CN101538636B - Ladle furnace use nitrogen gas nitrogen alloying process - Google Patents
Ladle furnace use nitrogen gas nitrogen alloying process Download PDFInfo
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- CN101538636B CN101538636B CN2008100348230A CN200810034823A CN101538636B CN 101538636 B CN101538636 B CN 101538636B CN 2008100348230 A CN2008100348230 A CN 2008100348230A CN 200810034823 A CN200810034823 A CN 200810034823A CN 101538636 B CN101538636 B CN 101538636B
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 397
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 192
- 238000009847 ladle furnace Methods 0.000 title claims abstract description 60
- 238000000034 method Methods 0.000 title claims abstract description 33
- 238000005275 alloying Methods 0.000 title claims abstract description 32
- 230000008569 process Effects 0.000 title claims abstract description 28
- 229910001873 dinitrogen Inorganic materials 0.000 title claims abstract description 13
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 80
- 239000010959 steel Substances 0.000 claims abstract description 80
- 229910001220 stainless steel Inorganic materials 0.000 claims abstract description 45
- 239000010935 stainless steel Substances 0.000 claims abstract description 43
- 238000007664 blowing Methods 0.000 claims abstract description 39
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims abstract description 32
- 229910052786 argon Inorganic materials 0.000 claims abstract description 16
- 238000007670 refining Methods 0.000 claims abstract description 10
- 238000011010 flushing procedure Methods 0.000 claims description 42
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 claims description 16
- 239000000203 mixture Substances 0.000 claims description 16
- 241001062472 Stokellia anisodon Species 0.000 claims description 10
- 238000003756 stirring Methods 0.000 claims description 8
- 229910045601 alloy Inorganic materials 0.000 abstract description 19
- 239000000956 alloy Substances 0.000 abstract description 19
- 238000004519 manufacturing process Methods 0.000 abstract description 14
- 238000003723 Smelting Methods 0.000 abstract description 9
- 125000000449 nitro group Chemical group [O-][N+](*)=O 0.000 abstract 1
- 239000011651 chromium Substances 0.000 description 10
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 9
- 239000007789 gas Substances 0.000 description 8
- 238000004458 analytical method Methods 0.000 description 7
- 230000006870 function Effects 0.000 description 7
- 239000011572 manganese Substances 0.000 description 7
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- 238000005260 corrosion Methods 0.000 description 5
- 230000007797 corrosion Effects 0.000 description 5
- 238000005121 nitriding Methods 0.000 description 4
- 229910001566 austenite Inorganic materials 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000001276 controlling effect Effects 0.000 description 3
- 229910001039 duplex stainless steel Inorganic materials 0.000 description 3
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 238000009749 continuous casting Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910000734 martensite Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 210000003625 skull Anatomy 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910000885 Dual-phase steel Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 241001417490 Sillaginidae Species 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000005256 carbonitriding Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 229940110728 nitrogen / oxygen Drugs 0.000 description 1
- 125000004433 nitrogen atom Chemical group N* 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000009711 regulatory function Effects 0.000 description 1
- 238000010079 rubber tapping Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
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- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention relates to a ladle furnace use nitrogen gas nitrogen alloying process. The process comprises the following steps: a) smelting nitrogen-contained stainless steel, controlling the components of the molten steel except the nitrogen to the targeted components, and controlling a nitrogen flush initial temperature at 30 to 50 DEG C above a refining treatment out-station temperature; b) during the nitrogen bottom blowing for the smelting of the nitrogen-contained stainless steel in the LF furnace, adding 1 to 20 ppm of nitrogen to each standard cube of nitrogen; c) during the nitrogen bottom blowing for the micro-alloying treatment, controlling the nitrogen flow at 6 to 120m<3>/h and the nitrogen flush pressure at 0.60 to 0.80 MPa; and d) when the nitrogen bottom blowing is finished, carrying out the argon bottom blowing for 4 to 6 minutes with the argon flow of 2 to 20 m<3>/h so as to average the stainless steel components and temperature. The process adds the nitrogen alloying function through the nitrogen bottom flowing to the ladle furnace (LF) in the prior stainless steel production process so as to replace a nitro alloy, make the nitrogen-contained stainless steel carry out continuous and stable nitrogen alloying in the ladle furnace, improve the purity of the molten steel, and consequently improve the molten steel quality and reduce the production cost.
