A toughened steel core alloy material for overhead conductors and a method of making the same

Abstract

The application discloses a toughened steel core alloy material for overhead conductor, which comprises the following chemical elements in percentage by mass: C: 0.75% to 0.85%, Mn: 0.40% to 0.90%, Si: 0.15% to 0.25%, P: less than or equal to 0.005%, S: less than or equal to 0.005%, reinforcing phase elements Ni: 0.20% to 0.60%, and Al: 0.10% to 0.30%, and the balance is Fe and inevitable impurity elements. The content of Ni, Al and alloy elements is optimized to make Ni and Al fully form a uniformly dispersed intermetallic compound NiAl phase, the high coherence structure of the NiAl phase and the iron matrix is utilized to realize the synergistic improvement of the strength and toughness of the alloy material, meanwhile, the irreversible hydrogen trap effect of the NiAl phase is exerted to reduce the hydrogen embrittlement sensitivity of the alloy material, and the problem that the strength and plasticity of the existing material are difficult to be considered simultaneously is solved.

Description

Technical Field

[0001] This invention belongs to the technical field of overhead power transmission conductor core technology, specifically relating to a toughened steel core alloy material for overhead conductors and its preparation method. Background Technology

[0002] Overhead transmission lines bear the critical tasks of conducting current and transmitting electrical energy, while also bearing normal operating loads as well as additional loads caused by environmental factors such as icing and strong winds. As the core load-bearing component of the conductor, the mechanical properties of the steel core material determine the conductor's load-bearing capacity, overall tensile strength, anti-sag performance, and service life.

[0003] Currently, high-carbon steel is mostly used for the steel cores of overhead conductors. The existing high-carbon steel core strengthening system is simple. During the smelting, processing and service process, degassing and impurity removal are mostly carried out using a single temperature vacuum treatment, which cannot achieve efficient separation of gas and impurities. This can easily lead to sudden brittle fracture of the steel core, which seriously affects the safety and stability of overhead transmission lines. This results in the problem that carbon steel materials for ultra-strong steel cores have difficulty in balancing strength and plasticity and have high sensitivity to hydrogen embrittlement.

[0004] Accordingly, there is a need in the field for a new toughened steel core conductor alloy material and its preparation method to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to solve the problem that it is difficult to balance the strength and plasticity of high-carbon steel cores used in overhead conductors in the prior art.

[0006] The objective of this invention is achieved through the following technical solution: This invention provides a toughened steel core alloy material for overhead conductors, comprising the following chemical elements by mass percentage: C: 0.75%~0.85%, Mn: 0.40%~0.90%, Si: 0.15%~0.25%, P≤0.005%, S≤0.005%; strengthening phase element Ni: 0.20%~0.60%, Al: 0.10%~0.30%; the balance being Fe and unavoidable impurity elements.

[0007] Preferably, the reinforcing phase element Ni is 0.30%~0.50% and Al is 0.15%~0.25%.

[0008] Preferably, the mass ratio of Ni to Al in the strengthening phase element is 2:1.

[0009] Based on the same inventive concept, this invention also provides a method for preparing the toughened steel core alloy material for overhead conductors, comprising: a smelting process: adding non-strengthening phase elements C, Mn, Si, P, and S raw materials to pretreated molten iron according to the chemical element ratio of the alloy material; after the non-strengthening phase elements melt, adding strengthening phase elements Ni and Al raw materials in batches to obtain molten steel with a preliminary NiAl phase dispersion; a refining process: transferring the molten steel to a refining furnace for high-purity refining and desulfurization treatment to obtain refined molten steel; a degassing and impurity removal process: transferring the refined molten steel to a vacuum furnace and using a two-stage temperature gradient for vacuum degassing and inclusion removal treatment to obtain high-quality molten steel with uniform composition and qualified purity; a casting process: continuously casting the high-quality molten steel and cooling it to room temperature to obtain a steel billet; and a forming process: sequentially hot rolling, heat treatment, and drawing treatment of the steel billet to obtain a single steel core wire.

[0010] Preferably, the smelting process uses an electric arc furnace for smelting at a temperature of 1500℃~1580℃ and a holding time of 20min~30min. The temperature of the molten steel is stabilized at 1520℃~1550℃. The strengthening phase elements Ni and Al are added in two batches. The first batch is 60% of the total mass of the strengthening phase elements Ni and Al, and the stirring time after addition is 8min~10min. The second batch is 40% of the total mass of the strengthening phase elements Ni and Al, and the stirring time continues for 8min~12min, followed by a holding time of 20min~30min.

