Production method for increasing continuous casting furnace number of bloom bearing steel through RH vacuum refining

Abstract

The invention discloses a production method for increasing the number of continuous casting furnaces of bloom bearing steel through RH vacuum refining, and relates to the field of steelmaking, and the production method comprises the following steps: when a blowing parameter result output by an automatic steelmaking model reaches a preset standard, stopping converter blowing of a bearing steel raw material; an alloy material prepared in advance is added into the molten steel obtained after converter blowing, and purified molten steel is obtained; outputting a current micro-positive pressure control precision value according to the available model; ensuring that the purified molten steel is in a reducing atmosphere in a furnace of the LF refining process, and obtaining molten steel with a refining final slag target after the LF refining process; the molten steel with the refining final slag target is subjected to high-vacuum treatment; the method comprises the following steps: performing continuous casting on molten steel before continuous casting based on a continuous casting process of intrusive casting and whole-course protective casting to obtain a bearing steel continuous casting billet; the continuous casting furnace number of the bloom bearing steel is increased.

Description

Technical Field

[0001] The invention relates to the field of steelmaking, and in particular to a production method for increasing the number of continuous casting furnaces for large square billet bearing steel by RH vacuum refining. Background Art

[0002] Bearing steel GCr15 (Al content is 0.008-0.015%) is a high-performance alloy steel, mainly used to manufacture bearing balls and rollers. It has high hardness, strength and wear resistance. Since the contact area of ​​the bearing is very small during operation and is subjected to high-speed repeated and constantly changing stress, the quality requirements for bearing steel are relatively high. The purity of steel is closely related to its durability, so the content of gas and inclusions in the steel is very strict.

[0003] However, the aluminum added during the smelting process of bearing steel GCr15 will cause the molten steel to form a high-melting-point substance Al2O3, which will adhere to the nozzle wall and form nozzle nodules, causing serious molten steel flow problems, interrupting casting and affecting smooth production. At the same time, nozzle nodules lead to problems such as an increase in the stopper coefficient and liquid level fluctuations, affecting the surface quality of the ingot.

[0004] In the existing related technologies:

[0005] For example, Chinese Patent No. 202210757816.3 discloses a smelting process for increasing the number of continuous casting furnaces for small-section bearing steel, which includes electric furnace smelting, LF refining, RH refining, and 160mm*160mm continuous casting processes. For another example, Chinese Patent No. 201710045687.4 discloses a carbon deoxidation process for SWRY11 steel, which includes the purpose of improving the purity of molten steel; in the carbon deoxidation process, the converter can appropriately increase the final carbon content, and use the carbon in the steel during the converter steelmaking process for pre-deoxidation, and the converter controls the final carbon and oxygen content. For another example, Chinese Patent No. 202011001957.X discloses an LF refining method for controlling the nitrogen content in gear steel, which includes sealing the smelting station with argon, generating a slightly positive pressure atmosphere in the smelting furnace, and transferring the molten steel to the smelting station.

[0006] In summary, none of the above-mentioned related technologies involve solutions for increasing the number of continuous casting furnaces for 240mm*240mm square bearing steel. Therefore, there is an urgent need for a production method that can increase the number of continuous casting furnaces for large square billet bearing steel GCr15 while stabilizing the quality of the castings and improving production efficiency. Summary of the invention

[0007] In view of the problems in the related art, the present invention proposes a production method for increasing the number of continuous casting furnaces for large square billet bearing steel by RH vacuum refining, so as to overcome the above-mentioned technical problems existing in the existing related technology.

[0008] To this end, the specific technical solution adopted by the present invention is as follows:

[0009] A production method for increasing the number of continuous casting furnaces for large square billet bearing steel by RH vacuum refining, comprising:

[0010] When the blowing parameter result output by the automated steelmaking model reaches the preset standard, the converter blowing of the bearing steel raw material is stopped to obtain molten steel after converter blowing;

[0011] The pre-prepared alloy material is added into the molten steel after converter blowing to obtain the purified molten steel; according to the trained available model, the current micro-positive pressure control accuracy value is output; the micro-positive pressure operation mode and the current micro-positive pressure control accuracy value are adopted to ensure that the purified molten steel is in a reducing atmosphere in the furnace of the LF refining process, and after the LF refining process, the molten steel with the refining final slag target is obtained;

[0012] The RH vacuum process is used to subject the molten steel with the goal of refined final slag to high vacuum treatment to obtain the molten steel before continuous casting; based on the continuous casting process of invasive open pouring and full-process protective pouring, the molten steel before continuous casting is continuously cast using a long water nozzle and argon seal protective pouring to obtain a bearing steel continuous casting billet.

[0013] Further, when the blowing parameter result output by the automated steelmaking model reaches a preset standard, the converter blowing of the bearing steel raw material is stopped, and the molten steel obtained after the converter blowing includes:

[0014] The collected first model data is used as the first input data, and the carbon content of the molten steel is used as the first output data to train the static model in the automated steelmaking model, wherein the first model data includes the molten iron composition and the gas composition content;

[0015] The collected second model data is used as the second input data, and the endpoint carbon and temperature are used as the second output data to train the dynamic model in the automated steelmaking model, wherein the second model data includes the carbon content of the molten steel;

[0016] When the carbon content of molten steel calculated by the static model reaches the preset carbon content threshold, the dynamic model is activated;

[0017] When the end point carbon and temperature calculated by the dynamic model reach the preset target carbon and temperature range, the converter blowing of the bearing steel raw material is stopped to obtain molten steel after converter blowing;

[0018] Among them, the top and bottom combined blowing process is used to carry out converter blowing on the bearing steel raw materials.

[0019] Furthermore, the pre-prepared alloy material is added into the molten steel after converter blowing to obtain the purified molten steel, which comprises:

[0020] The slag basicity of the molten steel after converter blowing is controlled within a preset range by combining the double slag stops of the slide plate and the double slag stops of the slag stop cone;

[0021] During the steel-making process, various alloys including aluminum blocks are added into the molten steel after being blown in the converter through a high-level silo, and the aluminum blocks are used to deoxidize both the slag and the molten steel.

[0022] Furthermore, according to the trained available model, the output of the current micro-positive pressure control accuracy value includes:

[0023] Utilize the training data of the available model to optimize the model parameters of the linear regression algorithm to obtain a trained available model;

[0024] According to the available model and the model input data collected in real time, the current micro-positive pressure control accuracy value is calculated;

[0025] Among them, the training data of the model that can be used include the composition of the purified molten steel, related temperature data, furnace pressure data, furnace cover flue gas volume and micro-positive pressure control accuracy data.

