A rolling and controlled cooling method for reducing net-like cementite of SWRH82B hot-rolled wire rod

Abstract

The present application belongs to the field of rolling and controlled cooling technology, and particularly relates to a rolling and controlled cooling method for reducing net-shaped cementite of SWRH82B hot-rolled wire rod. The present application is characterized in that: SWRH82B bloom is heated and rolled into a round bar through 24 passes; the round bar is water-cooled after rolling, and then is drawn into a required specification of loose coil wire rod; the wire rod is sequentially transported, air-cooled, coiled, air-cooled on a PF line, trimmed at head and tail, and packaged, thereby further reducing the net-shaped cementite of the existing 12.5mm SWRH82B hot-rolled wire rod for pre-stressed steel strand. That is, through integrated innovation of the controlled cooling process such as SWRH82B final rolling temperature, water cooling after rolling, drawing speed, drawing temperature, roller speed, fan air volume, air speed and the like, the wire rod same-circle metallographic structure and mechanical properties are effectively improved, the wire rod through-metallographic structure and mechanical properties are good, the wire rod wire-drawing interruption phenomenon is avoided, and the user's use requirement is better met.

Description

Technical Field

[0001] This invention belongs to the field of rolling cooling technology, specifically relating to a rolling cooling method for reducing the network cementite in SWRH82B hot-rolled wire rod. Background Technology

[0002] Currently, SWRH82B hot-rolled wire rod is mainly used to produce high-strength prestressed steel strands. Due to its high strength and good relaxation properties, the steel strands produced are widely used in important load-bearing structures in fields such as long-span bridges, high-rise buildings, airports, water conservancy and hydropower dams, ports and wharves, and rock slope protection, anchoring, and lifting projects. With the rapid development of my country's economy, its application areas are constantly expanding, and the market development prospects are promising. At the same time, green, safe, and environmentally friendly practices are gradually becoming a common consensus. To achieve environmental protection, energy conservation, and reduced production costs, downstream steel strand processing technology has gradually eliminated environmentally impactful and energy-intensive processes such as pickling and annealing, adopting short-process, direct-feed high-speed wire drawing technology to produce steel strands. With the changes in downstream steel strand production and processing technology and the increasing safety requirements in steel strand application fields, higher demands are being placed on the processing and performance of SWRH82B.

[0003] SWRH82B is a hypereutectoid steel, and its properties make it highly susceptible to the formation of a central network cementite structure during the rolling process. This network cementite structure is a major quality defect in SWRH82B wire rod production. Due to the significant difference in plasticity between the central network cementite structure and the normal structure of the wire rod, the network cementite structure exhibits poor plasticity. During the drawing and twisting process of steel strands, areas with network cementite are prone to becoming crack initiation points, leading to wire breakage. Furthermore, if the core of the wire rod contains a network cementite structure, and the internal quality defects of the produced steel strands are not detected in time before being used in engineering projects, it will pose a serious safety hazard to the load-bearing capacity of the project. Therefore, relevant domestic and international standards have clearly defined requirements for the network cementite structure level of the base material wire rods used in prestressed steel strands.

[0004] Currently, SWRH82B wire rods used in China for steel strand production are all manufactured using high-speed wire rod mills. After high-speed rolling, the rolled strands are coiled and cooled on air-cooled roller conveyors to obtain the required metallographic structure and mechanical properties. According to existing patents and research reports, manufacturers of SWRH82B high-strength wire rods have improved control measures and strengthened management throughout the entire process from steelmaking to rolling, including raw materials, steelmaking and rolling equipment, and process control technology. While their SWRH82B high-strength wire rods can meet user needs, the production process suffers from the following problems: high requirements for equipment precision and capacity; unstable metallographic structure and properties within the same coil; a small amount of 1.5–3.0 grade network cementite structure; and a small number of wire breaks still occur during the wire rod drawing process, which restricts the product's usability.

[0005] Therefore, in view of the above-mentioned technical problems and defects, there is an urgent need to design and develop a rolling controlled cooling method to reduce the network cementite in SWRH82B hot-rolled wire rod. Summary of the Invention

[0006] To overcome the shortcomings and difficulties of the existing technology, the purpose of this invention is to provide a rolling controlled cooling method to reduce the amount of network cementite in SWRH82B hot-rolled wire rod.

[0007] The purpose of this invention is to provide a rolling controlled cooling method for reducing the network cementite in SWRH82B hot-rolled wire rod.