[0011] Preferably, the pretreated molten iron is prepared by adding CaO-based flux to the molten iron and performing dephosphorization treatment under an oxidizing atmosphere. The molten iron temperature is 1320℃~1390℃ and the stirring speed is 110r / min~160r / min.

[0012] Preferably, the refining process involves transferring the molten steel after smelting into a refining furnace, adding high-purity CaO-Al2O3-based refining slag, controlling the slag basicity to 3.8~4.8, blowing in argon gas and stirring, with a refining stirring speed of 90r / min~130r / min, a refining temperature of 1590℃~1630℃, a refining holding time of 45min~65min, a settling time of 5min~8min after refining, and removing the refining slag to obtain refined molten steel.

[0013] Preferably, the degassing and impurity removal process is carried out under an argon atmosphere, and the two-stage temperature gradient treatment is as follows: The first stage of temperature treatment involves heating the refined molten steel to 1580℃~1650℃, holding it at that temperature for 20min~30min, and controlling the stirring speed at 70r / min~90r / min. The second stage of temperature treatment involves cooling the refined molten steel to 1500℃~1580℃ at a cooling rate of 5℃ / min~8℃ / min, holding it at that temperature for 30min~40min, and adjusting the stirring speed to 40r / min~60r / min.

[0014] Preferably, after the two-stage temperature gradient treatment is completed, the vacuum furnace ends the vacuum state, the stirring speed is controlled at 30 r / min to 50 r / min, and the stirring time is 15 min to 20 min.

[0015] Preferably, the cooling rate is controlled at 5℃ / min to 8℃ / min during the continuous casting process of the casting procedure.

[0016] Preferably, in the forming process, the hot rolling treatment involves heating the steel billet to a hot rolling start temperature of 950℃~1050℃, holding it at the hot rolling temperature for 30min~40min, then hot rolling is performed, and the hot rolling finish temperature is controlled at 820℃~880℃. After rolling, the billet is air-cooled to obtain hot-rolled wire rod.

[0017] Preferably, in the forming process, the heat treatment is to perform isothermal quenching on the hot-rolled wire rod in a lead bath furnace, with the quenching temperature controlled at 500℃~650℃ and the quenching holding time at 60min~90min.

[0018] Preferably, in the forming process, the drawing process involves drawing the hot-rolled wire rod in multiple passes to obtain a steel core single wire, with the total drawing deformation controlled at 60% to 75%, and the deformation per pass controlled not to exceed 15% during the drawing process.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a toughened steel core alloy material for overhead conductors, comprising the following chemical elements by mass percentage: C: 0.75%~0.85%, Mn: 0.40%~0.90%, Si: 0.15%~0.25%, P≤0.005%, S≤0.005%; strengthening phase element Ni: 0.20%~0.60%, Al: 0.10%~0.30%; the balance being Fe and unavoidable impurity elements. By optimizing the content of Ni, Al, and alloying elements to fully form a uniformly dispersed intermetallic compound NiAl phase, the high coherence between the NiAl phase and the iron matrix achieves a synergistic improvement in the strength and toughness of the alloy material. At the same time, the irreversible hydrogen trapping effect of the NiAl phase reduces the hydrogen embrittlement sensitivity of the alloy material, solving the problem of the difficulty in balancing strength and plasticity in existing materials. This alloy material has a tensile strength ≥2200MPa and an elongation ≥3.5%, which can meet the tensile and vibration resistance requirements of harsh working conditions such as ultra-high voltage long-span crossings and heavy icing areas. Detailed Implementation

[0020] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0021] For any experimental steps or conditions not specified in this invention, the conventional experimental steps or conditions described in the literature in this field can be followed.

[0022] This invention provides a toughened steel core alloy material for overhead conductors, comprising the following chemical elements by mass percentage: C: 0.75%~0.85%, Mn: 0.40%~0.90%, Si: 0.15%~0.25%, P≤0.005%, S≤0.005%; strengthening phase element Ni: 0.20%~0.60%, Al: 0.10%~0.30%; the balance being Fe and unavoidable impurity elements.

[0023] In a preferred embodiment, the reinforcing phase elements are Ni: 0.30%~0.50% and Al: 0.15%~0.25%. The mass ratio of Ni to Al in the reinforcing phase elements is 2:1 to ensure the formation of the optimal NiAl reinforcing phase.

