A method for producing a high-carbon high-silicon aluminum-containing steel

Abstract

The application relates to the technical field of steel metallurgy, and discloses a production method of high-carbon high-silicon aluminum-containing steel. In the production method, the molten steel is deoxidized and alloyed and pre-slagging is carried out during tapping of a converter, slagging and diffusion deoxidation are carried out during refining, the total oxygen content of the molten steel is sufficiently reduced, then aluminum wire is fed after the total oxygen content of the molten steel is extremely low at the end of the refining, most of the aluminum is ensured to melt into the molten steel, and a large amount of alumina inclusions is avoided, which can prevent or reduce the occurrence of nozzle clogging on one hand and improve the cleanliness of the molten steel and the yield of the aluminum on the other hand.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel metallurgy, and particularly relates to a production method of high-carbon high-silicon aluminum-containing steel. BACKGROUND

[0002] Cable steel is a kind of high-end steel, which has high requirements on strength, toughness and corrosion resistance. In recent years, with the gradual improvement of industry standards, cable steel is developing towards high strengthening and light weight. Adding high content of C, Si and Mn elements in steel can effectively improve the strength and plasticity of steel, and in order to make the steel have good strength and toughness, the steel often contains a certain content of Al element.

[0003] For example, the C and Si contents of SWRS87Si, SWRS92Si, SWRS96Si and other cable steels are high, and at the same time, 50-300ppm of Al is required to exist in the steel, which belongs to high-carbon high-silicon aluminum-containing steel. In addition to adding silicon, manganese and other alloys during converter tapping, a certain amount of aluminum block also needs to be added, which will cause Al2O3 inclusions in the molten steel obtained by converter tapping. The existence of Al2O3 inclusions leads to a high overall melting point of inclusions, and further leads to the problem of nozzle clogging during casting, causing non-planned stop casting in the continuous casting process. SUMMARY

[0004] The inventors found that the reason why the related art produces the problem of nozzle clogging when producing high-carbon high-silicon aluminum-containing steel is that: (1) in high-carbon high-silicon aluminum-containing steel, due to the high C and Si contents, the liquidus temperature of the molten steel is low, and the flowability of the molten steel is poor, which easily causes the problem of nozzle clogging; (2) in the related art, calcium wire is usually added to modify the Al2O3 inclusions in the molten steel, however, the high content of Si in the molten steel easily participates in the deoxidation reaction, resulting in a high content of SiO2 in the inclusions, and compared with Al2O3, Ca wire is more likely to react with SiO2, so the calcium wire rarely converts Al2O3 inclusions into low-melting-point calcium aluminate inclusions, and therefore the modification effect of calcium treatment on Al2O3 inclusions is poor, and the content of Al2O3 in the inclusions still maintains at a high level; (3) in the related art, aluminum is usually added for deoxidation during the converter tapping process, however, the addition of aluminum is too early, and the oxidation amount of aluminum is too much, which not only increases the Al2O3 inclusions in the molten steel, but also reduces the aluminum yield and the purity of the molten steel.

[0005] Therefore, the present application provides a production method of high-carbon high-silicon aluminum-containing steel to solve the problem of nozzle clogging during casting caused by the existence of a large amount of Al2O3 inclusions in the production of high-carbon high-silicon aluminum-containing steel in the related art.

[0006] In a first aspect, the present application provides a production method of high-carbon high-silicon aluminum-containing steel, comprising the following steps:

[0007] converter tapping, the molten steel is deoxidized and alloyed and pre-slagging during tapping to obtain a tapped molten steel; wherein after the tapping is completed, the content of FeO and MnO in the obtained slag satisfies (FeO+MnO)≤3.0%, and the total oxygen content of the obtained molten steel is ≤40ppm;

[0008]

[0009] the refined molten steel is subjected to continuous casting treatment.

[0010] In the above production method provided by the present application, the total oxygen content of the molten steel is sufficiently reduced by deoxidizing and alloying the molten steel during converter tapping, and by slagging and diffusion deoxidizing during refining, and then the aluminum wire is fed after the total oxygen content of the molten steel is extremely low at the end of refining, so that most of the aluminum metal is melted into the molten steel, and the generation of a large amount of alumina inclusions is avoided, which can prevent or reduce the occurrence of nozzle clogging on one hand, and can improve the cleanliness of the molten steel and the yield of aluminum metal on the other hand.

[0011] That is, in the method of the present application, by reducing the total oxygen content of the molten steel and delaying the timing of adding aluminum metal, a large amount of alumina inclusions is effectively avoided, and the problem of nozzle clogging during casting caused by a large number of Al2O3 inclusions in the production of high-carbon high-silicon aluminum-containing steel in the related art is solved, so that the nozzle clogging and blocking during continuous casting is significantly reduced, the unplanned casting interruption in the continuous casting process is effectively avoided, the number of continuous casting ladles per furnace is increased from the original 5-6 ladles to more than 12 ladles, and the production cost is obviously reduced and the product quality is improved.

