CN109182639A - A method of improving the high-strength automotive frame steel cleanness of 420MPa under no Calcium treatment process conditions - Google Patents
A method of improving the high-strength automotive frame steel cleanness of 420MPa under no Calcium treatment process conditions Download PDFInfo
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- CN109182639A CN109182639A CN201811068658.0A CN201811068658A CN109182639A CN 109182639 A CN109182639 A CN 109182639A CN 201811068658 A CN201811068658 A CN 201811068658A CN 109182639 A CN109182639 A CN 109182639A
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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
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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
- C21C7/072—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 a kind of methods that the high-strength automotive frame steel cleanness of 420MPa is improved under no Calcium treatment process conditions.The following steps are included: molten iron pre-processes；Top and bottom combined blown converter smelting；Argon is stood firm oxygen；The refining of LF furnace；The refining of RH furnace, accurate adjustment chemical component to target zone；After RH vacuum breaker, opens steel ladle bottom argon blowing and molten steel is stirred only；Slab caster is cast on molten steel.Cleanliness of Molten Steel can be improved by not needing progress Calcium treatment, it is very big to Ca recovery rate fluctuation caused by molten steel progress Calcium treatment operation in the process to avoid the high-strength beam steel LF refining of 420MPa, line feeding amount or calcium alloy additional amount are difficult to determining, Calcium treatment process chemistry reaction acutely, steel slag splash is big, secondary oxidation of steel is serious and molten steel in the drawbacks such as oxidizable element al, Ti decaying be big, improve Cleanliness of Molten Steel under no Calcium treatment process conditions.
Description
Technical field
The invention belongs to make steel smelting process technical field, and in particular to improve under a kind of no Calcium treatment process conditions
The method of the high-strength automotive frame steel cleanness of 420MPa.
Background technique
Automobile frame is subject to the important component of load, it to bear the weight of automobile itself components, loading capacity and
When driving the effects of suffered impact, distortion, inertia force, to improve vehicle frame bearing capacity and ensuring the peace of vehicle heavy duty enforcement
Quan Xing, while automobile factory requires to meet downstream user to the heavy duty of vehicle, heavy and medium truck stringer mostly uses at present
Lengthening beam and " double crossbeams " structure-i.e. " main longitudinal grider+reinforcing beam " formula vehicle frame.In order to reduce car weight, each automaker is to height
The demand of strength automotive beam steel plate is continuously increased, and each iron and steel enterprise also goes with the tide of historical development, and it is big constantly to develop new automobile
Hot-rolled steel sheet.
Currently, in domestic STEELMAKING PRODUCTION, it is general using " molten iron pretreatment → top and bottom combined blown converter → alloy finely tunes station → LF
Furnace → sheet billet continuous casting " process flow is produced.It is deferrization water sulphur that molten iron, which pre-processes major function, and top and bottom combined blown converter function exists
In decarburization, heating；Alloy fine tuning station major function is uniform molten steel composition and temperature, and LF refining furnace major function is slag making, closes
Aurification, accurate adjustment liquid steel temperature, and Calcium treatment is carried out in the refining later period to improve molten steel cleaning to denaturation treatment is carried out in molten steel
Degree, sheet billet continuous casting major function is that molten steel is cast into continuous casting billet.
So-called Calcium treatment, i.e., to high-melting-point Al remaining in molten steel2O3It is mingled with carry out denaturation treatment, forms the calcium of low melting point
Aluminate improves the casting properties of molten steel with this.Currently, there are two types of the main means of Calcium treatment: the first, by ladle
It is inside directly added into calcium alloy, is blown the methods of calcium alloy into molten steel；Second, ladle feeds calcium line method, it is by calcium alloy
(Ca, Ca-Si, Ca-Fe etc.) is wrapped up with sheetmetal and core-spun yarn is made, and is inserted into it with very high speed by the guide wire of wire feeder
Molten steel is stirred using steel ladle bottom argon blowing, promotes the progress of metallurgical reaction, by Al2O3Brittle inclusion becomes the calcium aluminic acid of low melting point
Salt ball-type is mingled with, and effectively facilitates the floating of field trash, improves the cleanliness of molten steel, can mitigate clogging of tundish nozzle problem,
Realize that low overheat casting creates conditions for continuous casting, stable prod performance.
