CN115820985A - Method for accurately controlling nitrogen content of molten steel of deformed steel bar - Google Patents
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 439
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 265
- 239000010959 steel Substances 0.000 title claims abstract description 265
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 220
- 238000000034 method Methods 0.000 title claims abstract description 77
- 238000007664 blowing Methods 0.000 claims abstract description 80
- 238000003723 Smelting Methods 0.000 claims abstract description 43
- 238000007670 refining Methods 0.000 claims abstract description 42
- 238000004458 analytical method Methods 0.000 claims abstract description 28
- 239000007789 gas Substances 0.000 claims abstract description 10
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 62
- 229910052786 argon Inorganic materials 0.000 claims description 31
- 238000013461 design Methods 0.000 claims description 9
- PWKWDCOTNGQLID-UHFFFAOYSA-N [N].[Ar] Chemical compound [N].[Ar] PWKWDCOTNGQLID-UHFFFAOYSA-N 0.000 claims description 7
- 238000003756 stirring Methods 0.000 claims 2
- 230000008569 process Effects 0.000 abstract description 36
- 238000004519 manufacturing process Methods 0.000 abstract description 8
- 229910045601 alloy Inorganic materials 0.000 abstract description 7
- 239000000956 alloy Substances 0.000 abstract description 7
- 239000000463 material Substances 0.000 abstract description 3
- 238000005272 metallurgy Methods 0.000 abstract description 2
- 230000000087 stabilizing effect Effects 0.000 abstract description 2
- 238000009847 ladle furnace Methods 0.000 description 27
- 230000001276 controlling effect Effects 0.000 description 15
- 238000005070 sampling Methods 0.000 description 11
- 238000005275 alloying Methods 0.000 description 9
- 239000002436 steel type Substances 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 6
- 230000006872 improvement Effects 0.000 description 6
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 5
- 238000009749 continuous casting Methods 0.000 description 4
- 229910000976 Electrical steel Inorganic materials 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 229910052720 vanadium Inorganic materials 0.000 description 3
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910001199 N alloy Inorganic materials 0.000 description 2
- SKKMWRVAJNPLFY-UHFFFAOYSA-N azanylidynevanadium Chemical compound [V]#N SKKMWRVAJNPLFY-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000006356 dehydrogenation reaction Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- PNXOJQQRXBVKEX-UHFFFAOYSA-N iron vanadium Chemical compound [V].[Fe] PNXOJQQRXBVKEX-UHFFFAOYSA-N 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 229910000922 High-strength low-alloy steel Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 241001062472 Stokellia anisodon Species 0.000 description 1
- 229910001315 Tool steel Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- 239000000378 calcium silicate Substances 0.000 description 1
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
- OSMSIOKMMFKNIL-UHFFFAOYSA-N calcium;silicon Chemical compound [Ca]=[Si] OSMSIOKMMFKNIL-UHFFFAOYSA-N 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 238000005121 nitriding Methods 0.000 description 1
- 230000024121 nodulation Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000033764 rhythmic process Effects 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- 238000009489 vacuum treatment Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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Abstract
The invention relates to the technical field of metallurgy, in particular to a method for accurately controlling nitrogen content of molten steel of deformed steel bar. The method comprises the following steps: 1) Taking a molten steel sample for component analysis after the molten steel reaches an LF refining furnace; 2) Determining a ladle bottom blowing mode and time according to the nitrogen content of incoming molten steel and the nitrogen requirement of steel grades; 3) And (4) taking a molten steel sample at the smelting end point for component analysis. According to the nitrogen content of the molten steel entering the LF refining furnace, the ladle bottom blowing process with different gas media, flow and time is implemented, the accurate control of the nitrogen content of the molten steel is realized, the rolled material performance of the deformed steel bar can be effectively improved, and the method has great significance for improving the product quality and reducing the production cost. The method comprises the steps of refining molten steel in LF, taking a molten steel sample for component analysis, determining a ladle bottom blowing mode and bottom blowing time according to the nitrogen content requirement of steel grades and the nitrogen content of incoming molten steel, taking the molten steel sample at a smelting end point for component analysis, realizing accurate control of the nitrogen content of the molten steel, and stabilizing the steel performance under the condition of reducing alloy cost.
