CN100467654C - Carbon steel double-roller thin-belt continuous metal cast process - Google Patents
Carbon steel double-roller thin-belt continuous metal cast process Download PDFInfo
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- CN100467654C CN100467654C CNB2006100282643A CN200610028264A CN100467654C CN 100467654 C CN100467654 C CN 100467654C CN B2006100282643 A CNB2006100282643 A CN B2006100282643A CN 200610028264 A CN200610028264 A CN 200610028264A CN 100467654 C CN100467654 C CN 100467654C
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Abstract
The invention discloses a carbon steel double-roller bond continuous metal cast process, which comprises the following steps: a, smelting and adding the titanium in the carbon steel in the smelting process; b, proceeding with the bond continuous metal cast, making the steel smelt entering the air-tight fused bath which is formed by the crystallization roller by ladle, bakie, immersion inlet, forming the casting band by cooling with the crystallization roller and rolling slightly, forming the deposit film(the component is the mixture of SiO2, manganese oxide, and titanium oxide), and leading in the mixture of inactive gas and reducing gas; c, rolling hotly, controlling the cooling and batching. The invention improves the heat diffusion between the casting band and the crystallization roller and the production efficiency, which has the lubricating function, reduces the frictional force between the casting band and the crystallization roller, and improves the surface quality of the casting band.
Description
Technical field
The present invention relates to the thin strap continuous casting technology field, particularly the carbon steel method for continuous casting sheet band by dual roller.
Background technology
One of thin strap continuous casting principal mode is the crystallization roller of molten steel through high speed rotating, and is frozen into the 2-5mm Cast Strip under the effect of rolling load.The basic craft course of thin strap continuous casting production at present is: strip caster (two rollers, single roller, tyre type)-confined chamber-kink-pinch roll-hot rolling (single chassis or two frames or nothing)-control is cold-and batches.In molten steel enters rotation through long nozzle, tundish and submerged nozzle from ladle water-cooled crystallization roller and the molten bath of side seal board formation, cooling through water-cooled crystallization roller forms the Cast Strip, by swing guide, pinch roll the Cast Strip rollgang is delivered in the Cast Strip, through hot rolls, the spray cooling, flying shear is until reeling machine.Since strip continuous casting technology have save cost, dwindle plant area, advantage such as cut down the consumption of energy, enhance productivity, this technology is just becoming the focus of each national investigator's research now, also b referred to as the revolutionary technology of metallurgy industry simultaneously.
In thin strap continuous casting technology, the heat transfer between Cast Strip and the water-cooled crystallization roller and solidify the quality that directly affects the Cast Strip and the performance of the finished product.The ways and means of the interface heat transfer between crystallization control roller and the molten steel mainly contains following several: 1) utilize the crystal roller surface texture processing to come the heat transfer of crystallization control roller.2) the sedimentary naturally oxide film that utilizes crystal roller surface to form is controlled heat transfer; 3) assign to control heat transfer by the one-tenth that changes crystal roller surface coating.4) one-tenth of pilot-gas is assigned to control and is conducted heat, and for example adds nitrogen and improves heat transfer, reduces the generation of crackle etc.
A kind of method of thin strap continuous casting is disclosed as Chinese patent application CN1183064A and U.S. Patent application US6073679.The principal character of this patent be sulphur content in the molten steel greater than 0.02%, element sulphur is to add by iron sulphide, and molten steel is silicomanganese killed steel, its manganese content is not less than 0.2%, silicon content is not less than 0.1%, aluminum content is less than 0.01%.
U.S. Patent application US5720336 has announced a kind of method of utilizing the nature deposited film to improve surface quality.This invention main technique is by the silicomanganese composition in the control steel, makes molten steel form a kind of iron that contains when crystal roller surface solidifies, manganese, the natural deposited film of the oxide compound of silicon, MnO:SiO in this deposited film
2=75%:25%, and the thickness of deposited film is less than 1 μ m.
All announced the control method of deposited film among U.S. Patent application US6059014, US5934359, US6059014 and European patent application EP 0800881, the Japanese patent application JP10029047, in order to control the composition of deposited film, between 0.2～0.3, realize by the Ca/Al ratio in the control molten steel.