[0026] Furthermore, the micro-positive pressure operation mode and the current micro-positive pressure control accuracy value are adopted to ensure that the purified molten steel is in a reducing atmosphere in the furnace of the LF refining process, and after the LF refining process, the molten steel with the refining final slag target is obtained, including:

[0027] Refining the purified molten steel using the LF refining process;

[0028] In the LF refining process, micro-positive pressure operation and the current micro-positive pressure control accuracy value are obtained to ensure the reducing atmosphere in the furnace, and the bottom blowing argon system is adopted throughout the process;

[0029] After the LF refining process, molten steel with the refined final slag target is obtained.

[0030] Further, the purified molten steel is refined by the LF refining process, including:

[0031] The LF refining process is started based on the preset voltage value and current value, so that the temperature of the purified molten steel exceeds the preset value, and a deoxidizer is added to the purified molten steel;

[0032] adding different amounts of silicon carbide to the purified molten steel in stages, and sampling the purified molten steel multiple times;

[0033] Aluminum beans are added to the purified molten steel before the first sampling, and the aluminum content is detected. When the aluminum content is greater than or equal to the aluminum content threshold, the aluminum content is made to reach the first target value at one time during the second sampling; when the aluminum content is less than the aluminum content threshold, the aluminum content is made to reach the second target value at one time, and is adjusted to the third target value when the furnace is started.

[0034] Furthermore, the whole process adopts the bottom blowing argon system including:

[0035] After the molten steel enters the station, the side blowing mode is started, and the air-permeable bricks are blown through and the slag surface of the molten steel is blown open; after the slag surface is blown open, the argon gas is adjusted to the power-on mode to ensure that the power transmission process can smoothly heat up and melt the slag;

[0036] Start the strong blowing mode to achieve slag washing and desulfurization; adjust the strong blowing mode to the strong stirring mode, and make the composition and temperature of the molten steel uniform when adding alloy;

[0037] After the composition and temperature of the molten steel are uniform, start the weak blowing mode and the soft blowing mode in sequence to make the inclusions in the molten steel float up.

[0038] Further, the RH vacuum process includes:

[0039] Configure the material of the vacuum tank in the RH vacuum process, the temperature of the molten steel in the tank, the high vacuum holding time during the tank washing process, and the circulation gas flow rate during the high vacuum process;

[0040] Control the argon blowing intensity in the RH vacuum process and use the slag surface insulation to cover the molten steel with the refined final slag target;

[0041] During the RH vacuum process, after the impregnated pipe is sprayed, the impregnated pipe is baked.

[0042] Furthermore, the continuous casting process based on the invasive open pouring and full protection pouring, and the method of using the long shroud and argon seal protection pouring includes:

[0043] Before starting the machine, check the argon gas management and the condition of the long nozzle. After putting the sealing ring on the long nozzle and making sure it is vertical, lock the manipulator;

[0044] Determine the start time of the ladle heating according to the distance between the shroud and the liquid level of the tundish; when transferring tundishes, clean the shroud from the tundish;

[0045] When the tundish reaches a preset weight, a carbon-free covering agent is added to the tundish, and when the liquid surface of the tundish turns red, carbonized rice husk is added;

[0046] When starting the first furnace during the pouring process, measure the temperature several times and then adjust to the preset pouring speed.

[0047] Furthermore, when subcontracting, the cleaning of the residues from the shroud includes:

[0048] When subcontracting, clean the bowl of the long nozzle of the shroud to remove the residue and steel;

[0049] After cleaning the bowl of the long nozzle, clean the residual slag at the bottom of the long nozzle.

[0050] The beneficial effects of the present invention are:

[0051] The present invention can increase the number of continuous casting furnaces for large square billet bearing steel from 8 furnaces to 10 furnaces or more. The molten steel does not produce liquid level fluctuations and nozzle nodules during the continuous casting process. The surface quality of the produced ingots is good and reaches the international advanced level. The products produced are widely used in high-end bearing parts. The converter of the present invention adopts a top and bottom combined blowing process, and the blowing process uses an automated steelmaking model of the LOMAS flue gas analysis system. The steel tapping adopts a double-blocking slide plate + a double-blocking slag cone. The temperature is quickly raised and the slag is melted to make white slag during the LF refining process, and the composition of the molten steel is controlled within the internal control range. After the LF treatment is completed, the temperature of the molten steel is controlled at 1540-1550°C. In the RH vacuum refining process, except for aluminum added in the early stage of RH, other alloys are not added or added in small amounts. The RH high vacuum (≤67Pa) time is controlled at 20-25min. After the RH treatment is completed, there is no calcification treatment, and the soft blowing operation is directly performed, and the soft blowing time is ≥30min. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0053] Figure 1 The present invention is a flowchart of a production method for increasing the number of continuous casting furnaces for large square billet bearing steel by RH vacuum refining according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] To further illustrate each embodiment, the present invention provides drawings, which are part of the disclosure of the present invention and are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, ordinary technicians in the field should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0055] According to an embodiment of the present invention, a production method for increasing the number of continuous casting furnaces for large square billet bearing steel by RH vacuum refining is provided.

[0056] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. Figure 1 As shown, the production method for increasing the number of continuous casting furnaces of large square billet bearing steel by RH vacuum refining according to an embodiment of the present invention comprises:

[0057] S1. When the blowing parameter result output by the automated steelmaking model reaches a preset standard, the converter blowing of the bearing steel raw material is stopped to obtain molten steel after converter blowing.

[0058] S2. Add the pre-prepared alloy material into the molten steel after converter blowing to obtain purified molten steel; output the current micro-positive pressure control accuracy value according to the trained available model; adopt the micro-positive pressure operation method and the current micro-positive pressure control accuracy value to ensure that the purified molten steel is in a reducing atmosphere in the furnace of the LF refining process, and obtain molten steel with the refining final slag target after the LF refining process.

[0059] S3. The molten steel with the goal of refined final slag is subjected to high vacuum treatment by using the RH vacuum process to obtain the molten steel before continuous casting; the molten steel before continuous casting is continuously cast based on the continuous casting process of invasive open pouring and full-process protective pouring, and the long water inlet and argon seal protective pouring are used to obtain the bearing steel continuous casting billet.