[0012] In an alternative embodiment, before the aluminum wire is fed after the end of slagging, the temperature of the obtained molten steel is 1550-1570℃;

[0013] Optionally, before the aluminum wire is fed after the end of slagging, the basicity of the obtained slag is 2.0-3.0;

[0014] Optionally, before the aluminum wire is fed after the end of slagging, the obtained molten steel is subjected to a step of fine-tuning of alloying components to make the composition of the molten steel meet the requirements;

[0015] Optionally, when the aluminum wire is fed, the wire feeding speed is 200-300m / min, the bottom blowing flow rate during wire feeding is 100-200NL / min, and the time from wire feeding to soft stirring is ≤8min. ​

[0016] In an alternative embodiment, the deoxidizing and pre-slagging of the molten steel comprises:

[0017] The molten steel is deoxidized and alloyed by using carbon powder, low-titanium and low-aluminum ferrosilicon, metallic manganese and low-carbon ferrochrome, and then pre-slagging is performed by adding lime.

[0018] In an alternative embodiment, the deoxidizing and pre-slagging of the molten steel comprises:

[0019] Optionally, with respect to 130t-140t of molten steel, the carbon powder is added in an amount of 1100kg-1300kg, the low-titanium and low-aluminum ferrosilicon is added in an amount of 2000kg-2400kg, the metallic manganese is added in an amount of 700kg-900kg, the low-carbon ferrochrome is added in an amount of 500kg-700kg, and the lime is added in an amount of 250kg-350kg.

[0020] Optionally, when the pre-slagging is performed, the bottom blowing flow is controlled to be 1000NL / min-1500NL / min.

[0021] In an alternative embodiment, in the low-titanium and low-aluminum ferrosilicon, the sum of the weight percentage contents of titanium and aluminum is not more than 0.5%.

[0022] Optionally, in the low-carbon ferrochrome, the percentage content of carbon is not more than 0.4%.

[0023] In an alternative embodiment, the deoxidizing and pre-slagging of the molten steel comprises:

[0024] In an alternative embodiment, the deoxidizing and pre-slagging of the molten steel comprises:

[0025] Optionally, the synthetic slag comprises, in terms of weight percentage:

[0026] CaO: 30%-36%, SiO2: 20%-26%, Al2O3: 10%-15%, CaF2: 20%-28%, Al: 2%-5%, and other unavoidable impurities.

[0027] In an alternative embodiment, with respect to 130t-140t of molten steel, the lime is added in an amount of 150kg-250kg, the calcium carbide is added in an amount of 20kg-60kg, and the synthetic slag is added in an amount of 50kg-150kg.

[0028] In an alternative embodiment, during the refining of the tapping molten steel, the bottom blowing flow rate is controlled to be 400-500 NL / min during the electrically conductive slagging, and the bottom blowing flow rate is controlled to be 40-80 NL / min during the soft stirring.

[0029] In an alternative embodiment, the chemical composition of the refined molten steel includes, in terms of weight percentage:

[0030] C: 0.8-1.0%, Si: 1.0-1.3%, Mn: 0.7-0.9%, Cr: 0.2-0.4%, Al: 0.01-0.10%, P≤0.02%, S≤0.01%, and the balance of Fe and other unavoidable impurities.

[0031] In an alternative embodiment, during the continuous casting of the refined molten steel, the submerged entry nozzle is controlled to have an argon flow rate of 2-3 NL / min.

[0032] Optionally, during the continuous casting, the inclusion composition in the tundish molten steel includes, in terms of weight percentage: CaO: 20-60%, SiO2: 10-30%, Al2O3: 30-50%.

[0033] Optionally, the continuous casting billet has a cross-sectional dimension of 300 mm x 390 mm, the continuous casting speed is 0.6-0.7 m / min, and the tundish superheat is 20-40°C.

[0034] Optionally, during the continuous casting of the refined molten steel, the ladle is covered, the tundish uses a double-layer structure of high-carbon steel covering agent and carbonized rice husk, the total slag layer thickness is 100-150 mm, the mold uses high-carbon steel protecting slag, and the total slag layer thickness of the protecting slag is 40-60 mm. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the description of the embodiments or the prior art. Obviously, the drawings described below are some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0036] Figure 1 is a ternary phase diagram of the tundish inclusion composition in Example 1 of the present application;

[0037] Figure 2 is a ternary phase diagram of the tundish inclusion composition in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0038] The following examples are provided to better enable those skilled in the art to further understand the application and are not intended to limit the scope of the application. The content and scope of the application are not limited to the best mode for carrying out the application, and any product that is the same or similar to the application obtained by anyone under the guidance of the application or by combining the application with other prior art features falls within the scope of the application.

[0039] The specific experimental steps or conditions not mentioned in the examples can be carried out according to the conventional experimental steps described in the literature in the art or the operation or conditions. The reagents or instruments not mentioned by the manufacturer are conventional reagent products that can be obtained by purchase.

[0040] In order to solve the problems existing in the above-mentioned related technology, according to the first aspect of the present application, a production method of high-carbon high-silicon aluminum-containing steel is provided, comprising the following steps:

[0041] Converter tapping, deoxidizing and alloying the molten steel and pre-slagging during the tapping process to obtain the tapping molten steel; wherein after the tapping is completed, the content of FeO and MnO in the obtained slag satisfies (FeO+MnO)≤3.0%, and the total oxygen content of the obtained molten steel is ≤40ppm;

[0042] Refining the tapping molten steel, and performing slagging and diffusion deoxidizing on the molten steel during the refining process, and feeding aluminum wire after the slagging is completed to obtain the refined molten steel; wherein before the aluminum wire is fed after the slagging is completed, the content of FeO and MnO in the obtained slag satisfies (FeO+MnO)≤1.0%, and the total oxygen content of the obtained molten steel is ≤20ppm;

[0043] Performing continuous casting treatment on the refined molten steel.

