CN116254386A - Medium alloy electric furnace steel smelting method - Google Patents
Medium alloy electric furnace steel smelting method Download PDFInfo
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- CN116254386A CN116254386A CN202310128699.9A CN202310128699A CN116254386A CN 116254386 A CN116254386 A CN 116254386A CN 202310128699 A CN202310128699 A CN 202310128699A CN 116254386 A CN116254386 A CN 116254386A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 103
- 239000010959 steel Substances 0.000 title claims abstract description 103
- 238000000034 method Methods 0.000 title claims abstract description 78
- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 32
- 239000000956 alloy Substances 0.000 title claims abstract description 32
- 238000003723 Smelting Methods 0.000 title claims abstract description 31
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 117
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 88
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical group [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 79
- 229910052760 oxygen Inorganic materials 0.000 claims description 79
- 239000001301 oxygen Substances 0.000 claims description 79
- 229910052757 nitrogen Inorganic materials 0.000 claims description 59
- 238000007664 blowing Methods 0.000 claims description 58
- 229910052786 argon Inorganic materials 0.000 claims description 44
- 238000010079 rubber tapping Methods 0.000 claims description 28
- 238000005261 decarburization Methods 0.000 claims description 24
- 229910000851 Alloy steel Inorganic materials 0.000 claims description 23
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 22
- 229910052799 carbon Inorganic materials 0.000 claims description 16
- 239000002893 slag Substances 0.000 claims description 16
- 230000000694 effects Effects 0.000 claims description 15
- 230000002829 reductive effect Effects 0.000 claims description 15
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 12
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 12
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 12
- 239000010436 fluorite Substances 0.000 claims description 12
- 239000004571 lime Substances 0.000 claims description 12
- 238000005266 casting Methods 0.000 claims description 10
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 7
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 239000006260 foam Substances 0.000 claims description 6
- 238000007670 refining Methods 0.000 claims description 6
- 239000007789 gas Substances 0.000 claims description 4
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- 238000002844 melting Methods 0.000 claims description 4
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- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 4
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 4
- 238000003756 stirring Methods 0.000 claims description 4
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- 239000005997 Calcium carbide Substances 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 3
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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 claims description 3
- 238000009849 vacuum degassing Methods 0.000 description 19
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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
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/52—Manufacture of steel in electric furnaces
- C21C5/5229—Manufacture of steel in electric furnaces in a direct current [DC] electric arc furnace
-
- 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
-
- 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 application relates to the field of molten steel smelting, in particular to a medium alloy electric furnace steel smelting method, and discloses a medium alloy electric furnace steel smelting method.
Description
Technical Field
The application relates to the field of molten steel smelting, in particular to a smelting method of medium alloy electric furnace steel.
Background
The medium alloy steel refers to alloy steel with alloy content of 5-10%, mainly an electric furnace production flow is adopted, and most of the steel contains a large amount of nitrogen-philic elements such as Cr, mn and the like, and the nitrogen content is often more than 40 ppm. Medium alloy steel generally has the characteristics of high strength or high wear resistance, and excessively high nitrogen content has a plurality of effects on materials, such as increasing the aging of the steel, reducing the cold workability of the steel, causing cracking of the materials and causing intergranular corrosion, and generating carbonitrides with Nb, ti and the like in the steel, thereby influencing the service performance and service life of the materials.
The steel produced by the converter can obtain low-nitrogen steel with nitrogen less than 30ppm after the converter treatment due to high oxygen supply strength and large decarburization amount. However, the existing arc furnace is different from a converter, the oxygen supply intensity is smaller, the transient carbon-oxygen reaction is not as good as that of the converter, the arc furnace needs to be heated by an electrode, the denitrification effect is poor, and the single quantity of finished products is more than 40 ppm.
Against the background, a medium alloy electric furnace steel smelting method is needed, and the problems that the existing electric arc furnace has poor denitrification effect and the nitrogen content of the medium alloy steel is high when the alloy steel is smelted can be solved.
