Low-nitrogen control process for 30MnSi high-speed wire rod

Abstract

The invention relates to the technical field of steel and iron smelting, in particular to a low-nitrogen control process for a 30MnSi high-speed wire rod, which comprises the following steps: adding scrap steel and molten iron into an electric furnace, and adding lime, fluorite, silicon-manganese alloy and silicon-iron alloy after tapping to obtain smelted molten steel; the smelted molten steel is added into an LF refining furnace, slag crust breaking is conducted, and argon is blown to the bottom of a steel ladle during heating; the argon blowing flow is adjusted in the desulfurization process; heating the smelted molten steel and feeding a pure calcium wire to obtain refined molten steel; the refined molten steel is subjected to continuous casting, and a casting blank is obtained; in the heating stage, after the temperature of each section and the in-furnace time are set according to the charging mode, a casting blank is rolled, and a wire is obtained; and carrying out air cooling treatment on the wire rod, and carrying out coiling, finishing, bundling, weighing and coil unloading on the air-cooled wire rod to obtain the 30MnSi high-speed wire rod. The argon blowing flow is adjusted in a self-adaptive mode according to the performance of the air brick, and the nitrogen increasing risk of molten steel is avoided.

Description

Technical Field

[0001] This application relates to the field of steel smelting technology, specifically to a low-nitrogen control process for 30MnSi high-speed wire rod. Background Technology

[0002] 30MnSi high-speed wire rod refers to hot-rolled wire rod produced using high-speed rolling technology. It is widely used due to its high strength, high toughness, and low relaxation, and is a common type of construction steel product. While nitrogen in the steel can achieve solid solution strengthening during the preparation of 30MnSi high-speed wire rod, excessive nitrogen will reduce the plasticity and toughness of the steel, thereby lowering product quality. Therefore, developing a low-nitrogen control method to ensure a low nitrogen content in the steel during the preparation of 30MnSi high-speed wire rod is of great significance for improving the quality of high-speed wire rod.

[0003] In the desulfurization process of LF furnace refining, argon blowing and stirring can promote the melting of alloys in the molten steel and improve the uniformity of the composition inside the molten steel. A larger argon blowing flow rate can increase the stirring rate and desulfurization effect of the molten steel, thereby improving refining efficiency; however, an excessively large argon blowing flow rate can also expose the molten steel in the LF furnace to the air, causing the molten steel to absorb nitrogen from the air, which will affect the final product quality of 30MnSi high-speed wire rod.

[0004] While existing technologies have taken into account the nitrogen increase in molten steel caused by excessive argon flow rate, they rely on exhaustive experiments to regulate the argon flow rate. However, they do not fully consider that the permeability of argon permeable bricks in different ladles is complex and dynamic. Therefore, even if the experiment obtains the optimal control flow rate, the set argon flow rate may still be inconsistent with the actual flow rate, which will cause the argon flow rate in the refining process to deviate from the preset value and the preparation effect to be poor. Summary of the Invention

[0005] In view of the above, it is necessary to provide a low-nitrogen control process for 30MnSi high-speed wire to solve the above problems.

[0006] One embodiment of this application provides a low-nitrogen control process for 30MnSi high-speed wire, the process comprising: S1: Scrap steel and molten iron are put into an electric furnace. After the steel is tapped, lime, fluorite, silicon-manganese alloy and silicon-iron alloy are added to obtain molten steel. S2: Add molten steel to the LF refining furnace to break the slag shell. During the heating process, argon gas is blown into the bottom of the ladle. The argon flow rate is adjusted during the desulfurization process. The molten steel is heated and fed with pure calcium wire to obtain refined molten steel. The specific steps for adjusting the argon blowing flow rate during the desulfurization process are as follows: S201: Based on the difference between the atmospheric pressure inside and outside the furnace at each collected moment, obtain the pressure difference data at each moment; acquire the temperature image inside the furnace at each moment and divide it evenly, and obtain the temperature sequence at each moment based on the mean temperature data of each sub-region after division; S202: Analyze the element dispersion of the temperature sequence at each moment within the preset period, and combine the distribution similarity of the threshold segmentation results of the temperature sequence to determine the degree of molten steel exposure in each period. S203: Analyze the positive and negative characteristics of the differential pressure data at each moment of each cycle and the quantity characteristics of the high-temperature sub-regions. Combined with the degree of exposed molten steel, determine the argon blowing adjustment index for each cycle. S204: Adjust the argon blowing flow rate based on the argon blowing adjustment index for each cycle; S3: The refined molten steel is continuously cast to obtain a billet; S4: During the heating stage, after setting the temperature of each section and the time in the furnace according to the furnace loading method, the billet is rolled to obtain wire. S5: The wire is air-cooled. After air-cooling, the wire is wound, finished, bundled, weighed and unwound to obtain 30MnSi high-speed wire.

