A method for manufacturing a large-size steel wire strand using a steel bar with uniform performance

Abstract

This invention relates to the field of steel rolling technology and discloses a method for manufacturing large-diameter steel strand with uniform through-strand performance. The production process is as follows: heating of wire rod billet → high-pressure water descaling → roughing, intermediate rolling, finishing rolling and water tank controlled cooling → wire drawing → Stellmor air-cooled line controlled cooling → coiling → PF chain transportation → finishing. A segmented Stellmor air-cooled line controlled cooling is adopted, and staggered segmented cooling is achieved by adjusting the fan air volume, roller speed, opening angle of the Gailin device and opening / closing of the insulation cover. The first stage of controlled cooling temperature changes from 890±10℃ to 650±10℃, the second stage from 650±10℃ to 590±10℃, the third stage from 590±10℃ to 450±10℃, and the fourth stage from 450±10℃ to room temperature, followed by natural cooling. The method of this invention adopts a staged controlled cooling process of high-speed wire rolling and Stellmore air-cooling line with lower production costs, and controls the temperature of the wire rod during the air-cooling process to solve the problem of large fluctuations in wire rod performance.

Description

Technical Field

[0001] This invention relates to the field of steel rolling technology, and in particular to a method for manufacturing large-diameter steel strand with uniform through-strand properties. Background Technology

[0002] High-carbon steel wire is one of the typical steel grades among drawn products. It has high strength and toughness and is an important raw material for producing high-strength, large-diameter prestressed steel strands and high-strength, low-relaxation prestressed steel wires. It is widely used in public infrastructure, energy and marine engineering and other fields.

[0003] Currently, some steel companies are developing higher-strength products by upgrading equipment, such as adding lead baths, salt baths, and water baths, and developing ultra-fast cooling + isothermal martensitization treatment technology to obtain products with high martensitization rate, small performance fluctuations, and good strength-toughness matching. However, these equipment investments are huge, and they also increase production costs and the risk of environmental pollution. Currently, the controlled cooling process for high-carbon steel wire rods mostly uses the lower-cost Stellmore air-cooled line. The microstructure and properties control can fully meet the production requirements for raw materials for 1860MPa grade steel strands with a diameter of Φ21.8mm and below. Through chemical composition design and microalloying technology, it can also fully meet the production requirements for raw materials for 1960MPa grade steel strands with a diameter of Φ21.8mm and below. However, the drawback of the air-cooled controlled cooling process is that as the strength increases, the temperature difference between the head / middle / tail of the rolled material and the uneven cooling caused by the overlapping / non-overlapping positions make the fluctuation of its microstructure and mechanical properties more obvious. How to make use of the "residual heat" of the Stellmore air-cooled line, reasonably control and reduce the fluctuation of the wire rod spinning temperature and the key process parameters of the air-cooled line, and reduce the fluctuation of the wire rod performance are problems that need to be solved.

[0004] Therefore, there is a need in the existing technology to improve the steel used for large-diameter steel strands with uniform through-strand properties and the manufacturing method thereof. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a method for manufacturing large-diameter steel strand with uniform through-strand performance. This method employs a high-speed wire rolling process with lower production costs and a staged controlled cooling process using a Stellmore air-cooled wire to control the through-strand temperature of the wire during the air-cooling process, thereby solving the problem of large fluctuations in through-strand performance.

[0006] Based on the above objectives, embodiments of the present invention provide a method for manufacturing large-diameter steel strand with uniform through-strand properties. The production process is as follows: heating of wire rod billet → high-pressure water descaling → roughing, intermediate rolling, finishing rolling and water tank controlled cooling → wire drawing → Steyrmo air-cooled wire controlled cooling → coiling → PF chain transportation → finishing. The method employs segmented Steyrmo air-cooled wire controlled cooling, including:

[0007] The first stage of controlled cooling temperature variation is 890±10℃~650±10℃, the initial roller speed is 0.56~0.58m / s, and it is increased in increments of 0.04m / s. The maximum air volume of the fan is 200,000 m³ / s. 3 / h, opening degree 100%, wire splicing / non-splicing cooling rate is 8~10℃ / s, Jialing device opening angle is 3~5 degrees, heat preservation cover is open;

