CN113462981A - Continuous annealing low alloy steel HC500LA and smelting method thereof - Google Patents
Continuous annealing low alloy steel HC500LA and smelting method thereof Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 44
- 238000000137 annealing Methods 0.000 title claims abstract description 31
- 229910000851 Alloy steel Inorganic materials 0.000 title claims abstract description 29
- 238000003723 Smelting Methods 0.000 title claims abstract description 29
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 66
- 239000010959 steel Substances 0.000 claims abstract description 66
- 239000000126 substance Substances 0.000 claims abstract description 18
- 238000009749 continuous casting Methods 0.000 claims abstract description 12
- 239000012535 impurity Substances 0.000 claims abstract description 12
- 238000007670 refining Methods 0.000 claims abstract description 7
- 239000002893 slag Substances 0.000 claims description 21
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 20
- 239000003607 modifier Substances 0.000 claims description 14
- 238000007664 blowing Methods 0.000 claims description 13
- 238000010079 rubber tapping Methods 0.000 claims description 13
- 239000011575 calcium Substances 0.000 claims description 12
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 11
- 229910052791 calcium Inorganic materials 0.000 claims description 11
- 229910052786 argon Inorganic materials 0.000 claims description 10
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 8
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 8
- 239000004571 lime Substances 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 7
- 229910052717 sulfur Inorganic materials 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 229910052758 niobium Inorganic materials 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 claims description 4
- 229910014813 CaC2 Inorganic materials 0.000 claims description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 3
- 150000001669 calcium Chemical class 0.000 claims description 3
- 229910001634 calcium fluoride Inorganic materials 0.000 claims description 3
- 229910052593 corundum Inorganic materials 0.000 claims description 3
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- 229910052698 phosphorus Inorganic materials 0.000 claims description 3
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 3
- 238000005266 casting Methods 0.000 abstract description 15
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- 238000009851 ferrous metallurgy Methods 0.000 abstract description 2
- 238000005336 cracking Methods 0.000 abstract 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 9
- 239000011572 manganese Substances 0.000 description 9
- 239000010936 titanium Substances 0.000 description 9
- 239000010955 niobium Substances 0.000 description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
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- 239000000956 alloy Substances 0.000 description 5
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- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
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- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
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- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
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- 238000001179 sorption measurement Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
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- 238000010521 absorption reaction Methods 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 239000010436 fluorite Substances 0.000 description 1
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- 238000010438 heat treatment Methods 0.000 description 1
- -1 high-manganese Inorganic materials 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
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- 238000002844 melting Methods 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
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- 238000009628 steelmaking Methods 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/072—Treatment with gases
-
- 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
- C21C7/076—Use of slags or fluxes as treating agents
-
- 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
-
- 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
-
- 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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- 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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- 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
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
-
- 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
Abstract
The invention discloses continuous annealing low alloy steel HC500LA and a smelting method thereof, belonging to the technical field of ferrous metallurgy. The continuous annealing low alloy steel HC500LA comprises the following chemical components in percentage by mass: 0.06-0.08% of C, 0.12-0.18% of Si, 1.20-1.30% of Mn, less than or equal to 0.015% of P, less than or equal to 0.005% of S, 0.050-0.060% of Nb, 0.030-0.040% of Ti, 0.015-0.050% of Als, and the balance of Fe and inevitable impurities. The smelting method of the continuous annealing low alloy steel HC500LA can effectively improve the cleanliness of molten steel and reduce the longitudinal cracking proportion of the casting blank corner by controlling the processes of converter smelting, LF refining and continuous casting, so that the smelting rate of the continuous annealing low alloy steel HC500LA is improved to more than 95% from less than 80% in the early stage, and the problem of lower smelting rate of the continuous annealing low alloy steel HC500LA in the prior art can be effectively solved.
Description
Technical Field
The invention belongs to the technical field of ferrous metallurgy, and particularly relates to continuous annealing low alloy steel HC500LA and a smelting method thereof.
