Intelligent determination method and system for temperature and oxygen measurement timing during RH refining of ultra-low carbon steel

Abstract

The present invention discloses a method for intelligently determining the timing of temperature measurement and oxygen determination during the RH refining process of ultra-low carbon steel. The method specifically comprises the following steps: (1) during the RH treatment process of the molten steel, sequentially determining the temperature measurement and oxygen determination times of the molten steel at the time of entering the station, during decarburization, before the end of decarburization, after oxygen supplementation before the end of decarburization, after the end of deoxidation, and before RH air breaking; and (2) issuing a temperature measurement and oxygen determination prompt after the temperature measurement and oxygen determination times are reached. The present invention provides a method for determining the temperature measurement and oxygen determination times during RH refining of ultra-low carbon steel, quantitatively determining the timing of temperature measurement and oxygen determination during RH refining of ultra-low carbon steel, improving the level of on-site standardized operations, and enhancing the accuracy of molten steel temperature and composition control.

Description

Technical Field

[0001] The present invention belongs to the technical field of iron and steel metallurgy, and more specifically, to a method and system for intelligently determining the timing of temperature measurement and oxygen determination during RH refining of ultra-low carbon steel. Background Art

[0002] The RH refining furnace is a highly efficient refining equipment with multiple refining functions, including decarburization, degassing, composition homogenization, temperature adjustment, and inclusion removal. It plays an extremely important role in the production of ultra-low carbon steel. When smelting ultra-low carbon steel in an RH refining furnace, the smelting process is divided into the decarburization period, deoxidation period, alloying period, and molten steel clean circulation period, according to the time progression. The main purpose of the decarburization period is to decarburize and control the oxygen content and temperature of the molten steel before the end of decarburization. Control methods include adding carbon powder, cooling cold materials, and blowing oxygen. This period is the main time window for controlling the oxygen content and temperature of the molten steel before the end of decarburization. The deoxidation period involves adding aluminum-containing materials to the molten steel to remove excess oxygen, while simultaneously releasing heat to compensate for the temperature. The main purpose of the alloying period is to adjust the chemical composition of the molten steel. The purpose of the molten steel clean circulation period is to uniform the temperature and composition of the molten steel and remove inclusions.

[0003] When smelting ultra-low carbon steel in an RH refining furnace, molten steel temperature and oxygen content are crucial technical parameters. The molten steel temperature must meet the requirements for smooth continuous casting. Excessively high temperatures can easily lead to production quality issues such as breakouts and bulging of the ingots, while excessively low temperatures can cause ingot stagnation. Furthermore, to ensure the cleanliness of the ingots, chemical heating is prohibited during the later stages of RH treatment. The oxygen content of the molten steel must meet the requirements for decarburization of the ultra-low carbon steel. If the temperature is insufficient, a compensation temperature must be reserved for the exothermic reaction between oxygen and aluminum. Therefore, during the RH treatment process, changes in these two parameters must be closely monitored. These parameters are measured by a temperature and oxygen measurement system. During the RH smelting process, the temperature and oxygen measurement lances attached to the temperature and oxygen measurement system are repeatedly inserted into the molten steel by humans or by temperature measurement robots. The temperature and oxygen content of the molten steel are simultaneously measured, and subsequent operations are adjusted accordingly. When the oxygen content is insufficient for decarburization, oxygen is blown through the RH top lance. When the oxygen content exceeds the decarburization and excess oxygen requirements, aluminum pellets or a recarburizer are added for pre-deoxidation. When the molten steel temperature is insufficient, oxygen is blown and the temperature is compensated by subsequent aluminum additions. When the molten steel temperature is high, cooling is performed by adding cold material. Furthermore, since the temperature measurement probe also has an aluminum determination function, the amount of aluminum-containing material to be added is determined based on the aluminum determination results. Clearly, the specific timing of temperature and oxygen measurement is crucial.

[0004] The scientific paper "Process Improvement for Cold-Rolled Ultra-Low Carbon Steel by RH Processing" (China Metallurgy, 2010, Issue 7, p. 36) discusses the timing of temperature and oxygen measurement during RH smelting of ultra-low carbon steel: When the carbon monoxide mass fraction detected by the exhaust gas analyzer drops to 20%, an ultra-low carbon sample is measured for temperature and oxygen measurement. When the carbon monoxide mass fraction detected by the exhaust gas analyzer drops to 10%, temperature and oxygen measurement are performed. Based on the measured oxygen value, the amount of aluminum to be added is calculated to deoxidize the molten steel and control the aluminum content to the target value. The main idea is to determine the timing of temperature and oxygen measurement based on the CO content of the exhaust gas analyzed by a mass spectrometer in the RH exhaust gas pipeline. However, the problem is that this only mentions the timing of temperature and oxygen measurement at the decarburization endpoint. In reality, during the RH smelting of ultra-low carbon steel, multiple measurements of molten steel temperature and oxygen content are required to adjust subsequent operations. Furthermore, this requires expensive mass spectrometers, which many steel mills do not yet have. Summary of the Invention

[0005] The present invention provides a method for intelligently determining the timing of temperature measurement and oxygen determination during RH refining of ultra-low carbon steel, which automatically determines the timing of temperature measurement and oxygen determination during the entire RH treatment cycle.

