CN116640905A - Manufacturing method for smelting thin cold-rolled base stock under high pulling speed condition - Google Patents
Manufacturing method for smelting thin cold-rolled base stock under high pulling speed condition Download PDFInfo
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 36
- 238000003723 Smelting Methods 0.000 title claims abstract description 35
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 137
- 239000010959 steel Substances 0.000 claims abstract description 137
- 238000000034 method Methods 0.000 claims abstract description 89
- 230000008569 process Effects 0.000 claims abstract description 61
- 238000005266 casting Methods 0.000 claims abstract description 50
- 238000007670 refining Methods 0.000 claims abstract description 47
- 239000002893 slag Substances 0.000 claims abstract description 40
- 238000010079 rubber tapping Methods 0.000 claims abstract description 35
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 25
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000000463 material Substances 0.000 claims abstract description 23
- 238000005261 decarburization Methods 0.000 claims abstract description 12
- 238000005275 alloying Methods 0.000 claims abstract description 7
- 230000000903 blocking effect Effects 0.000 claims abstract description 4
- 239000011575 calcium Substances 0.000 claims description 52
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 43
- 229910052791 calcium Inorganic materials 0.000 claims description 43
- 238000007664 blowing Methods 0.000 claims description 33
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- 229910052786 argon Inorganic materials 0.000 claims description 11
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 11
- 229910052760 oxygen Inorganic materials 0.000 claims description 11
- 239000001301 oxygen Substances 0.000 claims description 11
- 230000001502 supplementing effect Effects 0.000 claims description 11
- 239000007788 liquid Substances 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 9
- 238000001816 cooling Methods 0.000 claims description 8
- 238000007872 degassing Methods 0.000 claims description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 6
- 208000029154 Narrow face Diseases 0.000 claims description 6
- 239000010949 copper Substances 0.000 claims description 6
- 229910052802 copper Inorganic materials 0.000 claims description 6
- 238000007599 discharging Methods 0.000 claims description 6
- 230000005674 electromagnetic induction Effects 0.000 claims description 6
- 238000009489 vacuum treatment Methods 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 239000003795 chemical substances by application Substances 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 229910001208 Crucible steel Inorganic materials 0.000 claims 1
- 238000005096 rolling process Methods 0.000 abstract description 12
- 239000000047 product Substances 0.000 description 14
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 11
- 229910052757 nitrogen Inorganic materials 0.000 description 8
- 238000009749 continuous casting Methods 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 230000001276 controlling effect Effects 0.000 description 5
- 230000007547 defect Effects 0.000 description 5
- 229910052698 phosphorus Inorganic materials 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- 229910052717 sulfur Inorganic materials 0.000 description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
- 230000003749 cleanliness Effects 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 238000005336 cracking Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000004886 process control Methods 0.000 description 3
- 239000013589 supplement Substances 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000004134 energy conservation Methods 0.000 description 2
- 238000005189 flocculation Methods 0.000 description 2
- 230000016615 flocculation Effects 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- CSJDCSCTVDEHRN-UHFFFAOYSA-N methane;molecular oxygen Chemical compound C.O=O CSJDCSCTVDEHRN-UHFFFAOYSA-N 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000012496 blank sample Substances 0.000 description 1
- XFWJKVMFIVXPKK-UHFFFAOYSA-N calcium;oxido(oxo)alumane Chemical compound [Ca+2].[O-][Al]=O.[O-][Al]=O XFWJKVMFIVXPKK-UHFFFAOYSA-N 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010835 comparative analysis Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/20—Controlling or regulating processes or operations for removing cast stock
-
- 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
- C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention discloses a manufacturing method of a smelting thin cold-rolled base material under a high pulling speed condition. The manufacturing method comprises the following steps: 1) Pre-desulfurizing molten steel; 2) Smelting molten steel by a decarburization converter; 3) Tapping steel to the steel ladle, wherein the tapping process is matched with a tapping slag blocking process, and deoxidation alloying is not performed; 4) Refining molten steel by adopting an RH furnace until the content of acid-soluble aluminum Als is 0.03-0.05 wt%; 5) Refining molten steel by adopting an LF furnace; 6) Protecting casting into blank with pulling speed not less than 4.5m/min. The method can solve the problems that the control difficulty of inclusions is high, and holes appear in finished products or the finished products are broken in the drawing process due to exposure of large-scale inclusions when smelting the thin-specification high-rolling cold-rolled base material, and the high-rolling cold-rolled base material produced under the high-drawing speed condition can meet the production technical requirements of thin-specification strip steel and the requirements of maximization of profit of customers.
Description
Technical Field
The invention relates to the technical field of steel manufacturing, in particular to a manufacturing method for smelting a thin cold-rolled base material under the condition of high pulling speed.