[0024] Based on the same inventive concept, the present invention also provides a method for preparing a toughened steel core alloy material for overhead conductors, comprising: S1. Smelting process: According to the chemical element ratio of the alloy material, non-strengthening phase elements C, Mn, Si, P, and S raw materials are added to the pretreated molten iron. After the non-strengthening phase elements melt, strengthening phase elements Ni and Al raw materials are added in batches to obtain molten steel with NiAl phase initially dispersed.

[0025] Specifically, the pretreatment of molten iron involves adding a CaO-based flux and performing dephosphorization treatment under an oxidizing atmosphere. The molten iron temperature is 1320℃~1390℃, and the stirring speed is 110r / min~160r / min. The pretreatment of molten iron ensures that impurities and residual elements are fully separated and removed.

[0026] The smelting process uses an electric arc furnace at a temperature of 1500℃~1580℃ and a holding time of 20min~30min. The temperature of the molten steel is stabilized at 1520℃~1550℃. The strengthening phase elements Ni and Al are added in two batches. The first batch is 60% of the total mass of the strengthening phase elements Ni and Al, and the stirring time is 8min~10min after addition. The second batch is 40% of the total mass of the strengthening phase elements Ni and Al, and the stirring time is 8min~12min, and the holding time is 20min~30min after addition.

[0027] By precisely controlling the addition temperature between 1520℃ and 1550℃, we avoid excessively high temperatures that could cause Ni and Al to burn out, and excessively low temperatures that could lead to insufficient Ni and Al reactions. This ensures that Ni and Al react completely to form the NiAl strengthening phase, and that the NiAl phase is initially dispersed and distributed.

[0028] S2, Refining process: The molten steel is transferred to a refining furnace for high-purity refining and desulfurization treatment to obtain refined molten steel; Specifically, the refining process involves transferring the molten steel after smelting into a refining furnace, adding high-purity CaO-Al2O3-based refining slag, controlling the slag basicity to 3.8~4.8, blowing in argon gas and stirring, with a refining stirring speed of 90r / min~130r / min, a refining temperature of 1590℃~1630℃, a refining holding time of 45min~65min, a settling time of 5min~8min after refining, and removing the refining slag to obtain refined molten steel, thereby achieving a uniform distribution of the NiAl strengthening phase.

[0029] S3. Degassing and impurity removal process: The refined molten steel is transferred into a vacuum furnace and vacuum degassing and impurity removal are carried out using a two-stage temperature gradient to obtain high-quality molten steel with uniform composition and qualified purity. The degassing and impurity removal process is carried out under an argon atmosphere, with a two-stage temperature gradient treatment: The first stage of temperature treatment involves heating the refined molten steel to 1580℃~1650℃ and holding it at that temperature for 20min~30min, while controlling the stirring speed at 70r / min~90r / min. This step increases the diffusion rate of free hydrogen and oxygen, allowing them to escape rapidly in a vacuum environment, thus achieving efficient degassing. At the same time, the high temperature can cause some easily oxidizable impurities (such as FeO and MnO) to volatilize, thus initially removing some impurities.

[0030] The second stage of temperature treatment involves cooling the refined molten steel to 1500℃~1580℃ at a cooling rate of 5℃ / min~8℃ / min, holding it at that temperature for 30min~40min, and adjusting the stirring speed to 40r / min~60r / min.

[0031] This step accelerates the floating rate of non-metallic inclusions (such as Al2O3 and SiO2). By using argon gas to gently stir, it promotes the aggregation and floating of fine inclusions, which are eventually separated from the melt. During the low-temperature impurity removal stage, the cooling rate needs to be controlled at 5~8℃ / min to avoid uneven melt composition and inclusion residue caused by excessively rapid cooling, thus ensuring the purity of the alloy material.

[0032] Preferably, after the two-stage temperature gradient treatment is completed, the vacuum furnace is de-vacuumed, the stirring speed is controlled at 30 r / min to 50 r / min, and the stirring time is 15 min to 20 min.

[0033] After the vacuum treatment is completed and the vacuum is broken, argon gas is blown to stir the molten steel to avoid secondary oxidation of the molten steel and re-entry of inclusions, ensuring that the molten steel has uniform composition and meets the purity standards, thus providing high-quality molten steel for subsequent casting.