[0008] The objective of this invention is achieved as follows: hot-rolled wire rod network cementitious billet is heated and rolled into a smooth circle in 24 passes; after rolling, it is water-cooled and wire-stretched to obtain loose coils of the required specifications; the loose coils are then transported, air-cooled, coiled, air-cooled on the PF line, trimmed at the ends, and packaged to obtain the final product.

[0009] The method includes the following steps:

[0010] The present invention involves heating and rolling SWRH82B square billets into smooth rounds in 24 passes; water cooling and wire drawing after rolling to obtain loose coils of the required specifications; sequentially transporting the loose coils, air cooling, coiling, air cooling on the PF line, trimming the ends, and packaging to obtain the final product. This further reduces the amount of network cementite in existing prestressed steel strands using SWRH82B hot-rolled wire rods with a nominal diameter of 12.5mm.

[0011] In other words, through the integrated innovation of cooling control processes such as final rolling temperature, post-rolling water cooling, wire drawing speed, wire drawing temperature, roller speed, and fan air volume and speed of SWRH82B, the metallographic structure and mechanical properties of the wire rod in the same ring have been effectively improved, the metallographic structure and mechanical properties of the wire rod in the whole bar are better, the wire breakage phenomenon during wire drawing is avoided, and the user's needs are better met. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the rolling cooling method for reducing the network cementite in SWRH82B hot-rolled wire rod according to the present invention.

[0013] Figure 2 This is a schematic diagram of the metallographic structure of a rolling controlled cooling method for reducing the network cementite in SWRH82B hot-rolled wire rod according to the present invention: 12.5mm S (90%~95%) + P (5%~10%).

[0014] Figure 3 This is a schematic diagram of the metallographic structure of a rolling controlled cooling method for reducing the network cementite in SWRH82B hot-rolled wire rod according to the present invention: 6.5mm S(95%)+P(5%).

[0015] Figure 4 This is a schematic diagram of the metallographic structure of an embodiment three of the rolling controlled cooling method for reducing the network cementite in SWRH82B hot-rolled wire rod of the present invention: 8mm S(95%)+P(5%). Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings, but this is not intended to limit the present invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0017] As attached Figure 1-4 As shown, the present invention provides a rolling controlled cooling method to reduce the network cementite in SWRH82B hot-rolled wire rod.

[0018] The method includes the following steps:

[0019] S1. The SWRH82B square billet is heated and rolled into a 12.5mm bright circle in 24 passes;

[0020] S2. After rolling, water cooling and wire drawing are performed to obtain loose coiled strips of the required specifications;

[0021] S3. Sequentially transport loose coils and air cool, coils are collected, air-cooled on the PF line, trim the beginning and end, and packaged.

[0022] The process of heating and rolling the SWRH82B square billet into a 12.5mm bright circle in 24 passes specifically involves heating a qualified 165mm×165mm cross-section SWRH82B square billet and rolling it into a 12.5mm bright circle in 24 passes.

[0023] The final rolling temperature range for the 24 passes of rolling into 12.5mm bright rounds is controlled between 960℃ and 980℃.

[0024] During the process of post-rolling water cooling and spinning to obtain the required loose coiled wire rod, four nozzles in the water tank are opened, with a water pressure of 0.60MPa~0.65MPa and a flow rate of 32m³ / h. 3 / h~42m 3 / h, control the spinning temperature to 890℃~920℃, and the spinning speed to 26m / s~30m / s.

[0025] During the sequential steps of unrolled transport and air cooling, coiling, air cooling on the PF line, trimming the ends, and packaging, the diameter difference of the unrolled coil is controlled to be 85mm to 96mm.

[0026] The speed of the roller conveyors in sections 1 to 3 increases gradually; the speed of the roller conveyors in sections 4 to 5 decreases gradually; the speed of the roller conveyors in sections 6 to 12 and the last section is the same as that in section 5, controlled at 0.85m / s to 0.86m / s.

[0027] During the sequential steps of unwinding, air cooling, coiling, air cooling on the PF line, trimming the ends, and packaging, the insulation cover is fully open, and fans 1 through 10 are turned on; the air volume is 260,000 m³ / h. 3 / h, the wind speed is controlled at 50m / s~55m / s at the edge and 44m / s~48m / s in the middle, so that the wire rod is rapidly cooled in the range of fans 1 to 6, and the overlap and non-overlap points of the wire rod have a supercooling of 10℃~20℃.