[0006] The present invention is achieved by providing a method for intelligently determining the timing of temperature and oxygen measurement during RH refining of ultra-low carbon steel, characterized in that the method specifically comprises the following steps:

[0007] (1) During the RH treatment of molten steel, the temperature and oxygen measurement times of the molten steel are determined in sequence: when the molten steel enters the station, during the decarburization process, before the end of decarburization, after oxygenation before the end of decarburization, after the end of deoxidation, and before RH breaking;

[0008] (2) After the temperature and oxygen measurement time is reached, a temperature and oxygen measurement prompt will be issued.

[0009] Furthermore, the temperature and oxygen measurement time when entering the station is:

[0010] After the molten steel enters the RH treatment station, it starts to be lifted. When the lifting height of the ladle trolley meets the on-site temperature measurement height, the lifting of the ladle trolley is stopped and the temperature and oxygen are measured.

[0011] Furthermore, the temperature and oxygen measurement time during the decarburization process is:

[0012] If no deoxidizing carbon powder, oxygen blowing, or cold material is added according to the temperature and oxygen determination results when the molten steel enters the station, the temperature and oxygen determination shall be carried out after the set time I from the moment when the RH starts to vacuum;

[0013] If at least one of the following operations, namely, adding deoxidized carbon powder, blowing oxygen, or adding cold material, is required based on the results of temperature and oxygen measurement when the molten steel enters the station, the temperature and oxygen measurement shall be carried out after the following conditions are met:

[0014] Condition (1): Set duration II after the last operation is completed;

[0015] Condition (2): set time length I from the moment when RH starts to evacuate;

[0016] The set time I is the time required for the temperature drop of the ladle and the vacuum tank to stabilize and oxygen evolution to be sufficient, and the set time II is the time required for the chemical reaction and mixing of the added substances with the molten steel.

[0017] Furthermore, the temperature and oxygen measurement time before the end of decarburization is:

[0018] If, based on the results of temperature and oxygen measurement during the decarburization process, any of the following operations, such as adding deoxidized carbon powder, blowing oxygen, or adding cold material, is required, the temperature and oxygen measurement should be performed after the following conditions are met:

[0019] Condition (1): Set duration II after the last operation is completed;

[0020] Condition (2): High vacuum cumulative time ≥ A minutes, where A is set based on the vacuum pump's exhaust capacity, the amount of molten steel, and the target carbon content at the end of RH treatment;

[0021] If, according to the results of temperature and oxygen determination during the decarburization process, there is no need to add deoxidized carbon powder, blow oxygen, or add cold material, then temperature and oxygen determination should be carried out after the accumulated high vacuum time is ≥A minutes.

[0022] Furthermore, the temperature measurement and oxygen determination time after oxygen supplementation before the end of decarburization is:

[0023] Whether oxygen supplementation is needed is determined based on the results of temperature and oxygen determination before the end of decarburization. If oxygen supplementation is needed, temperature and oxygen determination will be performed after the set time II after the end of oxygen blowing.

[0024] Furthermore, the method for detecting whether oxygen supplementation is required before the end of decarburization is as follows:

[0025] (1) If the oxygen content obtained by temperature measurement and oxygen determination before the end of decarburization is less than the target oxygen content at the end of decarburization, oxygen supplementation is required before the end of decarburization;

[0026] (2) Calculate whether it is necessary to blow oxygen to compensate the temperature before the end of decarburization based on the temperature measurement and oxygen determination results before the end of decarburization. If the molten steel temperature at the time of temperature measurement and oxygen determination before the end of decarburization + the oxygen content of the molten steel at the time of temperature measurement and oxygen determination before the end of decarburization / 25 - the natural temperature drop of the molten steel from the time of temperature measurement and oxygen determination before the end of decarburization to the time of RH breaking - the temperature drop of the alloyed alloy is less than the RH breaking target temperature, then oxygen supplementation is required before the end of decarburization.

[0027] Furthermore, the temperature measurement and oxygen determination time after deoxygenation is:

[0028] The temperature and oxygen are measured and determined for a set time III after the aluminum-containing material is added, wherein the set time III is the reaction and homogenization time of the aluminum-containing material.

[0029] Furthermore, the prompt temperature measurement and oxygen determination time before RH breaks through is:

[0030] After the alloy is added during the alloying process, the temperature and oxygen are measured for a set period of time IV;

[0031] The setting time IV is set based on the net circulation time, and the temperature and oxygen are measured before the RH breaks through the air.

