Super-large-force-value steel strand and manufacturing method thereof

Abstract

The invention relates to the technical field of steel strand production, in particular to a super-large-force steel strand and a manufacturing method thereof, and the manufacturing method of the super-large-force steel strand comprises the following steps: S1, selection of a wire rod, and detection experiment of the wire rod; s2, first water washing, acid pickling and second water washing; s3, drawing after washing, and inspecting a semi-finished product; s4, assistant plating; s5, hot galvanizing; s6, drawing after plating; s7, stranding is carried out; s8, stabilizing treatment is carried out; s9, layer winding and finished product inspection; s10, official testing is carried out; and S11, packaging and warehousing. The super-large-force-value steel strand has the effects of high strength, high corrosion resistance and high stability.

Description

Technical Field

[0001] The present application relates to the technical field of steel strand production, and in particular to an ultra-high-force steel strand and a method for manufacturing the same. Background Art

[0002] The field of metal processing technology, particularly the preparation of high-strength steel strands, has seen rapid development in recent years. Due to their exceptional mechanical properties and excellent corrosion resistance, these strands are widely used in bridge cables, prestressed concrete structures, mine supports, and marine engineering. These applications place extremely stringent demands on the strands, requiring them to possess not only high strength but also excellent corrosion resistance and structural stability to withstand a variety of harsh operating environments.

[0003] In existing steel strand production processes, various methods are typically employed to optimize production and processing to improve the strand's overall performance. For example, the quality of the base material is ensured by selecting the appropriate wire rod material and strictly controlling its chemical composition. A multi-stage wire drawing process gradually reduces the wire diameter, improving its microstructure. Pickling and phosphating enhance the strand's corrosion resistance. Precise tension control ensures uniform distribution of the strands during stranding, improving the strand's overall mechanical properties. Furthermore, some processes incorporate stabilization steps, such as tempering heat treatment, to further enhance the strand's mechanical properties.

[0004] However, despite the progress made in existing technologies, there is still room for improvement in practical applications. The protective layer formed by conventional pickling and phosphating processes is not dense enough and easily peels off, making it unable to withstand the effects of harsh environments for a long time. Secondly, the structural stability is poor. Due to the uneven force caused by the arrangement of steel wires during the twisting process, the overall steel strand appears loose, affecting its mechanical performance. These problems limit the application of steel strand in high-end engineering fields, and a new process that can comprehensively address these shortcomings is urgently needed. Summary of the Invention

[0005] In order to overcome the above problems, the present application provides an ultra-high-force steel strand and a method for manufacturing the same.

[0006] The present application provides a method for manufacturing an ultra-high-capacity steel strand using the following technical solutions: A method for manufacturing an ultra-high-force steel strand comprises the following steps: S1, wire rod selection and wire rod testing experiment; S2, first water washing, acid washing, second water washing; S3, drawing after washing and semi-finished product inspection; S4, surface treatment; S5, twisted strands; S6, stabilization treatment; S7, layer winding and finished product inspection, where the upper deviation of the nominal diameter of the finished product of the ultra-high-force steel strand is +0.40mm, the lower deviation of the nominal diameter is -0.15mm, the center wire diameter is 7.71mm, the inner wire diameter is 7.40mm, the outer thick wire diameter is 8.04mm, and the outer thin wire diameter is 6.04mm; S8, official test; S9, packaging and storage.

[0007] By adopting the above technical solutions, the steel strand achieves high strength, high corrosion resistance, and high stability. Specifically, rigorous wire rod screening and testing ensures raw material quality; multi-stage water washing and pickling effectively remove surface impurities, improving the quality of subsequent processes; precise control of drawing parameters optimizes the internal crystal structure of the steel wire, significantly increasing tensile strength; hot-dip galvanizing combined with mist cooling creates a dense and uniform coating, enhancing corrosion resistance; and rational stranding technology and stabilization treatment ensure the overall mechanical properties and service life of the steel strand.