[0034] It should be noted that a two-stage temperature gradient purification process, consisting of high-temperature primary degassing and low-temperature secondary impurity removal, is adopted to replace the traditional single-stage constant-temperature melting purification mode. Through the synergistic complementarity of high and low temperature gradients, the technical defects of conventional melting processes, such as "incomplete gas removal, excessive non-metallic inclusions, easy burning of active alloying elements, and insufficient melt purity," are specifically addressed. High-temperature degassing accelerates the diffusion rate of H and O atoms in molten steel, providing favorable kinetic conditions for efficient degassing. Under high-temperature conditions, free hydrogen atoms and dissolved oxygen in the melt can rapidly aggregate, float, and be removed, effectively reducing the hydrogen and oxygen content of the molten steel. The gaseous components in the molten steel have H ≤ 1 ppm and O ≤ 10 ppm, which helps to mitigate hydrogen embrittlement and microporosity defects caused by hydrogen enrichment, while promoting the full melting and diffusion of alloying elements. Subsequently, lowering the temperature for impurity removal can efficiently promote the agglomeration, floating, and discharge of solid non-metallic inclusions such as sulfides and residual oxides from the melt, reducing the number and size of inclusions and achieving an inclusion grade of ≤ 1.0 in the molten steel, significantly improving the purity and density of the steel.

[0035] S4. Casting process: High-quality molten steel is continuously cast and cooled to room temperature to obtain steel billets; Specifically, during the continuous casting process, the cooling rate is controlled at 5℃ / min to 8℃ / min to ensure uniform distribution of the NiAl phase and avoid excessively fast cooling, which could lead to uneven NiAl phase structure and reduce the toughness or ductility of the material.

[0036] S5. Forming process: The steel billet is successively hot rolled, heat treated and drawn to obtain steel core single wire.

[0037] Specifically, hot rolling involves heating the steel billet to a hot rolling start temperature of 950℃~1050℃, holding it at that temperature for 30min~40min, and then hot rolling it. The final hot rolling temperature is controlled at 820℃~880℃, and the billet is then air-cooled to obtain hot-rolled wire rod.

[0038] The heat treatment involves isothermal quenching of the hot-rolled wire rod in a lead bath furnace, with the quenching temperature controlled at 500℃~650℃ and the quenching holding time at 60min~90min. Through isothermal quenching transformation, the wire rod obtains a uniform and fine pearlitic structure, further optimizing the NiAl phase distribution and improving the stability and dispersion of the coherent structure.

[0039] The drawing process involves drawing hot-rolled wire rods in multiple passes to obtain steel core single wires. The total drawing deformation is controlled at 60% to 75%, and the deformation per pass is controlled to not exceed 15% during the drawing process to avoid excessive drawing of the wire rod, which could lead to cracks. After drawing, steel core single wires are obtained.

[0040] The following specific embodiments were obtained by selecting different proportions of the component elements and preparation process parameters of the toughened steel core alloy material for overhead conductors.

[0041] Examples 1-8 and Comparative Example 1 Table 1 is a comparison table of chemical element ratios for the toughened steel core alloy materials used in overhead conductors of Examples 1-8 and Comparative Example 1, as follows: Table 1

[0042] Note: In Table 1, the balance of alloy materials in Examples 1-8 and Comparative Example 1 is iron and unavoidable impurities.

[0043] Table 2 is a comparison table of the main process parameters for the preparation methods of toughened steel core alloy materials for overhead conductors in Examples 1-8 and Comparative Example 1, as follows: Table 2

[0044] It should be noted that Table 2 above mainly lists the key preparation parameters. For preparation parameters not listed, those skilled in the art can use the defined parameter range or conventional values.

[0045] Test Results Mechanical performance tests were conducted on Examples 1-8 and Comparative Example 1. As shown in Table 3, Table 3 is a comparison table of tensile strength and elongation of Examples 1-8 and Comparative Example 1.

[0046] Table 3

[0047] A comparison of Tables 1, 2, and 3 shows that the alloy material composition ratio, dual-stage degassing and impurity removal parameters, and subsequent single-line preparation process parameters of the present invention have all been precisely optimized, resulting in high process stability. It can be modified based on existing high-carbon steel single-line production equipment without the need for additional complex equipment, and production costs are controllable. At the same time, the process flow is coherent, the coordination of each process is strong, the production efficiency is high, large-scale industrial production can be achieved, and the product performance fluctuation is small.

