CN117051195A - Method for controlling ER70S-6 nitrogen content by optimizing converter deoxidation process - Google Patents
Method for controlling ER70S-6 nitrogen content by optimizing converter deoxidation process Download PDFInfo
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- CN117051195A CN117051195A CN202310874879.1A CN202310874879A CN117051195A CN 117051195 A CN117051195 A CN 117051195A CN 202310874879 A CN202310874879 A CN 202310874879A CN 117051195 A CN117051195 A CN 117051195A
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- nitrogen content
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 149
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 75
- 238000000034 method Methods 0.000 title claims abstract description 45
- 230000008569 process Effects 0.000 title claims abstract description 26
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 67
- 239000010959 steel Substances 0.000 claims abstract description 67
- 238000010079 rubber tapping Methods 0.000 claims abstract description 25
- 239000002893 slag Substances 0.000 claims abstract description 20
- 230000002829 reductive effect Effects 0.000 claims abstract description 13
- 238000005275 alloying Methods 0.000 claims abstract description 8
- 230000004048 modification Effects 0.000 claims abstract description 6
- 238000012986 modification Methods 0.000 claims abstract description 6
- 238000007664 blowing Methods 0.000 claims description 18
- 238000004519 manufacturing process Methods 0.000 claims description 13
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 10
- 229910052782 aluminium Inorganic materials 0.000 claims description 10
- 238000009826 distribution Methods 0.000 claims description 10
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 9
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 9
- 239000004571 lime Substances 0.000 claims description 9
- 238000003466 welding Methods 0.000 claims description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 6
- 238000003723 Smelting Methods 0.000 claims description 4
- 238000011065 in-situ storage Methods 0.000 claims description 4
- 230000002401 inhibitory effect Effects 0.000 claims description 4
- 229910052786 argon Inorganic materials 0.000 claims description 3
- 238000007670 refining Methods 0.000 claims description 3
- 238000006392 deoxygenation reaction Methods 0.000 claims 3
- 238000004886 process control Methods 0.000 claims 3
- 238000006243 chemical reaction Methods 0.000 abstract description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 11
- 239000001301 oxygen Substances 0.000 abstract description 11
- 229910052760 oxygen Inorganic materials 0.000 abstract description 11
- 239000007788 liquid Substances 0.000 abstract description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- 238000005266 casting Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000010521 absorption reaction Methods 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 238000009628 steelmaking Methods 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 238000009749 continuous casting Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 238000005070 sampling Methods 0.000 description 3
- 239000012496 blank sample Substances 0.000 description 2
- 238000007667 floating Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 230000036961 partial effect Effects 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000009851 ferrous metallurgy Methods 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 238000010517 secondary reaction Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/30—Regulating or controlling the blowing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/36—Processes yielding slags of special composition
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention discloses a method for controlling ER70S-6 nitrogen content by optimizing a converter deoxidization process, which utilizes the characteristic of high free oxygen content in molten steel, cancels the converter deoxidization process, namely, does not carry out deoxidization alloying operation in the converter tapping process, furthest reserves the oxygen content in the molten steel, reduces the gas-liquid reaction interfacial area by active oxygen in the molten steel, and controls the molten steel to contact with air in the deoxidization process so as to increase nitrogen; meanwhile, only a certain modification operation is carried out on molten steel top slag in the steel ladle in the tapping process, so that the top slag covers the surface of molten steel in the steel ladle, and the exposure of molten steel is reduced and the contact of the molten steel with air is reduced, so that nitrogen is absorbed.
Description
Technical Field
The invention relates to the technical field of ferrous metallurgy, in particular to a method for controlling the nitrogen content of ER70S-6 by optimizing a converter deoxidation process.