[0008] Optionally, in the selection of the wire rod in S1, wire rods of the same brand and specification are selected, and their chemical composition meets the following requirements: C: 0.84-0.860%, Si: 0.75-0.79%, Mn: 0.72-0.74%, P: 0.008-0.012%, S: 0.0045-0.005%, Cr: 0.04-0.05%, Ni: 0.001-0.002%, Cu: 0.001-0.002%, and the rest are Fe and unavoidable impurity elements.

[0009] By adopting the above technical solution, the optimized wire rod chemical composition ensures excellent mechanical properties and metallurgical quality. Specifically, the carbon content ranges from 0.84-0.860%, improving the hardness and strength of the steel wire; the silicon content ranges from 0.75-0.79%, enhancing the hardenability and oxidation resistance of the steel wire; the manganese content ranges from 0.72-0.74%, improving the plasticity and toughness of the steel wire; the phosphorus content ranges from 0.008-0.012% and the sulfur content ranges from 0.0045-0.005%, reducing the impact of harmful impurities and the formation of non-metallic inclusions; and the trace additions of chromium, nickel, and copper (0.04-0.05%, 0.001-0.002%, and 0.001-0.002%, respectively) further enhance the steel wire's corrosion resistance and weldability. The optimized combination of these components enables the final steel strand to have higher tensile strength, better toughness and better corrosion resistance, thus better meeting the stringent requirements of applications such as bridge cables, prestressed concrete structures, mine supports and marine engineering.

[0010] Optionally, in the first water washing in S2, a high-pressure water gun is used to wash away dust on the surface of the wire rod with water of not less than 80°C. In the pickling in S2, the wire rod is opened and immersed in a hydrochloric acid pickling tank for 10-15 minutes to remove surface oxides and oil stains. After pickling, in the second water washing in S2, a high-pressure water gun is used to wash away residual acid on the surface of the steel wire with water of not less than 80°C. The washing pressure is 5MPa or above, and then hot air drying is performed. The temperature of the hot air drying is 80°C-100°C.

[0011] The above technical solution effectively removes dust and oxides from the wire rod surface, ensuring the quality of subsequent processes. High-pressure flushing also thoroughly removes residual acid, preventing secondary corrosion of the wire. High-temperature water washing and hot air drying quickly evaporate moisture, preventing rust and ensuring the cleanliness and smoothness of the wire surface, laying a good foundation for subsequent drawing and galvanizing processes.

[0012] Optionally, during the pickling in S2, a corrosion inhibitor, benzotriazole, is added to the pickling tank at a concentration of 0.1-0.3 wt%.

[0013] By adopting the above technical solution, the addition of the corrosion inhibitor benzotriazole can effectively reduce the excessive corrosion of the steel wire matrix by hydrochloric acid during the pickling process, protect the surface quality of the steel wire, thereby improving the quality of subsequent drawing and galvanizing processes, and ultimately improving the overall performance of the steel strand.

[0014] Optionally, in the post-wash drawing in S3, the center wire is drawn from 15.0 mm wire rod to 7.67 mm through 9 passes, the inner layer wire is drawn from 15.0 mm wire rod to 7.36 mm through 9 passes, the outer layer thick wire is drawn from 15.0 mm wire rod to 8.00 mm through 8 passes, and the outer layer thin wire is drawn from 15.0 mm wire rod to 6.00 mm through 11 passes.

[0015] By adopting this technical solution, the center wire, inner wire, outer thick wire, and outer thin wire are each drawn in multiple passes to a preset diameter, resulting in a more compact internal structure and improved overall strength and tensile properties. Furthermore, precise control of the transition dimensions of each wire ensures uniformity and consistency during the subsequent galvanizing and stranding processes, thereby enhancing product quality and stability.

