten steel through the air-permeable bricks. During the smelting process, the slag-forming material is covered on the surface of the high manganese molten steel. The addition amount is 0.82 kg / ton of steel until the charge is melted. Samples are taken to analyze the components in the furnace. The slag-forming material and its preparation method are the same as those in Example 1.

[0071] (6) Adjust chemical composition: Calculate and add adjustment materials according to the sampling analysis results until all the materials are melted;

[0072] (7) Furnace calming: After the high manganese steel liquid in the furnace reaches the required temperature, the power is turned off to calm the furnace, and nitrogen is continued to be blown to make the high manganese steel liquid uniform in temperature and quality, so that impurities and gases fully float up and combine with the slag-making materials on the liquid surface;

[0073] (8) Temperature-controlled steelmaking: The temperature is controlled, and high manganese steel is poured and quenched to obtain nitrogen-containing high manganese steel. Spectral analysis (by mass percentage) shows that the steel contains the following components: 1.12% C, 0.42% Si, 13.24% Mn, 0.039% P, 0.041% S, 2.63% Cr, 0.82% Mo, 0.46% Ni, 0.71% Cu, 0.09% N, 0.00093% O, 0.00048% H, and the content of other trace elements is 0.84%, with the balance being Fe.

[0074] Example 3

[0075] A process for preparing nitrogen-containing high manganese steel by blowing nitrogen in a medium frequency furnace comprises the following steps:

[0076] (1) Knotting the crucible: Install the air-permeable bricks at the bottom of the medium frequency furnace as required, then use the furnace lining material and the mold to knot the crucible, dry and sinter, wherein the air-permeable bricks and the preparation method are the same as those in Example 1;

[0077] (2) Design and manufacture the gas diffuser according to the volume of the medium frequency furnace;

[0078] (3) Install the gas diffuser at the bottom center of the medium frequency furnace and connect it to the nitrogen blowing system;

[0079] (4) Prepare materials: weigh the raw materials for smelting nitrogen-containing high manganese steel according to the chemical composition requirements of nitrogen-containing high manganese steel and set aside;

[0080] (5) Charge smelting: The prepared raw materials are gradually put into the medium frequency furnace for smelting. When the charge is melted to form a molten pool, that is, when the high manganese molten steel covers the furnace bottom by 29.1 cm, the flow regulator is opened to blow nitrogen. The nitrogen participates in the smelting process of the high manganese molten steel through the air-permeable bricks. During the smelting process, the slag-forming material is covered on the surface of the high manganese molten steel. The addition amount is 0.8 kg / ton of steel until the charge is melted. Samples are taken to analyze the components in the furnace. The slag-forming material and its preparation method are the same as those in Example 1.

[0081] (6) Adjust chemical composition: Calculate and add adjustment materials according to the sampling analysis results until all the materials are melted;

[0082] (7) Furnace calming: After the high manganese steel liquid in the furnace reaches the required temperature, the power is turned off to calm the furnace, and nitrogen is continued to be blown to make the high manganese steel liquid uniform in temperature and quality, so that impurities and gases fully float up and combine with the slag-making materials on the liquid surface;

[0083] (8) Temperature-controlled steelmaking: The temperature is controlled, and high manganese steel is poured and quenched to obtain nitrogen-containing high manganese steel. Spectral analysis (by mass percentage) shows that the steel contains the following components: 1.76% C, 0.94% Si, 24.87% Mn, 0.028% P, 0.036% S, 2.18% Cr, 0.93% Mo, 0.25% Ni, 0.51% Cu, 0.08% N, 0.00086% O, 0.00041% H, and the content of other trace elements is 0.69%, with the balance being Fe.

[0084] Comparative Example 1

[0085] The breathable bricks were prepared by the method of Example 2 of the Chinese patent document "Preparation process of improved breathable bricks for ladle for producing high-purity high-manganese steel (patent number: ZL201811628852.X)".

