CN117987621B - RH single-linkage medium plate smelting method - Google Patents
RH single-linkage medium plate smelting method Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 83
- 238000003723 Smelting Methods 0.000 title claims abstract description 72
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 75
- 239000010959 steel Substances 0.000 claims abstract description 75
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 50
- 239000002893 slag Substances 0.000 claims abstract description 42
- 238000006477 desulfuration reaction Methods 0.000 claims abstract description 37
- 230000023556 desulfurization Effects 0.000 claims abstract description 37
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 32
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 32
- 239000011593 sulfur Substances 0.000 claims abstract description 32
- 229910052742 iron Inorganic materials 0.000 claims abstract description 25
- 238000009749 continuous casting Methods 0.000 claims abstract description 23
- 238000010079 rubber tapping Methods 0.000 claims abstract description 23
- 238000005275 alloying Methods 0.000 claims abstract description 21
- 238000005266 casting Methods 0.000 claims abstract description 16
- 238000009835 boiling Methods 0.000 claims abstract description 5
- 230000008569 process Effects 0.000 claims description 48
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 37
- 229910052760 oxygen Inorganic materials 0.000 claims description 37
- 239000001301 oxygen Substances 0.000 claims description 37
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 24
- 229910052799 carbon Inorganic materials 0.000 claims description 24
- 229910052782 aluminium Inorganic materials 0.000 claims description 15
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 15
- 238000007664 blowing Methods 0.000 claims description 10
- 239000003607 modifier Substances 0.000 claims description 8
- 239000003795 chemical substances by application Substances 0.000 claims description 7
- 230000003009 desulfurizing effect Effects 0.000 claims description 7
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 6
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 6
- 239000004571 lime Substances 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 abstract description 21
- 238000005265 energy consumption Methods 0.000 abstract description 12
- 239000000047 product Substances 0.000 description 34
- 238000007670 refining Methods 0.000 description 15
- 229910052791 calcium Inorganic materials 0.000 description 9
- 239000011575 calcium Substances 0.000 description 9
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 6
- 230000003749 cleanliness Effects 0.000 description 5
- 238000009489 vacuum treatment Methods 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 230000005611 electricity Effects 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- CQBLUJRVOKGWCF-UHFFFAOYSA-N [O].[AlH3] Chemical compound [O].[AlH3] CQBLUJRVOKGWCF-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000005261 decarburization Methods 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 238000010923 batch production Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
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- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000009847 ladle furnace Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
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- 238000002360 preparation method Methods 0.000 description 1
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- 239000000126 substance Substances 0.000 description 1
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Abstract
The invention relates to a smelting method of an RH single-linkage medium plate, which comprises the following steps of S1: KR desulfurization is carried out, the molten iron is desulfurized, slag skimming is carried out on the molten iron after desulfurization is finished, standing is carried out for 3-5min, and secondary slag skimming is carried out until no desulfurization slag exists on the surface of the molten iron, wherein the sulfur content in the molten iron after desulfurization is finished is less than or equal to 0.0010%; step S2: converter smelting, namely carrying out converter smelting on the molten steel subjected to desulfurization treatment in the step S1; step S3: RH treatment, namely, directly carrying out RH treatment on the converter molten steel obtained in the step S2 after boiling tapping, wherein the RH treatment lasts for 7-10min, alloying is carried out according to preset target components, and after alloying is completed, the net circulation lasts for 10-12min, and RH breaks the blank tapping; step S4: and (3) continuous casting, namely continuous casting is carried out on the molten steel obtained in the step (S3) to obtain a casting blank. The invention realizes high-efficiency low-energy-consumption medium plate smelting stable production, reduces the quantity of one-time deoxidization products and improves the control level of inclusions.
Description
Technical Field
The invention relates to a smelting method of an RH single-unit medium plate, and belongs to the technical field of steel preparation.
Background
The medium plate is an important metal material, mainly refers to a steel plate with the thickness of 4.5-25.0mm, plays a vital role in industrial production, and is widely applied to the fields of shipbuilding and ocean platforms, mechanical manufacturing, bridge manufacturing, transportation, electric power engineering and the like. Annual output of medium plates plays an important role in the whole steel manufacturing industry.
