CN112921237A - Smelting method of silicon-manganese killed non-oriented silicon steel - Google Patents
Smelting method of silicon-manganese killed non-oriented silicon steel Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 58
- 229910000976 Electrical steel Inorganic materials 0.000 title claims abstract description 38
- 238000003723 Smelting Methods 0.000 title claims abstract description 35
- PYLLWONICXJARP-UHFFFAOYSA-N manganese silicon Chemical compound [Si].[Mn] PYLLWONICXJARP-UHFFFAOYSA-N 0.000 title claims abstract description 30
- 239000002893 slag Substances 0.000 claims abstract description 73
- 239000010959 steel Substances 0.000 claims abstract description 70
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 67
- 230000008569 process Effects 0.000 claims abstract description 28
- 238000005275 alloying Methods 0.000 claims abstract description 27
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910052593 corundum Inorganic materials 0.000 claims abstract description 21
- 229910001845 yogo sapphire Inorganic materials 0.000 claims abstract description 21
- 238000009749 continuous casting Methods 0.000 claims abstract description 16
- 238000010079 rubber tapping Methods 0.000 claims abstract description 16
- 238000005261 decarburization Methods 0.000 claims abstract description 13
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 12
- 239000012535 impurity Substances 0.000 claims abstract description 12
- 238000004519 manufacturing process Methods 0.000 claims abstract description 12
- 238000007670 refining Methods 0.000 claims abstract description 12
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 11
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims abstract description 10
- 235000011941 Tilia x europaea Nutrition 0.000 claims abstract description 10
- 239000004571 lime Substances 0.000 claims abstract description 10
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 10
- 239000011572 manganese Substances 0.000 claims abstract description 10
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 6
- 239000000126 substance Substances 0.000 claims abstract description 4
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 37
- 229910052742 iron Inorganic materials 0.000 claims description 18
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 15
- 229910052760 oxygen Inorganic materials 0.000 claims description 15
- 239000001301 oxygen Substances 0.000 claims description 15
- 229910052751 metal Inorganic materials 0.000 claims description 14
- 239000002184 metal Substances 0.000 claims description 14
- 239000007789 gas Substances 0.000 claims description 12
- 229910052782 aluminium Inorganic materials 0.000 claims description 9
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 9
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 8
- 229910000519 Ferrosilicon Inorganic materials 0.000 claims description 7
- 239000011593 sulfur Substances 0.000 claims description 6
- 229910045601 alloy Inorganic materials 0.000 claims description 4
- 239000000956 alloy Substances 0.000 claims description 4
- 229910052791 calcium Inorganic materials 0.000 claims description 4
- 239000011575 calcium Substances 0.000 claims description 4
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 3
- 238000007664 blowing Methods 0.000 claims description 3
- 229910001634 calcium fluoride Inorganic materials 0.000 claims description 3
- 238000006477 desulfuration reaction Methods 0.000 claims description 2
- 230000023556 desulfurization Effects 0.000 claims description 2
- 230000001681 protective effect Effects 0.000 claims description 2
- 238000005086 pumping Methods 0.000 claims description 2
- 238000003756 stirring Methods 0.000 claims description 2
- 229910006639 Si—Mn Inorganic materials 0.000 claims 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 abstract description 17
- 229910052681 coesite Inorganic materials 0.000 abstract description 15
- 229910052906 cristobalite Inorganic materials 0.000 abstract description 15
- 239000000377 silicon dioxide Substances 0.000 abstract description 15
- 229910052682 stishovite Inorganic materials 0.000 abstract description 15
- 229910052905 tridymite Inorganic materials 0.000 abstract description 15
- 239000011819 refractory material Substances 0.000 abstract description 10
- 238000005096 rolling process Methods 0.000 abstract description 9
- 238000002844 melting Methods 0.000 abstract description 8
- 230000008018 melting Effects 0.000 abstract description 8
- 230000003749 cleanliness Effects 0.000 abstract description 5
- 230000002378 acidificating effect Effects 0.000 abstract description 4
- 239000013078 crystal Substances 0.000 abstract description 4
- 230000003628 erosive effect Effects 0.000 abstract description 4
- 230000007797 corrosion Effects 0.000 abstract description 2
- 238000005260 corrosion Methods 0.000 abstract description 2
- 238000005266 casting Methods 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 4
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- 239000000463 material Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 238000010587 phase diagram Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 239000002253 acid Substances 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000007667 floating Methods 0.000 description 2