[0007] Specifically, the addition of lime, fluorite, ferrosilicon, and ferrosilicon after tapping the steel is as follows: the tapping temperature is 1625-1640 degrees Celsius, and 30 seconds after tapping, lime containing 12-14 kg / t of steel and fluorite containing 3-4 kg / t of steel are added first, followed by ferrosilicon containing 12-14 kg / t of steel and ferrosilicon containing 6-8 kg / t of steel. The tapping process is carried out by argon blowing throughout, with an argon flow rate of 17-25 NL / min.

[0008] The argon flow rate for breaking the slag shell is 50-200 NL / min; the argon flow rate for bottom blowing in the ladle is 400-500 NL / min; and the argon flow rate range for the desulfurization process is 400-500 NL / min.

[0009] The specific operation of heating and feeding pure calcium wire into molten steel is as follows: the temperature of molten steel is heated to 1580℃, and the speed of feeding pure calcium wire into molten steel is controlled at 140-150 m / furnace, at which time the argon flow rate is 20-80 NL / min.

[0010] Specifically, determining the degree of molten steel exposure in each cycle involves: The degree of dispersion of the mean temperature data of all sub-regions at each time point is denoted as the temperature dispersion value. The sub-regions whose average temperature data at each time point is greater than the segmentation threshold are designated as high-temperature sub-regions. Based on the serial numbers of all high-temperature sub-regions at each time point, a regional position sequence is formed. The first mean is obtained by averaging the distance characteristics between the regional positional sequences of all adjacent times in each cycle. The negative correlation mapping result of the first mean of each cycle is positively fused with the mean of the discrete temperature values ​​at all times to obtain the steel exposure index for each cycle.

[0011] The determination of the argon blowing adjustment index for each cycle includes: Obtain the number of high-temperature sub-regions at each time point in each cycle; Calculate the similarity between the sequence of differential pressure data at all times in each period and the sequence of the quantities obtained at all times, and record it as the first correlation value for each period; Let the argon blowing regulation index for the i-th cycle be denoted as . Its formula is as follows: In the formula, The number of negative numbers in the differential pressure sequence of the i-th period; This is the first correlation value for the i-th period; It is an exponential function with the natural constant e as the base; Let be the steel exposure index for the i-th period. This indicates the preset parameters.

[0012] Specifically, adjusting the argon blowing flow rate involves: Calculate the product of the normalized value of the argon blowing adjustment index and the preset weighting coefficient, and add the product to the preset argon blowing flow rate for each cycle to obtain the adjusted argon blowing flow rate for each cycle.

[0013] The specific operation of continuous casting of refined molten steel is as follows: the molten steel is injected into the tundish of the continuous casting machine, the molten steel level is controlled at 800-900mm, and the slag layer thickness in the tundish is controlled at 70-80mm; during the continuous casting process, the crystallization electromagnetic stirring is turned on throughout, the current intensity is controlled at 300-350A, the frequency is 3-3.5Hz, the cooling water control mode adopts the weak cooling mode, and the casting speed is controlled at 2.9-3.3m / min.

[0014] Specifically, setting the temperature and furnace time for each section according to the furnace loading method includes: When the furnace is loaded in cold mode, the total time in the furnace is 70-80 minutes, the preheating zone temperature is 1040-1070℃, the heating zone temperature is 1100-1200℃, and the soaking zone temperature is 1090-1150℃. When the furnace is loaded in hot loading mode, the total time in the furnace is 60-70 minutes, the preheating zone temperature is 1050-1080℃, the heating zone temperature is 1120-1160℃, and the soaking zone temperature is 1090-1130℃.

[0015] The specific operation for rolling the billet is as follows: the initial rolling temperature is 1090-1130℃, the finishing rolling temperature is 980-1020℃, the wire drawing temperature is 860-880℃, and the rolling speed is 50-70m / s.

[0016] The beneficial effects of this application are as follows: This application monitors the pressure difference between the inside and outside of the furnace, enabling real-time understanding of pressure changes within the furnace. This is crucial for assessing atmosphere changes and furnace stability. Furthermore, acquiring temperature images and segmenting each region provides more detailed temperature distribution information, facilitating the identification of the thermal state of molten steel at different locations and providing high-precision data for subsequent analysis. This provides accurate temperature and pressure benchmarks for subsequent steel desulfurization and refining processes. Further, analyzing the dispersion of the temperature sequence reveals the amplitude of temperature fluctuations, reflecting changes in the surface state of the molten steel. Combining the distribution similarity of temperature threshold segmentation results, a steel exposure degree is constructed to more accurately determine whether the molten steel surface is exposed. This directly impacts the desulfurization effect during refining, and accurate assessment of the exposure degree provides important control basis for subsequent argon blowing adjustments. Next, analyzing the positive and negative characteristics of the pressure difference data reveals the trend of atmosphere changes within the furnace, identifying any abnormal fluctuations. Simultaneously, the quantity characteristics of high-temperature sub-regions reflect the heat distribution and local heating of the molten steel. Combined with the steel exposure degree, this provides a more scientific basis for argon blowing adjustments in each cycle. Determining the argon blowing regulation index allows for dynamic evaluation of the direction and magnitude of argon blowing flow rate adjustment, enabling more precise flow control and improving the desulfurization efficiency of molten steel. Finally, adjusting the argon blowing flow rate based on the argon blowing regulation index allows for precise control of the argon blowing process, optimizing atmosphere conditions and preventing excessive or insufficient argon flow from adversely affecting steel quality. This adjustment effectively improves steel refining, promotes the desulfurization reaction, and allows for adaptive adjustment of the argon blowing intensity based on the performance of the permeable bricks used in the actual preparation process, thereby avoiding the risk of nitrogen enrichment in the molten steel and improving the preparation quality of 30MnSi high-speed wire rod. Attached Figure Description