[0044] In the above production method, (FeO+MnO)≤3.0% means that the sum of the contents of FeO and MnO does not exceed 3.0%, and (FeO+MnO)≤1.0% means that the sum of the contents of FeO and MnO does not exceed 1.0%. By controlling the (FeO+MnO) content in the pre-slagging and the slagging slag respectively, the slag has low oxidizing property, which is beneficial to the diffusion of oxygen in the molten steel to the slag, and is beneficial to the reduction of the total oxygen content of the molten steel.

[0045] In the above production method provided by the present application, by deoxidizing and alloying the molten steel and pre-slagging during the converter tapping process, and performing slagging and diffusion deoxidizing during the refining process, the total oxygen content of the molten steel is sufficiently reduced, and then the aluminum wire is fed after the total oxygen content of the molten steel is extremely low, which ensures that most of the aluminum metal is melted into the molten steel and avoids the generation of a large amount of aluminum oxide inclusions. This can prevent or reduce the occurrence of nozzle clogging on one hand, and can improve the cleanliness of the molten steel and the recovery rate of aluminum metal on the other hand.

[0046] That is, in the method of the present application, by reducing the total oxygen content of the molten steel and delaying the timing of adding the metallic aluminum, the generation of a large amount of alumina inclusions is effectively avoided, the problem of nozzle clogging during casting caused by the presence of a large amount of Al2O3 inclusions in the high-carbon high-silicon aluminum-containing steel produced in the related art is solved, the situation of nozzle clogging during continuous casting is significantly reduced, the situation of unplanned casting interruption during continuous casting is effectively avoided, the number of continuous casting ladles is increased from the original 5-6 ladles to more than 12 ladles, and the production cost is significantly reduced and the product quality is improved.

[0047] In an optional embodiment, the temperature of the obtained molten steel is 1550-1570°C before the aluminum wire is fed after the end of slagging. Before the aluminum wire is fed, the molten steel is controlled to have a relatively high temperature, so that the metallic aluminum with a relatively low melting point can rush into the bottom layer of the molten steel and quickly melt, reducing the reaction time of the metallic aluminum with other components in the molten steel, and further reducing the content of alumina in the inclusions.

[0048] Optionally, the basicity of the obtained slag is 2.0-3.0 before the aluminum wire is fed after the end of slagging.

[0049] Optionally, before the aluminum wire is fed after the end of slagging, the obtained molten steel is further subjected to a step of fine-tuning of alloying components to make the composition of the molten steel meet the requirements. Specifically, the fine-tuning of alloying components can be performed according to the target chemical composition of the high-carbon high-silicon aluminum-containing steel, and the corresponding elements are added to the molten steel to make the content meet the requirements. For example, when the carbon content in the molten steel does not meet the requirements, carbon powder is added; when the silicon content in the molten steel does not meet the requirements, low-titanium low-aluminum ferrosilicon is added; when the manganese content in the molten steel does not meet the requirements, metallic manganese is added; when the chromium content in the molten steel does not meet the requirements, low-carbon ferrochrome is added.

[0050] Optionally, when the aluminum wire is fed, the feeding speed is 200-300 m / min, the bottom blowing flow rate during feeding is 100-200 NL / min, and the time from feeding to soft stirring is ≤8 min. When the aluminum wire is fed, a faster feeding speed, a lower bottom blowing flow rate, and a shorter time from feeding to soft stirring are used in combination with the timing of adding the aluminum wire, which can effectively reduce the reaction time of the metallic aluminum with calcium silicate inclusions, reduce the content of alumina in silicate inclusions, reduce the reaction of the metallic aluminum with the slag, reduce the oxidation amount of aluminum exposed to air due to the exposure of the molten steel, and reduce the generation of alumina inclusions, thereby improving the cleanliness of the molten steel and the recovery rate of the metallic aluminum.

[0051] In an optional embodiment, the deoxidizing alloying and pre-slagging of the molten steel comprises:

[0052] Carbon powder, low-titanium and low-aluminum ferrosilicon, metallic manganese and low-carbon ferrochrome are used to deoxidize and alloy the molten steel, and then lime is added to preform slag. Carbon powder, low-titanium and low-aluminum ferrosilicon, metallic manganese, low-carbon ferrochrome and lime are added to deoxidize and alloy and preform slag during the tapping process of the converter, which can not only reduce the total oxygen content of the molten steel and the oxidizability of the slag, but also control the type of deoxidation products and avoid the generation of high-melting-point aluminum oxide inclusions by directly adding aluminum to the molten steel during tapping.

[0053] In an alternative embodiment, the deoxidization and alloying is performed at 1 / 3 of the tapping, and the preforming of slag is performed at 2 / 3 of the tapping.

[0054] Optionally, with respect to 130t-140t of molten steel, the carbon powder is added in an amount of 1100kg-1300kg, the low-titanium and low-aluminum ferrosilicon is added in an amount of 2000kg-2400kg, the metallic manganese is added in an amount of 700kg-900kg, the low-carbon ferrochrome is added in an amount of 500kg-700kg, and the lime is added in an amount of 250kg-350kg.

