CN103710486A - Method for improving nitrogen content of steel - Google Patents
Method for improving nitrogen content of steel Download PDFInfo
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- CN103710486A CN103710486A CN201310720215.6A CN201310720215A CN103710486A CN 103710486 A CN103710486 A CN 103710486A CN 201310720215 A CN201310720215 A CN 201310720215A CN 103710486 A CN103710486 A CN 103710486A
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Abstract
The invention provides a method for improving the nitrogen content of steel. The method comprises the following steps of pouring liquid steel at a temperature ranging from 1550 to 1650 DEG C into a container with an air blowing device, wherein the liquid steel contains 0.001-0.04% of O and 0.002-0.08% of S; hoisting the container on the side surface of a magnetic field generator which is composed of a box, an iron core, a coil and a lifting ring, and based on the magnetic induction intensity of the liquid steel in the middle of the steel holding container, applying different magnetic induction intensities correspondingly according to different flow Reynolds numbers of the liquid steel; next, blowing nitrogen or ammonia gas to the container until the nitrogen content is satisfied, and then shutting down the electromagnetic braking magnetic field generator, and tapping steel and casting. The method provided by the invention has the advantages that the flowing speed of the liquid steel is suppressed through electromagnetic braking without pollution, the floating speed of bubbles in the liquid steel can be effectively reduced, the stay time of the bubbles in the liquid steel is prolonged and the conversion efficiency of N2 to [N] is promoted, and therefore, the temperature drop of the liquid steel and the total nitrogen/ammonia gas blowing amount are reduced, the energy source and the resources are greatly saved and the smelting cost is reduced.
Description
Technical field
The invention belongs to smelting technology technical field, relate in particular to a kind of electromagnetism flow control and smelt the method that improves steel nitrogen content.
Background technology
The performance of austenitic stainless steel of nickelalloy is superior, but cost is expensive, so investigator begins one's study and with nitrogen, replaces nickel and carry out stable austenite.Nitrogen is unique gas alloying element, is also the most cheap alloying element, with nitrogen, for nickel, is a new technology of primary study exploitation during current nitrogenous steel is produced.
Nitrogen is strong austenite stabilizer element, can impel stainless steel to form austenite structure.In Ni equivalent calculation, N equivalent is 30 times of Ni.Thereby can replace noble metal Ni with cheap N, Mn, even all replace Ni, to obtain austenitic stainless steel.N compares with C, is more effective solution strengthening element, and increases the effect of refined crystalline strengthening, improves the intensity of steel and does not significantly damage again the toughness of steel.Research shows, 0.10%N can make the room temperature strength (σ of Cr-Ni austenitic stainless steel
b, σ
0.2) raising 60～100MPa.Nitrogen can reduce the trend that forms ferrite and deformation induced martensitic transformation occurs, and under given strength condition, can reduce Precipitation, can also improve the resistance to local corrosion of stainless steel, as spot corrosion, crevice corrosion, intergranular corrosion etc.In addition, nitrogen is also helpful to the creep-resistant property of austenitic stainless steel and antifatigue polishing machine.
In actual production, from the viewpoint of production efficiency and rhythm, can not rely on merely raising smelting pressure and time to improve the nitrogen content of certain steel grade, there is scholar to be optimized dynamic conditionss such as the bottom blowing flow of high-pressure bottom nitrogen flushing method, bottom blowing times, improve refining efficiency, reduce high nitrogen steel and produce the requirement to equipment.
The patent of invention of notification number CN1116241A has been introduced and has been adopted bottom blowing nitrogen bessemerizing whole process, adds the nitrogen pick-up of nitrogen alloy in tapping process, and RH treating processes is usingd the method for nitrogen as the smelting high-nitrogen steel of shielding gas.The patent of invention of publication number CN1563462A has been introduced the method for smelting high-nitrogen steel in vacuum melting environment, by regulating the intake of ammonia to control the rate of decomposition of ammonia, makes molten steel reach required nitrogen content.Publication number is the patent of invention of the CN101235461A ammonia of jetting in smelting process, to improve nitrogen in steel content.Notification number is that the utility model patent of CN201495269U utilizes electroslag remelting furnace smelting high-nitrogen steel.But also by controlling MOLTEN STEEL FLOW state, do not extend bubble residence time in molten steel at present, and then improve the method for the smelting high-nitrogen steel of nitrogen in steel content.
Summary of the invention
Object of the present invention aims to provide a kind of can shortening the heat, and promotes N
2→ [N] efficiency of conversion, reduces molten steel temperature drop and nitrogen flushing/ammonia total amount, the method for the raising steel nitrogen content of save energy and resource.
