CN100540705C - The method of smelting ferritic stainless steel from total molten iron - Google Patents

The method of smelting ferritic stainless steel from total molten iron Download PDF

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Publication number
CN100540705C
CN100540705C CNB2004100990775A CN200410099077A CN100540705C CN 100540705 C CN100540705 C CN 100540705C CN B2004100990775 A CNB2004100990775 A CN B2004100990775A CN 200410099077 A CN200410099077 A CN 200410099077A CN 100540705 C CN100540705 C CN 100540705C
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oxygen
stainless steel
molten iron
steel
decarburization
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CNB2004100990775A
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CN1796585A (en
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池和冰
江庆元
史金强
张海清
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Baoshan Iron and Steel Co Ltd
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Shanghai First Iron & Steel Co Ltd Baogang Group
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Abstract

The method of smelting ferritic stainless steel from total molten iron comprises the steps: that a. smelts, process temperature control, and blowing speed in early stage is elevated to 1580～1600 ℃ with bath temperature, and the ferrosilicon that adds 4～15kg/ ton steel heats up; Simultaneously, at this control decarbonization rate, decarbonization rate is controlled at 0.09～0.12% in stage/minute; B. when the molten bath is warmed up to 1670～1720 ℃, begin to add ferrochrome, 2～3 tons/minute, the ferrochrome add-on is 250～280kg/ ton steel, keeps bath temperature stable; C. decarburization, when decarburization finishes, [C]=0.03%～0.05%, temperature is controlled at 1700～1730 ℃; D. reduction and desulfurization then.The present invention adopts overall height stove molten iron smelting, has avoided the influence of impure steel scrap; Because the technology that adopts AOD directly to smelt, mother liquor of stainless steel that need not electrosmelting is produced cost decline significantly.

