CN106893795B - A kind of control globular inclusion smelts the process of ultra-clean steel - Google Patents
A kind of control globular inclusion smelts the process of ultra-clean steel Download PDFInfo
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- CN106893795B CN106893795B CN201710031701.5A CN201710031701A CN106893795B CN 106893795 B CN106893795 B CN 106893795B CN 201710031701 A CN201710031701 A CN 201710031701A CN 106893795 B CN106893795 B CN 106893795B
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- 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
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
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- 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
- C21C5/35—Blowing from above and through the bath
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- 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
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
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- 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
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
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- 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
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/072—Treatment with gases
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- 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
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
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Abstract
The invention discloses the processes that a kind of control globular inclusion smelts ultra-clean steel, include the following steps：KR desulfurizing irons：Using KR stirring desulphurizations, ensure S≤20ppm in the molten iron of stokehold；Top and bottom combined blown converter blows：Using specification 100T top and bottom combined blown converter smeltings, ensure the mass percent ω [C] >=0.10% of the C of tapping；Long-time external refining：For refining time in the range of 40~150min, whole process uses weak stirring, and for stirring argon flow amount in the range of 100~800NL/min, the mass percent ω [Al] of control refining bull ladle Al is in the range of 0.030%~0.050%；RH is vacuum-treated for a long time：The time of RH processing is in the range of 25~40min；Molten steel is stood after soft blow.By the method for the present invention it is found that taking a series of means removal steel inclusions again after reducing rapidly the free oxygen of molten steel using strong deoxidation of tapping, it is suitable for the production of different carbon content steel grades.
Description
Technical field
The present invention relates to a kind of fields of the process for making in steel industry, and in particular to a kind of control globular inclusion smelting
Refine the process of ultra-clean steel.
Background technology
One of the main reason for steel workpieces fatigue rupture is failure, and nonmetallic inclusionsin steel can often split as fatigue
The origin of line, similar sizes it is all types of be mingled with can line up dotted oxide ＞ string-like oxide ＞ strips by harmfulness size
The order of oxide ＞ strip sulfide.The spherical indeformable size that is mingled with is bigger, endangers fatigue life bigger.GB/T 10561
Ranking method individually grades the single globular inclusion for exceeding 13 μm in steel, and 0.5~3.0 grade is chosen as according to size.Steel
Middle total oxygen demand T.O has codetermined Cleanliness of Molten Steel with inclusion size, quantity, reduces T.O in steel as possible, reduces field trash ruler
The very little Main way that high-level clean steel is always produced with quantity.In steelmaking process, deoxygenation refining, there is deoxidant elements-
Dissolved oxygen, steel-slag, the reaction of molten steel-field trash and balance in steel, refining process top slag ingredient are controlled for steel inclusion
Quantity, composition and form have great influence.
The research of country's globular inclusion control technological measure is concentrated mainly on a small number of high-carbon such as high-carbon-chromium bearing steel at present
On steel, and C content is higher, and T.O, globular inclusion control aspect have apparent excellent in steel because first furnace is tapped for such steel grade
Gesture, such as a kind of smelting process of the patent CN104087719A high carbon bearing steel announced, can by T.O controls in steel 7ppm with
Under, and can effectively control D near-sphericals and be mingled with, but its control technique is only limitted to high carbon bearing steel.And the cleaning generally used at present
Steel production method focuses on molten steel T.O controls more, and controlled level is not high, few to control technique to globular inclusion in steel
Research only can guarantee molten steel if patent CN101525679 discloses a kind of clean steel production method reducing molten steel total oxygen content
T.O≤15ppm, and fail effectively to control globular inclusion in steel, Ds gradings can reach 1.0 grades.