If without Calcium treatment, remaining high-melting-point Al in molten steel2O3It is mixed in continuous casting casting process and is easy blocking crystallizer
Slag entrapment in mold, the disorder of crystallizer flow field are caused in the mouth of a river, be easy to cause back molten steel, continuous casting it is unplanned stop pouring, the production such as substandard products and
Quality accident.Therefore, steel mill generallys use Calcium treatment production 420MPa hot-rolled structural steel at present.
Cleanliness of Molten Steel can be effectively improved using Calcium treatment technique, but have the following disadvantages: 1. to ladle feeding line or
It is added during calcium alloy, due to calcium low boiling point, is easy gasification, cause the fluctuation of Ca recovery rate very big, line feeding amount or calcium alloy add
Enter amount to be difficult to determine；2. to ladle feeding line or add calcium alloy during, reaction acutely, molten steel splash is serious, meanwhile, molten steel with
Air largely contacts, and secondary oxidation is serious, element al easy to oxidize in molten steel, Ti decaying is caused, to influence Cleanliness of Molten Steel
And properties of product；3. core-spun yarn, calcium alloy need outsourcing, and its quality is very different, is unfavorable for steel mill's control cost.
Summary of the invention
In order to solve the above technical problems, the present invention provides improve the high-strength vapour of 420MPa under a kind of no Calcium treatment process conditions
The method of crossbeam steel cleanness.Cleanliness of Molten Steel can be improved by not needing progress Calcium treatment, avoid the high-strength automobile of 420MPa
Ca recovery rate caused by Calcium treatment operation is carried out to molten steel during beam steel LF refining and fluctuates very big, line feeding amount or calcium alloy
Additional amount is difficult to determine, the reaction of Calcium treatment process chemistry acutely, steel slag splash is big, secondary oxidation of steel is serious and molten steel in easy oxygen
Change the drawbacks such as element al, Ti decaying be big, improves Cleanliness of Molten Steel under no Calcium treatment process conditions.
The technical scheme adopted by the invention is as follows:
A method of improving the high-strength automotive frame steel cleanness of 420MPa under no Calcium treatment process conditions, feature exists
In the described method comprises the following steps:
(1) molten iron pre-processes；
(2) top and bottom combined blown converter smelting: when converter molten steel carbon content, phosphorus content, tapping temperature are up to standard, tapping was tapped
Carbon dust pre-deoxidation is added in journey, the preliminary alloying of mid-carbon fe-mn is added, metallurgy lime and bauxite residue adjustment is added, aluminum shot end is added
Deoxidation；
(3) Argon station: determining oxygen, and Argon is stood firm after oxygen using top argon-blowing gun and steel ladle bottom argon blowing strong mixing molten steel slugging, after
Aluminum steel, which is fed, by feeding wire machine adjusts molten steel Als content to target zone；Slag specimen and steel sample is taken to be analyzed before outbound；
(4) LF furnace refine: LF furnace slag making desulfurization, heating, adjustment chemical component, chemical component into limit and temperature it is up to standard after adjust
Whole steel ladle bottom argon blowing flow stirs molten steel only to promote high-melting-point Al2O3It is mingled with floating；Molten steel is stirred only and refers to control argon
Throughput carries out weak stirring purified treatment to molten steel；
(5) RH furnace refines, accurate adjustment chemical component to target zone；
(6) it after RH vacuum breaker, opens steel ladle bottom argon blowing and molten steel is stirred only, further promote high-melting-point Al2O3It is mingled with floating；
(7) slab caster is cast on molten steel.
In step (2), the additional amount of carbon dust is 30kg/ furnace, mid-carbon fe-mn additional amount is 5.5~6.5kg/t steel；Metallurgical stone
Grey additional amount is 5.5~6.5kg/t steel；The additional amount of bauxite is 0.3~0.8kg/t steel；The additional amount of aluminum shot be 1.5~
3.0kg/t steel.
It is described using top argon-blowing gun and steel ladle bottom argon blowing strong mixing molten steel slugging in step (3), mixing time is 4~
6min；Aluminum steel diameter 9.5mm feeds aluminum steel by feeding wire machine and adjusts molten steel Als content to target zone 0.040~0.060%.
Further, the flow of top blast argon gas is 40~80Nm3/h；The flow of ladle bottom blowing argon gas is 30~70Nm3/
h。
In step (4), by the taken slag sample analysis in Argon station as a result, aluminum shot is added, lime or bauxite carry out clinker at
Divide adjustment；The slag making of LF furnace is added at one time with aluminum shot and alloying aluminum shot.