Background
Nitrogen is used as a solid solution strengthening element, so that the strength of the steel can be improved; as a gap atom, the plasticity, toughness, welding performance and thermal stress area toughness of the steel are obviously reduced, so that the brittleness of the steel is increased, the continuous casting blank is cracked, and meanwhile, drawing brittle failure is very easy to occur, and the production smooth and the welding quality are seriously affected. ER70S-6, however, is used as a high quality CO 2 The gas shielded welding wire should have good plastic drawing properties and good welding properties. Therefore, the control of nitrogen content during the production of ER70S-6 is particularly important. Nitrogen has a larger ionic radius than hydrogen. The diffusion coefficient in steel is two orders of magnitude smaller than hydrogen, and it is difficult to use a vacuum process with very good dehydrogenation effect for denitrification. In addition, nitrogen is not as active as oxygen, and can form inclusion with strong deoxidizing agents such as aluminum, barium, silicon and the like, and is removed by floating; nitrogen is much less active and nitrides with most alloying elements decompose at high temperatures and cannot be removed by floating. It follows that nitrogen content control in steel is a difficult task.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a method for controlling the nitrogen content of ER70S-6 by optimizing a converter deoxidization process, which solves the problem of reducing the nitrogen content of molten steel in ER70S-6 steel smelting by adopting converter deoxidization not only to modify top slag operation in ER70S-6 steel steelmaking production.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention discloses a method for controlling the nitrogen content of ER70S-6 by optimizing a converter deoxidation process, which comprises the following steps: R70S-6 controls the smelting point blowing times and point blowing time of the converter in production, improves the hit rate of the converting end point of the converter, ensures that the point blowing times are less than or equal to 1 time, ensures that the point blowing time is less than or equal to 40S, controls the carbon content of the molten steel at the end point to be less than or equal to 0.04%, and ensures that the end point temperature T is more than or equal to 1640 ℃; inhibiting the operation of blowing the furnace mouth by carbon pulling and nitrogen; the bottom blowing medium of the converter is required to be blown with argon in the whole course; the tapping operation time of the converter is reduced, and welding wire steel production is not arranged within 10 times of the service life of a tap hole; after the tapping operation is started, no ladle internal deoxidization alloying operation is adopted, only top slag lime is added in the tapping process, the addition amount of 1.8-2.2kg/t steel is added, and the top slag lime is started to be added when the tapping amount reaches 1/2 of the total amount of the ladle; after tapping, adding proper amount of aluminum particles with the aluminum content of 99% according to the slag tapping condition to perform pre-deoxidization modification operation on the slag tapping, wherein the addition amount of the aluminum particles is less than or equal to 0.2kg/t steel;
after the operation is finished, the steel ladle is lifted and transported to the working procedure treatment after the refining is started.
2, only top slag lime is added in the tapping process, and the addition amount of the top slag lime is 2kg/t steel.
Further, the LF in-situ nitrogen content distribution is 0.0020-0.0028% and the average nitrogen content is 0.0024%.
Further, the LF off-site nitrogen content distribution is 0.0024-0.0035%, and the average nitrogen content is 0.0031%.
Further, the nitrogen content distribution of the casting blank is 0.0037-0.0042%, and the average nitrogen content is 0.0040%.
Compared with the prior art, the invention has the beneficial technical effects that:
the invention utilizes the characteristic of high free oxygen content in molten steel, cancels the converter deoxidization process, namely, does not carry out deoxidization alloying operation in the converter tapping process, furthest maintains the oxygen content in the molten steel, reduces the gas-liquid reaction interface area of active oxygen in the molten steel, and controls the contact of the molten steel with air in the deoxidization process so as to increase nitrogen. Meanwhile, only a certain modification operation is carried out on molten steel top slag in the steel ladle in the tapping process, so that the top slag covers the surface of molten steel in the steel ladle, and the exposure of molten steel is reduced and the contact of the molten steel with air is reduced, so that nitrogen is absorbed.
Detailed Description
The equilibrium solubility of nitrogen in steel at atmospheric and normal steelmaking temperatures is calculated as follows: 1/2N 2 The relation between the free energy of N and temperature is:
ΔG 1 ＝860+5.71T(1)
ΔG 2 ＝2900+2.85T(2)
ΔG 3 ＝86400-15.6T(3)
ΔG 4 ＝1150+12.6T(4)
the four results are different. But they all showed ΔG at steelmaking temperatures 0 Above 0, the reaction cannot proceed; and all but formula (3) show a temperature increase ΔG 0 The reaction proceeds more difficult with an increase. This is not the case. Whereas from the thermal effect of the reaction the dissolution of nitrogen is an endothermic reaction, an increase in temperature is favourable for the reaction, consisting of lgK = - Δh 0 /4.57T+ΔS 0 As shown in/4.57T, the temperature increases and the K value increases, which is in accordance with practice. The direction and limits of the reaction cannot be estimated from the free energy equation.