Background
In modern steelmaking production, the continuous casting high-pulling speed condition is the basis for realizing continuous casting and rolling, can realize production intensification, resource and energy circulation, energy consumption minimization and economic benefit optimization, is the internal requirement of energy conservation and emission reduction of iron and steel enterprises in China, and has important significance for all iron and steel enterprises due to technical progress and product structure adjustment.
However, under the high-pulling-speed process condition, such as a typical CSP continuous casting and rolling short flow, the pulling speed of normal production is higher than 4.5m/min, the defect improvement rate of the surface impurity inclusion defect of the produced high-rolling cold-rolled base material is higher than 1.2%, the component qualification rate is lower than 95%, the casting steel casting rate is higher than 0.8%, and the product quality is poor. In addition, the final rolling thickness of the finished product of the high-rolling cold-rolled base material is only about 0.1mm, so that the surface quality requirement is higher, and the control difficulty of inclusions is higher. Exposure of large inclusions (inclusions > 100 μm in size) will cause the finished product to void or fracture during drawing, affecting normal use by the customer.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a manufacturing method for smelting a thin cold-rolled base material under the high-drawing-speed condition, so as to solve the problems of large inclusion control difficulty, low production efficiency, high cost and the like in the thin high-rolling cold-rolled base material under the high-drawing-speed process condition, and achieve the aims of energy conservation, environmental protection and cost reduction.
In order to achieve the aim, the invention discloses a manufacturing method for smelting a thin cold-rolled base material under the condition of high pulling speed, which comprises the following steps:
1) Pre-desulfurizing molten steel;
2) Smelting molten steel by a decarburization converter;
3) Tapping steel to the steel ladle, wherein the tapping process is matched with a tapping slag blocking process, and deoxidation alloying is not performed;
4) Refining molten steel by adopting an RH furnace until the content of acid-soluble aluminum Als is 0.03-0.05 wt%;
5) Refining molten steel by adopting an LF furnace;
6) Protecting casting into blank with pulling speed not less than 4.5m/min.
Preferably, the S content of the molten steel obtained in the step 1) is 0.001 to 0.005wt%; the C content of the molten steel in the step 2) is 0.04-0.07 wt% and the total oxygen content T [ O ] is 450-750 ppm; the C content of the molten steel obtained in the step 4) is less than or equal to 0.01 percent, and the step 4) adopts an aluminum-free deoxidizer to reduce the total oxygen content T [ O ] to 50ppm-350ppm after RH refining.
Preferably, the molten steel obtained in the step 5) comprises the following chemical components in percentage by mass: 0.01 to 0.04 percent, si:0 to 0.04 percent, mn:0.10 to 0.3 percent, P:0 to 0.020 percent, S:0 to 0.005 percent, al: 0.02-0.04%, ca:0.0010 to 0.0035 percent, N:0 to 0.0050 percent, and the balance being Fe.
Preferably, the tapping temperature in the step 3) is 1400-1650 ℃, and the tapping time is 4-9 min.
Preferably, the highest vacuum degree of the RH refining process in the step 4) is less than or equal to 3mbar, the vacuum treatment time is 8-20 min, the pure degassing time is more than or equal to 6min, and the dosage of the aluminum-free deoxidizer is 0.3-0.5 kg/t.
Preferably, the LF refining of step 5) includes a soft blowing and calcium treatment process: the wire feeding amount of the calcium treatment is 400+/-30 m/furnace, the soft blowing before the calcium treatment is carried out for 8-12 min, the soft blowing flow before the calcium treatment is 200-800 NL/min, the soft blowing after the calcium treatment is more than or equal to 12min, the soft blowing flow before the soft blowing after the calcium treatment is 200-600 NL/min, and the soft blowing flow after the calcium treatment is 80-220 NL/min, so that the Ca content of the obtained molten steel is more than or equal to 20ppm or Ca/Als is more than or equal to 0.08.
Preferably, the LF refining time in the step 5) is 40-80 min; al is supplemented in the LF refining process to ensure that the Al content reaches 0.02-0.04 percent, and aluminum supplementing operation is not carried out in 8min before calcium treatment; the whole process of LF refining is controlled by micro positive pressure, the wire feeding process is protected by argon, and the process increment [ N ] < 10ppm.
Preferably, the number of times of the reblowing is not more than one in the smelting of the converter (oxygen content remains after the RH decarburization due to the carbon-oxygen imbalance of the molten steel after the reblowing, and slag oxidizing property is strong, and a large amount of aluminum inclusions are generated in the process of removing the residual oxygen from the slag and the molten steel).