[0060] In one embodiment, when the blowing parameter result output by the automated steelmaking model reaches a preset standard, the converter blowing of the bearing steel raw material is stopped, and the molten steel after the converter blowing is obtained includes:

[0061] The collected first model data is used as the first input data, and the carbon content of the molten steel is used as the first output data to train the static model in the automated steelmaking model, and the first model data includes the molten iron composition and the gas component content.

[0062] The collected second model data is used as the second input data, and the endpoint carbon and temperature are used as the second output data to train the dynamic model in the automated steelmaking model, and the second model data includes the carbon content of the molten steel.

[0063] When the carbon content of molten steel calculated by the static model reaches the preset carbon content threshold, the dynamic model is activated.

[0064] When the end point carbon and temperature calculated by the dynamic model reach the preset target carbon and temperature range, the converter blowing of the bearing steel raw material is stopped to obtain molten steel after converter blowing.

[0065] Among them, the top and bottom combined blowing process is used to carry out converter blowing on the bearing steel raw materials.

[0066] In one embodiment, adding the pre-prepared alloy material into the molten steel after converter blowing to obtain the purified molten steel comprises:

[0067] The slag basicity of the molten steel after converter blowing is controlled within a preset range by combining the double slag stops of the slide plate with the double slag stops of the slag stop cone.

[0068] During the steel-making process, various alloys including aluminum blocks are added into the molten steel after being blown in the converter through a high-level silo, and the aluminum blocks are used to deoxidize both the slag and the molten steel.

[0069] In one embodiment, according to the trained available model, outputting the current micro-positive pressure control accuracy value includes:

[0070] The model parameters of the linear regression algorithm are optimized using the training data of the available model to obtain a trained available model.

[0071] Based on the available model and the model input data collected in real time, the current micro-positive pressure control accuracy value is calculated.

[0072] Among them, the training data of the model that can be used include the composition of the purified molten steel, related temperature data, furnace pressure data, furnace cover flue gas volume and micro-positive pressure control accuracy data.

[0073] In one embodiment, a micro-positive pressure operation mode and a current micro-positive pressure control accuracy value are adopted to ensure that the purified molten steel is in a reducing atmosphere in the furnace of the LF refining process, and after the LF refining process, molten steel having a refined final slag target is obtained, including:

[0074] The purified molten steel is refined in the LF refining process.

[0075] During the LF refining process, micro-positive pressure operation is adopted and the current micro-positive pressure control accuracy value is obtained to ensure the reducing atmosphere in the furnace, and the bottom blowing argon system is adopted throughout the process.

[0076] After the LF refining process, molten steel with the refined final slag target is obtained.

[0077] In one embodiment, refining the purified molten steel using the LF refining process includes:

[0078] The LF refining process is started based on the preset voltage and current values, so that the temperature of the purified molten steel exceeds the preset value, and a deoxidizer is added to the purified molten steel.

[0079] Different amounts of silicon carbide were added to the purified molten steel in stages, and the purified molten steel was sampled multiple times.

[0080] Aluminum beans are added to the purified molten steel before the first sampling, and the aluminum content is detected. When the aluminum content is greater than or equal to the aluminum content threshold, the aluminum content is made to reach the first target value at one time during the second sampling; when the aluminum content is less than the aluminum content threshold, the aluminum content is made to reach the second target value at one time, and is adjusted to the third target value when the furnace is started.

[0081] In one embodiment, the whole process adopts the bottom blowing argon system including:

[0082] After the molten steel enters the station, the side-blowing mode is started, and the air bricks are blown through and the slag surface of the molten steel is blown open; after the slag surface is blown open, the argon gas is adjusted to the power-on mode to allow the power transmission process to steadily heat up and melt the slag.

[0083] Start the strong blowing mode to achieve slag washing and desulfurization; adjust the strong blowing mode to the strong stirring mode, and make the composition and temperature of the molten steel uniform when adding alloy.

[0084] After the composition and temperature of the molten steel are uniform, start the weak blowing mode and the soft blowing mode in sequence to make the inclusions in the molten steel float up.

[0085] In one embodiment, the RH vacuum process includes:

[0086] Configure the material of the vacuum tank in the RH vacuum process, the temperature of the molten steel in the tank washing process, the high vacuum holding time during the tank washing process, and the circulation gas flow rate during the high vacuum process.

[0087] The argon blowing intensity in the RH vacuum process is controlled, and the molten steel with the goal of refined final slag is covered with slag surface insulation.

[0088] During the RH vacuum process, after the impregnated pipe is sprayed, the impregnated pipe is baked.

[0089] In one embodiment, a continuous casting process based on invasive open pouring and full-process protective pouring, and a method of using a long shroud and argon sealing protective pouring includes:

[0090] Before starting the machine, check the argon gas management and the condition of the long nozzle. After putting the sealing ring on the long nozzle and making sure it is vertical, lock the manipulator.

[0091] The time to start heating the ladle is determined according to the distance between the shroud and the liquid level of the tundish; when transferring the ladle, the shroud is cleaned from the tundish.

[0092] When the tundish reaches a preset weight, a carbon-free covering agent is added into the tundish, and when the liquid surface of the tundish turns red, carbonized rice husk is added.

[0093] When starting the first furnace during the pouring process, measure the temperature several times and then adjust to the preset pouring speed.

[0094] In one embodiment, when subcontracting, cleaning the shroud includes:

[0095] When subcontracting, the bowl of the long nozzle should be cleaned of residues and residual steel.

[0096] After cleaning the bowl of the long nozzle, clean the residual slag at the bottom of the long nozzle.

[0097] In order to facilitate understanding of the above technical solutions of the present invention, the above technical solutions of the present invention are further explained below from the perspectives of architecture and principle.

[0098] The technical scheme adopted by the present invention is: adopting converter blowing, LF refining, RH refining and 240mm*240mm square billet continuous casting process. The converter adopts the top and bottom combined blowing process, the blowing process uses the automated steelmaking model of the LOMAS flue gas analysis system, the steel tapping adopts the double-blocking of the slide plate + the double-blocking of the slag cone, the LF refining process adopts the micro-positive pressure operation (based on the slight smoke in the furnace), ensures the reducing atmosphere in the furnace, the white slag time is maintained ≥20min, reduces the secondary oxidation of the molten steel in the process, the RH high vacuum holding time is controlled at 20-25min, the molten steel is not exposed in the soft blowing process, the soft blowing time is ≥30min, the continuous casting process adopts the light pressure reduction process, the carbon-free covering agent 03 type is added to the tundish, and the SPH-C189 / VV1 protective slag is used to protect the casting throughout the whole process.

