High-cleanliness stranded wire steel preparation method, stranded wire steel and wire rod preparation method

Abstract

The invention relates to a preparation method of high-cleanliness stranded wire steel, a preparation method of the stranded wire steel and a wire rod, and a design application and precise control method of a stranded wire steel refining slag system, which can realize the target effects of rapid slag melting of refining slag, stable desulfurization of molten steel, reduction of steel ladle refractory erosion, precise modification and quantity reduction of Alt and inclusions in steel and the like. And finally, the processability and the mechanical property of the stranded wire steel are improved. In addition, the recycled calcium aluminate casting residues are used for replacing fluorite, and the method has certain benefits in the aspects of smelting cost reduction, solid waste resource utilization and environmental protection.

Description

Technical Field

[0001] The present invention relates to a preparation method of high-purity stranded steel, stranded steel and a preparation method of wire rod, belonging to the technical field of metal smelting. Background Art

[0002] Prestressed steel strands are widely used in fields such as highways, long-span bridges, and high-rise buildings. The wire rod used for manufacturing prestressed steel strands is required to have a low wire breakage rate and stable mechanical properties during the drawing process. Therefore, during the smelting of this type of steel, the types and quantities of inclusions in the steel are extremely strictly required, especially B-type hard inclusions (Al2O3) and high-melting-point complex inclusions in the Ds type. During the actual smelting process, this type of steel uses silicon-deoxidized killed steel, and by strictly controlling the aluminum content in the alloy and slag-making materials, a large amount of Al2O3 inclusions are avoided; during the secondary refining process, a high-alkalinity CaO-SiO2-CaF2-based refining slag is made to complete the tasks of desulfurization and inclusion removal.

[0003] For example, Patent CN202310610976.X discloses a wire rod for steel strands and its preparation method. This technical method uses ferrosilicon and silicomanganese to complete deoxidation alloying, and uses fluorite to participate in refining slag making, and the basicity of the final refining slag is controlled at 2.4 - 2.5. Patent CN202211047282.1 discloses a steel smelting production method for high-strength prestressed steel strands with excellent drawing performance. This technical method uses a Si-Ca-Ba composite deoxidizer to complete the deoxidation of molten steel; during the LF refining process, an aluminum-free slag-making process is adopted to form a CaO-SiO2-CaF2-based refining slag that can adsorb inclusions. The above two steel strand preparation methods have a certain effect on the control of B-type hard inclusions, but the control of high-melting-point CaO(MgO)-SiO2-Al2O3 composite inclusions is extremely unstable, which is not conducive to stabilizing the drawing performance of the wire rod.

[0004] Therefore, it is necessary to provide a preparation method that can improve the cleanliness and mechanical properties of the steel grade. Summary of the Invention

[0005] The present invention provides a preparation method of high-purity stranded steel, stranded steel and a preparation method of wire rod, which realizes the precise modification and quantity control of inclusions in the steel, and improves the cleanliness and mechanical properties of the stranded steel.

[0006] The technical solution adopted by the present invention to solve its technical problems is: A preparation method of high-purity stranded steel, comprising the following steps: Step S1, blast furnace smelting: Low-phosphorus iron ore is smelted in a blast furnace to obtain hot metal. The tapped hot metal enters a ladle, and the temperature of the hot metal in the ladle before being transferred to a converter is ≥1360°C. By mass percentage, the components of the smelted hot metal include: C is 4.10 - 4.80%, Si is 0.20 - 0.60%, Mn is ≤0.35%, P is ≤0.10%, S is ≤0.05%, and Fe and other inevitable impurity components; Step S2, converter smelting: Scrap steel is added, and blowing is carried out with a high-low-low lance position. The basicity of the slag at the end of blowing is 2.8 - 3.3. During the tapping process, ferrosilicon, silicomanganese, high-carbon ferrochrome, calcium aluminate casting residue, lime, and low-nitrogen carbon powder are sequentially added to the ladle, and bottom blowing of the ladle is fully opened during the tapping process. By mass percentage, the components of the tapped molten steel include: C is 0.10 - 0.50%, O is ≤0.06%, and S is ≤0.03%; Among them, the calcium aluminate casting residue is obtained by recycling, and the addition amounts of the calcium aluminate casting residue and lime are determined by the oxygen content in the tapped molten steel. Specifically, When the oxygen content ≤0.02%, 1 kg / t < the weight of the calcium aluminate casting residue ≤1.5 kg / t, and 0.5 kg / t < the weight of the lime ≤1 kg / t; When 0.02% < the oxygen content ≤0.04%, 1.5 kg / t < the weight of the calcium aluminate casting residue ≤2 kg / t, and 1 kg / t < the weight of the lime ≤2 kg / t; When 0.04% < the oxygen content ≤0.06%, 2 kg / t < the calcium aluminate casting residue ≤2.5 kg / t, and 2 kg / t < the weight of the lime ≤3 kg / t; Step S3, LF refining: After the ladle enters the station, bottom blowing is started and electrodes are inserted into the ladle to energize and raise the temperature. Slag-making agents lime and calcium carbide are supplemented and added. Ferrosilicon, silicomanganese, and carbon powder are added to adjust the molten steel composition to the target composition. After the molten steel composition reaches the target composition, soft stirring is started. In the slag at the end of refining, by mass percentage, the components include: the MgO content is ≤5%, the content of (Ca2Al2SiO7 + CaAl2SiO6) is 20 - 30%, and the content of (FeO + MnO) is ≤2%; Step S4, continuous casting: A 150×150 mm square billet continuous caster is used for full-protection casting to form steel. The superheat temperature of the molten steel is set to 10 - 30°C, the drawing speed of the square billet is 2.4 - 2.6 m / min, and the cooling water ratio is 0.24 - 0.26 L / kg; Furthermore, in step S1, after the hot metal obtained by blast furnace smelting enters the ladle, it is covered to achieve heat preservation; Further, in step S2, the total charged amount of converter steel materials is 135 ± 2 t, and the scrap ratio added is 20 - 25%; the tapping temperature of the molten steel is 1620 - 1660 °C, and the slag amount during tapping is ≤ 200 kg; Further, in step S2, during the tapping process, 0.5 - 1 kg / t of ferrosilicon, 8 - 10 kg / t of silicomanganese, 2.5 - 3.5 kg / t of high-carbon ferrochrome, and 3 - 6 kg / t of low-nitrogen carbon powder are added to the ladle; Further, in step S2, the solid particle size of the calcium aluminate tapping slag is 5 - 50 mm, and its chemical composition by mass percentage includes: CaO is 55 - 60%, Al2O3 is 25 - 30%, (FeO + MnO) is ≤ 2%, MgO is ≤ 5%, SiO2 is ≤ 3%, metallic Fe is ≤ 2%, S is ≤ 0.3%, and other inevitable impurity components; Further, in step S2, the bottom blowing of the ladle is continuously carried out for 5 - 10 min during the tapping process, and the bottom blowing argon flow rate is set to 4 - 5 NL / (min·t); Further, in step S3, in the supplementary addition of the slag-making agent, the lime addition amount is 0.5 - 1.0 kg / t, and the calcium carbide addition amount is 0.5 - 0.8 kg / t; the alkalinity of the final slag of refining is 1.6 - 2.0; Further, in step S3, the bottom blowing is started after the ladle enters the station and lasts for 5 - 10 min, and the bottom blowing argon flow rate is set to 2.5 - 4.5 NL / (min·t); The duration of soft stirring is 8 - 12 min, and the bottom blowing argon flow rate is set to 0.5 - 0.9 NL / (min·t); The stranded wire steel obtained by the method for preparing high-cleanliness stranded wire steel mainly includes, by mass percentage: C is 0.81 - 0.84%, Si is 0.18 - 0.22%, Mn is 0.78 - 0.82%, P is ≤ 0.01%, S is ≤ 0.015%, Cr is 0.16 - 0.20%, Alt ≤ 0.003%, T.O ≤ 0.0015%, and Fe and other inevitable impurity components; A method for preparing wire rods, based on the method for preparing high-cleanliness stranded wire steel, continues with step S5, rolling. The heating furnace heats the steel to the preset rolling temperature, and the steel is rolled to the preset specifications through rough rolling and finish rolling in sequence, and a steel stranded wire rod with the specification is made by segmented controlled cooling.