[0016] Optionally, the surface treatment in S4 includes the following steps: S4-a1 plating flux, the plating flux comprises the following components in parts by weight: 1.91%-1.92% zinc chloride, 0.50%-0.51% sodium chloride, 0.34%-0.35% sodium fluoride, 0.59%-0.60% surfactant Fc, and the remainder water; S4-a2 hot-dip galvanizing: immerse the steel wire in zinc solution for 5-8 seconds. The chemical composition of the zinc solution includes Al: 0.17%-0.20%, Ni: 0.12%-0.25%, Sn: 0.30%-0.50%, Sr: 0.05%-0.45%, Bi: 0.12%-0.25%, Pb: 0.12%-0.22%, Sb: 0.04%-0.06%, Fe: 0.02%-0.05%, and the rest are Zn and unavoidable impurity elements. The amount of zinc applied is 290g / m2-350g / m2. After galvanizing, mist cooling is used to quickly solidify the coating. The nitrogen pressure used for mist cooling is 0.3MPa-0.5MPa. S4-a3 is drawn after plating. The center wire is drawn to 7.71mm after plating, the inner wire is drawn to 7.40mm after plating, the outer thick wire is drawn to 8.04mm after plating, and the outer thin wire is drawn to 6.04mm after plating.

[0017] By employing the above-mentioned technical solution, the specific composition of the flux effectively improves the cleanliness and wettability of the steel wire surface, thereby enhancing the quality of the subsequent zinc coating. Specifically, the combination of zinc chloride, sodium chloride, and sodium fluoride helps remove minute impurities from the steel wire surface and strengthens the bonding between the zinc solution and the steel wire substrate. The use of surfactant Fc (a composite surfactant composed of a mixture of fluorine-carbon and carbon-hydrogen chain surfactants) further reduces interfacial tension and promotes uniform distribution of the zinc solution on the steel wire surface, resulting in a denser and more uniform zinc coating. This not only improves the adhesion of the coating but also enhances the overall corrosion resistance and mechanical properties of the steel strand. The specific chemical composition ratio of the zinc solution during the hot-dip galvanizing process significantly improves the density and adhesion of the coating, enhancing the corrosion resistance of the steel strand. Furthermore, the zinc coating weight is controlled within the range of 290g / m² to 350g / m², ensuring sufficient thickness and uniformity of the coating, further enhancing the corrosion resistance and tensile strength of the steel strand. Mist cooling uses nitrogen at a pressure of 0.3MPa-0.5MPa to accelerate the solidification process of the coating, prevent defects on the coating surface, and ensure the quality and stability of the coating. These measures work together to ensure that the steel strand not only has excellent corrosion resistance, but also can maintain good mechanical properties for a long time in harsh environments. Post-plating drawing can make the wire diameter dimensions of each layer of the steel strand more precise, improving the overall mechanical properties of the steel strand. Specifically, the dimensions of the center wire, inner wire, outer thick wire, and outer thin wire after post-plating drawing are 7.71mm, 7.40mm, 8.04mm, and 6.04mm, respectively, which makes the steel strand have a more uniform distribution and higher strength when it is finally formed. At the same time, this process also helps to improve the corrosion resistance and structural stability of the steel strand, thereby extending its service life.

[0018] Optionally, in the post-wash drawing in S3, the center wire is drawn from 15.0 mm wire rod to 7.71 mm through 9 passes, the inner layer wire is drawn from 15.0 mm wire rod to 7.40 mm through 9 passes, the outer layer thick wire is drawn from 15.0 mm wire rod to 8.04 mm through 8 passes, and the outer layer thin wire is drawn from 15.0 mm wire rod to 6.04 mm through 11 passes.

[0019] By adopting this technical solution, the center wire, inner wire, outer thick wire, and outer thin wire are each drawn in multiple passes to the preset diameter, making the internal structure of the steel strand more compact and improving the overall strength and tensile properties of the steel strand. Furthermore, precise control of the final dimensions of each wire ensures uniformity and consistency during the subsequent galvanizing and stranding processes, thereby improving product quality and stability.

[0020] Optionally, the surface treatment in S4 includes the following steps: S4-b1 phosphating, the phosphating process temperature is not less than 80°C, the drying time is ≥0.2min, and the phosphating process forms a layer of carrier on the surface, namely, a phosphating film, which plays a role in lubrication and rust prevention.