Description
Technical Field
The invention relates to the technical field of metallurgy, in particular to a method for accurately controlling nitrogen content of molten steel of deformed steel bar.
Background
Blowing nitrogen into molten steel is a new nitrogen-containing steel production technology with low cost, and the application in steel smelting process is wide. Steel works have methods for producing nitrogen-containing steel grades by blowing nitrogen at the bottom of a converter, blowing nitrogen at the bottom of a steel ladle, blowing nitrogen at RH and the like. RH is a widely used molten steel vacuum refining apparatus (mainly a steam jet pump system), has the functions of decarburization, degassing, temperature rise, inclusion removal and the like, and is used for producing high-quality clean steel. However, when RH nitrogen blowing alloying is carried out, the control precision of nitrogen components is between 20ppm and 40ppm, and the problem of large fluctuation of nitrogen components exists, thereby influencing the production cost and the steel grade quality of enterprises.
In particular, the nitrogen content of deformed steel bars has great influence on the properties of the steel materials, the yield strength is low when the nitrogen content is low, the plasticity of the steel is reduced when the nitrogen content is high, most manufacturers stabilize the nitrogen absorption amount of molten steel when the molten steel is contacted with nitrogen or air in a smelting process by regulating the nitrogen content of raw materials, measures such as regulating the type and flow of gas blown from the bottom of a steel ladle in a refining process and reducing the fluctuation of the nitrogen content of the molten steel are adopted, the measures cannot be adopted according to the actual nitrogen content of the steel in the smelting process, the fluctuation of the nitrogen content in the steel is large, the fluctuation of the performance of the steel is serious, and the steel performance is not suitable for producing waste products in serious cases. In addition, in order to ensure that the nitrogen content in steel reaches the standard, a large amount of high-price nitriding alloy is added in the steel-making process, so that the alloy cost is high.
The existing RH nitrogen-blowing alloying nitrogen component content control process comprises the following steps:
the application patent CN102296160A discloses a low-cost RH molten steel nitrogen increasing and controlling process, which adopts a process route of converter-ladle furnace refining-RH furnace vacuum treatment-continuous casting to smelt and utilizes a RH molten steel nitrogen increasing and controlling process method of a vanadium-nitrogen alloy precipitation strengthened high-strength low-alloy steel grade. The method has the characteristics that: 1. vanadium-iron is adopted to carry out vanadium alloying to replace vanadium-nitrogen alloy; 2. the nitrogen flow in the RH nitrogen increasing and controlling process is controlled according to 800-1200NL/min, and the vacuumizing treatment time is 8-10min, so that the nitrogen content in the steel is 80-120 ppm. 3. The RH vacuum finishes the calcium treatment by adopting a calcium silicate wire. The method adopts vanadium iron and calcium silicon wires, the vanadium alloying and calcium treatment costs are high, RH adopts a steam jet pump vacuum system, the vacuum degree control range in the RH vacuum nitrogen increasing and controlling process is not mentioned, and the vacuum degree control range is an important process parameter for RH molten steel nitrogen increasing. Although the RH vacuum-pumping treatment time is 8-10min, the nitrogen fluctuation range of the nitrogen steel is within 40ppm, and the nitrogen fluctuation is wide.
Patent application CN105154628A discloses an RH dehydrogenation and nitrogen increase process for nitrogen-containing steel, wherein nitrogen is adopted as a lifting gas in the whole RH process, and the purposes of dehydrogenation and nitrogen increase are achieved by controlling the process parameters such as the flow and pressure of the nitrogen, the vacuum degree of RH, the vacuum treatment time and the like in the RH refining process. The method RH adopts a steam jet pump vacuum system, and mainly aims to dehydrogenate, ensure the nitrogen content of nitrogen-containing steel to be 80-120ppm, ensure the nitrogen fluctuation range to be within 40ppm and have wide fluctuation.