Preferably, in the step 6), the tundish is cast: the ladle molten steel is not drained, the [ N ] is increased to be less than or equal to 3ppm in the casting process, the normal full ladle casting tonnage of the tundish is more than 45t, and the steel passing amount of the tundish is less than or equal to 5.0t/min.
Preferably, in the step 6), the tonnage of the ladle in the casting steel is not lower than 2/3 of the full ladle at the lowest; the low-carbon low-silicon high-alkalinity tundish covering agent is used, the slag alkalinity of an impact zone is more than 1.5, and FeO+MnO is less than 3%; the normal tonnage of the tundish is more than 45t.
Preferably, the big ladle adopts a low-position casting method; and (3) controlling the superheat degree of the middle ladle: 20-30 ℃; the water quantity of the crystallizer is automatically set according to the thickness of the wide-face narrow-face copper plate, the secondary cooling parameters are set according to the casting section, and forced cooling is adopted, so that the specific water quantity is more than or equal to 2.9l/kg; pulling speed: when the thickness of the casting blank is 70-90mm, the target pulling speed is 5.2+/-0.2 m/min; when the thickness of the casting blank is 90-110mm, the target pulling speed is 5.0 m+/-0.2/min; electromagnetic braking is adopted, the current intensity is 145+/-15A, and the standard deviation of fluctuation of the liquid level of the crystallizer is less than or equal to 2.5mm; and a ladle electromagnetic induction slag discharging system is adopted, and a sliding plate with the proportion of steel slag reaching 12-30% is automatically closed.
Compared with the prior art, the invention has the advantages and positive effects that: the manufacturing method of the smelting thin cold-rolled base material under the high-drawing speed condition meets the control requirements of high production efficiency, the quantity and the size of inclusions, the quantity and the size of nonmetallic inclusions in the inclusions can be controlled, the large inclusions float upwards fully, the large inclusions are prevented from being involved in the continuous casting process, the size and the quantity of the large inclusions are controlled within a certain range, and the product quality is stabilized. The high-rolling cold-rolled base material produced by the method under the high-pulling speed condition can meet the production technical requirements of thin-specification strip steel and the requirements of clients on profit maximization.
Detailed Description
The present invention will be specifically described below by way of exemplary embodiments. It is to be understood that structures and features in one embodiment may be beneficially incorporated in other embodiments without further recitation.
A manufacturing method for smelting a thin cold-rolled base material under the high-pulling-speed condition comprises the following steps:
1) Pre-desulfurizing molten steel;
2) Smelting molten steel by a decarburization converter;
3) Tapping steel to the steel ladle, wherein the tapping process is matched with a tapping slag blocking process, and deoxidation alloying is not performed;
4) Refining molten steel by adopting an RH furnace until the content of acid-soluble aluminum Als is 0.03-0.05 wt%;
5) Refining molten steel by adopting an LF furnace;
6) Protecting casting into blank with pulling speed not less than 4.5m/min.
The defects of the existing high-pulling-speed process products are mainly caused by that inclusions are not easy to float up and the liquid level of a crystallizer fluctuates and are involved in the casting powder in the steelmaking process of deoxidation, refining and slagging, continuous casting and secondary oxidation. The manufacturing method of the embodiment can prepare thinner casting blanks (70-110 mm) by optimizing the manufacturing process at a high pulling speed (the pulling speed is more than or equal to 4.5 m/min), and the method can solve the problems that the control difficulty of inclusions is high, holes are formed in finished products or the finished products are broken in the pulling process due to exposure of large-sized inclusions when smelting thin high-rolling cold-rolled base materials, and the high-rolling cold-rolled base materials produced under the high pulling speed condition can meet the production technical requirements of thin-specification strip steel and the requirements of maximization of profit of customers. The conventional Als of the RH outlet is less than or equal to 0.03 weight percent, the method of the embodiment improves the content of the RH outlet aluminum, and controls the Als to be 0.03 to 0.05 weight percent, and has the following technical effects: since RH only decarbonizes and deoxidizes molten steel and the oxidizing property of slag is still strong, if the slag is not deoxidized, oxygen in the slag diffuses into the molten steel in the casting process, and the cleanliness of the molten steel is poor, so that the slag needs to be deoxidized by stirring at LF. Als in molten steel can be oxidized during LF deoxidation, for example, the Als of the molten steel is low due to low RH outlet Als and LF stirring oxidization, aluminum supplementing is needed, the molten steel needs stirring after aluminum supplementing to ensure uniform components, and accordingly LF total stirring time is increased, and the total amount of inclusions is increased. If the RH outlet aluminum is too high, als loss is increased in the LF stirring process, the produced inclusion is high, and the control of molten steel cleanliness is not facilitated. Meanwhile, the steel slag sample is unbalanced due to the fact that Als is too high, the diffusion of oxygen in slag into molten steel and the diffusion of oxygen in air into slag are aggravated, and molten steel inclusions are increased. So that the excessive high and low RH outlet aluminum directly affects the quality of molten steel, and the RH outlet Als is controlled to be 0.03-0.05 wt%.