[0021] By adopting the above technical solution, a dense, uniform and highly firm phosphating film can be formed, thereby improving the corrosion resistance of the surface of the finished steel strand and meeting the lubrication, rust prevention and corrosion resistance requirements of the steel strand.

[0022] Optionally, in the stranding of S5, 19 galvanized steel wires are twisted in layers according to a 1+6+12 structure, the spacing between the outer thick wire and the outer thin wire is 0.16 mm, the spacing between the inner wires is 0.17 mm, the outer layer steel wires are twisted in the right direction, and the twist pitch is 12.5 times the nominal diameter of the steel strand. During twisting, the tension of each steel wire is monitored in real time by a tension sensor, and the deviation is controlled to not exceed 5%; in the stabilization treatment of S8, the tempering temperature is 405~415℃, the production line operating speed is lower than 9m / min, the tension of the steel strand is controlled at 30%-35% of the threshold force of the steel strand, and the cooling after tempering adopts a direct cooling immersion cooling method.

[0023] By adopting the above technical solution, the outer layer of steel wire is twisted in the right direction, and the lay pitch is 12.5 times the nominal diameter of the steel strand, which makes the steel strand have a more stable structure and improves the overall mechanical properties and fatigue resistance. During twisting, the tension of each steel wire is monitored in real time by a tension sensor, and the deviation is controlled to not exceed 5%, ensuring the uniform distribution of tension inside the steel strand and enhancing the overall strength and durability of the steel strand. The tempering temperature is 405~415℃, the production line operating speed is less than 9m / min, and the tension of the steel strand is controlled at 30%-35% of the threshold force of the steel strand, further optimizing the microstructure of the steel strand and improving its mechanical properties. The cooling after tempering adopts a direct cooling immersion cooling method, which effectively prevents the accumulation of internal stress and extends the service life of the steel strand.

[0024] Optionally, the nominal tensile strength of the ultra-high-force steel strand is at the 1960 MPa level, corresponding to a maximum force of 1395 kN to 1699 kN, a 0.2% yield strength of not less than 1310, and a total elongation at maximum force ≥3.5%.

[0025] By adopting this technical solution, the nominal tensile strength of the steel strand reaches 1770-1960 MPa, capable of withstanding maximum forces of 1395 kN-1699 kN, ensuring high-strength properties. Furthermore, the 0.2% yield strength is no less than 1310 kN, ensuring sufficient load-bearing capacity in the initial loading phase. Furthermore, the total elongation at maximum force is ≥3.5%, enhancing the ductility and toughness of the steel strand and strengthening its adaptability and safety in complex working conditions.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. High strength: The multi-stage wire drawing process optimizes the steel wire crystal structure, ensuring that the nominal tensile strength of the steel strand reaches 1960MPa and the maximum force is between 1395kN and 1699kN, reaching a force value that cannot be achieved by steel strands produced by traditional processes; 2. Excellent corrosion resistance: The use of galvanized layer improves the density and adhesion of the coating, which increases the salt spray resistance of the steel strand by more than 50%, and significantly improves the problem of easy peeling of the protective layer in the conventional pickling and phosphating process; 3. High stability: Through tension uniformity control technology and precise stranding parameter settings, the steel strand structure is ensured to be tight and the fatigue life is increased by 30%, overcoming the loose structure problem caused by uneven tension or unreasonable wire gap in traditional processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic cross-sectional view of the ultra-high-capacity steel strand in this application. DETAILED DESCRIPTION

[0028] The following is combined with Figure 1This application is described in further detail. Example