Disclosure of Invention
The purpose of the application is to provide a smelting method of medium alloy electric furnace steel, which can solve the problems that the existing electric arc furnace has poor denitrification effect and the nitrogen content of the medium alloy steel is higher when the alloy steel is smelted.
In order to achieve the above purpose, the embodiment of the present application adopts the following technical scheme: a smelting method of medium alloy electric furnace steel comprises the following steps: s1, tapping temperature T=1650-1675 ℃ of an electric furnace, and ending oxygen [ O ]]150-250 ppm, 0.25-0.35% of terminal carbon, and a little lime and fluorite are added in the tapping process to cover the slag surface; s2, VOD arrival temperature T=1600-1630 ℃, oxygen [ O ]]Oxygen blowing and decarbonizing under 100-200 ppm and vacuum degree of 1.5-2 KPa, bottom blowing argon and flow rate of 15-20 Nm 3 And/h, the pressure is 0.5-0.7 MPa; s3, the oxygen blowing amount is 3.5-4.0 Nm per ton of steel 3 End point carbon is 0.05-0.06%, argon is blown at bottom after oxygen blowing, flow is 20-30 Nm 3 And/h, carrying out clean vacuumizing for 5-8 minutes under the pressure of 0.5-0.7 MPa; s4, weakening the influence of nitrogen increase in the tapping process through VOD, generating a large number of carbon monoxide bubbles in the molten steel in the VOD decarburization process, denitrifying the molten steel, wherein each bubble is an independent vacuum unit, and reducing part of surface active elements is convenient for further denitrification in the subsequent steps;s5, LF refining, wherein the argon flow in the early slag melting stage is 15-25 Nm 3 Carrying out slag-top deoxidation and foam slag submerged arc on carbon powder, silicon carbide and calcium carbide by using current 20KA, and forming foam slag and then carrying out argon flow of 10-13 Nm 3 And/h, the current is 30-35 KA; s6, measuring the temperature at the LF station to be greater than or equal to 1620 ℃ and adding alloy in batches, wherein the argon flow is 15-25 Nm 3 And/h, the current is 30-35 KA; s7, the LF tapping temperature is higher than or equal to 1640 ℃, the argon flow is regulated before tapping, so that the liquid level of the steel is not exposed, and the argon pressure is lower than or equal to 0.3MPa; s8, opening bottom argon blowing after vacuum pumping to high vacuum, and adopting a large stirring mode, wherein the high vacuum holding time is more than or equal to 15 minutes, so as to further denitrify; s9, adopting casting protection to ensure that the nitrogen increment in the casting process is not more than 2ppm.
Further, according to the embodiment of the application, 1.5-2.5 kg of lime ton steel in S1 and 0.6kg of fluorite ton steel are adopted.
Further, according to the embodiment of the application, the S2 oxygen flow is 1000-1200 Nm 3 And/h, oxygen pressure is 0.8-1.0 MPa.
Further, according to the embodiment of the application, 10-15 kg of lime ton steel and 5kg of fluorite ton steel are firstly mixed in S5.
Further, according to the embodiment of the application, in the step S6, no arc light is required to be exposed, the sealing effect of the furnace cover is ensured, and nitrogen increase in the process is reduced.
Further, according to the embodiment of the present application, the bottom blowing flow rate in S8 may be 15 to 25Nm 3 /h。
Further, according to an embodiment of the present application, the protective gas pressure in S9 is 0.3 to 0.6MPa.
Further, according to the embodiment of the present application, the nitrogen content of the medium alloy steel can be 30ppm or less.
Compared with the prior art, the application has the following beneficial effects:
the application adopts a medium alloy electric furnace steel smelting method and adopts an electric arc furnace and VOD duplex technology. When the electric arc furnace is finished, VOD (vacuum oxygen blowing decarburization) is carried out, nitrogen increasing influence in the tapping process is weakened through VOD, a large number of carbon monoxide bubbles can be generated in molten steel in the VOD decarburization process, the molten steel is denitrified, each bubble is an independent vacuum unit, partial surface active elements are reduced, further denitrification is facilitated in subsequent steps, the VOD vacuum decarburization denitrification process is added, the nitrogen content in the molten steel before nitrogen fixation elements are greatly added is guaranteed to reach low content, the problems that the existing electric arc furnace is poor in denitrification effect when alloy steel is smelted and the nitrogen content of medium alloy steel is high are solved, the denitrification effect when the medium alloy steel is smelted is improved, and the effect of reducing the nitrogen content of the medium alloy steel is achieved.