Patent CN104962698B discloses a method for accurately controlling the nitrogen content of oriented electrical steel, and introduces a method for accurately controlling the nitrogen content of oriented electrical steel produced by RH, and the control precision of the nitrogen content of steel is high (+/-5 ppm). However, the RH method adopts a steam jet pump vacuum system, and the steel grade is limited to oriented electrical steel; meanwhile, the production process comprises the following steps: molten iron pretreatment → 210 ton converter smelting → RH refining → continuous casting, wherein argon and nitrogen are switched twice in the RH refining process, the nitrogen pressure in the RH vacuum nitrogen increasing stage is 1.1-1.6 MPa, the circulation flow is 200-280 Nm3/h, the vacuum degree of the RH furnace is 3-5 KPa, and the defect of the circulation gas flow can cause the serious defect of 'nodulation' in the vacuum tank.
In conclusion, the nitrogen content in the steel has great influence on the mechanical properties of the steel, and the plasticity of the steel is reduced and the ductility of the steel is reduced along with the increase of the nitrogen content in the steel; nitrogen also aggravates aging of steel, reduces cold workability of steel, causes embrittlement of weld heat affected zones, cracks a casting blank, and causes intergranular corrosion. Therefore, the reduction of the nitrogen content of molten steel is always the aim of pursuing the smelting of high-quality steel, particularly, the alloying quantity is large in the smelting process of wear-resistant and grinding tool steel, the alloying difficulty of an LF (ladle furnace) is large, the smelting period is long, in order to improve the alloying efficiency, shorten the smelting period and ensure the production rhythm of continuous casting, the LF is usually stirred by using large argon to promote alloying, and the strong dynamic condition of the large argon is in contradiction with the nitrogen content control, so that the nitrogen content of the steel for smelting the series of steel is higher, the internal and surface quality of continuous casting billets is poorer, the steel plate and the subsequent processing performance are influenced, and finally the steel benefit cannot be brought into play.
Therefore, in view of the defects of the existing RH refining nitrogen blowing alloying nitrogen content control technology, a method for accurately controlling the nitrogen content of molten steel of deformed steel bars is urgently needed to be provided, the quality of steel is improved, and the production cost is reduced.
Disclosure of Invention
The invention aims to provide a method for accurately controlling the nitrogen content of molten steel of deformed steel bar, which comprises the steps of taking a molten steel sample for component analysis after the molten steel enters an LF refining furnace, determining a ladle bottom blowing mode and time according to the nitrogen content of incoming molten steel and the nitrogen requirement of steel type, taking the molten steel sample at a smelting end point for component analysis, realizing accurate control of the nitrogen content of the molten steel of the deformed steel bar, and stabilizing the performance of steel products under the condition of reducing alloy cost.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the invention provides a method for accurately controlling the nitrogen content of molten steel of deformed steel bar, which comprises the following steps:
1) Taking a molten steel sample for component analysis after the molten steel reaches an LF refining furnace;
2) Determining a ladle bottom blowing mode and time according to the nitrogen content of incoming molten steel and the nitrogen content requirement of steel grades;
3) And (4) taking a molten steel sample at the smelting end point for component analysis.
As a modification of the method, in the step 2), the nitrogen content requirement of the steel grade is determined according to the design requirement upper limit of the steel grade, and the requirement value of the nitrogen content of the steel grade = (the design nitrogen content upper limit of the steel grade is-30 ppm) ± 5ppm.
As a modification of the method, in the step 2), the nitrogen content of the incoming molten steel is determined by spectrometer analysis.
As a modification of the above method, in the step 2), determination of the ladle bottom blowing mode and time: the ladle bottom blowing mode is determined according to the nitrogen content of incoming molten steel, and comprises three modes of bottom blowing nitrogen, bottom blowing nitrogen and argon switching and bottom blowing argon.
As an improvement of the method, when the nitrogen content of the incoming molten steel = the required value of the nitrogen content of the steel grade, the bottom blowing adopts a bottom blowing nitrogen-argon switching mode, the switching point of nitrogen and argon is +/-30 s when the molten steel is smelted to 1/2, namely the molten steel is fed into the station and is subjected to bottom blowing by adopting nitrogen, and when the molten steel is smelted to 1/2 +/-30 s, the molten steel is subjected to bottom blowing by adopting argon; the nitrogen content of the incoming molten steel is higher than the required nitrogen content of the steel grade, and the switching time of bottom blowing nitrogen argon is shifted forward by 110-130s when the nitrogen content is 10ppm higher than the required nitrogen content of the steel grade.