Wherein, in order to more effectively control the quantity and the size of nonmetallic inclusion in the inclusion, the method optimally controls the content of chemical components in each process step, and the S content of the molten steel obtained in the step 1) is 0.001-0.005 wt%; the C content of the molten steel in the step 2) is 0.04-0.07 wt% and the total oxygen content T [ O ] is 450-750 ppm; the C content of the molten steel obtained in the step 4) is less than or equal to 0.01 percent; step 4) adopting aluminum-free deoxidizer to reduce the total oxygen content T [ O ] to 50-350 ppm after RH refining; the molten steel obtained in the step 5) comprises the following chemical components in percentage by mass: 0.01 to 0.04 percent, si:0 to 0.04 percent, mn:0.10 to 0.3 percent, P:0 to 0.020 percent, S:0 to 0.005 percent, al: 0.02-0.04%, ca:0.0010 to 0.0035 percent, N:0 to 0.0050 percent, and the balance being Fe.
Wherein the tapping temperature of the step 3) is 1400-1650 ℃ and the tapping time is 4-9 min.
Wherein, the highest vacuum degree in the RH refining process in the step 4) is less than or equal to 3mbar, the vacuum treatment time is 8-20 min, the pure degassing time is more than or equal to 6min, and the dosage of the aluminum-free deoxidizer is 0.3-0.5 kg/t. The step utilizes the carbon-oxygen reaction under good dynamic conditions under high vacuum degree to remove C to below 100ppm, and adopts aluminum-free deoxidized alloy to reduce aluminum inclusion generated by aluminum deoxidizer; in the step, the net circulation time is properly prolonged, the mixing time requirement of 3 times of molten steel circulation in the ladle is met, and the full collision, growth and floating of aluminum deoxidization products are promoted; meanwhile, the alumina product with high melting point is clustered and is easy to be captured by ladle top slag, so that molten steel is sufficiently purified. RH molten steel circulation flow rate:
wherein G is the flow rate of lifting gas, and the unit is Nl/min; ds is the inner diameter of the dip tube in m; pvac is vacuum pressure in torr; p is the ambient pressure in torr.
According to RH equipment and process parameter calculation, the pure degassing time required by 3 times of molten steel circulation is 5min, and the pure circulation time (pure degassing time) is set to be more than or equal to 6min in order to ensure that molten steel is fully mixed.
Wherein, the LF refining of the step 5) comprises the following soft blowing and calcium treatment processes: the feeding amount of the calcium treatment is 400 m/furnace, the feeding amount of molten steel is regulated to +/-30 m abnormally, the soft blowing before the calcium treatment is carried out for 8-12 min, the soft blowing flow before the calcium treatment is 200-800 NL/min, the soft blowing after the calcium treatment is more than or equal to 12min, the soft blowing flow before the soft blowing after the calcium treatment is 200-600 NL/min, and the soft blowing flow after the soft blowing is 80-220 NL/min, so that the Ca content of the obtained molten steel is more than or equal to 20ppm or Ca/Als is more than or equal to 0.08. The LF refining of this embodiment can avoid the molten steel to expose in the air and secondary oxidation forms to mix with in the argon protection of pressure-fired, wire feeding process, and accurate calcium treatment and soft blowing process can promote the come-up of deoxidization result to get rid of on the one hand, on the other hand can denature aluminium oxide into low-melting calcium aluminate, avoids enriching and growing up and forming the mouth of a river plug in continuous casting pouring process, becomes the source of defects such as hole, fracture after being washed into the crystallizer. The conventional process for producing clean steel is to denature the inclusions into 12 CaO.7Al 2 O 3 The calcium treatment in this example was carried out by denaturing inclusions into 3 CaO. Al 2 O 3 The inclusions were denatured to 12 CaO.7Al 2 O 3 CaO/Al is actually generated during casting 2 O 3 The high melting point material caused flocculation, the aggregation length of the inclusions was large, and the cleanliness of the molten steel was poor, and the inclusions were denatured into 3 CaO. Al in this example 2 O 3 The type of inclusion derived during casting was 3CaO.Al 2 O 3 And 12 CaO.7Al 2 O 3 The impurities with low melting point do not have flocculation flow, and the impurities do not aggregate and grow up, so that the cleanliness of molten steel is improved. The soft blowing before and after the calcium treatment in the conventional calcium treatment process are both 8-10min, and the flow is the same. In order to achieve the above effect, the soft blowing flow rate before the calcium treatment is properly increased, and meanwhile, the soft blowing time before the calcium treatment is properly shortened, before the calcium line is not added, the inclusions are not deformed, clustered inclusions, the inclusions need a larger flow rate and are easily captured by argon bubbles to be finally removed, the morphology of the inclusions is changed after the calcium treatment, the surfaces of the inclusions become smoother, at the moment, the adsorption capacity of the bubbles to the inclusions is weakened, the bubbles are required to drive molten steel to be weakly stirred, and the inclusions are brought to a steel slag interface to be adsorbed by slag.