Description
Technical field
The present invention relates to stainless smelting technology, particularly ladle furnace (LF) is smelted the ladle furnace use nitrogen gas nitrogen alloying process that nitrogen-contained stainless steel is produced.
Background technology
Stainless steel is meant the general name of the steel alloy of corrosive naturees such as having opposing atmosphere, acid, alkali and salt.Usually said " stainless steel " is meant its corrosion resistance, is attributable in the environment of oxidation, forms one deck chromic oxide surface film, and this layer film has and do not dissolve, can recover voluntarily and imperforate characteristics.Argon oxygen decarburizing furnace (AOD) is to produce one of stainless main refining means.
88% stainless steel adopts two step method production in the world at present, and wherein 76% is by the production of AOD stove.Ladle furnace (LF stove) is arranged on one of refining unit between AOD stove and the continuous casting, it connects this two production processes swimmingly, improve the productivity of two processes, improving steel quality, enlarge kind, optimize technology, reducing aspects such as consumption and bringing into play huge effect, is that modern stainless steel is made steel indispensable important procedure.
Stainless classification is classified with metallographic structure usually: ferritic stainless steel; Austenitic stainless steel; Martensite Stainless Steel; The austenite-ferrite duplex stainless steel, the austeno-martensite duplex stainless steel; PH Stainless Steel.And austenitic stainless steel can be divided into control nitrogen type, middle nitrogen type, three kinds of nitrogenous austenitic stainless steels of high nitrogen type according to the nitrogen content difference.
The beneficial effect of nitrogen in nitrogenous austenitic stainless steel:
(1) nitrogen is the most effective solution strengthening element.The advantageous effect of nitrogen in austenitic stainless steel mainly is to be produced by the nitrogen element that is solid-solubilized in the steel.
(2) nitrogen is at about 25 times of the suitable Ni of effect that enlarges austenitic area and stable austenite.Some steel grade begins to adopt cheap nitrogen at present, and manganese replaces valuable nickel to produce austenitic stainless steel.
(3) nitrogen can crystal grain thinning.Nitride particles can stop austenitic growing up in heat treatment process, also helps surface cementation, the carbonitriding of steel, can improve the surface property of steel.
(4) nitrogen can obviously improve the anti-general corrosion of stainless steel, spot corrosion, stress corrosion and intergranular corrosion performance.
(5) nitrogen plays an important role to duplex stainless steel as austenite former.
The nitrogen alloying process that the AOD stove is smelted nitrogen-contained stainless steel mainly contains two kinds: 1) nitrogen blowing is carried out alloying; 2) add nitro-alloy and carry out alloying.A kind of technology in back has cost height, the uppity shortcoming of nitrogen content in the application of AOD.And the exploitation and the application of nitrogen alloying technology fully, can be consistent with the metallurgy characteristic of gas flexibly with AOD, have the remarkable advantage that production cost is low, can produce the high nitrogen-containing product, but its difficult point is accurately to control nitrogen content in the AOD stove.
At present, all be in the AOD stove with nitrogen gas nitrogen alloying process both at home and abroad, nitrogen/oxygen mixes the gas alloying that blows in smelting process.Chinese patent CN02135251.8 disclosed " AOD stove nitrogen gas nitrogen alloying process ", it comprises following two steps: the dissolution process of (1) nitrogen in stainless steel, promptly before whole smelting process blowing argon gas, be blown into nitrogen in the AOD stove always and smelt, nitrogen is reached capacity in stainless steel; (2) subtractive process of a part of nitrogen-atoms, promptly use argon gas bubbles refining theory, remove a part of nitrogen content, make that the dissolved nitrogen content reaches within the desired scope of steel grade in the steel, just, go to the argon gas that is blown into different time (or the amount of being blown into) in the AOD stove in tapping according to the steel grade difference.Application nitrogen dissolves in the AOD stove and removes theory, regulates nitrogen, the argon gas amount of being blown into, and produces nitrogen-contained stainless steel and dual phase steel, replaces the technology of former nitro-alloy nitrogen pick-up, has reduced the production cost of nitrogen-contained stainless steel.But AOD reaction in furnace dynamic conditions is very good, blows a certain amount of argon gas or nitrogen in the very short time, will cause the nitrogen in the molten steel sharply to change, and wants accurately to control nitrogen content in still difficulty relatively of ± 50ppm.