Invention content
It is an object of the invention to：Overcome the deficiencies of the prior art and provide a kind of control globular inclusion smelting super clean
The process of steel, reduces rapidly to take again in a series of means removal steel after the free oxygen of molten steel and is mingled with using the strong deoxidation of tapping
Object is suitable for the production of different carbon content steel grades；Using superhigh-alkalinity high-alumina refining slag system, the good stream of clinker ensure that
The ability that dynamic property is mingled with deoxidation, absorption, reduces slugging fluorite dosage, and the quick deoxidation of energy simultaneously alleviates globular inclusion generation
Trend；It ensure that the floating removal time of deoxidation products and avoid the more additional molten steel generated due to smelting for a long time because crossing secondary
Pollution improves Molten Steel Cleanliness；It defines specific stirring argon flow amount, avoids the excessive secondary oxidation of liquid steel refining process, reduce
Additional oxygen source；Longer RH processing times are taken, remove steel inclusion as far as possible, using after treatment soft blow and molten steel
The method being combined is stood, removal efficiency of the inclusion is significantly improved；By the production practices of high-carbon steel, medium carbon steel and mild steel,
Molten Steel Cleanliness can be controlled in following level：T.O≤8.0ppm in steel, average content 6.0ppm；Item string is seldom found in steel
Shape field trash oxide, rank≤0.5 grade（20 μm of size ＜）；Do not find that the globular inclusion more than 10 μm, no Ds are mingled with.
The technical solution used in the present invention is：
A kind of control globular inclusion smelts the process of ultra-clean steel, includes the following steps：
1）KR desulfurizing irons：Using KR stirring desulphurizations, ensure S≤20ppm in the molten iron of stokehold；
2）Top and bottom combined blown converter blows：Using specification 100T top and bottom combined blown converter smeltings, ensure the quality percentage of the C of tapping
Than ω [C] >=0.10%；
3）Long-time external refining：For refining time in the range of 40~150min, whole process uses weak stirring, stirs argon gas
For flow in the range of 100~800NL/min, the mass percent ω [Al] of control refining bull ladle Al is 0.030%~0.050%
In the range of；
4）RH is vacuum-treated for a long time：The time of RH processing is in the range of 25~40min；
5）Molten steel is stood after soft blow：RH processing terminate carry out soft blow, the time of soft blow in the range of 8~15min, soft blow
Molten steel is stood after end, the time of standing is in the range of 30 ~ 35min.
The present invention is further improved scheme, the step 1）In, using the mass percent ω [S]≤0.035% of S
Molten iron is as raw material.
The further improvement project of the present invention is the step 2）In, before the 40t that taps, according to the ratio of 1.5~2.5kg/t
The quick deoxidation of aluminium cake is added in example, and the mass percent ω [Al] that control refines the Al that arrives at a station is 0.060%~0.090%.
The further improvement project of the present invention is the step 3）In, refining uses high alumina high alkalinity slag system, clinker binary
Basicity R2 is in the range of 15~25, Al2O3Mass percent in the range of 25%~40%.
The further improvement project of the present invention is the step 3）In, the ingredient of the high alumina high alkalinity slag system includes
CaO、SiO2、MgO、Al2O3, S and Tfe, the mass percent of each ingredient be：CaO：50%~60%, SiO2：2%~4%, MgO：4%
~8%, Al2O3：25%~40%, S：0.3%~1.5%, Tfe：0~0.5%.
The beneficial effects of the present invention are：
The first, a kind of control globular inclusion of the invention smelts the process of ultra-clean steel, using strong deoxidation of tapping
A series of means removal steel inclusions are taken again after reducing rapidly the free oxygen of molten steel, are suitable for the life of different carbon content steel grades
Production.
The second, a kind of control globular inclusion of the invention smelts the process of ultra-clean steel, using superhigh-alkalinity height
Aluminium oxide refining slag system ensure that the ability that the good mobility of clinker is mingled with deoxidation, absorption, reduce slugging fluorite use
Amount, the quick deoxidation of energy simultaneously alleviate globular inclusion generation trend.
A kind of process of control globular inclusion smelting ultra-clean steel of third, the present invention, ensure that deoxidation products
The floating removal time and the more additional molten steel secondary pollution that generates due to avoid smelting for a long time because crossing, raising molten steel it is pure
Degree.
4th, a kind of control globular inclusion of the invention smelts the process of ultra-clean steel, defines specific stirring
Argon flow amount avoids the excessive secondary oxidation of liquid steel refining process, reduces additional oxygen source.
5th, a kind of control globular inclusion of the invention smelts the process of ultra-clean steel, takes at longer RH
The time is managed, removes steel inclusion as far as possible, the method being combined is stood with molten steel using after treatment soft blow, is significantly carried
High removal efficiency of the inclusion.