[0029] The present invention discloses a method for manufacturing an ultra-high-strength steel strand, comprising the following steps: S1 wire rod selection and wire rod testing experiment First, select high-carbon steel wire rod of the same grade and specification, with a chemical composition meeting the following criteria: C: 0.84-0.860%, Si: 0.75-0.79%, Mn: 0.72-0.74%, P: 0.008-0.012%, S: 0.0045-0.005%, Cr: 0.04-0.05%, Ni: 0.001-0.002%, Cu: 0.001-0.002%, with the remainder being Fe and unavoidable impurities. This chemical composition ensures the strands possess excellent mechanical properties and metallurgical quality. Specifically, the carbon content ranges from 0.84% to 0.860%, enhancing the wire's hardness and strength; the silicon content ranges from 0.75% to 0.79%, enhancing the wire's hardenability and oxidation resistance; the manganese content ranges from 0.72% to 0.74%, improving the wire's plasticity and toughness; the phosphorus content ranges from 0.008% to 0.012%, and the sulfur content ranges from 0.0045% to 0.005%, reducing the impact of harmful impurities and the formation of non-metallic inclusions; and the trace additions of chromium, nickel, and copper (0.04% to 0.05%, 0.001% to 0.002%, and 0.001% to 0.002%, respectively) further enhance the wire's corrosion resistance and weldability. This optimized combination of components results in the final steel strand possessing higher tensile strength, improved toughness, and superior corrosion resistance, better meeting the stringent requirements of applications such as bridge cables, prestressed concrete structures, mine supports, and marine engineering. After the wire rod is confirmed, non-destructive testing is performed to ensure that the quality of the wire rod meets the standards.

[0030] S2 first water washing, pickling, second water washing Next, use a high-pressure water gun to rinse the dust on the surface of the wire rod with hot water at a temperature of not less than 80°C, with a cleaning pressure of 5MPa or above. Then, open the wire rod and immerse it in a hydrochloric acid pickling tank for 10-15 minutes to remove surface oxides and oil stains. The corrosion inhibitor benzotriazole can be added to the pickling tank at a concentration of 0.1-0.3wt% to reduce excessive corrosion of the acid on the steel wire matrix. After pickling, use a high-pressure water gun to rinse the residual acid on the surface of the steel wire with hot water at a temperature of not less than 80°C, followed by hot air drying at a temperature of 80°C-100°C. High-pressure washing can completely remove residual acid and avoid secondary corrosion of the steel wire. High-temperature water washing and hot air drying can quickly evaporate water and prevent rust, thereby ensuring the cleanliness and flatness of the steel wire surface, laying a good foundation for subsequent drawing and galvanizing processes.

[0031] S3 drawing after washing and semi-finished product inspection The center wire is drawn from 15.0mm wire rod to 7.67mm in nine passes, the inner wire is drawn from 15.0mm wire rod to 7.36mm in nine passes, the outer thick wire is drawn from 15.0mm wire rod to 8.00mm in eight passes, and the outer thin wire is drawn from 15.0mm wire rod to 6.00mm in 11 passes. During each drawing process, the surface quality and dimensional accuracy of the steel wire are monitored to ensure that the specified diameter and surface roughness are achieved. The center wire, inner wire, outer thick wire, and outer thin wire are each drawn in multiple passes to the preset diameter, making the internal structure of the steel strand more compact and improving the overall strength and tensile properties of the steel strand. Furthermore, the transition dimensions of each wire are precisely controlled to ensure uniformity and consistency during the subsequent galvanizing and stranding processes, thereby improving product quality and stability.

[0032] S4-a1 aid plating The flux comprises the following components by weight: 1.91%-1.92% zinc chloride, 0.50%-0.51% sodium chloride, 0.34%-0.35% sodium fluoride, 0.59%-0.60% surfactant Fc (a composite surfactant formed by a mixture of fluorine-carbon and carbon-hydrogen chain surfactants), and the remainder water. The flux improves the adhesion and uniformity of the zinc coating and reduces porosity. The specific composition of the flux effectively enhances the cleanliness and wettability of the steel wire surface, thereby improving the quality of the subsequent zinc coating. Specifically, the combination of zinc chloride, sodium chloride, and sodium fluoride helps remove microscopic impurities from the steel wire surface and strengthens the bonding between the zinc solution and the steel wire substrate. The addition of surfactant Fc (a composite surfactant formed by a mixture of fluorine-carbon and carbon-hydrogen chain surfactants) further reduces interfacial tension and promotes uniform distribution of the zinc solution on the steel wire surface, resulting in a denser and more uniform zinc coating. This not only improves the adhesion of the coating but also enhances the overall corrosion resistance and mechanical properties of the steel strand.