Drawings
The present application is further described below with reference to the drawings and examples.
FIG. 1 is a schematic flow chart of a method for smelting medium alloy electric furnace steel in an embodiment.
Detailed Description
In order to make the objects, technical solutions, and advantages of the present invention more apparent, the embodiments of the present invention will be further described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are some, but not all, embodiments of the present invention, are intended to be illustrative only and not limiting of the embodiments of the present invention, and that all other embodiments obtained by persons of ordinary skill in the art without making any inventive effort are within the scope of the present invention.
In the description of the present invention, it should be noted that the terms "center," "middle," "upper," "lower," "left," "right," "inner," "outer," "top," "bottom," "side," "vertical," "horizontal," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate description of the present invention and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "a," an, "" the first, "" the second, "" the third, "" the fourth, "" the fifth, "and the sixth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
For purposes of brevity and description, the principles of the embodiments are described primarily by reference to examples. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent, however, to one of ordinary skill in the art that the embodiments may be practiced without limitation to these specific details. In some instances, well-known methods and structures have not been described in detail so as not to unnecessarily obscure the embodiments. In addition, all embodiments may be used in combination with each other.
According to the smelting method of the medium alloy electric furnace steel, dephosphorization and VOD (vacuum oxygen blowing decarburization) are carried out by adopting an electric furnace, decarburization and denitrification are carried out by adopting a ladle refining furnace (LF) to carry out deoxidization alloying and VD (vacuum degassing) to carry out degassing and protection pouring process production, so that the effects of improving the purity of the alloy steel, improving the benefit, reducing unstable factors in the production process and shortening the smelting time are achieved.
Embodiment one:
as shown in fig. 1, the application discloses a smelting method of medium alloy electric furnace steel, comprising the following steps:
s1, the tapping temperature T=1650-1675 ℃ of an electric furnace, the terminal oxygen [ O ] is 150-250 ppm, the terminal carbon is 0.25-0.35%, and a little lime and fluorite are added in the tapping process to cover the slag surface;
s2, VOD arrival temperature T=1600-1630 ℃, oxygen [ O ]]Oxygen blowing and decarbonizing under 100-200 ppm and vacuum degree of 1.5-2 KPa, bottom blowing argon and flow rate of 15-20 Nm 3 Pressure/h0.5～0.7MPa；
S3, the oxygen blowing amount is 3.5-4.0 Nm per ton of steel 3 End point carbon is 0.05-0.06%, argon is blown at bottom after oxygen blowing, flow is 20-30 Nm 3 And/h, carrying out clean vacuumizing for 5-8 minutes under the pressure of 0.5-0.7 MPa;
s4, weakening the influence of nitrogen increase in the tapping process through VOD, generating a large number of carbon monoxide bubbles in the molten steel in the VOD decarburization process, denitrifying the molten steel, wherein each bubble is an independent vacuum unit, and reducing part of surface active elements is convenient for further denitrification in the subsequent steps;
s5, LF refining, wherein the argon flow in the early slag melting stage is 15-25 Nm 3 Carrying out slag-top deoxidation and foam slag submerged arc on carbon powder, silicon carbide and calcium carbide by using current 20KA, and forming foam slag and then carrying out argon flow of 10-13 Nm 3 And/h, the current is 30-35 KA;
s6, measuring the temperature at the LF station to be greater than or equal to 1620 ℃ and adding alloy in batches, wherein the argon flow is 15-25 Nm 3 And/h, the current is 30-35 KA;
s7, the LF tapping temperature is higher than or equal to 1640 ℃, the argon flow is regulated before tapping, so that the liquid level of the steel is not exposed, and the argon pressure is lower than or equal to 0.3MPa;
s8, opening bottom argon blowing after vacuum pumping to high vacuum, and adopting a large stirring mode, wherein the high vacuum holding time is more than or equal to 15 minutes, so as to further denitrify;
s9, adopting casting protection to ensure that the nitrogen increment in the casting process is not more than 2ppm.