[0007] Through the above technical solutions, compared with the prior art, the present invention has the following beneficial effects: 1. The preparation method of high-cleanliness stranded wire steel provided by the present invention, based on the actual smelting production particularity of relevant factories, uses the recycled calcium aluminate casting residue as raw material and continues to put it into steel smelting to reduce costs, improve resource utilization rate and optimize the smelting process; 2. The preparation method of high-cleanliness stranded wire steel provided by the present invention uses calcium aluminate casting residue to replace fluorite to participate in refining slag making, improves the traditional CaO-SiO2-CaF2 refining slag system to a CaO-SiO2-Al2O3 refining slag system. Without increasing the number of type B hard inclusions with high Al2O3 content, it reduces the content of MgO in the Ds type composite inclusions in the steel and appropriately increases the content of Al2O3 to realize the plasticization of large-size composite inclusions. Specific embodiments

[0008] The present invention will now be further described in detail.

[0009] As described in the background art, currently the typical preparation method of stranded wire steel mainly completes the tasks of desulfurization and inclusion removal of molten steel by strictly controlling the Al content in alloys and slag-making materials and making CaO-SiO2-CaF2 system refining slag in the secondary refining process. This process method has the following disadvantages: (1) Using low-aluminum alloys to complete the alloying of molten steel and using fluorite to accelerate refining slag making both increase the alloy and slag-making material costs in the production of steel strands. (2) The aluminum-free slag-making process leads to a decrease in the Al2O3 content in the CaO(MgO)-SiO2-Al2O3 composite inclusions in molten steel; the use of fluorite in the slag-making process leads to aggravated erosion of magnesia-carbon refractories, and a large amount of MgO enters the molten steel, further leading to an increase in the MgO content in the CaO(MgO)-SiO2-Al2O3 composite inclusions in molten steel; the lower Al2O3 content and higher MgO content in the CaO(MgO)-SiO2-Al2O3 composite inclusions will lead to an increase in the melting point and a decrease in plasticity of the inclusions; a large number of high-melting-point composite inclusions in stranded wire steel will reduce the processing performance and mechanical properties of the material.

[0010] Therefore, to solve the above problems, the present application provides a preparation method of high-cleanliness stranded wire steel, which uses the recycled calcium aluminate casting residue as raw material to replace fluorite to participate in refining slag making and improves the traditional CaO-SiO2-CaF2 refining slag system to a CaO-SiO2-Al2O3 refining slag system. The preparation method also clarifies the basicity of the refining slag, the content and control methods of the key phases MgO, Ca2Al2SiO7 and CaAl2SiO6, and through the optimized refining process, realizes the precise modification and quantity control of inclusions in stranded wire steel, and improves the cleanliness and mechanical properties of stranded wire steel.

[0011] Next, the provided preparation method will be specifically described. Here, taking the smelting process of traditional steel SWRH82B for steel strands as an example, it includes the following steps: Step S1, blast furnace smelting. In order to control the phosphorus content in hot metal and subsequent steel, low-phosphorus iron ore is selected for smelting. The low-phosphorus iron ore is smelted in the blast furnace to obtain hot metal. After the hot metal is tapped and enters the ladle, it is covered to keep warm. The temperature of the hot metal in the ladle before being transferred to the converter is ≥1360 °C. The high temperature is conducive to the progress of chemical reactions during the subsequent converter smelting process, improving the smelting efficiency. At the same time, the heat preservation measures can reduce heat loss and maintain the high-temperature state of the hot metal.

[0012] The composition of the molten steel formed during smelting needs to be strictly controlled. For example, carbon is an important reaction element in the subsequent steelmaking process, and its content has a significant impact on the properties of steel such as strength and hardness; silicon can be used as a deoxidizer during steelmaking and also affects the strength and toughness of steel; manganese can improve the strength of steel and eliminate the hot brittleness of steel caused by sulfur; strictly controlling the content of phosphorus and sulfur can avoid the occurrence of cold brittleness and hot brittleness in steel and ensure the quality of steel. Therefore, it is set that in the hot metal formed during smelting, by mass percentage, each component includes: C is 4.10 - 4.80%, Si is 0.20 - 0.60%, Mn is ≤0.35%, P is ≤0.10%, S is ≤0.05% and Fe and other inevitable impurity components.

[0013] Step S2, converter smelting. The total charge of steel and iron materials in the converter is 135 ± 2 t. Controlling the charge can ensure the stability of the converter smelting process and the consistency of the process. The scrap ratio added is 20 - 25%, which can adjust the temperature of the molten steel and reduce production costs. High-low-low lance positions are used for blowing to optimize the reaction between oxygen and hot metal at different blowing stages and improve the reaction efficiency of decarburization, dephosphorization, etc. The basicity of the slag at the end of blowing is 2.8 - 3.3. The appropriate slag basicity helps to remove impurities such as sulfur and phosphorus in the molten steel and improve the quality of the molten steel. The tapping temperature of the molten steel is 1620 - 1660 °C. During the tapping process, the bottom blowing of the ladle is continuously opened for 5 - 10 min, and the flow rate of argon for bottom blowing is set at 4 - 5 NL / (min·t). The amount of slag flowing down during tapping is ≤200 kg, ultimately ensuring the purity of the molten steel.