- 238000005098 hot rolling Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 229910000616 Ferromanganese Inorganic materials 0.000 description 1
- 229910000655 Killed steel Inorganic materials 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 229910000720 Silicomanganese Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000010436 fluorite Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 description 1
- 229910001004 magnetic alloy Inorganic materials 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
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- 238000012545 processing Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000009991 scouring Methods 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Inorganic materials [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
-
- 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
- C21C7/0006—Adding metallic additives
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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
- C21C7/0087—Treatment of slags covering the steel bath, e.g. for separating slag from the molten metal
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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
-
- 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
- C21C7/068—Decarburising
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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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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
- C22C33/06—Making ferrous alloys by melting using master alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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Abstract
The invention provides a smelting method of silicon-manganese killed non-oriented silicon steel. The non-oriented silicon steel comprises the following chemical components in percentage by mass of less than or equal to 0.005% of C, Si: 0.25% -1.20%, Mn: 0.2% -0.8%, P: 0.015-0.065%, S is less than or equal to 0.005%, Als is less than or equal to 0.005%, and the balance is Fe and inevitable impurities. The production method comprises the steps of adding lime after tapping of the converter, and slag surface deoxidizing agent slag adjustment; and (3) deoxidizing and alloying after the RH vacuum refining decarburization is finished, adding synthetic slag from a vacuum chamber bin 3-5min after alloying, carrying out net circulation for 8-12min after a period of treatment, and conveying the vacuum-broken steel to continuous casting and pouring. The obtained molten steel is mainly SiO2‑CaO‑Al2O3Is mixed, on one hand, the generation of low melting point SiO in molten steel is avoided2MnO series inclusions exist, and the rolling process extends along the rolling direction to block the growth of crystal grains; on the other hand, the generation of pure SiO is also avoided2Or high SiO2The acidic inclusion of the components causes severe erosion of the refractory material during smelting. The invention can control the type of non-metallic inclusion in steel, improve the cleanliness of molten steel and improve the corrosion to refractory materials in the smelting process.
Description
Technical Field
The invention belongs to the technical field of steel smelting, and particularly relates to a smelting method of silicon-manganese killed non-oriented silicon steel.
Background
The silicon-manganese killed non-oriented silicon steel is a soft magnetic alloy, is an indispensable energy-saving functional material in national power, electronics and military industries, is mainly applied to iron cores of various household motors, compressors, generators, ballasts and transformers, plays a role of a medium for electromagnetic energy conversion, plays an important role in energy conservation and consumption reduction, and is closely related to national economic development and people life. The prior non-oriented silicon steel smelting process flow is as follows: KR molten iron pretreatment → converter → RH vacuum furnace refining → continuous casting.
The silicon-manganese killed non-oriented silicon steel requires strict acid-soluble aluminum in a finished product, and the content of the acid-soluble aluminum is controlled to be below 0.0050 percent, so that ultra-low-carbon low-sulfur silicon iron and manganese metal are adopted for deoxidation alloying in the production process. When ferrosilicon, ferromanganese and other alloys are used for oxygen alloying, the deoxidation product is mainly SiO with low melting point2-MnO inclusions, the MnO content being between 5% and 25%, the MnO melting point being low, the MnO content of the oxide composite inclusions being high, being in a semi-molten state at higher temperature of hot rolling, andthe silicon-manganese killed non-oriented silicon steel is elongated along the rolling direction, and the growth of crystal grains can be hindered during annealing, so that the magnetic property of the series of silicon-manganese killed non-oriented silicon steel is reduced. In order to solve the problem, patent CN108660294B introduces a method for controlling inclusions in silicon-manganese killed silicon steel, which controls the inclusions to be high SiO2Zone, pure SiO produced by deoxidation alloying in molten steel2Or high SiO2The component-classified high-melting-point acid inclusion has small inhibition effect on crystal grains although not deformed in the rolling process, but because SiO in the inclusion2The content of the components is too high, and the materials of the vacuum furnace refractory, the continuous casting water gap, the stopper rod and the like are generally MgO and Al2O3Material, high SiO2The components are mixed and react with refractory materials to produce low-melting-point silicate products, and the refractory materials are seriously eroded under the scouring action of molten steel, so that the quality of the molten steel and the normal operation of production are influenced.