Specifically, 1.5-2.5 kg of lime ton steel in the S1 and 0.6kg of fluorite ton steel.
Specifically, the oxygen flow rate of the S2 is 1000-1200 Nm 3 And/h, oxygen pressure is 0.8-1.0 MPa.
Specifically, after the oxygen blowing is finished, the S3 is subjected to clean vacuumizing, the vacuum degree is slowly reduced, and the vacuum degree is smaller than 200pa after 5-8 minutes.
Specifically, 10-15 kg of lime ton steel and 5kg of fluorite ton steel are firstly mixed in the S5.
Specifically, in the step S6, arc light is not exposed, the sealing effect of the furnace cover is ensured, and nitrogen increase in the process is reduced.
Specifically, in S8, the bottom blowing flow rate can be referred to 15-25 Nm 3 /h。
Specifically, the pressure of the protective gas in the step S9 is 0.3-0.6 MPa.
Specifically, the nitrogen content of the medium alloy steel obtained by the method can be less than or equal to 30ppm.
In the conventional method, in the general case, a great deal of nitrogen increasing in the processes of an Electric Arc Furnace (EAF) and a converter (LD) occurs in the tapping process of the roughing furnace (EAF and LD), a great deal of alloy is added in the tapping process, and nitrogen-philic elements such as Cr and Mn are contained in the alloy to cause difficult nitrogen removal in the VD process, so that the nitrogen content in molten steel cannot be reduced to be particularly low.
The invention weakens the nitrogen increasing effect in the tapping process of the rough smelting furnace through an EAF+VOD duplex process. In the VOD decarburization process, a large number of CO (carbon monoxide) bubbles are generated in molten steel, each bubble is an independent vacuum unit, and the nitrogen element in the molten steel is separated conveniently through the reaction of a large number of CO and the nitrogen element in the molten steel, so that the intensity of denitrification is stronger than that in the denitrification process of EAF and LD.
The CO partial pressure in the environment in the VOD process is low, the oxygen content in the molten steel of the coarse steel subjected to VOD decarburization can be reduced to a very low level, generally less than 200ppm, the deoxidization pressure in LF is reduced, and the desulfurization effect in LF is better; the content of surface active elements such as O (oxygen), S (sulfur) and the like in the molten steel is reduced through VOD, so that the molten steel is convenient to further denitrate in the VD process, and the denitrogenation effect is better.
The comparison table of the elements such as nitrogen and the like of the steel manufactured by the prior method and the invention is as follows:
| existing technologyOperation 1 | PRIOR ART 2 | The application | |
| Smelting method | Electric arc furnace +LF +VD | converter+LF+VD | Electric arc furnace +VOD +LF +VD |
| Nitrogen content/ppm | 40～65 | 40～70 | ≤30 |
According to the smelting method of the medium alloy electric furnace steel, the coarse steel with low nitrogen content is obtained through the electric arc furnace and the VOD, nitrogen is prevented from increasing in the subsequent smelting process, VD final denitrification is carried out on molten steel under the condition of very good deoxidation, clean molten steel with the nitrogen content of less than or equal to 30ppm can be stably obtained through the method, and the method can be applied to medium manganese steel and high-chromium steel, such as hot work die steel, high-strength medium manganese steel and the like.
The invention is applicable to various steels, the foundation of the invention is LF submerged arc technology and protection casting technology, and the invention is decisive technology for preventing nitrogen increase in LF and casting processes. The method increases the VOD vacuum decarburization denitrification process, and ensures that the nitrogen content in the molten steel reaches low content before adding a large amount of nitrogen fixation elements.