Specifically, the LF refining time in the step 5) is 40-80 min; al is supplemented in the LF refining process to ensure that the Al content reaches 0.02-0.04 percent, and aluminum supplementing operation is not carried out in 8min before calcium treatment; the whole process of LF refining is controlled by micro positive pressure, the wire feeding process is protected by argon, and the process increment [ N ] < 10ppm.
Specifically, in the smelting of the converter, the number of times of the supplementary blowing is not more than one.
Specifically, in step 6), ladle protection casting: the ladle molten steel is not drained, the [ N ] is increased to be less than or equal to 3ppm in the casting process, the normal full ladle casting tonnage of the tundish is more than 45t, and the steel passing amount of the tundish is less than or equal to 5.0t/min. With the steel passing amount of the embodiment, the actual residence time of the molten steel can be stably controlled to be more than 6min, and large inclusions with the size of more than 80 mu m in the molten steel can be fully floated and removed in the time.
Specifically, in the step 6), the lowest ladle tonnage in the steel casting is not lower than 2/3 of the full ladle; the low-carbon low-silicon high-alkalinity tundish covering agent is used, the slag alkalinity of an impact zone is more than 1.5, and FeO+MnO is less than 3%; the normal tonnage of the tundish is more than 45t. The big ladle adopts a low-position casting method; and (3) controlling the superheat degree of the middle ladle: 20-30 ℃; the water quantity of the crystallizer is automatically set according to the thickness of the wide-face narrow-face copper plate, the secondary cooling parameters are set according to the casting section, and forced cooling is adopted, so that the specific water quantity is more than or equal to 2.9l/kg; pulling speed: when the thickness of the casting blank is 70-90mm, the target pulling speed is 5.2+/-0.2 m/min; when the thickness of the casting blank is 90-110mm, the target pulling speed is 5.0 m+/-0.2/min; electromagnetic braking is adopted, the current intensity is 145+/-15A, and the standard deviation of fluctuation of the liquid level of the crystallizer is less than or equal to 2.5mm; and a ladle electromagnetic induction slag discharging system is adopted, and a sliding plate with the proportion of steel slag reaching 12-30% is automatically closed. The electromagnetic braking can well control the slag reeling risk caused by overlarge flowing strength of molten steel in the crystallizer. Meanwhile, in the conventional process, the ladle reaches the continuous casting platform to perform casting operation, in order to enable operators to clearly ladle casting, and also in order to avoid accidents caused by pressure build-up in a water gap, a ladle arm falls to a low position after casting is performed, molten steel is left to open for 30-45s in the casting process, the embodiment adopts a ladle arm falling low-position casting method, a long water gap falls to a position of 1-5cm above the liquid surface of a tundish, a plurality of argon pipes can be assembled around the long water gap to blow argon, air is exhausted, argon protection is formed, operators can judge the casting process condition through a weighing display, and secondary oxidization of molten steel in the casting process can be greatly reduced through the method of the embodiment.
Example 1
A production method for smelting a thin cold-rolled base material under the high-pulling-speed condition comprises the following steps:
1) Pre-desulfurizing molten steel: endpoint [ S ]:0.0015%;
2) Smelting molten steel by a decarburization converter: endpoint [ C ]:559ppm, T [ O ]:452ppm;
3) Tapping steel into a ladle: the tapping temperature is 1633, the tapping time is 7min; tapping to stop slag, and no deoxidization alloying is performed in the tapping process;
4) Refining molten steel by adopting an RH furnace: vacuum treatment time is 10min, and pure degassing time is 8min; outbound [ Als ]:0.047%, outbound C:60ppm;
5) Refining molten steel by adopting an LF furnace:
a. refining time control: refining time is 75min;
b. and (3) process aluminum supplementing: and (3) strictly forbidden to supplement aluminum in 8min before calcium treatment, wherein the aluminum supplementing times are as follows: 3 times;
c. and (3) gas control: the whole process of LF refining is controlled by micro positive pressure, argon is protected in the wire feeding process, nitrogen is not increased in the process, and the process control meets the standard requirement;
d. soft blowing and calcium treatment: the soft blowing time is 9min before calcium treatment, 13min after calcium treatment, the wire feeding amount is 403m, and the outlet Ca/Als is: 0.093;
the chemical components of the obtained molten steel are as follows by mass percent: 0.015%, si:0.03%, mn:0.15%, P:0.019%, S:0.002%, al:0.025%, ca:0.0023%, N:0.0025% and the balance of Fe;
6) Protecting casting into a blank at a high pulling speed:
a. the ladle is poured by a low-position pouring method;
b. and (3) controlling the superheat degree of the ladle molten steel: degree of superheat of the tundish: 21, a liquidus temperature of 1534; DEG C
c. The ladle molten steel is not drained, and the N is increased to less than or equal to 2ppm in the pouring process;
c. the water quantity of the crystallizer is automatically set according to the thickness of the wide-face and narrow-face copper plate;
d. pulling speed: 4.9m/min, steel passing amount of tundish: 4.5t/min;
e. electromagnetic braking current: 130-150A, standard deviation of fluctuation of the liquid level of the crystallizer: 1.5mm; the wave level is controlled, so that liquid level fluctuation control can avoid molten steel from being involved in protective slag, and large particles are mixed in a steel billet after molten steel is involved in the protective slag if the liquid level fluctuation is large.