[0086] The air-permeable bricks prepared in Example 1 and the air-permeable bricks in Comparative Example 1 were tested for mechanical properties, air permeability, and slag erosion resistance. The specific testing methods are as follows:

[0087] 1. Mechanical properties: According to YB / T5201, the compressive strength of the specimens at room temperature was tested after heat treatment at 110℃ for 24h and 1550℃ for 3h.

[0088] 2. Air permeability: According to YB / T5200, the apparent porosity of the specimens was tested after heat treatment at 110℃ for 24h and 1550℃ for 3h.

[0089] 3. Resistance to slag erosion: Load the samples into 1#-10# crucibles respectively, and then take the LF furnace final slag with a particle size of <0.5mm and load it into 1#-10# crucibles. The slag loading amount of each crucible is 120g. Heat it to 1600℃ in an electric furnace and keep it for 4h, then cool it naturally to room temperature. Then take out the sample and cut it into two halves symmetrically, and measure the erosion depth. The smaller the value, the better the resistance to slag erosion.

[0090] The above test results are shown in the following table:

[0091]

[0092]

[0093] It can be seen from the above table that: from the data of Example 1 and Comparative Example 1 (prior art), it can be seen that the mechanical properties, air permeability and slag erosion resistance of the breathable bricks prepared in Example 1 are better than the mechanical properties, air permeability and slag erosion resistance of the breathable bricks prepared in the prior art, and can meet the process requirements of preparing nitrogen-containing high manganese steel by blowing nitrogen in a medium frequency furnace.

[0094] Comparative Example 2

[0095] The preparation process of the nitrogen-containing high manganese steel is basically the same as that of Example 1, except that the raw materials for preparing the breathable bricks lack nano sodium silicate, bamboo fiber, and potassium permanganate.

[0096] Comparative Example 3

[0097] The preparation process of the nitrogen-containing high manganese steel is basically the same as that of Comparative Example 1, except that nano sodium silicate is added to the raw materials for preparing the breathable bricks.

[0098] Comparative Example 4

[0099] The preparation process of the nitrogen-containing high manganese steel is basically the same as that of Comparative Example 1, except that bamboo fiber is added to the raw materials for preparing the breathable bricks.

[0100] Comparative Example 5

[0101] The preparation process of the nitrogen-containing high manganese steel is basically the same as that of Comparative Example 1, except that potassium permanganate is added to the raw materials for preparing the breathable bricks.

[0102] The elongation and oxygen and hydrogen contents of the nitrogen-containing high manganese steels prepared in Example 1 and Comparative Examples 2-5 were tested, and the results were as follows:

[0103]

[0104] Note: Oxygen and hydrogen contents are detected by spectral analysis; “-” means no inspection.

[0105] (1) The elongation of the nitrogen-containing high manganese steel prepared by Example 1 is 24.9%, the oxygen content is 7.5 ppm, and the hydrogen content is 3.4 ppm. It can be seen that the oxygen content and the hydrogen content are both below 10 ppm, indicating that the nitrogen-containing high manganese steel prepared by the process of the present invention has extremely high purity and excellent performance, which can meet the application requirements.