6th, a kind of control globular inclusion of the invention smelts the process of ultra-clean steel, by high-carbon steel, middle carbon
The production practices of steel and mild steel, Molten Steel Cleanliness can be controlled in following level：T.O≤8.0ppm in steel, average content are
6.0ppm；A string-like field trash oxide, rank≤0.5 grade are seldom found in steel（20 μm of size ＜）；It does not find more than 10 μm
Globular inclusion, no Ds is mingled with.
Specific implementation mode
For the technique of medium carbon steel
42CrMo, the mass percent ω [C] of C is 0.42% in steel, using desulfurizing iron → LD → LF → RH technological processes
Production.It specifically includes following steps：
1）Molten iron using the mass percent ω [S]≤0.035% of S enters stokehold as raw material using KR stirring desulphurizations
Molten iron S≤20ppm；
2）Using specification 100T top and bottom combined blown converter smeltings, the mass percent ω [C] for the C that taps is 0.10%~0.15%
In range, the quick deoxidation of aluminium cake is added according to the proportional region of 1.6~1.9kg/t before the 40t that taps, refines the quality hundred for the Al that arrives at a station
Divide than ω [Al] in the range of 0.065%~0.080%；
3）Finishing slag basicity R2 is refined in the range of 15.08~22.68, the mass percent of each ingredient（wt%）For：CaO：
54.8%~59.43%, SiO2：2.62%~3.82%, MgO：4.08%~6.88%, Al2O3：27.3%~37.03%, S：0.305%
~0.848%, Tfe：0. 33%~0.47%；
4）For refining time within the scope of 80~110min, early period is stirred argon flow amount in 600NL/min~800NL/ in refining
In the range of min, refining mid-term stirs argon flow amount in the range of 400NL/min~600NL/min, and the refining later stage stirs argon
Throughput in the range of 100NL/min~300NL/min, the mass percent ω [Al] of refining bull ladle Al 0.033%~
In the range of 0.049%；
5）RH processing times in the range of 28~35min, the soft blow time in the range of 8~12min, molten steel stand when
Between be 30min.
By step 1）~step 5）In the 42CrMo steel of gained, T.O is maximum dotted in the range of 5.0~7.8ppm
For inclusion size in the range of 7~10 μm, maximum string, strip inclusion size are in the range of 10~18 μm.
Embodiment 1
42CrMo, the mass percent ω [C] of C is 0.42% in steel, using desulfurizing iron → LD → LF → RH technological processes
Production.It specifically includes following steps：
1）The mass percent ω [S] of S is used to enter stokehold using KR stirring desulphurizations as raw material for 0.031% molten iron
Molten iron S is 14ppm；
2）Using specification 100T top and bottom combined blown converter smeltings, the mass percent ω [C] for the C that taps is 0.13%, and tap 40t
The quick deoxidation of aluminium cake is added in the preceding ratio according to 1.7kg/t, and the mass percent ω [Al] for refining the Al that arrives at a station is 0.069%；
3）It is 19.24 to refine finishing slag basicity R2, the mass percent of each ingredient（wt%）For：CaO：55.22%、SiO2：
2.87%、MgO：5.28%、Al2O3：35.7%、S：0. 55%、Tfe：0.38%；
4）Refining time 90min, refining stirring early period argon flow amount are 780NL/min, and refining mid-term stirs argon flow amount
For 530NL/min, refining later stage stirring argon flow amount is 240NL/min, and the mass percent ω [Al] of refining bull ladle Al is
0.037%；
5）RH processing times are 32min, and the soft blow time is 11min, and molten steel time of repose is 30min；
By step 1）~step 5）In the 42CrMo steel of gained, T.O 7.3ppm, maximum dotted inclusion size is 9 μ
M, maximum string, strip inclusion size are 16 μm.
Embodiment 2
42CrMo, the mass percent ω [C] of C is 0.42% in steel, using desulfurizing iron → LD → LF → RH technological processes
Production.It specifically includes following steps：
1）The mass percent ω [S] of S is used to enter stokehold using KR stirring desulphurizations as raw material for 0.034% molten iron
Molten iron S is 17ppm.
2）Using specification 100T top and bottom combined blown converter smeltings, the mass percent ω [C] for the C that taps is 0.14%, and tap 40t
The quick deoxidation of aluminium cake is added in the preceding ratio according to 1.8kg/t, and the mass percent ω [Al] for refining the Al that arrives at a station is 0.073%.