Embodiment two:
taking 4Cr5MoSiV1 (alloy steel) as an example, the smelting method of the medium alloy electric furnace steel adopts an electric furnace to carry out dephosphorization, VOD (vacuum oxygen blowing decarburization) to carry out decarburization, denitrification, LF (ladle refining furnace) to carry out deoxidization alloying, VD (vacuum degassing) to carry out degassing and protection casting process production, thereby achieving the effects of improving the purity of the alloy steel, improving the benefit, reducing unstable factors in the production process and shortening the smelting time, and the specific process is as follows:
s10, the tapping temperature T=1650-1675 ℃ of the electric furnace, the terminal oxygen [0] is 150-250 ppm, the terminal carbon is 0.32%, the key phosphorus is 0.006%, the tapping amount is 50T, a little lime and fluorite are added in the tapping process to cover the slag surface, the lime ton steel is 100kg, and the fluorite ton steel is 30kg.
S20, VOD arrival temperature t=1615 ℃, oxygen [0]]150ppm, starting at a vacuum of 2KPa, an oxygen flow of 1000Nm 3 And/h, the oxygen pressure is 0.99MPa, and the bottom blowing argon flow is 20Nm 3 And/h, the pressure is 0.7MPa.
S30, oxygen blowing amount is 200Nm per ton of steel 3 The flow of bottom argon blowing after oxygen blowing is 25Nm 3 And/h, the pressure is 0.7MPa, then the vacuum is performed for 6 minutes, and the endpoint carbon is 0.06%.
S40, weakening the influence of nitrogen increase in the tapping process through VOD, generating a large number of carbon monoxide bubbles in the molten steel in the VOD decarburization process, denitrifying the molten steel, wherein each bubble is an independent vacuum unit, and reducing part of surface active elements is convenient for further denitrification in subsequent steps.
S50, LF refining, adding 750kg of lime ton steel and 200kg of fluorite ton steel, wherein the argon flow is 15-25 Nm in the early slag melting stage 3 And/h, the current is 20KA, the carbon powder is 30kg, the silicon carbide is 30kg, then the slag is deoxidized and foamed submerged arc is carried out, and the flow of argon is 10Nm after the foamed slag is formed 3 And/h, current 35 KA.
S60, measuring the temperature at the LF station to be 1640 ℃, then starting to supplement alloy in batches, wherein about 800kg of alloy is added each time, the total of about 3300kg is obtained after 4 times of addition, and the argon flow is 22Nm 3 And/h, the current is 35KA, arc light is not leaked in the process, the furnace cover covers the ladle opening, and the furnace door is closed in the process of adding alloy.
S70, the tapping temperature of LF is 1670 ℃, and the argon flow is regulated before tapping to ensure that the liquid surface of steel is not exposed, and the argon pressure is 0.2MPa.
And S80, vacuumizing to 130Pa in the VD, starting bottom blowing argon, adopting a large stirring mode, wherein the flow rate of bottom blowing is 25Nm3/h, the high vacuum holding time is more than or equal to 15 minutes, further performing denitrification, and the nitrogen content after VD is 22ppm.
S90, adopting casting protection, wherein the pressure of the protective gas is 0.5MPa, so that the nitrogen content of the finished product is 23ppm, and the nitrogen is increased by about 1ppm in the process.
In the conventional method, in the general case, a great deal of nitrogen increasing in the processes of an Electric Arc Furnace (EAF) and a converter (LD) occurs in the tapping process of the roughing furnace (EAF and LD), a great deal of alloy is added in the tapping process, and nitrogen-philic elements such as Cr and Mn are contained in the alloy to cause difficult nitrogen removal in the VD process, so that the nitrogen content in molten steel cannot be reduced to be particularly low.
The nitrogen content of the steel produced by comparing the prior art method with the present application is as follows:
| prior Art 1 | PRIOR ART 2 | The application | |
| Smelting method | Electric arc furnace +LF +VD | converter+LF+VD | Electric arc furnace +VOD +LF +VD |
| Nitrogen content/ppm | 40～65 | 40～70 | 23 |
In summary, the invention has the following beneficial effects: 1. the purity is improved: VOD draws carbon, and terminal carbon control is accurate, and the molten steel does not have the peroxidation condition, and deoxidization process inclusion is few. 2. The benefit is high: the nitrogen of the finished product can be stabilized by about 23ppm, and the unstable factors in the production process are reduced. 3. The LF and VD pressure is reduced through VOD decarburization and denitrification, the smelting time is shortened, and the molten steel smelting time is shortened.