[0014] During the tapping process, special attention needs to be paid to the addition sequence of the ladle materials. Ferro-silicon, silico-manganese, high-carbon ferrochrome, calcium aluminate casting residue, lime, and low-nitrogen carbon powder are sequentially added to the ladle. The reasonable addition sequence can ensure that each material plays its full role, accurately adjust the composition of the molten steel, and ultimately achieve that in the molten steel after tapping, by mass percentage, each component includes: C is 0.10 - 0.50%, O is ≤0.06%, S is ≤0.03%. These composition ranges determine the basic properties of the steel.

[0015] The calcium aluminate casting residue adopted herein is an important innovation point of this application. The primary reason for selecting it is based on the special nature of the enterprise where the smelting process of this application is located. It is a smelting enterprise with a relatively large scale. Therefore, a large amount of calcium aluminate casting residue is obtained after the production of multiple production lines. After studying its characteristics, it is found that the solid particle size of the calcium aluminate casting residue is 5 - 50 mm, and its chemical composition by mass percentage includes: CaO is 55 - 60%, Al2O3 is 25 - 30%, (FeO + MnO) is ≤2%, MgO is ≤5%, SiO2 is ≤3%, metallic Fe is ≤2%, S is ≤0.3%, and other inevitable impurity components. Obviously, the calcium aluminate casting residue belongs to metallurgical clinker, and its melting point is relatively low. After participating in slag making, it can increase the Al2O3 component in the slag system, increase the proportion of low melting point phases in the slag, and accelerate the slag making speed during refining. Therefore, this application uses calcium aluminate casting residue to replace the original fluorite slag making material to play a fluxing role. More importantly, the erosion of the calcium aluminate casting residue on the ladle refractories is much lower than that of fluorite, which is beneficial to reducing the content of composite inclusions MgO in steel and realizing the plasticization of inclusions.

[0016] Through actual working condition tests, it is found that the addition amounts of calcium aluminate casting residue and lime are determined by the oxygen content in the molten steel during tapping. Specifically, when the oxygen content ≤ 0.02%, 1 kg / t < the weight of calcium aluminate casting residue ≤ 1.5 kg / t, and 0.5 kg / t < the weight of lime ≤ 1 kg / t; when 0.02% < oxygen content ≤ 0.04%, 1.5 kg / t < the weight of calcium aluminate casting residue ≤ 2 kg / t, and 1 kg / t < the weight of lime ≤ 2 kg / t; when 0.04% < oxygen content ≤ 0.06%, 2 kg / t < calcium aluminate casting residue ≤ 2.5 kg / t, and 2 kg / t < the weight of lime ≤ 3 kg / t.

[0017] There is also a particularity regarding the oxygen content. If the oxygen content > 0.06%, continuing to smelt according to the process of this steel type may face many difficulties, such as a large number of inclusions generated by molten steel deoxidation and unstable control of the T.O content of molten steel due to continuous reaction between slag and steel, which are not conducive to the control of the cleanliness of stranded steel, with a low refining rate and poor stability of the finished product quality. Therefore, it is necessary to refine other steel types.

[0018] After limiting the addition amounts of calcium aluminate casting residue and lime, the addition amounts of other materials are further limited. For example, ferrosilicon is 0.5 - 1 kg / t, silicomanganese is 8 - 10 kg / t, high-carbon ferrochrome is 2.5 - 3.5 kg / t, and low-nitrogen carbon powder is 3 - 6 kg / t.

[0019] Step S3, LF refining. After the ladle enters the station, bottom blowing is started. The duration of bottom blowing is 5 - 10 min, and the flow rate of argon for bottom blowing is set at 2.5 - 4.5 NL / (min·t). Then, electrodes are inserted into the ladle and energized to raise the temperature, so as to precisely adjust the molten steel temperature to meet the requirements of subsequent processes. Some slag formers, such as lime and calcium carbide, are continuously added to adjust the content of each phase composition in the refining slag. With a suitable refining slag, sulfur in the molten steel is further removed, and inclusions are adsorbed to improve the purity of the molten steel. Generally, the addition amount of lime is added according to the actual working conditions, and the addition amount is 0.5 - 1 kg / t, and the addition amount of calcium carbide is 0.5 - 0.8 kg / t. According to the actual working conditions, ferrosilicon, silicomanganese, and carbon powder are added to adjust the composition of the molten steel to the target composition. After the composition of the molten steel reaches the target composition, soft stirring is started; here, the duration of soft stirring is 8 - 12 min, and the flow rate of argon for bottom blowing is set at 0.5 - 0.9 NL / (min·t). After the soft stirring is completed, carbonized rice husk is added on the slag surface to play a role in heat preservation and preventing secondary oxidation of the molten steel, and then it is adjusted to continuous casting for waiting for pouring.

[0020] This involves another innovation point of this application. Controlling the basicity of the refining end slag to 1.6 - 2.0 can reduce the melting point of the refining slag, increase the slag formation speed of the refining slag, and still retain a certain desulfurization ability to meet the desulfurization requirements of the molten steel. Analyzing from the aspect of inclusion control, controlling the basicity of the refining slag, reducing the CaO content in the slag, and increasing the Al2O3 content in the slag can reduce the activity of CaO and increase the activity of Al2O3 in the slag-metal reaction system, which is beneficial to reducing the generation of Al2O3 inclusions in the steel slag; it is also beneficial to reducing the CaO content in the complex inclusions and appropriately increasing the Al2O3 content to plasticize large-sized complex inclusions. Finally, in the refining end slag, the components by mass percentage include: the MgO content ≤ 5%, the content of (Ca2Al2SiO7 + CaAl2SiO6) is 20 - 30%, and the content of (FeO + MnO) ≤ 2%.

[0021] Step S4, continuous casting. A 150×150 mm square billet continuous caster is used for full protection casting to form steel, preventing the molten steel from contacting with air during pouring and oxidizing, and ensuring the quality of the cast billet. The superheat temperature of the molten steel is set at 10 - 30 °C. A suitable superheat ensures good fluidity of the molten steel and at the same time avoids defects in the cast billet. The drawing speed of the square billet is 2.4 - 2.6 m / min, and the cooling water ratio is 0.24 - 0.26 L / kg. The drawing speed and the cooling water volume cooperate with each other to control the solidification process of the cast billet and ensure the internal quality and appearance quality of the cast billet.