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a smelting method of silicon-manganese killed non-oriented silicon steel, which has the following specific technical scheme:
a smelting method of silicon-manganese killed non-oriented silicon steel comprises the following chemical components in percentage by mass, C is less than or equal to 0.005%, Si: 0.25% -1.20%, Mn: 0.2% -0.8%, P: 0.015-0.065%, S less than or equal to 0.005%, Als less than or equal to 0.005%, and the balance Fe and inevitable impurities. The production method of the silicon-manganese killed non-oriented silicon steel sequentially comprises a KR molten iron pretreatment process, a converter smelting process, an RH vacuum refining process and a continuous casting process, wherein the KR molten iron pretreatment process, the converter smelting process, the RH vacuum refining process and the continuous casting process are sequentially carried out, and the method comprises the following steps of:
(1) KR molten iron pretreatment: the S content is less than or equal to 0.002 percent after the molten iron is desulfurized;
(2) strictly controlling the slag discharge amount during converter tapping, simultaneously adding lime and a slag surface deoxidizer to the surface of molten steel after tapping is finished to control oxygen and adjust slag, and then conveying to RH treatment;
(3) RH deep decarburization treatment, after the deep decarburization treatment, firstly adding low-carbon low-sulfur ferrosilicon for deoxidation alloying, simultaneously adding a slag surface deoxidizing agent into the slag surface of a steel ladle to deoxidize and modify the slag, after circulating for 3-5min, adding metal manganese and ferrophosphorus for alloying, after alloying, adding synthetic slag from a vacuum chamber bin 3-5min, reducing the flow rate of lifting gas when adding the synthetic slag, simultaneously closing two-stage vacuum pumps E4 and E5 to reduce the air pumping capacity, after circulating for 4-6min, recovering the flow rate of the lifting gas, and restarting the two-stage vacuum pumps E4 and E5 to carry out clean circulation treatment, wherein the clean circulation treatment time is 8-12min, then breaking the air and tapping;
(4) and after RH refining is finished, the molten steel is hoisted to continuous casting for protective pouring.
Further, in the smelting method of silicon-manganese killed non-oriented silicon steel, the KR station molten iron condition meets the following conditions: the temperature is more than or equal to 1360 ℃, Si is more than or equal to 0.20% and less than or equal to 0.45%, and S is less than or equal to 0.045%;
furthermore, after the tapping of the converter is finished, 1.5-3.0kg/t of lime, 0.5-2.0kg/t of slag surface deoxidizer and 1000NL/min of ladle bottom blowing flow rate are added to the surface of the molten steel and stirred for 4-6 min.
Furthermore, in the smelting method of the silicon-manganese killed non-oriented silicon steel, the free oxygen content of RH incoming molten steel is controlled to be 0.045-0.065%, and the free oxygen content of the molten steel is less than or equal to 0.035% after RH decarburization is finished.
Furthermore, in the smelting method of the silicon-manganese killed non-oriented silicon steel, 5.5-15.5kg/t of low-carbon low-sulfur silicon iron is added into molten steel after RH decarburization is finished, and 0.5-1.0kg/t of slag surface deoxidizer is added into the slag surface of the steel ladle to modify the slag, wherein the slag surface deoxidizer mainly comprises the following components in percentage by mass: 35% -45% of Al2O3: 25% -35%, metal aluminum: 20% -35% of CaF2: 3-8 percent of the alloy, and other inevitable impurities, and finally adding metal manganese and ferrophosphorus for alloying.
Furthermore, the smelting method of the silicon-manganese killed non-oriented silicon steel is characterized in that 1.0-2.5kg/t of synthetic slag is added from a vacuum chamber bin 3-5min after RH alloying is finished, and the main components of the synthetic slag comprise CaO: 60% -70% of Al2O3: 10% -15%, calcium metal: 10-15%, metallic aluminum: 5% -10% and other inevitable impurities.
Furthermore, in the smelting method of the silicon-manganese killed non-oriented silicon steel, the flow rate of the lifting gas is set to be 90-110NL/min when RH synthesized slag is added, the vacuum pumps E4 and E5 are closed, the pressure of the vacuum chamber is increased to 350mbar when the pressure of the vacuum chamber is increased to 100-.