[0008] The second stage of controlled cooling temperature variation is 650±10℃~590±10℃, with the roller speed increasing by 0.02m / s in stages, and the maximum air volume of the fan is 155,000 m³ / s. 3 / h, opening degree is 90%~95%, wire overlap / non-overlap cooling rate is 3~5℃ / s, Jialing device opening angle is 0~2 degrees, heat preservation cover is open;

[0009] The third stage of controlled cooling temperature changes from 590±10℃ to 450±10℃, the roller speed increases by 0.01m / s in stages, the fan is turned off, the insulation cover is completely closed, and the cooling rate of the wire lap / non-lap is 1~2℃ / s.

[0010] The fourth stage involves controlling the cooling temperature to vary from 450±10℃ to room temperature, followed by natural cooling.

[0011] In some embodiments, the chemical composition of the steel strand wire, by weight percentage, includes: C 0.84%–0.87%, Si 0.50%–0.60%, Mn 0.60%–0.80%, P ≤0.015%, S ≤0.010%, Cr 0.25%–0.35%, Cu ≤0.20%, Ni ≤0.10%, with the remainder being Fe and unavoidable impurities.

[0012] In some implementations, the carbon segregation at the center of the blank used for the wire is ≤1.10.

[0013] In some implementations, during the heating stage of the wire rod billet, the soaking temperature is 1080-1150℃, and the heating time is t=(0.7-1.2)H, where H is the thickness of the billet in mm and the heating time t is in min.

[0014] In some implementations, the dephosphorization water pressure is 15–20 MPa during the high-pressure water dephosphorization stage.

[0015] In some implementations, during the rolling and water tank cooling stages, the temperature difference along the length of the workpiece after the fourth stand of the roughing mill is controlled to be ≤20℃, and the temperature before final rolling is 870±10℃.

[0016] In some implementations, the opening degree of the water tank before final rolling is ≥25%, and the water inflow into the water tank is ≥50m³. 3 / h, outlet water pressure ≥3.5 bar, water tank opening degree after final rolling ≤5%.

[0017] In some implementations, the spinning temperature is controlled at 890±10℃, and the temperature difference along the entire length of the wire is ≤10℃.

[0018] In some implementations, the spinning machine has an inclination angle of 20°, a vibration value of ≤0.5mm / s, and a spinning speed of 29-31m / s.

[0019] In some implementations, a walking beam furnace is used to heat the billet.

[0020] The present invention has at least the following beneficial technical effects:

[0021] Employing a lower-cost high-speed wire rolling + Stellmore air-cooled controlled-line cooling process, this technology achieves staggered segmented cooling by adjusting fan airflow, roller speed, the opening angle of the Galing device, and the opening / closing of the insulation cover. Through chemical composition design and temperature control of the wire rod during rolling and air cooling processes, the problem of large fluctuations in wire rod performance is solved. Its high-carbon steel wire rod can meet the production requirements of Φ21.8mm specification and 1960MPa strength grade steel strand. The process is simple to operate, has low production cost, and is easy to promote and apply industrially. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples.

[0023] The terms "comprising" and "having," and any variations thereof, in the specification and claims of this invention are intended to cover non-exclusive inclusion; the terms "first," "second," etc., in the specification and claims of this invention are used to distinguish different objects, not to describe a particular order. "A plurality of" means two or more, unless otherwise explicitly specified.

[0024] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] This invention provides a method for manufacturing large-diameter steel strand with uniform properties. The production process is as follows: heating of wire rod billet → high-pressure water descaling → roughing, intermediate rolling, finishing rolling and water tank controlled cooling → wire drawing → controlled cooling on the Steyrmo air-cooling line → coiling → PF chain transportation → finishing. The Steyrmo air-cooling line uses segmented controlled cooling: uniform cooling of the wire rod and reasonable control of its microstructure and properties are achieved by adjusting the speed of the rollers before and after the drop section, the opening angle of the galvanizing device, the opening degree of the fan, and the opening / closing of the insulation cover. Specifically, it includes the following stages:

[0026] The first stage of controlled cooling temperature variation is 890±10℃~650±10℃, the initial roller speed is 0.56~0.58m / s, and it is increased in increments of 0.04m / s. The maximum air volume of the fan is 20.0m³ / s. 3 / h, opening degree 100%, wire splicing / non-splicing cooling rate is 8~10℃ / s, Jialing device opening angle is 3~5 degrees, heat preservation cover is open;

[0027] The second stage of controlled cooling temperature variation is 650±10℃~590±10℃, with the roller speed increasing by 0.02m / s in stages, and the maximum air volume of the fan is 155,000 m³ / s. 3 / h, opening degree is 90%~95%, wire overlap / non-overlap cooling rate is 3~5℃ / s, Jialing device opening angle is 0~2 degrees, heat preservation cover is open;

[0028] The third stage of controlled cooling temperature changes from 590±10℃ to 450±10℃, the roller speed increases by 0.01m / s in stages, the fan is turned off, the insulation cover is completely closed, and the cooling rate of the wire lap / non-lap is 1~2℃ / s.

[0029] The fourth stage involves controlling the cooling temperature to vary from 450±10℃ to room temperature, followed by natural cooling.

[0030] Furthermore, the chemical composition of the steel strand wire by weight percentage is as follows: C 0.84%~0.87%, Si 0.50%~0.60%, Mn 0.60%~0.80%, P≤0.015%, S≤0.010%, Cr 0.25%~0.35%, Cu≤0.20%, Ni≤0.10%; the remainder is Fe and unavoidable impurities.

[0031] Furthermore, the rolled billet: the carbon segregation degree at the center of the billet used for steel strand wire rod is ≤1.10.

[0032] Further, billet heating: the soaking temperature is 1080~1150℃, and the heating time is t=(0.7~1.2)H, where H is the billet thickness in mm and the heating time t is in min.

[0033] Furthermore, high-pressure water dephosphorization: the dephosphorization water pressure is 15-20 MPa, and there should be no visible residual iron oxide scale on the surface of the billet after dephosphorization.

[0034] Furthermore, in the roughing, intermediate, and finishing rolling processes and the water tank controlled cooling process, the temperature difference along the length of the rolled piece after the fourth stand of the roughing mill is controlled at ≤20℃; the water tank opening degree before the final rolling is ≥25%, and the water inlet volume is ≥50m³. 3 / h, outlet water pressure ≥3.5 bar, temperature before final rolling is 870±10℃; water tank opening degree after final rolling ≤5%.

[0035] Furthermore, in the spinning process, the spinning temperature is controlled at 890±10℃, and the temperature difference along the entire length of the wire is ≤10℃; the inclination angle of the spinning machine is 20°, the vibration value of the spinning machine is ≤0.5mm / s, and the spinning speed is 29~31m / s to ensure stable coil shape.

[0036] The high-carbon steel wire produced by the above method, when the same coil of wire is cut into 8 segments, has a tensile strength difference of ≤30MPa within the same coil, a tensile strength difference of ≤40MPa for the whole strand, a sorbitization rate of ≥90%, a core network cementite of ≤1.0 grade, no core martensitic quenching structure, and a finished steel strand strength of 1990~2050MPa.

[0037] The present invention will be further explained below with reference to specific embodiments.

[0038] Example 1

[0039] A metal products company uses the technology of this invention to produce high carbon steel strand with a specification of Φ14.0mm. The production process is as follows: billet heating → high pressure water descaling → roughing, intermediate and finishing rolling and water tank cooling → wire drawing → Steyrmo air cooling line cooling → coiling → PF chain transportation → finishing.

[0040] The chemical composition of the steel strand wire by weight percentage is as follows: C 0.84%, Si 0.60%, Mn 0.71%, P 0.012%, S 0.008%, Cr 0.28%, Cu 0.04%, Ni 0.03%, with the remainder being Fe and unavoidable impurities.

[0041] The carbon segregation degree at the center of the billet used for steel strand is 1.08.

[0042] The raw material was placed in a walking beam furnace for heating. The temperature of the soaking zone was 1130℃, the billet thickness was 200mm, and the heating time was 210min.

[0043] After exiting the furnace, the hot billet is subjected to high-pressure water dephosphorization at a pressure of 18 MPa. No iron oxide scale residue is visible on the surface after dephosphorization.