However, the existing smelting process of the medium-thickness plate has the problems of higher energy consumption and insufficient inclusion control level, and in order to solve the problems, some measures are needed to reduce the energy consumption and improve the inclusion control level. Patent CN115558834a discloses a medium plate steel grade and its smelting method, its technological process is molten iron pretreatment-converter smelting-LF refining-VD vacuum-continuous casting, through LF refining and VD vacuum treatment, the stable control of medium plate inclusion is implemented, and the adoption of calcium treatment process makes large-size inclusion be controlled below 10 μm, so that it solves the problem of that VD vacuum refining can not implement batch production. Patent CN102732666A discloses a method for controlling nonmetallic inclusions of a medium plate of hydrogen induced cracking resistant pipeline steel, which has the process route of converter smelting-ladle furnace refining-RH vacuum treatment-calcium treatment-soft blowing and calm-continuous casting, and meets the requirements of nonmetallic inclusions through the whole-process fine control of steelmaking, and the grades of various inclusions are below 0.5 level, so that the batch and stable production of the hydrogen induced cracking resistant pipeline steel is realized. Patent CN102864378B discloses a smelting process of a thick slab in X70 pipeline steel, which comprises the steps of molten iron pretreatment-converter smelting-LF refining-continuous casting, and realizes the mass production of low-cost pipeline steel by the calcium treatment technology after LF treatment and the inclusion floating up.
According to the prior art, the smelting process flow of the medium plate mainly comprises KR desulfurization, converter smelting, LF refining, (RH refining/VD treatment) and continuous casting. However, under the current industry requirements of carbon emission reduction and high quality, the following main problems exist in the process flow: 1) The process flow is long, the molten steel is long in package time, the temperature loss is large, and the power consumption is large; 2) The primary deoxidization products are more, and are difficult to effectively remove; 3) The calcium treatment operation is adopted, so that the cost is increased, the environment is polluted, and the cleanliness of molten steel is deteriorated.
As for patent CN106011595A, it discloses a smelting method for producing medium-thickness plate by adopting RH single-connection process, its technological process is molten iron pretreatment-converter smelting-RH vacuum-calcium treatment-continuous casting, and it mainly uses the method of controlling hydrogen element content in molten steel, and utilizes the strong deoxidation of converter tapping and calcium treatment to implement control of flaw detection qualification rate of said steel grade so as to meet the requirements of industrialization. However, after the calcium treatment operation is added, no solution is proposed for the problems of improving the cleanliness of the molten steel, reducing the smelting energy consumption and the like, which results in the increase of cost and environmental pollution and worsens the cleanliness of the molten steel.
Therefore, it is necessary to design a smelting method for the medium plate, which effectively improves the problems by optimizing the process, improving the energy utilization rate and enhancing the quality control, and promotes the development of the medium plate industry.
Disclosure of Invention
The invention provides a smelting method of an RH single-linked medium plate, which realizes high-efficiency and low-energy-consumption medium plate smelting stable production, reduces the number of one-time deoxidization products and improves the control level of inclusions.
The technical scheme adopted for solving the technical problems is as follows:
the RH single-joint medium plate smelting method aims at a medium plate with the thickness of 4.5-25mm and the width of more than or equal to 1500mm of a finished product, and specifically comprises the following steps:
Step S1: KR desulfurization is carried out, the molten iron is desulfurized, slag skimming is carried out on the molten iron after desulfurization is finished, standing is carried out for 3-5min, and secondary slag skimming is carried out until no desulfurization slag exists on the surface of the molten iron, wherein the sulfur content in the molten iron after desulfurization is finished is less than or equal to 0.0010%;
step S2: converter smelting, namely carrying out converter smelting on the molten steel subjected to desulfurization treatment in the step S1;
Step S3: RH treatment, namely, directly carrying out RH treatment on the converter molten steel obtained in the step S2 after boiling tapping, wherein the RH treatment lasts for 7-10min, alloying is carried out according to preset target components, and after alloying is completed, the net circulation lasts for 10-12min, and RH breaks the blank tapping;
