Wire rod for high-speed wire rod production

Abstract

The present invention provides a wire rod for high-speed wire rod production, and the wire rod for high-speed wire rod production includes: controlling the chemical composition of hot-rolled ribbed steel bars: without adding Nb, V, Ti microalloys, and controlling C: 0.21% - 0.25%, Si: 0.40% - 0.70%, Mn: 0.80% - 1.10%, P≤0.045%, S≤0.045% by weight percentage, and the rest is Fe; the production method includes: rough rolling, medium rolling, pre-finishing rolling, water tank and recovery section after pre-finishing rolling, finishing rolling, water tank and recovery section after finishing rolling, reducing diameter, wire laying, air-cooling roller table cooling, coiling, trimming, and bundling.

Description

Technical Field

[0001] The present invention relates to the field of steel rolling, and particularly to a wire rod for high-speed wire rod production. Background Art

[0002] Wire rods for high-speed wire rod production are widely used in the production of hot-rolled ribbed steel bars due to their high production speed and high output. The national standard for hot-rolled ribbed steel bars stipulates that the metallographic structure should mainly be ferrite plus pearlite, and tempered martensite structure should not appear on the base circle.

[0003] Currently, most steel mills improve the strength of steel bars by adding microalloys such as Nb, V, Ti, etc. to the steel and using methods such as solid solution strengthening, fine grain strengthening, and precipitation strengthening. However, adding microalloys such as Nb, V, Ti, etc. will significantly increase the alloy cost and reduce the enterprise profit.

[0004] In summary, the following problems exist in the prior art: how to produce wire rods for high-speed wire rod production that meet the standards of hot-rolled ribbed steel bars without adding microalloys such as Nb, V, Ti, etc. and without water cooling after rolling. Summary of the Invention

[0005] The present invention provides a wire rod for high-speed wire rod production (especially a hot-rolled ribbed steel bar wire rod for high-speed wire rod production) to produce qualified hot-rolled ribbed steel bars without adding microalloys such as Nb, V, Ti, etc. and without water cooling after rolling.

[0006] To this end, the present invention proposes a wire rod for high-speed wire rod production. The composition of the wire rod for high-speed wire rod production is by weight percentage: C: 0.21% - 0.25%, Si: 0.40% - 0.70%, Mn: 0.80% - 1.10%, P ≤ 0.045%, S ≤ 0.045%, and the rest is Fe;

[0007] The specifications of the hot-rolled ribbed steel bars are φ6 - φ12mm;

[0008] The production method adopts single-line rolling. The finished product specification is φ6mm, and the rolling speed is 105m / s; the finished product specification is φ8mm, and the rolling speed is 90m / s; the finished product specification is φ10mm, and the rolling speed is 64m / s; the finished product specification is φ12mm, and the rolling speed is 40m / s.

[0009] The production method includes: blast furnace hot metal smelting, hot metal desulfurization pretreatment, converter steelmaking, bloom continuous casting, heating furnace heating, rough rolling, intermediate rolling, pre-finishing rolling, water tank cooling after pre-finishing rolling, finishing rolling, water tank cooling after finishing rolling, reducing sizing, wire laying, air-cooling roller table cooling, coiling, trimming, and bundling; the water tank after finishing rolling controls the temperature of the rolling process to prevent the temperature from rising too high during the rolling process and the grain growth, and there is no water cooling after the reducing mill.

[0010] Among them, the starting rolling temperature is 930 - 980 °C, the temperature entering the finishing mill is 900 - 930 °C, the temperature entering the reducing mill is controlled at 840 - 880 °C, and the laying head temperature is 880 - 920 °C (the temperature rise of the steel bar after rolling through the reducing mill is about 40 °C, and there is no water cooling after the reducing mill), and all the heat preservation covers are opened.

[0011] Further, after the hot metal is blown in the BOF, the steel is tapped with a slide gate slag stopper, then alloy and deoxidizer are added to make the C content 0.21% - 0.25%, the Si content 0.40% - 0.70%, the Mn content 0.80% - 1.10%, the P and S contents ≤ 0.045%, and then it is sent to the argon station for argon blowing and cast by the whole-process protection casting process.

[0012] Further, the temperature in the heating section is controlled at 1040 - 1100 °C, the soaking section is controlled at 1030 - 1080 °C, the heating time of the billet is 80 - 120 minutes, the starting rolling temperature is 930 - 980 °C, the temperature entering the finishing mill is 900 - 930 °C, the temperature entering the reducing mill is 840 - 880 °C, and the laying head temperature is 880 - 920 °C (the temperature rise of the steel bar after rolling through the reducing mill is about 40 °C).