[0099] The LF refining process of the present invention adopts a micro-positive pressure operation (based on slight smoke in the furnace) to ensure a reducing atmosphere in the furnace, and the frequency of the dust removal fan is controlled at 25 Hz. A high-speed position is adopted in the early stage, and a large current is used to quickly slag and heat up.

[0100] In the LF refining process of the present invention, the timing of adding the deoxidizer is to start injecting the deoxidizer for rapid deoxidation after the predicted temperature of the molten steel is ≥1490°C, the total amount of silicon carbide is controlled at 160-200kg, 80-100kg in the early stage (10-30kg of carbon powder can be added for the overoxidation furnace), 60-80kg in the middle stage, and 20-40kg in the later stage; the amount of aluminum beans is controlled at 0-20kg, and the aluminum beans are added before starting the furnace 311.

[0101] The temperature of the start-up furnace 311 is ≥1520℃, the continuous casting furnace is ≥1510℃, the process temperature reaches above the subcontract target temperature, and low-speed heat preservation is adopted in the later stage. When sampling for the first time, the actual flow rate of argon can reach more than 300NL / min, and the pressure is ≥0.3Mpa.

[0102] A smelting process flow of RH vacuum refining to increase the number of continuous casting furnaces for large square billet bearing steel is: 170t converter-170tLF refining furnace-170tRH vacuum refining-240mm*240mm square billet continuous casting. The LF+RH double refining process can not only remove the inclusion content in the molten steel, but also control the [H] in the molten steel to be less than 1.2ppm, [O] to be less than 10ppm, greatly improving the purity and castability of the molten steel. The specific process control of each process is as follows:

[0103] Production organization and control: After the slag splashing of the first converter begins, the "Production Time Plan" will be issued in a timely manner, and each process will strictly implement the key node control requirements (LF: -5min to +1min, other processes: -3min to +3min).

[0104] The crane hoisting sequence requirements in the production process are: ②LF→RH, ①BOF→LF (LF is required to leave the station first and then enter the station), ③RH-CC, ④CC→hot repair process, ⑤hot repair process→BOF ladle car; C1 crane stroke: BOF-1#LF-(RH)-CC, C2 crane stroke: BOF-2#LF-(RH)-CC, the priority requirements in time and space are: bearing steel>ordinary steel, C2>C1. It should be noted that: LF in the present invention refers to the ladle refining furnace, which is one of the main methods of refining outside the furnace; RH refers to the vacuum circulation degassing method of molten steel, which is a method of refining; BOF refers to the oxygen top-blown converter steelmaking method, which is the abbreviation of the English name of the basic oxygen steelmaking furnace, basic oxygen furnace; CC refers to the abbreviation of continuous steel casting; C1 refers to the crane code of the workshop molten steel casting span; C2 refers to the crane code of the workshop molten steel casting span.

[0105] Ladle control: Normally use 6 ladles for turnover, and there should be no residue on the slag line, ladle wall, ladle mouth and drain port; each furnace is required to purge the air bricks, and the air permeability requirement (south / north) is ≥20Nm 3 / h; the ladle temperature and ladle condition information are transmitted to the converter, LF refining furnace and RH process furnace.

[0106] Converter process: select D and E type molten iron (D type molten iron refers to conventional elements / %: C ≥ 3.50, Si: 0.10-0.60, Mn ≤ 1.00, S, P ≤ 0.150, residual elements / %: Cr, Ni, Cu, Mo ≤ 0.05, As, Pb ≤ 0.005, Sn, Sb ≤ 0.003; E type molten iron refers to conventional elements / %: C ≥ 3.50, Si: 0.10-0.60, Mn ≤ 1.00, S ≤ 0.150, P ≤ 0.140, residual elements / %: Cr, Ni, Cu, Mo ≤ 0.03, As ≤ 0.008, Pb ≤ 0.010, Sn ≤ 0.007, Sb ≤ 0.010).

[0107] The converter adopts the automated steelmaking model of the LOMAS flue gas analysis system, which consists of a static model and a dynamic model. The principles of the static model and the dynamic model: When the system receives the blowing start signal, the static control model searches for the best raw material ratio based on the raw material conditions, and determines the blowing method based on the actual ingredients. First, the model data is collected, which includes but is not limited to the chemical composition and gas composition content, such as molten iron composition and flue gas composition. The collected endpoint temperature and carbon composition are divided into a training set and a validation set. The selected model is trained using the training set; during the production process, the characteristic data of the endpoint temperature and carbon composition are obtained in real time and input into the model, and the model will output the best blowing method based on these data. During the blowing process, the first stage automatically adds materials and supplies oxygen according to the static model setting values, and calculates the endpoint molten steel temperature based on the molten iron composition, temperature, and slag information.

[0108] The dynamic model consists of furnace gas carbon determination, temperature prediction, and splash prediction modules. The dynamic control model mainly collects and analyzes the furnace gas composition escaping from the converter mouth through the sampling system and mass spectrometer after the carbon-oxygen reaction in the furnace tends to equilibrium 2 minutes after the last smelting. The decarburization rate is calculated based on the change in the furnace gas composition, and the operator is provided with the change in carbon content in the steel 2 minutes before the end of the blowing. The model determines the blowing end point based on the end point carbon and temperature calculated by the dynamic model and the converter flue gas change curve, and divides the collected temperature and carbon composition into training set and validation set. The selected machine learning model is trained using the training set, and the end point carbon and temperature are calculated using the linear regression method. If there is a linear relationship between temperature and carbon content, linear regression is a simple and effective method. A model can be established through linear regression: Y=AX1+BX2+CX3+DX4, where Y represents carbon; Xi represents the temperature parameter (%), i represents one of 1, 2, 3, 4; A, B, C and D all represent the corrected dimensionless quantity of temperature; when A=0.04%, B=0.12%, C=D=0, and X1=0.12, X2=0.5, Y=0.0648% is obtained.

[0109] When the static model calculates that the carbon content of molten steel reaches 0.18%, the dynamic model can be activated by referring to the flue gas analysis trend of the LOMAS system. The dynamic model uses the flue gas analysis results of the LOMAS system for calculation. When the calculation results enter the preset target carbon and temperature range, the model will make timely judgments based on the results and send out a signal to stop blowing, which plays a good guiding role in improving the carbon content of the converter end point, reducing the original oxygen content of the molten steel, and reducing the generation of inclusions.