[0055] Optionally, when the preforming of slag is performed, the bottom blowing flow is controlled to be 1000NL / min-1500NL / min. A larger bottom blowing flow is used during tapping, which, in combination with the mixing and stirring of the molten steel, can enhance the mixing and stirring between the slag and the molten steel, which is conducive to the removal of a large amount of non-metallic inclusions by slag washing and the control of the type of deoxidation products to be converted to calcium silicate. In addition, in combination with the timing of the feeding of aluminum wire, the calcium silicate deoxidation products react with aluminum to generate silico-aluminates, which are low-melting-point inclusions, so as to avoid or reduce the generation of aluminum oxide inclusions.

[0056] In an alternative embodiment, in the low-titanium and low-aluminum ferrosilicon, the sum of the weight percentage contents of titanium and aluminum is not more than 0.5%.

[0057] Optionally, in the low-carbon ferrochrome, the percentage content of carbon is not more than 0.4%.

[0058] In an alternative embodiment, the slag forming and diffusion deoxidization of the molten steel comprises: adding lime, carbide and synthetic slag to the molten steel to perform slag forming and diffusion deoxidization. When the total oxygen content of the molten steel is low at the refining station, the slag forming and diffusion deoxidization by adding lime, carbide and synthetic slag can further reduce the total oxygen content of the molten steel and the oxidizability of the slag.

[0059] Optionally, the synthetic slag comprises, in terms of weight percentage:

[0060] CaO: 30%-36%, SiO2: 20%-26%, Al2O3: 10%-15%, CaF2: 20%-28%, Al: 2%-5% and other unavoidable impurities.

[0061] In an alternative embodiment, the amount of lime added is 150 kg to 250 kg, the amount of calcium carbide added is 20 kg to 60 kg, and the amount of synthetic slag added is 50 kg to 150 kg, relative to 130 t to 140 t of molten steel.

[0062] In an alternative embodiment, during refining of the molten steel tapped, the bottom blowing flow rate is controlled to be 400 NL / min to 500 NL / min during electrically conductive slagging, and the bottom blowing flow rate is controlled to be 40 NL / min to 80 NL / min during soft stirring. By controlling the bottom blowing flow rate, the molten steel is prevented from being exposed for a long time, which is conducive to reducing oxidation of aluminum and generation of aluminum oxide inclusions.

[0063] In an alternative embodiment, the chemical composition of the refined molten steel includes, in terms of weight percentage:

[0064] C: 0.8% to 1.0%, Si: 1.0% to 1.3%, Mn: 0.7% to 0.9%, Cr: 0.2% to 0.4%, Al: 0.01% to 0.10%, P≤0.02%, S≤0.01%, and the balance of Fe and other unavoidable impurities.

[0065] In an alternative embodiment, during continuous casting of the refined molten steel, protective casting is used, and the argon flow rate of the submerged nozzle is controlled to be 2 NL / min to 3 NL / min.

[0066] Optionally, during the continuous casting process, the inclusion composition in the tundish molten steel includes, in terms of weight percentage: CaO: 20% to 60%, SiO2: 10% to 30%, Al2O3: 30% to 50%.

[0067] Optionally, the cross-sectional size of the continuous casting billet is 300 mm x 390 mm, the continuous casting speed is 0.6 m / min to 0.7 m / min, and the tundish superheat is 20°C to 40°C.

[0068] Optionally, during continuous casting of the refined molten steel, a ladle cover is added, the tundish uses a double-layer structure of a high-carbon steel covering agent and carbonized rice husk, the total slag layer thickness is 100 mm to 150 mm, and the mold uses a high-carbon steel protective slag, and the total slag layer thickness of the protective slag is 40 mm to 60 mm.

[0069] In the continuous casting process, measures such as production rhythm control and continuous casting protective casting can avoid generation of high-melting-point aluminum oxide inclusions in the entire process from converter tapping to casting, thereby avoiding nozzle clogging.

[0070] As a particularly preferred embodiment, the production method of the present application adds carbon powder, low-titanium and low-aluminum ferrosilicon, metallic manganese, low-carbon ferrochrome and lime for deoxidation and alloying and pre-slagging during the converter tapping process, which not only reduces the total oxygen content of the molten steel and the oxidizability of the slag, but also controls the type of deoxidation products to avoid the generation of high-melting-point alumina inclusions by directly adding aluminum for deoxidation during the converter tapping; the molten steel is mixed and stirred by increasing the bottom blowing flow during tapping, which is beneficial to the removal of a large amount of non-metallic inclusions by slag washing and the control of the type of deoxidation products to calcium silicate; under the premise that the total oxygen content of the molten steel is low and the inclusions are of calcium silicate type during the refining process, the slagging and diffusion deoxidation are performed by adding lime, calcium carbide and synthetic slag, which further reduces the total oxygen content of the molten steel and the oxidizability of the slag; the composition of the molten steel is adjusted by adding alloys, and the aluminum wire is fed at a relatively fast speed after the composition and temperature of the molten steel meet the standards, because the temperature of the molten steel is high and the melting point of the metallic aluminum is low, the fed aluminum wire rapidly melts after being punched into the bottom layer of the molten steel; the total oxygen content of the molten steel is extremely low, most of the metallic aluminum is melted into the molten steel, and part of the metallic aluminum reacts with the calcium silicate in the molten steel to generate silicate inclusions with low melting point; the free oxygen content in the molten steel is extremely low, so the amount of alumina inclusions generated by the reaction of the metallic aluminum and the free oxygen is small; by delaying the timing of adding the metallic aluminum, reducing the bottom blowing flow and increasing the feeding speed of the aluminum wire during the wire feeding, and shortening the time from the wire feeding to the soft stirring, the reaction time of the metallic aluminum and the calcium silicate can be reduced, the alumina content in the silicate inclusions can be reduced, the reaction of the metallic aluminum and the slag can be reduced, the oxidation of the aluminum exposed to the air due to the exposure of the molten steel can be reduced, the generation of alumina inclusions can be reduced, and the cleanliness of the molten steel and the yield of the metallic aluminum can be improved. At the same time, combined with the control of the production rhythm and the protective casting during continuous casting, the generation of high-melting-point alumina inclusions during the whole process from the converter tapping to the casting can be avoided, so that the occurrence of the nozzle clogging can be avoided.