After molten steel starts to circulate in a vacuum chamber, oxygen is blown in through an oxygen gun, the oxygen blowing amount is (emptying temperature-arrival temperature +22+a) multiplied by 6.7m 3, the aluminum adding amount is (emptying temperature-arrival temperature +22+a) multiplied by 7.5kg, wherein a depends on the carbon content of a finished product, the carbon content of the finished product is less than 0.06%, the value of a is 10, the carbon content of the finished product is more than or equal to 0.06% and less than 0.1%, the value of a is 20, and when the carbon content of the finished product is more than or equal to 0.1%, the value of a is 25;
step S4: continuous casting is carried out on the molten steel obtained in the step S3, and a casting blank is obtained;
As a further preferable mode of the invention, in the step S2, when the converter is used for smelting, the scrap steel ratio is 10-15%, and the sulfur content in the scrap steel is less than or equal to 0.005%;
the alkalinity of final slag at the end of converting is 3.0-3.5, the carbon content at the end of the converter is 0.04-0.06%, the free oxygen at the end is 0.04-0.06%, the temperature at the end is 1640-1660 ℃, and the sulfur content at the end of the converter is less than or equal to 0.003%;
As a further preferable mode of the invention, in the step S2, 2-3kg/t lime is added in the transferring process of molten steel from a converter to a ladle when the converter is tapped, and 1-2kg/t steel aluminum-based slag modifier is added on the surface of the molten steel after tapping is finished;
As a further preferred aspect of the present invention, in step S3, RH is set to a station temperature of 1580-1600 ℃ and free oxygen is set to a station of 0.035-0.055%;
As a further preferred aspect of the present invention, in step S3, the RH empty temperature is the liquidus temperature +45-55 ℃;
As a further preferred aspect of the present invention, in the step S3, when the sulfur content of the finished product is not more than 15ppm, it is required to add 3 to 4kg/t of desulfurizing agent after the completion of alloying for 2 to 3 minutes;
As a further preferable mode of the invention, in the step S3, after RH breaking and steel tapping, 1-3kg/t of aluminum-based slag modifier is added;
As a further preferable aspect of the present invention, in step S4, the ladle superheat degree is set to 15-25 ℃ during pouring the molten steel after RH treatment into the ladle;
the thickness of the casting blank obtained after continuous casting is 220mm-320mm, and the width of the casting blank is 1500mm-2500mm.
Through the technical scheme, compared with the prior art, the invention has the following beneficial effects:
1. The RH single-linkage medium plate smelting method provided by the invention cancels implementation means about LF refining in the process flow, and solves the problems of large temperature loss and large power consumption caused by long process flow and long time of molten steel in a ladle;
2. according to the RH single-linkage medium plate smelting method provided by the invention, in the implementation process, after the smelting of the rotary furnace, the RH vacuum treatment is directly carried out, so that the generation of deoxidized products is reduced;
3. The RH single-linkage medium plate smelting method provided by the invention omits the calcium treatment operation, reduces the production cost, and simultaneously avoids the environmental pollution and the deterioration of the cleanliness of molten steel.
Detailed Description
The present invention will now be described in further detail.
As described in the background art, the current smelting technology of the medium plate mainly comprises KR desulfurization, converter smelting, LF refining, (RH refining/VD treatment) and continuous casting, and the following three problems exist in the process means: 1) The process flow is long, the molten steel is long in package time, the temperature loss is large, and the power consumption is large; 2) The primary deoxidization products are more, and are difficult to effectively remove; 3) And the calcium treatment operation increases the cost, pollutes the environment and deteriorates the cleanliness of molten steel. Obviously, reducing the energy consumption of the smelting process of the medium plate and improving the inclusion control level are the problems to be solved in the current production of the medium plate.
In order to solve the problems, the application provides a smelting method of an RH single-linkage medium plate aiming at the medium plate, which comprises the following steps of:
Step S1: KR desulfurization is carried out, the molten iron is desulfurized, slag skimming is carried out on the molten iron after desulfurization is finished, standing is carried out for 3-5min, and secondary slag skimming is carried out until no desulfurization slag exists on the surface of the molten iron, wherein the sulfur content in the molten iron after desulfurization is finished is less than or equal to 0.0010%;
step S2: converter smelting, namely carrying out converter smelting on the molten steel subjected to desulfurization treatment in the step S1;
step S3: RH treatment, namely, directly carrying out RH treatment on the converter molten steel obtained in the step S2 after boiling tapping, carrying out alloying according to preset target components for 7-10min, carrying out clean circulation for 10-12min after alloying is completed, carrying out RH emptying tapping, and adding 1-3kg/t of slag surface deoxidizer after RH emptying tapping.
