Process method for alloying smelting of ultralow-temperature high-manganese steel

Abstract

The invention discloses an ultralow-temperature high manganese steel alloying smelting process method which comprises the steps of molten iron pretreatment, converter smelting, LF refining and continuous casting, and after converter tapping, alloying smelting of high manganese steel with the mass percentage of 20%-30% is completed in an LF; multi-batch alloying smelting at gradient temperature is cooperated with a CaO-BaO-Li2O-Al2O3-CaF2-MgO-Ce2O3-based self-sealing slag system for inhibiting volatilization of Mn element in molten steel and slag / molten steel interface reaction, and CO2-Ar mixed gas is sprayed in through a steel ladle bottom blowing air brick in a pulse injection form, so that high-yield alloying smelting of ultralow-temperature high-manganese steel is realized; and the whole process of the method is completed in an LF furnace, the molten steel is not subjected to RH / VD vacuum treatment subsequently, and the Mn element volatilization risk caused by the vacuum environment is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel metallurgy, and more particularly to a process method for alloying smelting of ultra-low-temperature high-manganese steel. BACKGROUND

[0002] As the best candidate material for LNG tank preparation, the efficient and low-cost smelting process of ultra-low-temperature high-manganese steel (22% to 30% of the mass percentage of Mn element) has been a research hotspot. However, there are two technical bottlenecks in the smelting process: first, the serious temperature drop problem of manganese element alloying, the melting heat absorption of manganese iron alloy (FeMn) is as high as 300-400 kJ / kg, and the serious temperature drop of molten steel caused by the traditional experience of adding Mn alloy in batches will significantly reduce the smelting efficiency; second, the uncontrollable volatilization of manganese element in high-temperature molten steel, the saturation vapor pressure of Mn element at high temperature is relatively high, and it is relatively easy to volatilize, resulting in low recovery rate of Mn element alloying, and the Mn vapor is toxic, not only causing certain pollution to the environment, but also affecting the health of the operators. For a long time, the design of metallurgical equipment and the optimization of metallurgical process are the main direction to break through the technical bottleneck of high-manganese steel alloying, such as POSCO in South Korea, which uses the PosLM (POSCO Liquid Manganese) equipment to produce high-manganese steel by using molten manganese iron alloy (FeMn) for the first time, which shortens the smelting time of high-manganese steel by half; and the method for smelting high-manganese steel in a converter (CN202310548812.9) of China Shougang, which adds carbon balls and high-carbon manganese iron in stages according to the oxygen blowing amount in the converter smelting process, reduces the investment of alloy heating furnace and other equipment through process optimization, and reduces the production cost of high-manganese steel. However, starting from the balance point of production efficiency and production cost of high-manganese steel billet, there are still many places that need to be considered comprehensively, such as the capital investment of new equipment, the energy consumption of high-manganese steel smelting, and the erosion of the refractory material in the converter. The present application mainly optimizes the metallurgical process, designs a multi-batch alloying smelting process with gradient temperature control of molten steel in the LF furnace, reduces energy consumption, and solves the temperature drop problem of Mn element alloying; at the same time, a CaO-BaO-Li2O-Al2O3-CaF2-MgO-Ce2O3-based self-sealing slag system is designed to reduce the volatilization of Mn element in molten steel; and combined with the optimization of bottom blowing process, the high-recovery alloying smelting of ultra-low-temperature high-manganese steel is realized. SUMMARY

[0003] The purpose of this invention is to overcome the aforementioned defects in the existing technology and provide a process for alloying high-manganese steel at ultra-low temperature. The smelting and preparation process includes hot metal pretreatment, converter smelting, LF refining, and continuous casting. After tapping from the converter, alloying smelting of high-manganese steel with a mass percentage of 20%-30% is completed in the LF furnace. Through gradient temperature multi-batch alloying smelting, in conjunction with a CaO-BaO-Li2O-Al2O3-CaF2-MgO-Ce2O3-based self-sealing slag system that inhibits the volatilization of Mn element in the molten steel and the slag / molten steel interface reaction, and combined with CO2-Ar mixed gas injected into the ladle through the bottom blowing permeable brick in the form of pulse injection, high-yield alloying smelting of ultra-low temperature high-manganese steel is achieved. Moreover, this method is completed entirely in the LF furnace, and the molten steel does not subsequently undergo RH / VD vacuum treatment, avoiding the risk of Mn element volatilization caused by the vacuum environment.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows:

[0005] A process for alloying high-manganese steel at ultra-low temperatures includes hot metal pretreatment, converter smelting, LF refining, and continuous casting.

