Corrosion-resistant sorbite high-carbon steel, steel wire and manufacturing method thereof

Abstract

The invention discloses corrosion-resistant sorbite high-carbon steel, which contains Fe and inevitable impurities, and further contains the following chemical elements in percentage by mass: 0.70 to 0.90 percent of C, 1.00 to 2.50 percent of Si, 0.30 to 0.90 percent of Mn, 0.30 to 0.90 percent of Cr, 0.01 to 0.30 percent of Ni, 0.01 to 0.30 percent of Al, and the balance of Fe and inevitable impurities. 0.30 wt.% or less of Zn; wherein the chemical elements also meet the following conditions: 0.1 < = 0.06 [Si] + 0.4 [Al] + 0.5 [Zn] < = 0.32. The invention further discloses a steel wire which is prepared from the corrosion-resistant sorbite high-carbon steel at least through drawing and galvanizing procedures. The invention also discloses the corrosion-resistant sorbite high-carbon steel, a steel wire and a manufacturing method thereof.

Description

Technical Field

[0001] This invention relates to a type of steel and its preparation method, and more particularly to a high-carbon steel, steel wire, and its manufacturing method. Background Technology

[0002] With the improvement of domestic manufacturing capabilities, technological research level, and the ability to apply new technologies, the requirements for bridge cables and their service life are further increasing.

[0003] For example, Chinese patent document CN110066963A, published on July 30, 2019, entitled "A 2000MPa Grade Galvanized Steel Wire for Bridge Cables and Its Manufacturing Method," discloses a 2000MPa grade galvanized steel wire for bridge cables and its manufacturing method. The chemical composition of the steel wire is: C = 0.88-0.94%, Si = 1.05-1.35%, Mn = 0.40-0.50%, Cr = 0.25-0.35%, Cu ≤ 0.07%, with the balance being Fe and unavoidable impurity elements, and also includes any one or more of B = 0.0005-0.0015%, Nb = 0.01-0.03%, and Mo = 0.01-0.03%. The produced galvanized steel wire can achieve a tensile strength of 2000MPa or higher and a torsion value of not less than 18 turns.

[0004] For example, Chinese patent document CN112458356A, published on March 9, 2021, entitled "A φ14mm wire rod for 1860MPa grade galvanized steel wire for bridge cables and its preparation method," discloses a φ14mm wire rod for 1860MPa grade galvanized steel wire for bridge cables and its preparation method. The chemical composition of the steel wire is: C = 0.84-0.88%, Si = 0.15-0.25%, Mn = 0. 0.65-0.80%, Cr=0.35-0.45%, P≤0.015%, S≤0.010%, Al≤0.005%. The finished steel wire after drawing and galvanizing has a strength higher than 1860MPa, a torsion value ≥17 times, and the core network cementite level of the wire rod can be guaranteed to be ≤1.0 grade, the decarburization depth can be guaranteed to be ≤0.7%D, the sorbitization rate can reach more than 95%, and the pearlite lamellar spacing can be guaranteed to be 100-150nm.

[0005] For example, Chinese patent document CN112501506A, published on March 16, 2021, entitled "A Steel Wire Rod for Bridge Cables and Its Manufacturing Method", discloses a steel wire rod for bridge cables and its manufacturing method. By scientifically and rationally combining the Cr, V, Al, and Si elements in the composition of the steel wire rod for bridge cables, and by adopting a reasonable manufacturing method, it reduces the number of processes, saves costs, and ensures the mechanical performance requirements of the wire rod.

[0006] However, in coastal areas, the air contains a large amount of chloride ions, which can react chemically with steel and corrode the surface of the steel wire, thus greatly shortening its lifespan. The aforementioned patent documents do not solve this technical problem. Summary of the Invention

[0007] One of the objectives of this invention is to provide a corrosion-resistant sorbitic high-carbon steel. By rationally designing the chemical element composition, a corrosion-resistant sorbitic high-carbon steel wire rod with good microstructure uniformity and excellent strength and plasticity can be obtained.