[0033] S4-a2 hot dip galvanizing The steel wire is immersed in a zinc bath for 5-8 seconds. The chemical composition of the zinc bath includes Al: 0.17%-0.20%, Ni: 0.12%-0.25%, Sn: 0.30%-0.50%, Sr: 0.05%-0.45%, Bi: 0.12%-0.25%, Pb: 0.12%-0.22%, Sb: 0.04%-0.06%, and Fe: 0.02%-0.05%. The remainder is Zn and unavoidable impurities. The zinc coating is applied at a rate of 290g / m²-350g / m². After galvanizing, mist cooling is used to rapidly solidify the coating. The nitrogen pressure used for mist cooling is 0.3MPa-0.5MPa. This step effectively improves the density and corrosion resistance of the coating. The special chemical composition ratio of the zinc bath during the hot-dip galvanizing process significantly improves the density and adhesion of the coating, enhancing the corrosion resistance of the steel strand. Furthermore, the zinc coating is controlled within a range of 290g / m² to 350g / m², ensuring a coating thickness of 0.040mm to 0.049mm, further enhancing the steel strand's corrosion resistance and tensile strength. Mist cooling utilizes nitrogen at a pressure of 0.3MPa to 0.5MPa to accelerate the coating solidification process, prevent surface defects, and ensure coating quality and stability. These measures work together to ensure the steel strand not only possesses excellent corrosion resistance but also maintains excellent mechanical properties over time in harsh environments.

[0034] S4-a3 drawing after plating The center wire is drawn to 7.71mm after plating, the inner wire to 7.40mm after plating, the outer thick wire to 8.04mm after plating, and the outer thin wire to 6.04mm after plating. Post-plating drawing further optimizes the microstructure of the steel wire, improving tensile strength and ductility while reducing dimensional variations caused by plating thickness.

[0035] S5 twist 19 galvanized steel wires are twisted in layers in a 1+6+12 configuration. The spacing between the outer thick and thin wires is 0.16mm, and the spacing between the inner wires is 0.17mm. The outer wires are laid in a right-hand direction, with a lay length of 12.5 times the nominal diameter of the strand. During twisting, tension sensors monitor the tension of each wire in real time, limiting deviation to no more than 5%. This process ensures the strand's compact structure and stable mechanical properties.

[0036] S6 stabilization process The tempering temperature is 405-415°C, the production line speed is less than 9m / min, and the strand tension is controlled at 30%-35% of the strand's threshold force. Cooling after tempering uses a direct immersion cooling method, which helps eliminate residual stress and improves the strand's fatigue life.

[0037] S7 layer winding and finished product inspection The stabilized strands are wound into coils and subjected to comprehensive quality inspections, including cross-sectional dimensions (the upper tolerance for the nominal diameter of finished ultra-high-capacity strands is +0.40mm, the lower tolerance is -0.15mm, the center wire diameter is 7.71mm, the inner wire diameter is 7.40mm, the outer thick wire diameter is 8.04mm, and the outer thin wire diameter is 6.04mm). Furthermore, the coating adhesion is tested online (cross-hatch test, coating loss area ≤5%), the strand breaking load (≥260kN), and the elongation (≥3.5%) are tested. Qualified products proceed to the next stage.

[0038] S8 official test Samples were sent to a third-party authoritative organization for official testing to verify that all performance indicators met national standards and technical specifications. The ultra-high-force steel strand produced by the method for producing ultra-high-force steel strand provided in the embodiments of this application was tested by the Beijing Anchor Product Quality Supervision and Inspection Center of the Coal Industry. The inspection was based on GB / T 5224-2014 "Steel Strand for Prestressed Concrete," with a model specification of 1×19W-34.60-1970 and a sample number of 20232509601-06. The specific results are shown in Table 1.

[0039] Inspection Report Form 1

[0040] S9 packaging and warehousing Finally, the strands that have passed official testing are packaged and stored in a warehouse for shipment.