[0071] The present application has the following advantages: ① By optimizing the deoxidation and slagging method, the total oxygen content of the molten steel and the oxidizability of the slag are reduced, and the type of deoxidation products is controlled; ② Under the premise that the total oxygen content of the molten steel is extremely low, the aluminum feeding method of the molten steel is optimized, the yield of the metallic aluminum is improved, the generation of high-melting-point alumina inclusions and the alumina content in the silicate inclusions are reduced; ③ By controlling the bottom blowing flow, the feeding speed of the aluminum wire and the production rhythm, the reaction between the metallic aluminum and the air and the slag is reduced, and the oxidation of the metallic aluminum is reduced; ④ Combined with the protective casting during continuous casting and the measures of keeping the nozzle in a slightly positive pressure, the generation of high-melting-point alumina inclusions is reduced during the whole smelting process, the nozzle clogging during the continuous casting process is significantly reduced, the number of continuous casting ladles is increased from 5-6 ladles to more than 12 ladles, the production cost is significantly reduced, the product quality is improved, and the application effect is significantly improved.

[0072] The present application will be further described in detail below in combination with specific examples, which cannot be understood as limiting the scope of the present application.

[0073] Example 1

[0074] A high-carbon high-silicon aluminum-containing steel is prepared by the following method:

[0075] (1) After the end of steelmaking, converter tapping is performed, 1150 kg of carbon powder, 2200 kg of low-titanium low-aluminum ferrosilicon (the sum of the weight percentage contents of titanium and aluminum is 0.2%), 780 kg of metallic manganese, and 580 kg of low-carbon ferrochrome (the weight percentage content of carbon is 0.2%) are added at 1 / 3 of the tapping time for deoxidation and alloying, then 300 kg of lime is added at 2 / 3 of the tapping time for pre-slagging, and the bottom blowing flow rate is controlled at 1200 NL / min during the tapping of the converter, and 135 t of tapping molten steel is obtained after the end of the tapping of the converter;

[0076] wherein the sum of the contents of FeO and MnO in the slag obtained after the end of the tapping is 2%, and the total oxygen content of the obtained molten steel is 32 ppm;

[0077] (2) The 135 t of tapping molten steel obtained in step (1) is refined, 200 kg of lime, 40 kg of carbide, and 100 kg of synthetic slag are added during the refining process, then power is passed for slagging and diffusion deoxidation, after the end of the slagging, the obtained molten steel is subjected to fine adjustment of alloying components so as to meet the requirements, then aluminum wire is fed to obtain refined molten steel;

[0078] wherein the components of the synthetic slag are: CaO: 33%, SiO2: 24%, Al2O3: 14%, CaF2: 25%, Al: 4%, and other unavoidable impurities;

[0079] After the end of the slagging, the obtained slag basicity is 2.8, the sum of the contents of FeO and MnO in the slag is 0.5%, the total oxygen content of the obtained molten steel is 15 ppm, the temperature of the molten steel is 1560°C, the bottom blowing flow rate is 450 NL / min when the slag is electrically melted, the feeding speed of the aluminum wire is 250 m / min, the time of feeding the wire to soft stirring is 5 min, the bottom blowing flow rate is 150 NL / min when the wire is fed, and the bottom blowing flow rate is 55 NL / min when the wire is soft stirred;

[0080] The chemical components of the obtained refined molten steel are: C: 0.92%, Si: 1.14%, Mn: 0.82%, Cr: 0.31%, Al: 0.06%, P: 0.012%, S: 0.008%, and the balance of Fe and other unavoidable impurities;

[0081] (3) The refined molten steel obtained in step (2) is subjected to continuous casting treatment, and in the continuous casting process, protective casting is adopted, a ladle cover is added, a tundish is provided with a double-layer structure of high-carbon steel covering agent and carbonized rice husk, the total slag layer thickness is controlled to be 120 mm, a high-carbon steel covering agent is used in the mold, the total slag layer thickness of the covering agent is 55 mm, and the argon flow rate of the submerged nozzle is 2.5 NL / min. The cross section of the continuous casting billet is 300 mm x 390 mm, the continuous casting speed is 0.66 m / min, and the superheat of the tundish is 32°C. Through sampling in the tundish, the average composition of the inclusions is CaO: 43%, SiO2: 12%, Al2O3: 40%, and MgO: 5%, and the composition distribution of the inclusions in the ternary phase diagram is as shown in Figure 1 .