[0008] To achieve the above objectives, the present invention provides a corrosion-resistant sorbitic high-carbon steel containing Fe and unavoidable impurities, and further containing the following chemical elements in the following mass percentages:

[0009] C: 0.70~0.90wt.%, Si: 1.00~2.50wt.%, Mn: 0.30~0.90wt.%, Cr: 0.30~0.90wt.%, Ni: 0.01~0.30wt.%, Al: 0.01~0.30wt.%; Zn≤0.30wt.%;

[0010] The chemical elements also satisfy the following condition: 0.1≤0.06[Si]+0.4[Al]+0.5[Zn]≤0.32, where [Si], [Al], and [Zn] are respectively substituted with the values ​​before the mass percentage sign of each chemical element.

[0011] In this invention, considering the combined addition of Si, Al, and Zn elements, an Al-Zn-Si eutectic alloy structure can be formed between the steel substrate and the coating after the wire rod is drawn and galvanized. By controlling 0.1≤0.06[Si]+0.4[Al]+0.5[Zn]≤0.32, the Al-Zn-Si eutectic alloy structure can be made more stable, thus possessing unique corrosion resistance.

[0012] Furthermore, in the corrosion-resistant sorbitic high-carbon steel described in this invention, the mass percentage content of each chemical element is as follows:

[0013] C: 0.70–0.90 wt.%, Si: 1.00–2.50 wt.%, Mn: 0.30–0.90 wt.%, Cr: 0.30–0.90 wt.%, Ni: 0.01–0.30 wt.%, Al: 0.01–0.30 wt.%, Zn ≤ 0.30 wt.%, balance Fe and unavoidable impurities.

[0014] The design principles of each chemical element in the corrosion-resistant sorbitic high-carbon steel described in this invention are as follows:

[0015] C: In the corrosion-resistant sorbitic high-carbon steel described in this invention, carbon (C) is an essential chemical component for ensuring the strength of the steel. Increasing the C content in the steel is beneficial for forming more cementite lamellae and refining the sorbitic lamellar structure, thereby giving the steel better deformation and work hardening properties, which is beneficial for improving the strength of the steel wire during subsequent processing. When the mass percentage of C in the wire rod is too low, the strength of the material will not meet the requirements. When the mass percentage of C in the wire rod is too high, it will lead to increased component segregation during alloy solidification and deterioration of the material's toughness. Therefore, in the corrosion-resistant sorbitic high-carbon steel described in this invention, the mass percentage of C is controlled between 0.70 and 0.90 wt.%.

[0016] Si: In the corrosion-resistant sorbitic high-carbon steel described in this invention, Si is often added to the steel as a deoxidizer during the smelting process. Simultaneously, Si dissolved in the ferrite phase significantly improves the strength of the steel. Furthermore, during the cooling phase transformation process, Si accumulates at the interface between the ferrite and cementite phases. After degreasing and hot-dip galvanizing of the steel wire with a large reduction in surface area, the accumulation of Si at the phase interface slows down the decomposition of the cementite lamellars under large deformation, thereby effectively reducing the strength loss of the steel. When the mass percentage of Si in the wire rod is too high, it significantly reduces the plasticity of the steel, causing embrittlement. Therefore, in the corrosion-resistant sorbitic high-carbon steel described in this invention, the mass percentage of Si is controlled between 1.00 and 2.50 wt.%.

[0017] Mn: In the corrosion-resistant sorbitic high-carbon steel described in this invention, Mn is added to the steel as a deoxidizer during the steelmaking process. Simultaneously, Mn readily combines with sulfur (S), a harmful element in steel, to form MnS, thereby reducing its harmful effects. Furthermore, Mn is a commonly used strengthening element in steel, primarily playing a role in solid solution strengthening, resulting in alloy cementite with higher strength. However, the Mn content in the steel should not be too high. When the mass percentage of Mn in the wire rod is too high, it will increase the tendency for grain coarsening during heating, making it more difficult to control the microstructure during controlled cooling. Therefore, in the corrosion-resistant sorbitic high-carbon steel described in this invention, the mass percentage of Mn is controlled between 0.30 and 0.90 wt.%.

[0018] Cr: In the corrosion-resistant sorbitic high-carbon steel described in this invention, the addition of Cr element is beneficial for refining the lamellar structure of the sorbitic microstructure and improving the strength of cementite, thereby effectively improving the strength and plasticity of the material. To ensure that Cr element can effectively exert its benefits, the Cr element content in the steel needs to be higher than 0.30%. Correspondingly, to prevent the occurrence of abnormal martensitic microstructure and reduce the difficulty of microstructure control, the Cr element content in the steel needs to be controlled below 0.90%. Therefore, in the corrosion-resistant sorbitic high-carbon steel described in this invention, the mass percentage content of Cr element is controlled between 0.30 and 0.90 wt.%.