LF stove (external refining equipment) has following function:
(1) agitating function, evenly molten steel composition and temperature promote inclusion floating and slag-metal reaction;
(2) molten steel heating and temperature controlling function are accurately controlled liquid steel temperature;
(3) refining function comprises wash heat, deoxidation, the degassing, desulfurization, removes inclusion and inclusion modification processing etc.;
(4) alloying function (comprising line feeding) is carried out narrow Composition Control to molten steel;
(5) production regulatory function, balanced steel-making one continuous casting production.
The LF stove all is to carry out alloying with various corresponding alloys, and following drawback is arranged:
(1) nitro-alloy is not a pure metal, contains impurity, adds more nitro-alloy and can pollute stainless molten steel, influences the molten steel purity, thereby can influence steel quality.
(2) if smelt initially, bigger from the nitrogen content goals value, need to add more nitro-alloy, this can cause the fluctuation of other alloying constituents and exceed standard, and causes the stainless steel off analysis.
(3) the nitro-alloy price comparison is expensive, adds more nitro-alloy, and cost obviously increases.
(4) because the stainless steel skull is very hard, when adding nitro-alloy, the part nitro-alloy usually is added on the skull, can not fuse into molten steel, cause the recovery rate instability of nitrogen, and nitrogen component is inhomogeneous.
Summary of the invention
The objective of the invention is to develop a kind of ladle furnace use nitrogen gas nitrogen alloying process, ladle furnace (LF) in the existing stainless steel production technique is increased bottom blowing nitrogen gas nitrogen alloying function, substitute nitro-alloy, make nitrogen-contained stainless steel can carry out nitrogen alloying sustainedly and stably at the LF stove, improve the molten steel purity, thereby the raising steel quality improves nitrogen-contained stainless steel and is smelt rate, reduces production costs.
The present invention is at ladle furnace (LF stove) station, set up one tunnel nitrogen tube, be parallel to original ladle furnace BOTTOM ARGON BLOWING tracheae, increase corresponding nitrogen tube Controlling System, can switch nitrogen, argon gas, utilize the original porous plug of ladle furnace, bottom blowing nitrogen makes the LF stove can carry out the alloying of nitrogen sustainedly and stably when smelting nitrogen-contained stainless steel, improve the molten steel purity, thereby the raising steel quality improves nitrogen-contained stainless steel and is smelt rate, reduces production costs.
Particularly, technical scheme of the present invention is:
Ladle furnace use nitrogen gas nitrogen alloying process, it comprises the steps:
A) smelt nitrogen-contained stainless steel, control is denitrogenated molten steel composition in addition to target component, ladle furnace treatment capacity 110t～130t in ladle furnace; The nitrogen flushing starting temperature is controlled at above 30 ℃～50 ℃ of refining treatment out-station temperature;
When b) the LF stove is smelted nitrogen-contained stainless steel bottom blowing nitrogen, but every standard cube nitrogen nitrogen pick-up 1～20ppm; Wherein, nitrogen content was when 300～1000ppm before the stainless molten steel nitrogen flushing was handled, and nitrogen nitrogen pick-up coefficient is 100～800 (ppm/m
3) t; Nitrogen content was when 1001～2000ppm before the stainless molten steel nitrogen flushing was handled, and nitrogen nitrogen pick-up coefficient is 200～900 (ppm/m
3) t; Nitrogen content was when 2001～5000ppm before the stainless molten steel nitrogen flushing was handled, and nitrogen nitrogen pick-up coefficient is 300～1200 (ppm/m
3) t; Nitrogen content was when 5001～8000ppm before the stainless molten steel nitrogen flushing was handled, and nitrogen nitrogen pick-up coefficient is 400～2000 (ppm/m
3) t;
C) bottom blowing nitrogen carries out the microalloying processing, and processing air pressure is atmospheric condition, and nitrogen flow is at 6～120m
3/ h, nitrogen flushing pressure: 0.60Mpa～0.80Mpa;
D) after bottom blowing nitrogen finishes, the soft stirring of argon bottom-blowing 4～6 minutes, argon flow amount is at 2～20m
3/ h fully stirs, evenly stainless steel composition and temperature.