Research shows, nitrogen blowing or ammonia decomposes no matter, and the process of melting nitrogenous steel all will comprise bubble floating, N
2be decomposed into the solute exchange process that [N] enters molten steel.The size of the length of nitrogen flushing time, unit time nitrogen flushing amount can directly affect nitrogen in steel content.The increase of the prolongation of nitrogen flushing time and unit time nitrogen flushing amount no doubt can improve nitrogen in steel content, but this can increase temperature drop and the nitrogen flushing total amount of molten steel, causes the waste of the energy and resource, also may affect normally carrying out of production simultaneously.
The speed of nitrogen bubble floating and the flow state of molten steel are closely bound up.Under different MOLTEN STEEL FLOW conditions, bubble floating speed is also different.Generally be divided into 4 kinds of situations: during Re<2, can adopt Stokes'formula to calculate ascent rate; During 2<Re<400, produce circulation in bubble population, reduced the resistance of motion, bubble floating speed is than Stokes'formula calculated value large 500%; During 400<Re<5000, bubble shape ovalize, during floating, bubble swings, and motion twist, relatively disperses; During Re>5000, bubble is ball cap shape, during floating, liquid is had to strong stirring action, bubble floating now, and speed and liquid property are irrelevant, with equivalent diameter d
gsquare root be directly proportional.
Based on above-mentioned consideration, the solution that the present invention takes is:
A method that improves steel nitrogen content, is characterized in that, utilizes electromagnetic braking reduction because the molten steel flow speed that bubble floating causes changes, and then extends the residence time of bubble in molten steel, promotes N
2the efficiency of conversion of → [N].Its concrete grammar is:
1, prepare magnetic field generator: magnetic field generator is comprised of casing, iron core, coil and suspension ring; " U " shape iron core is installed in rectangular box, and two external parts of " U " shape iron core lean out outside casing, are wound with coil on iron core, and coil is connected with power supply by cable, and casing is fixed with suspension ring outward.
2, smelting temperature is reached the molten steel of 1550～1650 ℃ pour into there is top blast, in the container of bottom blowing or top end combined air blowing device, steel water oxygen, sulphur content span of control are: O:0.001～0.04%, S:0.002～0.08%.
3, the container that fills molten steel is hung onto to desired location, more at least a set of magnetic field generator is placed on to container side.
4, open magnetic field generator, magnetic field generator output rating is adjusted to required intensity, the magnetic induction density with molten steel place in the middle of melted steel container is as the criterion, and when MOLTEN STEEL FLOW reynolds number Re <2, applying magnetic induction density is the braking magnetic field of 0.002～0.01T; When MOLTEN STEEL FLOW Reynolds number 2<Re<400, applying magnetic induction density is the braking magnetic field of 0.01～0.08T.
5, in container, be blown into nitrogen or ammonia, in molten steel, nitrogen content stops nitrogen flushing after reaching requirement, closes electromagnetic braking magnetic field generator, tapping casting.
The corresponding design of MOLTEN STEEL FLOW speed that the specification of described magnetic field generator, power cause according to the size of ladle, nitrogen flushing or ammonia, container is larger, MOLTEN STEEL FLOW speed is faster, and the size of magnetic field generator is larger, and power is also higher.
Described container is ladle, ladle, steel teeming ladle or plumbago crucible.
100 tons of magnetic field generator physical dimension corresponding to ladle are 2 * 1.5 * 2m.
Beneficial effect of the present invention is:
The present invention, by the pollution-free inhibition MOLTEN STEEL FLOW of electromagnetic braking speed, can effectively slow down molten steel bubble floating speed, extends bubble residence time in molten steel, promotes N
2→ [N] efficiency of conversion, thus molten steel temperature drop and nitrogen flushing/ammonia total amount reduced, and greatly save energy and resource, reduce smelting cost.
Accompanying drawing explanation
Fig. 1 is magnetic field generator structural representation;
Fig. 2 is electromagnetic braking magnetic field generator putting position figure.
In figure: iron core 1, casing 2, coil 3, suspension ring 4, ladle 5, magnetic field generator 6.
Embodiment
First, prepare magnetic field generator 6.Magnetic field generator 6 is comprised of iron core 1, casing 2, coil 3, suspension ring 4." U " shape iron core 1 is installed in rectangular box 2, two external parts of " U " shape iron core 1 lean out in the outside of casing 2, are wound with coil 3 on the recessed part of iron core 1, and coil 3 is connected with power supply by cable, the outside surface of casing 2 is fixed with suspension ring 4, so that handling.The corresponding design of MOLTEN STEEL FLOW speed that the concrete dimensions of magnetic field generator 6 and power need cause according to the size of ladle 5, nitrogen flushing or ammonia, and ladle 5 is larger, MOLTEN STEEL FLOW speed is faster, and the size of magnetic field generator 6 is larger, and power is also higher.