[0017] Figure 1 A flowchart of a low-nitrogen control process for 30MnSi high-speed wire provided in this application; Figure 2 This application provides a flowchart outlining the specific steps involved in adjusting the argon flow rate during the desulfurization process. Detailed Implementation

[0018] In the description of the embodiments in this application, the words "exemplary," "or," and "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of the words "exemplary," "or," and "for example" is intended to present the relevant concepts in a specific manner.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application's specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0020] It should also be noted that the terms "first" and "second" in this application and its accompanying drawings are used to distinguish similar objects, rather than to describe a specific order or sequence. The methods disclosed in the embodiments of this application or the methods shown in the flowcharts include one or more steps for implementing the method. Without departing from the scope of protection of this application, the execution order of multiple steps can be interchanged, and some steps can also be deleted.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0022] Example 1 Embodiment 1 of this application proposes a low-nitrogen control process for 30MnSi high-speed wire rod, which is applied in the field of steel smelting technology. (See attached figure.) Figure 1 The process includes the following steps: S1: Scrap steel and molten iron are fed into the electric furnace as raw materials. The tapping temperature is 1635℃. 30 seconds after tapping, lime containing 12 kg / t of steel and fluorite containing 3 kg / t of steel are added first, followed by silicon-manganese alloy containing 12 kg / t of steel and ferrosilicon alloy containing 6 kg / t of steel. The tapping process uses argon blowing throughout, with an argon flow rate of 20 NL / min, to obtain molten steel.

[0023] S2: Add molten steel to the LF refining furnace and break the slag shell with an argon flow rate of 150 NL / min; during the subsequent heating and temperature rise, the bottom blowing argon flow rate of the ladle is 450 NL / min; then, during the desulfurization process, the argon flow rate is 400-500 NL / min; finally, heat the molten steel to 1580℃ in the LF refining furnace, and control the feeding speed of pure calcium wire into the molten steel at 140 m / furnace, at which time the argon flow rate is 50 NL / min to ensure that the molten steel is not exposed, thereby obtaining the refined molten steel.

[0024] It should be noted that during the desulfurization process in the LF furnace refining, argon blowing and stirring can promote the melting of alloys in the molten steel and improve the uniformity of the composition inside the molten steel. A larger argon blowing flow rate can increase the stirring rate and desulfurization effect of the molten steel, thereby improving refining efficiency; however, an excessively large argon blowing flow rate can also expose the molten steel in the LF furnace to the air, causing the molten steel to absorb nitrogen from the air, which will affect the final quality of the 30MnSi high-speed wire rod.

[0025] While existing technologies have taken into account the nitrogen increase in molten steel caused by excessive argon flow rate, they rely on exhaustive experiments to regulate the argon flow rate. However, they do not fully consider that the permeability of argon permeable bricks in different ladles is complex and dynamic. Therefore, even if the experiment obtains the optimal control flow rate, the set argon flow rate may still be inconsistent with the actual flow rate, which will cause the argon flow rate in the refining process to deviate from the preset value and the preparation effect to be poor.

[0026] Based on the above description, this application analyzes the adaptive adjustment and control of argon blowing flow rate during the desulfurization stage of LF furnace steel, thereby achieving the goal of reducing the nitrogen content of molten steel without affecting steel refining efficiency. Specific steps include: S201: Based on the difference between the atmospheric pressure inside and outside the furnace at each collected moment, obtain the pressure difference data at each moment; acquire the temperature image inside the furnace at each moment and divide it evenly, and based on the temperature data of each sub-region after division, obtain the temperature sequence at each moment.

[0027] First, pressure sensors are installed on the inner and outer sides of the top of the LF furnace to collect the atmospheric pressure inside and outside the furnace. The difference between the internal and external pressures at each moment is recorded as the pressure difference data for that moment. Next, an infrared thermography camera is installed on the top of the LF furnace to collect the temperature data of the submerged arc slag layer on the surface of the molten steel during the desulfurization stage. The temperature images captured by the infrared camera at each moment are divided into 16 equal-sized sub-regions, and all sub-regions are arranged in order from left to right and then from top to bottom. The temperature values ​​of each sub-region are then arranged in the order of arrangement to construct the temperature sequence for that moment.

[0028] Data collection begins when the LF furnace enters the desulfurization stage. The interval between the collection of pressure and temperature data is 1 second, and the collection time for each cycle is 5 minutes, until the collection stops at the end of the desulfurization stage.