Background
With the progress of science and technology, the requirements for energy conservation and emission reduction become stricter and the use of high-strength steel tends to be mainstream. Compared with the traditional continuous annealing product, the continuous annealing low alloy steel has the advantages of high strength, good plasticity, good formability and the like, and is suitable for structural components with high strength requirements of automobiles.
Patent CN111826578A of 10, 27/2020 discloses 420 MPa-grade cold-rolled low-alloy high-strength steel and a manufacturing method thereof, wherein the chemical components of the steel are 0.06-0.08% of C, 0.08-0.13% of Si, 1.00-1.10% of Mn, less than or equal to 0.018% of P, less than or equal to 0.005% of S, 0.020-0.050% of Alt, 0.040-0.050% of Nb, 0.020-0.0.030% of Ti, 0.0010-0.0030% of Ca, less than or equal to 50ppm of N, and the balance of Fe and inevitable impurities. The steel-making process comprises the following steps: KR pre-desulfurized molten iron is adopted, deoxidation alloying is carried out in the smelting process of a converter, the tapping temperature is more than or equal to 1620 ℃, LF refining slagging desulfurization is carried out, the components are adjusted to a target range, calcium treatment is carried out after the LF treatment is finished, and the soft blowing time is ensured to be more than 8 minutes after the calcium treatment; and (3) during continuous casting, the superheat degree delta T of the ladle molten steel in the first furnace is as follows: 25-40 ℃, superheat degree delta T of other molten steel: the drawing speed is 1.0-1.5m/min at 15-30 ℃, and the drawing speed is controlled constantly. The strength level of the invention is lower; the calcium treatment process is adopted in the smelting, so that the cost is high; the superheat degree of continuous casting is slightly high, and the segregation of a casting blank is slightly unfavorable; there is no relevant requirement for the crystallizer, and the quality control of the surface of the plate blank, especially the quality control of the corner part, can not reach the requirement of the invention.
The continuous annealing low alloy steel HC500LA is designed by adopting low-carbon, high-manganese, niobium and titanium components, and compared with the traditional steel for the continuous annealing automobile structural part, the strength is improved, and the good plasticity and formability are ensured. The performance of the casting blank is guaranteed, and meanwhile, strict requirements are provided for the quality of the mother material, namely cleanliness and casting blank quality control. But the smelting yield of the continuous annealing low alloy steel HC500LA in the prior art is lower (less than 80%), mainly because the cleanliness of molten steel is poor, the nitrogen content often exceeds the standard, the inclusion degradation rate of a cold-rolled coil is up to more than 10%, and the longitudinal crack ratio of the corner of a casting blank is high, so that the yield of rolled products is lower.
Disclosure of Invention
The invention aims to solve the technical problem that the smelting yield of smelting continuous annealing low alloy steel HC500LA is low in the prior art.
The technical scheme adopted by the invention for solving the technical problems is as follows: the continuous annealing low alloy steel HC500LA comprises the following chemical components in percentage by mass: 0.06-0.08% of C, 0.12-0.18% of Si, 1.20-1.30% of Mn, less than or equal to 0.015% of P, less than or equal to 0.005% of S, 0.050-0.060% of Nb, 0.030-0.040% of Ti, 0.015-0.050% of Als, and the balance of Fe and inevitable impurities.
The smelting method of the continuous annealing low alloy steel HC500LA comprises the following steps:
a. a converter smelting process: controlling the converter to enter molten steel]Not more than 0.003 percent of the total content of the components, and the content of [ C ] in the molten steel at the end point of the converter]0.03-0.05 percent of steel tapping process, adding active lime in the steel tapping process, adding a calcium top slag modifier to the slag surface after the steel tapping process is finished, wherein the chemical component of the furnace calcium top slag modifier is CaC2 30-50％，Al2O3 10-30％，CaO 20-40％，CaF28-15%, S is less than or equal to 0.2, P is less than or equal to 0.1, and the balance is inevitable impurities;
and b, LF refining: controlling the chemical components of the molten steel to be 0.06-0.08 percent of C, 0.12-0.18 percent of Si, 1.20-1.30 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, 0.050-0.060 percent of Nb, 0.030-0.040 percent of Ti, 0.015-0.050 percent of Als and the balance of Fe and inevitable impurities, and carrying out soft blowing by adopting argon before the molten steel is discharged;
c. and (3) continuous casting process: controlling the superheat degree of the molten steel in the continuous casting tundish to be 20-35 ℃, adopting a chamfering crystallizer, applying soft reduction and pulling speed to be 0.9-1.3 m/min.