[0028] The sorbite phase transformation was completed in the section between fans 7 and 10. The temperature at the outlet of fan 10 was controlled at 500℃ to 550℃ at the overlapping point and at 480℃ to 530℃ at the non-overlapping point.

[0029] The winding, air cooling on the PF line, trimming of the beginning and end, and packaging are all done by natural air cooling.

[0030] Specifically, in a specific embodiment of the present invention, the present invention provides a rolling controlled cooling method for reducing the amount of network cementite in 12.5mm specification SWRH82B hot-rolled wire rod, the method comprising the following steps:

[0031] A. The qualified 165mm×165mm cross-section SWRH82B square billet is heated and rolled into a 12.5mm bright circle in 24 passes.

[0032] B. After rolling, water cooling and wire drawing yield loose coils of the required specifications.

[0033] C. Loose roll transportation and air cooling, coiling, air cooling on the PF line, trimming of the beginning and end, and packaging are then completed.

[0034] In step A of this invention, the 24 passes of rolling to produce 12.5mm smooth round wire have a final rolling temperature controlled at 960℃~980℃. The purpose is to increase the final rolling deformation temperature to raise the subsequent sorbite phase transformation temperature of the wire rod, and to provide a certain cooling rate when water-cooled to the specified wire drawing temperature, thus providing sufficient driving force for the subsequent sorbite phase deformation nucleation.

[0035] In step B of this invention, the post-rolling water cooling and wire spinning process involves opening four nozzles in the water tank, with a water pressure of 0.60 MPa to 0.65 MPa and a flow rate of 32 m³ / s. 3 / h~42 m 3 The coiling temperature is controlled at 890℃~920℃ and the coiling speed at 26m / s~30m / s per hour. The purpose is to adjust the water pressure and flow rate of the water tank according to the final rolling temperature and speed so that the rolled piece is cooled to the required coiling temperature at a certain cooling rate.

[0036] In step C of this invention, the uncoiled transport involves a reasonable match between the initial roller speed and the coiling speed, controlling the diameter difference of the uncoiled sections to be 85mm-96mm. This aims to prevent excessively dense stacking of the uncoiled sections, which would affect the penetration of air during cooling, leading to insufficient cooling speed and uneven cooling, resulting in the precipitation of network cementite in localized areas. Simultaneously, it prevents excessively high roller speeds from causing the coil to remain above the fan for too short a time, resulting in insufficient sorbite transformation, or even the sorbite transformation occurring after the fan, leading to the precipitation of network cementite. The roller speeds of sections 1 to 3 increase progressively, with each speed increment satisfying ΔV ≥ D / 1000 / (diameter difference / 1000 / initial speed). This ensures that the overlap points of each section of coil are completely staggered, guaranteeing that the cooling speed at the overlap points meets the requirements, preventing the precipitation of network cementite at the overlap points, and improving the overall cooling efficiency. The stability of the wire rod's performance is ensured through the following: The speed of the rollers in sections 4 and 5 is gradually reduced, with each reduction satisfying ΔV ≥ D / 1000 / (diameter difference / 1000 / first section speed). This aims to completely stagger the overlap points of each section of wire rod, while appropriately reducing the cooling rate in the sorbite transformation zone and ensuring the wire rod's residence time above the blower, allowing for sufficient sorbite transformation. The speed of the rollers in sections 6 to 12 and the final section is maintained at the same speed as section 5, controlled at 0.85 m / s to 0.86 m / s. This allows the loose coils to cool naturally under conditions conducive to normal coiling production.

[0037] In step C of this invention, the air-cooled system is operated with the insulation cover fully open and fans #1 to #10 turned on. The airflow is 260,000 m³ / s. 3 The wind speed is 50-55 m / s at the edges and 44-48 m / s in the middle, ensuring rapid cooling of the wire rod between fans 1 and 6. This also maintains a 10-20°C supercooling at both the overlap and non-overlap points. The aim is to ensure appropriate cooling rates at both the overlap and non-overlap points during the sorbitic transformation, preventing secondary cementite from precipitating in the high-temperature zone and preventing carbon from migrating from the near-surface area to the core, thus preventing the formation of central network cementite. It also prevents excessively rapid cooling at non-overlap points, thus preventing the formation of central martensite. The sorbitic transformation is completed between fans 7 and 10. At the outlet of fan 10, the temperature at the overlap point is controlled at 500-550°C, and the temperature at the non-overlap point is controlled at 480-530°C. This is to facilitate a full sorbitic transformation of the wire rod and prevent martensite formation.