[0032] The present invention is achieved by providing an intelligent determination system for temperature and oxygen measurement timing during RH refining of ultra-low carbon steel, the system comprising: a temperature and oxygen measurement instrument for measuring temperature and oxygen, the output end of which is connected to the input end of a control unit, the output end of the control unit being connected to the input end of a prompt unit;

[0033] After the addition of carbon powder, oxygen, cold material, aluminum-containing material and alloy, the control unit reads the relevant signals and calculates the temperature and oxygen measurement time of the ultra-low carbon steel liquid when entering the station, during decarburization, before the end of decarburization, after oxygen supplementation before the end of decarburization, after the end of deoxidation, and before RH breaking based on the above-mentioned intelligent determination method of the temperature measurement and oxygen measurement timing of ultra-low carbon steel in the RH refining process. After the smelting time reaches the calculated temperature and oxygen measurement time, the control prompt unit issues a temperature and oxygen measurement prompt, and the temperature and oxygen measurement instrument measures the temperature and oxygen according to the prompt and uploads the temperature and oxygen measurement results to the control unit.

[0034] Furthermore, the system further comprises:

[0035] a display unit, wherein an input end is connected to an output end of the control unit, and an input end of the control unit is connected to an output end of the input unit;

[0036] After the temperature and oxygen measuring instrument uploads each temperature and oxygen measurement result to the control unit, the control unit displays it through the display unit;

[0037] The input unit receives the input temperature measurement and oxygen determination instruction, and the control unit controls the prompt unit to issue a temperature measurement and oxygen determination prompt, so that the operator can measure the temperature and oxygen determination again.

[0038] This invention provides an intelligent method for determining the timing of temperature and oxygen measurement during the RH refining furnace smelting of ultra-low carbon steel. This method can quantitatively determine the timing of temperature and oxygen measurement during the RH refining process, improving on-site standardized operations and enhancing the accuracy of molten steel temperature and composition control. Using the temperature and oxygen measurement method provided by this invention, the RH air-break temperature compliance rate reached 98.5%, and the internal control pass rate for molten steel carbon content reached 99.2%. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A flow chart of a method for intelligently determining the timing of temperature and oxygen measurement during RH refining of ultra-low carbon steel provided by an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of the structure of an intelligent system for determining the timing of temperature and oxygen measurement during RH refining of ultra-low carbon steel provided by an embodiment of the present invention;

[0041] Figure 3 This is an interface diagram of the temperature measurement and oxygen determination system during the RH refining process of ultra-low carbon steel provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The specific implementation methods of the present invention will be further explained in detail below by describing the embodiments with reference to the accompanying drawings, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0043] The chemical composition of the ultra-low carbon steel mentioned in the present invention is shown in the following table, with the remainder being iron and impurities.

[0044]

[0045] In order to control the carbon content of molten steel to meet the requirements, the target oxygen content at the end of decarburization is: 100-800ppm.

[0046] Figure 1 A flow chart of a method for measuring temperature and determining oxygen in the RH refining process of low-carbon steel provided in an embodiment of the present invention, the method specifically comprising the following steps:

[0047] (1) Temperature and oxygen measurement when entering the station

[0048] After the molten steel enters the RH treatment station, jacking begins. When the jacking height of the ladle trolley meets the on-site temperature measurement height (for example, 1500mm), the jacking of the ladle trolley is stopped and the first temperature and oxygen measurement (i.e., the molten steel temperature and oxygen content) is carried out. Based on the first temperature and oxygen measurement results, the carbon content at the end of decarburization, the RH breaking temperature and other parameters, it is calculated whether to add deoxidizing carbon powder, blow oxygen (for compensating the molten steel temperature or decarburization) and add cold material (for cooling).

[0049] (2) Temperature and oxygen measurement during decarburization

[0050] RH starts to evacuate and decarburize the molten steel. If no deoxidizing carbon powder, oxygen blowing, or cold material is added according to the temperature and oxygen determination results at the time of entering the station, a second temperature and oxygen determination is performed after the set time I from the moment when RH starts to evacuate. The set time I is set to the time required for the temperature drop of the ladle and the vacuum tank to stabilize and for oxygen evolution to be sufficient, for example, 4 to 6 minutes.

[0051] After RH starts to evacuate, decarburization of molten steel begins. If any of the following operations, such as adding deoxidizing carbon powder, blowing oxygen, or adding cold material, is required based on the temperature and oxygen measurement results at the time of entering the station, a second temperature and oxygen measurement is performed after the following conditions are met:

[0052] Condition (1): Set duration II after the last operation is completed;

[0053] Condition (2): set time length I from the moment when RH starts to evacuate;

[0054] Among them, the setting time II is the time required for the chemical reaction and mixing of the substance added to the molten steel with the molten steel, for example, 2 minutes. According to the second temperature and oxygen measurement results, it is determined whether to add deoxidizing carbon powder, blow oxygen and add cold material before the end of decarburization.