In step (4), the outbound clinker target component of LF furnace is TFe+MnO≤1.0%；CaO:40~50%；Al2O3:25
~35%, CaO/Al2O3:1.5~1.8%.
In step (4), BOTTOM ARGON BLOWING flow set is 15~18Nm3/ h, it is ensured that the bright face of molten steel is not exposed, net mixing time >=
8min。
In step (5), for molten steel into after RH, dip pipe 400~600mm of insertion depth, vacuum degree is set as 50mbar, is promoted
140~160Nm of gas flow3/ h, RH handle 20~25min of time.
In step (6), BOTTOM ARGON BLOWING flow set is 15~18Nm3/ h, it is ensured that the bright face of molten steel is not exposed, net mixing time >=
10min。
The high-strength beam steel of 420MPa includes the chemical component of following weight percent: C 0.070~
0.090%, Si≤0.05%, Mn 0.40~0.60%, P≤0.025%, S≤0.010%, Als 0.020~0.060%,
Ti 0.050~0.065%, N 0.0040~0.0060%, surplus are iron and other inevitable impurity.
The present invention provides a kind of no Calcium treatment work by the sequence of maneuvers of converter tapping, Argon station, LF furnace and RH furnace
The control method of the high-strength automotive frame steel cleanness of 420MPa is improved under the conditions of skill, the technical principle being based on is:
In converter tapping process, Al is reduced by the way that pre-deoxidation carbon dust is added2O3It is mingled with production quantity；In Argon station process, pass through
The stirring of top bottom tentatively restores ladle slag, creates conditions for the processing of LF process；In LF furnace refining process, emphasize deoxidation and
Slag making aluminium will be added at one time, this is because primarily forming coralliform Al if aluminium is added in molten steel with a batch mode2O3
Cluster, these nanoclusters are easy to float and carry out in slag, only a small amount of close nanocluster and single Al2O3Particle is trapped in molten steel,
Its size is less than 30 μm；If aluminium is added with two batches or more batches, close to Al2O3Particle has some template Al2O3Appearance, ruler
It is very little at 5~20 μm, and secondary deoxidation generate Al2O3Particle is few.Having a size of 10~20 μm, on the collision for being unfavorable for being mingled with is grown up
Floating removal；Reasonable slag composition is separately controlled in the LF refining phase, slag desulfurization is improved and absorption is mingled with ability.Ladle slag TFe and
MnO is as low as possible, the outbound requirement (TFe+MnO)≤1.0% of LF, generates secondary oxidation to reduce the casting phase to molten steel；CaO should use up
May be big, guarantee the basicity of slag, clinker is made to have higher desulfurization and absorption to be mingled with ability, but the excessively high erosion that can be increased to furnace lining
And capacity of heat transmission reduces, and is unfavorable for utilizing electric energy, CaO target zone 40~50%；Al2O3: improve slag fluidity, target
Control is 25~35%；The weak stirring purified treatment of molten steel is used before LF furnace is outbound and after the broken sky of RH.The weak stirring of molten steel purifies
Refer to and inclusion floating promoted by weak argon gas stirring, the Argon Bubble being blown into can for 10 μm or it is smaller be not easy to be discharged be mingled with
Particle provides the matrix of adherency, so that it is adhered to bubble surface and is discharged into slag, to promote Al2O3Field trash excludes, and shortening is mingled with
Floating interval of floating dock；In RH process, due to Al2O3The density of field trash is lower than molten steel density, and molten steel recycles the phase after entering vacuum tank
Between, Al2O3Rest in vacuum tank above molten steel, and molten steel is by self-acting progress ladle, molten steel after repeatedly recycling,
Al in molten steel2O3Field trash is largely trapped in vacuum tank, as molten steel slowly enters the ladle top of the slag when broken empty, with reach with
The effect of molten steel separation.
Compared with prior art, the invention has the following advantages:
(1) compared with conventionally employed Calcium treatment technique, for the present invention in the case where not using Calcium treatment process conditions, 420MPa is high-strength
Automotive frame steel cleanness is promoted, hot rolling total oxygen content average out to 11.68ppm, complete lower than Calcium treatment technique heat hot rolling
The 15.04ppm of oxygen content；
(2) compared with conventionally employed Calcium treatment technique, the present invention in the case where not using Calcium treatment process conditions, " refining → in
The oxidizable element al attenuation average out to 0.004% of packet ", Ti attenuation average out to 0.003% are lower than Calcium treatment technique heat Al
Attenuation 0.007%, Ti attenuation 0.005%；
(3) compared with conventionally employed Calcium treatment technique, the present invention is not in the case where using Calcium treatment process conditions, properties of product value
And stability is promoted.