Though each tool advantage of above technology also all has problems; For example change crystal roller surface coating and utilize method such as crystal roller surface texture processing all to need crystal roller surface is carried out special processing, and the coating of special composition easily peels off under the tired and stressed condition at the elevated temperature heat alternation and weares and teares the cost of equipment maintenance height; The natural deposited oxide film that forms by crystal roller surface and the gaseous constituent in airtight molten bath control that to conduct heat be a simple effective method.But in the existing disclosed technology, the composition of the natural deposited film of formation all is manganese oxide and silicon-dioxide at present.This method is limited to the effect that improves heat flow density, because the fusing point of manganese oxide and silicon-dioxide mixed oxide can not be very low, and also will approach at the thickness of the oxide film of the formation of crystal roller surface, and this requirement to the crystal roller surface cleaning improves.
Summary of the invention
The object of the present invention is to provide the superloy method for continuous casting sheet band by dual roller,
For achieving the above object, technical scheme of the present invention is,
The superloy double-roller bond continuous metal cast process, it comprises the steps:
A) smelt, in the smelting process in carbon steel the form with titanium alloy add titanium, its molten steel composition mass percent is: C:0.01-0.5, Si:0.03～0.6, Mn:0.2～1.2, P＜0.02, S＜0.02, Ti:0.02-0.1, Yu Tie;
B) thin strap continuous casting, titaniferous molten steel enters in the airtight molten bath that the crystallization roller by high speed rotating forms through submerged nozzle or current distribution device through ladle, tundish, passes through the cooling and the slight rolling formation Cast Strip of crystallization roller; Molten steel is poured into the crystal roller surface of high speed rotating in confined chamber, can form black nature deposited film on the surface of crystallization roller, and the composition of this nature deposited film is a silicon-dioxide, the mixed oxide of manganese oxide and titanium oxide; In the molten bath, introduce mixed gas, this mixed gas is the gas mixture of rare gas element and reducing gas, the ratio of reducing gas is 1%～10%; Oxygen partial pressure in the airtight molten bath is: 10
-2～10
-22
C) again through hot rolling, controlled chilling until batching.
Further, described rare gas element is argon gas or helium; Reducing gas is hydrogen or carbon monoxide.
Again, in the strip casting process of the present invention, the molar percentage of each oxide compound is in the natural deposited film: SiO
2: MnO: TiO
2=35～40%: 50～55%: 4～10%.
The thickness of crystal roller surface nature deposited film is less than 6 μ m's.
In molten steel smelting and deoxidation process, certainly exist the deoxidation products of manganese oxide and silicon oxide in the molten steel.The oxide compound of this class deoxidation products is very easily built up, and forms stable low melting point manganese oxide and silica composite oxide.This oxide compound especially under the condition of the such rapid solidification of thin strap continuous casting, very easily forms the very thin black deposited film of one deck at crystal roller surface in the process of cast.Because this deposited film fusing point reduces greatly than the fusing point of molten steel, therefore between molten steel and crystallization roller, formed liquid lubricant film, played effectively and lubricated, improve heat transfer and wait effect.Fig. 1 is the phasor of manganese oxide and silicon-dioxide.According to phasor as can be seen, for manganese oxide and silica composite oxide, best ratio is to be approximately SiO
2: MnO=40%:60%, this moment, the fusing point of oxide compound was 1251 ℃.
After the fusing point of natural deposited oxide film reduces, then oxide film increased in the high-temperature liquid state residence time, and then oxide film has played the effect of lubricated crystal roller surface, has reduced the frictional force of Cast Strip and crystal roller surface, improve heat transfer, and improved the surface quality of Cast Strip.If think further to reduce fusing point, improve effect, only be that manganese oxide and silica composite oxide are not reach.Therefore must by the control rational proportion, reduce fusing point by changing the composition of composite oxides.
Titanium in molten steel very easily with molten steel in nitrogen react:
Ti+[N]＝TiN
The TiN that the reaction back forms is tiny being mingled with, and is pinned at the effect that crystal boundary plays crystal grain thinning in process of setting.TiN can not precipitate into crystal roller surface in process of setting, form the film of TiN at crystal roller surface.Therefore the oxygen level that must control in the airtight molten bath is carried out following reaction: Ti+[O]=TiO
2. titanium oxide easily with molten steel in manganese oxide, silicon-dioxide formation complex inclusion is deposited on the surface of crystallization roller.It is 5% o'clock phasor that Fig. 2 has provided the titanium oxide ratio, according to phasor we as can be seen, when the titanium oxide that contains 5% in the composite oxides of manganese oxide and silicon-dioxide, the minimum fusing point of composite oxides can be reduced to 1150 ℃, effect is obvious.