[0006] In the LF refining process, the molten steel after converter smelting is transferred to the LF furnace at an inlet temperature of 1600-1620°C for LF refining treatment; wherein the LF refining treatment includes a first stage, a second stage, a third stage and a fourth stage.

[0007] In the first stage, after the molten steel is smelted in the converter, pre-melted slag balls and aluminum particles are added into the LF furnace. The oxygen content in the molten steel is controlled to be ≤20ppm. Then, preheated ferromanganese with a mass percentage of 20% to 30% is added. After the preheated ferromanganese is added for 1.5 to 2 minutes, the temperature of the molten steel is measured. When the detected temperature of the molten steel is lower than the set first target temperature T1, electrode heating is used to compensate for the temperature. The electrode heating power P is determined according to formula (1). The molten steel is heated to the first target temperature T1 by the electrode heating power P. The target characteristic depth of electrode heating is 1.1 to 1.2 times the actual molten pool depth. The feeding rate is 0.6 to 2t / min. Argon gas is blown from the bottom to control the final Al mass percentage to be ≤0.05%. The pre-melted slag balls are CaO-BaO-Li2O-Al2O3-CaF2-MgO-Ce2O3 slag system.

[0008] In the second stage, after the molten steel in the converter smelting process is fed and heated by electrodes in the first stage, aluminum particles are added after the temperature is replenished to T1. The oxygen content in the molten steel is controlled to be ≤20ppm. Then, preheated ferromanganese with a mass percentage of 50% to 70% is added. After the preheated ferromanganese is added for 2 to 2.5 minutes, the temperature of the molten steel is measured. When the detected temperature of the molten steel is lower than the set second target temperature T2, electrode heating is used to replenish the temperature. The electrode heating power P is determined according to formula (1). The molten steel is heated to the second target temperature T2 by the electrode heating power P. The target characteristic depth of electrode heating is the actual depth of the molten pool. The feeding rate is 1 to 3 t / min. Argon gas is blown from the bottom to control the final Al mass percentage to be ≤0.05%.

[0009] In the third stage, after the molten steel in the converter smelting process is fed and heated by electrodes in the second stage, and then heated to T2, aluminum particles are added to control the oxygen content in the molten steel to be ≤20ppm and the Al mass percentage to be 0.06-0.08%. Then, preheated ferromanganese with a mass percentage of 10%-20% is added. After the preheated ferromanganese is added for 1.5-2 minutes, the temperature of the molten steel is measured. When the detected temperature of the molten steel is lower than the set third target temperature T3, electrode heating is used to supplement the temperature. The electrode heating power P is determined according to formula (1), and the molten steel is heated to the third target temperature T3 by the electrode heating power P. The target characteristic depth of electrode heating is 0.6-0.8 times the actual molten pool depth, and the feeding rate is 0.3-1t / min. After adding the aluminum particles, CO2-Ar mixed gas is injected into the ladle through the bottom blower permeable brick in the form of pulse jet. The final Al mass percentage is controlled to be ≤0.07%.

[0010] In the fourth stage, after the molten steel in the converter is smelted, it is fed and heated by electrodes in the third stage. After the temperature is replenished to T3, the blowing gas is stopped, the power is cut off, and it is left to stand for 5 to 30 minutes. The oxygen content at the end point is controlled to be ≤15ppm and Mn is 20% to 30%.