[0041] Example 2 Example 2 is the same as Example 1 in S1-S2, S5-S7 and S9 The difference is that Example 2 discloses a method for making an ultra-high-strength steel strand, comprising: S3 drawing after washing and semi-finished product inspection The center wire is drawn from 15.0mm wire rod to 7.71mm in nine passes, the inner wire is drawn from 15.0mm wire rod to 7.40mm in nine passes, the outer thick wire is drawn from 15.0mm wire rod to 8.04mm in eight passes, and the outer thin wire is drawn from 15.0mm wire rod to 6.04mm in 11 passes. During each drawing process, the surface quality and dimensional accuracy of the steel wire are monitored to ensure that the specified diameter and surface roughness are achieved. The center wire, inner wire, outer thick wire, and outer thin wire are each drawn in multiple passes to the preset diameter, making the internal structure of the steel strand more compact and improving the overall strength and tensile properties of the steel strand. Furthermore, precise control of the final dimensions of each wire ensures uniformity and consistency during the subsequent galvanizing and stranding processes, thereby enhancing product quality and stability.

[0042] S4-b1 phosphating The phosphating process temperature is not less than 80℃, and the drying time is ≥0.2min. The phosphating process forms a dense, uniform and strong phosphating film on the surface, thereby improving the corrosion resistance of the surface of the finished steel strand and meeting the lubrication, rust prevention and corrosion resistance requirements of the steel strand.

[0043] S8 official test Samples were sent to a third-party authoritative organization for official testing to verify that all performance indicators met national standards and technical specifications. The ultra-high-force steel strand produced by the method for producing ultra-high-force steel strand provided in the embodiments of this application was tested by the Beijing Anchor Product Quality Supervision and Inspection Center of the Coal Industry. The inspection was based on GB / T 5224-2014 "Steel Strand for Prestressed Concrete," with a model specification of 1×19W-34.60-1770 and a sample number of 20232509701-06. The specific results are shown in Table 2.

[0044] Inspection Report Form 2

[0045] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for manufacturing an ultra-high-force steel strand, wherein the ultra-high-force steel strand adopts a 1×19 wire rope structure and has a nominal diameter of 34.60 mm, characterized in that: The following steps are involved: S1, wire rod selection and wire rod testing experiment; S2, first water washing, acid washing, second water washing; S3, drawing after washing and semi-finished product inspection; S4, surface treatment; S5, twisted strands; S6, stabilization treatment; S7, layer winding and finished product inspection, where the upper deviation of the nominal diameter of the finished product of the ultra-high-force steel strand is +0.40mm, the lower deviation of the nominal diameter is -0.15mm, the center wire diameter is 7.71mm, the inner wire diameter is 7.40mm, the outer thick wire diameter is 8.04mm, and the outer thin wire diameter is 6.04mm; S8, official test; S9, packaging and storage.

2. The method for producing an ultra-high-force steel strand according to claim 1, wherein: In the selection of the wire rod in S1, wire rods of the same brand and specification are selected, and their chemical composition meets the following requirements: C: 0.84-0.860%, Si: 0.75-0.79%, Mn: 0.72-0.74%, P: 0.008-0.012%, S: 0.0045-0.005%, Cr: 0.04-0.05%, Ni: 0.001-0.002%, Cu: 0.001-0.002%, and the rest are Fe and unavoidable impurity elements.

3. The method for manufacturing the ultra-high-force steel strand according to claim 1, wherein: In the first water washing in S2, a high-pressure water gun is used to wash away dust on the surface of the wire rod with water of not less than 80°C. In the pickling in S2, the wire rod is opened and immersed in a hydrochloric acid pickling tank for 10-15 minutes to remove surface oxides and oil stains. After pickling, in the second water washing in S2, a high-pressure water gun is used to wash away residual acid on the surface of the steel wire with water of not less than 80°C. The washing pressure is 5MPa or above, and then hot air drying is performed. The temperature of the hot air drying is 80°C-100°C.