[0029] This application takes the i-th cycle as an example for analysis. Based on the differential pressure data collected at each time point in the i-th cycle, a differential pressure sequence for the i-th cycle is constructed in chronological order.

[0030] S202: Analyze the elemental dispersion of the temperature sequence at each moment within the preset period, and combine the distribution similarity of the threshold segmentation results of the temperature sequence to determine the degree of molten steel exposure in the corresponding period.

[0031] During the desulfurization process of molten steel, a low argon flow rate, while maintaining a slag layer covering the molten steel surface and preventing contact between the steel and air, reduces refining efficiency and affects desulfurization. Conversely, a high argon flow rate accelerates steel agitation, causing the molten steel to break through the top slag layer and become more exposed to air, increasing nitrogen content. Therefore, it is necessary to further evaluate the intensity and direction of argon flow rate adjustment based on the steel exposure situation to achieve precise argon flow rate control, ensuring both efficient 30MnSi high-speed wire rod production and improved wire rod quality.

[0032] Since there is a significant temperature difference between the slag layer and the molten steel, the temperature data collected by an infrared camera can be used to analyze the current degree of molten steel exposure and thus assess whether the argon blowing flow rate needs to be adjusted. If the molten steel is not exposed to the air, the surface temperatures captured by the infrared camera will all be slag layer temperatures, resulting in relatively consistent temperatures between different sub-regions. However, if the molten steel is exposed, it will lead to drastic temperature differences between the different sub-regions.

[0033] This application takes the u-th moment in the i-th period as an example for analysis.

[0034] The degree of dispersion among the elements within the temperature sequence at time u is calculated and denoted as the temperature dispersion value at time u. The temperature dispersion value reflects the degree of difference in temperature between sub-regions at time u; a larger value indicates a more inconsistent degree of molten steel exposure in each sub-region, thus reflecting a greater likelihood of a larger overall exposed area of ​​molten steel. In this embodiment, the dispersion is calculated using the coefficient of variation; in other embodiments, the dispersion can also be calculated using the standard deviation.

[0035] Furthermore, it is necessary to analyze whether the exposed molten steel is a continuous exposure or a momentary exposure caused by bubbles from the desulfurization process. If it is a momentary exposure, it is usually a normal process phenomenon. However, if it is a continuous exposure, it indicates that the molten steel has been exposed to air for a long time, which poses a significant risk of nitrogen increase. In this case, it is necessary to adjust the argon blowing flow rate in a timely manner to avoid the nitrogen content from affecting the quality of 30MnSi high-speed wire rod.

[0036] The elements within the temperature sequence at time u are used as input to the Otsu thresholding method. The sub-regions corresponding to elements whose temperature values ​​are greater than or equal to the segmentation threshold output by the Otsu thresholding method are denoted as high-temperature sub-regions. Since the sub-regions at each time step have been sorted in step S201, the position of each high-temperature sub-region at time u in the sorted sub-regions is obtained, and the region position sequence at time u is constructed according to the ascending position order.

[0037] If the exposure of molten steel is continuous, the position of the high-temperature sub-region will remain relatively stable over consecutive moments; conversely, if the exposure is instantaneous, the position of the high-temperature sub-region will change randomly.

[0038] The regional position sequence of each moment in the i-th cycle is obtained in the same way. Following the temporal order of data acquisition, starting from the second moment, the DTW distance between the previous moment and the current moment in the regional position sequence is calculated sequentially within the i-th cycle. The average of all DTW distances is recorded as the first average of the i-th cycle. The first average reflects the temporal stability of the exposed molten steel area in spatial location within the i-th cycle; the smaller the value, the more consistent the spatial locations of the high-temperature sub-regions at adjacent moments, thus reflecting a greater probability of continued exposed molten steel.

[0039] The negative correlation mapping result of the first mean of each cycle is positively fused with the mean of the discrete temperature values ​​at all times to obtain the steel exposure index for each cycle. In this embodiment, the steel exposure index of the i-th cycle is denoted as... Its specific formula is as follows: In the formula, The mean of the discrete temperature values ​​at all times in the i-th period; This is the first mean of the i-th period; The parameter is a preset value used to avoid a denominator of 0. It is taken from the range (0.005, 0.01). The value has little impact on the calculation and can be ignored. In this embodiment, it is taken as 0.008. Implementers can adjust the value themselves.

[0040] It should be understood that the molten steel exposure index can reflect the severity and duration of molten steel exposure in each cycle; the larger the value, the larger the exposed area and the longer the exposure duration in each cycle, which leads to a greater degree of nitrogen increase in the molten steel. At this time, it is more necessary to reduce the argon blowing flow rate in a timely manner to reduce the degree of molten steel exposure and ensure the preparation quality of 30MnSi high-speed wire rod.

[0041] S203: Analyze the positive and negative characteristics of the differential pressure data at each moment of each cycle and the quantity characteristics of the high-temperature sub-regions. Combined with the degree of molten steel exposure, determine the argon blowing adjustment index for each cycle.