[0110] The final slag basicity is controlled at 2.8-3.2, which is conducive to the early removal of harmful elements such as P; the converter tapping temperature is controlled at >1620℃, and the double slag blocks of the slide plate + slag block cone are used to achieve zero slag discharge in the converter, reduce aluminum loss, and effectively improve the purity of molten steel.

[0111] Various alloys are added through high-level silos, and aluminum cakes are manually added during the steel-making process. Since aluminum cakes are light, they easily float on the slag layer and only react with the slag, but cannot remove oxygen from the molten steel. Aluminum wire is directly fed into the molten steel, and the slag surface is not fully deoxidized. The slag on the surface of the molten steel reacts with AL to produce a large amount of Al2O3 inclusions, which causes the purity of the molten steel to deteriorate. Therefore, the converter of the present invention uses large aluminum blocks for deoxidation. The size and weight of the large aluminum blocks are relatively large. If the size is too large, the alloy hole of the converter cannot be added. If the size is too small, it is easy to be washed to the slag surface by the steel flow. In order to obtain a suitable size, aluminum blocks of different specifications are purchased for experimental verification. Through data comparison, it is determined to purchase large aluminum blocks with AL%>99.5, length 30×width 25×thickness 10, and a weight of about 20±0.2Kg). After the slag enters the molten steel, both the slag and the molten steel can be fully deoxidized, and the recovery rate is also significantly higher than that of the aluminum cake. At the same time, the large aluminum blocks are selected to be added in the steel tapping process instead of in the LF, in order to ensure that large particle inclusions can fully float up and effectively improve the purity of the molten steel.

[0112] LF refining process: The power supply of LF refining ensures the reducing atmosphere in the furnace throughout the whole process. Using artificial intelligence linear regression algorithm, the furnace pressure, temperature and composition of the refining process are collected every 30 seconds. The model parameters are optimized according to the data such as the outlet temperature, composition, and alloy addition amount, so that the deviation between the model calculation result and the actual result is controlled within a certain range, and a usable model is obtained. During the use of the model, the calculated value is adjusted according to the model calculation result. The calculation formula is LLG = (LyCyt1-LyC40t40) / (C120t120-C40t40), where LLG is the flue gas volume of the furnace cover, and the temperature is 120°C; Ly is the original flue gas volume (m 3 / h), the temperature is 1650℃; when CY, C120, C40 are 1650, 120 and 40℃ respectively, the constant pressure volumetric specific heat of flue gas [kJ / (m 3 .℃)], which can be calculated according to the formula CY=1.295+0.00112t, are 1.4798, 1.3084 and 1.2995 respectively; t1, t120 and t40 are the original flue gas, furnace cover flue gas and workshop ambient temperature respectively, and their values ​​can be taken as 1650℃, 120℃ and 40℃ respectively, which automatically optimizes the micro-positive pressure control accuracy, can ensure the micro-positive pressure atmosphere in the furnace, prevent the secondary oxidation of molten steel, and improve the purity of molten steel.

[0113] In the early stage of refining (3-11min), high-grade position (voltage 401-430V) and large current (current 44870A) are used to quickly heat up and electrify the slag. When the temperature of the molten steel is expected to be ≥1490℃, the deoxidizer is injected for rapid slag surface deoxidation. The total amount of silicon carbide is controlled at 160-200kg, 80-100kg is added in the early stage (10-30kg carbon powder can be added for the overoxidation furnace), 60-80kg is added in the middle stage, and 20-40kg is added in the later stage; the amount of aluminum beans is controlled at 0-20kg, and aluminum beans are added before the first sampling to achieve the purpose of quickly making white slag; when the first Al is ≥0.020%, the aluminum composition shall not be adjusted, and the aluminum shall be adjusted to the right position at one time according to the second sampling composition, and the aluminum composition shall not be adjusted at the later stage; when the first Al is <0.020%, aluminum is supplemented to 0.030% at one time according to the aluminum composition, and the furnace is adjusted to 0.035% when the machine is started.

[0114] The whole process adopts the bottom blowing argon system, and the argon control is divided into 6 modes: side blowing, strong blowing, strong stirring, power on, weak blowing, and soft blowing. After the molten steel enters the station, connect the argon pipe, click the side blowing (straight pipeline gas), blow through the permeable brick, and the argon flow rate is 1500NL / min at this time to blow open the molten steel slag surface; after the slag surface is blown open, in the early stage of refining (3-8min), adjust the argon to the power-on mode, and the argon flow rate in the power-on mode is controlled at 200-400NL / min. The main purpose is to ensure the smooth slag temperature rise during the power transmission process and ensure heat transfer; during the refining process (9-12min), adjust the argon to the strong blowing mode, and the argon flow rate in the strong blowing mode is 800-1000NL / min. The main purpose is to desulfurize through slag washing. After refining sampling (13- 15min) is adjusted to strong stirring mode, and the argon flow rate in strong stirring mode is 400-600NL / min, which is mainly for uniform temperature of molten steel composition and rapid deoxidation when adding alloy; after the composition temperature is uniform, the argon is adjusted to weak blowing mode, and the argon flow rate is 80-150NL / min. The molten steel is left to stand for a waiting time, and the white slag time is ensured to be ≥20min. The main purpose is to promote the collision of inclusions and promote the floating of molten steel inclusions; after the molten steel refining is completed, the argon is adjusted to soft blowing mode, and the argon flow rate is 30-100NL / min. The standard is that the molten steel does not leak, the slag surface fluctuates slightly, and the molten steel inclusions are fully floated.

[0115] After LF refining treatment, the final slag targets are: CaO: 53-58%, SiO2: 9-12%, AL2O3: 25-30%.

[0116] RH vacuum process: Before the production of bearing steel, the vacuum tank must not be cold-started. (The tank must be cleaned after the vacuum tank is cold or the baking time exceeds 4 hours) The steel type for washing the tank should be aluminum-killed steel, the temperature of the steel water for washing the tank should not be less than 1610℃, and the high vacuum holding time during the washing process should be ≥5min.

[0117] Strictly control the high vacuum holding time, which is controlled within 20-25 minutes; the high vacuum process circulation gas flow is controlled within 100-130m 3 / h.

[0118] During the soft blowing process, the argon blowing intensity is strictly controlled, the slag surface is completely covered with insulation, the slag surface is fluctuating, and the molten steel does not turn red.