In the step a, the adding amount of the active lime is 800 plus or minus 50 kg/furnace, and the adding amount of the furnace calcium series top slag modifier is 500 plus or minus 50 kg/furnace.
In the step b, the chemical composition P of the molten steel is controlled to be less than or equal to 0.013, S is controlled to be less than or equal to 0.003 and Als is controlled to be 0.025-0.040.
In the step b, the soft blowing time of argon is more than or equal to 8min, and the argon flow is based on that the molten steel is turned over and is not exposed.
In the step c, constant-speed pouring is adopted.
The invention has the beneficial effects that: the invention can reduce the inclusion content in the steel and improve the cleanliness of the steel by accurately controlling the components of the continuous annealing low alloy steel HC500LA and the modifier and matching with the smelting method. The invention adopts calcium carbide as a modifier reducing component, and a deoxidation product generated by the reaction of the calcium carbide and oxygen is gas (CO or CO)2) The molten steel cannot enter to form inclusions; meanwhile, the calcium carbide is easy to foam, submerged arc heating and air isolation are facilitated, and the secondary oxidation and nitrogen absorption degree is reduced; and thirdly, compared with deoxidation materials such as aluminum, the calcium carbide is lower in price and beneficial to cost control. Meanwhile, Al is added into the modifier2O3The method is beneficial to adjusting the components of the steel ladle slag to enable the steel ladle slag to be in a low melting point area, and can improve the adsorption capacity of inclusions and reduce the addition amount of steel slag fluorite.
The low superheat degree is beneficial to controlling the segregation of the casting blank, but the low superheat degree can lead to the solidification of cold steel or no pouring of the molten steel; the high degree of superheat is beneficial to floating removal of inclusions in the continuous casting process, but is unfavorable for casting blank segregation, so that the degree of superheat is controlled to be 20-35 ℃, and a better casting blank segregation effect can be achieved. The high-strength steel is easy to have longitudinal cracks at the corners of the casting blank, the proportion is about 1 percent, and therefore the yield of rolled products is low, the chamfer crystallizer is adopted in the continuous casting process, the longitudinal cracks at the corners of the casting blank can be reduced, and the longitudinal crack proportion at the corners of the casting blank can be reduced to be within 0.1 percent after the chamfer crystallizer is applied. Meanwhile, the invention also adopts soft reduction, controls the pulling speed to be 0.9-1.3m/min, can effectively improve the internal quality of the casting blank, and reduces the defects of segregation, porosity and the like.
The invention provides a group of continuous annealing low alloy steel HC500LA and a smelting method thereof, which can effectively improve the cleanliness of molten steel, reduce the longitudinal crack proportion of casting blank corners and improve the smelting yield of the continuous annealing low alloy steel HC500LA from less than 80% in the early stage to more than 95%.
Detailed Description
The technical solution of the present invention can be specifically implemented as follows.
The continuous annealing low alloy steel HC500LA comprises the following chemical components in percentage by mass: 0.06-0.08% of C, 0.12-0.18% of Si, 1.20-1.30% of Mn, less than or equal to 0.015% of P, less than or equal to 0.005% of S, 0.050-0.060% of Nb, 0.030-0.040% of Ti, 0.015-0.050% of Als, and the balance of Fe and inevitable impurities.