[0042] Furthermore, during the desulfurization of molten steel, a slightly positive pressure atmosphere is typically maintained in the LF furnace to prevent large-scale entry of outside air into the furnace. However, due to differences in the permeability of the permeable bricks used in different ladles, the actual furnace pressure atmosphere may still fluctuate even when the same argon blowing flow rate is set. Therefore, it is necessary to analyze the current furnace atmosphere using real-time collected data on the pressure difference between the furnace interior and exterior to further assess whether the argon blowing flow rate needs to be adjusted.

[0043] If the collected LF furnace pressure differential data is positive but excessively significant, it indicates that the current argon blowing intensity is too high, which may lead to excessive stirring of the molten steel and breaching of the slag layer. Furthermore, because the LF furnace has openings such as charging holes and electrode holes at the top, air cannot be completely expelled. Therefore, there is still a risk of nitrogen accumulation due to the dissolution of nitrogen between the molten steel and the nitrogen remaining in the furnace. Conversely, if the LF furnace pressure differential data is negative, it means that the pressure inside the furnace is lower than the external pressure, and external air may be drawn into the furnace. The risk of nitrogen absorption by the molten steel is more direct, and in this case, it is necessary to increase the argon blowing flow rate promptly.

[0044] This application will still take the i-th cycle as an example for analysis.

[0045] Count the number of negative numbers in the pressure difference sequence of the i-th period. The number of negative numbers reflects the frequency of the pressure inside the LF furnace being lower than the atmospheric pressure outside the furnace in the i-th period, and thus indicates the frequency of negative pressure inside the furnace; the larger the value, the more unstable the slightly positive pressure atmosphere inside the furnace is in the i-th period, and the greater the possibility of air intake, and the greater the need to increase the argon blowing flow rate.

[0046] The number of negative numbers is only enough to assess whether there is a risk of air infiltration. Further analysis is needed to determine whether the differential pressure data may be too large, so as to determine whether the current LF furnace is in a reasonable slightly positive pressure atmosphere.

[0047] During the desulfurization stage of molten steel, if the argon blowing flow rate is reasonable, a relatively stable slightly positive pressure atmosphere should be maintained in the furnace. However, since the desulfurization reaction itself will generate bubble disturbances, the desulfurization bubbles will rise to the surface of the molten steel and break, causing instantaneous fluctuations in the pressure difference. At the same time, the surface of the molten steel will also show instantaneous and random local exposure, which is manifested as an instantaneous increase in the number of high-temperature sub-regions in the infrared temperature image. At this time, there will be a certain synchronous trend between the pressure difference data and the number of high-temperature sub-regions.

[0048] Conversely, if the argon flow rate is too high, it will cause the molten steel to be stirred too fast, which will continuously generate more bubbles. The frequent bursting of bubbles will cause the differential pressure data to fluctuate violently and frequently. However, since the exposed position of the molten steel is relatively stable and the duration is relatively long, the synchronous change trend between the number of high-temperature sub-regions and the differential pressure data will be poor.

[0049] In the i-th cycle, the number of high-temperature sub-regions at each moment is obtained, and a count sequence is constructed according to the temporal order of data acquisition. The absolute value of the correlation coefficient between the pressure difference sequence and the count sequence is calculated using a correlation coefficient algorithm and recorded as the first correlation value for the i-th cycle. The first correlation value reflects the consistency between the changes in furnace atmosphere disturbance and the exposed state of molten steel in the i-th cycle; the larger the value, the more synchronous the pressure difference fluctuation and the number of high-temperature sub-regions are in time, and the greater the possibility that the argon blowing flow rate is reasonable. The smaller the value, the greater the possibility that the argon blowing flow rate is too high, and the more necessary it is to reduce the argon blowing flow rate. In this embodiment, the Pearson correlation coefficient is used to determine the correlation coefficient; in other embodiments, the Spearman correlation coefficient can be used to calculate the correlation coefficient; in some other embodiments, the cosine similarity is used to calculate the correlation coefficient.

[0050] Construct the argon blowing regulation index for the i-th cycle Its formula is as follows: In the formula, The number of negative numbers in the differential pressure sequence of the i-th period; This is the first correlation value for the i-th period; This is an exponential function with the natural constant e as the base, used here to increase the weight; Let be the steel exposure index for the i-th period. This represents a preset parameter used to prevent the denominator from being 0; in this embodiment, the value is 0.008.

[0051] It should be understood that the argon blowing adjustment index reflects whether the argon blowing flow rate set in the i-th cycle is reasonable, and also reflects the direction and magnitude of adjustment required for the argon blowing flow rate in subsequent cycles. A larger absolute value of the argon blowing adjustment index indicates that the argon blowing flow rate set in the i-th cycle is less suitable, requiring greater adjustment in subsequent cycles to improve the quality of 30MnSi high-speed wire rod products. A positive argon blowing adjustment index indicates that a negative pressure phenomenon occurred in the furnace during the i-th cycle, requiring an increase in the argon blowing flow rate in subsequent cycles; a negative value indicates that the argon blowing flow rate was too high during the i-th cycle, requiring a decrease in the argon blowing flow rate in subsequent cycles to prevent nitrogen accumulation in the molten steel.