Below in conjunction with embodiment, the present invention will be further described.
Embodiment 1:
Utilize 500kg induction furnace fusing molten steel, adopt magnalium matter crucible splendid attire molten steel.1600 ℃ of smelting temperatures, respectively have electromagnetic braking and without electromagnetic braking situation under carry out bottom blowing nitrogen, air-blowing quantity is 0.1m
3/ (tmin), and nitrogen content in sampling and measuring molten steel.
The long 950mm of casing 2 of electromagnetic braking magnetic field generator 6, wide 550mm, high 700mm.Casing 2 material selection thickness 2mm stainless steels.Adopt a set of electromagnetic braking magnetic field generator 6, magnetic field generator 6 can produce the magnetic field of the strongest about 0.04T.More than the magneticstrength producing at molten steel middle part reaches 0.005T.In molten steel, nitrogen content changes as shown in table 1 with the nitrogen flushing time.
Nitrogen content changing conditions table in molten steel when table 1. has or not electromagnetic braking
As can be seen from Table 1, under identical experiment condition, result when nitrogen content increase will be much larger than brakeless in molten steel while having electromagnetic braking.
Embodiment 2:
For the undersized containers such as plumbago crucible that hold molten metal, the plumbago crucible of need braking can be placed near 6 one yokes of electromagnetic braking magnetic field generator, the magnetic induction density at this place is stronger.The long 950mm of casing 2 of electromagnetic braking magnetic field generator 6, wide 550mm, high 700mm.Casing 2 material selection thickness are 2mm stainless steel.Magnetic field generator 6 can produce the magnetic field of the strongest about 0.04T.
The plumbago crucible external diameter of splendid attire molten steel is 22cm, and smelting temperature reaches 1620 ℃, and electromagnetic braking is carried out in the position that plumbago crucible is placed on to an about 2cm of yoke of distance.With rod iron, stir molten steel, molten steel stops stirring after reaching certain rotating speed, applies electromagnetic braking magnetic field.Molten steel is carried out to electromagnetic braking experiment, and the molten steel Speed Reduction that can be 94.2cm/s by flow velocity about 3 seconds is to static.Now braking magnetic field generator 6 coil received currents is 160A, and the magnetic induction density producing in molten steel central position is at 600～800Gs.
Embodiment 3:
Utilize 100 tons of ladles 5 to adopt bottom blowing nitrogen method nitrogen-containing steel smelting, smelting temperature reaches 1650 ℃.Apply the size of magnetic field generator 6 of electromagnetic braking at 2 * 1.5 * 2m, take two cover magnetic field generators 6 to be placed in pairs ladle 5 both sides, can increase the penetration depth of electromagnetic field, be conducive to the electromagnetic braking of molten steel in the middle of ladle 5.The magneticstrength producing in molten steel reaches 0.005～0.02T left and right.Utilize this device within the identical nitrogen flushing time, result when nitrogen content increase will be much larger than brakeless in molten steel while having electromagnetic braking.
Claims (4)
1. a method that improves steel nitrogen content, is characterized in that, utilizes electromagnetic braking reduction because the molten steel flow speed that bubble floating causes changes, and then extends the residence time of bubble in molten steel, promotes N
2the efficiency of conversion of → [N]; Its concrete grammar is:
(1), prepare magnetic field generator: magnetic field generator is comprised of casing, iron core, coil and suspension ring; " U " shape iron core is installed in rectangular box, and two external parts of " U " shape iron core lean out outside casing, are wound with coil on iron core, and coil is connected with power supply by cable, and casing is fixed with suspension ring outward;
(2), by smelting temperature reach the molten steel of 1550～1650 ℃ pour into there is top blast, in the container of bottom blowing or top end combined air blowing device, steel water oxygen, sulphur content span of control are: O:0.001～0.04%, S:0.002～0.08%;
(3), the container that fills molten steel is hung onto to desired location, more at least a set of magnetic field generator is placed on to container side;
(4), open magnetic field generator, magnetic field generator output rating is adjusted to required intensity, the magnetic induction density with molten steel place in the middle of melted steel container is as the criterion, and when MOLTEN STEEL FLOW reynolds number Re <2, applying magnetic induction density is the braking magnetic field of 0.002～0.01T; When MOLTEN STEEL FLOW Reynolds number 2<Re<400, applying magnetic induction density is the braking magnetic field of 0.01～0.08T;
(5), to ladle, be blown into nitrogen or ammonia, in molten steel, nitrogen content stops nitrogen flushing after reaching requirement, closes electromagnetic braking magnetic field generator, tapping casting.