[0011] Electrode heating power P = 150 × (T) 目标温度 -T 钢液温度 ) 1.2 ×e (-0.15*d) +20×V (1);

[0012] Where V is the feeding rate (t / min); d is the target characteristic depth of electrode heating (m), d=k*H, k is the depth coefficient, k=1.1~1.2 in the first stage, k=1.0 in the second stage, and k=0.6~0.8 in the third stage; H is the molten pool depth.

[0013] Optionally, in the converter smelting process, aluminum particles are added during the tapping process for strong deoxidation to control the final oxygen content in the molten steel to ≤50ppm.

[0014] Optionally, in the first stage, the flow rate of bottom-blown argon is 0.6–1.0 Nm³. 3 / min.

[0015] Optionally, in the second stage, the flow rate of bottom-blown argon is 1.0–1.5 Nm³. 3 / min.

[0016] Optionally, in the third stage, the CO2 volume percentage in the CO2-Ar mixture is 25-35%, and the bottom-blowing flow rate of the CO2-Ar mixture is 0.3-1.0 Nm³. 3 / min, injection pressure 0.1~0.2MPa, pulse frequency 5~20Hz, CO2 purity ≥99.9%.

[0017] Optionally, the temperature of the preheated ferromanganese is 400–600°C.

[0018] Optionally, the pre-melted slag balls comprise the following components by mass percentage: 35-40% CaO, 12-25% BaO, 2-4% Li2O, 15-20% Al2O3, 8-15% CaF2, 3-8% MgO, and 0.5-1.0% Ce2O3.

[0019] Optionally, the diameter of the pre-melted slag ball is 5 to 20 mm.

[0020] Optionally, the amount of the pre-melted slag balls used is 8-15 kg / t steel.

[0021] Optionally, the first target temperature T1 is 1580℃~1600℃; the second target temperature T2 is 1530℃~1550℃; and the third target temperature T3 is 1520℃~1530℃.

[0022] The purpose of this invention is to solve the serious temperature drop problem during manganese alloying in ultra-low temperature high-manganese steel smelting and the volatilization problem of manganese in high-temperature molten steel, thereby improving the yield of manganese alloying smelting. Implementing the embodiments of this invention will have the following beneficial effects:

[0023] (1) The method of the present invention, through the technical route of gradient thermal compensation, clarifies the gradient temperature alloying stage and the steel molten temperature replenishment formula in LF, and performs multi-stage batch replenishment melting to accurately compensate for the temperature drop caused by the melting of Mn element and avoid heat loss. Moreover, the molten steel does not undergo RH / VD vacuum treatment afterward, avoiding the risk of Mn element volatilization caused by the vacuum environment.

[0024] (2) The method of the present invention reduces the diffusion and volatilization of Mn element by combining a self-sealing slag system with segmented gas control and multiple process combinations, thereby improving the yield of Mn element and reducing environmental pollution and harm to workers' health.

[0025] (3) The method of the present invention shortens the smelting cycle of high manganese steel, reduces production costs, has great cost advantages, improves the alloying efficiency of manganese in ultra-low temperature high manganese steel, reduces the volatilization of manganese during smelting, and improves the alloying smelting yield of manganese. Attached Figure Description

[0026] Figure 1 This is a flow chart of the process for alloying high-manganese steel at ultra-low temperatures according to the present invention. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way.

[0028] Example 1

[0029] When smelting ultra-low temperature high-manganese steel for LNG, the alloy contains 24% to 26% Mn by mass and 0.45% C by mass. It is smelted using a 120-ton ladle and mainly includes the following steps: hot metal pretreatment, converter smelting, LF refining and continuous casting.

[0030] S1. After the molten iron is pretreated, aluminum particles are added during the converter smelting and tapping process to carry out strong deoxidation and control the final oxygen content in the molten steel to ≤50ppm.

[0031] S2 and LF alloying smelting preparation: Preheat ferromanganese to 500℃ to obtain preheated ferromanganese; Preparation method of pre-melted slag balls: Weigh by mass percentage: CaO 40% + BaO 16% + Li2O 4% + Al2O3 20% + CaF2 15% + MgO 4% + Ce2O3 1%, pre-melt into Φ10mm pre-melted slag balls (melting point 1180℃), dosage 10kg / t steel.

