Low-cost rolling method for high-speed coiled spiral wire

Abstract

The invention belongs to the technical field of austenite control of steel rolling wires, and particularly relates to a low-cost rolling method for a high-speed coiled wire, which improves the quality of a wire product, reduces the production cost, is a novel high-speed wire rolling method, can greatly improve the quality of the high-speed wire in China, has remarkable economic benefits and is suitable for industrial production. The method has great market popularization and application value on an existing production line, the strength of a finished wire is improved by 10-20 MPa, alloy elements are saved, and the production cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of controlled austenite of rolled steel wires, and in particular relates to a low-cost rolling method for high-speed coiled wires. Background Art

[0002] The coil is a hot-rolled threaded steel coil produced by a high-speed wire mill. The main specifications are: Φ6mm, Φ8mm, Φ10mm, Φ12mm. According to GB1499.2-2018, its chemical composition C% is not more than 0.25%, Mn% is not more than 1.6%, and carbon equivalent Ceq is not more than 0.54. After spinning into a loop, Stelmor air-cooling wire is generally used for cooling. This process method has achieved remarkable results in controlling the microstructure and properties of high-speed wires. It is a relatively complete high-speed wire air-cooling process.

[0003] When producing ￠8mm and ￠10mm coils, in order to ensure the stability of the production process and reduce the failure of water penetration after rolling, the head does not penetrate water for about 15-20 turns. In order to ensure that the head does not penetrate water to meet the standard requirements, the Mn content in the steel is controlled at about 1.2%, which increases production costs and reduces corporate profits. There is an urgent need to reduce production costs and ensure product quality. Summary of the invention

[0004] In order to solve the above-mentioned high production cost problem, the present invention provides a low-cost rolling method for high-speed coil wire and significantly improves the wire quality. The specific technical solution is as follows: A method for rolling high-speed coiled wire at low cost, comprising the following steps: (1) Two dephosphorization devices were installed on the heat preservation rollers at the exit of the heating furnace, and two annular cooling devices were added before the rough rolling mill No. 1. The surface temperature of the steel billet was reduced to 900°C by the added dephosphorization devices and annular cooling devices, and the temperature difference between the center and the surface reached 100°C, thereby increasing the deformation of the center area of ​​the rolled piece. According to the conventional controlled rolling theory, the microstructure and mechanical properties of the center area of ​​the steel were improved; (2) The temperature before pre-watering reaches about 1020°C. After pre-watering, the temperature of the rolled piece entering the finishing mill is guaranteed to be between 780-830°C, avoiding excessive final rolling temperature and ensuring that the steel has a finer grain size; (3) The air-cooled line adopts aerosol cooling to control the cooling process of the coil above the dense roller between the spinning machine and the No. 1 fan and the No. 1 and No. 2 fan ducts, in order to achieve two cooling effects: First, the cooling intensity at the wire overlap point is enhanced to make the temperature of the entire coil uniform and ensure a smaller performance difference in the same coil (the performance difference in the same coil can be reduced by 15-20 MPa). Second, the cooling rate of the wire is increased (reaching 15-30℃ / s), preventing the grain from growing, thereby achieving grain refinement and improving the mechanical properties of the finished product (15-20MPa).

[0005] After the technical improvement, the cooling speed of the coil after spinning is increased, the growth of austenite and ferrite grains after spinning is inhibited, the ferrite grains are refined, the size of pearlite groups is reduced, the Widmanstatten structure is eliminated, and the product strength is improved. The Mn content in the steel can be controlled to be reduced to about 0.9%, which reduces production costs and ensures the stability of the process.

[0006] Beneficial effects of the present invention: 1. Compared with the prior art, the present invention improves the quality of wire products and reduces production costs. It is a new high-speed wire rolling method, which can greatly improve the quality of my country's high-speed wires, has significant economic benefits, and has great market promotion and application value on existing production lines.

[0007] 2. This process can increase the cooling speed of the wire after spinning, flexibly control the phase change process of the wire, and increase the strength of the finished wire by 10 to 20 MPa when the wire composition is the same, saving alloy elements and reducing production costs.

[0008] 3. This process method reduces the temperature difference between the center and the surface, and improves the organization and mechanical properties of the central area of ​​the steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 The figure shows a comparison of online temperature measurement of each fan in a specific example of the present invention and a normal process; Figure 2 Shown is a metallographic pearlite content diagram of a specific example of the present invention; Figure 3 Shown is a metallographic grain size diagram of a specific example of the present invention; Figure 4 Shown is the pearlite content of the metallographic sample of the comparison sample; Figure 5 Shown is the metallographic grain size diagram of the comparison sample. DETAILED DESCRIPTION

[0010] The technical solution of the present invention is further defined below in conjunction with specific implementation methods, but the scope of protection required is not limited to the description.