Embodiment III:
in this example, for example, 4Cr5MoSiV1 (alloy steel), VOD arrival temperature t=1610 ℃, oxygen [0]]Oxygen decarburization by blowing oxygen at 150ppm and vacuum level 2KPa, oxygen flow 1050Nm 3 And/h, the oxygen pressure is 0.99MPa, and the bottom blowing argon flow is 20Nm 3 And/h, the pressure is 0.7MPa.
Oxygen blowing amount was 200Nm per ton of steel 3 Bottom blowing argon flow 25Nm after oxygen blowing 3 And/h, the pressure is 0.7MPa, then the vacuum is cleaned for 6 minutes, and the end point carbon is 0.06%.
Molten steel having a nitrogen content of 24ppm was obtained by this example.
Embodiment four:
in this example, for example, 4Cr5MoSiV1 (alloy steel), VOD arrival temperature t=1605 ℃, oxygen [0]]Oxygen decarburization by blowing oxygen at 125ppm and vacuum of 1.7KPa, oxygen flow rate of 1100Nm 3 And/h, the oxygen pressure is 0.99MPa, and the bottom blowing argon flow is 17Nm 3 And/h, the pressure is 0.6MPa.
Oxygen blowing amount was 200Nm per ton of steel 3 Bottom blowing argon flow 22Nm after oxygen blowing 3 And/h, the pressure is 0.6MPa, then the vacuum is cleaned for 6 minutes, and the endpoint carbon is 0.06%.
Molten steel having a nitrogen content of 25ppm was obtained by this example.
Fifth embodiment:
in this example, taking 4Cr5MoSiV1 (alloy steel) as an example, VOD arrival temperature t=1600 ℃, oxygen [ O ]]Oxygen decarburization by blowing oxygen at 100ppm and vacuum degree of 1.5KPa, oxygen flow rate of 1200Nm 3 And/h, the oxygen pressure is 0.99MPa, and the bottom blowing argon flow is 15Nm 3 And/h, the pressure is 0.5MPa.
Oxygen blowing amount was 200Nm per ton of steel 3 Bottom argon blowing flow 20Nm after oxygen blowing 3 And/h, the pressure is 0.5MPa, then the vacuum is cleaned for 6 minutes, and the endpoint carbon is 0.06%.
Molten steel having a nitrogen content of 26ppm was obtained by this example.
Example six:
in this example, taking 4Cr5MoSiV1 (alloy steel) as an example, VOD arrival temperature t=1620 ℃ and oxygen [ O ]]Oxygen decarburization by blowing oxygen at 150ppm and vacuum degree of 2KPa, oxygen flow rate of 1000Nm 3 And/h, the oxygen pressure is 0.99MPa, and the bottom blowing argon flow is 20Nm 3 And/h, the pressure is 0.7MPa.
Oxygen blowing amount was 200Nm per ton of steel 3 Bottom blowing argon flow 25Nm after oxygen blowing 3 And/h, the pressure is 0.7MPa, then the vacuum is cleaned for 6 minutes, and the end point carbon is 0.06%.
Molten steel having a nitrogen content of 24ppm was obtained by this example.
Embodiment seven:
in this example, taking 4Cr5MoSiV1 (alloy steel) as an example, VOD arrival temperature t=1625 ℃, oxygen [ O ]]Oxygen decarburization by blowing oxygen at 175ppm and vacuum of 1.7KPa, oxygen flow of 1100Nm 3 And/h, the oxygen pressure is 0.99MPa, and the bottom blowing argon flow is 17Nm 3 And/h, the pressure is 0.6MPa.
Oxygen blowing amount was 200Nm per ton of steel 3 Bottom argon blowing flow 27Nm after oxygen blowing 3 And/h, the pressure is 0.6MPa, then the vacuum is cleaned for 6 minutes, and the endpoint carbon is 0.06%.
Molten steel having a nitrogen content of 25ppm was obtained by this example.