Furthermore, the method is known from the law and activity of the Sitting and the like:
lgK (L) ＝-188/T-0.246
the solubility of nitrogen in the molten iron and the temperature are obtained, and the relation between the nitrogen partial pressure and the alloy element is as follows:
(5) Formula (6) is the solubility of nitrogen in steel. The solubility of nitrogen in iron was calculated to be 6.04% according to the formula (5) at 1600℃and 0.08MPa (O.79 atm) nitrogen partial pressure. Thus, the steel making molten steel in the atmosphere is strongly nitrogen-absorbing, and the nitrogen content in the molten steel is not balanced so far, and more nitrogen is absorbed if the condition is met.
When the surface active element (oxygen or sulfur) contained in the molten steel is higher than a certain degree, the nitrogen absorption reaction on the surface of the molten steel becomes a limiting link of nitrogen absorption, the nitrogen absorption becomes a secondary reaction, and the speed equation is as follows:
in the formula, [ N ] represents the nitrogen content in the steel at the moment t;
t-reaction time, s;
k-mass transfer coefficient, m/s;
f-air-liquid interfacial area, square meter;
v-liquid volume, m 3 ；
[N] Flat plate -nitrogen content of molten steel in equilibrium with gas phase
From the analysis, the oxygen content in the molten steel is increased, oxygen and FeO are enriched on the surface of the molten steel, so that the coverage rate of iron on the surface of the molten steel is reduced, which is equivalent to reducing the gas-liquid reaction interface area, reducing the reaction interface F in the formula, and reducing the nitrogen absorption speed of the molten steel. Therefore, the oxygen content in the molten steel is increased, and nitrogen absorption of the molten steel can be reduced.
Aiming at the problems in the technical background, the embodiment provides a method for optimizing the converter deoxidizing process to control the content of ER70S-6 nitrogen by combining thermodynamic theoretical mechanism calculation of nitrogen increase and a reaction formula for inhibiting molten steel nitrogen increase in the technical scheme.
In order that the above aspects, features and advantages of the invention will be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof.
The invention is implemented on the basis of pouring production process equipment of a 120t converter-LF external refining-150 multiplied by 150mm billet continuous casting machine. ER70S-6 controls the smelting point blowing times and point blowing time of a converter in production, improves the hit rate of the converting end point of the converter, ensures that the point blowing times are less than or equal to 1 time, ensures that the point blowing time is less than or equal to 40S, controls the carbon content of the molten steel at the end point to be less than or equal to 0.04%, and ensures that the end point temperature T is more than or equal to 1640 ℃; inhibiting the operation of blowing the furnace mouth by carbon pulling and nitrogen; the bottom blowing medium of the converter is required to be blown with argon in the whole course; the tapping operation time of the converter is reduced, and welding wire steel production is not arranged within 10 times of the service life of a tap hole; after the tapping operation is started, no ladle internal deoxidization alloying operation is adopted, only top slag lime is added in the tapping process, the addition amount of steel is 2kg/t, and the top slag lime is started to be added when the tapping amount reaches 1/2 of the total amount of the ladle. After tapping, adding proper amount of aluminum particles with the aluminum content of 99% according to the condition of slag, and performing pre-deoxidation modification operation on the slag, wherein the addition amount of the aluminum particles is less than or equal to 0.2kg/t steel.
After the operation is finished, the steel ladle is lifted and transported to the working procedure treatment after the refining is started.
After the technology of the invention is used, the nitrogen content of ER70S-6 steel grade is stably controlled by canceling the converter deoxidization alloying process, and the application effect is obvious.
Application case
The production process is as follows: 120t converter-LF external refining-150×150mm billet continuous casting machine. The test group and the blank control group selected ER70S-6 steel grades each underwent a 3-furnace production test. The test scheme is that blank groups are produced according to the original production process, LF in-place, off-place and casting blanks are sampled at the same time, and 3 samples are sampled per heat; the experimental group is produced according to the patent method, the same sampling scheme is adopted, the nitrogen content change in molten steel of the two process methods is compared, and the experimental data are summarized in the following table:
table 1 nitrogen content of blank samples
According to sampling analysis, in steel samples produced by a blank group normal deoxidizing process, the LF in-situ nitrogen content distribution is 0.0034-0.0044%, and the average nitrogen content is 0.0040%; LF off-site nitrogen content distribution is 0.0045-0.0059%, average nitrogen content is 0.0051%; the nitrogen content distribution of casting blank is 0.0052-0.0072%, and the average nitrogen content is 0.0061%.