[0022] Finally, the high-purity stranded wire steel (taking SWRH82B as an example) obtained by the above preparation method mainly includes the following components by mass percentage: C is 0.81-0.84%, Si is 0.18-0.22%, Mn is 0.78-0.82%, P is ≤0.01%, S is ≤0.015%, Cr is 0.16-0.20%, Alt ≤0.003%, T.O ≤0.0015%, and Fe and other inevitable impurity components. By controlling the total aluminum and total oxygen content in the components, the purpose of improving product performance and reducing production costs is achieved.

[0023] Finally, based on the high-purity stranded wire steel preparation method, continue with step S5, rolling. The heating furnace heats the steel to the preset rolling temperature, and the steel is rolled to the preset specifications through rough rolling and finish rolling in sequence, and is made into stranded wire rod with a specification of Φ5-10mm by segmented controlled cooling.

[0024] In order to verify that the wire rod prepared by the high-purity stranded wire steel preparation method provided in this application can meet the goals set in this application, Example 1, Example 2, and Example 3 are given below, and Comparative Example 1 and Comparative Example 2 are also given to prove the superiority of this application. Example

[0025] Example 1:

[0026] The present invention provides a high-purity stranded wire steel and its preparation method. By weight percentage, in the main components of the high-purity stranded wire steel SWRH82B, C is 0.81-0.84%, Si is 0.18-0.22%, Mn is 0.78-0.82%, P is ≤0.01%, S is ≤0.015%, Cr is 0.16-0.20%, and Fe and other inevitable impurity components. Its characteristic lies in the following element contents: Alt is ≤0.003%, and T.O is ≤0.0015%.

[0027] Its preparation method includes the following steps: The smelting process includes: blast furnace smelting-converter smelting-LF refining-continuous casting and pouring-rolling. Specifically: Blast furnace smelting: Select low-phosphorus iron ore to obtain hot metal in the blast furnace. After the hot metal is tapped and enters the ladle, it is covered for heat preservation and transported to the converter for smelting. The temperature of the hot metal in the ladle before entering the furnace is 1383°C. The hot metal composition by mass percentage includes: C is 4.42%, Si is 0.35%, Mn is 0.26%, P is 0.098%, S is 0.037%, and Fe and other inevitable impurity components.

[0028] Converter Smelting: The total charged amount of steel materials in the converter is 135 t, with a scrap ratio of 24.4%. Among them, there are 102 t of hot metal and 33 t of scrap. High-low-low lance position blowing is adopted. The basicity of the slag at the end of blowing is 3.2, the molten steel temperature is 1648 °C, the tapping amount is 120 t. By mass percentage, the chemical composition of the molten steel is C: 0.120%, O: 0.0332%, S: 0.018%. Bottom blowing of the ladle is started during tapping, with a bottom blowing flow rate of 5 NL / (min·t) and a continuous bottom blowing time of 9 min. After 1 / 3 of the molten steel is tapped, 92 kg of ferrosilicon, 1031 kg of silicomanganese, 312 kg of high-carbon ferrochrome, 223 kg of calcium aluminate casting residue, 187 kg of lime, and 637 kg of low-nitrogen carbon powder are added in sequence. The amount of slag flowing into the ladle during tapping is less than 200 kg.

[0029] LF Refining: After the ladle enters the station, bottom blowing is started and the electrode is inserted to energize for temperature rise. The argon flow rate for bottom blowing stirring during energizing and feeding is 2.5 NL / (min·t), and it is 4.2 NL / (min·t) during mixing and desulfurization; 45 kg of lime and 60 kg of calcium carbide are added, and after energizing for 5.1 minutes, the fluidity of the refining slag is good. The measured basicity of the refining slag is 1.8, the MgO content is 4.2%, the content of (Ca2Al2SiO7 + CaAl2SiO6) is 29%, and the content of (FeO + MnO) is 1.7%. 30 kg of ferrosilicon, 25 kg of silicomanganese, and 40 kg of carbon powder are added. After mixing, a sample is taken, and the chemical composition of the molten steel is C: 0.823%, Si: 0.192%, Mn: 0.806%, P: 0.0094%, S: 0.0041%, Cr: 0.185%, as well as Fe and other inevitable impurity components. After the chemical composition of the molten steel meets the standards, soft stirring is started, and the soft stirring lasts for 10 min with an argon flow rate of 0.7 NL / (min·t). After the soft stirring ends, 5 packages of carbonized rice husk are added on the slag surface, and then it is adjusted to wait for continuous casting for pouring.

[0030] Continuous Casting: A 150×150 mm square billet continuous caster is used for full-process protected casting. The superheat of the molten steel is 25 °C, the drawing speed of the square billet is 2.5 m / min, the cooling water ratio is 0.25 L / kg. Sampling in the tundish shows that the Alt in the molten steel is 0.0019%, the T.O is 0.0012%, and the proportion of plastic inclusions in the composite inclusions detected in the billet sample is 75%.

[0031] Rolling: After being heated in a heating furnace - rough rolling - finish rolling - section controlled cooling, it is made into a steel strand wire rod with a specification of Φ5.5 mm. Among them, the starting rolling temperature of rough rolling is 1060 °C, and the inlet temperature of finish rolling is 965 °C.

[0032] Example 2:

[0033] The present invention provides a high-cleanliness stranded wire steel and a preparation method thereof. By weight percentage, in the main components of the high-cleanliness stranded wire steel SWRH82B, C is 0.81 - 0.84%, Si is 0.18 - 0.22%, Mn is 0.78 - 0.82%, P is ≤0.01%, S is ≤0.015%, Cr is 0.16 - 0.20%, and Fe and other inevitable impurity components. Its characteristic lies in the following element contents: Alt is ≤0.003%, and T.O is ≤0.0015%.

[0034] Its preparation method includes the following steps: The smelting process includes: blast furnace smelting - converter smelting - LF refining - continuous casting - rolling. Specifically: Blast furnace smelting: Select low-phosphorus iron ore to obtain hot metal in the blast furnace. After the hot metal is tapped and enters the ladle, it is covered for heat preservation and transported to the converter for smelting. Before entering the furnace, the temperature of the hot metal in the ladle is 1387°C. The hot metal composition by mass percentage includes: C is 4.55%, Si is 0.37%, Mn is 0.25%, P is 0.095%, S is 0.041%, and Fe and other inevitable impurity components.