[0055] Since the temperature drop rate of the ladle and vacuum tank fluctuates greatly in the early stage, and the oxygen transfer from the vacuum tank to the molten steel is unstable, if the second temperature and oxygen measurement is carried out too early, the influence of the state of the ladle and vacuum tank on the temperature and oxygen content of the molten steel has not been eliminated. 4 to 6 minutes after the RH pumping starts, the influence of the state of the ladle and vacuum tank on the temperature and oxygen content of the molten steel is basically eliminated. After that, the temperature drop of the molten steel is basically stable, and the ladle and vacuum tank no longer release oxygen into the molten steel. Therefore, the temperature and oxygen content measured 4 to 6 minutes after the RH pumping starts have a strong guiding role in subsequent operations. The reason for delaying the temperature and oxygen measurement by 2 minutes after the completion of the last operation is that after adding carbon powder, blowing oxygen, or adding cold materials, the added materials have a certain reaction time with the molten steel. If the temperature and oxygen measurement operation is carried out immediately after the operation is completed, the measured results will be biased, which will mislead subsequent operations.

[0056] (3) Temperature and oxygen measurement before the end of decarburization;

[0057] If any of the following operations, such as adding deoxidized carbon powder, blowing oxygen, or adding cold material, is required based on the results of temperature and oxygen measurement during the decarburization process, the third temperature and oxygen measurement should be performed after the following conditions are met:

[0058] Condition (1): Set duration II after the last operation is completed;

[0059] Condition (2): The cumulative time of high vacuum (vacuum degree ≤ 200 Pa) is ≥ A minutes, where A is related to the vacuum pump's exhaust capacity, the amount of molten steel, and the target carbon content at the end of RH treatment.

[0060] If the results of temperature and oxygen measurement during the decarburization process show that there is no need to add deoxidized carbon powder, blow oxygen, or add cold material, then the third temperature and oxygen measurement should be carried out after the cumulative time of high vacuum (vacuum degree ≤ 200 Pa) is ≥ A minutes.

[0061] Based on the third temperature and oxygen measurement results, it is detected whether oxygen supplementation is needed before the end of decarburization. The detection method is as follows:

[0062] (1) If the oxygen content of the third temperature-controlled oxygen measurement is less than the target oxygen content at the end of decarburization, oxygen supplementation, i.e. oxygen blowing, is required before the end of decarburization. The purpose is to ensure that the oxygen content at the end of decarburization meets the requirements, and the ultimate goal is to ensure that the RH carbon content is qualified.

[0063] (2) Based on the third temperature and oxygen measurement result, calculate whether oxygen blowing is required to compensate for the temperature before decarburization is completed. If: the molten steel temperature at the third temperature and oxygen measurement + the molten steel oxygen content at the third temperature and oxygen measurement / 25 - the natural temperature drop of the molten steel from the third temperature and oxygen measurement to the RH break-through time - the alloying alloy temperature drop < the RH break-through target temperature, then oxygen supplementation, i.e., oxygen blowing, is required before the end of decarburization to ensure that the molten steel temperature at the RH break-through time reaches the target temperature. Among them, 25 is the deoxidation heating constant, i.e., the oxygen content (ppm) required for the molten steel to rise by 1°C.

[0064] (4) Temperature measurement and oxygen determination after oxygen supplementation before the end of decarburization

[0065] If oxygen needs to be supplemented based on the results of temperature and oxygen determination before the end of decarburization, the fourth temperature and oxygen determination will be performed for the set time II after the oxygen blowing is completed. If oxygen supplementation is not required before the end of decarburization, the fourth temperature and oxygen determination is not required. The amount of aluminum-containing material to be added is calculated based on the oxygen content of the third or fourth temperature and oxygen determination and the target Als. (5) Temperature and oxygen determination after deoxidation

[0066] After the aluminum-containing material is added, the fifth temperature and oxygen measurement is performed at set time III, and the AlS content in the molten steel is tested. Set time III is the reaction and homogenization time for the aluminum-containing material. If the temperature and oxygen measurement is performed too early, the measured oxygen content will be inaccurate and unrepresentative, misleading subsequent operations. If the temperature and oxygen measurement is performed too late, the RH treatment time will be extended.

[0067] The purpose of oxygen determination here is to indirectly obtain the Als content of molten steel through oxygen determination. If the Als content is lower than the target Als, aluminum-containing materials need to be added during alloying.