Description

The method of smelting ferritic stainless steel from total molten iron
Technical field
The invention belongs to the stainless steel-making process field.
Background technology
Adopt traditional technology to be in the stainless steel smelting field at present: EAF+AOD+ (VOD), adopt steel scrap+alloy to be fused into the mother liquor of stainless steel (slightly make steel water) of certain temperature and composition at EAF, again mother liquor of stainless steel (slightly make steel water) is dropped in the AOD stove and carries out refining.
Existing former ferritic stainless steel smelting technology flow process is:
Steel scrap (hot metal charging) → electrosmelting → AOD refining → (VOD refining) → continuous casting
Wherein, AOD refinery practice:
Mother liquor composition: C 1.0%～3.0%, Mn 0～0.2%, and Si 0～0.2%, and S 0～0.020%, P0～0.030%, Cr 13.0%～14.0%, and Ni 0～0.5%; The mother liquor temperature: 1500～1580 ℃, 110～115 tons of mother liquor weight.
The AOD smelting technology:
The electric furnace mother liquor is blended into the AOD converter, measures the mother liquor temperature, blow by oxygen supply, the air feed standard of table 1 regulation blowing pattern.
Table 1
Nm 3/min
Stage Si, Al oxidation Main blowing Dynamic 1 Dynamic 2 Dynamic 3 Reduction Desulfurization
Oxygen-supplying amount Nm 3 1000 4800 5200 5400 5500
Top rifle O 2Flow 120 120 0 0 0 0 0
Air port O 2Flow 90 90 60 40 30 0 0
Air port N 2Flow 30 30 60 80 0 0 0
Air port Ar flow 0 0 0 0 110 110 110
I) reach 3000Nm at blowing oxygen quantity 3The remaining Cr-Fe of Shi Peijia,
Ii) when blowing oxygen quantity reaches whole oxygen-supplying amounts and finishes decarburization, add reductive agent ferrosilicon 20～25kg/t and carry out restoring operation,
Iii) reduction is carried out desulfurization operations after finishing, and the lime of adding 10～15kg/ ton steel, the fluorite of 6～10kg/ ton steel carry out desulfurization.
Iv) carry out molten steel component fine setting, tap after meeting ingredient standard.
The AOD molten steel component of tapping:
C 0.030%～0.080%, and Mn 0.20%～0.60%, and Si 0.20%～0.50%, S0.001%～0.010%, P0～0.035%, Cr16.0%～16.5%, Ni0～0.5%, Mo0～0.5%, N 0～450ppm; Tapping liquid steel temperature: 1630～1680 ℃.
Former smelting technology must adopt furnace melting steel scrap, alloy and partial molten iron, on technology also is feasible, but there is the quite high shortcoming of power consumption with smelting mother liquor of stainless steel from electric furnace, electric power consumption per ton steel is 320～360kwh, has correspondingly increased production cost, in addition, electric furnace production must blowing out be carried out the refractory materials maintenance after 7～10 days, need to stop production 10～24 hours, the whole piece stainless steel production line must stop production 10～24 hours like this, and the production production capacity is subjected to very big influence.
Summary of the invention
The object of the present invention is to provide a kind of method of AOD smelting ferritic stainless steel from total molten iron, skip the EAF operation, adopt blast-melted (behind the dephosphorization)+alloy in the AOD stove, directly to smelt ferritic stainless steel.
For achieving the above object, technical solution of the present invention is: the method for smelting ferritic stainless steel from total molten iron, comprise the steps,
A. smelt, process temperature control, blowing speed in early stage is elevated to 1580～1600 ℃ with bath temperature, and the ferrosilicon that adds 4～15kg/ ton steel heats up; Simultaneously, at this control decarbonization rate, decarbonization rate is controlled at 0.09～0.12% in stage/minute;
B. when the molten bath is warmed up to 1670～1720 ℃, begin to add ferrochrome, 2～3 tons/minute, the ferrochrome add-on is 250～280kg/ ton steel, keeps bath temperature stable;
C. decarburization, when decarburization finishes, [C]=0.03%～0.05%, temperature is controlled at 1700～1730 ℃;
D. reduction when blowing oxygen quantity reaches whole oxygen-supplying amounts and finishes decarburization, adds reductive agent ferrosilicon 20～25kg/t and carries out restoring operation;