[0052] S204: Adjust the argon blowing flow rate based on the argon blowing adjustment index for each cycle.

[0053] In the current steel desulfurization stage, the subsequent argon blowing flow rate is adjusted by the argon blowing regulation index, as follows: Let's take the i-th cycle as an example for analysis.

[0054]

[0055] In the formula, The adjusted argon flow rate for the (i+1)th cycle; The argon blowing flow rate is preset before adjustment for the (i+1)th cycle; in this embodiment, it is set to 450 NL / min. The weighting coefficient is 30 in this embodiment to avoid excessive adjustment that could affect the stability of subsequent preparations. Implementers can adjust the weighting coefficient according to their specific circumstances. The value can be taken within the range specified in this application; This is the tanh normalization function.

[0056] In the current process for manufacturing 30MnSi high-speed wire rod, a preset argon blowing flow rate is used during the first cycle of steel desulfurization. The argon blowing adjustment index for the first cycle is then used to adjust the subsequent argon blowing flow rate. This allows for real-time dynamic adjustment of the argon blowing intensity based on the exposed state of the molten steel and the pressure difference within the furnace, reducing the risk of nitrogen accumulation in the molten steel and achieving low-nitrogen control for 30MnSi high-speed wire rod, thus improving manufacturing quality. The specific steps for adjusting the argon blowing flow rate during desulfurization are illustrated in the flowchart below. Figure 2 As shown.

[0057] S3: Molten steel is injected into the tundish of the continuous casting machine, with the molten steel level controlled at 800mm and the slag layer thickness controlled at 75mm. During the continuous casting process, the crystallization electromagnetic stirring is turned on throughout, with the current intensity controlled at 300A and the frequency at 3Hz. The cooling water control mode adopts the weak cooling mode, and the casting speed is controlled at 2.9m / min. The molten steel is continuously cast through the billet casting machine to obtain a 150mm×150mm billet.

[0058] S4: During the heating stage, the atmosphere inside the furnace in each section is strictly controlled, and the air-fuel ratio in each section is set to 0.7. When the furnace is charged in cold mode, the total time in the furnace is 70 minutes, with the preheating section temperature at 1040℃, the heating section temperature at 1100℃, and the soaking section temperature at 1090℃. When the furnace is charged in hot mode, the total time in the furnace is 60 minutes, with the preheating section temperature at 1050℃, the heating section temperature at 1120℃, and the soaking section temperature at 1090℃. During the rolling stage, the initial rolling temperature is 1100℃, the finishing rolling temperature is 1000℃, the wire drawing temperature is 870℃, and the rolling speed is 50m / s.

[0059] S5: The wire is air-cooled using the Stellmore air-cooling line. After the air-cooled wire is wound, finished, bundled, weighed and unwound, a high-strength and low-nitrogen 30MnSi high-speed wire is obtained.

[0060] Example 2 Embodiment 2 of this application proposes a low-nitrogen control process for 30MnSi high-speed wire rod, which is applied in the field of steel smelting technology. (See attached document.) Figure 1 The process includes the following steps: S1: Scrap steel and molten iron are fed into the electric furnace as raw materials. The tapping temperature is 1625℃. 30 seconds after tapping, lime containing 14 kg / t of steel and fluorite containing 4 kg / t of steel are added first, followed by silicon-manganese alloy containing 14 kg / t of steel and ferrosilicon alloy containing 8 kg / t of steel. The tapping process uses argon blowing throughout, with an argon flow rate of 17 NL / min, to obtain molten steel.

[0061] S2: Add molten steel to the LF refining furnace and break the slag shell with an argon flow rate of 50 NL / min; during the subsequent heating and temperature rise, the bottom blowing argon flow rate of the ladle is 400 NL / min; then, during the desulfurization process, the argon flow rate is 400-500 NL / min; finally, heat the molten steel to 1580℃ in the LF refining furnace, and control the feeding speed of pure calcium wire into the molten steel at 145 m / furnace, at which time the argon flow rate is 20 NL / min to ensure that the molten steel is not exposed, thereby obtaining the refined molten steel.

[0062] The argon flow rate during the desulfurization process was adjusted using the same method as in Example 1.

[0063] S3: Molten steel is injected into the tundish of the continuous casting machine, with the molten steel level controlled at 850mm and the slag layer thickness controlled at 70mm. During the continuous casting process, the crystallization electromagnetic stirring is turned on throughout, with the current intensity controlled at 320A and the frequency at 3.5Hz. The cooling water control mode adopts the weak cooling mode, and the casting speed is controlled at 3m / min. The molten steel is continuously cast through the billet casting machine to obtain a 150mm×150mm billet.