[0038] In step C of this invention, the processes of coiling, air cooling on the PF line, trimming the beginning and end, and packaging are all performed using natural air cooling.

[0039] To further reduce the network cementite in existing 12.5mm nominal diameter SWRH82B hot-rolled wire rods used for prestressed steel strands, this invention provides a rolling controlled cooling method to reduce the network cementite in 12.5mm nominal diameter SWRH82B hot-rolled wire rods. Through integrated innovation of controlled cooling processes such as final rolling temperature, post-rolling water cooling, wire drawing speed, wire drawing temperature, roller speed, and fan airflow and velocity, a SWRH82 hot-rolled wire rod with a microstructure of sorbite (90%–95%) + spheroidite (5%–10%), central network cementite <0.5 grade and no central martensite, tensile strength difference within the same coil ≤40MPa, and reduction of area ≥52% is obtained. This effectively improves the metallographic structure and mechanical properties of the wire rod, avoids wire breakage during wire drawing and twisting, better meets user needs, and enhances product competitiveness.

[0040] In other words, this invention appropriately increases the sorbite phase transformation temperature of the subsequent wire rod by increasing the final rolling deformation temperature, and ensures a certain cooling rate when water cooling reaches the specified wire drawing temperature, providing sufficient driving force for the subsequent sorbite phase deformation nuclei; the speed of the first section of the roller table is reasonably matched with the wire drawing speed, and the difference in the unwound diameter is controlled to be 85mm~96mm, which effectively prevents the unwound layers from being too dense, affecting the penetration of air during air cooling, resulting in the wire rod cooling rate being too low and the precipitation of network cementite in localized areas due to uneven cooling. Simultaneously, it prevents excessively high roller speeds, which could lead to insufficient sorbite phase transformation due to short dwell time of the wire rod above the blower, or even sorbite phase transformation occurring after the blower, resulting in the precipitation of network cementite. The roller speeds of sections 1 to 3 increase progressively, with each speed increment satisfying ΔV ≥ D / 1000 / (diameter difference / 1000 / first section speed). This ensures that the overlap points of each section of wire rod are completely staggered, guaranteeing that the cooling rate at the overlap points meets the requirements, preventing the precipitation of network cementite at the overlap points, and improving the stability of the wire rod's overall performance. The roller speeds of sections 4 to 5 decrease progressively, with each decrease satisfying ΔV ≥ D / 1000 / (diameter difference / 1000 / first section speed). The cooling rate of each section of the wire rod is adjusted to ensure that the overlapping points of each section are completely staggered. At the same time, the cooling rate of the sorbitic phase transformation range is appropriately reduced and the residence time of the wire rod above the fan is ensured so that the wire rod can undergo sufficient sorbitic phase transformation. This results in a metallographic structure of sorbite (90%~95%) + spheroidite (5%~10%), central network cementite <0.5 grade and no central martensite. The wire rod has good process mechanical properties, stable mechanical properties of the whole rod, small difference in the same coil, tensile strength difference in the same coil ≤40MPa, and reduction of area ≥52%. The drawing and twisting deep processing performance is improved, and the wire breakage phenomenon during the drawing and twisting process of prestressed steel strand is effectively avoided.

[0041] The process of this invention has the characteristics of strong process applicability and controllability. It requires fewer units of air-cooled fans in the high-speed wire rod production line. The produced wire rod has excellent deep processing performance, effectively avoids wire breakage during the drawing and twisting process of prestressed steel strands, and significantly improves the market competitiveness of the product.