[0044] The temperature difference along the length of the workpiece after the fourth stand of the roughing mill is 18℃. Before the final rolling, the opening degrees of water tanks #1 to #4 are 25%, 28%, 28%, and 30%, respectively, and the water inflow rates of the tanks are 50, 55, 55, and 55 m³, respectively. 3 / h, outlet water pressure is 3.5, 3.8, 3.8, 4.0 bar; temperature before final rolling is 873℃; after final rolling, the opening degree of No. 5 water tank is 3%, the wire drawing temperature is 887℃, and the temperature difference along the entire length of the wire is 8℃.

[0045] Hot-rolled wire is continuously and evenly laid on a moving roller conveyor via a wire spinner. The wire spinner has an inclination angle of 20°, a vibration value of 0.4 mm / s, a spinning speed of 29 m / s, a coil diameter of 1075 mm, and a stable coil shape.

[0046] The total length of the air-cooled line is 105 meters. The air-cooled roller conveyor is divided into 13 sections. The first section of the roller conveyor is relatively short and has no fan installed underneath. Each of the remaining sections has two fans installed underneath. Each fan has a Jialing device to adjust the air volume ratio between the overlapping and non-overlapping positions of the line. There are a total of 8 drop sections after sections 3, 4, 5, 6, 7, 9, 11, and 12 of the air-cooled roller conveyor.

[0047] The controlled cooling process for hot-rolled wire rods employs a Stellmore-style segmented air-cooling system.

[0048] (1) 887℃-649℃, from the beginning of the first stage to the end of the third stage, the initial roller speed is 0.56m / s, and the roller speed increases by 0.04m / s in each stage. The maximum air volume of the fan is 200,000 m³ / s. 3 / h, the opening angle of the Jialing device under the fan is 3°, the opening degree of fans 1#-4# is 100%, the insulation cover is fully opened, and the cooling rates of wire lapped / non-lapped are 8℃ / s and 10℃ / s respectively;

[0049] (2) 649℃-588℃, from the beginning of the 4th stage to the 5th stage, the roller speed at the end of the 3rd stage is 0.68m / s, and the roller speed increases by 0.02m / s in each stage. The maximum air volume of fans 5# and 6# is 200,000 m3 / h, and the maximum air volume of fan 7# is 155,000 m3 / h. 3 / h, the opening angle of the Jialing device below the fan is 2°, the opening degree of fans 5#-6# is 95%, the opening degree of fan 7# is 90%, the insulation cover is fully opened, and the cooling rates of wire lap / non-lap are 3℃ / s and 4℃ / s respectively;

[0050] (3) 588℃-450℃, from the middle and end of the 5th section to the end of the 13th section, the roller speed at the end of the 5th section is 0.7m / s, the roller speed increases by 0.01m / s in each section, all fans are turned off, all insulation covers are turned off, and the cooling speed of the wire lap / non-lap is 1℃ / s.

[0051] (4) Then roll it up and let it cool naturally.

[0052] The high-carbon steel wire produced using the above method was analyzed by taking one coil from the beginning, middle, and end. Each coil was cut into eight equal parts. The tensile strength difference within the same coil was 25 MPa, and the tensile strength difference of the entire strand was 38 MPa. The sorbitization rate was 92%, the network cementite was grade 1.0, and the core martensite was grade 0.5. The tensile strength of the Φ21.8mm steel strand produced in this furnace ranged from 1190 to 2025 MPa, with minimal fluctuation in the steel strand performance.

[0053] Example 2

[0054] A metal products company uses the technology of this invention to produce high carbon steel strand with a specification of Φ14.0mm. The production process is as follows: billet heating → high pressure water descaling → roughing, intermediate and finishing rolling and water tank cooling → wire drawing → Steyrmo air cooling line cooling → coiling → PF chain transportation → finishing.

[0055] The chemical composition of the steel strand wire by weight percentage is as follows: C 0.87%, Si 0.50%, Mn 0.60%, P 0.015%, S 0.010%, Cr 0.25%, Cu 0.04%, Ni 0.03%, with the remainder being Fe and unavoidable impurities.

[0056] The carbon segregation degree at the center of the billet used for steel strand is 1.05.