[0035] Converter smelting: The total charged amount of steel materials in the converter is 135t, and the scrap ratio is 25.2%, including 101t of hot metal and 34t of scrap. High - low - low lance position blowing is adopted. The basicity of the slag at the end of blowing is 3.1, and the temperature of the molten steel is 1640°C. The tapping amount is 120t. The molten steel composition by mass percentage is: C is 0.140%, O is 0.0224%, and S is 0.0176%. Bottom blowing of the ladle is started during tapping, and the bottom blowing flow rate is 5 NL / (min·t), and the bottom blowing time lasts for 8 minutes. After 1 / 3 of the molten steel is tapped, 98kg of ferrosilicon, 1019kg of silicomanganese, 307kg of high-carbon ferrochrome, 184kg of calcium aluminate casting residue, 129kg of lime, and 451kg of low-nitrogen carbon powder are added in sequence. The amount of slag falling during tapping is less than 200kg.

[0036] LF Refining: After the ladle enters the station, the bottom blowing is started and the electrode is inserted to energize for heating up. The argon flow rate for bottom blowing stirring during energizing and feeding is 2.5 NL / (min·t), and it is 4.2 NL / (min·t) during mixing and desulfurization; 62 kg of lime and 60 kg of calcium carbide are added, energized for 4.8 minutes, the refining slag has good fluidity, the basicity of the refining slag is measured to be 1.7, the MgO content is 4.4%, the content of (Ca2Al2SiO7 + CaAl2SiO6) is 26%, and the content of (FeO + MnO) is 1.8%. 33 kg of ferrosilicon, 29 kg of silicomanganese, and 35 kg of carbon powder are added. After mixing, the chemical composition of the molten steel is sampled and obtained as C: 0.827%, Si: 0.199%, Mn: 0.794%, P: 0.0088%, S: 0.0062%, Cr: 0.171%, as well as Fe and other inevitable impurity components. After the chemical composition of the molten steel meets the standards, soft stirring is started, and the soft stirring lasts for 10 min with an argon flow rate of 0.7 NL / (min·t). After the soft stirring is completed, 5 packages of carbonized rice husk are added on the slag surface, and then it is adjusted to continuous casting for waiting for pouring.

[0037] Continuous Casting: The whole process of protective casting is carried out using a 150×150 mm square billet continuous caster. The superheat of the molten steel is 27 °C, the pulling speed of the square billet is 2.5 m / min, the cooling water ratio is 0.25 L / kg, and the Alt in the molten steel is measured to be 0.0016% and the T.O is 0.0009% by sampling in the tundish. The proportion of plastic inclusions in the composite inclusions detected in the billet sample is 71%.

[0038] Rolling: After being heated in a heating furnace - rough rolling - finish rolling - sectional controlled cooling, it is made into a steel strand wire rod with a specification of Φ5.5 mm. The starting rolling temperature of the rough rolling is 1060 °C, and the inlet temperature of the finish rolling is 965 °C.

[0039] Example 3:

[0040] The present invention provides a high - cleanliness stranded wire steel and its preparation method. By weight percentage, in the main components of the high - cleanliness stranded wire steel SWRH82B, C is 0.81 - 0.84%, Si is 0.18 - 0.22%, Mn is 0.78 - 0.82%, P is ≤0.01%, S is ≤0.015%, Cr is 0.16 - 0.20%, as well as Fe and other inevitable impurity components. Its characteristic lies in the following element contents: Alt is ≤0.003%, and T.O is ≤0.0015%.

[0041] Its preparation method includes the following steps: The smelting process includes: blast furnace smelting - converter smelting - LF refining - continuous casting - rolling, specifically: Blast furnace smelting: Low-phosphorus iron ore is selected for smelting in the blast furnace to obtain hot metal. After the hot metal is tapped and enters the ladle, it is covered to keep warm and transported to the converter for smelting. Before entering the furnace, the temperature of the hot metal in the ladle is 1362 °C. The hot metal composition by mass percentage includes: C is 4.37%, Si is 0.38%, Mn is 0.29%, P is 0.093%, S is 0.034%, and Fe and other inevitable impurity components.

[0042] Converter smelting: The total charge of steel materials in the converter is 135 t, and the scrap ratio is 25.9%. Among them, 100 t of hot metal and 35 t of scrap are used. High-low-low lance position blowing is adopted. The basicity of the slag at the end of blowing is 3.0, the temperature of the molten steel is 1632 °C, and the tapping amount is 120 t. The molten steel composition by mass percentage is: C is 0.077%, O is 0.0417%, and S is 0.0171%. Bottom blowing of the ladle is started during tapping, and the bottom blowing flow rate is 5 NL / (min·t), and the bottom blowing time lasts for 10 min. After 1 / 3 of the molten steel is tapped, 99 kg of ferrosilicon, 1001 kg of silicomanganese, 300 kg of high-carbon ferrochrome, 289 kg of calcium aluminate cast residue, 240 kg of lime, and 688 kg of low-nitrogen carbon powder are added in sequence. The amount of slag falling during tapping is less than 200 kg.

[0043] LF refining: After the ladle enters the station, bottom blowing is started and the electrode is inserted to energize and raise the temperature. The argon flow rate for bottom blowing stirring during energization and feeding is 2.5 NL / (min·t), and it is 4.2 NL / (min·t) during mixing and desulfurization; 27 kg of lime and 60 kg of calcium carbide are added, and the power is supplied for 4.9 minutes. The fluidity of the refining slag is good. The basicity of the refining slag is measured to be 1.9, the MgO content is 4.1%, the content of (Ca2Al2SiO7 + CaAl2SiO6) is 29%, and the content of (FeO + MnO) is 1.6%. 33 kg of ferrosilicon, 27 kg of silicomanganese, and 45 kg of carbon powder are added. After mixing, a sample is taken, and the molten steel composition is C is 0.817%, Si is 0.188%, Mn is 0.798%, P is 0.0092%, S is 0.002%, Cr is 0.181%, and Fe and other inevitable impurity components. After the molten steel composition meets the standards, soft stirring is started, and the soft stirring lasts for 10 min, and the argon flow rate is 0.7 NL / (min·t). After the soft stirring is over, 5 packages of carbonized rice husks are added on the slag surface, and then it is adjusted to continuous casting and waiting for pouring.

[0044] Continuous casting: A 150×150 mm square billet continuous caster is used for full-process protected casting. The superheat of the molten steel is 24 °C, the drawing speed of the square billet is 2.5 m / min, the cooling water ratio is 0.25 L / kg. Sampling in the tundish shows that Alt in the molten steel is 0.0014%, T.O is 0.0011%, and the proportion of plastic inclusions in the composite inclusions detected in the billet sample is 79%.