f. And the steel ladle electromagnetic induction slag discharging system is characterized in that a 15% steel slag proportion sliding plate is closed. The molten steel can generate vortex in the ladle in the later casting period, the steel slag can be rolled into a tundish, and if the slag floats up in the tundish, the slag can enter a casting blank to become large-particle inclusion, so the embodiment controls the closing time of the sliding plate.
The whole surface quality of the cold-rolled base material produced by the method of the embodiment is basically normal through statistics, and the casting blank is all [ O ]:25ppm, [ N ]:26ppm. The detection size of the inclusions is smaller than 20 mu m, the phenomena of holes, cracking and the like caused by the inclusions do not occur, and the quality of the finished product is good.
Example 2
A production method for smelting a thin cold-rolled base material under the high-pulling-speed condition comprises the following steps:
1) Pre-desulfurizing molten steel: endpoint [ S ]:0.002%;
2) Smelting molten steel by a decarburization converter: endpoint [ C ]:480ppm, T [ O ]:480ppm of;
3) Tapping steel into a ladle: tapping temperature 1640 ℃ and tapping time 7min; tapping to stop slag, and no deoxidization alloying is performed in the tapping process;
4) Refining molten steel by adopting an RH furnace: vacuum treatment time is 16min, and pure degassing time is 8min; outbound [ Als ]:443ppm, out C:52ppm;
5) Refining molten steel by adopting an LF furnace:
a. refining time control: refining time is 75min;
b. and (3) process aluminum supplementing: and (3) strictly forbidden to supplement aluminum in 8min before calcium treatment, wherein the aluminum supplementing times are as follows: 3 times;
c. and (3) gas control: the whole process of LF refining is controlled by micro positive pressure, argon is protected in the wire feeding process, nitrogen is not increased in the process, and the process control meets the standard requirement;
d. soft blowing and calcium treatment: the soft blowing time is 8min before calcium treatment, 12min after calcium treatment, the wire feeding amount is 425m, and the outlet Ca/Als:0.081;
the chemical components of the obtained molten steel are as follows by mass percent: 0.02%, si:0.02%, mn:0.11%, P:0.015%, S:0.001%, al:0.028%, ca:0.0023%, N:0.0036% and the balance of Fe;
6) Protecting casting into a blank at a high pulling speed:
a. the ladle is poured by a low-position pouring method;
b. and (3) controlling the superheat degree of the ladle molten steel: degree of superheat of the tundish: 23 ℃, liquidus temperature 1534; DEG C
c. The ladle molten steel is not drained, and the N is increased to less than or equal to 2ppm in the pouring process;
c. the water quantity of the crystallizer is automatically set according to the thickness of the wide-face and narrow-face copper plate, and forced cooling is adopted;
d. pulling speed: 4.9m/min, steel passing amount of tundish: 4.5t/min;
e. electromagnetic braking current: 130-150A, and the standard deviation control range of the fluctuation of the liquid level of the crystallizer is 0.4-1.2mm;
f. and the steel ladle electromagnetic induction slag discharging system is characterized in that a sliding plate with the proportion of 12% of steel slag is closed.
The cold rolled base stock produced by the method of this example was found to have substantially normal overall surface quality, all [ O ] in steel: 26ppm, [ N ]:38ppm, the finished product has no problems of holes, cracking and the like caused by inclusion.