[0032] In S3 and LF refining, the molten steel after converter smelting is transferred to the LF furnace at an inlet temperature of 1610℃ for refining treatment; the LF refining treatment includes the first stage, the second stage, the third stage and the fourth stage.

[0033] In the first stage, after the molten steel from the converter smelting process enters the LF furnace, pre-melted slag balls and aluminum granules are immediately added to control the oxygen content in the molten steel to ≤20ppm. Then, preheated ferromanganese with a mass percentage of 25% is added. Two minutes after the addition of the preheated ferromanganese, the temperature of the molten steel is measured. The measured temperature of the molten steel is 1575℃, which is lower than the set first target temperature of 1580℃. Electrode heating is used to compensate for the temperature. According to formula (1), the electrode heating power P = 858KW is determined. The electrode heating power P is used to heat the molten steel to the first target temperature. The target characteristic depth of electrode heating is 1.44m, and the feeding rate is 1.2t / min. Considering the electrode heating power and heat consumption, it takes about 35s to 45s to increase the temperature by 1℃. Electrode heating is turned on for 5 minutes, and the temperature is measured. At this time, the temperature is 1582℃. The flow rate of bottom-blown argon is 0.8Nm. 3 / min, with the control endpoint of Al mass percentage being 0.05%.

[0034] In the second stage, after the molten steel was heated to 1582℃ by the first stage of feeding and electrode heating, aluminum particles were added to control the oxygen content in the molten steel to ≤20ppm. Then, preheated ferromanganese with a mass percentage of 60% was added. 2.5 minutes after the addition of the preheated ferromanganese, the temperature of the molten steel was measured. The measured temperature of the molten steel was 1524℃, which was lower than the set second target temperature of 1530℃. Electrode heating was used to supplement the temperature. According to formula (1), the electrode heating power P = 1071KW was determined. The molten steel was heated to the second target temperature with the electrode heating power P. The target characteristic depth of electrode heating was 1.54m, and the feeding rate was 2.5t / min. Considering the electrode heating power and heat consumption, it takes about 40s to 50s to increase the temperature by 1℃. Electrode heating was turned on for 7 minutes, and the temperature was measured. At this time, the temperature was 1533℃. The flow rate of bottom-blown argon was 1.2Nm. 3 / min, with the control endpoint being an Al mass percentage content ≤0.05%.

[0035] In the third stage, after the molten steel is heated to 1533℃ by the second stage of feeding and electrode heating, aluminum particles are added to control the oxygen content in the molten steel to ≤20ppm. Then, 15% preheated ferromanganese is added. 1.5 min after the preheated ferromanganese is added, the temperature of the molten steel is measured. The temperature of the molten steel is 1518℃, which is lower than the set third target temperature of 1520℃. Electrode heating is used to supplement the temperature. According to formula (1), the electrode heating power P = 307KW is determined. The molten steel is heated to the third target temperature with the electrode heating power P. The target characteristic depth of electrode heating is 0.95m and the feeding rate is 0.4t / min. Combining the electrode heating power and heat consumption, it takes about 2 min to 3 min to increase the temperature by 1℃. Electrode heating is turned on for 6 min and the temperature is measured. At this time, the temperature is 1521℃. After adding aluminum granules, a CO2-Ar mixture is injected into the ladle through a bottom-blowing permeable brick in a pulse-jet manner. The CO2 volume percentage in the CO2-Ar mixture is 30%, and the bottom-blowing flow rate of the CO2-Ar mixture is 0.3 Nm³. 3 / min, blowing pressure 0.12MPa, pulse frequency 10Hz, pulse blowing, CO2 purity ≥99.9%, control endpoint Al mass percentage content is 0.07%.

[0036] In the fourth stage, after the molten steel was fed and heated by electrodes in the third stage, the temperature was replenished to 1521℃, the blowing gas was stopped, the power was cut off, and it was left to stand for 10 minutes. The oxygen content at the end point was controlled to be ≤15ppm, the Mn deviation was ±0.15%, the final Mn mass percentage content was 25.2%, and the yield reached 96.8%.