[0013] Further, for the φ6mm wire rod, the 1 - 2# fans are turned on with a 100% air volume.

[0014] Further, for the φ8mm wire rod, the 1 - 4# fans are turned on with a 100% air volume.

[0015] Further, for the φ10mm wire rod, the 1 - 6# fans are turned on with a 100% air volume.

[0016] Further, for the φ12mm wire rod, the 1 - 7# fans are turned on with a 100% air volume.

[0017] Further, the chemical composition of the hot-rolled ribbed steel bar is: C: 0.22%%, Si: 0.48%, Mn: 0.88%, P: 0.027%, S: 0.018%, and the rest is Fe.

[0018] Further, the starting rolling temperature is controlled at 956 °C, the temperature entering the finishing mill is 912 °C, the temperature entering the reducing mill is 860 °C, the laying head temperature is 894 °C, and the temperature after air cooling is 709 °C.

[0019] Further, the starting rolling temperature is controlled at 967 °C, the temperature entering the finishing mill is 912 °C, the temperature entering the reducing mill is 849 °C, the laying head temperature is 882 °C, and the temperature after air cooling is 579 °C.

[0020] Further, C: 0.23%%, Si: 0.47%, Mn: 0.91%, P: 0.034%, S: 0.032%, and the rest is Fe.

[0021] Furthermore, the wire rod produced by the high-speed wire rod production of the present invention has a metallographic structure as follows: macroscopic structure: no loop; surface structure: P+F (pearlite + ferrite); structure at 1 / 4 position: P+F (pearlite + ferrite); grain size at 1 / 4 position: 11.5 - 12.5 grades; P (pearlite) content at 1 / 4 position: 37% - 41%; central structure: P+F.

[0022] Furthermore, for the wire rod produced by the high-speed wire rod production of the present invention, the yield strength ≥ 445 Mpa, the tensile strength ≥ 620 Mpa, the elongation after fracture A ≥ 26%, the total elongation at maximum force Agt ≥ 13%, and the strength ratio ≥ 1.40.

[0023] Furthermore, for the hot-rolled ribbed steel bar of the present invention, the yield strength is 445 M - 460 pa, the tensile strength is 625 - 645 Mpa, the elongation after fracture A is 26% - 31%, the total elongation at maximum force Agt is 13.6% - 15.5%, and the strength ratio is 1.40 - 1.42.

[0024] The present invention also provides a method for producing wire rods for high-speed wire rod production. The production method includes: blast furnace hot metal smelting, hot metal desulfurization pretreatment, converter molten steel smelting, billet continuous casting, heating furnace heating, rough rolling, intermediate rolling, pre-finishing rolling, water tank cooling after pre-finishing rolling, finishing rolling, water tank cooling after finishing rolling, reducing, wire laying, air-cooling roller table cooling, coiling, trimming, and bundling;

[0025] Among them, the starting rolling temperature is 930 - 980 °C, the temperature entering the finishing rolling is 900 - 930 °C, the temperature entering the reducing is 840 - 880 °C, the wire laying temperature is 880 - 920 °C (the temperature rise of the steel bar after rolling through the reducing mill is about 40 °C), and all the heat preservation covers are opened.

[0026] The production method adopts single-line rolling. The finished product specifications are φ6mm with a rolling speed of 105 m / s; the finished product specifications are φ8mm with a rolling speed of 90 m / s; the finished product specifications are φ10mm with a rolling speed of 64 m / s; the finished product specifications are φ12mm with a rolling speed of 40 m / s.

[0027] In the production method, the temperature in the heating section is controlled at 1040 - 1100 °C, the soaking section is controlled at 1030 - 1080 °C, the heating time of the steel billet is 80 - 120 minutes, the starting rolling temperature is 930 - 980 °C, the temperature entering the finishing rolling is 900 - 930 °C, the temperature entering the reducing is 840 - 880 °C, and the wire laying temperature is 880 - 920 °C (the temperature rise of the steel bar after rolling through the reducing mill is about 40 °C).

[0028] The present invention does not use water cooling after the reducing mill. By applying the present invention, the fine grain strengthening effect of controlled rolling and controlled cooling can be fully utilized, the usage amount of microalloys such as Nb, V, Ti, etc. can be reduced, and hot rolled ribbed steel bars that meet the standards of hot rolled ribbed steel bars without tempered martensite and sorbite structures can be obtained. The yield strength is ≥445 Mpa, the tensile strength is ≥620 Mpa, the elongation after fracture A≥26%, the total elongation at maximum force Agt≥13%, and the yield to tensile ratio is ≥1.40. The alloy cost per ton of steel is reduced by 85 yuan. At the same time, the amount of alloy manually added to the converter can be reduced, and the labor intensity can be lowered. Specific embodiments

[0029] In order to have a clearer understanding of the technical features, objectives, and effects of the present invention, the present invention will now be described.