[0082] According to the method of the present embodiment, 13 heats are cast by continuous casting, the submerged nozzle is not clogged, and the stopper curve is smooth; the average oxygen content in the finished product sample is 18 ppm, the average density of inclusions above 5 μm is 55 pieces / cm 2 , and the recovery rate of aluminum is 60%.

[0083] Example 2

[0084] A high-carbon high-silicon aluminum-containing steel is prepared according to the following method:

[0085] (1) After the end of steelmaking, the converter is tapped, 1100 kg of carbon powder, 2000 kg of low-titanium low-aluminum ferrosilicon (the sum of the weight percentages of titanium and aluminum is 0.2%), 700 kg of metallic manganese, and 500 kg of low-carbon ferrochrome (the weight percentage of carbon is 0.2%) are added at 1 / 3 of the tapping time for deoxidation and alloying, then 250 kg of lime is added at 2 / 3 of the tapping time for pre-slagging, and the bottom blowing flow rate is controlled to be 1000 NL / min during the tapping of the converter, and 130 t of molten steel is obtained after the end of the tapping of the converter;

[0086] Among them, the sum of the contents of FeO and MnO in the slag obtained after the end of the tapping is 2.2%, and the total oxygen content of the obtained molten steel is 33 ppm;

[0087] (2) The 130 t of molten steel obtained in step (1) is subjected to refining, and during the refining process, 150 kg of lime, 20 kg of carbide, and 50 kg of synthetic slag are added, then electricity is passed for slagging and diffusion deoxidation, after the end of the slagging, the composition of the molten steel is adjusted to meet the requirements, then aluminum wire is fed, and refined molten steel is obtained;

[0088] Among them, the composition of the synthetic slag is: CaO: 33%, SiO2: 24%, Al2O3: 14%, CaF2: 25%, Al: 4%, and other unavoidable impurities;

[0089] After the end of slagging, the resulting slag basicity is 2.4, the sum of the contents of FeO and MnO in the slag is 0.7%, the total oxygen content of the resulting molten steel is 17 ppm, the temperature of the molten steel is 1550°C, the bottom blowing flow rate during the electric slagging is 400 NL / min, the wire feeding speed of the aluminum wire is 200 m / min, the time of wire feeding to soft stirring is 5 min, the bottom blowing flow rate during wire feeding is 100 NL / min, and the bottom blowing flow rate during soft stirring is 40 NL / min;

[0090] The chemical composition of the resulting refined molten steel is: C: 0.82%, Si: 1.10%, Mn: 0.76%, Cr: 0.25%, Al: 0.08%, P: 0.014%, S: 0.009%, and the balance of Fe and other unavoidable impurities;

[0091] (3) The refined molten steel obtained in step (2) is subjected to continuous casting treatment, and in the continuous casting process, protective casting is used, a ladle cover is added, a high-carbon steel cover agent and carbonized rice husk double-layer structure are used in the tundish, the total slag layer thickness is controlled to be 100 mm, a high-carbon steel protection slag is used in the mold, the total slag layer thickness of the protection slag is 40 mm, and the argon flow rate of the submerged entry nozzle is 2.0 NL / min. The cross section of the continuous casting billet is 300 mm x 390 mm, the continuous casting speed is 0.66 m / min, and the tundish superheat is 20°C. Through sampling in the tundish, the average composition of the inclusions is CaO: 45%, SiO2: 15%, Al2O3: 35%, and MgO: 5%.

[0092] According to the method of the present embodiment, 13 heats are cast by continuous casting, the submerged entry nozzle does not clog, and the stopper curve is smooth; the average oxygen content in the finished product sample is 15 ppm, and the average density of inclusions above 5 μm is 40 pieces / cm 2 , and the yield of metallic aluminum is 52%.

[0093] Example 3

[0094] A high-carbon high-silicon aluminum-containing steel is prepared according to the following method:

[0095] (1) After the end of steelmaking, the converter is tapped, 1300 kg of carbon powder, 2400 kg of low-titanium low-aluminum ferrosilicon (the sum of the weight percentages of titanium and aluminum is 0.2%), 900 kg of metallic manganese, and 700 kg of low-carbon ferrochrome (the weight percentage of carbon is 0.2%) are added at 1 / 3 of the tapping time for deoxidation and alloying, then 350 kg of lime is added at 2 / 3 of the tapping time for pre-slagging, and the bottom blowing flow rate is controlled to be 1500 NL / min during the tapping of the converter, and 136 t of molten steel is obtained after the end of the tapping of the converter;

[0096] Among them, the sum of the contents of FeO and MnO in the resulting slag after the end of the tapping is 2.1%, and the total oxygen content of the resulting molten steel is 26 ppm;

[0097] (2) refining the 136t tapped molten steel obtained in step (1), adding lime 250kg, carbide 60kg and synthetic slag 150kg during the refining, then performing electric smelting and diffusion deoxidation, after the smelting is completed, performing fine adjustment of the alloying components of the obtained molten steel to make the composition of the molten steel meet the requirements, then feeding aluminum wire to obtain refined molten steel;

