Rolling method for reducing carbon level of high-carbon steel wire rod net
By controlling the heating, rolling and cooling processes of high-carbon steel coils, the problem of the strips easily forming harmful tissue during the drawing processing is solved, and the reduction of the mesh carbon level and the improvement of the drawing performance are achieved.
Patent Information
- Application Number
- CN202510077636.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-17
- Publication Date
- 2025-05-06
AI Technical Summary
High-carbon steel strips are prone to form harmful tissues during the drawing processing, such as martensite, bainite, mesh carbon cementite, etc., resulting in central cracks and drawing fractures.
By controlling the heating temperature and time of the heating furnace, the diffusion of segregated elements in the center of the casting billet is promoted; the final rolling temperature and the spinning temperature are controlled to promote sufficient deformation of the center of the strip and grain recrystallization; the segmented cooling process is adopted to quickly cool and control the cooling speed, delay the pearlite phase transformation and refine the pearlite sheet layer.
It effectively reduces the mesh carbon level of high-carbon steel strips, ensures that their internal structure is uniform to soxunite, improves the pulling performance, and avoids central cracks and fractures.
Smart Images
Figure CN119932285A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of high carbon steel wire production, and in particular relates to a rolling method for reducing the carbon grade of a high carbon steel wire rod mesh. Background Art
[0002] High carbon steel wire rod is mainly used to produce various specifications of steel wire, wire rope, prestressed steel wire, steel strand, etc. Its main processing feature is that the hot rolled wire rod is directly drawn after surface treatment to remove the oxide scale, until it is drawn to the required finished product or the specification that needs heat treatment. Therefore, this type of wire rod has high requirements for abnormal structure in the center. Due to the existence of central segregation, high carbon steel, especially hypereutectoid steel, has a high content of alloy elements in the center, which is easy to form harmful structures such as martensite, bainite, and carbon cementite that affect drawing during phase transformation. These harmful structures have poor plasticity and cannot coordinate deformation with the surrounding troostite structure during the drawing process, thus forming a central crack, which can lead to drawing fracture in severe cases. Summary of the invention
[0003] The present invention aims to provide a rolling method for reducing the carbon level of a high carbon steel wire rod mesh, which can control the carbon level of the high carbon steel wire rod mesh to below level 2, and has a uniform sorbite structure and excellent drawing performance.
[0004] To achieve the above purpose, the technical solution of the present invention is as follows: A rolling method for reducing the carbon grade of a high-carbon steel wire rod mesh comprises the steps of heating a steel billet, controlling rolling and controlling cooling.
[0005] Preferably, the steel billet heating process of the present invention comprises: heating the steel billet in a heating furnace, with an absorptive temperature of 1200-1250° C. and a total heating time of 70-150 min.
[0006] Preferably, in the controlled rolling process of the present invention, the final rolling temperature is 800-860°C, and the spinning temperature is 910-960°C.
[0007] Preferably, the controlled cooling step of the present invention is as follows: after spinning, the wire rod is cooled in sections: ① After spinning, use appropriate roller speed and fan opening, and add fan water mist device to quickly cool the wire rod to 590-610℃, with a cooling rate of 10-20℃ / s; ② The wire rod turns red, and the red-turning temperature is ≤650℃; ③ The wire rod is cooled from the red-return temperature to 430-450℃, and the cooling rate is controlled at 3-10℃ / s; ④ During the cooling process of the wire rod below 430-450℃, the cooling rate is controlled to be >3℃ / s.
[0008] Furthermore, the chemical composition of the high carbon steel wire rod of the present invention is: C 0.77-0.92%, Si 0.10-0.45%, Mn 0.30-0.90%, P≤0.025%, S≤0.025%.
[0009] Furthermore, the specification of the high carbon steel wire rod of the present invention is Ф5.5-16mm.