As an improvement of the method, when the nitrogen content of the incoming molten steel is higher than the nitrogen content required by steel grade and is more than 50ppm or the forward time is reached to the bottom blowing time, the nitrogen content of the molten steel is reduced by a bottom blowing argon high-flow mode.
As an improvement of the method, the large flow of the bottom-blown argon is 5.5 to 6.5L/t.min.
As an improvement of the method, the nitrogen content of the incoming molten steel is lower than the required nitrogen content of the steel grade, and the switching time of bottom blowing nitrogen argon is shifted to 110-130s after every 10ppm lower than the required nitrogen content of the steel grade.
As an improvement of the method, when the nitrogen content of the incoming molten steel is lower than the required nitrogen content of steel grade and is more than 50ppm or the backward movement time reaches the bottom blowing end time, the nitrogen content of the molten steel is increased by a bottom blowing nitrogen high-flow mode.
As an improvement of the method, the large flow rate of the bottom blowing nitrogen is 5.5-6.5L/t.min.
According to the invention, the nitrogen content of the molten steel in the smelting process is increased along with the increase of the contact time with nitrogen and the increase of the ambient nitrogen concentration, and is reduced along with the increase of the contact time with argon (or other gases) and the increase of the ambient argon (or other gases) concentration, the change condition of the nitrogen content of the molten steel under different nitrogen blowing (argon blowing) parameters in the smelting process of the refining furnace is determined through theoretical research and field practice data, a molten steel accurate nitrogen control model is determined, and the accurate control of the nitrogen content of the molten steel according to requirements is realized.
According to the nitrogen content of the molten steel entering the LF refining furnace, the ladle bottom blowing process with different gas media, flow and time is implemented, the accurate control of the nitrogen content of the molten steel is realized, the rolled material performance of the deformed steel bar can be effectively improved, and the method has great significance for improving the product quality and reducing the production cost.
Compared with the prior art, the invention has the advantages that:
1) According to the invention, the molten steel sample is taken for component analysis after the molten steel is refined to LF, the ladle bottom blowing mode and the bottom blowing time are determined according to the nitrogen content requirement of the steel type and the nitrogen content of the incoming molten steel, and the component analysis is carried out by sampling at the smelting end point, so that the accurate control of the nitrogen content of the molten steel is realized, and the steel performance is stabilized under the condition of reducing the alloy cost.
2) The invention can improve the performance of the rolled steel of the steel grade and broaden the space for reducing the design cost of the components of the steel grade.
Detailed Description
The present invention will be further described with reference to the following specific examples.
In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, shall fall within the protection scope of the present application.
The invention provides a method for controlling nitrogen content of molten steel of deformed steel bar, which comprises the following steps:
1) Taking a molten steel sample for component analysis after the molten steel reaches an LF refining furnace;
2) Determining a ladle bottom blowing mode and time according to the nitrogen content of incoming molten steel and the nitrogen requirement of steel grades; the nitrogen content requirement of the steel grade is determined according to the upper limit of the design requirement of the steel grade, the required value of the nitrogen content of the steel grade = (the upper limit of the design nitrogen content of the steel grade is-30 ppm) ± 5ppm, and the nitrogen content of the incoming molten steel is determined by the analysis of a spectrometer; determination of ladle bottom blowing mode and time: when the nitrogen content of incoming molten steel is a required value of the nitrogen content of steel grades, a nitrogen-argon switching mode is adopted in a ladle bottom blowing mode, namely, the molten steel is blown at the bottom by adopting nitrogen when entering the station, and argon is used for bottom blowing when the molten steel is smelted to 1/2 within +/-30 s; the nitrogen content of the incoming station molten steel is higher than the required nitrogen content of the steel grade, the switching time of bottom blowing nitrogen and argon is advanced for 110-130s when the nitrogen content of the incoming station molten steel is higher than the required nitrogen content of the steel grade by 10ppm, or the nitrogen content of the incoming station molten steel is higher than the required nitrogen content of the steel grade by more than 50ppm or the advancing time is advanced to the