3）It is 16.18 to refine finishing slag basicity R2, the mass percent of each ingredient（wt%）For：CaO：55.34%、SiO2：
3.42%、MgO：5.41%、Al2O3： 35.03%、S：0.38%、Tfe：0. 42%.
4）Refining time 100min, refining stirring early period argon flow amount are 730NL/min, and refining mid-term stirs argon flow amount
For 480NL/min, refining later stage stirring argon flow amount is 190NL/min, and refining bull ladle Al content is 0.043%.
5）RH processing times are 34min, and the soft blow time is 11min, and molten steel time of repose is 30min.
By step 1）~step 5）In the 42CrMo steel of gained, T.O 6.7ppm, maximum dotted inclusion size is 8 μ
M, maximum string, strip inclusion size are 14 μm.
Embodiment 3
42CrMo, the mass percent ω [C] of C is 0.42% in steel, using desulfurizing iron → LD → LF → RH technological processes
Production.It specifically includes following steps：
1）The mass percent ω [S] of S is used to enter stokehold using KR stirring desulphurizations as raw material for 0.032% molten iron
Molten iron S is 15ppm；
2）Using specification 100T top and bottom combined blown converter smeltings, the mass percent ω [C] for the C that taps is 0.13%, and tap 40t
The quick deoxidation of aluminium cake is added in the preceding ratio according to 1.8kg/t, and the mass percent ω [Al] for refining the Al that arrives at a station is 0.075%；
3）It is 19.36 to refine finishing slag basicity R2, the mass percent of each ingredient（wt%）For：CaO：57.51%、SiO2：
2.97%、MgO：6.08%、Al2O3：32. 5%、S：0.48%、Tfe：0. 46%；
4）Refining time 95min, refining stirring early period argon flow amount are 690NL/min, and refining mid-term stirs argon flow amount
For 470NL/min, refining later stage stirring argon flow amount is 230NL/min, and the mass percent ω [Al] of refining bull ladle Al is
0.039%；
5）RH processing times are 31min, and the soft blow time is 9min, and molten steel time of repose is 30min.
By step 1）~step 5）In the 42CrMo steel of gained, T.O 6.2ppm, maximum dotted inclusion size is 8 μ
M, maximum string, strip inclusion size are 17 μm.
For the technique of mild steel
SCM420H, the mass percent ω [C] of C is 0.20% in steel, using desulfurizing iron → LD → LF → RH technique streams
Journey produces.It specifically includes following steps：
1）Molten iron using the mass percent ω [S]≤0.035% of S enters stokehold as raw material using KR stirring desulphurizations
Molten iron S≤10ppm；
2）Using specification 100T top and bottom combined blown converter smeltings, the mass percent ω [C] for the C that taps is 0.10%~0.13%
In range, the quick deoxidation of aluminium cake is added according to the proportional region of 1.8~2.3kg/t before the 40t that taps, refines the quality hundred for the Al that arrives at a station
Divide than ω [Al] in the range of 0.071%~0.086%；
3）Finishing slag basicity R2 is refined in the range of 15.23~24.38, the mass percent of each ingredient（wt%）For：CaO：
54.36%~58.93%, SiO2：2.32%~3.58%, MgO：4.14%~5.08%, Al2O3：28.04%~38.29%, S：0.41%
~0.735%, Tfe：0. 21%~0.50%；
4）For refining time within the scope of 86~137min, early period is stirred argon flow amount in 500NL/min~800NL/ in refining
In the range of min, refining mid-term stirs argon flow amount in the range of 350NL/min~650NL/min, and the refining later stage stirs argon
Throughput in the range of 70NL/min~250NL/min, the mass percent ω [Al] of refining bull ladle Al 0.035%~
In the range of 0.050%；
5）RH processing times, the soft blow time, molten steel was stood in the range of 10~15min in the range of 28~38min
Time is 30min.
By step 1）~step 5）In the SCM420H steel of gained, T.O is maximum dotted in the range of 6.3~8.0ppm
For inclusion size in the range of 8~10 μm, maximum string, strip inclusion size are in the range of 13~20 μm.