(4) method of the invention, the high-strength beam steel hot-rolled product yield strength average out to of 420MPa are used
468.15Mpa, standard deviation 18.27, and Calcium treatment technique heat yield strength average out to 461.12Mpa, standard deviation are
22.06；Tensile strength average out to 566.71Mpa, standard deviation 15.46, and Calcium treatment technique heat yield strength average out to
560.42Mpa standard deviation 20.08；Hot rolling thickness >=3mm elongation percentage average out to 28.05%, and Calcium treatment technique heat prolongs
Stretch rate average out to 27.80%.
Detailed description of the invention
Fig. 1 under no Calcium treatment process conditions improve the high-strength automotive frame steel cleanness of 420MPa method process flow
Figure；
Fig. 2 is the method for the invention (a) and the high-strength beam steel heat of 420MPa that traditional calcium treating method (b) produces
Roll up total oxygen comparison diagram；
Fig. 3 is that the high-strength beam steel of 420MPa that the method for the invention (a) is produced with traditional calcium treating method (b) is bent
Take intensity contrast figure；
Fig. 4 is that the high-strength beam steel of 420MPa that the method for the invention (a) is produced with traditional calcium treating method (b) resists
Tensile strength comparison diagram；
Fig. 5 is that the high-strength beam steel of 420MPa that the method for the invention (a) is produced with traditional calcium treating method (b) prolongs
Stretch rate comparison diagram.
Specific embodiment
The following describes the present invention in detail with reference to examples.
Embodiment 1
A method of the high-strength automotive frame steel cleanness of 420MPa is improved under no Calcium treatment process conditions, using 300 tons
Converter smelting, the specific steps are as follows:
(1) molten steel pre-processes；
(2) top and bottom combined blown converter smelting: after converter molten steel carbon content, phosphorus content, tapping temperature are up to standard, tapping；It tapped
Be added in journey carbon dust 30kg pre-deoxidation, be added the preliminary alloying of mid-carbon fe-mn 6.0kg/t steel, be added metallurgy lime 6.0kg/t steel,
Aluminum shot 2.5kg/t steel final deoxidizing is added in the residue adjustment of bauxite 0.5kg/t steel；
(3) Argon station: determine oxygen, oxygen content 87ppm, top argon-blowing gun and steel ladle bottom argon blowing strong mixing molten steel 4min, top blast
The flow of argon gas is 42Nm3/h；The flow of ladle bottom blowing argon gas is 35Nm3/ h, it is rear to be by feeding wire machine hello aluminum steel hello diameter
168 meters of the aluminum steel of 9.5mm adjusts molten steel Als content.Slag specimen and steel sample is taken to be analyzed before outbound, clinker TFe:12%, MnO:
4%, SiO2: 12.5%, CaO:42%, Al2O3: 19%；Steel sample Als content 0.042%；
(4) LF furnace refines: molten steel opens argon bottom-blowing, slugging after entering the station.Latter batch be added aluminum shot 152Kg take off in slag oxygen and
Molten steel Als is adjusted, aluminum shot heats up after being added, and lime 650kg is added in temperature-rise period, and manganese is added after heating in bauxite 80kg
Alloy adjusts Mn content.Chemical component and temperature it is up to standard after adjustment steel ladle bottom argon blowing flow to purification of molten steel processing, argon blowing rate
It is set as 15Nm3/ h, practical is 16Nm3/ h, net mixing time 8min.LF outbound clinker TFe:0.5%, MnO:0.3%, SiO2:
3.2%, CaO:45%, Al2O3: 32%；
(5) RH furnace refines: molten steel is post-processed into RH, dip pipe insertion depth 520mm, vacuum degree 60mbar, promotes gas
Body flow 150Nm3/ h, RH handle time 23min, RH treatment process accurate adjustment chemical component to target zone；
(6) after RH vacuum breaker, adjustment steel ladle bottom argon blowing flow is set as 15Nm to purification of molten steel processing, argon blowing rate3/ h,
Practical is 17Nm3/ h, net mixing time 12min；
(7) slab caster is cast on molten steel.