For realizing accurately controlling the nitrogen content of smelting process, utilize the nitrogen content software for calculation to calculate the bottom blowing nitrogen amount.Adopt to set the nitrogen flushing amount in the actually operating, time and nitrogen flushing amount, nitrogen flow are relevant.The nitrogen flushing amount is gentle-quality of molten steel interfacial area, steel, molten steel density, apparent positive reaction rate constant, constantly the inner nitrogen concentration of molten steel, constantly mass transfer coefficient in molten steel of the solubleness, nitrogen of the inner nitrogen concentration of molten steel, nitrogen, nitrogen activity quotient, nitrogen flushing flow, initial nitrogen content and with the difference of target nitrogen content relation is arranged.The nitriding percentage amounts increases with air-blowing quantity, and Cr is bigger to its influence simultaneously, and the plain rate of nitriding increases with the increase of Cr content.Temperature is bigger to stainless solubleness influence, and with the rising of temperature, solubleness diminishes.
Smelt nitrogen-contained stainless steel, before the LF stove carries out alloying with nitrogen, the Composition Control beyond denitrogenating is arrived target component, molten steel treatment capacity 110t～130t.Because molten steel has temperature drop during LF furnace bottom nitrogen blowing, temperature drop is made up of two portions, and a part is the ladle heat absorption, and per minute falls 0.3～0.6 ℃; It is endothermic process that nitrogen fuses into molten steel, and bottom blowing nitrogen per minute falls 0.6～1.1 ℃; So the nitrogen flushing starting temperature is controlled at above 30～50 ℃ of refining treatment out-station temperature.
Because the nitriding percentage amounts increases with the nitrogen flushing amount, chromium is bigger to its influence simultaneously, and nitriding speed increases with the increase of chromium content.Temperature is bigger to stainless solubleness influence, and with the rising of temperature, solubleness diminishes.When the LF stove is smelted nitrogen-contained stainless steel bottom blowing nitrogen, but every standard cube nitrogen nitrogen pick-up 1ppm～20ppm, nitrogen content was when 300～1000ppm before wherein the stainless molten steel nitrogen flushing was handled, and nitrogen nitrogen pick-up coefficient is 100～800 (ppm/m
3) t; Nitrogen content was when 1001～2000ppm before the stainless molten steel nitrogen flushing was handled, and nitrogen nitrogen pick-up coefficient is 200～900 (ppm/m
3) t; Nitrogen content was when 2001～5000ppm before the stainless molten steel nitrogen flushing was handled, and nitrogen nitrogen pick-up coefficient is 300～1200 (ppm/m
3) t; Nitrogen content was when 5001～8000ppm before the stainless molten steel nitrogen flushing was handled, and nitrogen nitrogen pick-up coefficient is 400～2000 (ppm/m
3) t.
Stainless steel target nitrogen content after the composition of the stainless molten steel before therefore handling according to nitrogen flushing, temperature, the processing calculates the nitrogen injection amount.
Bottom blowing nitrogen carries out microalloying to be handled.The bottom blowing nitrogen flow is controlled at not serious exposed being advisable of molten steel; Processing air pressure is atmospheric condition, and nitrogen flow is at 6～120m
3/ h, nitrogen flushing pressure: 0.60Mpa～0.80Mpa.