[0011] Example 1 A method for rolling high-speed coiled wire at low cost, comprising the following steps: (1) Two dephosphorization devices are installed on the heat preservation rollers of the heating furnace, and two annular cooling devices are added before the rough rolling mill No. 1. The surface temperature of the steel billet is reduced to 900°C by the added dephosphorization devices and annular cooling devices, and the temperature difference between the center and the surface reaches 100°C, thereby increasing the deformation of the central area of ​​the rolled piece. According to the conventional controlled rolling theory, the microstructure and mechanical properties of the central area of ​​the steel are improved; the dephosphorization device is a high-pressure water dephosphorization device, and the annular cooling device is an annular water spray cooling device; (2) The temperature before pre-watering reaches about 1020°C. After pre-watering, the temperature of the rolled piece entering the finishing mill is guaranteed to be between 780-830°C, avoiding excessive final rolling temperature and ensuring that the steel has a finer grain size; (3) The air-cooled line adopts aerosol cooling to control the cooling process of the coil above the dense roller between the spinning machine and the No. 1 fan and the No. 1 and No. 2 fan ducts, in order to achieve two cooling effects: First, the cooling intensity at the wire overlap point is enhanced to make the temperature of the entire coil uniform, ensuring a small performance difference in the same coil, and the performance difference in the same coil is reduced by 15-20 MPa. Second, the cooling rate of the wire is increased (reaching 15-30℃ / s), preventing the growth of grains, thereby achieving grain refinement and improving the mechanical properties of the finished product (15-20MPa).

[0012] When the high-speed coiled wire low-cost rolling method of the present invention is actually operated: 1. The water pressure of the heating furnace dephosphorization device is 15MPa, and the water pressure of the annular cooling device is 5MPa. All valves connecting the cooling water pipes are opened.

[0013] 2. After pre-finishing rolling, all three water tanks are opened.

[0014] 3. All 9 groups (5 horizontal groups and 4 vertical groups) of cooling devices above the 1# fan are turned on when spinning.

[0015] 4. Turn on the 1# and 2# fans of the Stelmore air cooling line.

[0016] 5. Open all the valves connecting the 1# and 2# fan cooling devices.

[0017] 6. The rolled wire is spit out into a circle by the spinning machine and then scattered through the spinning to the air-water mixed medium above the 1# fan, and the air-water mixed medium of the 1# and 2# fans to reduce the temperature of the finished product to 680-700℃.

[0018] 7. After passing through the 3# air-cooling roller, the wire enters the phase change temperature and is continuously transported by the remaining air-cooling rollers until the air cooling is completed.

[0019] The actual production performance results of this embodiment are as follows: See Figure 1-5It can be seen that the fan cooling effect of this embodiment is significant. The grain size of the spiral shell produced by this process is refined and the pearlite content is high, resulting in an improvement in the performance of the spiral shell to 15-20MPa.

Claims

1. A method for rolling high-speed coiled wire at low cost, characterized in that: The steps include: (1) Install two dephosphorization devices on the heat preservation rollers at the outlet of the heating furnace and add two ring cooling devices in front of the rough rolling mill No. 1; (2) Control the temperature of the rolled product entering the finishing mill; (3) The air cooling line is set above the dense roller between the spinning machine and the No. 1 fan, and the No. 1 and No. 2 fan ducts use mist cooling to control the cooling of the coil.

2. A low-cost rolling method for high-speed coiled wire according to claim 1, characterized in that: The dephosphorization device and the annular cooling device reduce the surface temperature of the steel billet to 900°C, and the temperature difference between the center and the surface reaches 100°C.

3. A low-cost rolling method for high-speed coiled wire according to claim 1, characterized in that: The temperature of the rolled piece entering the finishing mill is 780-830°C.

4. A low-cost rolling method for high-speed coiled wire according to claim 1, characterized in that: The method for controlling the temperature of the rolled piece entering the finishing mill is to pre-run the rolled piece through water.

5. A low-cost rolling method for high-speed coiled wire according to claim 1, characterized in that: The coil same-turn performance difference is reduced by 15-20 MPa.

6. A method for rolling high-speed coiled wire at low cost according to claim 1, characterized in that: The cooling rate of the wire is 15-30°C / s.

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