[0057] The raw material was placed in a walking beam furnace for heating. The temperature of the soaking zone was 1150℃, the thickness of the billet was 200mm, and the heating time was 240min.

[0058] After being taken out of the furnace, the hot billet is subjected to high-pressure water dephosphorization at a pressure of 20 MPa. No iron oxide scale residue is visible on the surface after dephosphorization.

[0059] The temperature difference along the length of the workpiece after the fourth stand of the roughing mill is 10℃. Before the final rolling, the opening degrees of water tanks #1 to #4 are 25%, 28%, 28%, and 30%, respectively, and the water inflow rates of the tanks are 50, 55, 55, and 55 m³, respectively. 3 / h, outlet water pressure is 3.5, 3.8, 3.8, 4.0 bar; temperature before final rolling is 860℃; after final rolling, the opening degree of No. 5 water tank is 1%, the wire drawing temperature is 888℃, and the temperature difference along the entire length of the wire is 10℃.

[0060] Hot-rolled wire is continuously and evenly laid on a moving roller conveyor via a wire drawing machine. The wire drawing machine has an inclination angle of 20°, a vibration value of 0.2 mm / s, a drawing speed of 30 m / s, a coil diameter of 1075 mm, and a stable coil shape.

[0061] The total length of the air-cooled line is 105 meters. The air-cooled roller conveyor is divided into 13 sections. The first section of the roller conveyor is relatively short and has no fan installed underneath. Each of the remaining sections has two fans installed underneath. Each fan has a Jialing device to adjust the air volume ratio between the overlapping and non-overlapping positions of the line. There are a total of 8 drop sections after sections 3, 4, 5, 6, 7, 9, 11, and 12 of the air-cooled roller conveyor.

[0062] The controlled cooling process for hot-rolled wire rods employs a Stellmore-style segmented air-cooling system.

[0063] (1) 888℃-650℃, from the beginning of the first stage to the end of the third stage, the initial roller speed is 0.56m / s, the roller speed increases by 0.04m / s in each stage, the maximum air volume of the fan is 200,000 m3 / h, the opening angle of the Jialing device below the fan is 5°, the opening degree of the 1#-4# fans is 100%, the heat insulation cover is fully opened, and the cooling speed of the wire overlap / non-overlap is 8℃ / s and 9℃ / s respectively;

[0064] (2) 650℃-591℃, from the beginning of the 4th section to the middle of the 5th section, the roller speed at the end of the 3rd section is 0.68m / s, the roller speed increases by 0.02m / s in each section, the maximum air volume of the 5#-6# fan is 200,000 m3 / h, the maximum air volume of the 7# fan is 155,000 m3 / h, the opening angle of the Jialing device below the fan is 2°, the opening degree of the 5#-6# fan is 95%, the opening degree of the 7# fan is 90%, the insulation cover is fully opened, and the cooling speed of the wire overlap / non-overlap is 3℃ / s and 3℃ / s respectively;

[0065] (3) 591℃-440℃, from the middle and end of the 5th section to the end of the 13th section, the roller speed at the end of the 5th section is 0.7m / s, the roller speed increases by 0.01m / s in each section, all fans are turned off, all insulation covers are turned off, and the cooling speed of the wire lap / non-lap is 2℃ / s.

[0066] (4) Then roll it up and let it cool naturally.

[0067] The high-carbon steel wire produced using the above method was analyzed by taking one coil from the beginning, middle, and end. Each coil was cut into eight equal parts. The tensile strength difference within the same coil was 30 MPa, and the tensile strength difference of the entire strand was 40 MPa. The sorbitization rate was 95%, the network cementite was grade 1.0, and the core martensite was grade 0. The tensile strength of the Φ21.8 mm steel strand produced by this furnace ranged from 2019 to 2050 MPa, with minimal fluctuation in the steel strand performance.

[0068] Example 3

[0069] A metal products company uses the technology of this invention to produce high carbon steel strand with a specification of Φ14.0mm. The production process is as follows: billet heating → high pressure water descaling → roughing, intermediate and finishing rolling and water tank cooling → wire drawing → Steyrmo air cooling line cooling → coiling → PF chain transportation → finishing.