[0010] The inventive principle and beneficial technical effects of the technical solution of the present invention are: By controlling the heating temperature and heating time of the heating furnace, the diffusion of the center segregation elements of the ingot is promoted and the center segregation is reduced; the final rolling temperature is controlled at 800-860℃, and the center position of the wire rod is fully deformed at a lower rolling temperature to reduce the center segregation; the wire drawing temperature is 910-960℃. With a higher wire drawing temperature, the wire rod grains are fully recrystallized and recovered, the austenite grains are stable and of appropriate size, and the supercooling required for the pearlite phase transformation is increased. After wire drawing, the wire rod is quickly cooled to 590℃-610℃, with a cooling rate of 10-20℃ / s, so that the wire rod quickly passes through the hypereutectoid steel mesh carbon precipitation temperature range of 800-860℃, reducing the mesh carbon precipitation time, delaying the pearlite phase transformation, and refining the pearlite lamellae. The wire rod re-red temperature is controlled to be ≤650℃, so that the pearlite phase transformation is completed in a lower temperature range to avoid pearlite coarsening due to excessively high re-red temperature. The wire rod is cooled from the red-back temperature to 430-450℃ at a relatively fast cooling rate of 3-10℃ / s, which can make the residual austenite in the wire rod complete the pearlite transformation, and avoid the decomposition of the FeO phase in the oxide scale due to too slow cooling rate, so as to obtain the oxide scale that is easy to remove mechanically. The wire rod is cooled below 430-450℃, and the cooling rate is controlled to be greater than 3℃ / s, so that the temperature of the wire rod is reduced and the risk of scratches on the wire rod is reduced. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Figure 1 This is the metallographic structure of the central cross section of the high carbon steel wire rod in Example 1.
[0012] Figure 2 This is the metallographic structure of the surface cross section of the high carbon steel wire rod in Example 3. DETAILED DESCRIPTION
[0013] The technical solution of the present invention is further described in detail below in conjunction with embodiments. Example 1
[0014] The chemical composition of the wire rod of this embodiment is shown in Table 1, and the specification is Ф10mm; its rolling process is: heating of steel billet → controlled rolling → controlled cooling, and the specific process control is as follows: (1) Billet heating: The billet is heated in a heating furnace with an average heating temperature of 1200°C and a total heating time of 70 min.
[0015] (2) Controlled rolling: final rolling temperature 810°C, spinning temperature 923°C.
[0016] (3) Controlled cooling: After spinning, the wire rod is cooled in sections as follows: ①After spinning, the wire rod is quickly cooled to 605℃, with a cooling rate of 13.4℃ / s; ②The wire rod red-return temperature is 642℃; ③ The wire rod is cooled from 642℃ to 450℃, with a cooling rate of 7℃ / s; ④ The cooling process of the wire rod below 450℃, the cooling rate is 3.8℃ / s.
[0017] The internal structure of the finished wire rod of this embodiment is uniform troostite. Figure 1 As shown, the center mesh is carbon grade 1. Example 2
[0018] The chemical composition of the wire rod of this embodiment is shown in Table 1, and the specification is Ф12.5mm; its rolling process is: billet heating → controlled rolling → controlled cooling; the specific process control is as follows: (1) Billet heating: The billet is heated in a heating furnace with an average heating temperature of 1240°C and a total heating time of 120 min.
[0019] (2) Control the rolling process, the final rolling temperature is 821℃, and the wire drawing temperature is 923℃.
[0020] (3) Control the cooling process. After spinning, the wire rod is cooled in sections as follows: ①After spinning, the wire rod is quickly cooled to 610℃, with a cooling rate of 12.8℃ / s; ②The wire rod red-return temperature is 645℃; ③ The wire rod cools from 645℃ to 445℃, with a cooling rate of 5.6℃ / s; ④ The cooling process of the wire rod below 445℃, the cooling rate is 4.2℃ / s.
[0021] The internal structure of the finished wire rod in this embodiment is uniform troostite, and the center network carbon is level 1. Example 3
[0022] The chemical composition of the wire rod of this embodiment is shown in Table 1, and the specification is Ф16mm; its rolling process is: billet heating → controlled rolling → controlled cooling; the specific process control is as follows: (1) Billet heating: The billet is heated in a heating furnace with an average heating temperature of 1250°C and a total heating time of 150 min.
[0023] (3) Controlled rolling: final rolling temperature 860°C, spinning temperature 900°C.
[0024] (3) Controlled cooling: After spinning, the wire rod is cooled in sections as follows: ①After spinning, the wire rod is quickly cooled to 607℃, with a cooling rate of 10℃ / s; ②The wire rod red-return temperature is 650℃; ③ The wire rod is cooled from 650℃ to 430℃, with a cooling rate of 3℃ / s; ④ The cooling process of the wire rod below 430℃, the cooling rate is 3.3℃ / s.
[0025] The internal structure of the finished wire rod of this embodiment is uniform troostite. Figure 2 As shown, the center mesh is carbon grade 2. Example 4
[0026] The chemical composition of the wire rod of this embodiment is shown in Table 1, and the specification is Ф5.5mm; its rolling process is: billet heating → controlled rolling → controlled cooling; the specific process control is as follows: (1) Billet heating: The billet is heated in a heating furnace with an average heating temperature of 1208°C and a total heating time of 138 min.