Furthermore, in the smelting method of the silicon-manganese killed non-oriented silicon steel, RH net circulation treatment time is 8-12min, and then the steel is tapped after the space is broken.
Furthermore, the inclusion in the molten steel smelted by the silicomanganese killed non-oriented silicon steel smelting method is SiO2-CaO-Al2O3Is SiO in the inclusions2≤60％、Al2O3Less than or equal to 25 percent, CaO: 20-50% and small amount of other inevitable components.
The design principle of the invention is as follows:
after tapping, lime and a slag surface deoxidizer are added to carry out slag adjustment and deoxidation, and the oxidizability of slag and the oxygen content of molten steel when RH enters the station are controlled. After RH vacuum deep decarburization, the oxygen content of molten steel is ensured to be controlled at a lower level (below 0.035%), then low-carbon low-sulfur ferrosilicon is added for deoxidation alloying, simultaneously slag surface deoxidizer is added to the slag surface of steel ladle for deoxidation modification of slag, and SiO generated during deoxidation alloying2The total amount of SiO remained in the molten steel is relatively reduced2The inclusions are also correspondingly reduced; meanwhile, the oxidability of the slag is very low, and the manganese metal is added after the circulation for 3-5min and hardly oxidized, so that SiO is effectively controlled2Formation of MnO Low melting inclusions. After finishing the RH alloying, adding high-alkalinity synthetic slag into the molten steel in the vacuum chamber, simultaneously increasing the pressure in the RH vacuum chamber, reducing and improving the gas flow, namely weakening the circulating flow of the molten steel, prolonging the retention time of the synthetic slag in the molten steel, and promoting CaO and Al in the synthetic slag2O3Component and SiO2Carrying out sufficient reaction; the synthetic slag contains proper amount of metal Ca and Al, SiO in molten steel2The modification and reduction of the inclusion surface layer also enhances the deoxidation of the molten steel, comprehensively reduces the total oxygen content of the molten steel, improves the cleanliness of the molten steel, and controls the inclusion in the molten steel to be SiO2-CaO-Al2O3Is an inclusion of SiO as the main component2≤60％、Al2O3Less than or equal to 25 percent, CaO: 20 to 50 percent, and avoids generating pure SiO2Or high SiO2The acidic inclusion of the components causes severe erosion of the refractory material during smelting. Designing proper synthetic slag components, and well controlling the SiO which is the original deoxidation product of molten steel2Inclusion modified components and their contents. Strictly controlling the cycle time after reducing the pressure of the vacuum chamber and increasing the gas flow after adding the synthetic slag, and ensuring the synthetic slag and SiO2After the full mixing reaction, the gas flow and the pressure of the vacuum chamber are immediately recovered and improved, the circulation flow is increased, the floating of the synthetic slag and large-size impurities is promoted, and the net circulation time under the set circulation flow is also strictly controlled, because the component in the synthetic slag and the SiO which is the original deoxidation product of the molten steel can be caused by the over-small circulation flow and the over-long treatment time of the molten steel after the synthetic slag is added2Excessive reaction to result in CaO and Al inclusions2O3Too high, the melting point of the inclusions is raised and deviates from the target area; if the circulating flow of the molten steel is too large and the processing time is too short, the synthetic slag component and SiO2The reaction is insufficient, the inclusion is still an acidic high SiO2 component, and the corrosion to the refractory is still serious, so that the circulation amount and the treatment time after the synthetic slag is added are too long or too short, and the inclusion can not be ensured to fall on the target of component design. In addition, SiO formed after modification2-CaO-Al2O3The system has larger inclusion size, improves the RH vacuum degree and the gas flow in the later period, increases the molten steel circulation flow, is more beneficial to floating and removing the inclusion, and improves the molten steel cleanliness.
Compared with the prior art, the invention has at least the following beneficial effects:
1. the invention provides a method for accurately controlling impurities in molten steel to be SiO2-CaO-Al2O3Method of inclusion, main component SiO2≤60％、Al2O3Less than or equal to 25 percent, CaO: 20-50 percent, proper melting point, no water gap blockage in the casting process, difficult deformation in the rolling process and avoidance of SiO with low melting point generated2The rolling elongation of the inclusion caused by MnO inclusion is prolonged, and the grain growth is influenced; simultaneously reduces the generation of pure SiO2Or high SiO2The acidic inclusion of the components causes the serious erosion of refractory materials in the smelting process, thereby improving the performance and the production stability of the series of silicon-manganese killed non-oriented silicon steel.