Example 3
A production method for smelting a thin cold-rolled base material under the high-pulling-speed condition comprises the following steps:
1) Pre-desulfurizing molten steel: endpoint [ S ]:0.001%;
2) Smelting molten steel by a decarburization converter: endpoint [ C ]:410ppm, T [ O ]:705ppm;
3) Tapping steel into a ladle: tapping temperature 1643 ℃ and tapping time 7min; tapping to stop slag, and no deoxidization alloying is performed in the tapping process;
4) Refining molten steel by adopting an RH furnace: vacuum treatment time is 14min, and pure degassing time is 10min; outbound [ Als ]:304ppm, out C:47ppm;
5) Refining molten steel by adopting an LF furnace:
a. refining time control: refining time is 65min;
b. and (3) process aluminum supplementing: and (3) strictly forbidden to supplement aluminum in 8min before calcium treatment, wherein the aluminum supplementing times are as follows: 3 times;
c. and (3) gas control: the whole process of LF refining is controlled by micro positive pressure, argon is protected in the wire feeding process, nitrogen is not increased in the process, and the process control meets the standard requirement;
d. soft blowing and calcium treatment: the soft blowing time is 12min before calcium treatment, 15min after calcium treatment, the wire feeding amount is 401m, and the outlet Ca/Als:0.085;
the chemical components of the obtained molten steel are as follows by mass percent: 0.015%, si:0.03%, mn:0.15%, P:0.012%, S:0.002%, al:0.024%, ca:0.0021%, N:0.0031% and the balance of Fe;
6) Protecting casting into a blank at a high pulling speed:
a. the ladle is poured by a low-position pouring method;
b. and (3) controlling the superheat degree of the ladle molten steel: degree of superheat of the tundish: 24 ℃, liquidus temperature 1534; DEG C
c. The ladle molten steel is not drained, and the casting process is increased by [ N ]:0ppm;
c. the water quantity of the crystallizer is automatically set according to the thickness of the wide-face and narrow-face copper plate, and forced cooling is adopted;
d. pulling speed: 5.1m/min, steel passing amount of tundish: 4.7t/min;
e. electromagnetic braking current: 130-150A, and the standard deviation control range of the fluctuation of the liquid level of the crystallizer is 0.3-1.6mm;
f. and the steel ladle electromagnetic induction slag discharging system is characterized in that a sliding plate with the proportion of 12% of steel slag is closed.
The cold rolled base stock produced by the method of this example was found to have substantially normal overall surface quality, all [ O ] in steel: 29ppm, [ N ]:31ppm, the finished product has no problems of holes, cracking and the like caused by inclusion.
To further illustrate the effects produced by the process, comparative analysis was performed on conventional processes and on casting blank samples of the process.
Comparative example 1
A production method for smelting a thin cold-rolled base material comprises the following steps: 1) Smelting molten steel by a decarburization converter; 2) Tapping steel from the ladle; 3) RH refining decarburization; 4) Refining molten steel by adopting an LF furnace, wherein the chemical components of the obtained molten steel are as follows by mass percent: 0.02%, si:0.02%, mn:0.16%, P:0.020%, S:0.004%, al:0.034%, ca:0.0015%, N:0.0043% and the balance Fe; 5) Protecting casting into blank with pulling speed not less than 4.5m/min.
Comparative example 2
A production method for smelting a thin cold-rolled base material comprises the following steps: 1) Smelting molten steel by a decarburization converter; 2) Tapping steel from the ladle; 3) RH refining decarburization; 4) Refining molten steel by adopting an LF furnace, wherein the chemical components of the obtained molten steel are as follows by mass percent: 0.03%, si:0.03%, mn:0.14%, P:0.016%, S:0.004%, al:0.035%, ca:0.0017%, N:0.0040% and the balance Fe; 5) Protecting casting into blank with pulling speed not less than 4.5m/min.
The experimental results are shown in the following table:
by comparison, the number of the inclusions is obviously reduced by adopting the method, the total amount of the inclusions is reduced by 31 percent, and particularly, the large-particle inclusions with the particle size more than 30 mu m are reduced by 93 percent, thereby greatly reducing the phenomena of holes, breakage and the like generated during the pressing and drawing of the product.
According to the embodiment, the high-rolling cold-rolled base material produced by the method under the high-pulling-speed condition can meet the production technical requirements of thin-specification strip steel and the requirements of maximization of customer profit.
Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The manufacturing method for smelting the thin cold-rolled base stock under the high-pulling-speed condition is characterized by comprising the following steps of:
1) Pre-desulfurizing molten steel;
2) Smelting molten steel by a decarburization converter;
3) Tapping steel to the steel ladle, wherein the tapping process is matched with a tapping slag blocking process, and deoxidation alloying is not performed;
4) Refining molten steel by adopting an RH furnace until the content of acid-soluble aluminum Als is 0.03-0.05 wt%;
5) Refining molten steel by adopting an LF furnace;
6) Protecting casting into blank with pulling speed not less than 4.5m/min.