E. desulfurization, reduction is carried out desulfurization operations after finishing, and the lime, the 6～10kg/ ton steel fluorite that add 10～15kg/ ton steel carry out desulfurization.Carry out molten steel component fine setting, tap after meeting ingredient standard.
Wherein, oxygen-supplying amount control in the described smelting process: the ratio control of oxygen and rare gas element:
I) in Si, Al oxidation blowing stage, oxygen-supplying amount is less than 6Nm 3During/t, air port oxygen and rare gas element ratio control were at 3.5: 1;
Ii) in the main decarburization blowing stage, oxygen-supplying amount is 6～60Nm 3During/t, air port oxygen and rare gas element ratio control are 3.5: 1;
Iii) in dynamic 1 stage of decarburization, oxygen-supplying amount is 60～63Nm 3During/t, air port oxygen and rare gas element ratio control are 1: 1;
Iv) in dynamic 2 stages of decarburization, oxygen-supplying amount is 63～66Nm 3During/t, air port oxygen and rare gas element ratio control are 1: 2;
V) in dynamic 3 stages of decarburization, oxygen-supplying amount is 66～70Nm 3During/t, air port oxygen and rare gas element ratio control are 1: 3.
Wherein, the accumulative total oxygen-supplying amount is 68～70Nm 3/ t.
Oxygen-supplying amount reaches 30～33Nm 3During/t, begin to add ferrochrome, 2～3 tons/minute, keep bath temperature stable.
It is that the oxidation of controlling chromium drops to minimum level that oxygen and rare gas element ratio are rationally controlled purpose, improves the recovery rate of chromium metal.
The invention has the advantages that:
1. impurity element control
Adopt overall height stove molten iron smelting, avoided stainless molten steel to be subjected to the quality influence of impure steel scrap, the trace element that Cu, Ni, Sn, Pb, As etc. have a significant effect to the stainless steel quality can be controlled in the extremely low scope, even can ignore, greatly reduce the difficulty of smelting high cleanliness 400 series stainless steels.
2.N control
Because molten iron [C] content height, the N that increases of violent C-O reaction significantly minimizing molten steel measures, and smelting that need not be special is controlled, and can smelt 400 series stainless steels of [N]≤300ppm.
3.[P] control
Because do not have the pollution of steel scrap, finished product [P] can reach below 0.020% more like a cork.The super stainless steel that adopts technology of the present invention to smelt [P]≤0.010% also will become than easier in the past.
4. cost advantage
Because the technology that adopts AOD directly to smelt, mother liquor of stainless steel that need not electrosmelting (slightly make steel water) in common process, will be saved by the cost of electric furnace generation like this.
Electric energy saving, power shortages now, its generation be not only the direct economic benefit of enterprise just.The saving of the furnace lining cost of anti-the material, consumption such as goods, materials and equipments, equipment, electrode will be very considerable incomes.
Embodiment
Embodiment 1
The AOD smelting technology
Hot metal composition: C 4.0%～4.3%, Mn 0～0.20%, and Si 0～0.05%, and S 0～0.020%, P0～0.030%, Cr 0～0.5%, and Ni 0～0.5%:
Molten iron temperature: 1100～1300 ℃, weight of molten iron: 90～95 tons;
Molten iron is blended into the AOD converter, measures molten iron temperature, oxygen supply, the air feed standard stipulated by table 2 blowing pattern blow;
Opening the ferrosilicon intensification that adds 4～15kg/t steel when blowing, bath temperature is elevated to 1550～1600 ℃; Continuing oxygen decarburization heats up.
The accumulative total oxygen-supplying amount reaches 30～33Nm 3During/t, bath temperature begins to add ferrochrome for about 1670～1720 ℃, and short run successively adds (2～3 tons/minute), keeps bath temperature stable, adds ferrochrome 250～280kg/ ton steel altogether;
When blowing oxygen quantity reaches whole oxygen-supplying amounts and finishes decarburization, add reductive agent ferrosilicon 20～25kg/t and carry out restoring operation;