[0098] wherein the composition of the synthetic slag is: CaO: 33%, SiO2: 24%, Al2O3: 14%, CaF2: 25%, Al: 4% and other unavoidable impurities;

[0099] After the smelting is completed, the obtained slag basicity is 2.9, the sum of the contents of FeO and MnO in the slag is 0.6%, the total oxygen content of the obtained molten steel is 15ppm, the temperature of the molten steel is 1570°C, the bottom blowing flow rate during the electric slagging is 500NL / min, the feeding speed of the aluminum wire is 300m / min, the time of feeding the wire to soft stirring is 5min, the bottom blowing flow rate during the feeding is 200NL / min, and the bottom blowing flow rate during the soft stirring is 80NL / min;

[0100] The chemical composition of the obtained refined molten steel is: C: 0.96%, Si: 1.22%, Mn: 0.83%, Cr: 0.32%, Al: 0.09%, P: 0.010%, S: 0.008% and the balance of Fe and other unavoidable impurities;

[0101] (3) performing continuous casting treatment on the refined molten steel obtained in step (2), using protective casting in the continuous casting process, adding ladle cover, using high-carbon steel covering agent and carbonized rice husk double-layer structure in the tundish, controlling the total slag layer thickness to be 150mm, using high-carbon steel protective slag in the mold, the total slag layer thickness of the protective slag is 60mm, the argon flow rate of the submerged entry nozzle is 3.0NL / min. The cross section of the continuous casting billet is 300mmx390mm, the continuous casting speed is 0.7m / min, and the tundish superheat is 40°C. Through sampling in the tundish, the average composition of the inclusions is CaO: 46%, SiO2: 11%, Al2O3: 37%, MgO: 6%.

[0102] According to the method of the present embodiment, 12 heats of continuous casting are performed, the submerged entry nozzle is not clogged, and the stopper curve is smooth; the average oxygen content in the finished product sample is 16ppm, and the average density of inclusions above 5μm is 42 / cm 2 , and the recovery rate of aluminum is 55%.

[0103] Comparative Example 1

[0104] A high-carbon high-silicon aluminum-containing steel was prepared according to the following method:

[0105] (1) After the end of steelmaking, the converter is tapped, at 1 / 3 of the tapping, 1150 kg of carbon powder, 2200 kg of low-titanium and low-aluminum ferrosilicon (the sum of the weight percentage contents of titanium and aluminum is 0.2%), 780 kg of metallic manganese, 580 kg of low-carbon ferrochrome (the weight percentage content of carbon is 0.2%) are added, 100 kg of aluminum block is added for deoxidation and alloying, at 2 / 3 of the tapping, 300 kg of lime is added for pre-slagging, and the bottom blowing flow is controlled at 1200 NL / min during the tapping of the converter, and 135 t of tapping steel is obtained after the end of the tapping of the converter;

[0106] Among them, the sum of the contents of FeO and MnO in the slag obtained after the end of the tapping is 1.6%, and the total oxygen content of the obtained molten steel is 20 ppm;

[0107] (2) The 135 t of tapping steel obtained in step (1) is refined, 200 kg of lime, 40 kg of carbide and 100 kg of synthetic slag are added during the refining process, and then the electric power is turned on for slagging and diffusion deoxidation, after the end of the slagging, the obtained molten steel is finely tuned for alloy composition to meet the requirements, and the refined molten steel is obtained;

[0108] Among them, the composition of the synthetic slag is: CaO: 33%, SiO2: 24%, Al2O3: 14%, CaF2: 25%, Al: 4%, and other unavoidable impurities;

[0109] After the end of the slagging, the basicity of the obtained slag is 2.8, the sum of the contents of FeO and MnO in the slag is 0.9%, the total oxygen content of the obtained molten steel is 23 ppm, the temperature of the molten steel is 1560℃, the bottom blowing flow is 450 NL / min when the slag is electrified, and the bottom blowing flow is 55 NL / min when the soft stirring is performed;

[0110] The chemical composition of the obtained refined molten steel is: C: 0.91%, Si: 1.20%, Mn: 0.85%, Cr: 0.32%, Al: 0.08%, P: 0.012%, S: 0.009%, and the balance of Fe and other unavoidable impurities;

[0111] (3) The refined molten steel obtained in step (2) is subjected to continuous casting treatment, protective casting is adopted in the continuous casting process, a ladle cover is added to the ladle, a double-layer structure of high-carbon steel covering agent and carbonized rice husk is adopted in the tundish, the total slag layer thickness is controlled to be 120 mm, a high-carbon steel protecting slag is adopted in the mold, the total slag layer thickness of the protecting slag is 55 mm, and the argon flow of the submerged nozzle is 2.5 NL / min. The cross section of the continuous casting billet is 300 mm x 390 mm, the continuous casting speed is 0.66 m / min, and the superheat degree of the tundish is 32℃. Through sampling in the tundish, the average composition of the inclusions is CaO: 16%, SiO2: 12%, Al2O3: 68%, MgO: 4%, and the composition distribution of the inclusions in the ternary phase diagram is as follows: Figure 2shown.

[0112] According to the method of the present comparative example, only 6 heats were cast with the submerged entry nozzle clogging and the stopper curve lifting severely. The average oxygen content in the finished product sample was 25 ppm and the average density of inclusions above 5 μm was 80 pieces / cm 2 The yield of aluminum metal was 29%.