[0019] Ni: In the corrosion-resistant sorbitic high-carbon steel described in this invention, Ni can stabilize the supercooled austenite phase, which is beneficial for increasing the content of sorbite and troostite phases in the wire rod, reducing the interlamellar spacing, and thus improving strength and plasticity. However, when the mass percentage content of Mn in the steel is too high, it will increase the cost and easily lead to abnormal martensitic structures. Therefore, in the corrosion-resistant sorbitic high-carbon steel described in this invention, the mass percentage content of Ni is controlled between 0.01 and 0.30 wt.%.

[0020] Al: In the corrosion-resistant sorbitic high-carbon steel described in this invention, Al is a deoxidizer, and its deoxidizing ability is much stronger than that of Si and Mn. Simultaneously, Al is an effective element for adjusting the grain size of steel; during solidification, a large amount of finely dispersed alumina promotes the formation of fine-grained steel. When the mass percentage content of Al in the wire rod is too high, the coarse alumina will severely reduce the drawing and fatigue properties of the wire rod and galvanized steel wire. Therefore, in the corrosion-resistant sorbitic high-carbon steel described in this invention, the mass percentage content of Al is controlled between 0.01 and 0.30 wt.%.

[0021] Zn: In the corrosion-resistant sorbitic high-carbon steel described in this invention, the standard potential of Zn is -0.76V, while the standard potentials of V and Fe are -0.44V. Zn acts as the anode and is corroded first in electrochemical corrosion, thus protecting the steel wire matrix. Therefore, in the corrosion-resistant sorbitic high-carbon steel described in this invention, the mass percentage of Zn is controlled to be ≤0.30 wt.%.

[0022] Furthermore, in the unavoidable impurities of the corrosion-resistant sorbitic high-carbon steel described in this invention: P ≤ 0.015 wt.%, S ≤ 0.015 wt.%.

[0023] It should be noted that in the above technical solution of the present invention, P and S elements are both impurity elements in the corrosion-resistant sorbitic high-carbon steel of the present invention. When technical conditions permit, in order to obtain steel with better performance and higher quality, the content of impurity elements in the steel should be reduced as much as possible.

[0024] P and S: In the corrosion-resistant sorbitic high-carbon steel described in this invention, impurity elements P and S tend to segregate at grain boundaries, reducing the steel's toughness and significantly affecting its cold-working properties. Therefore, in the corrosion-resistant sorbitic high-carbon steel described in this invention, the content of P and S elements must be strictly controlled. The mass percentage of P can be controlled to P ≤ 0.015 wt.%, and the mass percentage of S can be controlled to S ≤ 0.015 wt.%.

[0025] Furthermore, in the corrosion-resistant sorbitic high-carbon steel described in this invention, its properties meet the following requirements: sorbitization rate ≥ 85%, tensile strength ≥ 1300 MPa, and reduction of area ≥ 30%.

[0026] Another objective of this invention is to provide a steel wire that, after being drawn, galvanized, and stabilized, exhibits significant advantages in corrosion resistance and can be effectively applied to steel wire products for long-span suspension bridges and cable-stayed bridges.

[0027] To achieve the above objectives, the present invention provides a steel wire made from the aforementioned corrosion-resistant sorbitic high-carbon steel through at least drawing and galvanizing processes.

[0028] Furthermore, in the steel wire described in this invention, the tensile strength is ≥2000MPa and the number of torsion cycles is ≥12.

[0029] Furthermore, in the steel wire described in this invention, the corrosion time exceeds 1000 hours in an acidic solution environment.

[0030] Another objective of this invention is to provide a method for manufacturing corrosion-resistant sorbitic high-carbon steel. This method, by controlling the online air-cooling process of wire rod, can obtain corrosion-resistant sorbitic high-carbon steel with good microstructure uniformity and excellent strength and plasticity.

[0031] To achieve the above objectives, the present invention provides a method for manufacturing corrosion-resistant sorbitic high-carbon steel, comprising the following steps:

[0032] Smelting and casting;

[0033] Rolled into wire rod;

[0034] Online air cooling of wire rod: control the spinning temperature at 900-920℃, the rapid air cooling time is 40-60s, and the temperature of the wire rod after cooling is 510-560℃, and then keep it warm.