Example eight:
in this example, taking 4Cr5MoSiV1 (alloy steel) as an example, VOD arrival temperature t=1630 ℃, oxygen [ O ]]Oxygen decarburization by blowing oxygen at 200ppm and vacuum degree of 1.5KPa, oxygen flow rate of 1200Nm 3 And/h, the oxygen pressure is 0.99MPa, and the bottom blowing argon flow is 15Nm 3 And/h, the pressure is 0.5MPa.
Oxygen blowing amount was 200Nm per ton of steel 3 Bottom argon blowing flow 30Nm after oxygen blowing 3 And/h, the pressure is 0.5MPa, then the vacuum is cleaned for 6 minutes, and the endpoint carbon is 0.06%.
Molten steel having a nitrogen content of 26ppm was obtained by this example.
The experimental conditions for examples two to eight are summarized in the following table:
the nitrogen content of the prior art method is compared with that of each step of the invention:
| converter | Electric arc furnace | VOD | LF | VD | Pouring | |
| Example two | / | 70ppm | 35ppm | 40ppm | 23ppm | 23ppm |
| Comparative example one | / | 70ppm | / | 70ppm | 40ppm | 40ppm |
| Comparative example two | 65ppm | / | / | 65ppm | 35ppm | 35ppm |
As can be seen from the table, the nitrogen increasing effect in the tapping process of the rough smelting furnace is weakened through the arc furnace and VOD duplex process. In the VOD decarburization process, a large number of CO (carbon monoxide) bubbles are generated in molten steel, each bubble is an independent vacuum unit, nitrogen elements in the molten steel are conveniently separated through a large number of CO, and the denitrification strength is stronger than that of a process of an electric arc furnace and a converter alone.
The CO partial pressure in the environment is low in the VOD process, and the oxygen content in the molten steel of the coarse steel subjected to VOD decarburization can be reduced to a very low level, generally less than 200ppm, so that the deoxidizing pressure in LF is reduced, and the desulfurizing effect in LF is better; the content of surface active elements such as O (oxygen), S (sulfur) and the like in the molten steel is reduced, so that the molten steel is convenient to further denitrogenate in the VD process, the denitrogenation effect is better, the nitrogen content in the molten steel reaches low content before adding a large amount of nitrogen fixation elements, and the clean molten steel with the nitrogen content less than or equal to 30ppm can be stably obtained.
While the foregoing has been described in terms of illustrative embodiments thereof, so that those skilled in the art may appreciate the present application, it is not intended to be limited to the precise embodiments so that others skilled in the art may readily utilize the present application to its various modifications and variations which are within the spirit and scope of the present application as defined and determined by the appended claims.
Claims (8)
1. A smelting method of medium alloy electric furnace steel comprises the following steps:
s1, the tapping temperature T=1650-1675 ℃ of an electric furnace, the terminal oxygen [ O ] is 150-250 ppm, the terminal carbon is 0.25-0.35%, and a little lime and fluorite are added in the tapping process to cover the slag surface;
s2, VOD arrival temperature T=1600-1630 ℃, oxygen [ O ]]Oxygen blowing and decarbonizing under 100-200 ppm and vacuum degree of 1.5-2 KPa, bottom blowing argon and flow rate of 15-20 Nm 3 And/h, the pressure is 0.5-0.7 MPa;
s3, the oxygen blowing amount is 3.5-4.0 Nm per ton of steel 3 End point carbon is 0.05-0.06%, argon is blown at bottom after oxygen blowing, flow is 20-30 Nm 3 And/h, carrying out clean vacuumizing for 5-8 minutes under the pressure of 0.5-0.7 MPa;
s4, weakening the influence of nitrogen increase in the tapping process through VOD, generating a large number of carbon monoxide bubbles in the molten steel in the VOD decarburization process, denitrifying the molten steel, wherein each bubble is an independent vacuum unit, and reducing part of surface active elements is convenient for further denitrification in the subsequent steps;
s5, LF refining, wherein the argon flow in the early slag melting stage is 15-25 Nm 3 Carrying out slag-top deoxidation and foam slag submerged arc on carbon powder, silicon carbide and calcium carbide by using current 20KA, and forming foam slag and then carrying out argon flow of 10-13 Nm 3 And/h, the current is 30-35 KA;
s6, measuring the temperature at the LF station to be greater than or equal to 1620 ℃ and adding alloy in batches, wherein the argon flow is 15-25 Nm 3 And/h, the current is 30-35 KA;
s7, the LF tapping temperature is higher than or equal to 1640 ℃, the argon flow is regulated before tapping, so that the liquid level of the steel is not exposed, and the argon pressure is lower than or equal to 0.3MPa;
s8, opening bottom argon blowing after vacuum pumping to high vacuum, and adopting a large stirring mode, wherein the high vacuum holding time is more than or equal to 15 minutes, so as to further denitrify;
s9, adopting casting protection to ensure that the nitrogen increment in the casting process is not more than 2ppm.