[0070] The chemical composition of the steel strand wire by weight percentage is as follows: C 0.85%, Si 0.55%, Mn 0.80%, P 0.008%, S 0.008%, Cr 0.35%, Cu 0.05%, Ni 0.03%, with the remainder being Fe and unavoidable impurities.

[0071] The carbon segregation at the center of the billet used for steel strand is 1.10.

[0072] The raw material was placed in a walking beam furnace for heating. The temperature of the soaking zone was 1100℃, the thickness of the billet was 200mm, and the heating time was 180min.

[0073] After exiting the furnace, the hot billet is subjected to high-pressure water dephosphorization at a pressure of 15 MPa. No iron oxide scale residue is visible on the surface after dephosphorization.

[0074] The temperature difference along the length of the workpiece after the fourth stand of the roughing mill is 15℃. Before the final rolling, the opening degrees of water tanks #1 to #4 are 25%, 28%, 28%, and 30%, respectively, and the water inflow rates of the tanks are 50, 55, 55, and 55 m³, respectively. 3 / h, outlet water pressure is 3.5, 3.8, 3.8, 4.0 bar; temperature before final rolling is 880℃; after final rolling, the opening degree of No. 5 water tank is 5%, the wire drawing temperature is 892℃, and the temperature difference along the entire length of the wire is 8℃.

[0075] Hot-rolled wire is continuously and evenly laid on a moving roller conveyor via a wire spinner. The wire spinner has an inclination angle of 20°, a vibration value of 0.4 mm / s, a spinning speed of 29 m / s, a coil diameter of 1075 mm, and a stable coil shape.

[0076] The total length of the air-cooled line is 105 meters. The air-cooled roller conveyor is divided into 13 sections. The first section of the roller conveyor is relatively short and has no fan installed underneath. Each of the remaining sections has two fans installed underneath. Each fan has a Jialing device to adjust the air volume ratio between the overlapping and non-overlapping positions of the line. There are a total of 8 drop sections after sections 3, 4, 5, 6, 7, 9, 11, and 12 of the air-cooled roller conveyor.

[0077] The controlled cooling process for hot-rolled wire rods employs a Stellmore-style segmented air-cooling system.

[0078] (1) 892℃-655℃, from the beginning of the first stage to the end of the third stage, the initial roller speed is 0.56m / s, and the roller speed increases by 0.04m / s in each stage. The maximum air volume of the fan is 200,000 m³ / s. 3 / h, the opening angle of the Jialing device under the fan is 4°, the opening degree of fans 1#-4# is 100%, the insulation cover is fully opened, and the cooling rates of wire lapped / non-lapped are 9℃ / s and 9℃ / s respectively;

[0079] (2) 655℃-578℃, from the beginning of the 4th section to the 5th section, the roller speed at the end of the 3rd section is 0.68m / s, and the roller speed increases by 0.02m / s in each section. The maximum air volume of the 5#-6# fans is 200,000 m³ / s. 3 / h, the maximum air volume of fan #7 is 155,000 m3 / h, the opening angle of the Jialing device below the fan is 1°, the opening degree of fans #5-6 is 95%, the opening degree of fan #7 is 90%, the insulation cover is fully open, and the cooling rates of wire lap / non-lap are 3℃ / s and 4℃ / s respectively.

[0080] (3) 578℃-451℃, from the middle and end of the 5th section to the end of the 13th section, the roller speed at the end of the 5th section is 0.7m / s, the roller speed increases by 0.01m / s in each section, all fans are turned off, all insulation covers are turned off, the cooling speed of the wire overlap is 1℃ / s, and the cooling speed of the non-overlap is 2℃ / s.

[0081] (4) Then roll it up and let it cool naturally.

[0082] The high-carbon steel wire produced using the above method was analyzed by taking one coil from the beginning, middle, and end. Each coil was cut into eight equal parts. The tensile strength difference within the same coil was 20 MPa, and the tensile strength difference of the entire strand was 39 MPa. The sorbitization rate was 93%, the network cementite was grade 0, and the core martensite was grade 0.5. The tensile strength of the Φ21.8mm steel strand produced in this furnace ranged from 2002 to 2038 MPa, with minimal fluctuation in the steel strand performance.