After bottom blowing nitrogen finishes, the soft stirring of argon bottom-blowing 4～6 minutes, argon flow amount is at 2～20m
3/ h fully stirs, evenly stainless steel composition and temperature.
Thereby nitrogen is to reduce CO dividing potential drop decarburization and cr yield in the main effect of AOD, stirs molten steel, improves metallurgical power and learns condition, and AOD smelts the later stage and blows with nitrogen, can not satisfy the accurate control of nitrogen-contained stainless steel nitrogen in smelting process technically.And the LF stove is blown into nitrogen in the bottom by porous plug, carry out nitrogen alloying, it is high to remedy AOD nitrogen content control accuracy, can substitute and reduce the nitro-alloy consumption of (being used to adjust nitrogen content), improve the molten steel purity, thereby the raising steel quality improves nitrogen-contained stainless steel and is smelt rate, reduces cost.External nitrogen-contained stainless steel is smelted the basic AOD of employing nitrogen content stove inner control, and refining station (LF, VOD) is finely tuned the nitrogen content operation with nitro-alloy.
Beneficial effect of the present invention
Compared with prior art, the present invention has following advantage:
(1) at the LF stove, adopt bottom blowing nitrogen to carry out alloying, according to the nitrogen component and the target component of the austenitic stainless steel before handling, go out to jet flow and time computer control winding-up flow and time by control nitrogen computed in software.Simple, convenient, thus make nitrogen-contained stainless steel can carry out the alloying of nitrogen sustainedly and stably at LF.
(2) the LF stove can make the nitrogen content control accuracy improve 20～30ppm than original LF with the nitro-alloy control accuracy with nitrogen gas nitrogen alloying process, accurately controls nitrogen content at target value ± 50ppm.
(3) nitrogen nitrogen pick-up is compared with nitro-alloy nitrogen pick-up, and every nitrogen pick-up 200ppm can reduce cost 100～150 yuan/ton, remarkable in economical benefits.
(4) adopt bottom blowing nitrogen to carry out alloying and compare with adding nitro-alloy, the weight of bottom blowing nitrogen can be ignored, and can not cause the fluctuation of other molten steel compositions and exceeds standard, and nitrogen-contained stainless steel is smelt rate and can be guaranteed.
(5) adopt bottom blowing nitrogen to carry out alloying and compare with adding nitro-alloy, because nitrogen gas purity 99.9% does not contain impurity, can not pollute stainless molten steel, do not influence the molten steel purity, steel quality obviously improves.
(6) bottom blowing nitrogen, nitrogen can fuse into molten steel fully, and the nitrogen recovery rate is stable.
(7) because bottom blowing nitrogen can stir molten steel, nitrogen component is more even.
(8) nitrogen is cheap, and cost can be ignored.