2. The invention modifies molten steel and slag three times in the processes of converter tapping, RH refining and alloying, can accurately control the oxidability of the molten steel and the slag, and obviously reduces the alloy consumption in the alloying process compared with the conventional process.
3. The inclusion type and the smelting process controlled by the invention effectively reduce the erosion of refractory materials and reduce the consumption of the refractory materials, and are very beneficial to the control of production cost and environmental protection.
Drawings
FIG. 1 shows SiO inclusions in steel after the technical scheme of the invention is adopted2-CaO-Al2O3Is a distribution diagram in a ternary phase diagram.
FIG. 2 shows that the inclusions in the steel are in SiO state in the original process2-Al2O3-MnO is a distribution diagram in ternary phase diagram.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Examples
The production of the silicon-manganese killed non-oriented silicon steel is carried out on a production line of the non-oriented silicon steel in a certain steel mill. The process flow comprises the following steps: KR molten iron pretreatment → converter smelting → RH vacuum refining → continuous casting. The invention will be further explained by taking the process treatment of the invention as an example.
(1) The molten iron is subjected to KR desulfurization treatment, and the molten iron requirements for entering and leaving are shown in the following table 1. After the treatment is finished, the mixture is transported to a converter for converting.
TABLE 1 KR inbound and outbound molten iron conditions
| Furnace number | The arrival temperature, deg.C | Si，％ | Pre S% | Post S% |
| 1 | 1360 | 0.20 | 0.026 | 0.0011 |
| 2 | 1377 | 0.33 | 0.030 | 0.0015 |
| 3 | 1386 | 0.45 | 0.045 | 0.0020 |
(2) The slag discharge amount is strictly controlled during converter tapping, and lime and a slag surface deoxidizer are added into steel after tapping to control oxygen and adjust slag. The addition of slag surface deoxidizer and lime and other process parameters are shown in the following table 2, and after the slag is uniformly melted, water is transported to RH for smelting.
TABLE 2 converter smelting Process parameters
| Furnace number | Lime, kg/t | Slag surface deoxidizer, kg/t | Ladle bottom blowing flow rate, NL/min | Stirring time, min |
| 1 | 1.5 | 0.5 | 700 | 4 |
| 2 | 3.0 | 1.1 | 1000 | 5 |
| 3 | 2.6 | 2.0 | 850 | 6 |
(3) The RH inbound free oxygen content is controlled to be 0.045% -0.065%; after the decarburization is finished, the free oxygen content of the molten steel is less than or equal to 0.035%; after the deep decarburization is finished, the low-carbon low-sulfur ferrosilicon is added, and simultaneouslyAdding a slag surface deoxidizer into the slag surface of the steel ladle to deoxidize and modify the slag, wherein the used slag surface deoxidizer comprises the following main components in percentage by mass: CaO: 35% -45% of Al2O3: 25% -35%, metal aluminum: 20% -35% of CaF2: 3-8%, and other unavoidable impurities; and after circulation is carried out for 3-5min, adding metal manganese and ferrophosphorus for alloying, adding synthetic slag from a bin of the vacuum chamber 3-5min after alloying is finished, setting the flow of lifting gas to be 90-110NL/min during adding the synthetic slag, simultaneously closing E4 and E5 vacuum pumps, increasing the pressure of the vacuum chamber to 350mbar of 100 organic chemical reagents, after treatment is carried out for 4-6min, opening E4 and E5 vacuum pumps, recovering the flow of the lifting gas to 210NL/min of 190 organic chemical reagents, reducing the pressure of the vacuum chamber to be below 2mbar, carrying out clean circulation treatment, wherein the clean circulation time is 8-12min, and then breaking and tapping. The used synthetic slag comprises the following main components in percentage by mass: 60% -70% of Al2O3: 10% -15%, calcium metal: 10-15%, metallic aluminum: 5% -10% and other inevitable impurities. Other process parameters are shown in table 3 below.
TABLE 3 RH vacuum refining Process parameters
(4) And after the RH vacuum refining is finished, the molten steel is lifted to a continuous casting station for casting, and the whole-process protection casting is adopted.