[0064] S4: During the heating stage, the atmosphere inside each section of the heating furnace is strictly controlled, and the air-fuel ratio in each section is set to 1. When the furnace is charged in cold mode, the total time in the furnace is 75 minutes, the preheating section temperature is 1050℃, the heating section temperature is 1150℃, and the soaking section temperature is 1100℃; when the furnace is charged in hot mode, the total time in the furnace is 65 minutes, the preheating section temperature is 1060℃, the heating section temperature is 1130℃, and the soaking section temperature is 1100℃. During the rolling stage, the initial rolling temperature is 1090℃, the finishing rolling temperature is 980℃, the wire drawing temperature is 860℃, and the rolling speed is 60m / s.

[0065] Example 3 Embodiment 3 of this application proposes a low-nitrogen control process for 30MnSi high-speed wire rod, which is applied in the field of steel smelting technology. (See attached figure.) Figure 1 The process includes the following steps: S1: Scrap steel and molten iron are fed into the electric furnace as raw materials. The tapping temperature is 1640℃. 30 seconds after tapping, lime containing 14 kg / t of steel and fluorite containing 4 kg / t of steel are added first, followed by silicon-manganese alloy containing 14 kg / t of steel and ferrosilicon alloy containing 7 kg / t of steel. The tapping process uses argon blowing throughout, with an argon flow rate of 25 NL / min, to obtain molten steel.

[0066] S2: Add molten steel to the LF refining furnace and break the slag shell with an argon flow rate of 200 NL / min; during the subsequent heating and temperature rise, the bottom blowing argon flow rate of the ladle is 500 NL / min; then, during the desulfurization process, the argon flow rate is 400-500 NL / min; finally, heat the molten steel to 1580℃ in the LF refining furnace, and control the feeding speed of pure calcium wire into the molten steel at 150 m / furnace, at which time the argon flow rate is 80 NL / min to ensure that the molten steel is not exposed, thereby obtaining the refined molten steel.

[0067] The argon flow rate during the desulfurization process was adjusted using the same method as in Example 1.

[0068] S3: Molten steel is poured into the tundish of the continuous casting machine, with the molten steel level controlled at 900mm and the slag layer thickness controlled at 75mm. During the continuous casting process, the crystallization electromagnetic stirring is turned on throughout, with the current intensity controlled at 350A and the frequency at 3.5Hz. The cooling water control mode adopts the weak cooling mode, and the casting speed is controlled at 3.3m / min. The molten steel is continuously cast through the billet casting machine to obtain a 150mm×150mm billet.

[0069] S4: During the heating stage, the atmosphere inside the furnace in each section is strictly controlled, and the air-fuel ratio in each section is set to 0.8. When the furnace is charged in cold mode, the total time in the furnace is 80 minutes, the preheating section temperature is 1070℃, the heating section temperature is 1200℃, and the soaking section temperature is 1150℃; when the furnace is charged in hot mode, the total time in the furnace is 70 minutes, the preheating section temperature is 1080℃, the heating section temperature is 1160℃, and the soaking section temperature is 1130℃. During the rolling stage, the initial rolling temperature is 1120℃, the finishing rolling temperature is 1020℃, the wire drawing temperature is 880℃, and the rolling speed is 70m / s.

[0070] The tensile strength of the 30MnSi hot-rolled wire obtained in this embodiment is higher than that of commonly available 30MnSi hot-rolled wire. A comparison of the tensile strength and reduction of area of ​​hot-rolled wire produced with and without argon flow adjustment (the embodiment) is shown in the table below. Table 1: Performance test results of hot-rolled wire produced in the examples and comparative examples

[0071] It should be noted that the process steps and data of the examples and comparative examples with the same serial number are the same, the only difference being whether the argon flow rate is adjusted during the desulfurization process.

[0072] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than that shown in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. In the descriptions corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different blocks may also occur in a different order than disclosed in the description; sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. Each block in a block diagram and / or flowchart, and combinations of blocks in a block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0073] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A low-nitrogen control process for 30MnSi high-speed wire, characterized in that, The process includes: S1: Scrap steel and molten iron are put into an electric furnace. After the steel is tapped, lime, fluorite, silicon-manganese alloy and silicon-iron alloy are added to obtain molten steel. S2: Add molten steel to the LF refining furnace to break the slag shell. During the heating process, argon gas is blown into the bottom of the ladle. The argon flow rate is adjusted during the desulfurization process. The molten steel is heated and fed with pure calcium wire to obtain refined molten steel. The specific steps for adjusting the argon blowing flow rate during the desulfurization process are as follows: S201: Based on the difference between the atmospheric pressure inside and outside the furnace at each collected moment, obtain the pressure difference data at each moment; acquire the temperature image inside the furnace at each moment and divide it evenly, and obtain the temperature sequence at each moment based on the mean temperature data of each sub-region after division; S202: Analyze the element dispersion of the temperature sequence at each moment within the preset period, and combine the distribution similarity of the threshold segmentation results of the temperature sequence to determine the degree of molten steel exposure in each period. S203: Analyze the positive and negative characteristics of the differential pressure data at each moment of each cycle and the quantity characteristics of the high-temperature sub-regions. Combined with the degree of exposed molten steel, determine the argon blowing adjustment index for each cycle. S204: Adjust the argon blowing flow rate based on the argon blowing adjustment index for each cycle; S3: The refined molten steel is continuously cast to obtain a billet; S4: During the heating stage, after setting the temperature of each section and the time in the furnace according to the furnace loading method, the billet is rolled to obtain wire. S5: The wire is air-cooled. After air-cooling, the wire is wound, finished, bundled, weighed and unwound to obtain 30MnSi high-speed wire.