Reduction is carried out desulfurization operations after finishing, and the lime, the 6～10kg/ ton steel fluorite that add 10～15kg/ ton steel carry out desulfurization.
Carry out molten steel component fine setting, tap after meeting ingredient standard.
AOD molten steel component: the C 0.030%～0.080% that taps, Mn 0.20%～0.60%, Si0.20%～0.50%, S 0.001%～0.010%, P0～0.035%, Cr16.0%～16.5%, Ni0～0.5%, N0～450ppm; Tapping liquid steel temperature: 1630～1680 ℃.
Table 2
Nm 3/min
Stage Si, Al oxidation Main blowing Dynamic 1 Dynamic 2 Dynamic 3 Reduction Desulfurization
Oxygen-supplying amount Nm 3 800 6500 7200 8000 8200
Top rifle O 2Flow 0 100 100 0 0 0 0
Air port O 2Flow 110 110 110 60 30 0 0
Air port N 2Flow 30 30 30 60 0 0 0
Air port Ar flow 0 0 0 0 110 110 110
Embodiment 2
Hot metal composition: C 3.05%, Mn 0.05%, and Si 0.00%, and S 0.023%, and P 0.019%, Cr0.03%, Ni 0.01%;
Molten iron temperature: 1296 ℃, weight of molten iron: 91 tons;
Adding Si-Fe 488kg during the blowing beginning heats up;
Accumulative total reaches oxygen-supplying amount 3500Nm 3Beginning adds ferrochrome 32300kg continuously;
The blowing pattern sees Table 3:
Table 3
Nm 3/min
Stage Si, Al oxidation Main blowing Dynamic 1 Dynamic 2 Dynamic 3 Reduction Desulfurization
Oxygen-supplying amount Nm 3 700 7020 7520 7710 7845
Top rifle O 2Flow 0 140 0 0 0 0 0
Air port O 2Flow 110 110 60 40 30 0 0
Air port N 2Flow 30 30 60 80 110 0 0
Air port Ar flow 0 0 0 0 0 110 110
Molten steel composition when decarburization finishes:
C Mn Si S P Cr Ni N
0.030％ 0.07％ 0.01％ 0.019％ 0.026％ 14.37％ 0.09％ 600ppm
Liquid steel temperature when decarburization finishes: 1725 ℃;
Adding reductive agent ferrosilicon 2689kg reduces;
Reduction is carried out desulfurization operations after finishing, and the lime, the 1100kg fluorite that add 1500kg carry out desulfurization.
Go out composition of steel:
C Mn Si S P Cr Ni N
0.031％ 0.55％ 0.34％ 0.005％ 0.027％ 16.3％ 0.09％ 430ppm
Tapping liquid steel temperature: 1670 ℃ of tapping molten steel weight: 123 tons
Embodiment 3:
Hot metal composition:
C Mn Si S P Cr Ni
3.21％ 0.10％ 0.00％ 0.010％ 0.011％ 0.03％ 0.01％
Molten iron temperature: 1250 ℃, weight of molten iron: 90 tons
Adding Si-Fe 488kg during the blowing beginning heats up
Accumulative total reaches oxygen-supplying amount 3450Nm 3Beginning adds ferrochrome 32000kg continuously.
The blowing pattern sees Table 4:
Table 4
Nm 3/min
Stage Si, Al oxidation Main blowing Dynamic 1 Dynamic 2 Dynamic 3 Reduction Desulfurization
Oxygen-supplying amount Nm 3 700 7300 7800 7940 8090
Top rifle O 2Flow 0 140 0 0 0 0 0
Air port O 2Flow 110 110 60 40 30 0 0
Air port N 2Flow 30 30 60 80 110 0 0
Air port Ar flow 0 0 0 0 0 110 110
Molten steel composition when decarburization finishes:
C Mn Si S P Cr Ni N
0.029％ 0.10％ 0.02％ 0.020％ 0.021％ 14.47％ 0.10％ 560ppm
Liquid steel temperature when decarburization finishes: 1732 ℃
Adding reductive agent ferrosilicon 2699kg reduces;
Reduction is carried out desulfurization operations after finishing, and the lime, the 1200kg fluorite that add 1498kg carry out desulfurization.
Go out composition of steel:
C Mn Si S P Cr Ni N
0.030％ 0.50％ 0.33％ 0.009％ 0.020％ 16.37％ 0.10％ 420ppm
The tapping liquid steel temperature: 1670 ℃, tapping molten steel weight: 122 tons.
As everyone knows, adopt full molten iron smelting stainless steel, its thermal equilibrium control is very difficult and since this point worldwide smelting stainless steel all adopt mother liquor of stainless steel (slightly make steel water) that steel scrap becomes certain ingredients and temperature by furnace melting to carry out the technology of Decarburising and refining to AOD again.Even adopt blast-melted (behind the dephosphorization), also must and steel scrap collocation use and in electric furnace, be fused into mother liquor of stainless steel (slightly make steel water), carry out Decarburising and refining through AOD again.
The present invention has made full use of the blast-melted C of containing height, the characteristics that chemical heat is high, and stable control bath temperature in converting process is controlled at the oxidation of Cr in the small range, takes off C to greatest extent simultaneously, and the CRE value on average can reach more than 0.7.