Embodiment
The present invention will be further described below in conjunction with embodiment:
Embodiment 1
1, LF molten steel initial condition
(1) initial nitrogen content: 0.036%～0.040%
(2) initiated process temperature: 1575 ℃～1585 ℃
(3) molten steel amount: 110t～130t
2, LF handles actual achievement
(1) handles air pressure: atmospheric condition
(2) nitrogen flushing pressure: 0.69Mpa～0.71Mpa
(3) nitrogen flushing time: 59.5min～60.7min
(4) nitrogen flushing flow: 39m
3/ h～41m
3/ h
(5) bottom blowing nitrogen amount: 39.8Nm
3～40.2Nm
3
3, steel grade one is in the nitrogen microalloying actual achievement of LF
Composition analysis
| Element | C? | Si? | Mn? | S? | P? | Cr? | Ni? | N? |
| Handle initial | 0.031? | 0.36? | 0.95? | 0.004? | 0.018? | 18.08? | 8.05? | 0.038? |
| Handle terminal point | 0.0307? | 0.35? | 0.95? | 0.002? | 0.018? | 18.10? | 8.06? | 0.068? |
Embodiment 2
1, LF molten steel initial condition
(1) initial nitrogen content: 0.143%～0.144%
(2) initiated process temperature: 1535 ℃～1545 ℃
(3) molten steel amount: 110t～130t
2, LF handles actual achievement
(1) handles air pressure: atmospheric condition
(2) nitrogen flushing pressure: 0.68Mpa～0.70Mpa
(3) nitrogen flushing time: 5.7min～6.4min
(4) nitrogen flushing flow: 119m
3/ h～121m
3/ h
(5) bottom blowing nitrogen amount: 9.8Nm
3～10.2Nm
3
3, steel grade two is in the nitrogen microalloying actual achievement of LF
Composition analysis
| Element | C? | Si? | Mn? | S? | P? | Cr? | Ni? | Mo? | Cu? | N? |
| Handle initial | 0.0170? | 0.510? | 1.34? | 0.001? | 0.027? | 17.40? | 6.60? | 0.15? | 0.14? | 0.1435? |
| Handle terminal point | 0.0168? | 0.508? | 1.35? | 0.001? | 0.027? | 17.42? | 6.61? | 0.15? | 0.14? | 0.1450? |
Embodiment 3
1, LF molten steel initial condition
(1) initial nitrogen content: 0.118%～0.122%
(2) initiated process temperature: 1585 ℃～1595 ℃
(3) molten steel amount: 110t～130t
2, LF handles actual achievement
(1) handles air pressure: atmospheric condition
(2) nitrogen flushing pressure: 0.69Mpa～0.71Mpa
(3) nitrogen flushing time: 49.8min～50.2min
(4) nitrogen flushing flow: 35m
3/ h～38m
3/ h
(5) bottom blowing nitrogen amount: 29.8Nm
3～30.2Nm
3
3, steel grade three is in the nitrogen microalloying actual achievement of LF
Composition analysis
| Element | C? | Si? | Mn? | S? | P? | Cr? | Ni? | Mo? | N? |
| Handle initial | 0.022? | 0.57? | 1.4? | 0.005? | 0.020? | 21.52? | 5.07? | 2.86? | 0.120? |
| Handle terminal point | 0.021? | 0.58? | 1.4? | 0.004? | 0.021? | 21.53? | 5.07? | 2.86? | 0.150? |
Embodiment 4
1, LF molten steel initial condition
(1) initial nitrogen content: 0.236%～0.240%
(2) initiated process temperature: 1535 ℃～1545 ℃
(3) molten steel amount: 110t～130t
2, LF handles actual achievement
(1) handles air pressure: atmospheric condition
(2) nitrogen flushing pressure: 0.70Mpa～0.71Mpa
(3) nitrogen flushing time: 19.8min～20.2min
(4) nitrogen flushing flow: 28m
3/ h～31m
3/ h
(5) bottom blowing nitrogen amount: 9.8Nm
3～10.2Nm
3
3, steel grade four is in the nitrogen microalloying actual achievement of LF
Composition analysis
| Element | C? | Si? | Mn? | S? | P? | Cr? | Ni? | Mo? | N? |
| Handle initial | 0.022? | 0.51? | 6? | 0.004? | 0.023? | 21.08? | 12.99? | 2? | 0.238? |
| Handle terminal point | 0.020? | 0.50? | 6? | 0.004? | 0.024? | 21.07? | 13.0? | 2? | 0.250? |
Embodiment 5
1, LF molten steel initial condition
(1) initial nitrogen content: 0.430%～0.440%
(2) initiated process temperature: 1545 ℃～1555 ℃
(3) molten steel amount: 110t～130t
2, LF handles actual achievement
(1) handles air pressure: atmospheric condition
(2) nitrogen flushing pressure: 0.72Mpa～0.74Mpa
(3) nitrogen flushing time: 21.4min～21.8min
(4) nitrogen flushing flow: 27m
3/ h～29m
3/ h