[0048] Ni and Al are the core elements for achieving high toughness and strength in this invention. They exhibit a synergistic effect in both chemical composition and microstructure. Ni, as an austenitizing alloying element, can dissolve in the iron matrix, reducing the resistance to dislocation movement and improving the plasticity and deformation resistance of the ferrite phase. Simultaneously, Ni can homogenize the alloy microstructure, alleviate lattice distortion stress caused by impurity elements, and inhibit crack initiation and propagation. Al is a strong deoxidizing and grain-refining element, capable of deeply removing residual oxygen from the melt and eliminating brittle oxide inclusions other than alumina. The intermetallic compounds precipitated from NiAl are uniformly dispersed in the α-phase as nano-sized particles. In a Fe matrix, and highly coherent with the matrix, coherent NiAl significantly improves tensile strength. The high-density, uniformly distributed coherent particles strongly pin dislocations and inhibit recovery, further enhancing strength and thermal stability. Unlike incoherent / semi-coherent second phases such as carbides and nitrides, coherent NiAl has a continuous interface with the matrix and no significant stress concentration. It can undergo synergistic plastic deformation with the matrix, allowing the material to maintain high elongation and toughness even at high strength, resolving the contradiction of traditional high-strength steel being "strong but not tough." In the experiments, Examples 1-4 showed continuous optimization of comprehensive mechanical properties with synchronous increases in Ni and Al content. Comparative Example 1, with a proportion exceeding the optimal range, also experienced a significant decrease in elongation, verifying that Ni and Al elements must be used in combination within a limited proportion range to achieve the optimal toughening effect.

[0049] Furthermore, a two-stage degassing and impurity removal process was employed to deeply deoxidize, reduce impurities, and homogenize the composition, creating pure and uniform melt and microstructure conditions for the uniform solid solution of Ni and Al and the subsequent formation of coherent NiAl nano-reinforcing phases. Compared with Example 1 and Comparative Example 1, the alloy material obtained by the two-stage temperature gradient degassing and impurity removal process in Example 1 exhibits superior strength and plasticity compared to the traditional degassing and impurity removal process. Comparative Examples 1-4 have the same matrix composition and process parameters, with only the Ni and Al content being gradually increased. As the Ni and Al content gradually increases, the number of coherent NiAl precipitates increases and their distribution becomes more uniform, continuously improving strength through coherent precipitation strengthening. At the same time, the coherent interface deforms synergistically with the matrix, avoiding stress concentration like that caused by hard carbides. While the strength increases, the elongation also increases significantly. When the Ni and Al contents increase by 0.5 and 0.25, respectively, and the element ratio approaches the upper limit range, the NiAl particles show slight coarsening, and the elongation decreases.

[0050] When the reinforcing phase elements Ni: 0.30%~0.50% and Al: 0.15%~0.25%, the tensile strength and elongation of Examples 2, 3, 4, 6, and 7 are generally balanced and exhibit excellent performance compared to other examples.

[0051] The alloy material composition design of this invention combines the deep synergy of processes such as two-stage degassing and impurity removal, forming, and heat treatment, which solves the problem of mutual interference between material design and preparation process in the prior art. This ensures that the NiAl strengthening phase is fully formed and uniformly distributed. At the same time, each preparation process is adapted to the alloy material, further amplifying the performance advantages. The single-wire drawing qualification rate is ≥99.5%, and the mechanical properties are uniform and stable.

[0052] The alloy material of this invention can be used for various overhead conductors, especially suitable for harsh working conditions such as ultra-high voltage, long span, heavy icing areas, and high humidity. It can also be stranded with existing aluminum alloy wires to form steel-cored aluminum stranded wires, which have strong compatibility and broad application prospects.

[0053] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A toughened steel core alloy material for overhead conductors, characterized in that, By mass percentage, it includes the following chemical elements: C: 0.75%~0.85%, Mn: 0.40%~0.90%, Si: 0.15%~0.25%, P≤0.005%, S≤0.005%; strengthening phase element Ni: 0.20%~0.60%, Al: 0.10%~0.30%; the balance is Fe and unavoidable impurity elements.

2. The toughened steel core alloy material for overhead conductors according to claim 1, characterized in that, The reinforcing phase elements are Ni: 0.30%~0.50% and Al: 0.15%~0.25%.

3. The toughened steel core alloy material for overhead conductors according to claim 1, characterized in that, The mass ratio of Ni to Al in the strengthening phase element is 2:

1.