[0037] Electrode heating power P = 150 × (T) 目标温度 -T 钢液温度 ) 1.2 ×e (-0.15*d) +20×V (1);

[0038] Where V is the feeding rate (t / min); d is the target characteristic depth of electrode heating (m), d is the molten pool depth (H) and the objective function of the process, d = k * H, k is the depth coefficient, in the first stage deep heating k = 1.1, in the second stage uniform heating k = 1.0, in the third stage fine-tuning heating in the upper part k = 0.6; H is the molten pool depth.

[0039] Example 2

[0040] When smelting Fe-Mn-C-Cr ultra-low temperature high manganese steel for LNG, the mass percentage of Mn element in this alloy is 24% to 26%, the mass percentage of C element is 0.5%, and the mass percentage of Cr element is 4%. The smelting is carried out using a 120-ton ladle and mainly includes the following steps: hot metal pretreatment, converter smelting, LF refining, and continuous casting.

[0041] S1. In converter smelting, aluminum particles are added during the tapping process for strong deoxidation to control the final oxygen content in the molten steel to ≤50ppm.

[0042] S2 and LF alloying smelting preparation: Preheat ferromanganese to 500℃ to obtain preheated ferromanganese; Preparation method of pre-melted slag balls: Weigh according to the mass ratio: CaO 38% + BaO 18% + Li2O 4% + Al2O3 20% + CaF2 15% + MgO 4% + Ce2O3 1%, pre-melt into Φ10mm pre-melted slag balls, with a dosage of 10kg / t steel.

[0043] In S3 and LF refining, the molten steel after converter smelting is transferred to the LF furnace at an inlet temperature of 1602℃ for refining treatment; the LF refining treatment includes the first stage, the second stage, the third stage and the fourth stage.

[0044] In the first stage, after the molten steel from the converter smelting process enters the LF furnace, pre-melted slag balls and aluminum granules are immediately added to control the oxygen content in the molten steel to ≤20ppm. Then, 20% preheated ferromanganese is added. 1.5 min after the addition of the preheated ferromanganese, the temperature of the molten steel is measured. The measured temperature of the molten steel is 1576℃, which is lower than the set first target temperature of 1580℃. Electrode heating is used to compensate for the temperature. According to formula (1), the electrode heating power P = 656KW is determined. The molten steel is heated to the first target temperature with the electrode heating power P. At this time, the target characteristic depth of electrode heating is 1.41m, and the feeding rate is 0.75t / min. Considering the electrode heating power and heat consumption, it takes about 30s to 40s to increase the temperature by 1℃. The electrode heating is turned on for 5min, and the temperature is measured. At this time, the temperature is 1584℃. The flow rate of bottom-blown argon is 0.8Nm. 3 / min, with the control endpoint of Al mass percentage being 0.05%.

[0045] In the second stage, after the molten steel was heated to 1584℃ by the first stage of feeding and electrode heating, aluminum particles were added to control the oxygen content in the molten steel to ≤20ppm. Then, preheated ferromanganese with a mass percentage of 60% was added. After the preheated ferromanganese was added for 2.5 minutes, the temperature of the molten steel was measured. The measured temperature of the molten steel was 1524℃, which was lower than the set second target temperature of 1530℃. Electrode heating was used to supplement the temperature. According to formula (1), the electrode heating power P = 1065KW was determined. The electrode heating power P was used to heat the molten steel to the second target temperature. The target characteristic depth of electrode heating was 1.52m, and the feeding rate was 2.03t / min. Considering the electrode heating power and heat consumption, it takes about 40s to 60s to increase the temperature by 1℃. The electrode heating was turned on for 8 minutes, and the temperature was measured. At this time, the temperature was 1534℃. The flow rate of bottom blowing argon was 1.2Nm. 3The process speed is controlled at the target Al content (≤0.05%), and the temperature uniformity within the ladle is kept within ±8℃. The processing time for this stage is 8–18 min.