[0119] The immersed pipe is not repaired by gunning. If it is repaired by gunning, it needs to be baked with a top gun for more than 10 minutes.

[0120] After RH high vacuum treatment, the molten steel [H] is guaranteed to be less than 1.2ppm and [O] is less than 10ppm.

[0121] Continuous casting process: The continuous casting process adopts invasive open pouring with full-process protection pouring, and long nozzle and argon seal protection pouring are used from the continuous casting ladle (molten steel ladle) to the tundish.

[0122] Before starting the machine, manually test the argon gas and check whether the pipeline is leaking, gas blowby, or blocked. The argon sealing tube is not damaged. After putting on the sealing ring, put the palm of your hand on the bowl of the long water outlet. Under the conventional process argon flow rate, you can clearly feel the gas atmosphere. The long water outlet argon sealing flow rate is set at 100L / min.

[0123] Before starting the machine, check and confirm that the shroud is free of damage or bumps. The shroud that is obviously damaged or bumped must not be used. The shroud must be used with a sealing ring. The large package of shrouds should be replaced every 5 furnaces.

[0124] After the long shroud is put on and confirmed to be vertical, lock the manipulator, visually position the long shroud of the large ladle about 10cm away from the liquid surface of the middle ladle to command the large ladle to start pouring. During the pouring process, the slide plate is opened by jogging, and the large ladle is lowered into place immediately after the pouring is normal. This is conducive to shortening the oxidation time of molten steel when pouring and reducing secondary oxidation of molten steel.

[0125] During the pouring process, observe whether the long nozzle is vertical. When transferring the goods, the residue and residual steel in the bowl of the long nozzle need to be cleaned. After the bowl is cleaned, the residual steel slag at the bottom of the nozzle also needs to be cleaned to avoid direct insertion into the molten steel and affecting the purity of the molten steel.

[0126] When the tonnage of the middle ladle reaches 20-25 tons, add 500kg of carbon-free covering agent 03 at one time to fully cover the molten steel. During the process, add an appropriate amount of carbonized rice husk according to the redness of the liquid surface in the middle ladle. It is best if the liquid surface moves slightly and does not turn red.

[0127] During the pouring process, the temperature is controlled at 20-30℃. Under normal circumstances, the temperature of the first furnace is manually measured 2-3 times and then adjusted to the normal casting speed of 1.10m / min. Cast the furnaces continuously to avoid manual temperature measurement to prevent secondary oxidation of the molten steel surface due to too many temperature measurements.

[0128] The chemical composition and mass percentage of the continuous casting billet are:

[0129] C: 0.96-1.01%, Si: 0.18-0.28%, Mn: 0.28-0.38%, P≤0.020%, S≤0.010%, Cr: 1. 41-1.50%, AL: 0.008-0.015%, Ti≤0.0030%, Mo≤0.05%, Ni≤0.10%, Ca≤0.0010%.

[0130] A specific production example of the implementation of the present invention: A production method for increasing the number of continuous casting furnaces for large square billet bearing steel by RH vacuum refining adopts the following specific process.

[0131] Embodiment 1:

[0132] 1) Bearing steel composition control, chemical composition and mass percentage are shown in Table 1.

[0133] 2) Bearing steel process flow: 170t converter - 170tLF refining furnace - 170tRH vacuum refining - 240mm*240mm square billet continuous casting.

[0134] 3) The final carbon content of the converter is controlled at 0.10%, the tapping temperature is 1640℃, the slag basicity is 3.0, the final oxygen content of the auxiliary gun TSo is 345ppm, the slide plate double block + slag cone double block are adopted, the high-level silo is automatically fed, and when 1 / 5 of the steel is tapped, large aluminum blocks are manually added for deoxidation.

[0135] 4) During the whole process of LF refining, the furnace is powered on with reducing atmosphere and slightly positive pressure operation (based on slight smoke in the furnace). In the early stage of refining, gear 4 (386V / 44870A) is used to quickly heat up, deslagging and make white slag. When the molten steel temperature is expected to be ≥1490℃, deoxidizer (silicon carbide + aluminum beans) is added for rapid deoxidation. The target components of the final slag are CaO: 53-58%, SiO2: 9-12%, AL2O3: 25-30%, ensuring that the white slag time is ≥20min, promoting the floating of molten steel inclusions and ensuring the purity of the molten steel.

[0136] 5) RH adopts deep treatment, the high vacuum (≤67Pa) holding time is controlled at 23min, and the soft blowing time is ≥30min. After RH high vacuum treatment, the molten steel [H] is less than 1.2ppm, and [O] is less than 10ppm.

[0137] 6) Continuous casting adopts invasive pouring and full-process protective pouring. Long shroud and argon seal protective pouring are adopted from ladle to tundish. The superheat of continuous casting tundish is controlled at 28℃. Carbon-free covering agent 03 is added at the start of pouring. The argon seal flow rate of the long shroud is controlled at 100L / min. Special protective slag is added when the molten steel covers the side holes of the immersion shroud to control heat transfer and lubrication, providing good cooling conditions for the ingot. After the machine is started normally, the pulling speed is controlled at 1.10m / min.

[0138] 7) After the implementation of the present invention, the number of continuous casting furnaces for large square bloom bearing steel is 10, and the surface quality of the detected continuous casting billets is good.

[0139] Embodiment 2:

[0140] 1) Bearing steel composition control, chemical composition and mass percentage are shown in Table 1.

[0141] 2) Bearing steel process flow: 170t converter - 170tLF refining furnace - 170tRH vacuum refining - 240mm*240mm square billet continuous casting.

[0142] 3) The final carbon content of the converter is controlled at 0.13%, the tapping temperature is 1638℃, the slag basicity is 3.1, the final oxygen content of the auxiliary gun TSo is 330ppm, the slide plate double block + slag cone double block are adopted, the high-level silo is automatically fed, and large aluminum blocks are manually added for deoxidation when 1 / 5 of the steel is tapped.

[0143] 4) During the whole process of LF refining, the furnace is powered on with reducing atmosphere and slightly positive pressure operation (based on slight smoke in the furnace). In the early stage of refining, gear 4 (386V / 44870A) is used to quickly heat up, deslagging and make white slag. When the molten steel temperature is expected to be ≥1490℃, deoxidizer (silicon carbide + aluminum beans) is added for rapid deoxidation. The target components of the final slag are CaO: 53-58%, SiO2: 9-12%, AL2O3: 25-30%, ensuring that the white slag time is ≥20min, promoting the floating of molten steel inclusions and ensuring the purity of the molten steel.