The ultralow-aluminum non-oriented silicon steel obtained by the method comprises the following chemical components in percentage by mass: c: 0.0013% -0.005%, Si: 0.25% -1.20%, Mn: 0.2% -0.8%, P: 0.015% -0.065%, S: 0.0012 to 0.005 percent of Al, 0.0015 to 0.005 percent of Als and the balance of Fe and inevitable impurities.
In the continuous casting process, a crystallizer molten steel sample is taken to analyze the components of inclusions, and the main type of oxide inclusions in the steel is SiO2-CaO-Al2O3Is SiO in the inclusions2≤60％、Al2O3Less than or equal to 25 percent, CaO: 20% -50%, and small amount of other inevitable components, and the distribution in the phase diagram is shown in figure 1.
Comparative examples
The original production process of the series of silicon-manganese killed non-oriented silicon steel comprises the following steps: KR molten iron pretreatment → converter smelting → RH refining → continuous casting. Slag stopping balls are adopted for slag stopping and tapping in converter tapping, the slag discharging amount is strictly controlled, and lime and fluorite are added for slagging after tapping is finished; after the RH vacuum is treated by adopting a deep decarburization process, two schemes are adopted in the deoxidation alloying process, namely a scheme 1: simultaneously adding low-carbon low-sulfur ferrosilicon, metal manganese and ferrophosphorus for deoxidation alloying, after the deoxidation alloying is finished, the molten steel is completely circulated for more than 6min, and then the air is broken, the steel is tapped, and the molten steel is transported to a continuous casting platform for casting. The obtained inclusion is shown as region 1 in FIG. 2, and the main type of the inclusion is SiO2-MnO、SiO2-MnO-Al2O3Wherein the MnO component is higher and accounts for 30-60 percent, the melting point of MnO is low, the MnO content in the oxide composite inclusions is high, the oxide composite inclusions are in a semi-molten state during hot rolling at a higher temperature and extend along the rolling direction, and crystal grains can be prevented from growing during annealing, so that the magnetic performance of the series of ultra-low aluminum non-oriented silicon steel is reduced. Scheme 2: the low-carbon low-sulfur ferrosilicon is added for deoxidation, after the oxygen content of the molten steel is fully removed, the metal manganese, ferrophosphorus and the like are added for deoxidation alloying, after the deoxidation alloying is finished, the molten steel is circulated for more than 6min, and then the hollow part is broken, the steel is tapped, and the molten steel is transported to a continuous casting platform for casting. The resulting inclusion is shown as region 2 in FIG. 2, where SiO is2The components are higher, the percentage of the components is more than 70 percent, the inclusions are not deformed in the rolling process, the influence on the grain growth in the cold rolling annealing stage is less, but pure SiO2Or high SiO2The group classification acid inclusions seriously erode refractory materials of a steel ladle and an RH vacuum furnace, and are not beneficial to the improvement of the quality of molten steel and the stability of the pouring performance. The two production schemes are implemented in industrial production, and the production stability of the silicon-manganese killed steel is not ideally controlled due to different problems.
Through comparison between the embodiment and the comparative embodiment, the inclusion type controlled by the invention can ensure the pouring performance of molten steel, does not erode refractory materials of a vacuum furnace and continuous casting equipment, increases the number of continuous casting furnaces from the original 10-12 furnaces to 14-46 furnaces, and increases the service life of an RH dip pipe from the original 80-100 times to 120-135 times; meanwhile, because the high-alkalinity synthetic slag is added from the vacuum chamber, the deoxidation of the molten steel is enhanced, the free oxygen is reduced to below 25ppm from the original 40-65ppm, and the cleanliness is greatly improved. The type control and the cleanliness improvement of the inclusions are integrated, the number of the inclusions is reduced, the inclusions cannot deform in the rolling process, the performance of the silicon steel is stable, and the standard reaching rate of the magnetic performance of the silicon steel is improved to more than 97% from the original 92%.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered as the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.