4. The ultra-high-force steel strand according to claim 3, characterized in that: During the pickling in S2, a corrosion inhibitor, benzotriazole, is added to the pickling tank at a concentration of 0.1-0.3 wt%.

5. The method for manufacturing the ultra-high-force steel strand according to claim 1, characterized in that: In the post-wash drawing in S3, the center wire is drawn from 15.0 mm wire rod to 7.67 mm through 9 passes, the inner layer wire is drawn from 15.0 mm wire rod to 7.36 mm through 9 passes, the outer layer thick wire is drawn from 15.0 mm wire rod to 8.00 mm through 8 passes, and the outer layer thin wire is drawn from 15.0 mm wire rod to 6.00 mm through 11 passes.

6. The method for manufacturing the ultra-high-force steel strand according to claim 5, characterized in that: The surface treatment in S4 includes the following steps: S4-a1 plating flux, the plating flux comprises the following components in parts by weight: 1.91%-1.92% zinc chloride, 0.50%-0.51% sodium chloride, 0.34%-0.35% sodium fluoride, 0.59%-0.60% surfactant Fc, and the remainder water; S4-a2 hot-dip galvanizing: immerse the steel wire in zinc solution for 5-8 seconds. The chemical composition of the zinc solution includes Al: 0.17%-0.20%, Ni: 0.12%-0.25%, Sn: 0.30%-0.50%, Sr: 0.05%-0.45%, Bi: 0.12%-0.25%, Pb: 0.12%-0.22%, Sb: 0.04%-0.06%, Fe: 0.02%-0.05%, and the rest are Zn and unavoidable impurity elements. The amount of zinc applied is 290g / m2-350g / m2. After galvanizing, mist cooling is used to quickly solidify the coating. The nitrogen pressure used for mist cooling is 0.3MPa-0.5MPa. S4-a3 is drawn after plating. The center wire is drawn to 7.71mm after plating, the inner wire is drawn to 7.40mm after plating, the outer thick wire is drawn to 8.04mm after plating, and the outer thin wire is drawn to 6.04mm after plating.

7. The method for manufacturing an ultra-high-force steel strand according to claim 1, characterized in that: In the post-wash drawing in S3, the center wire is drawn from 15.0 mm wire rod to 7.71 mm through 9 passes, the inner layer wire is drawn from 15.0 mm wire rod to 7.40 mm through 9 passes, the outer layer thick wire is drawn from 15.0 mm wire rod to 8.04 mm through 8 passes, and the outer layer thin wire is drawn from 15.0 mm wire rod to 6.04 mm through 11 passes.

8. The method for manufacturing the ultra-high-force steel strand according to claim 7, characterized in that: The surface treatment in S4 includes the following steps: S4-b1 phosphating, the phosphating process temperature is not less than 80℃, and the drying time is ≥0.2min. The phosphating process forms a layer of carrier on the surface, namely the phosphating film, which plays a role in lubrication and rust prevention.

9. The method for manufacturing an ultra-high-force steel strand according to claim 1, characterized in that: In the stranding of S5, 19 galvanized steel wires are twisted in layers according to a 1+6+12 structure. The distance between the outer thick wire and the outer thin wire is 0.16 mm, and the distance between the inner wires is 0.17 mm. The outer layer steel wires are twisted in the right direction, and the twist pitch is 12.5 times the nominal diameter of the steel strand. During twisting, the tension of each steel wire is monitored in real time by a tension sensor, and the control deviation does not exceed 5%; in the stabilization treatment of S6, the tempering temperature is 405~415℃, the production line operating speed is lower than 9m / min, the tension of the steel strand is controlled at 30%-35% of the threshold force of the steel strand, and the cooling after tempering adopts a direct cooling immersion cooling method.

10. The method for manufacturing an ultra-high-force steel strand according to claim 1, characterized in that: The nominal tensile strength of the ultra-high-force steel strand is in the range of 1770~1960MPa, corresponding to a maximum force of 1395kN~1699kN and a 0.2% yield strength of not less than 1310; the total elongation at maximum force is ≥3.5%.

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