It should be noted here that when the sulfur content of the finished product is less than or equal to 15ppm, it is required to add 3-4kg/t of desulfurizing agent after alloying is completed for 2-3min so as to meet the requirement of lower sulfur content;
After molten steel starts to circulate in a vacuum chamber, oxygen is blown in through an oxygen gun, the oxygen blowing amount is (emptying temperature-arrival temperature +22+a) multiplied by 6.7m 3, the aluminum adding amount is (emptying temperature-arrival temperature +22+a) multiplied by 7.5kg, wherein a depends on the carbon content of a finished product, the carbon content of the finished product is less than 0.06%, the value of a is 10, the carbon content of the finished product is more than or equal to 0.06% and less than 0.1%, the value of a is 20, and when the carbon content of the finished product is more than or equal to 0.1%, the value of a is 25;
Step S4: and (3) continuous casting, namely continuous casting is carried out on the molten steel obtained in the step (S3) to obtain a casting blank.
Compared with the prior art, the smelting method provided by the application omits the operation flow of LF refining, directly tapping steel to the RH treatment procedure for boiling tapping after converter smelting, ensures that certain oxygen content is provided in the smelting process, creates conditions for subsequent carbon deoxidation by the non-deoxidation operation, and can reduce the generation of deoxidized products.
Of course, in the smelting process, each step needs to be reasonably laid out in order to achieve the final purpose. In the step S2, when the converter is smelted, the ratio of the scrap steel is 10% -15%, and the sulfur content in the scrap steel is less than or equal to 0.005%; the alkalinity of final slag at the end of converting is 3.0-3.5, the carbon content at the end of the converter is 0.04-0.06%, the free oxygen at the end is 0.04-0.06%, the temperature at the end is 1640-1660 ℃, and the sulfur content at the end of the converter is less than or equal to 0.003%. When the converter is tapped, 2-3kg/t lime is added in the transferring process of molten steel from the converter to a ladle, and after tapping, 1-2kg/t of steel aluminum-based slag modifier is added on the surface of the molten steel.
Regarding the RH treatment in the step S3, which is the most innovative point of the application, after the molten steel circulates in the vacuum chamber, the oxygen content is set by an oxygen lance, the RH to station temperature is 1580-1600 ℃, the free oxygen to station is 0.035-0.055%, the RH breaking temperature is liquidus temperature +45-55 ℃, and 1-3kg/t steel of aluminum-based slag modifier is added after RH breaking. Meanwhile, when the sulfur content of the finished product is less than or equal to 15ppm, 3-4kg/t of desulfurizing agent is added after alloying is completed for 2-3 min. The related setting method can realize stable production of high-efficiency low-energy-consumption smelting for the medium plate after the LF process is canceled, and simultaneously reduce the number density of inclusions in molten steel.
In the traditional process flow, the LF refining process mainly consumes electric energy to meet the temperature requirement of the steelmaking process, the electric energy is converted into temperature, the components, particularly the sulfur content, are subjected to relevant adjustment, the whole process takes a longer time period, the LF refining process has important irreplaceable functions in the process flow, and the LF refining process is canceled, so that the production efficiency is substantially improved. Because the temperature adjustment is indispensable in the smelting process, the RH treatment is directly carried out after the converter is smelted, in the RH vacuum treatment process, the decarburization procedure contained in the RH vacuum treatment process directly compensates the temperature in the whole smelting process through chemical reaction (aluminum oxygen reaction), meanwhile, oxygen blowing and aluminum adding are carried out in the decarburization stage for temperature adjustment, and under the condition of high aluminum oxygen saturation, the reaction product can be quickly nucleated and efficiently removed; meanwhile, due to the elimination of LF refining, carbon emission in the whole smelting process is reduced, and the environmental protection characteristic is improved.
Regarding the continuous casting of the step S4, the superheat degree of the tundish is set to be 15-25 ℃ in the process of pouring the molten steel after RH treatment into the tundish; the thickness of the casting blank obtained after continuous casting is 220-320mm, and the width of the casting blank is 1500-2500mm.
The method is the whole process of the RH single-linkage medium plate smelting method, and realizes the stable production of eliminating the high-efficiency low-energy-consumption medium plate smelting of the LF process, reducing the quantity of one-time deoxidization products and improving the inclusion control level through a converter process precise sulfur control technology, an RH treatment process chemical heat heating technology, an oxygen-blowing aluminum-adding heating inclusion control technology, an RH treatment process temperature precise control technology and the like.