Table 2 nitrogen content of test samples of experimental group
According to sampling analysis, in steel grades produced by the converter deoxidization alloying process of the experimental group, the LF in-situ nitrogen content distribution is 0.0020-0.0028%, and the average nitrogen content is 0.0024%; LF off-site nitrogen content distribution is 0.0024-0.0035%, and average nitrogen content is 0.0031%; the nitrogen content distribution of casting blank is 0.0037-0.0042% and the average nitrogen content is 0.0040%.
As is obvious from comparison of two groups of test data, after the patent is used, LF is in place and is out of place, the nitrogen content in casting blank sample steel is obviously reduced, and finally the nitrogen content of the casting blank is reduced from average 0.0061% to average 0.0040% and is reduced by 0.0021%. The patent method has obvious effect on controlling the nitrogen content in ER70S-6 steel.
The above embodiments are only illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope defined by the claims of the present invention without departing from the design spirit of the present invention.
Claims (5)
1. A method for optimizing converter deoxidization process control ER70S-6 nitrogen content, comprising: R70S-6 controls the smelting point blowing times and point blowing time of the converter in production, improves the hit rate of the converting end point of the converter, ensures that the point blowing times are less than or equal to 1 time, ensures that the point blowing time is less than or equal to 40S, controls the carbon content of the molten steel at the end point to be less than or equal to 0.04%, and ensures that the end point temperature T is more than or equal to 1640 ℃; inhibiting the operation of blowing the furnace mouth by carbon pulling and nitrogen; the bottom blowing medium of the converter is required to be blown with argon in the whole course; the tapping operation time of the converter is reduced, and welding wire steel production is not arranged within 10 times of the service life of a tap hole; after the tapping operation is started, no ladle internal deoxidization alloying operation is adopted, only top slag lime is added in the tapping process, the addition amount of 1.8-2.2kg/t steel is added, and the top slag lime is started to be added when the tapping amount reaches 1/2 of the total amount of the ladle; after tapping, adding proper amount of aluminum particles with the aluminum content of 99% according to the slag tapping condition to perform pre-deoxidization modification operation on the slag tapping, wherein the addition amount of the aluminum particles is less than or equal to 0.2kg/t steel;
after the operation is finished, the steel ladle is lifted and transported to the working procedure treatment after the refining is started.
2. The method for optimizing a converter deoxidation process to control ER70S-6 nitrogen content of claim 1, wherein only top slag lime is added during tapping and the addition amount is 2kg/t steel.
3. The method of optimizing converter deoxygenation process control ER70S-6 nitrogen content of claim 1 wherein the LF in situ nitrogen content profile is 0.0020-0.0028% and the average nitrogen content is 0.0024%.
4. The method for optimizing converter deoxygenation process control of ER70S-6 nitrogen content of claim 1 wherein LF off-site nitrogen content distribution is 0.0024-0.0035% and average nitrogen content is 0.0031%.
5. The method for optimizing a converter deoxygenation process to control ER70S-6 nitrogen content of claim 1 wherein the billet nitrogen content profile is 0.0037-0.0042% and the average nitrogen content is 0.0040%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310874879.1A CN117051195A (en) | 2023-07-17 | 2023-07-17 | Method for controlling ER70S-6 nitrogen content by optimizing converter deoxidation process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310874879.1A CN117051195A (en) | 2023-07-17 | 2023-07-17 | Method for controlling ER70S-6 nitrogen content by optimizing converter deoxidation process |
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| Publication Number | Publication Date |
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| CN117051195A true CN117051195A (en) | 2023-11-14 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202310874879.1A Pending CN117051195A (en) | 2023-07-17 | 2023-07-17 | Method for controlling ER70S-6 nitrogen content by optimizing converter deoxidation process |
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| Country | Link |
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| CN (1) | CN117051195A (en) |
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2023
- 2023-07-17 CN CN202310874879.1A patent/CN117051195A/en active Pending
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