The smelting method of the continuous annealing low alloy steel HC500LA comprises the following steps:
a. a converter smelting process: controlling the converter to enter molten steel]Not more than 0.003 percent of the total content of the components, and the content of [ C ] in the molten steel at the end point of the converter]0.03-0.05 percent of steel tapping process, adding active lime in the steel tapping process, adding a calcium top slag modifier to the slag surface after the steel tapping process is finished, wherein the chemical component of the furnace calcium top slag modifier is CaC2 30-50％，Al2O3 10-30％，CaO 20-40％，CaF28-15%, S is less than or equal to 0.2, P is less than or equal to 0.1, and the balance is inevitable impurities;
and b, LF refining: controlling the chemical components of the molten steel to be 0.06-0.08 percent of C, 0.12-0.18 percent of Si, 1.20-1.30 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, 0.050-0.060 percent of Nb, 0.030-0.040 percent of Ti, 0.015-0.050 percent of Als and the balance of Fe and inevitable impurities, and carrying out soft blowing by adopting argon before the molten steel is discharged;
c. and (3) continuous casting process: controlling the superheat degree of the molten steel in the continuous casting tundish to be 20-35 ℃, adopting a chamfering crystallizer, applying soft reduction and pulling speed to be 0.9-1.3 m/min.
In order to reduce the desulfurization task of the LF refining process, reduce the nitrogen degree in the air sucked in the desulfurization refining process, simultaneously provide the production efficiency and shorten the desulfurization time, in the step a, the [ S ] in the molten steel fed into the converter is controlled to be less than or equal to 0.003 percent.
And (b) controlling the content of [ C ] in the molten steel at the end point of the converter to be 0.03-0.05% in the step a because the carbon requirement of a finished product is met, and the increase of the consumption of deoxidized alloy and the cost of the deoxidized alloy caused by the higher oxygen content in the steel due to the deep blowing of the converter is avoided, and the reduction of the cleanliness of the molten steel caused by the increase of deoxidized products is also avoided.
In the slag washing, in order to prevent the reduction of the rephosphorization degree due to resulfurization, it is preferable that the active lime is added in an amount of 800 + -50 kg/furnace in the step a; in order to reduce the oxidability of the ladle slag, prevent resulfurization and improve the adsorption effect of the steel slag on inclusions, it is preferable that the addition amount of the furnace calcium-based top slag modifier in the step a is 500 +/-50 kg/furnace. The addition of active lime and furnace calcium series top slag modifier can also play a role in heat preservation.
In order to more precisely control the chemical composition of the final steel material, it is preferable that the chemical composition P of molten steel is controlled to 0.013, S is controlled to 0.003, and Als is controlled to 0.025 to 0.040 in the above step b.
In order to remove the inclusions in the molten steel better, it is preferable that in the step b, the argon soft blowing time is not less than 8min, and the argon flow is based on that the molten steel is turned over and is not exposed.
For better control of the internal quality of the cast strand, it is therefore preferred that in step c, a constant rate of casting is used.
The technical solution and effects of the present invention will be further described below by way of practical examples.
Examples
The invention provides a group of embodiments for smelting continuous annealing low alloy steel HC500LA by adopting the method.
The semisteel after being extracted with water, vanadium and desulfurized contains, by weight, 3.41% of C, 0.041% of Mn, 0.062% of P, 0.002% of S, 0.04% of V, trace amounts of Cr, Si and Ti, and the balance of iron and inevitable impurities.
The specific smelting steps are as follows:
(1) 232.1 tons of the semi-steel are added into a top-bottom combined blowing converter with the capacity of 220 tons (nominal capacity), and the semi-steel is primarily smelted into molten steel by utilizing the function of oxygen blowing and decarburization of the top-bottom combined blowing converter. When the molten steel is initially refined to the temperature of 1671 ℃ and the C content is 0.038 wt%, the Mn content is 0.032 wt%, the P content is 0.0081 wt%, and the S content is 0.0041 wt%, tapping from the thick slag to a steel ladle;
(2) 820Kg of active lime is added in the tapping process, and 460Kg of calcium top slag modifier is added after tapping is finished;
(3) fine-adjusting alloy components in the LF process, wherein chemical components after fine adjustment are shown in table 1, soft blowing is carried out for 9min by adopting small argon flow before the LF molten steel is discharged, the molten steel is not exposed after being turned over in the soft blowing process, and the discharge temperature is controlled to be 1585 DEG C
TABLE 1 post-fine-tuning composition/% of LF alloy
| C | Si | Mn | P | S | Nb | Ti | Als |
| 0.065 | 0.15 | 1.25 | 0.011 | 0.001 | 0.052 | 0.035 | 0.036 |
(4) Controlling the superheat degree of the molten steel in the continuous casting to be 25 ℃, adopting a chamfering crystallizer, putting the molten steel under light pressure, and pulling at the speed of 1.1 m/min.