2. The method for manufacturing a cold rolled base stock with thin gauge for smelting according to claim 1, wherein the S content of the molten steel obtained in the step 1) is 0.001-0.005 wt%; the C content of the molten steel in the step 2) is 0.04-0.07 wt% and the total oxygen content T [ O ] is 450-750 ppm; the C content of the molten steel obtained in the step 4) is less than or equal to 0.01 percent, and the step 4) adopts an aluminum-free deoxidizer to reduce the total oxygen content T [ O ] to 50ppm-350ppm after RH refining.
3. The method for manufacturing the smelting thin gauge cold rolled base stock according to claim 1, wherein the molten steel obtained in the step 5) comprises the following chemical components in percentage by mass: 0.01 to 0.04 percent, si:0 to 0.04 percent, mn:0.10 to 0.3 percent, P:0 to 0.020 percent, S:0 to 0.005 percent, al: 0.02-0.04%, ca:0.0010 to 0.0035 percent, N:0 to 0.0050 percent, and the balance being Fe.
4. The method for manufacturing a cold rolled base stock with thin gauge for smelting according to claim 1, wherein the tapping temperature in the step 3) is 1400-1650 ℃ and the tapping time is 4-9 min.
5. The method for manufacturing the smelting thin cold rolled base stock at the high pulling rate according to claim 1, wherein the highest vacuum degree in the RH refining process in the step 4) is less than or equal to 3mbar, the vacuum treatment time is 8-20 min, the pure degassing time is more than or equal to 6min, and the dosage of the aluminum-free deoxidizer is 0.3-0.5 kg/t.
6. The method for manufacturing a thin gauge cold rolled base stock by smelting at a high drawing speed according to claim 1, wherein the LF refining of step 5) includes a soft blowing and calcium treatment process: the wire feeding amount of the calcium treatment is 400+/-30 m/furnace, the soft blowing before the calcium treatment is carried out for 8-12 min, the soft blowing flow before the calcium treatment is 200-800 NL/min, the soft blowing after the calcium treatment is more than or equal to 12min, the soft blowing flow before the soft blowing after the calcium treatment is 200-600 NL/min, and the soft blowing flow after the calcium treatment is 80-220 NL/min, so that the Ca content of the obtained molten steel is more than or equal to 20ppm or Ca/Als is more than or equal to 0.08.
7. The method for manufacturing a thin gauge cold rolled base material smelted at a high drawing speed according to claim 6, wherein the LF refining time in the step 5) is 40-80 min; al is supplemented in the LF refining process to ensure that the Al content reaches 0.02-0.04 percent, and aluminum supplementing operation is not carried out in 8min before calcium treatment; the whole process of LF refining is controlled by micro positive pressure, the wire feeding process is protected by argon, and the process increment [ N ] < 10ppm.
8. The method for manufacturing a thin gauge cold rolled base stock for smelting at high drawing speed according to claim 1, wherein in the step 6), the ladle is protected for casting: the ladle molten steel is not drained, the [ N ] is increased to be less than or equal to 3ppm in the casting process, the normal full ladle casting tonnage of the tundish is more than 45t, and the steel passing amount of the tundish is less than or equal to 5.0t/min.
9. The method for manufacturing a cold rolled base stock with thin gauge smelting at high drawing speed according to claim 8, wherein in the step 6), the ladle tonnage in the cast steel is not lower than 2/3 of the full ladle; the low-carbon low-silicon high-alkalinity tundish covering agent is used, the slag alkalinity of an impact zone is more than 1.5, and FeO+MnO is less than 3%; the normal tonnage of the tundish is more than 45t.
10. The method for manufacturing the smelting thin cold rolled base stock at the high pulling speed according to claim 8, wherein the ladle adopts a low-position casting method; and (3) controlling the superheat degree of the middle ladle: 20-30 ℃; the water quantity of the crystallizer is automatically set according to the thickness of the wide-face narrow-face copper plate, the secondary cooling parameters are set according to the casting section, and forced cooling is adopted, so that the specific water quantity is more than or equal to 2.9l/kg; pulling speed: when the thickness of the casting blank is 70-90mm, the target pulling speed is 5.2+/-0.2 m/min; when the thickness of the casting blank is 90-110mm, the target pulling speed is 5.0 m+/-0.2/min; electromagnetic braking is adopted, the current intensity is 145+/-15A, and the standard deviation of fluctuation of the liquid level of the crystallizer is less than or equal to 2.5mm; and a ladle electromagnetic induction slag discharging system is adopted, and a sliding plate with the proportion of steel slag reaching 12-30% is automatically closed.
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