[0083] Example 4

[0084] A metal products company uses the technology of this invention to produce high carbon steel strand with a specification of Φ14.0mm. The production process is as follows: billet heating → high pressure water descaling → roughing, intermediate and finishing rolling and water tank cooling → wire drawing → Steyrmo air cooling line cooling → coiling → PF chain transportation → finishing.

[0085] The chemical composition of the wire rod for steel strand is as follows (by weight percentage): C 0.86%, Si 0.52%, Mn 0.75%, P 0.011%, S 0.009%, Cr 0.30%, Cu 0.04%, Ni 0.03%, with the remainder being Fe and unavoidable impurities.

[0086] The carbon segregation degree at the center of the billet used for steel strand is 1.09.

[0087] The raw material was placed in a walking beam furnace for heating. The temperature of the soaking zone was 1080℃, the billet thickness was 200mm, and the heating time was 140min.

[0088] After exiting the furnace, the hot billet is subjected to high-pressure water dephosphorization at a pressure of 16 MPa. No iron oxide scale residue is visible on the surface after dephosphorization.

[0089] The temperature difference along the length of the workpiece after the fourth stand of the roughing mill is 20℃. Before the final rolling, the opening degrees of water tanks #1 to #4 are 25%, 28%, 28%, and 30%, respectively, and the water inflow rates of the tanks are 50, 55, 55, and 55 m³, respectively. 3 / h, outlet water pressure is 3.5, 3.8, 3.8, 4.0 bar; temperature before final rolling is 870℃; after final rolling, the opening degree of water tank #5 is 0%, the wire drawing temperature is 900℃, and the temperature difference along the entire length of the wire is 10℃.

[0090] Hot-rolled wire is continuously and evenly laid on a moving roller conveyor via a wire spinner. The wire spinner has an inclination angle of 20°, a vibration value of 0.5 mm / s, a spinning speed of 31 m / s, a coil diameter of 1075 mm, and a stable coil shape.

[0091] The total length of the air-cooled line is 105 meters. The air-cooled roller conveyor is divided into 13 sections. The first section of the roller conveyor is relatively short and has no fan installed underneath. Each of the remaining sections has two fans installed underneath. Each fan has a Jialing device to adjust the air volume ratio between the overlapping and non-overlapping positions of the line. There are a total of 8 drop sections after sections 3, 4, 5, 6, 7, 9, 11, and 12 of the air-cooled roller conveyor.

[0092] The controlled cooling process for hot-rolled wire rods employs a Stellmore-style segmented air-cooling system.

[0093] (1) 900℃-660℃, from the beginning of the first stage to the end of the third stage, the initial roller speed is 0.56m / s, and the roller speed increases by 0.04m / s in each stage. The maximum air volume of the fan is 200,000 m³ / s. 3 / h, the opening angle of the Jialing device under the fan is 3°, the opening degree of fans 1#-4# is 100%, the insulation cover is fully opened, and the cooling rates of wire lapped / non-lapped are 9℃ / s and 10℃ / s respectively;

[0094] (2) 660℃-600℃, from the beginning of the 4th section to the 5th section, the roller speed at the end of the 3rd section is 0.68m / s, and the roller speed increases by 0.02m / s in each section. The maximum air volume of the 5#-6# fans is 200,000 m³ / s. 3 / h, the maximum air volume of fan #7 is 155,000 m³ / h. 3 / h, the opening angle of the Jialing device below the fan is 0°, the opening degree of fans 5#-6# is 95%, the opening degree of fan 7# is 90%, the insulation cover is fully opened, and the cooling rates of wire lap / non-lap are 4℃ / s and 5℃ / s respectively.

[0095] (3) 600℃-460℃, from the middle and end of the 5th section to the end of the 13th section, the roller speed at the end of the 5th section is 0.7m / s, the roller speed increases by 0.01m / s in each section, all fans are turned off, all insulation covers are turned off, and the cooling rate of the wire lap / non-lap is 1℃ / s.

[0096] (4) Then roll it up and let it cool naturally.