[0042] Example 1

[0043] The qualified 165mm×165mm cross-section SWRH82B square billet was heated and rolled in 24 passes into a 12.5mm diameter smooth round SWRH82B, with the final rolling temperature controlled at 960℃. Four nozzles in the water tank were opened, with a water pressure of 0.65MPa and a flow rate of 42 m³ / s. 3 The spinning temperature is 890℃, the spinning speed is 30m / s, and the speed of the first section roller conveyor is adjusted to 0.76m / s to ensure a loose coil diameter difference of 85mm. The speeds of sections 1 to 3 increase progressively, with each speed increment satisfying ΔV≥D / 1000 / (diameter difference / 1000 / first section speed). The speed increment is set to 0.12m / s, i.e., the speed of section 1 is 0.88m / s, section 2 is 1.00m / s, and section 3 is 1.12m / s. The speeds of sections 4 to 5 decrease progressively, with each decrease set to 0.12m / s, i.e., the speed of section 4 is 1.00m / s and section 5 is 0.88m / s. The speeds of sections 6 to 12 and the final section are kept at the same speed as section 5, 0.88m / s. At the same time, the insulation covers on the loose-roll transport line are fully opened, and fans #1 to #10 are turned on, with an air volume of 260,000 m³ / h. 3 / h, wind speed: 55m / s at the edges and 48m / s in the middle of fans 1# to 3#; 52m / s at the edges and 46m / s in the middle of fans 4# to 6#; 50m / s at the edges and 44m / s in the middle of fans 7# to 10#. Using a handheld thermometer, the temperature at the non-overlapping point of the wire rod was 596℃ in the upper middle of fan 6#, at which point the sorbite phase transformation began; at the overlapping point, the temperature cooled to 612℃ at the outlet of fan 6#, at which point the sorbite phase transformation began again. The temperature at the overlapping point at the outlet of fan 10# was 548℃, and the temperature at the non-overlapping point was 526℃.

[0044] Samples from the same coil of the obtained wire rod were tested for metallographic structure and mechanical properties according to YB / T 169, YB / T4411, YB / T4412, and GB / T 228.1. The metallographic structure was S (90%~95%) + P (5%~10%), without central martensite or network cementite. The average tensile strength was 1190MPa, with a difference of 40MPa between coils. The average reduction of area was 52%, with a difference of 3% between coils. No wire breakage was observed during user use, meeting the user's requirements.

[0045] Example 2

[0046] The qualified 165mm×165mm cross-section SWRH82B square billet was heated and rolled in 24 passes into a 12.5mm diameter smooth round SWRH82B, with the final rolling temperature controlled at 968℃. Four nozzles in the water tank were opened, with a water pressure of 0.62MPa and a flow rate of 36 m³ / h. 3 The spinning temperature is 902℃, and the spinning speed is 28m / s. The speed of the first section roller conveyor is adjusted to 0.75m / s to ensure a loose coil diameter difference of 90mm. The speeds of sections 1 to 3 increase progressively, with each speed increment satisfying ΔV≥D / 1000 / (diameter difference / 1000 / first section speed). The speed increment is set to 0.11m / s, i.e., the speed of section 1 is 0.86m / s, section 2 is 0.97m / s, and section 3 is 1.08m / s. The speeds of sections 4 to 5 decrease progressively, with each decrease set to 0.11m / s, i.e., the speed of section 4 is 0.97m / s, and section 5 is 0.86m / s. The speeds of sections 6 to 12 and the final section are kept at the same speed as section 5, 0.86m / s. At the same time, the insulation covers on the loose-roll transport line are fully opened, and fans #1 to #10 are turned on, with an air volume of 260,000 m³ / h. 3 / h, wind speed: 55m / s at the edges and 48m / s in the middle of fans 1# to 3#; 52m / s at the edges and 46m / s in the middle of fans 4# to 6#; 50m / s at the edges and 44m / s in the middle of fans 7# to 10#. Using a handheld thermometer, the temperature at the non-overlapping point of the wire rod was 588℃ in the upper middle of fan 6#, initiating the sorbitic phase transformation; at the overlapping point, the temperature at the outlet of fan 6# was 602℃, also initiating the sorbitic phase transformation. The temperature at the overlapping point at the outlet of fan 10# was 527℃, and the temperature at the non-overlapping point was 498℃.

[0047] Samples from the same coil of the obtained wire rod were tested for metallographic structure and mechanical properties according to YB / T 169, YB / T4411, YB / T4412, and GB / T 228.1. The metallographic structure was S (95%) + P (5%), without central martensite or network cementite. The average tensile strength was 1190 MPa, with a difference of 30 MPa between coils. The average reduction of area was 52%, with a difference of 3% between coils. No wire breakage was observed during user use, meeting the user's requirements.