[0068] (6) Temperature and oxygen measurement before RH breaks

[0069] After the alloy or aluminum-containing material is added during the alloying process, the sixth temperature and oxygen measurement is performed at set time IV. Set time IV is set based on the net cycle time requirement. After the alloy is added, a certain net cycle time must be guaranteed before breaking through the air and ending the RH treatment. The net cycle time required for each steel grade is specified in the operation document and is related to the steel grade. The purpose of setting the lower limit of the net cycle time is to ensure the effect of removing inclusions in the molten steel and improve the purity of the molten steel. Since the temperature and oxygen measurement operation requires a certain amount of preparation time (about 1 minute), if the temperature and oxygen are not measured until the net cycle time reaches the required net cycle time, the RH treatment time will be extended. Therefore, the "set time IV" is designed, and the set time IV is less than the net cycle time required by the operation instructions. Assuming that the net cycle time requirement is ≥6 minutes, set time IV can be set to 5 minutes.

[0070] Figure 2A schematic diagram of the structure of a temperature measurement and oxygen determination system for low-carbon steel in the RH refining process provided by an embodiment of the present invention. For ease of illustration, only the parts related to the embodiment of the present invention are shown. The system includes:

[0071] A temperature and oxygen measuring instrument for measuring temperature and determining oxygen, wherein the output end is connected to the input end of the control unit, the output end of the control unit is connected to the input end of the prompt unit, and the prompt unit is arranged in the control room;

[0072] After the addition of carbon powder, oxygen, cold material and alloyed aluminum-containing material is completed, the control unit reads the relevant signals and calculates the temperature and oxygen determination time of the low-carbon steel molten steel when entering the station, during decarburization, before the end of decarburization, after oxygen replenishment before the end of decarburization, after the end of deoxidation, and before RH breaking based on the above-mentioned temperature measurement and oxygen determination method of low-carbon steel in the RH refining process. After the smelting time reaches the temperature and oxygen determination time, the control prompt unit issues a temperature and oxygen determination prompt, and the operator or the temperature measurement and sampling robot performs temperature and oxygen determination based on the temperature and oxygen measurement prompt, and the temperature and oxygen measurement instrument uploads the temperature and oxygen measurement results to the control unit.

[0073] In an embodiment of the present invention, the system further includes:

[0074] a display unit, wherein an input end is connected to an output end of the control unit, and an input end of the control unit is connected to an output end of the input unit;

[0075] After the temperature measuring and oxygen determination instrument uploads the temperature measuring and oxygen determination results to the control unit, the control unit displays them through the display unit; if the current temperature measuring and oxygen determination results are found to be abnormal, a temperature measuring and oxygen determination instruction can be input through the input unit. After the input unit receives the manually input temperature measuring and oxygen determination instruction, the control unit controls the prompt unit to issue a temperature measuring and oxygen determination prompt again, so that the operator can perform the temperature measuring and oxygen determination operation again.

[0076] In order to further illustrate the concept of the present invention, the present invention will be further described below by taking the smelting of ultra-low carbon steel in a 300TRH refining furnace as an example.

[0077] Example 1: Ultra-low carbon steel, brand: DC04 automotive plate. The chemical composition of the ultra-low carbon steel is shown in the table below, with the remainder being iron and impurities.

[0078]

[0079]

[0080] The target oxygen for decarburization of this steel is 300ppm, and the target air breaking temperature is 1580℃.

[0081] The primary molten steel smelted in the converter enters the RH furnace treatment position. The carbon content of the molten steel when entering the RH station is: 415ppm;

[0082] Determination of the time for the first temperature and oxygen measurement: After the molten steel enters the RH treatment station, it starts to be lifted. When the lifting height of the ladle trolley meets the on-site temperature measurement height condition, the lifting of the ladle trolley is stopped and the first temperature and oxygen measurement is carried out. The measured molten steel temperature T1: 1642℃, [O]1: 627ppm. According to general metallurgical knowledge, it is known that oxygen blowing of 115Nm is required during the decarburization process. 3 , add 1200kg of cooling material, no need to add deoxidized carbon powder. After RH vacuuming, blow oxygen 115Nm 3 , add 1200kg of cooling material, and the time for adding cooling material to end is 5 minutes after the start of treatment;

[0083] Determination of the time for the second temperature measurement and oxygen determination: Since the oxygen blowing and cooling cold material addition operations were carried out according to the first temperature measurement and oxygen determination, and the last cooling cold material addition operation ended 5 minutes after the start of the treatment, the time of completion of this operation + 2 minutes. That is, the second temperature measurement and oxygen determination is carried out 7 minutes after the start of the treatment. The measured molten steel temperature T2: 1610℃, [O]2: 342ppm. According to general knowledge of metallurgy, it is known that 600kg of cooling cold material needs to be added. After the second temperature measurement and oxygen determination, 600kg of cooling cold material is added, and the cooling cold material addition ends 10 minutes after the start of the treatment.