[0045] Rolling: After heating in a heating furnace - rough rolling - finish rolling - sectional controlled cooling, steel wire rod coils with a specification of Φ5.5mm are produced. Among them, the rough rolling starting temperature is 1060°C, and the finish rolling inlet temperature is 965°C.

[0046] Example 4:

[0047] The present invention provides a high cleanliness stranded wire steel and its preparation method. By weight percentage, in the main components of the high cleanliness stranded wire steel SWRH82B, C is 0.81 - 0.84%, Si is 0.18 - 0.22%, Mn is 0.78 - 0.82%, P is ≤0.01%, S is ≤0.015%, Cr is 0.16 - 0.20%, and Fe and other inevitable impurity components. Its characteristic lies in the following element contents: Alt is ≤0.003%, and T.O is ≤0.0015%.

[0048] Its preparation method includes the following steps: The smelting process includes: blast furnace smelting - converter smelting - LF refining - continuous casting - rolling. Specifically: Blast furnace smelting: Low - phosphorus iron ore is selected for smelting in the blast furnace to obtain hot metal. After the hot metal is tapped and put into the ladle, it is covered for heat preservation and transported to the converter for smelting. Before entering the furnace, the temperature of the hot metal in the ladle is 1396°C. The hot metal composition by mass percentage includes: C is 4.61%, Si is 0.37%, Mn is 0.21%, P is 0.095%, S is 0.044%, and Fe and other inevitable impurity components.

[0049] Converter smelting: The total charge of the converter steelmaking materials is 135t, and the scrap ratio is 24.4%. Among them, 102t of hot metal and 33t of scrap are used. High - low - low lance position blowing is adopted. The basicity of the slag at the end of blowing is 3.1, and the temperature of the molten steel is 1644°C. The tapping amount is 120t. The molten steel composition by mass percentage is: C is 0.164%, O is 0.0188%, and S is 0.017%. Bottom blowing of the ladle is started during tapping, and the bottom blowing flow rate is 5 NL / (min·t), and the bottom blowing time lasts for 8 minutes. After 1 / 3 of the molten steel is tapped, 99kg of ferrosilicon, 1011kg of silicomanganese, 322kg of high - carbon ferrochrome, 148kg of calcium aluminate casting residue, 84kg of lime, and 594kg of low - nitrogen carbon powder are added in sequence. The amount of slag falling during tapping is less than 200kg.

[0050] LF refining: After the ladle enters the station, the bottom blowing is started and the electrode is inserted to energize for heating up. The argon flow rate for bottom blowing stirring during energizing and feeding is 2.5 NL / (min·t), and 4.2 NL / (min·t) for mixing and desulfurization; 22 kg of lime and 60 kg of calcium carbide are added, and the power is on for 4.5 minutes. The refining slag has good fluidity. The alkalinity of the refining slag is measured to be 1.6, the MgO content is 4.7%, the content of (Ca2Al2SiO7 + CaAl2SiO6) is 25%, and the content of (FeO + MnO) is 1.6%. 30 kg of ferrosilicon, 22 kg of silicomanganese, and 35 kg of carbon powder are added. After mixing, the composition of the molten steel is sampled, and C is 0.831%, Si is 0.197%, Mn is 0.811%, P is 0.0092%, S is 0.004%, Cr is 0.181%, as well as Fe and other inevitable impurity components. After the composition of the molten steel meets the standard, soft stirring is started, and the soft stirring lasts for 10 min with an argon flow rate of 0.7 NL / (min·t). After the soft stirring ends, 5 packages of carbonized rice husk are added to the slag surface, and then it is adjusted to continuous casting for waiting for pouring.

[0051] Continuous casting: The whole process of protective casting is carried out using a 150×150 mm square billet continuous caster. The superheat of the molten steel is 28 °C, the drawing speed of the square billet is 2.5 m / min, the cooling water ratio is 0.25 L / kg, and the Alt in the molten steel is measured to be 0.0017% and T.O is 0.0008% by sampling in the tundish. The proportion of plastic inclusions in the composite inclusions detected in the billet sample is 74%.

[0052] Rolling: After being heated in a heating furnace - rough rolling - finish rolling - sectional controlled cooling, it is made into a steel strand wire rod with a specification of Φ5.5 mm. The starting rolling temperature of the rough rolling is 1060 °C, and the inlet temperature of the finish rolling is 965 °C.

[0053] Comparative example 1: The present invention provides a high - cleanliness stranded wire steel and its preparation method. By weight percentage, the main components of the high - cleanliness stranded wire steel SWRH82B are C 0.81 - 0.84%, Si 0.18 - 0.22%, Mn 0.78 - 0.82%, P ≤0.01%, S ≤0.015%, Cr 0.16 - 0.20%, as well as Fe and other inevitable impurity components. Its characteristic lies in the following element contents: Alt ≤0.003% and T.O ≤0.0015%.

[0054] Its preparation method includes the following steps: The smelting process includes: blast furnace smelting - converter smelting - LF refining - continuous casting - rolling. Specifically: Blast furnace smelting: Low-phosphorus iron ore is selected for smelting in the blast furnace to obtain hot metal. After the hot metal is tapped and enters the ladle, it is covered to keep warm and transported to the converter for smelting. The temperature of the hot metal in the ladle before entering the furnace is 1399 °C. The hot metal composition by mass percentage includes: C is 4.67%, Si is 0.33%, Mn is 0.27%, P is 0.094%, S is 0.038%, and Fe and other inevitable impurity components.

[0055] Converter smelting: The total charge of steel materials in the converter is 135 t, and the scrap ratio is 25.9%, including 100 t of hot metal and 35 t of scrap. High-low-low lance position blowing is adopted. The basicity of the slag at the end of blowing is 3.1, the temperature of the molten steel is 1637 °C, and the tapping amount is 120 t. The molten steel composition by mass percentage is: C is 0.110%, O is 0.0384%, and S is 0.017%. Bottom blowing of the ladle is started during tapping, and the bottom blowing flow rate is 5 NL / (min·t), and the bottom blowing time lasts for 8 min. After 1 / 3 of the molten steel is tapped, 106 kg of low-aluminum ferrosilicon, 1082 kg of silicomanganese, 307 kg of low-aluminum ferrochromium, 262 kg of lime, and 637 kg of low-nitrogen carbon powder are added in sequence. The slag volume during tapping is less than 200 kg.