2. The low-nitrogen control process for 30MnSi high-speed wire as described in claim 1, characterized in that, The addition of lime, fluorite, ferrosilicon, and ferrosilicon after tapping the steel is specifically as follows: the tapping temperature is 1625-1640 degrees Celsius, and 30 seconds after tapping, lime containing 12-14 kg / t of steel and fluorite containing 3-4 kg / t of steel are added first, followed by ferrosilicon containing 12-14 kg / t of steel and ferrosilicon containing 6-8 kg / t of steel. The tapping process is carried out with argon blowing throughout, and the argon flow rate is 17-25 NL / min.

3. The low-nitrogen control process for 30MnSi high-speed wire as described in claim 1, characterized in that, The argon flow rate for breaking the slag shell is 50-200 NL / min; the argon flow rate for bottom blowing in the ladle is 400-500 NL / min; and the argon flow rate range for the desulfurization process is 400-500 NL / min.

4. The low-nitrogen control process for 30MnSi high-speed wire as described in claim 1, characterized in that, The specific operation of heating and feeding pure calcium wire into molten steel is as follows: the temperature of molten steel is heated to 1580℃, and the speed of feeding pure calcium wire into molten steel is controlled at 140-150 m / furnace, at which time the argon flow rate is 20-80 NL / min.

5. The low-nitrogen control process for 30MnSi high-speed wire as described in claim 1, characterized in that, The determination of the degree of molten steel exposure in each cycle is specifically as follows: The degree of dispersion of the mean temperature data of all sub-regions at each time point is denoted as the temperature dispersion value. The sub-regions whose average temperature data at each time point is greater than the segmentation threshold are designated as high-temperature sub-regions. Based on the serial numbers of all high-temperature sub-regions at each time point, a regional position sequence is formed. The first mean is obtained by averaging the distance characteristics between the regional positional sequences of all adjacent times in each cycle. The negative correlation mapping result of the first mean of each cycle is positively fused with the mean of the discrete temperature values ​​at all times to obtain the steel exposure index for each cycle.

6. The low-nitrogen control process for 30MnSi high-speed wire as described in claim 5, characterized in that, The determination of the argon blowing adjustment index for each cycle includes: Obtain the number of high-temperature sub-regions at each time point in each cycle; Calculate the similarity between the sequence of differential pressure data at all times in each cycle and the sequence of the quantities obtained at all times, and record it as the first correlation value for each cycle; Let the argon blowing regulation index of the i-th cycle be denoted as Its formula is as follows: In the formula, The number of negative numbers in the differential pressure sequence of the i-th period; The first correlation value for the i-th period; It is an exponential function with the natural constant e as the base; Let be the steel exposure index for the i-th period. This indicates the preset parameters.

7. The low-nitrogen control process for 30MnSi high-speed wire as described in claim 1, characterized in that, The adjustment of the argon blowing flow rate specifically involves: Calculate the product of the normalized value of the argon blowing adjustment index and the preset weighting coefficient, and add the product to the preset argon blowing flow rate for each cycle to obtain the adjusted argon blowing flow rate for each cycle.

8. The low-nitrogen control process for 30MnSi high-speed wire as described in claim 1, characterized in that, The specific operation for continuous casting of refined molten steel is as follows: the molten steel is injected into the tundish of the continuous casting machine, the molten steel level is controlled at 800-900mm, and the slag layer thickness in the tundish is controlled at 70-80mm; during the continuous casting process, the crystallization electromagnetic stirring is turned on throughout, the current intensity is controlled at 300-350A, the frequency is 3-3.5Hz, the cooling water control mode adopts the weak cooling mode, and the casting speed is controlled at 2.9-3.3m / min.

9. The low-nitrogen control process for 30MnSi high-speed wire as described in claim 1, characterized in that, The setting of the temperature and furnace time for each section according to the furnace loading method is as follows: When the furnace is loaded in cold mode, the total time in the furnace is 70-80 minutes, the preheating zone temperature is 1040-1070℃, the heating zone temperature is 1100-1200℃, and the soaking zone temperature is 1090-1150℃. When the furnace is loaded in hot loading mode, the total time in the furnace is 60-70 minutes, the preheating zone temperature is 1050-1080℃, the heating zone temperature is 1120-1160℃, and the soaking zone temperature is 1090-1130℃.

10. The low-nitrogen control process for 30MnSi high-speed wire as described in claim 1, characterized in that, The specific operation for rolling the billet is as follows: the initial rolling temperature is 1090-1130℃, the finishing rolling temperature is 980-1020℃, the wire drawing temperature is 860-880℃, and the rolling speed is 50-70m / s.

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