[0035] Furthermore, in the online air-cooling step of the manufacturing method of corrosion-resistant sorbitic high-carbon steel described in this invention, the wire rod enters the insulation hood for insulation for ≥30s, and the temperature of the wire rod exiting the insulation hood is 460~500℃.

[0036] Another objective of this invention is to provide a method for manufacturing steel wire. This method involves drawing, galvanizing, and stabilizing corrosion-resistant sorbitic high-carbon steel into steel wire, which can achieve significant advantages in corrosion resistance and can be effectively applied to steel wires for long-span suspension bridges and cable-stayed bridges.

[0037] To achieve the above objectives, the present invention provides a method for manufacturing steel wire, comprising the steps of:

[0038] Smelting and casting;

[0039] Rolled into wire rod;

[0040] Online air cooling of wire rod: control the spinning temperature at 900-920℃, the rapid air cooling time is 40-60s, the temperature of the wire rod after cooling is 510-560℃, and then keep it at the temperature;

[0041] Pull;

[0042] Galvanized.

[0043] Furthermore, in the online air-cooling step of the manufacturing method described in this invention, the wire rod enters the insulation cover for insulation for ≥30s, and the temperature exiting the insulation cover is 460~500℃.

[0044] Furthermore, in the drawing step of the manufacturing method described in this invention, the total drawing compression is controlled to be ≤80% and the single-pass compression is controlled to be ≤20%.

[0045] Furthermore, in the zinc plating step of the manufacturing method described in this invention, the zinc plating temperature is controlled to be 430–470°C, and / or the zinc plating time is 40–90 seconds.

[0046] The corrosion-resistant sorbitic high-carbon steel, steel wire, and their manufacturing method described in this invention have the following advantages and beneficial effects compared to the prior art:

[0047] The corrosion-resistant sorbitic high-carbon steel described in this invention, through rational design of chemical element composition and optimization of online air cooling process for wire rod, can produce a corrosion-resistant sorbitic high-carbon steel wire rod with good microstructure uniformity and excellent strength and plasticity.

[0048] In some embodiments, the corrosion-resistant sorbitic high-carbon steel of the present invention has a sorbitization rate of ≥85%, a tensile strength of ≥1300MPa, and a reduction of area of ​​≥30%.

[0049] The corrosion-resistant sorbitic high-carbon steel wire described in this invention, after being drawn, galvanized, and stabilized into steel wire, has significant advantages in corrosion resistance and can be effectively applied to steel wire products for long-span suspension bridges and cable-stayed bridges.

[0050] In some embodiments, the corrosion-resistant sorbitic high-carbon steel wire of the present invention has a tensile strength ≥2000MPa, a torsion cycle ≥12 times, and can be corroded in an NH4SCN solution environment with pH=5 for more than 1000h. Detailed Implementation

[0051] The corrosion-resistant sorbitic high-carbon steel, steel wire, and their manufacturing method described in this invention will be further explained and illustrated below with reference to specific embodiments. However, this explanation and illustration do not constitute an undue limitation on the technical solution of this invention.

[0052] Examples 1-10

[0053] The corrosion-resistant sorbitic high-carbon steels described in Examples 1-10 of this invention were all prepared using the following steps:

[0054] (1) Smelting and casting: Smelting can be carried out in an electric furnace or converter, followed by ladle refining. It should be noted that during ladle refining, an LF furnace with VD or RH degassing treatment process can be used, controlling the vacuum degassing time to be >20 min and the calming time to be >20 min. Casting can use the end-of-solidation light reduction technique, and the carbon segregation in the billet core can be controlled by adjusting the superheat of the tundish, the billet casting speed, cooling, and reduction amount.

[0055] (2) Rolled into wire rod;

[0056] (3) Online air cooling of wire rod: control the spinning temperature to 900-920℃, the rapid air cooling time to 40-60s, and the temperature of the wire rod after cooling to 510-560℃; then keep it warm. In some embodiments, it can be kept warm in an insulation hood for ≥30s, and the temperature of the wire rod after leaving the insulation hood is 460-500℃.