Embodiment 4
SCM420H, the mass percent ω [C] of C is 0.20% in steel, using desulfurizing iron → LD → LF → RH technique streams
Journey produces.It specifically includes following steps：
1）The mass percent ω [S] of S is used to enter stokehold using KR stirring desulphurizations as raw material for 0.034% molten iron
Molten iron S is 8ppm；
2）Using specification 100T top and bottom combined blown converter smeltings, the mass percent ω [C] for the C that taps is 0.12%, and tap 40t
The quick deoxidation of aluminium cake is added in the preceding ratio according to 1.9kg/t, and the mass percent ω [Al] for refining the Al that arrives at a station is 0.079%；
3）It is 20.70 to refine finishing slag basicity R2, the mass percent of each ingredient（wt%）For：CaO：56.51%、SiO2：2.
73%、MgO：4.58%、Al2O3：35. 2%、S：0.62%、Tfe：0. 36%；
4）Refining time 125min, refining stirring early period argon flow amount are 620NL/min, and refining mid-term stirs argon flow amount
For 440NL/min, refining later stage stirring argon flow amount is 160NL/min, and the mass percent ω [Al] of refining bull ladle Al is
0.042%；
5）RH processing times are 34min, and the soft blow time is 13min, and molten steel time of repose is 30min.
By step 1）~step 5）In the SCM420H steel of gained, T.O 6.8ppm, maximum dotted inclusion size is
10 μm, maximum string, strip inclusion size are 15 μm.
Embodiment 5
SCM420H, the mass percent ω [C] of C is 0.20% in steel, using desulfurizing iron → LD → LF → RH technique streams
Journey produces.It specifically includes following steps：
1）The mass percent ω [S] of S is used to enter stokehold using KR stirring desulphurizations as raw material for 0.032% molten iron
Molten iron S is 7ppm；
2）Using specification 100T top and bottom combined blown converter smeltings, the mass percent ω [C] for the C that taps is 0.11%, and tap 40t
The quick deoxidation of aluminium cake is added in the preceding ratio according to 2.1kg/t, and the mass percent ω [Al] for refining the Al that arrives at a station is 0.083%；
3）It is 20.87 to refine finishing slag basicity R2, the mass percent of each ingredient（wt%）For：CaO：54.67%、SiO2：2.
62%、MgO：4.36%、Al2O3：37.46%、S：0.47%、Tfe：0. 42%；
4）Refining time 110min, refining stirring early period argon flow amount are 700NL/min, and refining mid-term stirs argon flow amount
For 530NL/min, refining later stage stirring argon flow amount is 200NL/min, and the mass percent ω [Al] of refining bull ladle Al is
0.047%；
5）RH processing times are 35min, and the soft blow time is 12min, and molten steel time of repose is 30min.
By step 1）~step 5）In the SCM420H steel of gained, T.O 6.4ppm, maximum dotted inclusion size is 8
μm, maximum string, strip inclusion size are 15 μm.
Embodiment 6
SCM420H, the mass percent ω [C] of C is 0.20% in steel, using desulfurizing iron → LD → LF → RH technique streams
Journey produces.It specifically includes following steps：
1）The mass percent ω [S] of S is used to enter stokehold using KR stirring desulphurizations as raw material for 0.030% molten iron
Molten iron S is 10ppm；
2）Using specification 100T top and bottom combined blown converter smeltings, the mass percent ω [C] for the C that taps is 0.10%, and tap 40t
The quick deoxidation of aluminium cake is added in the preceding ratio according to 2.0kg/t, and the mass percent ω [Al] for refining the Al that arrives at a station is 0.081%；
3）It is 20.84 to refine finishing slag basicity R2, the mass percent of each ingredient（wt%）For：CaO：55.63%、SiO2：
2.67%、MgO：4.43%、Al2O3：36. 4%、S：0.48%、Tfe：0.39%；
4）Refining time 120min, refining stirring early period argon flow amount are 720NL/min, and refining mid-term stirs argon flow amount
For 500NL/min, refining later stage stirring argon flow amount is 200NL/min, and the mass percent ω [Al] of refining bull ladle Al is
0.045%；
5）RH processing times are 34min, and the soft blow time is 12min, and molten steel time of repose is 30min.
By step 1）~step 5）In the SCM420H steel of gained, T.O 7.2ppm, maximum dotted inclusion size is 9
μm, maximum string, strip inclusion size are 17 μm.