[0056] LF refining: After the ladle enters the station, bottom blowing is started and the electrode is inserted to energize for temperature rise. The argon flow rate for bottom blowing stirring during energizing and feeding is 2.5 NL / (min·t), and it is 4.2 NL / (min·t) during mixing and desulfurization; 144 kg of lime, 177 kg of fluorite, and 60 kg of calcium carbide are added. After energizing for 5.6 minutes, the fluidity of the refining slag is good. The basicity of the measured refining slag is 2.4, the MgO content is 7.1%, and the main phases are high-melting-point phases such as Ca2SiO4, Ca3Mg(SiO4)2, and MgO. The content of (FeO + MnO) is 1.7%. 33 kg of ferrosilicon, 21 kg of silicomanganese, and 35 kg of carbon powder are added. After mixing, a sample is taken and the molten steel composition is C is 0.811%, Si is 0.19%, Mn is 0.81%, P is 0.0088%, S is 0.0065%, Cr is 0.177%, and Fe and other inevitable impurity components. After the molten steel composition meets the standards, soft stirring is started, and the soft stirring lasts for 10 min, and the argon flow rate is 0.7 NL / (min·t). After the soft stirring ends, 5 packages of carbonized rice husks are added on the slag surface, and then it is adjusted to continuous casting and waiting for pouring.

[0057] Continuous casting: A 150×150 mm square billet continuous casting machine is used for full-process protected casting. The superheat of the molten steel is 25 °C, the pulling speed of the square billet is 2.5 m / min, the cooling water ratio is 0.25 L / kg. Sampling in the tundish shows that the Alt in the molten steel is 0.0022% and the T.O is 0.0025%. In the cast billet sample, the proportion of plastic inclusions in the composite inclusions is 12%. The proportion of hard inclusions in the cast billet is relatively high, and the product is downgraded to ordinary stranded wire steel.

[0058] Comparative Example 2: The present invention provides a high-cleanliness stranded wire steel and a preparation method thereof. By weight percentage, in the main components of the high-cleanliness stranded wire steel SWRH82B, C is 0.81 - 0.84%, Si is 0.18 - 0.22%, Mn is 0.78 - 0.82%, P is ≤0.01%, S is ≤0.015%, Cr is 0.16 - 0.20%, and Fe and other inevitable impurity components. Its characteristic lies in the following element contents: Alt is ≤0.003%, and T.O is ≤0.0015%.

[0059] Its preparation method includes the following steps: The smelting process includes: blast furnace smelting - converter smelting - LF refining - continuous casting - rolling. Specifically: Blast furnace smelting: Low-phosphorus iron ore is selected for smelting in the blast furnace to obtain molten iron. After the molten iron is tapped and enters the ladle, it is covered for heat preservation and transported to the converter for smelting. The temperature of the molten iron in the ladle before entering the furnace is 1374°C. The composition of the molten iron by mass percentage includes: C is 4.45%, Si is 0.31%, Mn is 0.29%, P is 0.096%, S is 0.042%, and Fe and other inevitable impurity components.

[0060] Converter smelting: The total charge of the converter steelmaking materials is 135t, and the scrap ratio is 24.4%. Among them, 102t of molten iron and 33t of scrap steel. High - low - low lance position blowing is adopted. The basicity of the slag at the end of blowing is 3.1, and the temperature of the molten steel is 1642°C. The tapping amount is 120t. The composition of the molten steel by mass percentage is: C is 0.096%, O is 0.0384%, and S is 0.016%. The bottom blowing of the ladle is started during tapping, and the bottom blowing flow rate is 5 NL / (min·t), and the bottom blowing time lasts for 10 minutes. After 1 / 3 of the molten steel is tapped, 112kg of low-aluminum ferrosilicon, 1044kg of silicomanganese, 316kg of low-aluminum ferrochromium, 282kg of lime, and 644kg of low-nitrogen carbon powder are added in sequence. The slag volume during tapping is less than 200kg.

[0061] LF refining: After the ladle enters the station, the bottom blowing is started and the electrodes are inserted to energize for heating up. The argon flow rate for bottom blowing stirring during energization and feeding is 2.5 NL / (min·t), and it is 4.2 NL / (min·t) during mixing and desulfurization; 170 kg of lime, 255 kg of fluorite, and 60 kg of calcium carbide are added. After energizing for 5.4 minutes, the fluidity of the refining slag is good. The basicity of the refining slag is measured to be 2.4, the MgO content is 7.6%, the main phases are high melting point phases such as Ca2SiO4, Ca3Mg(SiO4)2, and MgO, and the (FeO + MnO) content is 1.7%. 31 kg of ferrosilicon, 28 kg of silicomanganese, and 45 kg of carbon powder are added. After mixing, a sample is taken, and the chemical composition of the molten steel is C 0.821%, Si 0.184%, Mn 0.812%, P 0.0092%, S 0.0007%, Cr 0.181%, as well as Fe and other inevitable impurity components. After the chemical composition of the molten steel meets the standards, soft stirring is started, and the soft stirring lasts for 10 min with an argon flow rate of 0.7 NL / (min·t). After the soft stirring ends, 5 packages of carbonized rice husk are added to the slag surface, and then it is adjusted to continuous casting for waiting for pouring.

[0062] Continuous casting: The whole process of protected casting is carried out using a 150×150 mm square billet continuous caster. The superheat of the molten steel is 25°C, the drawing speed of the square billet is 2.5 m / min, the specific cooling water volume is 0.25 L / kg, and the Alt in the molten steel is measured to be 0.0021% and the T.O is 0.0027% by sampling in the tundish. The proportion of plastic inclusions in the composite inclusions detected in the billet sample is 16%. The proportion of hard inclusions in the billet is relatively high, and the product is downgraded to ordinary stranded wire steel.

[0063] For intuitive comparison, the above-mentioned Example 1, Example 2, and Example 3, Comparative Example 1, and Comparative Example 2 of the present application are integrated in Table 1.

[0064] Table 1 Technical index application data of the present application and integrated data of comparative examples Item Calcium aluminate casting residue Lime Fluorite Hot metal S Final product S Desulfurization rate Slag melting time Continuous casting Alt Continuous casting T.O Proportion of plastic inclusions Unit kg kg kg % % % min % % % Example 1 223 232 0 0.037 0.0041 89 5.1 0.0019 0.0012 75 Example 2 184 191 0 0.041 0.0062 85 4.8 0.0016 0.0009 71 Example 3 289 267 0 0.034 0.002 94 4.9 0.0014 0.0011 79 Example 4 148 106 0 0.044 0.004 91 4.5 0.0017 0.0008 74 Comparative example 1 0 406 177 0.038 0.0065 83 5.6 0.0022 0.0025 12 Comparative example 2 0 452 255 0.042 0.007 84 5.4 0.0021 0.0027 16 In summary, the method for preparing high cleanliness stranded wire steel provided by the present application, the design and application of the refining slag system for stranded wire steel and the precise control method can achieve the target effects such as rapid slag melting of the refining slag, stable desulfurization of the molten steel, reduction of ladle refractory erosion, precise modification and reduction of the amount of Alt and inclusions in the steel, and ultimately improve the processing performance and mechanical properties of the stranded wire steel. In addition, in the present application, the recycled calcium aluminate casting residue is used to replace the use of fluorite, which has certain benefits in reducing the smelting cost, resource utilization of solid waste, and environmental protection.