(5) bottom blowing nitrogen amount: 9.8Nm
3～10.2Nm
3
3, steel grade five is in the nitrogen microalloying actual achievement of LF
Composition analysis
| Element | C? | Si? | Mn? | S? | P? | Cr? | Ni? | Mo? | N? |
| Handle initial | 0.02? | 0.41? | 6? | 0.002? | 0.027? | 24? | 16? | 7.1? | 0.435? |
| Handle terminal point | 0.02? | 0.41? | 6? | 0.002? | 0.027? | 24? | 16? | 7.1? | 0.450? |
Embodiment 6
1, LF molten steel initial condition
(1) initial nitrogen content: 0.690%～0.700%
(2) initiated process temperature: 1625 ℃～1635 ℃
(3) molten steel amount: 110t～130t
2, LF handles actual achievement
(1) handles air pressure: atmospheric condition
(2) nitrogen flushing pressure: 0.79Mpa～0.81Mpa
(3) nitrogen flushing time: 89.6min～90.3min
(4) nitrogen flushing flow: 19.8m
3/ h～20.3m
3/ h
(5) bottom blowing nitrogen amount: 29.8Nm
3～30.2Nm
3
3, steel grade six is in the nitrogen microalloying actual achievement of LF
Composition analysis
| Element | C? | Si? | Mn? | S? | P? | Cr? | Ni? | N? |
| Handle initial | 0.125? | 0.43? | 14.96? | 0.003? | 0.027? | 22.56? | 0.3? | 0.696? |
| Handle terminal point | 0.125? | 0.42? | 14.96? | 0.003? | 0.026? | 22.57? | 0.3? | 0.750? |
From the foregoing description as can be seen, the austenite stainless smelting steel of different content adopts method of the present invention can reach the nitrogen pick-up effect.
In sum, the present invention increases bottom blowing nitrogen gas nitrogen alloying function to ladle furnace (LF) in the existing stainless steel production technique, substitute nitro-alloy, make nitrogen-contained stainless steel can carry out nitrogen alloying sustainedly and stably at the LF stove, improve the molten steel purity, thereby the raising steel quality improves nitrogen-contained stainless steel and is smelt rate, reduces production costs.
Claims (1)
1. ladle furnace use nitrogen gas nitrogen alloying process, it comprises the steps:
A) smelt nitrogen-contained stainless steel, control is denitrogenated molten steel composition in addition to target component, ladle furnace treatment capacity 110t～130t in ladle furnace; The nitrogen flushing starting temperature is controlled at above 30 ℃～50 ℃ of refining treatment out-station temperature;
When b) the LF stove is smelted nitrogen-contained stainless steel bottom blowing nitrogen, but every standard cube nitrogen nitrogen pick-up 1～20ppm; Wherein, nitrogen content was when 300～1000ppm before the stainless molten steel nitrogen flushing was handled, and nitrogen nitrogen pick-up coefficient is 130～800 (ppm/m
3) t; Nitrogen content was when 1001～2000ppm before the stainless molten steel nitrogen flushing was handled, and nitrogen nitrogen pick-up coefficient is 200～900 (ppm/m
3) t; Nitrogen content was when 2001～5000ppm before the stainless molten steel nitrogen flushing was handled, and nitrogen nitrogen pick-up coefficient is 300～1200 (ppm/m
3) t; Nitrogen content was when 5001～8000ppm before the stainless molten steel nitrogen flushing was handled, and nitrogen nitrogen pick-up coefficient is 400～2000 (ppm/m
3) t;
C) bottom blowing nitrogen carries out the microalloying processing, and processing air pressure is atmospheric condition, and nitrogen flow is at 6～120m
3/ h, nitrogen flushing pressure: 0.60MPa～0.80MPa;
D) after bottom blowing nitrogen finishes, the soft stirring of argon bottom-blowing 4～6 minutes, argon flow amount is at 2～20m
3/ h fully stirs, evenly stainless steel composition and temperature.
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| CN102312175B (en) * | 2011-07-01 | 2013-03-13 | 山西太钢不锈钢股份有限公司 | Method for manufacturing stainless steel plate used for thermonuclear fusion reactor |
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