[0144] 5) RH adopts deep treatment, the high vacuum (≤67Pa) holding time is controlled at 21min, and the soft blowing time is ≥30min. After RH high vacuum treatment, the molten steel [H] is less than 1.2ppm, and [O] is less than 10ppm.

[0145] 6) Continuous casting adopts invasive pouring and full-process protective pouring. Long nozzle and argon seal protective pouring are adopted from ladle to tundish. The superheat of continuous casting tundish is controlled at 27℃. Carbon-free covering agent 03 is added at the start of pouring. The argon seal flow rate of the long nozzle is controlled at 100L / min. Special protective slag is added when the molten steel covers the side holes of the immersion nozzle to control heat transfer and lubrication, provide good cooling conditions for the ingot, and the pulling speed is controlled at 1.10m / min after normal startup.

[0146] 7) After the implementation of the present invention, the number of continuous casting furnaces for large square bloom bearing steel is 10, and the surface quality of the detected continuous casting billets is good.

[0147] Embodiment three:

[0148] 1) Bearing steel composition control, chemical composition and mass percentage are shown in Table 1.

[0149] 2) Bearing steel process flow: 170t converter - 170tLF refining furnace - 170tRH vacuum refining - 240mm*240mm square billet continuous casting.

[0150] 3) The final carbon content of the converter is controlled at 0.16%, the tapping temperature is 1632°C, the slag basicity is 3.0, the final oxygen content of the auxiliary gun TSo is 308ppm, the slide plate double block + slag cone double block are used, the high-level silo is automatically fed, and large aluminum blocks are manually added for deoxidation when 1 / 5 of the steel is tapped.

[0151] 4) During the whole process of LF refining, the furnace is powered on to maintain a reducing atmosphere, and a slightly positive pressure operation is adopted (based on slight smoke in the furnace). In the early stage of refining, the 3rd gear (401V / 43190A) is used for rapid heating, slagging and white slag production. After the molten steel temperature is expected to be ≥1490℃, deoxidizer (silicon carbide + aluminum beans) is introduced for rapid deoxidation. The target components of the final slag are CaO: 53-58%, SiO2: 9-12%, AL2O3: 25-30%, ensuring that the white slag time is ≥20min, promoting the floating of molten steel inclusions and ensuring the purity of the molten steel.

[0152] 5) RH adopts deep treatment, the high vacuum (≤67Pa) holding time is controlled at 25min, and the soft blowing time is ≥30min. After RH high vacuum treatment, the molten steel [H] is less than 1.2ppm, and [O] is less than 10ppm.

[0153] 6) Continuous casting adopts invasive pouring and full-process protective pouring. Long nozzle and argon seal protective pouring are adopted from ladle to tundish. The superheat of continuous casting tundish is controlled at 26℃. Carbon-free covering agent 03 is added at the start of pouring. The argon seal flow rate of the long nozzle is controlled at 100L / min. Special protective slag is added when the molten steel covers the side holes of the immersion nozzle to control heat transfer and lubrication, provide good cooling conditions for the ingot, and the pulling speed is controlled at 1.10m / min after normal startup.

[0154] 7) After the implementation of the present invention, the number of continuous casting furnaces for large square bloom bearing steel is 10, and the surface quality of the detected continuous casting billets is good.

[0155] Embodiment 4:

[0156] 1) Bearing steel composition control, chemical composition and mass percentage are shown in Table 1.

[0157] 2) Bearing steel process flow: 170t converter - 170tLF refining furnace - 170tRH vacuum refining - 240mm*240mm square billet continuous casting.

[0158] 3) The final carbon content of the converter is controlled at 0.16%, the tapping temperature is 1642℃, the slag basicity is 3.0, the final oxygen content of the auxiliary gun TSo is 299ppm, the slide plate double block + slag cone double block are adopted, the high-level silo is automatically fed, and large aluminum blocks are manually added for deoxidation when 1 / 5 of the steel is tapped.

[0159] 4) During the whole process of LF refining, the furnace is powered on with reducing atmosphere and slightly positive pressure operation (based on slight smoke in the furnace). In the early stage of refining, gear 4 (386V / 44870A) is used to quickly heat up, deslagging and make white slag. When the molten steel temperature is expected to be ≥1490℃, deoxidizer (silicon carbide + aluminum beans) is added for rapid deoxidation. The target components of the final slag are CaO: 53-58%, SiO2: 9-12%, AL2O3: 25-30%, ensuring that the white slag time is ≥20min, promoting the floating of molten steel inclusions and ensuring the purity of the molten steel.

[0160] 5) RH adopts deep treatment, the high vacuum (≤67Pa) holding time is controlled at 22min, and the soft blowing time is ≥30min. After RH high vacuum treatment, the molten steel [H] is less than 1.2ppm, and [O] is less than 10ppm.

[0161] 6) Continuous casting adopts invasive pouring and full-process protective pouring. Long nozzle and argon seal protective pouring are adopted from ladle to tundish. The superheat of continuous casting tundish is controlled at 26℃. Carbon-free covering agent 03 is added at the start of pouring. The argon seal flow rate of the long nozzle is controlled at 100L / min. Special protective slag is added when the molten steel covers the side holes of the immersion nozzle to control heat transfer and lubrication, provide good cooling conditions for the ingot, and the pulling speed is controlled at 1.10m / min after normal startup.

[0162] 7) After the implementation of the present invention, the number of continuous casting furnaces for large square bloom bearing steel is 10, and the surface quality of the detected continuous casting billets is good.

[0163] Table 1 Chemical composition and mass percentage of produced bearing steel

[0164]

[0165]

[0166] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A production method for increasing the number of continuous casting furnaces for large square billet bearing steel by RH vacuum refining, characterized in that: include: When the blowing parameter result output by the automated steelmaking model reaches the preset standard, the converter blowing of the bearing steel raw material is stopped to obtain molten steel after converter blowing; The pre-prepared alloy material is added into the molten steel after converter blowing to obtain the purified molten steel; according to the trained available model, the current micro-positive pressure control accuracy value is output; the micro-positive pressure operation mode and the current micro-positive pressure control accuracy value are adopted to ensure that the purified molten steel is in a reducing atmosphere in the furnace of the LF refining process, and after the LF refining process, the molten steel with the refining final slag target is obtained; The RH vacuum process is used to subject the molten steel with the goal of refined final slag to high vacuum treatment to obtain the molten steel before continuous casting; based on the continuous casting process of invasive open pouring and full-process protective pouring, the molten steel before continuous casting is continuously cast using a long water nozzle and argon seal protective pouring to obtain a bearing steel continuous casting billet.