For the technique of high-carbon steel
B2 steel, the mass percent ω [C] of C is 0.77% in steel, is given birth to using desulfurizing iron → LD → LF → RH technological processes
Production.It specifically includes following steps：
1）Molten iron using the mass percent ω [S]≤0.035% of S enters stokehold as raw material using KR stirring desulphurizations
Molten iron S≤10ppm；
2）Using specification 100T top and bottom combined blown converter smeltings, the mass percent ω [C] for the C that taps is 0.12%~0.20%
In range, the quick deoxidation of aluminium cake is added according to the proportional region of 1.6~1.9kg/t before the 40t that taps, refines the quality hundred for the Al that arrives at a station
Divide than ω [Al] in the range of 0.060%~0.075%；
3）Finishing slag basicity R2 is refined in the range of 16.02~23.94, the mass percent of each ingredient（wt%）For：CaO：
55.29%~60.00%, SiO2：2.32%~3.79%, MgO：4.06%~6.01%, Al2O3：25.33%~35.63%, S：0.58%
~1.2%, Tfe：0. 13%~0.42%；
4）For refining time within the scope of 67~108min, early period is stirred argon flow amount in 400NL/min~600NL/ in refining
In the range of min, refining mid-term stirs argon flow amount in the range of 500NL/min~750NL/min, and the refining later stage stirs argon
Throughput in the range of 150NL/min~350NL/min, the mass percent ω [Al] of refining bull ladle Al 0.030%~
In the range of 0.045%；
5）RH processing times in the range of 33~40min, the soft blow time in the range of 8~15min, molten steel stand when
Between be 30min.
By step 1）~step 5）In the B2 steel of gained, T.O is in the range of 4.8~7.0ppm, maximum Mechanism of Formation of The Globular Inclusions
For object size in the range of 5~8 μm, maximum string, strip inclusion size are in the range of 10~18 μm.
Embodiment 7
B2 steel, the mass percent ω [C] of C is 0.77% in steel, is given birth to using desulfurizing iron → LD → LF → RH technological processes
Production.It specifically includes following steps：
1）The mass percent ω [S] of S is used to enter stokehold using KR stirring desulphurizations as raw material for 0.033% molten iron
Molten iron S is 8ppm；
2）Using specification 100T top and bottom combined blown converter smeltings, the mass percent ω [C] for the C that taps is 0.15%, and tap 40t
The quick deoxidation of aluminium cake is added in the preceding ratio according to 1.7kg/t, and the mass percent ω [Al] for refining the Al that arrives at a station is 0.068%；
3）It is 19.53 to refine finishing slag basicity R2, the mass percent of each ingredient（wt%）For：CaO：58.98%、SiO2：
3.02%、MgO：4.96%、Al2O3：31. 9%、S：0.91%、Tfe：0.23%；
4）Refining time 90min, refining stirring early period argon flow amount are 500NL/min, and refining mid-term stirs argon flow amount
For 610NL/min, refining later stage stirring argon flow amount is 270NL/min, and the mass percent ω [Al] of refining bull ladle Al is
0.039%；
5）RH processing times are 36min, and the soft blow time is 12min, and molten steel time of repose is 30min.
By step 1）~step 5）In the B2 steel of gained, T.O 6.2ppm, maximum dotted inclusion size is 6 μm, most
Big string, strip inclusion size are 14 μm.
Embodiment 8
B2 steel, the mass percent ω [C] of C is 0.77% in steel, is given birth to using desulfurizing iron → LD → LF → RH technological processes
Production.It specifically includes following steps：
1）The mass percent ω [S] of S is used to enter stokehold using KR stirring desulphurizations as raw material for 0.030% molten iron
Molten iron S is 5ppm；
2）Using specification 100T top and bottom combined blown converter smeltings, the mass percent ω [C] for the C that taps is 0.18%, and tap 40t
The quick deoxidation of aluminium cake is added in the preceding ratio according to 1.6kg/t, and the mass percent ω [Al] for refining the Al that arrives at a station is 0.071%；
3）It is 16.52 to refine finishing slag basicity R2, the mass percent of each ingredient（wt%）For：CaO：57.31%、SiO2：
3.47%、MgO：5. 61%、Al2O3：32. 3%、S：1.04%、Tfe：0.27%；
4）Refining time 90min, refining stirring early period argon flow amount are 480NL/min, and refining mid-term stirs argon flow amount
For 650NL/min, refining later stage stirring argon flow amount is 280NL/min, and the mass percent ω [Al] of refining bull ladle Al is
0.041%；
5）RH processing times are 38min, and the soft blow time is 13min, and molten steel time of repose is 30min.