[0030] The principle of the present invention is as follows: Microalloys such as Nb, V, Ti, etc. can improve the strength performance of steel bars through solid solution strengthening, fine grain strengthening, precipitation strengthening, etc. Therefore, reducing the usage amount of microalloys such as Nb, V, Ti, etc. will significantly reduce the strength of steel bars. To ensure that the strength of the steel bars still meets the requirements of GB / T 1499.2-2018 "Steel for the Reinforcement of Concrete - Part 2: Hot Rolled Ribbed Bars", other methods are needed to improve the strength of the steel bars. Among them, the controlled rolling and controlled cooling technology can significantly refine the grains and greatly improve the strength of the steel bars.

[0031] Composition design: The chemical composition of plain speed bars (hereinafter referred to as plain bars) is by weight percentage, C: 0.21% - 0.25%, Si: 0.40% - 0.70%, Mn: 0.80% - 1.10%, P≤0.045%, S≤0.045%, and the rest is Fe;

[0032] 1. The present invention sets the starting rolling temperature of high-speed wire at 930 - 980 °C, which can prevent grain growth during the heating process and refine austenite grains; during the rolling process, the temperature rise of the rolled piece is obvious. In order to prevent grain growth caused by the temperature rise during the rolling process and taking into account that the roll rings are prone to bursting when the rolling temperature is too low, 50% - 75% of the water is turned on for both of the 2 water tanks before entering the finishing mill to control the temperature of the rolled piece entering the finishing mill at 900 - 930 °C, and 10% - 30% of the water is turned on for all of the 3 water tanks before entering the reducing mill to control the temperature of the rolled piece entering the reducing mill at 840 - 880 °C, and the laying head temperature is 880 - 920 °C (the temperature rise of the steel bar after being rolled by the reducing mill is about 40 °C); all the heat preservation covers are opened, and different numbers of fans are turned on according to different specifications, which can accelerate the cooling speed, refine the grains, and improve the strength.

[0033] 2. The high-speed wire rolling specifications are φ6 - φ12mm, with single-line rolling. The process is as follows: blast furnace hot metal smelting → hot metal desulfurization pretreatment → converter steelmaking → billet continuous casting → heating furnace heating → rough rolling → medium rolling → pre-finishing rolling → cooling in the water tank after pre-finishing rolling → finishing rolling → cooling in the water tank after finishing rolling → reducing → wire laying → cooling on the air-cooling roller table → coiling → trimming, bundling, weighing, tagging, and warehousing.

[0034] 3. After the hot metal is blown in the BOF, the steel is tapped using a slide gate slag stopper, and then alloy and deoxidizer are added to make the C content 0.21% - 0.25%, the Si content 0.40% - 0.70%, the Mn content 1.10% - 1.30%, and the P and S contents ≤0.045%. Then it is sent to the argon station for argon blowing. Appropriate secondary cooling parameters are selected for continuous casting, and the whole-process protected casting process is used for pouring.

[0035] 4. The billets cast by continuous casting are heated in the heating furnace. The temperature in the heating section is controlled at 1040 - 1100°C, and the soaking section is controlled at 1030 - 1080°C. The heating time of the steel billets is 80 - 120 minutes. The starting rolling temperature is 930 - 980°C, the temperature entering the finishing rolling is 900 - 930°C, the temperature entering the reducing is 840 - 880°C, and the wire laying temperature is 880 - 920°C (the temperature rise of the steel bar after rolling through the reducing mill is about 40°C, and there is no water cooling after the reducing mill). The heat preservation covers are all opened, and different numbers of fans are turned on according to different specifications. Among them, for the φ6mm wire rod, 1 - 2# fans are turned on with a 100% air volume; for the φ8mm wire rod, 1 - 4# fans are turned on with a 100% air volume; for the φ10mm wire rod, 1 - 6# fans are turned on with a 100% air volume; for the φ12mm wire rod, 1 - 7# fans are turned on with a 100% air volume.

[0036] Table 1: Composition of Steel in Each Example

[0037]

[0038] Table 2: Heating Process of Steel in Each Example

[0039]

[0040] Table 3: Rolling Process of Steel in Each Example

[0041]

[0042] Table 4: Mechanical Properties of Steel in Each Example

[0043]

[0044] A is the elongation after fracture, unit: %, Agt is the total elongation at maximum force, unit: %

[0045] Table 5: Metallographic Structure of Steel in Each Example

[0046]

[0047] As shown in Table 1 - Table 5, it can be seen from Examples 1 - 4 that through reasonable control of chemical composition and by adopting appropriate rolling processes, the present invention can reduce the usage amount of micro - alloys such as Nb, V, Ti, etc., lower the production cost, and at the same time enable the wire rod to have good mechanical properties, and the metallographic structure meets the requirements of GB / T 1499.2 - 2018.