[0097] The high-carbon steel wire produced using the above method was analyzed by taking one coil from the beginning, middle, and end. Each coil was cut into eight equal parts. The tensile strength difference within the same coil was 30 MPa, and the tensile strength difference of the entire strand was 39 MPa. The sorbitization rate was 90%, the network cementite was grade 1.0, and the core martensite was grade 0.5. The tensile strength of the Φ21.8mm steel strand produced by this furnace ranged from 2012 to 2046 MPa, with minimal fluctuation in the steel strand performance.

[0098] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0099] It should be understood that, as used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, “and / or” refers to any and all possible combinations of one or more of the associated listed items.

[0100] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0101] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for manufacturing large-diameter steel strand with uniform through-strand properties, comprising the following production process: heating of wire rod billet → high-pressure water descaling → roughing, intermediate rolling, finishing rolling and water tank controlled cooling → wire drawing → Steyrmo air-cooled wire controlled cooling → coiling → PF chain transport → finishing, characterized in that, The system employs a segmented Stellmo air-cooled linear cooling system, including: The first stage temperature change of controlled cooling is 890±10℃~650±10℃, the initial roller speed is 0.56~0.58m / s, which is increased by 0.04m / s step by step, the maximum air volume of the fan is 200,000m 3 / h, the opening degree is 100%, the cooling speed of the wire lapping / non-lapping position is 8~10℃ / s, the opening angle of the Jialing device is 3~5 degrees, and the heat preservation cover is opened. The second stage of controlled cooling temperature variation is 650±10℃~590±10℃, with the roller speed increasing by 0.02m / s in stages, and the maximum air volume of the fan is 155,000 m³ / s. 3 / h, opening degree is 90%~95%, cooling rate of wire splice / non-splice position is 3~5℃ / s, Jialing device opening angle is 0~2 degrees, heat preservation cover is opened; The third stage of controlled cooling temperature changes from 590±10℃ to 450±10℃, the roller speed increases by 0.01m / s in stages, the fan is turned off, the insulation cover is completely closed, and the cooling rate of the wire overlap / non-overlap position is 1~2℃ / s. The fourth stage involves controlling the cooling temperature to 450±10℃ to room temperature, followed by natural cooling. The chemical composition of the steel strand wire, by weight percentage, includes: C: 0.84%–0.87%, Si: 0.50%–0.60%, Mn: 0.60%–0.80%, P≤0.015%, S≤0.010%, Cr 0.25%–0.35%, Cu≤0.20%, Ni≤0.10%, with the remainder being Fe and unavoidable impurities. Furthermore, the spinning temperature is controlled at 890±10℃, and the temperature difference along the entire length of the wire is ≤10℃.

2. The method for manufacturing large-diameter steel strand with uniform through-strand properties according to claim 1, characterized in that, The carbon segregation degree at the center of the blank used for the wire is ≤1.

10.

3. The method for manufacturing large-diameter steel strand with uniform through-strand properties according to claim 1, characterized in that, During the heating stage of the wire rod billet, the soaking temperature is 1080~1150℃, and the heating time is t=(0.7~1.2)H, where H is the thickness of the billet in mm and the heating time t is in min.

4. The method for manufacturing large-diameter steel strand with uniform through-strand properties according to claim 1, characterized in that, During the high-pressure water dephosphorization stage, the dephosphorization water pressure is 15-20 MPa.

5. The method for manufacturing large-diameter steel strand with uniform through-strand properties according to claim 1, characterized in that, During the rolling and water tank cooling stages, the temperature difference along the length of the workpiece after the fourth stand of the roughing mill is controlled at ≤20℃, and the temperature before final rolling is 870±10℃.

6. The method for manufacturing large-diameter steel strand with uniform through-strand properties according to claim 1, characterized in that, Before final rolling, the water tank opening degree should be ≥25%, and the water inlet volume should be ≥50m³. 3 / h, outlet water pressure ≥3.5 bar, water tank opening degree after final rolling ≤5%.

7. The method for manufacturing large-diameter steel strand with uniform through-strand properties according to claim 1, characterized in that, The spinning machine has an inclination angle of 20°, a vibration value of ≤0.5mm / s, and a spinning speed of 29~31m / s.

8. The method for manufacturing large-diameter steel strand with uniform through-strand properties according to claim 1, characterized in that, The billet is heated using a walking beam furnace.