[0084] Determination of the third temperature and oxygen measurement time:

[0085] Condition 1: According to the second temperature and oxygen measurement results, it is not necessary to add deoxidized carbon powder, so this condition is considered to be met;

[0086] Condition 2: According to the second temperature and oxygen measurement results, the time when 600 kg of cold material is added is calculated to be 11 minutes from the start of the pumping. Therefore, condition 2 is met when the time is 13 minutes from the start of the pumping.

[0087] Condition 3: According to the second temperature measurement and oxygen determination results, oxygen blowing is not required, so this condition is considered to be met;

[0088] Condition 4: For this steel grade, the carbon content meets the RH requirement if the cumulative high vacuum (vacuum degree ≤ 200 Pa) time is ≥ 7 minutes. During production, the cumulative high vacuum (vacuum degree ≤ 200 Pa) time reaches 7 minutes 12 minutes after the start of the pumping operation. Therefore, this condition is considered to be met 12 minutes after the start of the pumping operation.

[0089] In summary, the conditions for the third temperature and oxygen measurement were met 13 minutes after the start of extraction, and the measured molten steel temperature T3 was 1597°C and [O]3 was 315ppm.

[0090] Determination of the time for the fourth temperature and oxygen measurement:

[0091] According to the results of the third temperature measurement and oxygen determination, since the [O]3 measured for the third time is 315ppm, which is greater than the target oxygen content at the end of decarburization (300ppm), no oxygen blowing operation (oxygen supplementation) is performed; since "the molten steel temperature measured during the third temperature measurement and oxygen determination + the molten steel oxygen content during the third temperature measurement and oxygen determination / 25 - the natural temperature drop of the molten steel from the time of the third temperature measurement and oxygen determination to the time of RH breaking through - the temperature drop of the alloyed alloy = 1597 + 315 / 25 - 17 - 2 = 1584°C, which is greater than the target RH breaking through temperature (1580°C)", no oxygen blowing operation (oxygen supplementation) is required, so there is no need to perform the fourth temperature measurement and oxygen determination.

[0092] Determination of the time for the fifth temperature and oxygen measurement: The amount of aluminum-containing material to be added for deoxidation alloying is calculated based on the oxygen content obtained from the third temperature and oxygen measurement and the target Als. 450 kg of aluminum-containing material needs to be added. The addition of 450 kg of aluminum-containing material is completed 16 minutes after the start of pumping. The fifth temperature and oxygen measurement is performed 2 minutes after the addition, that is, 18 minutes after the start of pumping. The measured molten steel temperature T5 is 1589°C, [O]5 is 2.74 ppm, and Als content is 0.052%. No additional aluminum-containing material is required.

[0093] Determination of the time for the sixth temperature and oxygen measurement: After the fifth temperature and oxygen measurement, the alloying alloy was added. The alloy addition ended 21 minutes after the start of the pumping operation. Five minutes later, or 26 minutes after the start of the pumping operation, the sixth temperature and oxygen measurement was performed. The measured molten steel temperature T6 was 1581°C, and [O]6 was 2.65 ppm.

[0094] Example 2: Ultra-low carbon steel, brand: automotive plate MBTP125001. The chemical composition of the ultra-low carbon steel is shown in the table below, with the remainder being iron and impurities.

[0095]

[0096] The target oxygen content for the decarburization of this steel is 250ppm, and the target air breaking temperature is 1579℃.

[0097] The primary molten steel smelted in the converter enters the RH furnace treatment position. The carbon content of the molten steel when entering the RH station is: 323ppm;

[0098] Determination of the first temperature and oxygen measurement time: After the molten steel enters the RH treatment station, it begins to be lifted. When the ladle trolley's lifting height meets the on-site temperature measurement height requirements, the lifting of the ladle trolley is stopped and the first temperature and oxygen measurement is performed. The measured molten steel temperature T1: 1636°C, [O]1: 420ppm. According to general metallurgical knowledge, oxygen blowing is not required during the decarburization process. 568kg of cooling material is added, and deoxidizing carbon powder is not required. After RH vacuuming, 568kg of cooling material is added. The cooling material addition ends 4.8 minutes after the start of the treatment.

[0099] Determination of the time for the second temperature measurement and oxygen determination: Since the cooling operation was carried out based on the first temperature measurement and oxygen determination, and the cooling operation ended 4.8 minutes after the start of the process, the second temperature measurement and oxygen determination was carried out 6.8 minutes after the start of the process. The measured molten steel temperature T2: 1603℃, [O]2: 161ppm, according to general metallurgical knowledge, it is known that 30Nm of oxygen blowing is required. 3 After the second temperature measurement and oxygen determination, blow oxygen at 30Nm 3 The oxygen blowing ends 9 minutes after the treatment starts;

[0100] Determination of the third temperature and oxygen measurement time:

[0101] Condition 1: According to the second temperature and oxygen measurement results, it is not necessary to add deoxidized carbon powder, so this condition is considered to be met;