2. The method for smelting medium alloy electric furnace steel according to claim 1, wherein 1.5-2.5 kg of lime ton steel in the step S1 and 0.6kg of fluorite ton steel are adopted.
3. A method for smelting medium alloy electric furnace steel according to claim 1, wherein the S2 oxygen flow is 1000-1200 Nm 3 And/h, oxygen pressure is 0.8-1.0 MPa.
4. The method for smelting medium alloy electric furnace steel according to claim 1, wherein 10-15 kg of lime ton steel and 5kg of fluorite ton steel are firstly mixed in the step S5.
5. The method for smelting medium alloy electric furnace steel according to claim 1, wherein the arc light is not exposed in the step S6, the furnace cover sealing effect is ensured, and nitrogen increase in the process is reduced.
6. A method for producing medium alloy electric furnace steel according to claim 1, wherein the bottom blowing flow is 15-25 Nm in the step S8 3 /h。
7. The method for smelting medium alloy electric furnace steel according to claim 1, wherein the pressure of the protective gas in the S9 is 0.3-0.6 MPa.
8. The method according to any one of claims 1-7, wherein: the nitrogen content of the medium alloy steel obtained by the method can be less than or equal to 30ppm.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0770630A (en) * | 1993-09-03 | 1995-03-14 | Godo Seitetsu Kk | Smelting method for low-nitrogen steel by using electric furnace molten steel |
| CN1556227A (en) * | 2004-01-08 | 2004-12-22 | 太原钢铁(集团)有限公司 | Vacuum oxygen blowing decarbon refining furnace smelting stainless steel high carbon region denitrogen method |
| US20090019968A1 (en) * | 2006-02-09 | 2009-01-22 | Jfe Steel Corporation | Removal Method of Nitrogen in Molten Steel |
| CN102071287A (en) * | 2010-12-20 | 2011-05-25 | 攀钢集团钢铁钒钛股份有限公司 | Method for melting high-temperature-resistance and high-pressure-resistance alloy steel |
| JP2013072106A (en) * | 2011-09-27 | 2013-04-22 | Nippon Yakin Kogyo Co Ltd | Method for producing boron-containing stainless steel |
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2023
- 2023-02-17 CN CN202310128699.9A patent/CN116254386A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0770630A (en) * | 1993-09-03 | 1995-03-14 | Godo Seitetsu Kk | Smelting method for low-nitrogen steel by using electric furnace molten steel |
| CN1556227A (en) * | 2004-01-08 | 2004-12-22 | 太原钢铁(集团)有限公司 | Vacuum oxygen blowing decarbon refining furnace smelting stainless steel high carbon region denitrogen method |
| US20090019968A1 (en) * | 2006-02-09 | 2009-01-22 | Jfe Steel Corporation | Removal Method of Nitrogen in Molten Steel |
| CN102071287A (en) * | 2010-12-20 | 2011-05-25 | 攀钢集团钢铁钒钛股份有限公司 | Method for melting high-temperature-resistance and high-pressure-resistance alloy steel |
| JP2013072106A (en) * | 2011-09-27 | 2013-04-22 | Nippon Yakin Kogyo Co Ltd | Method for producing boron-containing stainless steel |
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