The chemical component and weight percent of the high-strength beam steel of the present embodiment 420MPa produced are as follows: C:
0.082%, Si:0.025%, Mn:0.46%, P:0.012%, S:0.002%, Als:0.042%, Ti:0.056%, N:
0.0.0044%, surplus is iron and other inevitable impurity.
In the case where not using Calcium treatment process conditions, the high-strength automotive frame steel continuous casting billet total oxygen content of 420MPa is the present embodiment
12ppm (uses Calcium treatment technique, continuous casting billet total oxygen content is 15ppm), and continuous casting casting smoothly, has no storage stream；
The present embodiment is not in the case where using Calcium treatment process conditions, and oxidizable element al attenuation is during refining-middle packet
0.005%, Ti attenuation are 0.003%, are lower than Calcium treatment technique Al attenuation (0.007%), Ti attenuation (0.005%).
Embodiment 2
A method of the high-strength automotive frame steel cleanness of 420MPa is improved under no Calcium treatment process conditions, using 300 tons
Converter smelting, the specific steps are as follows:
(1) molten steel pre-processes；
(2) top and bottom combined blown converter smelting: after converter molten steel carbon content, phosphorus content, tapping temperature are up to standard, tapping；It tapped
Be added in journey carbon dust 30kg pre-deoxidation, be added the preliminary alloying of mid-carbon fe-mn 6.2kg/t steel, be added metallurgy lime 6.4kg/t steel,
Aluminum shot 2.0kg/t steel final deoxidizing is added in the residue adjustment of bauxite 0.3kg/t steel；
(3) Argon station: determine oxygen, oxygen content 112ppm, top argon-blowing gun and steel ladle bottom argon blowing strong mixing molten steel 5min, top blast
The flow of argon gas is 63Nm3/h；The flow of ladle bottom blowing argon gas is 52Nm3/ h, it is rear to be by feeding wire machine hello aluminum steel hello diameter
316 meters of the aluminum steel of 9.5mm adjusts molten steel Als content.Slag specimen and steel sample is taken to be analyzed before outbound, clinker TFe:13%, MnO:
3.6%, SiO2: 13.1%, CaO:40%, Al2O3: 21%；Steel sample Als content 0.043%；
(4) LF furnace refines: molten steel opens argon bottom-blowing, slugging after entering the station.Latter batch be added aluminum shot 185Kg take off in slag oxygen and
Molten steel Als is adjusted, aluminum shot heats up after being added, and lime 780kg is added in temperature-rise period, and manganese is added after heating in bauxite 100kg
Alloy adjusts Mn content.Chemical component and temperature it is up to standard after adjustment steel ladle bottom argon blowing flow to purification of molten steel processing, argon blowing rate
It is set as 15Nm3/ h, practical is 17Nm3/ h, net mixing time 9min.LF outbound clinker TFe:0.4%, MnO:0.2%, SiO2:
3.8%, CaO:44%, Al2O3: 31%；
(5) RH furnace refines: molten steel is post-processed into RH, dip pipe insertion depth 540mm, vacuum degree 45mbar, promotes gas
Body flow 150Nm3/ h, RH handle time 25min, RH treatment process accurate adjustment chemical component to target zone；
(6) after RH vacuum breaker, adjustment steel ladle bottom argon blowing flow is set as 15Nm to purification of molten steel processing, argon blowing rate3/ h,
Practical is 16Nm3/ h, net mixing time 13min；
(7) slab caster is cast on molten steel.
The chemical component and weight percent of the high-strength beam steel of the present embodiment 420MPa produced are as follows: C:
0.084%, Si:0.027%, Mn:0.45%, P:0.010%, S:0.003%, Als:0.044%, Ti:0.053%, N:
0.0042%, surplus is iron and other inevitable impurity.
In the case where not using Calcium treatment process conditions, the high-strength automotive frame steel continuous casting billet total oxygen content of 420MPa is the present embodiment
11ppm (uses Calcium treatment technique, continuous casting billet total oxygen content is 15ppm), and continuous casting casting smoothly, has no storage stream；
The present embodiment is not in the case where using Calcium treatment process conditions, and oxidizable element al attenuation is during refining-middle packet
0.004%, Ti attenuation are 0.003%, are lower than Calcium treatment technique Al attenuation (0.007%), Ti attenuation (0.005%).