[0046] In the third stage, after the molten steel is heated to 1534℃ by the second stage of feeding and electrode heating, aluminum particles are added to control the oxygen content in the molten steel to ≤20ppm. Then, 20% preheated ferromanganese is added. 1.5min after the preheated ferromanganese is added, the temperature of the molten steel is measured. The measured temperature of the molten steel is 1518℃, which is lower than the set third target temperature of 1520℃. Electrode heating is used to supplement the temperature. According to formula (1), the electrode heating power P = 310KW is determined. The electrode heating power P is used to heat the molten steel to the third target temperature. The target characteristic depth of electrode heating is 0.95m and the feeding rate is 0.56t / min. Combining the electrode heating power and heat consumption, it takes about 3min to 4min to increase the temperature by 1℃. The electrode heating is turned on for 8min and the temperature is measured. At this time, the temperature is 1520℃. After adding aluminum granules, a CO2-Ar mixture is injected into the ladle through a bottom-blowing permeable brick in a pulse-jet manner. The CO2 volume percentage in the CO2-Ar mixture is 30%, and the bottom-blowing flow rate of the CO2-Ar mixture is 0.3 Nm³. 3 The pulse jetting speed is 0.12 MPa, the pulse pressure is 10 Hz, the CO2 purity is ≥99.9%, and the final Al mass percentage is controlled at 0.07%. The processing time for this stage is 18–25 min.

[0047] In the fourth stage, after the molten steel was fed and heated by electrodes in the third stage, the temperature was replenished to 1520℃, the blowing gas was stopped, the power was cut off, and it was left to stand for 10 minutes. The oxygen content at the end point was controlled to be ≤15ppm, the Mn deviation was ±0.15%, the final Mn mass percentage content was 25.4%, and the yield reached 97.2%.

[0048] Electrode heating power P = 150 × (T) 目标温度 -T 钢液温度 ) 1.2 ×e (-0.15*d) +20×V (1);

[0049] Where V is the feeding rate (t / min); d is the target characteristic depth of electrode heating (m), d is the molten pool depth (H) and the objective function of the process, d=k*H, k is the depth coefficient, H is the molten pool depth, in the first stage deep heating k=1.1, in the second stage uniform heating k=1.0, in the third stage fine-tuning heating in the upper part k=0.6.