Therefore purpose of the present invention is by adding suitable titanium content at steel grade, and by controlling the composition of gas in the airtight molten bath, ratio, the time of flow and gas circulation is controlled the interior oxygen partial pressure in airtight molten bath, make molten steel surface at the crystallization roller in casting process form the natural deposited film that contains a certain proportion of manganese oxide, silicon oxide and titanium oxide, by control to oxide ratios, reach control and conduct heat, improve the purpose of casting strip quality.
How much for example determining of gas flow according to the size in molten bath, it is just short that flow reaches the time of target oxygen dividing potential drop greatly, but the molten bath will be cold, and molten steel surface solidifies crust easily.The flow size is determined according to production practice.Here flow and cycling time all are in order to control oxygen partial pressure.Oxygen partial pressure has reached target call and has got final product.
In addition, it should be noted that not to be that the oxidate film is The more the better at crystal roller surface, when deposited film constantly was deposited on crystal roller surface, along with the increase of thickness of deposited film, heat flow density increased.After oxide thickness was increased to a certain degree, oxide film itself became the thermal resistance that hinders the heat transfer of crystallization roller, has reduced heat transfer.
The present invention compares with prior art:
With Chinese patent application CN1183064A and U.S. Patent application US6073679 disclose a kind of method of thin strap continuous casting different be that the principal character of this patent is to have added titanium elements in molten steel; Sulphur is not required.
With U.S. Patent application patent US5720336 announced a kind of method of utilizing the nature deposited film to improve surface quality different be that the composition of the deposited film that the present invention forms is to contain titanium, silicon, manganese, the oxide film of iron.Wherein in the deposited film of oxide compound, the ratio of titanium oxide is greater than 4%.Titaniferous oxidate film is lower than the fusing point of no titanyl compound deposited film, so lubricant effect is better.And the thickness of natural deposited film also can thicken, and reduced the cleaning of crystal roller surface.
What the control method of the deposited film that the present invention and U.S. Patent application patent US6059014, US5934359, US6059014 and European patent application EP 0800881, Japanese patent application JP10029047 announce was different is, the present invention is the ratio of titanium oxide in the controlled oxidation film, rather than the ratio of controlled oxidation calcium.
Major advantage of the present invention has:
After having increased titanium content in the molten steel, formed the natural deposited film of titaniferous oxide compound at crystal roller surface, the fusing point of this deposited film is than the fusing point low (80 ℃) of disclosed manganese oxide and silicon-dioxide nature deposited film, this liquid slag has filled up because Cast Strip that contraction causes and the air gap between the crystallization roller, improved greatly Cast Strip and crystal roller surface between heat transfer, improved more than 3 times than existing technology.Improve productivity greatly, reduced production cost;
The deposited film fusing point that contains suitable titanium oxide ratio is lower, and this deposited film has played lubrication, has reduced the frictional force between Cast Strip and the crystallization roller, has improved the surface quality of Cast Strip; Because fusing point is low, allow the thickness of deposited film to increase simultaneously.
Description of drawings
Fig. 1 is MnO-SiO
2Phasor;
Fig. 2 is MnO-SiO of the present invention
2-TiO
2Phasor;
Fig. 3 is the relation of the thickness and the mean heat flux of crystal roller surface deposited film;
Fig. 4 is cast synoptic diagram in Cast Strip of the present invention;
Fig. 5 is a gas drawing-in system device synoptic diagram of the present invention;
Fig. 6 is the metallographic structure synoptic diagram of sedimentary manganese oxide of crystal roller surface and silicon-dioxide mixed oxide;
Fig. 7 is the sedimentary manganese oxide of crystal roller surface, the metallographic structure synoptic diagram of silicon-dioxide and titanium oxide mixed oxide;
Fig. 8 is the titanium content in the molten steel and the relation of hot-fluid.
Embodiment
The present invention realizes as follows:
Referring to Fig. 4, in the smelting process of molten steel, add titanium alloy, the molten steel that will meet the composition requirement enters in the water-cooled crystallization roller 5 of rotation, the molten bath that side seal 7 forms through long nozzle 2, tundish 3 and submerged nozzle 4 from ladle 1, cooling through water-cooled crystallization roller 5 forms Cast Strip 15, by swing guide 11, pinch roll 14 hot rolling is delivered in Cast Strip 15, warp, controlled chilling are until batching again.13 is the slag car, and 6 is service platform.