[0057] The steel wires of Examples 1-10 of this invention are further prepared using the following steps based on the corrosion-resistant sorbitic high-carbon steel obtained in each example:

[0058] (4) Drawing: During the drawing process, the total compression amount can be controlled to be ≤80%, and the compression amount per pass can be ≤20%;

[0059] (5) Galvanizing: During the galvanizing process, the galvanizing temperature can be controlled between 430 and 470°C, and the galvanizing time can be controlled between 40 and 90 seconds.

[0060] Table 1 lists the mass percentage of each chemical element in the corrosion-resistant sorbitic high-carbon steels of Examples 1-10 of the present invention.

[0061] Table 1. (wt%, balance Fe and other unavoidable impurities besides P and S)

[0062] serial number C Si Mn Cr Ni Al Zn P S H value Example 1 0.70 1.50 0.70 0.30 0.20 0.03 0 0.009 0.007 0.10 Example 2 0.72 1.80 0.40 0.50 0.14 0.02 0.1 0.007 0.015 0.17 Example 3 0.75 2.50 0.60 0.70 0.01 0.30 0.1 0.011 0.009 0.32 Example 4 0.79 2.00 0.90 0.40 0.05 0.05 0.3 0.015 0.012 0.29 Example 5 0.81 1.90 0.30 0.90 0.09 0.01 0.2 0.008 0.009 0.22 Example 6 0.80 1.00 0.40 0.60 0.12 0.2 0.02 0.010 0.013 0.15 Example 7 0.86 1.40 0.50 0.40 0.23 0.17 0.18 0.014 0.012 0.24 Example 8 0.83 1.20 0.40 0.50 0.30 0.12 0.26 0.012 0.014 0.25 Example 9 0.85 1.60 0.80 0.30 0.25 0.21 0.13 0.011 0.015 0.25 Example 10 0.90 2.10 0.30 0.80 0.19 0.18 0.08 0.013 0.008 0.24

[0063] Note: H = 0.06[Si] + 0.4[Al] + 0.5[Zn], where [Si], [Al], and [Zn] are respectively replaced by the values ​​before the mass percentage sign of the corresponding chemical element.

[0064] Table 2 lists the specific process parameters of the corrosion-resistant sorbitic high-carbon steel of Examples 1-10 of the present invention in the above process steps.

[0065] Table 2.

[0066]

[0067]

[0068] Table 3 lists the specific process parameters of the steel wires in Examples 1-10 of the present invention in the above process steps.

[0069] Table 3.

[0070]

[0071] Samples of the corrosion-resistant sorbitic high-carbon steels of Examples 1-10, prepared through steps 1-3 above, were taken, and relevant performance tests were performed on the steel samples of each example. The results of the relevant performance tests are listed in Table 4. The methods for testing the relevant mechanical properties are as follows:

[0072] Microstructure: Metallographic structure was tested in accordance with GB / T 13298—2015 "Metallic Microstructure Examination Method".

[0073] Mechanical property testing: Mechanical property testing shall be conducted in accordance with GB / T 228.1—2010 "Metallic materials, tensile testing - Part 1: Test method at room temperature".

[0074] Table 4 lists the relevant performance test results of the corrosion-resistant sorbitic high-carbon steels of Examples 1-10 of the present invention.

[0075] Table 4.

[0076]

[0077]

[0078] As can be seen from Table 4 above, the sorbitization rate of the corrosion-resistant sorbitic high-carbon steels of Examples 1-10 of the present invention is greater than or equal to 85%, the tensile strength is greater than or equal to 1300 MPa, and the reduction of area is greater than or equal to 30%.

[0079] Furthermore, samples were taken from the steel wires of Examples 1-10 of the present invention obtained through steps 1-5 above, and relevant performance tests were performed on the steel wires of each example. The results of the performance tests are listed in Table 5. The relevant performance testing methods are as follows:

[0080] Mechanical property testing: Mechanical property testing shall be conducted in accordance with GB / T 228.1—2010 "Metallic materials, tensile testing - Part 1: Test method at room temperature".

[0081] Torsion test: The torsion test shall be conducted in accordance with GB / T 239.1—2023 "Metallic materials and wires - Part 1: Unidirectional torsion test method".

[0082] Corrosion resistance test: The steel wire was subjected to a constant stress of 1600 MPa and immersed in an NH4SCN solution with pH=5. The corrosion fracture time of the steel wire was calculated.

[0083] Table 5 lists the performance test results of the steel wires in Examples 1-10 of the present invention.