Embodiment 3
A method of the high-strength automotive frame steel cleanness of 420MPa is improved under no Calcium treatment process conditions, using 300 tons
Converter smelting, the specific steps are as follows:
(1) molten steel pre-processes；
(2) top and bottom combined blown converter smelting: after converter molten steel carbon content, phosphorus content, tapping temperature are up to standard, tapping；It tapped
Be added in journey carbon dust 30kg pre-deoxidation, be added the preliminary alloying of mid-carbon fe-mn 5.8kg/t steel, be added metallurgy lime 5.8kg/t steel,
Aluminum shot 2.4kg/t steel final deoxidizing is added in the residue adjustment of bauxite 0.3kg/t steel；
(3) Argon station: determine oxygen, oxygen content 140ppm, top argon-blowing gun and steel ladle bottom argon blowing strong mixing molten steel 6min, top blast
The flow of argon gas is 76Nm3/h；The flow of ladle bottom blowing argon gas is 68Nm3/ h, it is rear to be by feeding wire machine hello aluminum steel hello diameter
484 meters of the aluminum steel of 9.5mm adjusts molten steel Als content.Slag specimen and steel sample is taken to be analyzed before outbound, clinker TFe:11%, MnO:
3.8%, SiO2: 11.8%, CaO:38%, Al2O3: 18%；Steel sample Als content 0.044%；
(4) LF furnace refines: molten steel opens argon bottom-blowing, slugging after entering the station.Latter batch be added aluminum shot 185Kg take off in slag oxygen and
Molten steel Als is adjusted, aluminum shot heats up after being added, and lime 850kg is added in temperature-rise period, and manganese is added after heating in bauxite 110kg
Alloy adjusts Mn content.Chemical component and temperature it is up to standard after adjustment steel ladle bottom argon blowing flow to purification of molten steel processing, argon blowing rate
It is set as 15Nm3/ h, practical is 18Nm3/ h, net mixing time 9min.LF outbound clinker TFe:0.3%, MnO:0.2%, SiO2:
4.1%, CaO:45%, Al2O3: 30%；
(5) RH furnace refines: molten steel is post-processed into RH, dip pipe insertion depth 520mm, vacuum degree 55mbar, promotes gas
Body flow 145Nm3/ h, RH handle time 21min, RH treatment process accurate adjustment chemical component to target zone；
(6) after RH vacuum breaker, adjustment steel ladle bottom argon blowing flow is set as 15Nm to purification of molten steel processing, argon blowing rate3/ h,
Practical is 16Nm3/ h, net mixing time 12min；
(7) slab caster is cast on molten steel.
The chemical component and weight percent of the high-strength beam steel of the present embodiment 420MPa produced are as follows: C:
0.079%, Si:0.019%, Mn:0.44%, P:0.009%, S:0.002%, Als:0.045%, Ti:0.054%, N:
0.0040%, surplus is iron and other inevitable impurity.
In the case where not using Calcium treatment process conditions, the high-strength automotive frame steel continuous casting billet total oxygen content of 420MPa is the present embodiment
10ppm (uses Calcium treatment technique, continuous casting billet total oxygen content is 15ppm), and continuous casting casting smoothly, has no storage stream；
The present embodiment is not in the case where using Calcium treatment process conditions, and oxidizable element al attenuation is during refining-middle packet
0.003%, Ti attenuation are 0.004%, are lower than Calcium treatment technique Al attenuation (0.007%), Ti attenuation (0.005%).
High-strength beam steel is produced using method of the invention and traditional calcium treating method respectively, counts and evaluates sample
Average total oxygen content, average yield strength and standard deviation, average tensile strength and standard deviation, average elongation and standard deviation,
Respectively as shown in Fig. 2, Fig. 3, Fig. 4, Fig. 5.
It can be seen that compared with conventionally employed Calcium treatment technique from the statistical result in each figure, the present invention is not using calcium
Under treatment process condition, the high-strength automotive frame steel cleanness of 420MPa is promoted, hot rolling total oxygen content average out to 11.68ppm,
Lower than the 15.04ppm of Calcium treatment technique heat hot rolling total oxygen content；Adopt the high-strength automobile of the 420MPa being obtained by the present invention
Beam steel hot-rolled product yield strength average out to 468.15Mpa, standard deviation 18.26, and Calcium treatment technique heat yield strength
Average out to 461.12Mpa, standard deviation 22.03；Tensile strength average out to 566.71Mpa, standard deviation 15.46, and Calcium treatment
Technique heat tensile strength average out to 560.42Mpa, standard deviation 20.08；Hot rolling thickness >=3mm elongation percentage average out to
28.05%, and Calcium treatment technique heat elongation percentage average out to 27.81%, properties of product value and the more traditional Calcium treatment work of stability
Skill is promoted.