2. The method for increasing the number of continuous casting furnaces for large square billet bearing steel by RH vacuum refining according to claim 1 is characterized in that: When the blowing parameter result output by the automated steelmaking model reaches a preset standard, stopping the converter blowing of the bearing steel raw material to obtain the molten steel after the converter blowing includes: The collected first model data is used as the first input data, and the carbon content of the molten steel is used as the first output data to train the static model in the automated steelmaking model, wherein the first model data includes the molten iron composition and the gas composition content; The collected second model data is used as the second input data, and the endpoint carbon and temperature are used as the second output data to train the dynamic model in the automated steelmaking model, wherein the second model data includes the carbon content of the molten steel; When the carbon content of molten steel calculated by the static model reaches the preset carbon content threshold, the dynamic model is activated; When the end point carbon and temperature calculated by the dynamic model reach the preset target carbon and temperature range, the converter blowing of the bearing steel raw material is stopped to obtain molten steel after converter blowing; Among them, the bearing steel raw materials are blown in a converter using the top and bottom combined blowing process.

3. The method for increasing the number of continuous casting furnaces for large square billet bearing steel by RH vacuum refining according to claim 1 is characterized in that: The step of adding the pre-prepared alloy material into the molten steel after converter blowing to obtain the purified molten steel comprises: The slag basicity of the molten steel after converter blowing is controlled within a preset range by combining the double slag stops of the slide plate and the double slag stops of the slag stop cone; During the steel-making process, various alloys including aluminum blocks are added into the molten steel after being blown in the converter through a high-level silo, and the aluminum blocks are used to deoxidize both the slag and the molten steel.

4. The method for increasing the number of continuous casting furnaces for large square billet bearing steel by RH vacuum refining according to claim 1 is characterized in that: The output of the current micro-positive pressure control accuracy value according to the trained available model includes: Utilize the training data of the available model to optimize the model parameters of the linear regression algorithm to obtain a trained available model; According to the available model and the model input data collected in real time, the current micro-positive pressure control accuracy value is calculated; Among them, the training data of the model that can be used include the composition of the purified molten steel, related temperature data, furnace pressure data, furnace cover flue gas volume and micro-positive pressure control accuracy data.

5. The method for increasing the number of continuous casting furnaces for large square billet bearing steel by RH vacuum refining according to claim 1 is characterized in that: The micro-positive pressure operation mode and the current micro-positive pressure control accuracy value are used to ensure that the purified molten steel is in a reducing atmosphere in the furnace of the LF refining process, and after the LF refining process, molten steel with the refining final slag target is obtained, including: Refining the purified molten steel using the LF refining process; In the LF refining process, micro-positive pressure operation and the current micro-positive pressure control accuracy value are obtained to ensure the reducing atmosphere in the furnace, and the bottom blowing argon system is adopted throughout the process; After the LF refining process, molten steel with the refined final slag target is obtained.

6. The method for increasing the number of continuous casting furnaces for bloom bearing steel by RH vacuum refining according to claim 5, characterized in that: The LF refining process for refining the purified molten steel comprises: The LF refining process is started based on the preset voltage value and current value, so that the temperature of the purified molten steel exceeds the preset value, and a deoxidizer is added to the purified molten steel; adding different amounts of silicon carbide to the purified molten steel in stages, and sampling the purified molten steel multiple times; Aluminum beans are added to the purified molten steel before the first sampling, and the aluminum content is detected. When the aluminum content is greater than or equal to the aluminum content threshold, the aluminum content is made to reach the first target value at one time during the second sampling; when the aluminum content is less than the aluminum content threshold, the aluminum content is made to reach the second target value at one time, and is adjusted to the third target value when the furnace is started.

7. The method for increasing the number of continuous casting furnaces for bloom bearing steel by RH vacuum refining according to claim 5, characterized in that: The bottom blowing argon system used throughout the process includes: After the molten steel enters the station, the side blowing mode is started, and the air-permeable bricks are blown through and the slag surface of the molten steel is blown open; after the slag surface is blown open, the argon gas is adjusted to the power-on mode to ensure that the power transmission process can smoothly heat up and melt the slag; Start the strong blowing mode to achieve slag washing and desulfurization; adjust the strong blowing mode to the strong stirring mode, and make the composition and temperature of the molten steel uniform when adding alloy; After the composition and temperature of the molten steel are uniform, start the weak blowing mode and the soft blowing mode in sequence to make the inclusions in the molten steel float up.

8. The method for increasing the number of continuous casting furnaces for bloom bearing steel by RH vacuum refining according to claim 1, characterized in that: The RH vacuum process includes: Configure the material of the vacuum tank in the RH vacuum process, the temperature of the molten steel in the tank, the high vacuum holding time during the tank washing process, and the circulation gas flow rate during the high vacuum process; Control the argon blowing intensity in the RH vacuum process and use the slag surface insulation to cover the molten steel with the refined final slag target; During the RH vacuum process, after the impregnated pipe is sprayed, the impregnated pipe is baked.

9. The method for increasing the number of continuous casting furnaces for bloom bearing steel by RH vacuum refining according to claim 1, characterized in that: The continuous casting process based on invasive open pouring and full-process protective pouring, and the method of using long shroud and argon sealing protective pouring includes: Before starting the machine, check the argon gas management and the condition of the long nozzle. After putting the sealing ring on the long nozzle and making sure it is vertical, lock the manipulator; Determine the start time of the ladle heating according to the distance between the shroud and the liquid level of the tundish; when transferring tundishes, clean the shroud from the tundish; When the tundish reaches a preset weight, a carbon-free covering agent is added to the tundish, and when the liquid surface of the tundish turns red, carbonized rice husk is added; When starting the first furnace during the pouring process, measure the temperature several times and then adjust to the preset pouring speed.

10. The method for increasing the number of continuous casting furnaces for bloom bearing steel by RH vacuum refining according to claim 9, characterized in that: When subcontracting, the cleaning of the residues from the shroud includes: When subcontracting, clean the bowl of the long nozzle of the shroud to remove the residue and steel; After cleaning the bowl of the long nozzle, clean the residual slag at the bottom of the long nozzle.

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