bottom blowing open time, the nitrogen content of the molten steel is reduced by bottom blowing argon with the mode of prolonging the bottom blowing time (the large flow of the bottom blowing argon is 5.5-6.5L/t.min); and when the nitrogen content of the incoming molten steel is lower than the nitrogen content required by the steel grade and is 10ppm every time the nitrogen content of the incoming molten steel is lower than the nitrogen content required by the steel grade, the switching time of bottom blowing nitrogen and argon is shifted backwards for 110-130s, and when the nitrogen content of the incoming molten steel is lower than the nitrogen content required by the steel grade and is more than 50ppm or the shifting time is shifted backwards to the bottom blowing finish time, the nitrogen content of the molten steel is increased in a bottom blowing nitrogen large flow mode (the bottom blowing nitrogen large flow is 5.5-6.5L/t.min). The nitrogen content of the molten steel in the smelting process is increased along with the increase of the contact time with nitrogen and the increase of the ambient nitrogen concentration, and is decreased along with the increase of the contact time with argon (or other gases) and the increase of the ambient argon (or other gases) concentration, the change condition of the nitrogen content of the molten steel under different nitrogen blowing (argon blowing) parameters in the smelting process of the refining furnace is determined through theoretical research and field practice data, a molten steel accurate nitrogen control model is determined, and the accurate control of the nitrogen content of the molten steel according to requirements is realized.
3) And (4) taking a molten steel sample at the smelting end point for component analysis.
The invention relates to a 150t refining furnace accurate nitrogen control model (HRB 400E-1 steel grade nitrogen upper limit requirement 130ppm, steel grade nitrogen requirement value 100ppm, refining bottom blowing time 20 minutes smelting process, HRB400E-1 steel grade nitrogen upper limit and refining bottom blowing time of each steel plant are different, each enterprise sets enterprise standards in national standards according to respective production process of the enterprise), and each parameter in the model is determined according to the steel grade nitrogen content requirement and the refining time. The bottom blowing flow is determined according to the quantity of molten steel and smelting requirements and generally divided into normal flow and large flow, wherein the normal flow is generally 0.6-1L/min per ton of steel, the large flow value is 5.5-6.5L/t.min, the flow value thickening numerical value in the following table is nitrogen (after the numerical value + N), other flow numerical values are argon, and the unit is L/min.
Refining smelting process accurate nitrogen control model (150 ton refining furnace steel HRB 400E-1)
The present invention is further illustrated by the following examples and comparative examples, but the scope of the present invention is not limited thereto.
Example 1 accurate control of nitrogen content in molten steel of 150 ton LF refining furnace
The invention discloses a method for accurately controlling the nitrogen content of molten steel of deformed steel bar, which comprises the following steps:
1) After the molten steel reaches an LF refining furnace, a molten steel sample is taken for component analysis, the nitrogen content of the molten steel is 80ppm, the requirement upper limit of the nitrogen content of smelting steel seeds is 130ppm, and the optimal control value of the nitrogen content of the molten steel is 100ppm;
2) The technological requirement of bottom blowing time in the smelting process of the steel type LF refining furnace is 20min, nitrogen (with the flow of 105L/min) is adopted for bottom blowing 14min before smelting in the furnace, and argon (with the flow of 105L/min) is adopted for bottom blowing 6min later;
3) And (3) taking a molten steel sample at the smelting end point for component analysis, wherein the nitrogen content of the molten steel is 100ppm.
Example 2 accurate control of nitrogen content in molten steel of 150 ton LF refining furnace
The invention discloses a method for accurately controlling the nitrogen content of molten steel of deformed steel bar, which comprises the following steps:
1) Sampling the molten steel after the molten steel reaches an LF refining furnace, and carrying out component analysis, wherein the nitrogen content of the molten steel is 120ppm, the upper limit of the requirement on the nitrogen content of smelting steel seeds is 130ppm, and the optimal control value of the nitrogen content of the molten steel is 100ppm;
2) The process requirement of bottom blowing time in the smelting process of the steel type LF refining furnace is 20min, nitrogen (with the flow rate of 105L/min) is adopted for bottom blowing 6min before smelting in the furnace, and argon (with the flow rate of 105L/min) is adopted for bottom blowing 14min later;
3) Sampling at the smelting end point for component analysis, wherein the nitrogen content of the molten steel is 99ppm.