[0102] Condition 2: According to the second temperature and oxygen measurement results, it is calculated that no cold material is needed, so this condition is considered to be met;

[0103] Condition 3: According to the second temperature measurement and oxygen determination results, it is calculated that 30Nm of oxygen is needed. 3 , the oxygen blowing end time is 9 minutes after the start time of treatment, so it is considered that this condition is met 11 minutes after the start time of treatment;

[0104] Condition 4: For this steel grade, the carbon content meets the RH requirement if the cumulative high vacuum (vacuum degree ≤ 200 Pa) time is ≥ 7 minutes. During production, the cumulative high vacuum (vacuum degree ≤ 200 Pa) time reaches 7 minutes 12 minutes after the start of the pumping operation. Therefore, this condition is considered to be met 12 minutes after the start of the pumping operation.

[0105] In summary, the conditions for the third temperature and oxygen measurement were met 12 minutes after the start of extraction, and the measured molten steel temperature T3 was 1594°C and [O]3 was 230ppm.

[0106] Determination of the fourth temperature and oxygen measurement time:

[0107] According to the results of the third temperature measurement and oxygen determination, since the [O]3 measured for the third time is 230ppm, which is less than the target oxygen content at the end of decarburization (250ppm), oxygen blowing operation (oxygen supplementation) is required; since "the temperature of the molten steel measured during the third temperature measurement and oxygen determination + the oxygen content of the molten steel during the third temperature measurement and oxygen determination / 25-the natural temperature drop of the molten steel from the time of the third temperature measurement and oxygen determination to the time of RH breaking through air-the temperature drop of the alloyed alloy = 1594+230 / 25-17.8-4=1581.4℃, > the target temperature of RH breaking through air (1579℃)", oxygen blowing operation (temperature increase) is not required. After comprehensive consideration, according to the results of the third temperature measurement and oxygen determination, oxygen blowing is required. The end time of oxygen blowing is 14.5 minutes after the start time of treatment, so the fourth temperature measurement and oxygen determination is carried out at the completion time of oxygen blowing operation + 2 minutes, that is, 16.5 minutes after the start time of treatment.

[0108] Determination of the time for the fifth temperature and oxygen measurement: The amount of aluminum-containing material to be added for deoxidation alloying is calculated based on the oxygen content obtained from the fourth temperature and oxygen measurement and the target Als. 310 kg of aluminum-containing material needs to be added. The addition of 310 kg of aluminum-containing material ends 18 minutes after the start of pumping. The fifth temperature and oxygen measurement is performed 2 minutes after the addition, that is, 20 minutes after the start of pumping. The measured molten steel temperature T5 is 1594°C, [O]5 is 2.69 ppm, and Als content is 0.050%. No additional aluminum-containing material is required.

[0109] Determination of the time for the sixth temperature and oxygen measurement: After the fifth temperature and oxygen measurement, the alloyed alloy was added. The alloy addition ended 24 minutes after the start of the pumping operation. Five minutes later, or 29 minutes after the start of the pumping operation, the sixth temperature and oxygen measurement was performed. The measured molten steel temperature T6 was 1580°C, and [O]6 was 2.71 ppm.

[0110] The present invention has been described exemplarily. Obviously, the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the scope of protection of the present invention.

Claims

1. A method for intelligently determining the timing of temperature and oxygen measurement during RH refining of ultra-low carbon steel, characterized in that: The method specifically comprises the following steps: (1) During the RH treatment of molten steel, the temperature and oxygen measurement times of the molten steel are determined in sequence: when the molten steel enters the station, during the decarburization process, before the end of decarburization, after oxygenation before the end of decarburization, after the end of deoxidation, and before RH breaking; (2) After the temperature and oxygen measurement time is reached, a temperature and oxygen measurement prompt is issued; Among them, the temperature and oxygen measurement time during the decarburization process is: If no deoxidizing carbon powder, oxygen blowing, or cold material is added according to the temperature and oxygen determination results when the molten steel enters the station, the temperature and oxygen determination shall be carried out after the set time I from the moment when the RH starts to vacuum; If at least one of the following operations, namely, adding deoxidized carbon powder, blowing oxygen, or adding cold material, is required based on the results of temperature and oxygen measurement when the molten steel enters the station, the temperature and oxygen measurement shall be carried out after the following conditions are met: Condition (1): Set duration II after the last operation is completed; Condition (2): set time length I from the moment when RH starts to evacuate; Set time Ⅰ as the time required for the temperature drop of the ladle and vacuum tank to stabilize and oxygen evolution to be sufficient, and set time Ⅱ as the time required for the chemical reaction and mixing of the added substances with the molten steel; Among them, the temperature and oxygen measurement time before the end of decarburization is: If, based on the results of temperature and oxygen measurement during the decarburization process, any of the following operations, such as adding deoxidized carbon powder, blowing oxygen, or adding cold material, is required, the temperature and oxygen measurement should be performed after the following conditions are met: Condition (1): Set duration II after the last operation is completed; Condition (2): High vacuum cumulative time ≥ A minutes, where A is set based on the vacuum pump's exhaust capacity, the amount of molten steel, and the target carbon content at the end of RH treatment; If, according to the results of temperature and oxygen determination during the decarburization process, it is not necessary to add deoxidized carbon powder, blow oxygen, or add cold material, then temperature and oxygen determination should be performed after the high vacuum cumulative time is ≥ A minutes; Among them, the temperature measurement and oxygen determination time after oxygen supplementation before the end of decarburization is: Whether oxygen supplementation is needed is determined based on the results of temperature and oxygen determination before the end of decarburization. If oxygen supplementation is needed, temperature and oxygen determination will be performed after the set time II after the end of oxygen blowing.