[0048] Example 3

[0049] The qualified 165mm×165mm cross-section SWRH82B square billet was heated and rolled in 24 passes into a 12.5mm diameter smooth round SWRH82B, with the final rolling temperature controlled at 980℃. The water tank had four nozzles open, the water pressure at 0.60MPa, and the flow rate at 32 m³ / s. 3The spinning temperature is 920℃, the spinning speed is 26m / s, and the speed of the first section roller is adjusted to 0.75m / s to ensure a loose coil diameter difference of 96mm. The speeds of sections 1 to 3 increase progressively, with each speed increment satisfying ΔV≥D / 1000 / (diameter difference / 1000 / first section speed). The speed increment is set to 0.10m / s, i.e., the speed of section 1 is 0.85m / s, section 2 is 0.95m / s, and section 3 is 1.05m / s. The speeds of sections 4 to 5 decrease progressively, with each decrease set to 0.10m / s, i.e., the speed of section 4 is 0.95m / s, and section 5 is 0.85m / s. The speeds of sections 6 to 12 and the final section are kept at the same speed as section 5, 0.85m / s. At the same time, the insulation covers on the loose-roll transport line are fully opened, and fans #1 to #10 are turned on, with an air volume of 260,000 m³ / h. 3 / h, wind speed: 55m / s at the edges of fans 1# to 3#, 48m / s in the middle; 52m / s at the edges of fans 4# to 6#, 46m / s in the middle; 50m / s at the edges of fans 7# to 10#, 44m / s in the middle. Using a handheld thermometer, the temperature at the non-overlapping point of the wire rod was 580℃ in the upper middle of fan 6#, initiating the sorbitic phase transformation; at the overlapping point, the temperature at the outlet of fan 6# was 591℃, also initiating the sorbitic phase transformation. At the outlet of fan 10#, the temperature at the overlapping point was 502℃, and the temperature at the non-overlapping point was 487℃.

[0050] Samples from the same coil of the obtained wire rod were tested for metallographic structure and mechanical properties according to YB / T 169, YB / T4411, YB / T4412, and GB / T 228.1. The metallographic structure was S (95%) + P (5%), without central martensite or network cementite. The average tensile strength was 1180 MPa, with a difference of 30 MPa between coils. The average reduction of area was 54%, with a difference of 3% between coils. No wire breakage was observed during user use, meeting the user's requirements.

Claims

1. A rolling controlled cooling method for reducing the network cementite in SWRH82B hot-rolled wire rod, characterized in that, The method includes the following steps: S1. The qualified 165mm×165mm cross-section SWRH82B square billet is heated and rolled into a 12.5mm bright circle in 24 passes, with the final rolling temperature controlled within the range of 960℃~980℃. S2. After rolling, water cooling and spinning are performed to obtain loose coils of the required specifications. Specifically, four nozzles in the water tank are opened, the water pressure is 0.60MPa~0.65MPa, and the flow rate is 32m³ / h. 3 / h~42m 3 / h, control the spinning temperature at 890℃~920℃, and the spinning speed at 26m / s~30m / s; S3. Sequentially transport loose coils, air-cool them, coil them together, air-cool them on the PF line, trim the beginning and end, and package them. Specifically: The speed of the first section of the loose coil conveyor is reasonably matched with the spinning speed to control the loose coil diameter difference to be 85mm~96mm; the speed of the first to third sections of the conveyor increases gradually, and the speed increment of each section satisfies △V≥D / 1000 / (diameter difference / 1000 / first section speed); the speed of the fourth to fifth sections of the conveyor decreases gradually, and the speed reduction of each section satisfies △V≥D / 1000 / (diameter difference / 1000 / first section speed); the speed of the sixth to twelfth sections and the last section of the conveyor maintains the same speed as the fifth section, controlled at 0.85m / s~0.86m / s; where D in △V is the diameter of the smooth circle, 12.5mm; During air cooling, the insulation covers on the unrolled coil conveyor line are fully open, and fans 1 through 10 are turned on, with an air volume of 260,000 m³ / h. 3 / h, the edge wind speed is controlled at 50m / s~55m / s and the middle wind speed is controlled at 44m / s~48m / s, so that the wire rod is rapidly cooled in the section between fans 1 to 6, and the supercooling at the overlapping and non-overlapping points of the wire rod is 10℃~20℃; the sorbite phase transformation is completed in the section between fans 7 to 10, and the temperature at the overlapping point of the outlet of fan 10 is controlled at 500℃~550℃, and the temperature at the non-overlapping point is controlled at 480℃~530℃.

2. The rolling controlled cooling method according to claim 1, characterized in that, The winding, air cooling on the PF line, trimming of the beginning and end, and packaging are all done by natural air cooling.

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