To further embody the advantages of the application, applicant provides a number of specific embodiments for verification.
Examples
Example 1
The RH single-linkage medium plate smelting method provided by the application is applied to steel grade X65, the ladle loading amount is 180t, wherein the carbon content of a finished product is 0.03-0.05%, and the sulfur content of the finished product is less than 0.0015%. The process flow comprises KR desulfurization, converter smelting, RH treatment and continuous casting.
Step S1: KR desulfurization: after desulfurization, the sulfur content of molten iron is 0.0005-0.0010%, after desulfurization is finished, carrying out first slag skimming operation, standing for 3min, carrying out second slag skimming, and after slag skimming, requiring no desulfurization slag on the surface of molten iron;
Step S2: converter blowing or electric furnace smelting: the ratio of the scrap steel is 11% -14%, and the sulfur content in the scrap steel is less than or equal to 0.005%. The alkalinity of final slag at the end of converting is 3.0-3.5, the carbon content at the end of the converter is 0.04-0.06%, the free oxygen at the end is 0.04-0.06%, the temperature at the end is 1640-1660 ℃, and the sulfur content at the end of the converter is less than or equal to 0.003%. 2-3kg/t of lime is added in converter tapping, and 1-2kg/t of steel is added after tapping is finished.
Step S3: RH treatment: RH to station temperature 1580-1600 ℃ and to station free oxygen 0.035-0.055%. After the molten steel circulates in the vacuum chamber, oxygen is blown in through an oxygen gun, the blowing amount of the oxygen is (breaking temperature-reaching station temperature +22+a) multiplied by 6.7m 3, the adding amount of the aluminum is (breaking temperature-reaching station temperature +22+a) multiplied by 7.5kg, wherein a=10, RH treatment is carried out for 7-10min, alloying is carried out according to target components, after alloying is completed, the clean circulation is carried out for 10-12min, and RH breaking and tapping are carried out. After RH breaking, adding 1-3kg/t of slag surface deoxidizer. The RH burst temperature is typically set to 1569-1579 ℃.
In example 1, the limiting conditions were specifically set as shown in the following table:
When the sulfur content of the finished product is less than or equal to 15ppm, 3-4kg/t of desulfurizing agent is required to be added after alloying is completed for 2-3 min.
Step S4: continuous casting: the superheat degree of the tundish is 15-25 ℃. The thickness of the casting blank is 220mm, and the width of the casting blank is 1680mm.
By the embodiment 1, the smelting time of external refining is shortened by 30-40min, the LF smelting electricity consumption is reduced by 22-26 DEG/t steel, the production efficiency of the medium plate is improved, and the energy consumption in the medium plate smelting process is reduced; meanwhile, the quantity of deoxidized products in the production process is reduced, the total oxygen content of the finished product is less than or equal to 15ppm, and the quality level of the medium plate is effectively improved.
Example 2
The RH single-linkage medium plate smelting method provided by the application is applied to steel grade EH36, the ladle loading amount is 180t, wherein the carbon content of a finished product is 0.065-0.093%, and the sulfur content of the finished product is less than 0.0030%. The process flow comprises KR desulfurization, converter smelting, RH treatment and continuous casting.
Step S1: KR desulfurization: after desulfurization, the sulfur content of the molten iron is less than or equal to 0.0010 percent, after desulfurization is finished, the first slag skimming operation is carried out, after standing for 5min, the second slag skimming operation is carried out, and no desulfurization slag is required to be arranged on the surface of the molten iron after slag skimming;
Step S2: converter blowing or electric furnace smelting: the ratio of the scrap steel is 10% -15%, and the sulfur content in the scrap steel is less than or equal to 0.005%. The alkalinity of final slag at the end of converting is 3.0-3.5, the carbon content at the end of the converter is 0.04-0.06%, the free oxygen at the end is 0.04-0.06%, the temperature at the end is 1640-1660 ℃, and the sulfur content at the end of the converter is less than or equal to 0.003%. 2-3kg/t of lime is added into the steel tapped from the converter, and 1-2kg/t of aluminum-based slag modifier is added after tapping is finished.