Above-mentioned reference embodiment is to the raising high-strength automotive frame steel cleanness of 420MPa under a kind of no Calcium treatment process conditions
Method carry out detailed description, be illustrative without being restrictive, several realities can be enumerated according to limited range
Example, therefore the change and modification in the case where not departing from present general inventive concept are applied, should be belonged within protection scope of the present invention.
Claims (10)
1. improving the method for the high-strength automotive frame steel cleanness of 420MPa under a kind of no Calcium treatment process conditions, which is characterized in that
It the described method comprises the following steps:
(1) molten iron pre-processes；
(2) it top and bottom combined blown converter smelting: when converter molten steel carbon content, phosphorus content, tapping temperature are up to standard, taps, in tapping process
Addition carbon dust pre-deoxidation, the preliminary alloying of addition mid-carbon fe-mn, addition metallurgy lime and bauxite residue adjustment, addition aluminum shot take off eventually
Oxygen；
(3) Argon station: determining oxygen, and Argon is stood firm after oxygen using top argon-blowing gun and steel ladle bottom argon blowing strong mixing molten steel slugging, after pass through
Feeding wire machine feeds aluminum steel and adjusts molten steel Als content to target zone；Slag specimen and steel sample is taken to be analyzed before outbound；
(4) LF furnace refine: LF furnace slag making desulfurization, heating, adjustment chemical component, chemical component into limit and temperature it is up to standard after adjust steel
Packet BOTTOM ARGON BLOWING flow stirs molten steel only；
(5) RH furnace refines, accurate adjustment chemical component to target zone；
(6) it after RH vacuum breaker, opens steel ladle bottom argon blowing and molten steel is stirred only；
(7) slab caster is cast on molten steel.
2. the method according to claim 1, wherein the additional amount of carbon dust is 30kg/ furnace, middle carbon in step (2)
Manganese iron additional amount is 5.5~6.5kg/t steel；Metallurgy lime additional amount is 5.5~6.5kg/t steel；The additional amount of bauxite is 0.3
~0.8kg/t steel；The additional amount of aluminum shot is 1.5~3.0kg/t steel.
3. described to use top argon-blowing gun and ladle bottom blowing the method according to claim 1, wherein in step (3)
Argon strong mixing molten steel slugging, mixing time are 4~6min；Aluminum steel diameter 9.5mm feeds aluminum steel by feeding wire machine and adjusts molten steel Als
Content is to target zone 0.040~0.060%.
4. method according to claim 1 or 3, which is characterized in that in step (3), the flow of top blast argon gas is 40~
80Nm3/h；The flow of ladle bottom blowing argon gas is 30~70Nm3/h。
5. the method according to claim 1, wherein passing through the taken slag sample analysis knot in Argon station in step (4)
Fruit is added aluminum shot, lime or bauxite and carries out slag composition adjustment；LF furnace slag making aluminum shot disposably adds with alloying aluminum shot
Enter.
6. method according to claim 1 or 5, which is characterized in that in step (4), the outbound clinker target component of LF furnace is
TFe+MnO≤1.0%；CaO:40~50%；Al2O3: 25~35%, CaO/Al2O3: 1.5~1.8%.
7. method according to claim 1 or 5, which is characterized in that in step (4), BOTTOM ARGON BLOWING flow set be 15~
18Nm3/ h, it is ensured that the bright face of molten steel is not exposed, net mixing time >=8min.
8. the method according to claim 1, wherein in step (5), molten steel is into after RH, dip pipe insertion depth
400~600mm, vacuum degree are set as 50mbar, 140~160Nm of lift gas flow3/ h, RH handle 20~25min of time.
9. the method according to claim 1, wherein BOTTOM ARGON BLOWING flow set is 15~18Nm in step (6)3/
H, it is ensured that the bright face of molten steel is not exposed, net mixing time >=10min.
10. the method according to claim 1, wherein the high-strength beam steel of the 420MPa includes following weight
The chemical component of amount percentage: C 0.070~0.090%, Si≤0.05%, Mn 0.40~0.60%, P≤0.025%, S≤
0.010%, Als 0.020~0.060%, Ti 0.050~0.065%, N 0.0040~0.0060%, surplus be iron and its
His inevitable impurity.
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