Claims (9)
1. A smelting method of silicon-manganese killed non-oriented silicon steel comprises the following chemical components in percentage by mass, C is less than or equal to 0.005%, Si: 0.25% -1.20%, Mn: 0.2% -0.8%, P: 0.015-0.065%, S is less than or equal to 0.005%, Als is less than or equal to 0.005%, and the balance of Fe and inevitable impurities; the production method of the silicon-manganese killed non-oriented silicon steel is characterized by comprising a KR molten iron pretreatment process, a converter smelting process, an RH vacuum refining process and a continuous casting process which are sequentially carried out, wherein:
(1) in the KR molten iron pretreatment procedure, the S content is less than or equal to 0.002 percent after molten iron desulfurization treatment;
(2) strictly controlling the slag discharge amount during converter tapping, simultaneously adding lime and a slag surface deoxidizer to the surface of molten steel after tapping is finished to control oxygen and adjust slag, and then conveying to RH treatment;
(3) RH deep decarburization treatment, after the deep decarburization treatment, firstly adding low-carbon low-sulfur ferrosilicon for deoxidation alloying, simultaneously adding a slag surface deoxidizing agent into the slag surface of a steel ladle to deoxidize and modify the slag, after circulating for 3-5min, adding metal manganese and ferrophosphorus for alloying, after alloying, adding synthetic slag from a vacuum chamber bin 3-5min, reducing the flow rate of lifting gas when adding the synthetic slag, simultaneously closing two-stage vacuum pumps E4 and E5 to reduce the air pumping capacity, after circulating for 4-6min, recovering the flow rate of the lifting gas, and restarting the two-stage vacuum pumps E4 and E5 to carry out clean circulation treatment, wherein the clean circulation treatment time is 8-12min, then breaking the air and tapping;
(4) and after RH refining is finished, the molten steel is hoisted to continuous casting for protective pouring.
2. The smelting method of silicon-manganese killed non-oriented silicon steel as claimed in claim 1, wherein the molten iron condition of KR entering station meets the following requirements: the temperature is more than or equal to 1360 ℃, Si is more than or equal to 0.20 percent and less than or equal to 0.45 percent, and S is less than or equal to 0.045 percent.
3. The smelting method of silicon-manganese killed non-oriented silicon steel as claimed in claim 1, wherein lime is added to the surface of molten steel at a ratio of 1.5-3.0kg/t, slag surface deoxidizer is added at a ratio of 0.5-2.0kg/t, ladle bottom blowing flow is 700-1000NL/min, and stirring is carried out for 4-6 min.
4. The smelting method of silicon-manganese killed non-oriented silicon steel as claimed in claim 1, wherein the free oxygen content in RH incoming molten steel is controlled to be 0.045% -0.065%, and the free oxygen content in RH decarburization finished molten steel is less than or equal to 0.035%.
5. The smelting method of silicon-manganese killed non-oriented silicon steel as claimed in claim 1, wherein 5.5-15.5kg/t of low-carbon low-sulfur silicon iron is added into the molten steel after RH decarburization is finished, and 0.5-1.0kg/t of slag surface deoxidizer is added into the slag surface of the steel ladle to modify the slag, wherein the slag surface deoxidizer mainly comprises the following components in percentage by mass: 35% -45% of Al2O3: 25% -35%, metal aluminum: 20% -35% of CaF2: 3-8 percent of the alloy, and other inevitable impurities, and finally adding metal manganese and ferrophosphorus for alloying.
6. The smelting method of silicon-manganese killed non-oriented silicon steel as claimed in claim 1, wherein 1.0-2.5kg/t of synthetic slag is added from a vacuum chamber bin 3-5min after RH alloying is finished, and the main components of the synthetic slag are CaO: 60% -70% of Al2O3: 10% -15%, calcium metal: 10-15%, metallic aluminum:5% -10% and other inevitable impurities.
7. The method as claimed in claim 1, wherein the lift gas flow rate during RH synthetic slag addition is set to 90-110NL/min, the vacuum pumps E4 and E5 are turned off, the pressure in the vacuum chamber is increased to 350mbar within 100-.
8. The smelting method of silicon-manganese killed non-oriented silicon steel as claimed in claim 1, wherein RH net cycle treatment time is 8-12min, then the hole is broken and steel is tapped.
9. The smelting method of Si-Mn killed non-oriented silicon steel as claimed in claim 1 to 7, wherein the inclusion in the molten steel is SiO2-CaO-Al2O3Is SiO in the inclusions2≤60％、Al2O3Less than or equal to 25 percent, CaO: 20-50% and small amount of other inevitable components.
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