Step S3: RH treatment: RH to station temperature 1580-1600 ℃ and to station free oxygen 0.035-0.055%. After the molten steel circulates in the vacuum chamber, oxygen is blown in through an oxygen lance, wherein the blowing-in amount of the oxygen is (breaking temperature-reaching station temperature +22+a) ×6.7m 3, and the adding amount of the aluminum is (breaking temperature-reaching station temperature +22+a) ×7.5kg, wherein the value of a is 20. And carrying out RH treatment for 7-10min, alloying according to the target components, and carrying out clean circulation for 10-12min after alloying is completed, so that RH is used for breaking the blank and tapping. After RH breaking, adding 1-3kg/t of slag surface deoxidizer. The RH burst temperature is typically set to 1567-1577 ℃.
In example 2, the limiting conditions were specifically set as shown in the following table:
When the sulfur content of the finished product is less than or equal to 15ppm, 3-4kg/t of desulfurizing agent is required to be added after alloying is completed for 2-3 min.
Step S4: continuous casting: the superheat degree of the tundish is 15-25 ℃. The thickness of the casting blank is 320mm, and the width of the casting blank 2150mm.
By the embodiment 2, the smelting time of external refining is shortened by 25-35min, the LF smelting electricity consumption is reduced by 20-25 DEG/t steel, the production efficiency of the medium plate is improved, and the energy consumption in the medium plate smelting process is reduced; meanwhile, the quantity of deoxidized products in the production process is reduced, the total oxygen content of the finished product is less than or equal to 20ppm, and the quality level of the medium plate is effectively improved.
Example 3
The RH single-linkage medium plate smelting method provided by the application is applied to steel grade 14Cr1MoR, and the ladle loading amount is 180t, wherein the carbon content of a finished product is 0.13-0.16%, and the sulfur content of the finished product is less than 0.0040%. The process flow comprises KR desulfurization, converter smelting, RH treatment and continuous casting.
Step S1: KR desulfurization: after desulfurization, the sulfur content of the molten iron is less than or equal to 0.0010 percent, after desulfurization is finished, the first slag skimming operation is carried out, after standing for 4min, the second slag skimming operation is carried out, and no desulfurization slag is required to be arranged on the surface of the molten iron after slag skimming;
Step S2: converter blowing or electric furnace smelting: the ratio of the scrap steel is 10% -15%, and the sulfur content in the scrap steel is less than or equal to 0.005%. The alkalinity of final slag at the end of converting is 3.0-3.5, the carbon content at the end of the converter is 0.04-0.06%, the free oxygen at the end is 0.04-0.06%, the temperature at the end is 1640-1660 ℃, and the sulfur content at the end of the converter is less than or equal to 0.003%. 2-3kg/t of lime is added into the steel tapped from the converter, and 1-2kg/t of aluminum-based slag modifier is added after tapping is finished.
Step S3: RH treatment: RH to station temperature 1580-1600 ℃ and to station free oxygen 0.035-0.055%. After the molten steel circulates in the vacuum chamber, oxygen is blown in through an oxygen lance, wherein the blowing-in amount of the oxygen is (breaking temperature-reaching station temperature +22+a) ×6.7m 3, and the adding amount of the aluminum is (breaking temperature-reaching station temperature +22+a) ×7.5kg, wherein the value of a is 25. And carrying out RH treatment for 7-10min, alloying according to the target components, and carrying out clean circulation for 10-12min after alloying is completed, so that RH is used for breaking the blank and tapping. After RH breaking, adding 1-3kg/t of slag surface deoxidizer. The RH burst temperature is usually set to 1557-1567 ℃.
In example 3, the limiting conditions were specifically set as shown in the following table:
When the sulfur content of the finished product is less than or equal to 15ppm, 3-4kg/t of desulfurizing agent is required to be added after alloying is completed for 2-3 min.
Step S4: continuous casting: the superheat degree of the tundish is 15-25 ℃. The thickness of the casting blank is 220mm, and the width of the casting blank is 1890mm.
Through the embodiment 3, the smelting time of external refining is shortened by 30-40min, the LF smelting electricity consumption is reduced by 20-25 DEG/t steel, the production efficiency of the medium plate is improved, and the energy consumption in the medium plate smelting process is reduced; meanwhile, the quantity of deoxidized products in the production process is reduced, the total oxygen content of the finished product is less than or equal to 15ppm, and the quality level of the medium plate is effectively improved.