[0106] (2) From the elongation data of Example 1 and Comparative Examples 2-5, it can be seen that nano sodium silicate, bamboo fiber, and potassium permanganate play a synergistic role in the preparation of nitrogen-containing high manganese steel, and synergistically improve the elongation of nitrogen-containing high manganese steel. This is because: after the introduction of nano sodium silicate into the air-permeable brick, uniformly distributed micropores are formed inside the air-permeable brick, which can prevent the diffusion of cracks in the air-permeable brick; bamboo fiber releases gas during the preparation process, which increases the porosity of the air-permeable brick, thereby improving the apparent porosity of the air-permeable brick; potassium permanganate is added during the preparation of the air-permeable brick, and the added potassium permanganate can decompose and produce oxygen during the preparation, making the interior of the blank rich in pores, thereby improving the apparent porosity of the air-permeable brick. Therefore, bamboo fiber, nano sodium silicate and potassium permanganate cooperate with each other in the preparation of breathable bricks to play a synergistic role, which can synergistically improve the apparent porosity of breathable bricks. Since the apparent porosity of breathable bricks is extremely high, the nitrogen blowing is sufficient and uniform, which effectively reduces the oxygen and hydrogen content in the high manganese steel water. On the basis of not increasing the alloying elements, the elongation of nitrogen-containing high manganese steel is synergistically improved.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A process for preparing nitrogen-containing high manganese steel by blowing nitrogen in a medium frequency furnace, characterized in that: The following steps are involved: (1) Knotting the crucible: Install the air-permeable bricks at the bottom of the medium frequency furnace as required, then use the furnace lining material and mold to knot the crucible, dry and sinter; (2) Design and manufacture the gas diffuser according to the volume of the medium frequency furnace; (3) Install the gas diffuser at the bottom center of the medium frequency furnace and connect it to the nitrogen blowing system; (4) Prepare materials: weigh the raw materials for smelting nitrogen-containing high manganese steel according to the chemical composition requirements of nitrogen-containing high manganese steel and set them aside; (5) Charge smelting: The prepared raw materials are gradually put into the medium frequency furnace for smelting. During the smelting process, nitrogen is blown and the surface of the high manganese steel liquid is covered with slag-making materials until the charge is melted and clear. Samples are taken to analyze the composition in the furnace; The treatment of blowing nitrogen and covering the surface of high manganese molten steel with slag-forming materials during the smelting process includes the following steps: when the charge is melted to form a molten pool, the flow regulator is opened to start blowing nitrogen, and the nitrogen participates in the smelting process of high manganese molten steel through the air-permeable bricks, and the slag-forming materials are covered on the surface of the high manganese molten steel during the smelting process; The slag-making material, in parts by weight, includes the following raw materials: 76 parts of quicklime powder, 48 parts of activated clay powder, 20 parts of palygorskite powder, 11 parts of talc powder, 13 parts of fluorite powder, 8 parts of montmorillonite powder, 4 parts of sepiolite powder, 3 parts of barium aluminate powder, 5 parts of epoxy resin, and 157 parts of water; The amount of slag-making material added is 0.76-0.82 kg / ton of steel; (6) Adjust chemical composition: Calculate and add adjustment materials according to the sampling analysis results until all materials are melted; (7) Furnace calming: After the high manganese steel liquid in the furnace reaches the required temperature, the power is turned off for calming, and nitrogen is continued to be blown to make the high manganese steel liquid uniform in temperature and quality, so that impurities and gases fully float up and combine with the slag-making materials on the liquid surface; (8) Temperature controlled steelmaking: Control the temperature, pour and quench the high manganese steel liquid to obtain nitrogen-containing high manganese steel.

2. The process for preparing nitrogen-containing high manganese steel by blowing nitrogen in a medium frequency furnace according to claim 1, characterized in that: When the charge melts to form a molten pool, that is, when the high manganese steel liquid covers the furnace bottom by more than 30 cm, start opening the flow regulator to blow nitrogen.

3. The process for preparing nitrogen-containing high manganese steel by blowing nitrogen in a medium frequency furnace according to claim 1, characterized in that: The nitrogen-containing high manganese steel in step (8) comprises the following components, measured by mass percentage by spectral analysis: 0.9-2.0% C, 0.3-1.5% Si, 8-25% Mn, <0.05% P, <0.05% S, <3.0% Cr, <1.0% Mo, <1.0% Ni, <1.0% Cu, 0.05-0.15% N, <0.001% O, <0.001% H, the content of other trace elements is <1.0%, and the balance is Fe.

4. The process for preparing nitrogen-containing high manganese steel by blowing nitrogen in a medium frequency furnace according to claim 3, characterized in that: The nitrogen-containing high manganese steel is analyzed by spectral analysis and, in terms of mass percentage, comprises the following components: 1.35% C, 0.85% Si, 18.34% Mn, 0.047% P, 0.039% S, 1.28% Cr, 0.75% Mo, 0.81% Ni, 0.92% Cu, 0.12% N, 0.00075% O, 0.00034% H, the content of other trace elements is 0.87%, and the balance is Fe.

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