[0048] The above - mentioned is only the schematic specific implementation manner of the present invention and is not used to limit the scope of the present invention. The various components of the present invention can be combined with each other under the condition of no conflict. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A wire rod for high-speed wire rod production, characterized in that, The composition of the wire rod produced by high-speed wire rod production, by weight percentage, is as follows: C: 0.21% - 0.25%, Si: 0.40% - 0.70%, Mn: 0.80% - 1.10%, P ≤ 0.045%, S ≤ 0.045%, and the rest is Fe; The specifications of the hot-rolled ribbed steel bars are φ6 - φ12mm; The production method uses single-line rolling, and the rolling speed is 35 - 110 m / s; The production method includes: blast furnace hot metal smelting, hot metal desulfurization pretreatment, converter steelmaking, billet continuous casting, heating furnace heating, rough rolling, medium rolling, pre-finishing rolling, water tank cooling after pre-finishing rolling, finishing rolling, water tank cooling after finishing rolling, reducing sizing, wire laying, air-cooling roller table cooling, coiling, trimming, and bundling; The temperature in the heating section is controlled at 1040 - 1100°C, the soaking section is controlled at 1030 - 1080°C, and the heating time of the steel billet is 80 - 120 minutes; Among them, the starting rolling temperature is 930 - 980°C, the temperature entering the finishing rolling is 900 - 930°C, the temperature entering the reducing sizing is controlled at 840 - 880°C, and the wire laying temperature is 880 - 920°C; The metallographic structure is as follows: macroscopic structure: no loop; surface structure: pearlite + ferrite; structure at 1 / 4 position: pearlite + ferrite; grain size at 1 / 4 position: 11.5 - 12.5 grades; pearlite content at 1 / 4 position: 37% - 41%; central structure: P + F; The wire rod has good mechanical properties, and the metallographic structure meets the requirements of GB / T 1499.2 - 2018.

2. The wire rod for high-speed wire rod production according to claim 1, characterized in that, After the hot metal is blown in the BOF, it is tapped using a slide gate slag stopper, and then alloy and deoxidizer are added to make the C content 0.21% - 0.25%, the Si content 0.40% - 0.70%, the Mn content 0.80% - 1.10%, and the P and S contents ≤ 0.045%. Then it is sent to the argon station for argon blowing, and the whole-process protected casting process is used for casting.

3. The wire rod for high-speed wire rod production according to claim 1, characterized in that, The finished product specification is φ6mm, and the rolling speed is 105m / s; Turn on the 1 - 2# fans, and the air volume is 100%.

4. The wire rod for high-speed wire rod production according to claim 1, characterized in that, The finished product specification is φ8mm, and the rolling speed is 90m / s; Turn on the 1 - 4# fans, and the air volume is 100%.

5. The wire rod for high-speed wire rod production according to claim 1, characterized in that, The finished product specification is φ10mm, and the rolling speed is 64m / s; Turn on the 1 - 6# fans, and the air volume is 100%.

6. The wire rod for high-speed wire rod production according to claim 1, characterized in that, The finished product specification is φ12mm, and the rolling speed is 40m / s. Turn on the 1 - 7# fans, and the air volume is 100%.

7. The wire rod for high-speed wire rod production according to claim 1, characterized in that, The composition of the hot-rolled ribbed steel bars is: C: 0.22%, Si: 0.48%, Mn: 0.88%, P: 0.027%, S: 0.018%, and the rest is Fe.

8. The wire rod for high-speed wire rod production according to claim 1, characterized in that, The starting rolling temperature is controlled at 956°C, the temperature entering the finishing rolling is 912°C, the temperature entering the reducing sizing is 860°C, the wire laying temperature is 894°C, and the temperature after air cooling is 709°C.

9. The wire rod for high-speed wire rod production according to claim 1, characterized in that, The starting rolling temperature is controlled at 967°C, the temperature entering the finishing rolling is 912°C, the temperature entering the reducing sizing is 849°C, the wire laying temperature is 882°C, and the temperature after air cooling is 579°C.

10. The wire rod for high-speed wire rod production according to claim 1, characterized in that, C: 0.23%, Si: 0.47%, Mn: 0.91%, P: 0.034%, S: 0.032%, and the rest is Fe.

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