2. the method for raising steel nitrogen content according to claim 1, it is characterized in that, the corresponding design of MOLTEN STEEL FLOW speed that the specification of described magnetic field generator, power cause according to the size of ladle, nitrogen flushing or ammonia, container is larger, MOLTEN STEEL FLOW speed is faster, the size of magnetic field generator is larger, and power is also higher.
3. the method for raising steel nitrogen content according to claim 1, is characterized in that, described container is ladle, ladle, steel teeming ladle or plumbago crucible.
4. according to the method for the raising steel nitrogen content described in claim 1 or 3, it is characterized in that, 100 tons of magnetic field generator physical dimension corresponding to ladle are 2 * 1.5 * 2 m.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105710348A (en) * | 2014-12-01 | 2016-06-29 | 鞍钢股份有限公司 | Device and method for removing inclusions through refined bubbles |
| 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 |
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| CN1116241A (en) * | 1994-08-03 | 1996-02-07 | 宝山钢铁(集团)公司 | Producing technology of low hydrogen high nitrogen steel |
| KR20030030873A (en) * | 2001-10-11 | 2003-04-18 | 베들레헴 스틸 코포레이션 | A method for operating a steelmaking furnace during a steelmaking process |
| CN1563462A (en) * | 2004-03-18 | 2005-01-12 | 上海交通大学 | Method for smelting high nitrogen steel |
| CN101235461A (en) * | 2007-09-03 | 2008-08-06 | 北京科技大学 | Method for smelting high-nitrogen steel under normal pressure |
| CN201495269U (en) * | 2009-07-17 | 2010-06-02 | 廖大中 | Electroslag remelting furnace electrode and electroslag remelting furnace for smelting high nitrogen steels |
| CN101736121A (en) * | 2009-12-14 | 2010-06-16 | 衡阳华菱连轧管有限公司 | Method for smelting 07Cr2MoW2VNbB steel in electric furnace and using same to form round pipe billets through horizontal continuous casting |
| CN101787456A (en) * | 2010-03-08 | 2010-07-28 | 南通汉瑞实业有限公司 | Production method of vanadium-nitrogen alloy |
| CN102002640A (en) * | 2010-09-09 | 2011-04-06 | 中国兵器工业第五二研究所 | Method for preparing high nitrogen steel by adopting pressurized induction |
| CN103451509A (en) * | 2013-08-22 | 2013-12-18 | 长春工业大学 | Method for smelting high-strength stainless steel |
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2013
- 2013-12-20 CN CN201310720215.6A patent/CN103710486B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1116241A (en) * | 1994-08-03 | 1996-02-07 | 宝山钢铁(集团)公司 | Producing technology of low hydrogen high nitrogen steel |
| KR20030030873A (en) * | 2001-10-11 | 2003-04-18 | 베들레헴 스틸 코포레이션 | A method for operating a steelmaking furnace during a steelmaking process |
| CN1563462A (en) * | 2004-03-18 | 2005-01-12 | 上海交通大学 | Method for smelting high nitrogen steel |
| CN101235461A (en) * | 2007-09-03 | 2008-08-06 | 北京科技大学 | Method for smelting high-nitrogen steel under normal pressure |
| CN201495269U (en) * | 2009-07-17 | 2010-06-02 | 廖大中 | Electroslag remelting furnace electrode and electroslag remelting furnace for smelting high nitrogen steels |
| CN101736121A (en) * | 2009-12-14 | 2010-06-16 | 衡阳华菱连轧管有限公司 | Method for smelting 07Cr2MoW2VNbB steel in electric furnace and using same to form round pipe billets through horizontal continuous casting |
| CN101787456A (en) * | 2010-03-08 | 2010-07-28 | 南通汉瑞实业有限公司 | Production method of vanadium-nitrogen alloy |
| CN102002640A (en) * | 2010-09-09 | 2011-04-06 | 中国兵器工业第五二研究所 | Method for preparing high nitrogen steel by adopting pressurized induction |
| CN103451509A (en) * | 2013-08-22 | 2013-12-18 | 长春工业大学 | Method for smelting high-strength stainless steel |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105710348A (en) * | 2014-12-01 | 2016-06-29 | 鞍钢股份有限公司 | Device and method for removing inclusions through refined bubbles |
| 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 |
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