2. The method for intelligently determining the timing of temperature and oxygen measurement during RH refining of ultra-low carbon steel according to claim 1, characterized in that: The time for temperature measurement and oxygen determination when entering the station is: After the molten steel enters the RH treatment station, it starts to be lifted. When the lifting height of the ladle trolley meets the on-site temperature measurement height, the lifting of the ladle trolley is stopped and the temperature and oxygen are measured.

3. The method for intelligently determining the timing of temperature and oxygen measurement during RH refining of ultra-low carbon steel according to claim 2, characterized in that: The specific method for detecting whether oxygen supplementation is required before the end of decarburization is as follows: (1) If the oxygen content obtained by temperature measurement and oxygen determination before the end of decarburization is less than the target oxygen content at the end of decarburization, oxygen supplementation is required before the end of decarburization; (2) Calculate whether it is necessary to blow oxygen to compensate for the temperature before the end of decarburization based on the results of temperature measurement and oxygen determination before the end of decarburization. If the molten steel temperature at the time of temperature measurement and oxygen determination before the end of decarburization + the oxygen content of the molten steel at the time of temperature measurement and oxygen determination before the end of decarburization / 25-the natural temperature drop of the molten steel from the time of temperature measurement and oxygen determination before the end of decarburization to the time of RH breaking through air-the temperature drop of the alloyed alloy is less than the target temperature of RH breaking through air, then oxygen supplementation is required before the end of decarburization. The unit of temperature is ℃, and the unit of oxygen content obtained by temperature measurement and oxygen determination before the end of decarburization is ppm.

4. The method for intelligently determining the timing of temperature and oxygen measurement during RH refining of ultra-low carbon steel according to claim 3, characterized in that: The temperature measurement and oxygen determination time after deoxygenation is: The temperature and oxygen are measured and determined for a set time III after the aluminum-containing material is added, wherein the set time III is the reaction and homogenization time of the aluminum-containing material.

5. The method for intelligently determining the timing of temperature and oxygen measurement during RH refining of ultra-low carbon steel according to claim 4, characterized in that: The prompt temperature and oxygen measurement time before RH breaks through the air is: Temperature and oxygen are measured at a set time IV after the alloy is added during the alloying process; The set duration IV is set based on the net cycle duration.

6. An intelligent system for determining the timing of temperature and oxygen measurement during RH refining of ultra-low carbon steel, characterized in that: The system comprises: a temperature and oxygen measuring instrument for measuring temperature and determining oxygen, wherein the output end of the temperature and oxygen measuring instrument is connected to the input end of the control unit, and the output end of the control unit is connected to the input end of the prompt unit; After the addition of carbon powder, oxygen, cold material, aluminum-containing material and alloy, the control unit reads the relevant signals and calculates the temperature and oxygen measurement time of the ultra-low carbon steel molten steel when entering the station, during decarburization, before the end of decarburization, after oxygen replenishment before the end of decarburization, after the end of deoxidation, and before RH breaking based on the intelligent determination method of the temperature measurement and oxygen measurement timing of ultra-low carbon steel in the RH refining process as described in claim 5. After the smelting time reaches the calculated temperature and oxygen measurement time, the control prompt unit issues a temperature and oxygen measurement prompt, and the temperature and oxygen measurement instrument uploads each temperature and oxygen measurement result to the control unit.

7. The intelligent determination system for temperature and oxygen measurement timing of ultra-low carbon steel during RH refining according to claim 6, characterized in that: The system further comprises: a display unit, wherein an input end of the display unit is connected to an output end of the control unit, and an input end of the control unit is connected to an output end of the input unit; After the temperature and oxygen measuring instrument uploads each temperature and oxygen measurement result to the control unit, the control unit displays it through the display unit; The input unit receives the input temperature measurement and oxygen determination instruction, and the control unit controls the prompt unit to issue a temperature measurement and oxygen determination prompt, so that the operator can measure the temperature and oxygen determination again.

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