By step 1）~step 5）In the B2 steel of gained, T.O 5.9ppm, maximum dotted inclusion size is 7 μm, most
Big string, strip inclusion size are 15 μm.
Embodiment 9
B2 steel, the mass percent ω [C] of C is 0.77% in steel, is given birth to using desulfurizing iron → LD → LF → RH technological processes
Production.It specifically includes following steps：
1）The mass percent ω [S] of S is used to enter stokehold using KR stirring desulphurizations as raw material for 0.031% molten iron
Molten iron S is 6ppm；
2）Using specification 100T top and bottom combined blown converter smeltings, the mass percent ω [C] for the C that taps is 0.17%, and tap 40t
The quick deoxidation of aluminium cake is added in the preceding ratio according to 1.7kg/t, and the mass percent ω [Al] for refining the Al that arrives at a station is 0.070%；
3）It is 17.89 to refine finishing slag basicity R2, the mass percent of each ingredient（wt%）For：CaO：57.78%、SiO2：
3.23%、MgO：5.35%、Al2O3：32.4%、S：0.98%、Tfe：0.26%；
4）Refining time 95min, refining stirring early period argon flow amount are 530NL/min, and refining mid-term stirs argon flow amount
For 680NL/min, refining later stage stirring argon flow amount is 240NL/min, and the mass percent ω [Al] of refining bull ladle Al is
0.043%；
5）RH processing times are 35min, and the soft blow time is 12min, and molten steel time of repose is 30min.
By step 1）~step 5）In the B2 steel of gained, T.O 5.8ppm, maximum dotted inclusion size is 6 μm, most
Big string, strip inclusion size are 15 μm.
Claims (4)
1. a kind of control globular inclusion smelts the process of ultra-clean steel, it is characterised in that include the following steps：
1）KR desulfurizing irons：Using KR stirring desulphurizations, ensure S≤20ppm in the molten iron of stokehold；
2）Top and bottom combined blown converter blows：Using specification 100t top and bottom combined blown converter smeltings, ensure the mass percent of the C of tapping
Before ω [C] >=0.10%, the 40t that taps, the quick deoxidation of aluminium cake is added according to the ratio of 1.5~2.5kg/t, control refines the Al that arrives at a station
Mass percent ω [Al] be 0.060%~0.090%；
3）Long-time external refining：For refining time in the range of 40~150min, whole process uses weak stirring, stirs argon flow amount
In the range of 100~800NL/min, control refines models of the mass percent ω [Al] of bull ladle Al 0.030%~0.050%
In enclosing；
4）RH is vacuum-treated for a long time：The time of RH processing is in the range of 25~40min；
5）Molten steel is stood after soft blow：RH processing terminates to carry out soft blow, and the time of soft blow, soft blow terminated in the range of 8~15min
Molten steel is stood later, the time of standing is in the range of 30 ~ 35min.
2. a kind of control globular inclusion as described in claim 1 smelts the process of ultra-clean steel, it is characterised in that：Institute
State step 1）In, using S mass percent ω [S]≤0.035% molten iron as raw material.
3. a kind of control globular inclusion as described in claim 1 smelts the process of ultra-clean steel, it is characterised in that：Institute
State step 3）In, refining uses high alumina high alkalinity slag system, and clinker dual alkalinity R2 is in the range of 15~25, Al2O3Quality hundred
Divide ratio in the range of 25%~40%.
4. a kind of control globular inclusion as claimed in claim 3 smelts the process of ultra-clean steel, it is characterised in that：Institute
State step 3）In, the ingredient of the high alumina high alkalinity slag system includes CaO, SiO2、MgO、Al2O3, S and TFe, the quality of each ingredient
Percentage is：CaO：50%~60%, SiO2：2%~4%, MgO：4%~8%, Al2O3：25%~40%, S：0.3%~1.5%, TFe：
0~0.5%。
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