In conclusion, through implementation of the three embodiments, the applicant finds that the RH single-linkage medium plate smelting method provided by the application shortens the smelting time, improves the production efficiency of the medium plate and reduces the energy consumption in the medium plate smelting process; meanwhile, the quantity of deoxidized products in the production process is reduced, the quality level of the medium plate is effectively improved, and the method is suitable for large-scale popularization.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The meaning of "and/or" in the present application means that each exists alone or both exist.
"Connected" as used herein means either a direct connection between components or an indirect connection between components via other components.
With the above-described preferred embodiments according to the present invention as an illustration, the above-described descriptions can be used by persons skilled in the relevant art to make various changes and modifications without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the description, but must be determined according to the scope of claims.
Claims (8)
1. The RH single-joint medium plate smelting method is aimed at a medium plate with the thickness of 4.5mm-25mm and the width of more than or equal to 1500mm, and is characterized in that: the method specifically comprises the following steps:
Step S1: KR desulfurization is carried out, the molten iron is desulfurized, slag skimming is carried out on the molten iron after desulfurization is finished, standing is carried out for 3-5min, and secondary slag skimming is carried out until no desulfurization slag exists on the surface of the molten iron, wherein the sulfur content in the molten iron after desulfurization is finished is less than or equal to 0.0010%;
step S2: converter smelting, namely carrying out converter smelting on the molten steel subjected to desulfurization treatment in the step S1;
Step S3: RH treatment, namely, directly carrying out RH treatment on the converter molten steel obtained in the step S2 after boiling tapping, wherein the RH treatment lasts for 7-10min, alloying is carried out according to preset target components, and after alloying is completed, the net circulation lasts for 10-12min, and RH breaks the blank tapping;
After molten steel starts to circulate in a vacuum chamber, oxygen is blown in through an oxygen gun, the oxygen blowing amount is (emptying temperature-arrival temperature +22+a) multiplied by 6.7m 3, the aluminum adding amount is (emptying temperature-arrival temperature +22+a) multiplied by 7.5kg, wherein a depends on the carbon content of a finished product, the carbon content of the finished product is less than 0.06%, the value of a is 10, the carbon content of the finished product is more than or equal to 0.06% and less than 0.1%, the value of a is 20, and when the carbon content of the finished product is more than or equal to 0.1%, the value of a is 25;
Step S4: and (3) continuous casting, namely continuous casting is carried out on the molten steel obtained in the step (S3) to obtain a casting blank.
2. The RH single-linked medium plate smelting method according to claim 1, wherein: in the step S2, when the converter is smelted, the ratio of the scrap steel is 10% -15%, and the sulfur content in the scrap steel is less than or equal to 0.005%;
the alkalinity of final slag at the end of converting is 3.0-3.5, the carbon content at the end of the converter is 0.04-0.06%, the free oxygen at the end is 0.04-0.06%, the temperature at the end is 1640-1660 ℃, and the sulfur content at the end of the converter is less than or equal to 0.003%.
3. The RH single-linked medium plate smelting method according to claim 1, wherein: in the step S2, 2-3kg/t lime is added in the transferring process of molten steel from a converter to a ladle when the converter is tapped, and 1-2kg/t of steel aluminum-based slag modifier is added on the surface of the molten steel after tapping is finished.
4. The RH single-linked medium plate smelting method according to claim 1, wherein: in the step S3, the RH to station temperature is set to 1580-1600 ℃ and the free oxygen to station is set to 0.035-0.055%.
5. The RH single-linked medium plate smelting method according to claim 1, wherein: in the step S3, the RH breaking temperature is liquidus temperature +45-55 ℃.
6. The RH single-linked medium plate smelting method according to claim 1, wherein: in the step S3, the sulfur content of the finished product is less than or equal to 15ppm, and 3-4kg/t of desulfurizing agent is required to be added after alloying is completed for 2-3 min.
7. The RH single-linked medium plate smelting method according to claim 1, wherein: in the step S3, after RH breaks and vacates steel, 1-3kg/t of aluminum-based slag modifier is added.
8. The RH single-linked medium plate smelting method according to claim 1, wherein: in the step S4, the superheat degree of the tundish is set to be 15-25 ℃ in the process of pouring the molten steel treated by RH into the tundish;
the thickness of the casting blank obtained after continuous casting is 220mm-320mm, and the width of the casting blank is 1500mm-2500mm.
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