[0027] (2) Controlled rolling: final rolling temperature 842°C, spinning temperature 960°C.
[0028] (3) Controlled cooling: After spinning, cooling in sections: ①After spinning, the wire rod is quickly cooled to 595℃, with a cooling rate of 18℃ / s; ②The wire rod red-return temperature is 632℃; ③ The wire rod cools from 632℃ to 435℃, with a cooling rate of 8.2℃ / s; ④ The cooling process of the wire rod below 435℃, the cooling rate is 4.8℃ / s.
[0029] The internal structure of the finished wire rod in this embodiment is uniform troostite, and the center network carbon is level 1. Example 5
[0030] The chemical composition of the wire rod of this embodiment is shown in Table 1, and the specification is 6.5 mm in diameter. The rolling process is as follows: heating the steel billet → controlled rolling → controlled cooling. The specific process control is as follows: (1) Billet heating: The billet is heated in a heating furnace with an average heating temperature of 1223°C and a total heating time of 118 min.
[0031] (2) Controlled rolling: final rolling temperature 800°C, spinning temperature 941°C.
[0032] (3) Controlled cooling: After spinning, cooling in sections: ①After spinning, the wire rod is quickly cooled to 590℃, with a cooling rate of 20℃ / s; ②The wire rod red-return temperature is 635℃; ③ Wire rod from 635℃ to 442℃, cooling rate 10℃ / s; ④ The cooling process of the wire rod below 442℃, the cooling rate is 3℃ / s.
[0033] The internal structure of the finished wire rod in this embodiment is uniform troostite, and the center network carbon is level 1. Example 6
[0034] The chemical composition of the wire rod of this embodiment is shown in Table 1, and the specification is 7 mm. The rolling process is as follows: heating the steel billet → controlled rolling → controlled cooling. The specific process control is as follows: (1) Billet heating: The billet is heated in a heating furnace with an average heating temperature of 1200°C and a total heating time of 90 min.
[0035] (2) Controlled rolling: final rolling temperature 800°C, spinning temperature 900°C.
[0036] (3) Controlled cooling: After spinning, cooling in sections: ①After spinning, the wire rod is quickly cooled to 600℃, with a cooling rate of 15.7℃ / s; ②The wire rod red-return temperature is 645℃; ③ The wire rod cools from 645℃ to 438℃, with a cooling rate of 3.8℃ / s; ④ The cooling process of the wire rod below 438℃, the cooling rate is 4.2℃ / s.
[0037] The internal structure of the finished wire rod in this embodiment is uniform troostite, and the center network carbon is level 1.
[0038] Table 1 Chemical composition of wire rods of various embodiments and comparative examples (%) .
Claims
1. A rolling method for reducing the carbon grade of a high carbon steel wire rod mesh, characterized in that: The process includes heating the steel billet, controlled rolling and controlled cooling. The controlled cooling process includes cooling the wire rod in sections after spinning, as follows: ①After spinning, the wire rod is quickly cooled to 590-610℃, with a cooling rate of 10-20℃ / s; ② The wire rod turns red, and the red-turning temperature is controlled to be ≤650℃; ③ The wire rod is cooled from the red-return temperature to 430-450℃, and the cooling rate is controlled at 3-10℃ / s; ④ During the cooling process of the wire rod below 430-450℃, the cooling rate is controlled to be >3℃ / s.
2. A rolling method for reducing the carbon grade of high carbon steel wire rod mesh according to claim 1, characterized in that: The steel billet heating process: the steel billet is heated in a heating furnace, the soaking temperature is 1200-1250° C., and the total heating time is 70-150 minutes.
3. A rolling method for reducing the carbon grade of high carbon steel wire rod mesh according to claim 1, characterized in that: The controlled rolling process includes: a final rolling temperature of 800-860°C and a spinning temperature of 910-960°C.
4. The rolling method for reducing the carbon grade of high carbon steel wire rod mesh according to claim 1, characterized in that: The chemical composition of the high carbon steel wire rod is: C 0.77-0.92%, Si 0.10-0.45%, Mn 0.30-0.90%, P≤0.025%, S≤0.025%.
5. The rolling method for reducing the carbon grade of high carbon steel wire rod mesh according to claim 1, characterized in that: The specification of the high carbon steel wire rod is Ф5.5-16mm.
6. A rolling method for reducing the carbon grade of high carbon steel wire rod mesh according to claim 1, characterized in that: The method can control the carbon grade of the high carbon steel wire rod mesh to below level 2, and the wire rod has a uniform troostite structure.