Comparative example 1 accurate control of nitrogen content in molten steel of LF refining furnace of 150 tons
1) Sampling the molten steel after the molten steel reaches an LF refining furnace, and carrying out component analysis, wherein the nitrogen content of the molten steel is 80ppm;
2) The process requirement of bottom blowing time in the smelting process of the steel type LF refining furnace is 20min, and nitrogen (with the flow of 105L/min) is adopted in the smelting bottom blowing of the furnace;
3) Sampling at the smelting end point for component analysis, wherein the nitrogen content of the molten steel is 130ppm.
Comparative example 2 accurate control of nitrogen content in molten steel of 150-ton LF refining furnace
1) Sampling the molten steel after the molten steel reaches an LF refining furnace, and carrying out component analysis, wherein the nitrogen content of the molten steel is 120ppm;
2) The process requirement of bottom blowing time in the smelting process of the steel type LF refining furnace is 20min, and nitrogen (with the flow rate of 105L/min) is adopted in the smelting bottom blowing of the furnace;
3) Sampling at the smelting end point for component analysis, wherein the nitrogen content of the molten steel is 152ppm.
Comparative example 3 accurate control of nitrogen content in molten steel of 150-ton LF refining furnace
1) Sampling the molten steel after the molten steel reaches an LF refining furnace, and carrying out component analysis, wherein the nitrogen content of the molten steel is 80ppm;
2) The process requirement of bottom blowing time in the smelting process of the steel type LF refining furnace is 20min, and argon (with the flow of 105L/min) is adopted in the smelting bottom blowing of the furnace;
3) Sampling at the smelting end point for component analysis, wherein the nitrogen content of the molten steel is 60ppm.
Comparative example 4 accurate control of nitrogen content in molten steel of LF refining furnace
1) Sampling the molten steel after the molten steel reaches an LF refining furnace, and carrying out component analysis, wherein the nitrogen content of the molten steel is 120ppm;
2) The process requirement of bottom blowing time in the smelting process of the steel type LF refining furnace is 20min, and argon (with the flow rate of 105L/min) is adopted in the smelting bottom blowing of the furnace;
3) Sampling at the smelting end point for component analysis, wherein the nitrogen content of the molten steel is 85ppm.
The nitrogen contents of the examples and comparative examples were compared, and the results are shown in Table 1.
TABLE 1 comparison of nitrogen contents in molten steels
According to the invention, through comparison of the implementation case and the comparison case, the nitrogen content of the molten steel at the refining end point of the implementation case reaches the nitrogen content range required by the steel grade, the product performance can be effectively improved, a space is provided for optimizing components of the steel grade (alloy elements such as manganese and vanadium of the steel grade are adjusted, the alloy cost is reduced), the nitrogen content of the molten steel at the refining end point of the comparison case deviates from the nitrogen content required value of the steel grade, the influence on the product quality stability is caused, and the refined nitrogen content of the individual comparison case exceeds the upper limit required by the steel grade design and is an unqualified product. The invention can improve the performance of the rolled steel of the steel grade and broaden the space for reducing the design cost of the components of the steel grade.
Those skilled in the art will recognize that the invention may be practiced without these specific details.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. A method for accurately controlling the nitrogen content of molten steel of deformed steel bars comprises the following steps:
1) Taking a molten steel sample for component analysis after the molten steel reaches an LF refining furnace;
2) According to the nitrogen content of incoming molten steel and the nitrogen content requirement of steel grades, determining the bottom blowing mode and time of the ladle;
3) And (4) taking a molten steel sample at the smelting end point for component analysis.