[0113] Obviously, the above embodiments are merely exemplary but not as limitation to the embodiments. Based on the above description, one of ordinary skill in the art can make other different forms of changes or variations. Here, it is not necessary and also impossible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for producing a high-carbon high-silicon aluminum-containing steel, characterized in that, It comprises the following steps: converter tapping, deoxidizing and alloying the molten steel and pre-creating slag during tapping to obtain the tapping molten steel; wherein, after the tapping is completed, the content of FeO and MnO in the obtained slag satisfies (FeO+MnO)≤3.0%, and the total oxygen content of the obtained molten steel is ≤40 ppm; refining the tapping molten steel, creating slag and diffusion deoxidizing the molten steel during the refining, and feeding aluminum wire after the creation of slag is completed to obtain the refined molten steel; wherein, before the aluminum wire is fed after the creation of slag is completed, the content of FeO and MnO in the obtained slag satisfies (FeO+MnO)≤1.0%, and the total oxygen content of the obtained molten steel is ≤20 ppm; carrying out continuous casting treatment on the refined molten steel; the deoxidizing and alloying and pre-creating slag of the molten steel comprises: using carbon powder, low-titanium and low-aluminum ferrosilicon, metal manganese and low-carbon ferrochrome to deoxidize and alloy the molten steel, and then adding lime to pre-create slag; the creating slag and diffusion deoxidizing of the molten steel comprises: adding lime, calcium carbide and synthetic slag to the molten steel to create slag and diffusion deoxidize; the synthetic slag comprises, in terms of weight percentage: CaO: 30% to 36%, SiO2: 20% to 26%, Al2O3: 10% to 15%, CaF2: 20% to 28%, Al: 2% to 5%, and other unavoidable impurities; when the tapping molten steel is refined, the bottom blowing flow is controlled to be 400 NL / min to 500 NL / min during power slagging, and the bottom blowing flow is controlled to be 40 NL / min to 80 NL / min during soft stirring; when the refined molten steel is treated by continuous casting, protective casting is used, and the argon flow of the submerged entry nozzle is controlled to be 2 NL / min to 3 NL / min; the chemical composition of the refined molten steel comprises: C: 0.8% to 1.0%, Si: 1.0% to 1.3%, Mn: 0.7% to 0.9%, Cr: 0.2% to 0.4%, Al: 0.01% to 0.10%, P≤0.02%, S≤0.01%, and the balance of Fe and other unavoidable impurities.

2. The production method according to claim 1, characterized by, Before the aluminum wire is fed after the creation of slag is completed, the temperature of the obtained molten steel is 1550 ℃ to 1570 ℃; Before the aluminum wire is fed after the creation of slag is completed, the basicity of the obtained slag is 2.0 to 3.0; Before the aluminum wire is fed after the creation of slag is completed, it further comprises the step of fine-tuning the alloying composition of the obtained molten steel to make the composition of the molten steel meet the requirements; When the aluminum wire is fed, the wire feeding speed is 200 m / min to 300 m / min, the bottom blowing flow during wire feeding is 100 NL / min to 200 NL / min, and the time from wire feeding to soft stirring is ≤8 min.

3. The production method according to claim 1, characterized by, The deoxidizing and alloying is carried out at 1 / 3 of the tapping, and the pre-creating slag is carried out at 2 / 3 of the tapping. The adding amount of the carbon powder is 1100 kg to 1300 kg, the adding amount of the low-titanium low-silicon ferroaluminum is 2000 kg to 2400 kg, the adding amount of the metallic manganese is 700 kg to 900 kg, the adding amount of the low-carbon ferrochrome is 500 kg to 700 kg, and the adding amount of the lime of the pre-formed slag is 250 kg to 350 kg, relative to 130 t to 140 t of the molten steel; When the pre-formed slag is formed, the bottom blowing flow is controlled to be 1000 NL / min to 1500 NL / min.

4. The production method according to claim 3, characterized by, In the low-titanium low-silicon ferroaluminum, the sum of the weight percentage contents of titanium and aluminum is not more than 0.5 %; In the low-carbon ferrochrome, the weight percentage content of carbon is not more than 0.4 %.

5. The production method according to claim 1, characterized by, The adding amount of the lime for slagging and diffusion deoxidation of the molten steel is 150 kg to 250 kg, the adding amount of the calcium carbide is 20 kg to 60 kg, and the adding amount of the synthetic slag is 50 kg to 150 kg, relative to 130 t to 140 t of the molten steel.

6. The production method according to claim 1, characterized by, In the continuous casting process, the inclusions in the tundish molten steel include, in weight percentage, CaO: 20 % to 60 %, SiO2: 10 % to 30 %, and Al2O3: 30 % to 50 %; The continuous casting billet has a cross-sectional dimension of 300 mm x 390 mm, and the continuous casting speed is 0.6 m / min to 0.7 m / min, and the tundish superheat is 20 ℃ to 40 ℃. When the refined molten steel is subjected to the continuous casting process, a ladle cover is added, the tundish adopts a double-layer structure of high-carbon steel covering agent and carbonized rice husk, the total slag layer thickness is 100 mm to 150 mm, the mold adopts high-carbon steel protection slag, and the total slag layer thickness of the protection slag is 40 mm to 60 mm.

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