4. A method for preparing a toughened steel core alloy material for overhead conductors according to any one of claims 1-3, characterized in that, include: Smelting process: Non-strengthening phase elements C, Mn, Si, P and S raw materials are added to the pretreated molten iron according to the chemical element ratio of the alloy material. After the non-strengthening phase elements melt, strengthening phase elements Ni and Al raw materials are added in batches to obtain molten steel with NiAl phase initially dispersed. Refining process: The molten steel is transferred to a refining furnace for high-purity refining and desulfurization treatment to obtain refined molten steel; Degassing and impurity removal process: The refined molten steel is transferred into a vacuum furnace and vacuum degassing and inclusion removal are carried out using a two-stage temperature gradient to obtain high-quality molten steel with uniform composition and qualified purity. Casting process: High-quality molten steel is continuously cast and cooled to room temperature to obtain steel billets; Forming process: The steel billet is successively hot rolled, heat treated and drawn to obtain steel core single wire.

5. The method for preparing toughened steel core alloy material for overhead conductors according to claim 4, characterized in that, The smelting process uses an electric arc furnace for smelting, with a smelting temperature of 1500℃~1580℃ and a smelting holding time of 20min~30min. To stabilize the temperature of the molten steel at 1520℃~1550℃, the strengthening phase elements Ni and Al raw materials were added in two batches. The first batch of addition is 60% of the total mass of the reinforcing phase elements Ni and Al raw materials, and the stirring time after addition is 8-10 minutes; The second batch of addition is 40% of the total mass of the reinforcing phase elements Ni and Al raw materials. The stirring time is 8 min to 12 min, and the heat preservation time after addition is 20 min to 30 min.

6. The method for preparing toughened steel core alloy material for overhead conductors according to claim 4, characterized in that, The pretreated molten iron is prepared by adding CaO-based flux to the molten iron and performing dephosphorization treatment under an oxidizing atmosphere. The molten iron temperature is 1320℃~1390℃ and the stirring speed is 110r / min~160r / min.

7. The method for preparing toughened steel core alloy material for overhead conductors according to claim 4, characterized in that, The refining process involves transferring the molten steel to a refining furnace, adding high-purity CaO-Al2O3-based refining slag, controlling the slag basicity to 3.8-4.8, blowing in argon gas and stirring, with a refining stirring speed of 90-130 r / min, a refining temperature of 1590℃-1630℃, a refining holding time of 45-65 min, a settling time of 5-8 min after refining, and then removing the refining slag to obtain refined molten steel.

8. The method for preparing toughened steel core alloy material for overhead conductors according to claim 4, characterized in that, The degassing and impurity removal process is carried out under an argon atmosphere, and the two-stage temperature gradient treatment is as follows: The first stage of temperature treatment involves heating the refined molten steel to 1580℃~1650℃, holding it at that temperature for 20min~30min, and controlling the stirring speed at 70r / min~90r / min. The second stage of temperature treatment involves cooling the refined molten steel to 1500℃~1580℃ at a cooling rate of 5℃ / min~8℃ / min, holding it at that temperature for 30min~40min, and adjusting the stirring speed to 40r / min~60r / min.

9. The method for preparing toughened steel core alloy material for overhead conductors according to claim 8, characterized in that, After the two-stage temperature gradient treatment is completed, the vacuum furnace is de-vacuumed, the stirring speed is controlled at 30 r / min to 50 r / min, and the stirring time is 15 min to 20 min.

10. The method for preparing toughened steel core alloy material for overhead conductors according to claim 4, characterized in that, During the continuous casting process of the aforementioned casting procedure, the cooling rate is controlled at 5℃ / min to 8℃ / min.

11. The method for preparing toughened steel core alloy material for overhead conductors according to claim 4, characterized in that, In the forming process, the hot rolling process involves heating the steel billet to a hot rolling start temperature of 950℃~1050℃, holding it at the hot rolling temperature for 30min~40min, and then hot rolling is performed. The final hot rolling temperature is controlled at 820℃~880℃, and the hot-rolled wire rod is obtained by air cooling after rolling.

12. The method for preparing toughened steel core alloy material for overhead conductors according to claim 4, characterized in that, In the forming process, the heat treatment involves isothermal quenching of the hot-rolled wire rod in a lead bath furnace, with the quenching temperature controlled at 500℃~650℃ and the quenching holding time at 60min~90min.

13. The method for preparing toughened steel core alloy material for overhead conductors according to claim 4, characterized in that, In the forming process, the drawing process involves drawing the hot-rolled wire rod in multiple passes to obtain a steel core single wire. The total drawing deformation is controlled at 60% to 75%, and the deformation per pass is controlled to not exceed 15% during the drawing process.

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