[0050] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A process for alloying high-manganese steel at ultra-low temperatures, characterized in that, This includes hot metal pretreatment, converter smelting, LF refining, and continuous casting; In the LF refining process, the molten steel after converter smelting is transferred to the LF furnace at an inlet temperature of 1600-1620°C for LF refining treatment; wherein the LF refining treatment includes a first stage, a second stage, a third stage and a fourth stage. In the first stage, after the molten steel is smelted in the converter, pre-melted slag balls and aluminum particles are added into the LF furnace. The oxygen content in the molten steel is controlled to be ≤20ppm. Then, preheated ferromanganese with a mass percentage of 20% to 30% is added. After the preheated ferromanganese is added for 1.5 to 2 minutes, the temperature of the molten steel is measured. When the detected temperature of the molten steel is lower than the set first target temperature T1, electrode heating is used to compensate for the temperature. The electrode heating power P is determined according to formula (1). The molten steel is heated to the first target temperature T1 by the electrode heating power P. The target characteristic depth of electrode heating is 1.1 to 1.2 times the actual molten pool depth. The feeding rate is 0.6 to 2t / min. Argon gas is blown from the bottom to control the final Al mass percentage to be ≤0.05%. The pre-melted slag balls are CaO-BaO-Li2O-Al2O3-CaF2-MgO-Ce2O3 slag system. In the second stage, after the molten steel in the converter smelting process is fed and heated by electrodes in the first stage, aluminum particles are added after the temperature is replenished to T1. The oxygen content in the molten steel is controlled to be ≤20ppm. Then, preheated ferromanganese with a mass percentage of 50% to 70% is added. After the preheated ferromanganese is added for 2 to 2.5 minutes, the temperature of the molten steel is measured. When the detected temperature of the molten steel is lower than the set second target temperature T2, electrode heating is used to replenish the temperature. The electrode heating power P is determined according to formula (1). The molten steel is heated to the second target temperature T2 by the electrode heating power P. The target characteristic depth of electrode heating is the actual depth of the molten pool. The feeding rate is 1 to 3 t / min. Argon gas is blown from the bottom to control the final Al mass percentage to be ≤0.05%. In the third stage, after the molten steel in the converter smelting process is fed and heated by electrodes in the second stage, and then heated to T2, aluminum particles are added to control the oxygen content in the molten steel to be ≤20ppm and the Al mass percentage to be 0.06-0.08%. Then, preheated ferromanganese with a mass percentage of 10%-20% is added. After the preheated ferromanganese is added for 1.5-2 minutes, the temperature of the molten steel is measured. When the detected temperature of the molten steel is lower than the set third target temperature T3, electrode heating is used to supplement the temperature. The electrode heating power P is determined according to formula (1), and the molten steel is heated to the third target temperature T3 by the electrode heating power P. The target characteristic depth of electrode heating is 0.6-0.8 times the actual molten pool depth, and the feeding rate is 0.3-1t / min. After adding the aluminum particles, CO2-Ar mixed gas is injected into the ladle through the bottom blower permeable brick in the form of pulse jet. The final Al mass percentage is controlled to be ≤0.07%. In the fourth stage, after the molten steel in the converter is smelted, it is fed and heated by electrodes in the third stage. After the temperature is replenished to T3, the blowing gas is stopped, the power is cut off, and it is left to stand for 5 to 30 minutes. The oxygen content at the end point is controlled to be ≤15ppm and Mn is 20% to 30%. Electrode heating power P = 150 × (T) 目标温度 -T 钢液温度 ) 1.2 ×e (-0.15*d) +20×V (1); Where V is the feeding rate (t / min); d is the target characteristic depth of electrode heating (m), d=k*H, k is the depth coefficient, k=1.1~1.2 in the first stage, k=1.0 in the second stage, and k=0.6~0.8 in the third stage; H is the molten pool depth.

2. The process for alloying ultra-low temperature high-manganese steel according to claim 1, characterized in that, In the converter smelting process, aluminum particles are added during the tapping process for strong deoxidation, and the final oxygen content in the molten steel is controlled to be ≤50ppm.

3. The process for alloying ultra-low temperature high-manganese steel according to claim 1, characterized in that, In the first stage, the flow rate of bottom-blown argon is 0.6–1.0 Nm³. 3 / min; In the second stage, the flow rate of bottom-blown argon is 1.0–1.5 Nm³. 3 / min; In the third stage, the CO2 volume percentage in the CO2-Ar mixture is 25-35%, and the bottom-blowing flow rate of the CO2-Ar mixture is 0.3-1.0 Nm³. 3 / min, injection pressure 0.1~0.2MPa, pulse frequency 5~20Hz, CO2 purity ≥99.9%.

4. The process for alloying ultra-low temperature high-manganese steel according to claim 1, characterized in that, The temperature of the preheated ferromanganese is 400–600°C.

5. The process for alloying ultra-low temperature high-manganese steel according to claim 1, characterized in that, The pre-melted slag balls comprise the following components by mass percentage: 35-40% CaO, 12-25% BaO, 2-4% Li2O, 15-20% Al2O3, 8-15% CaF2, 3-8% MgO, and 0.5-1.0% Ce2O3.

6. The process for alloying high-manganese steel at ultra-low temperatures according to claim 5, characterized in that, The diameter of the pre-melted slag balls is 5–20 mm.

7. The process for alloying ultra-low temperature high-manganese steel according to claim 1, characterized in that, The amount of the pre-melted slag balls used is 8-15 kg / t steel.

8. The process for alloying high-manganese steel at ultra-low temperatures according to claim 1, characterized in that, The first target temperature T1 is 1580℃~1600℃; the second target temperature T2 is 1530℃~1550℃; and the third target temperature T3 is 1520℃~1530℃.

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