[0084] Table 5.

[0085]

[0086]

[0087] As can be seen from Table 5 above, the steel wires of Examples 1-10 of the present invention have significant advantages in corrosion resistance. Their corrosion resistance time is greater than or equal to 1000h, their tensile strength is greater than or equal to 2000MPa, and their torsion cycles are greater than or equal to 12. They can be effectively applied to steel wire products for long-span suspension bridges and cable-stayed bridges.

[0088] Furthermore, the combination of the technical features in this case is not limited to the combination methods described in the claims of this case or the combination methods described in the specific embodiments. All technical features described in this case can be freely combined or combined in any way, unless they contradict each other.

[0089] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A corrosion-resistant sorbitic high-carbon steel, containing Fe and unavoidable impurities, characterized in that, It also contains the following chemical elements in the following percentages by mass: C: 0.70~0.90wt.%, Si: 1.00~2.50wt.%, Mn: 0.30~0.90wt.%, Cr:

0. 30~0.90wt.%, Ni: 0.01~0.30wt.%, Al: 0.01~0.30wt.%; Zn≤0.30wt.%; The chemical elements also satisfy the following condition: 0.1≤0.06[Si]+0.4[Al]+0.5[Zn]≤0.32, where [Si], [Al], and [Zn] are respectively substituted with the values ​​before the mass percentage sign of each chemical element.

2. The corrosion-resistant sorbitic high-carbon steel as described in claim 1, characterized in that, Its mass percentage content of each chemical element is as follows: C: 0.70~0.90wt.%, Si: 1.00~2.50wt.%, Mn: 0.30~0.90wt.%, Cr: 0.30~0.90wt.%, Ni: 0.01~0.30wt.%, Al: 0.01~0.30wt.%; Zn≤0.30wt.%; The balance is Fe and unavoidable impurities.

3. The corrosion-resistant sorbitic high-carbon steel as described in claim 1 or 2, characterized in that, In unavoidable impurities: P ≤ 0.015 wt.%, S ≤ 0.015 wt.%.

4. The corrosion-resistant sorbitic high-carbon steel as described in claim 1 or 2, characterized in that, Its performance meets the following requirements: sorbitization rate ≥ 85%, tensile strength ≥ 1300 MPa, and reduction of area ≥ 30%.

5. A steel wire, characterized in that, It is made from corrosion-resistant sorbitic high-carbon steel as described in any one of claims 1-4 through at least drawing and galvanizing processes.

6. The steel wire as described in claim 5, characterized in that, Its tensile strength is ≥2000MPa and its torsion cycles are ≥12.

7. The steel wire as described in claim 5, characterized in that, In an acidic solution environment, the corrosion time exceeds 1000 hours.

8. The method for manufacturing corrosion-resistant sorbitic high-carbon steel according to any one of claims 1-4, characterized in that, It includes the following steps: Smelting and casting; Rolled into wire rod; Online air cooling of wire rod: control the spinning temperature at 900-920℃, the rapid air cooling time is 40-60s, and the temperature of the wire rod after cooling is 510-560℃, and then keep it warm.

9. The method for manufacturing corrosion-resistant sorbitic high-carbon steel as described in claim 8, characterized in that, In the online air-cooling process of wire rod, the wire rod enters the insulation cover for insulation for ≥30 seconds, and the temperature exiting the insulation cover is 460~500℃.

10. The method for manufacturing steel wire according to any one of claims 5-8, characterized in that, Including the following steps: Smelting and casting; Rolled into wire rod; Online air cooling of wire rod: control the spinning temperature at 900-920℃, the rapid air cooling time is 40-60s, the temperature of the wire rod after cooling is 510-560℃, and then keep it at the temperature; Pull; Galvanized.

11. The method for manufacturing steel wire as described in claim 10, characterized in that, In the online air-cooling process of wire rod, the wire rod enters the insulation cover for insulation for ≥30 seconds, and the temperature exiting the insulation cover is 460~500℃.

12. The method for manufacturing steel wire as described in claim 10, characterized in that, During the drawing process, the total compression amount should be controlled to be ≤80%, and the compression amount per pass should be ≤20%.

13. The method for manufacturing steel wire as described in claim 10, characterized in that, In the galvanizing process, the galvanizing temperature is controlled at 430–470°C, and / or the galvanizing time is 40–90 seconds.

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