Introduce a gas introducing apparatus system in the molten bath, this system comprises gas inlet tube road 8, and under meter 9a, 9b and flow control valve 10a, 10b are referring to Fig. 5.
Before the cast beginning, at first open argon gas and hydrogen valve, requirement according to technology, control rational proportion by regulating flow control valve 10a, 10b and under meter 9a, 9b, the gas that is mixed in proportion is full of confined chamber 12, and the oxygen partial pressure that oxygen partial pressure tester 17 detects in the airtight molten bath is installed on gas outlet pipe road 16.
Embodiment 1:
Add titanium 0.04%Ti at common carbon steel composition, opinion is in argon gas or argon gas hydrogen gas mixture, and the sedimental composition of crystal roller surface is a silicon oxide, the mixed oxide of manganese oxide and titanium oxide, and the pattern of oxide compound is seen Fig. 4.When gas was argon gas, this moment, oxygen partial pressure was 10
-2～10
-4In the scope, this moment, mean heat flux was 8MW/m
2, when gas is Ar-10%H
2The time, oxygen partial pressure can reach 10
-22Atm, mean heat flux reaches 12MW/m
2
Embodiment 2:
Add titanium 0.1%Ti at common carbon steel composition, opinion is in argon gas or argon gas hydrogen gas mixture, and the sedimental composition of crystal roller surface is a silicon oxide, the mixed oxide of manganese oxide and titanium oxide, and when gas was argon gas, this moment, oxygen partial pressure was 10
-2～10
-4In the scope, this moment, mean heat flux was 10MW/m
2, when gas is Ar-5%H
2The time, oxygen partial pressure can reach 10
-14Atm, mean heat flux reaches 14MW/m
2
Heat flow density improves, and for the identical processing parameter of same steel grade, the coefficient of heat transfer improves, and the coefficient of heat transfer improves, and pulling rate just can improve, and has therefore improved productivity.
Comparative Examples:
Do not have titanium in common carbon steel composition, or add titanium content less than 0.02%Ti, no matter in argon gas or argon gas hydrogen gas mixture, the sedimental composition of crystal roller surface is the oxide compound of silicon oxide and manganese oxide, and its pattern is seen shown in Figure 3.Crystal roller surface does not have the deposited film that contains titanium oxide, and average heat flow density is 4MW/m
2
Pouring molten steel is finished in confined chamber.Before cast, in confined chamber, feed the mixed gas of argon gas or argon gas and hydrogen.Fig. 8 adds the influence of different titanium contents to mean heat flux in the molten steel.When the titaniferous amount was above greater than 0.04%, no matter be at argon gas or at the mixed atmosphere environment of argon gas and hydrogen, the heat transfer between crystallization roller and the molten steel strengthens greatly, heat flow density was brought up to 16MW/m2 by average 4MW/m2.Heat flow density has improved 4 times.Heat flow density improves, and for the identical processing parameter of same steel grade, the coefficient of heat transfer improves, and the coefficient of heat transfer improves, and pulling rate just can improve, and has therefore improved productivity.
Molten steel can form a kind of sedimentary naturally oxide film at crystal roller surface in process of setting, when molten steel is common carbon steel, there is not titanium, perhaps titanium content was less than 0.04% o'clock, the sedimental composition of crystal roller surface is the oxide compound of silicon oxide and manganese oxide, and its pattern is seen shown in Figure 6.When titanium content in the molten steel is increased to more than 0.04%, the sedimental composition of crystal roller surface is a silicon oxide, the mixed oxide of manganese oxide and titanium oxide, and the pattern of oxide compound is seen Fig. 7.
Fig. 1 is the phasor when deposited film does not have titanium oxide, when the composition of deposited film is the oxide compound of silicon oxide and manganese oxide, and SiO
2: MnO=36%:64%, this moment, the fusing point of oxide compound was 1306 ℃;
Fig. 2 is the phasor that contains in the deposited film behind the titanium oxide.The silicon oxide that forms, manganese oxide, the fusing point of titanium oxide composite oxides are 1212 ℃.After the fusing point of natural deposited oxide film reduces, then oxide film increased in the high-temperature liquid state residence time, and then oxide film has played the effect of lubricated crystal roller surface, has reduced the frictional force of Cast Strip and crystal roller surface, improve heat transfer, and improved the surface quality of Cast Strip.