2. The method for accurately controlling the nitrogen content of molten steel of deformed steel bar according to claim 1, wherein in the step 2), the nitrogen content requirement of the steel grade is determined according to the design requirement upper limit of the steel grade, and the required value of the nitrogen content of the steel grade = (the design nitrogen content upper limit of the steel grade-30 ppm) ± 5ppm.
3. The method for accurately controlling the nitrogen content of molten steel of deformed steel bar according to claim 2, wherein in the step 2), the determination of the ladle bottom blowing mode and time is as follows: the ladle bottom blowing mode is determined according to the nitrogen content of incoming molten steel, and comprises three modes of bottom blowing nitrogen, bottom blowing nitrogen and argon switching and bottom blowing argon.
4. The method for accurately controlling the nitrogen content of molten steel of deformed steel bar according to claim 3, wherein when the nitrogen content of incoming molten steel is equal to the required value of the nitrogen content of steel, a bottom blowing nitrogen-argon switching mode is adopted for bottom blowing, the switching point of nitrogen and argon is +/-30 s when the molten steel is smelted to 1/2, the nitrogen is adopted for bottom blowing when the molten steel is incoming, and the argon is adopted for bottom blowing when the molten steel is smelted to 1/2 +/-30 s.
5. A method for accurately controlling the nitrogen content of molten steel of deformed steel bar according to claim 3 or 4, wherein when the nitrogen content of incoming molten steel is higher than the required nitrogen content of steel grade, the switching time of bottom-blown nitrogen argon is advanced by 110-130s every time the nitrogen content of incoming molten steel is 10ppm higher than the required nitrogen content of steel grade.
6. The method for accurately controlling the nitrogen content of molten steel in deformed steel bar according to claim 5, wherein when the nitrogen content of the incoming molten steel is higher than the required nitrogen content value of steel grade by 50ppm or when the current moving time reaches the bottom blowing open time, the nitrogen content of the molten steel is reduced by a bottom blowing argon gas high-flow stirring mode.
7. The method for accurately controlling the nitrogen content of molten steel of deformed steel bar according to claim 6, wherein the large flow rate of bottom-blown argon is 5.5-6.5L/t.min.
8. The method for accurately controlling the nitrogen content of molten steel of deformed steel bar as claimed in claim 3 or 4, wherein when the nitrogen content of incoming molten steel is lower than the required nitrogen content of steel grade, the switching time of bottom-blown nitrogen argon is shifted back by 110-130s every time when the nitrogen content of incoming molten steel is 10ppm lower than the required nitrogen content of steel grade.
9. The method for accurately controlling the nitrogen content of molten steel of deformed steel bar according to claim 8, wherein when the nitrogen content of the incoming molten steel is lower than the required nitrogen content value of steel grade by 50ppm or when the backward moving time reaches the bottom blowing end time, the nitrogen content of the molten steel is increased by a bottom blowing nitrogen high-flow stirring mode.
10. The method for accurately controlling the nitrogen content of molten steel of deformed steel bar according to claim 9, wherein the large flow rate of bottom-blown nitrogen is 5.5-6.5L/t.min.
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Citations (3)
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| CN101613783A (en) * | 2009-08-07 | 2009-12-30 | 山西太钢不锈钢股份有限公司 | A kind of method of nitrogen pick-up in refining furnace |
| CN111041153A (en) * | 2019-12-12 | 2020-04-21 | 首钢京唐钢铁联合有限责任公司 | Method and system for smelting high-nitrogen tin plate molten steel |
| CN114875210A (en) * | 2022-03-30 | 2022-08-09 | 山东莱钢永锋钢铁有限公司 | Automatic nitrogen-argon switching process for refining furnace |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101613783A (en) * | 2009-08-07 | 2009-12-30 | 山西太钢不锈钢股份有限公司 | A kind of method of nitrogen pick-up in refining furnace |
| CN111041153A (en) * | 2019-12-12 | 2020-04-21 | 首钢京唐钢铁联合有限责任公司 | Method and system for smelting high-nitrogen tin plate molten steel |
| CN114875210A (en) * | 2022-03-30 | 2022-08-09 | 山东莱钢永锋钢铁有限公司 | Automatic nitrogen-argon switching process for refining furnace |
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