[0065] Those skilled in the art can understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as the general understanding of those of ordinary skill in the art to which this application belongs. It should also be understood that terms such as those defined in a general dictionary should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted with an idealized or overly formal meaning unless defined as such here.

[0066] The meaning of "and / or" described in this application refers to the situation where each exists alone or both exist simultaneously.

[0067] The meaning of "connection" described in this application can be a direct connection between components or an indirect connection between components through other components.

[0068] Taking the above-mentioned ideal embodiments of the present invention as inspiration, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for preparing high-cleanliness stranded wire steel, characterized in that: The following steps are involved: Step S1, blast furnace smelting, smelting low-phosphorus iron ore in a blast furnace to obtain molten iron, the molten iron enters an iron ladle, the molten iron temperature in the iron ladle before being transferred to the converter is ≥1360°C, and the molten iron formed by smelting includes, by mass percentage, the following components: C is 4.10-4.80%, Si is 0.20-0.60%, Mn is ≤0.35%, P is ≤0.10%, S is ≤0.05%, and Fe and other inevitable impurity components; Step S2, smelting in a converter, adding scrap steel, adopting high-low-low gun position for blowing, the slag basicity at the end of blowing is 2.8-3.3, adding ferrosilicon, silicomanganese, high carbon ferrochrome, calcium aluminate casting slag, lime and low nitrogen carbon powder into the ladle in sequence during the steel tapping process, and opening the ladle bottom blowing throughout the steel tapping process; the components in the molten steel in the tapping process include: C is 0.10-0.50%, O is ≤0.06%, and S is ≤0.03% according to mass percentage; The calcium aluminate casting slag is obtained by recycling, and the amount of calcium aluminate casting slag and lime added is determined by the oxygen content in the steel water. Specifically, When the oxygen content is ≤0.02%, add 1kg / t<the weight of calcium aluminate casting slag ≤1.5kg / t, add 0.5kg / t<the weight of lime ≤1kg / t; When the oxygen content is 0.02%<≤0.04%, add 1.5kg / t<the weight of calcium aluminate casting slag ≤2kg / t, and add 1kg / t<the weight of lime ≤2kg / t; When the oxygen content is 0.04% < ≤ 0.06%, add 2kg / t < calcium aluminate casting slag ≤ 2.5kg / t, add 2kg / t < lime weight ≤ 3kg / t; Step S3, LF refining, after the ladle enters the station, the bottom blowing is started and the electrode is inserted into the ladle to energize and heat it, lime and calcium carbide as slag-forming agents are added, ferrosilicon, silicon manganese and carbon powder are added to adjust the composition of the molten steel to the target composition, and soft stirring is started after the composition of the molten steel reaches the target composition; in the slag at the end of refining, the components in terms of mass percentage include: MgO content ≤5%, (Ca2Al2SiO7+CaAl2SiO6) content of 20-30%, (FeO+MnO) content ≤2%; Step S4, continuous casting, using a 150×150mm square billet continuous casting machine to cast steel with full protection, setting the molten steel superheat temperature to 10-30°C, the billet pulling speed to 2.4-2.6m / min, and the cooling water volume to 0.24-0.26L / kg.

2. The method for preparing high-cleanliness stranded wire steel according to claim 1, characterized in that: In step S1, molten iron obtained from blast furnace smelting enters an iron ladle and is covered to keep it warm.

3. The method for preparing high-cleanliness stranded wire steel according to claim 1, characterized in that: In step S2, the total loading amount of steel material in the converter is 135±2t, the ratio of scrap steel added is 20-25%; the tapping temperature of molten steel is 1620-1660°C, and the amount of slag at tapping is ≤200kg.

4. The method for preparing high-cleanliness stranded wire steel according to claim 1, characterized in that: In step S2, during the steel tapping process, 0.5-1 kg / t of ferrosilicon, 8-10 kg / t of silicon manganese, 2.5-3.5 kg / t of high carbon ferrochrome, and 3-6 kg / t of low nitrogen carbon powder are added to the ladle.

5. The method for preparing high-cleanliness stranded wire steel according to claim 1, characterized in that: In step S2, the solid particle size of the calcium aluminate casting slag is 5-50 mm, and its chemical composition includes, by mass percentage: CaO is 55-60%, Al2O3 is 25-30%, (FeO+MnO) is ≤2%, MgO is ≤5%, SiO2 is ≤3%, metal Fe is ≤2%, S is ≤0.3% and other inevitable impurity components.

6. The method for preparing high-cleanliness stranded wire steel according to claim 1, characterized in that: In step S2, the ladle bottom blowing is turned on throughout the steel tapping process for a duration of 5-10 minutes, and the bottom blowing argon flow rate is set to 4-5NL / (min·t).

7. The method for preparing high-cleanliness stranded wire steel according to claim 1, characterized in that: In step S3, the slag-forming agent is supplemented with lime in an amount of 0.5-1 kg / t and calcium carbide in an amount of 0.5-0.8 kg / t; the basicity of the slag at the end of refining is 1.6-2.

0.

8. The method for preparing high-cleanliness stranded wire steel according to claim 1, characterized in that: In step S3, after the ladle enters the station, the bottom blowing is started for 5-10 minutes, and the bottom blowing argon flow rate is set to 2.5-4.5NL / (min·t); The duration of soft stirring is 8-12 minutes, and the bottom blowing argon flow rate is set to 0.5-0.9 NL / (min·t).

9. The stranded wire steel obtained by the method for preparing high-cleanliness stranded wire steel according to any one of claims 1 to 8, characterized in that: Calculated by mass percentage, the main components include: C 0.81-0.84%, Si 0.18-0.22%, Mn 0.78-0.82%, P ≤0.01%, S ≤0.015%, Cr 0.16-0.20%, Alt ≤0.003%, TO ≤0.0015% and Fe and other inevitable impurity components.

10. A method for preparing a wire rod, characterized in that: Based on the method for preparing high-cleanliness stranded wire steel as described in claim 1, continue with step S5, rolling, the heating furnace heats the steel to a preset rolling temperature, and sequentially rolls the steel to preset specifications through rough rolling and finish rolling, and uses segmented controlled cooling to form steel stranded wire rods with a specification of Φ5-10mm.