The chemical composition of the finished continuous annealing low alloy steel HC500LA is examined, and the chemical composition of the steel is shown in Table 2.
TABLE 2 Final ingredient/%)
| C | Si | Mn | P | S | Nb | Ti | Als |
| 0.07 | 0.15 | 1.25 | 0.011 | 0.001 | 0.051 | 0.032 | 0.031 |
The continuous annealing low alloy steel HC500LA prepared by the method has the yield strength of 500-550MPa, the tensile strength of more than or equal to 550MPa and the elongation of more than or equal to 16; the smelting rate of the continuous annealing low alloy steel HC500LA smelted by the method is improved to 98 percent from 88 percent in the early stage; after the method of the present invention is adopted, the T [ O ] of casting blank is reduced from 14-28ppm (average 23ppm) to 7-18ppm (average 13ppm), and the cleanliness of molten steel is obviously improved.
Claims (6)
1. The continuous annealing low alloy steel HC500LA is characterized in that the chemical components by mass percent are as follows: 0.06-0.08% of C, 0.12-0.18% of Si, 1.20-1.30% of Mn, less than or equal to 0.015% of P, less than or equal to 0.005% of S, 0.050-0.060% of Nb, 0.030-0.040% of Ti, 0.015-0.050% of Als, and the balance of Fe and inevitable impurities.
2. The method of smelting continuous annealing low alloy steel HC500LA, according to claim 1, comprising the steps of:
a. a converter smelting process: controlling the converter to enter molten steel]Not more than 0.003 percent of the total content of the components, and the content of [ C ] in the molten steel at the end point of the converter]0.03-0.05 percent of steel tapping process, adding active lime in the steel tapping process, adding a calcium top slag modifier to the slag surface after the steel tapping process is finished, wherein the chemical component of the furnace calcium top slag modifier is CaC2 30-50％，Al2O3 10-30％，CaO 20-40％，CaF28-15%, S is less than or equal to 0.2, P is less than or equal to 0.1, and the balance is inevitable impurities;
and b, LF refining: controlling the chemical components of the molten steel to be 0.06-0.08 percent of C, 0.12-0.18 percent of Si, 1.20-1.30 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, 0.050-0.060 percent of Nb, 0.030-0.040 percent of Ti, 0.015-0.050 percent of Als and the balance of Fe and inevitable impurities, and carrying out soft blowing by adopting argon before the molten steel is discharged;
c. and (3) continuous casting process: controlling the superheat degree of the molten steel in the continuous casting tundish to be 20-35 ℃, adopting a chamfering crystallizer, applying soft reduction and pulling speed to be 0.9-1.3 m/min.
3. The method for smelting continuous annealing low alloy steel HC500LA, according to claim 2, wherein: in the step a, the adding amount of the active lime is 800 plus or minus 50 kg/furnace, and the adding amount of the furnace calcium series top slag modifier is 500 plus or minus 50 kg/furnace.
4. The method for smelting continuous annealing low alloy steel HC500LA, according to claim 2, wherein: in the step b, the chemical composition P of the molten steel is controlled to be less than or equal to 0.013, S is controlled to be less than or equal to 0.003 and Als0.025-0.040.
5. The method for smelting continuous annealing low alloy steel HC500LA, according to claim 2, wherein: in the step b, the soft blowing time of argon is more than or equal to 8min, and the argon flow is based on that the molten steel is turned over and is not exposed.
6. The method for smelting continuous annealing low alloy steel HC500LA, according to claim 2, wherein: and c, adopting constant-speed pouring.
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