Claims (6)

1. the method for smelting ferritic stainless steel from total molten iron comprises the steps,
A. smelt, process temperature control, blowing speed in early stage is elevated to 1580～1600 ℃ with bath temperature, and the ferrosilicon that adds 4～15kg/ ton steel heats up; Simultaneously, at this control decarbonization rate, decarbonization rate is controlled at 0.09～0.12% in stage/minute;
B. begin to add ferrochrome when the molten bath is warmed up to 1670 ℃～1720 ℃, adding speed is 2～3 tons/minute, and the ferrochrome add-on is 250～280kg/ ton steel, keeps bath temperature stable;
C. decarburization, when decarburization finishes, [C]=0.03%～0.05%, temperature is controlled at 1700 ℃～1730 ℃;
D. reduction adds the reductive agent ferrosilicon and reduces
E. desulfurization, adding lime, fluorite carry out desulfurization.
2. the method for smelting ferritic stainless steel from total molten iron as claimed in claim 1 is characterized in that, described carbon rejection process oxygen-supplying amount control, and the ratio control of oxygen and rare gas element:
I) in Si, Al oxidation blowing stage, oxygen-supplying amount is less than 6Nm 3During/t, air port oxygen and rare gas element ratio control were at 3.5: 1;
Ii) in the main decarburization blowing stage, oxygen-supplying amount is 6～60Nm 3During/t, air port oxygen and rare gas element ratio control are 3.5: 1;
Iii) in dynamic 1 stage of decarburization, oxygen-supplying amount is 60～63Nm 3During/t, air port oxygen and rare gas element ratio control are 1: 1;
Iv) in dynamic 2 stages of decarburization, oxygen-supplying amount is 63～66Nm 3During/t, air port oxygen and rare gas element ratio control are 1: 2;
V) in dynamic 3 stages of decarburization, oxygen-supplying amount is 66～70Nm 3During/t, air port oxygen and rare gas element ratio control are 1: 3.
3. the method for smelting ferritic stainless steel from total molten iron as claimed in claim 2 is characterized in that, the accumulative total oxygen-supplying amount is 68～70Nm 3/ t.
4. the method for smelting ferritic stainless steel from total molten iron as claimed in claim 2 is characterized in that, oxygen-supplying amount reaches 30～33Nm 3During/t, begin to add ferrochrome, adding speed is 2～3 tons/minute, keeps bath temperature stable.
5. the method for smelting ferritic stainless steel from total molten iron as claimed in claim 1 is characterized in that, in the described steps d reduction, adds reductive agent ferrosilicon 20～25kg/t and reduces.
6. the method for smelting ferritic stainless steel from total molten iron as claimed in claim 1 is characterized in that, adds the lime of 10～15kg/ ton steel in the described step e sweetening process, the fluorite of 6～10kg/ ton steel carries out desulfurization.
CNB2004100990775A 2004-12-27 2004-12-27 The method of smelting ferritic stainless steel from total molten iron Expired - Fee Related CN100540705C (en)

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Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101271095B (en) * 2007-03-19 2010-06-09 宝山钢铁股份有限公司 Method for detecting scrap steel constituent in stainless steel
CN101519709B (en) * 2008-02-26 2011-01-19 宝山钢铁股份有限公司 Gas supply method in high-carbon regions during smelting stainless steel by AOD furnace
CN103146981B (en) * 2013-03-08 2014-12-24 山西太钢不锈钢股份有限公司 Method for smelting ferritic stainless steel by dephosphorized molten iron
CN103184314A (en) * 2013-03-12 2013-07-03 邢台钢铁有限责任公司 Smelting method for dephosphorization of hot metal in AOD furnace
CN107130188B (en) * 2017-04-07 2019-02-19 邢台钢铁有限责任公司 Welding ferritic stainless steel and its method for refining
CN112280935A (en) * 2020-09-27 2021-01-29 甘肃酒钢集团宏兴钢铁股份有限公司 Steelmaking deoxidizer produced from photovoltaic material powder and preparation method thereof

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