Fig. 3 has provided the relation of the thickness and the hot-fluid of deposited film of the present invention, and therefrom the thickness of deposited film can reach 6 μ m as can be seen, increases greatly than disclosed document 1 μ m.So just reduce the cleaning of crystal roller surface, reduced running cost.
But, be not that the oxidate film is The more the better at crystal roller surface, when deposited film constantly was deposited on crystal roller surface, along with the increase of thickness of deposited film, heat flow density increased.After thickness was increased to more than the 6 μ m, the thickness heat flow density that has increased oxide film reduced, and sees Fig. 3.This is because after oxide thickness was increased to a certain degree, oxide film itself became the thermal resistance that hinders the heat transfer of crystallization roller, has reduced heat transfer.
In sum, the present invention is by having increased titanium content in molten steel, formed the natural deposited film of titaniferous oxide compound at crystal roller surface, this liquid slag has filled up because Cast Strip that contraction causes and the air gap between the crystallization roller, improved greatly Cast Strip and crystal roller surface between heat transfer, improve productivity greatly, reduced production cost; Simultaneously, the deposited film that contains suitable titanium oxide ratio also has lubrication, has reduced the frictional force between Cast Strip and the crystallization roller, has improved the surface quality of Cast Strip; Because fusing point is low, allow the thickness of deposited film to increase simultaneously.
Claims (4)
1. superloy double-roller bond continuous metal cast process, it comprises the steps:
A) smelt, in the smelting process in carbon steel the form with titanium alloy add titanium, its molten steel composition mass percent is: C:0.01～0.5, Si:0.03～0.6, Mn:0.2～1.2, P＜0.02, S＜0.02, Ti:0.02～0.1, Yu Tie;
B) thin strap continuous casting, titaniferous molten steel enters in the airtight molten bath that the crystallization roller by high speed rotating forms through submerged nozzle or current distribution device through ladle, tundish, passes through the cooling and the slight rolling formation Cast Strip of crystallization roller; Molten steel is poured into the crystal roller surface of high speed rotating in confined chamber, can form black nature deposited film on the surface of crystallization roller, and the composition of this nature deposited film is a silicon-dioxide, the mixed oxide of manganese oxide and titanium oxide; In the molten bath, introduce mixed gas, this mixed gas is the gas mixture of rare gas element and reducing gas, the ratio of reducing gas is 1%～10%; Oxygen partial pressure in the airtight molten bath is: 10
-2～10
-22Atm;
C) again through hot rolling, controlled chilling until batching.
2. carbon steel double-roller bond continuous metal cast process as claimed in claim 1 is characterized in that, described rare gas element is argon gas or helium; Reducing gas is hydrogen or carbon monoxide.
3. carbon steel double-roller bond continuous metal cast process as claimed in claim 1 is characterized in that the molar percentage of each oxide compound is in the natural deposited film: SiO
2: MnO: TiO
2=35～40%: 50～55%: 4～10%.
4. as claim 1 or 3 described carbon steel double-roller bond continuous metal cast process, it is characterized in that the thickness of crystal roller surface nature deposited film is less than 6 μ m.
Priority Applications (1)
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|---|---|---|---|
| CNB2006100282643A CN100467654C (en) | 2006-06-28 | 2006-06-28 | Carbon steel double-roller thin-belt continuous metal cast process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006100282643A CN100467654C (en) | 2006-06-28 | 2006-06-28 | Carbon steel double-roller thin-belt continuous metal cast process |
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| CN100467654C true CN100467654C (en) | 2009-03-11 |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102002628B (en) * | 2009-08-31 | 2012-07-25 | 宝山钢铁股份有限公司 | Method for manufacturing low-carbon steel sheets |
| CN101736198B (en) * | 2010-01-21 | 2011-10-12 | 山西太钢不锈钢股份有限公司 | Hot rolled band for container and method for manufacturing same |
| CN103911486B (en) * | 2014-04-03 | 2016-04-20 | 莱芜钢铁集团有限公司 | A kind of method removing titanium in bearing steel molten steel |
| CN105463309B (en) * | 2015-12-01 | 2017-07-07 | 攀钢集团西昌钢钒有限公司 | A kind of production method for eliminating low carbon mild steel cross breaks defect |
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