Method for producing wire rod from high-speed wire rod

Abstract

The invention provides a method for producing a wire rod from a high-speed wire rod. The method comprises the following steps: controlling 0.21-0.25% of C, 0.40-0.70% of Si, 0.80-1.10% of Mn, less than or equal to 0.045% of P, less than or equal to 0.045% of S and the balance of Fe; the production method comprises the steps of rough rolling, intermediate rolling, pre-finish rolling, water tank and recovery section after pre-finish rolling, finish rolling, water tank and recovery section after finish rolling, diameter reducing, spinning, air cooling roller bed cooling, coil collecting, trimming and bundling. The temperature of a heating section is controlled to be 1040-1100 DEG C, the temperature of a soaking section is controlled to be 1030-1080 DEG C, and the heating time of the steel billet is 80-120 minutes; the initial rolling temperature is 930-980 DEG C, the finish rolling temperature is 900-930 DEG C, the reducing temperature is controlled at 840-880 DEG C, the spinning temperature is 880-920 DEG C, and a heat preservation cover is completely opened.

Description

[0001] This invention is a divisional application, the parent case name is: Wire rod for high-speed wire production, application number: 2022105947483, application date: May 27, 2022. Technical Field

[0002] The present invention relates to the field of steel rolling, and in particular to a method for producing wire rods from high-speed wire rods. Background Art

[0003] Wire rods made from high-speed wire rods 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 be primarily ferrite plus pearlite, and tempered martensite should not appear on the base circle.

[0004] Currently, most steel mills increase the strength of steel bars by adding microalloys such as Nb, V, and Ti to steel through solid solution strengthening, fine grain strengthening, and precipitation strengthening. However, the addition of microalloys such as Nb, V, and Ti will significantly increase alloy costs and reduce corporate profits.

[0005] In summary, the existing technology has the following problem: how to produce wire rods for high-speed wire production that meet the standards for hot-rolled ribbed steel bars without adding microalloys such as Nb, V, and Ti and without water cooling after rolling. Summary of the Invention

[0006] The present invention provides a wire rod for high-speed wire production (especially a hot-rolled ribbed steel wire rod for high-speed wire production) to solve the problem of producing hot-rolled ribbed steel bars with qualified performance without adding microalloys such as Nb, V, and Ti and without water cooling after rolling.

[0007] To this end, the present invention proposes a wire rod for high-speed wire production, wherein the components of the wire rod for high-speed wire production are, by weight percentage, C: 0.21% to 0.25%, Si: 0.40% to 0.70%, Mn: 0.80% to 1.10%, P≤0.045%, S≤0.045%, and the remainder is Fe;

[0008] The specifications of hot rolled ribbed steel bars are

[0009] The production method adopts single-line rolling, and the finished product specifications are The rolling speed is 105m / s; the finished product specifications are The rolling speed is 90m / s; the finished product specifications are The rolling speed is 64m / s; the finished product specifications are The rolling speed is 40m / s.

[0010] The production method comprises: blast furnace molten iron smelting, molten iron desulfurization pretreatment, converter molten steel smelting, billet continuous casting, heating in a heating furnace, rough rolling, intermediate rolling, pre-finishing rolling, water tank and recovery section after pre-finishing rolling, finishing rolling, water tank and recovery section after finishing rolling, diameter reduction, wire laying, air-cooled roller cooling, coiling, trimming, and bundling; the water tank after finishing rolling controls the temperature of the rolling process to prevent excessive temperature rise during the rolling process and grain growth, and no water cooling is required after the diameter reducing mill;

[0011] Among them, the starting rolling temperature is 930-980℃, the finishing rolling temperature is 900-930℃, the reducing temperature is controlled at 840-880℃, the wire drawing temperature is 880-920℃ (the temperature rise of the steel bar after rolling through the reducing mill is about 40℃, and no water cooling is required after the reducing mill), and the insulation covers are all opened.

[0012] Furthermore, after BOF blowing, the molten iron is tapped using a slide plate to block slag, and then alloys and deoxidizers are added to make the C content 0.21% to 0.25%, the Si content 0.40% to 0.70%, the Mn content 0.80% to 1.10%, and the P and S contents ≤ 0.045%. The molten iron is then sent to an argon station for argon blowing and cast using a full-process protective casting process.

[0013] Furthermore, the temperature of the heating section is controlled at 1040-1100°C, the soaking section is controlled at 1030-1080°C, the billet heating time is 80-120 minutes, the starting rolling temperature is 930-980°C, the finishing rolling temperature is 900-930°C, the reducing temperature is 840-880°C, and the spinning temperature is 880-920°C (the temperature rise of the steel bar after passing through the reducing mill is about 40°C).

[0014] Furthermore, For coiling, open 1-2# fans with 100% air volume.

[0015] Furthermore, For coiling, open 1-4# fans with 100% air volume.

[0016] Furthermore, For coiling, open 1-6# fan with 100% air volume.

[0017] Furthermore, For wire rod, open 1-7# fan with 100% air volume.

[0018] Furthermore, the 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 remainder is Fe.

[0019] Furthermore, the starting rolling temperature is controlled at 956°C, the finishing rolling temperature is 912°C, the reducing temperature is 860°C, the spinning temperature is 894°C, and the temperature after air cooling is 709°C.

[0020] Furthermore, the starting rolling temperature is controlled at 967°C, the finishing rolling temperature is 912°C, the reducing temperature is 849°C, the spinning temperature is 882°C, and the temperature after air cooling is 579°C.

[0021] Further, C: 0.23%, Si: 0.47%, Mn: 0.91%, P: 0.034%, S: 0.032%, and the remainder is Fe.

[0022] Furthermore, the metallographic structure of the wire rod produced by the high-speed wire rod of the present invention is as follows: macrostructure: no ring; surface structure: P+F (pearlite + ferrite); structure at 1 / 4: P+F (pearlite + ferrite); grain size at 1 / 4: 11.5-12.5 level; P (pearlite) content at 1 / 4: 37%-41%; center structure: P+F.

[0023] Furthermore, the wire rod produced by the high-speed wire rod of the present invention has a yield strength ≥445 MPa, a tensile strength ≥620 MPa, an elongation after fracture A ≥26%, a total elongation at maximum force Agt ≥13%, and a strength-to-yield ratio ≥1.40.

[0024] Furthermore, the hot-rolled ribbed steel bar of the present invention has a yield strength of 445M-460Mpa, a tensile strength of 625-645Mpa, an elongation after fracture A of 26%-31%, a total elongation at maximum force Agt of 13.6%-15.5%, and a strength-to-yield ratio of 1.40-1.42.

[0025] The present invention also provides a method for producing wire rods from high-speed wire rods, the production method comprising: blast furnace molten iron smelting, molten iron desulfurization pretreatment, converter molten steel smelting, billet continuous casting, heating in a heating furnace, rough rolling, intermediate rolling, pre-finishing rolling, water tank and recovery section after pre-finishing rolling, finishing rolling, water tank and recovery section after finishing rolling, diameter reduction, wire laying, air-cooled roller cooling, coiling, trimming, and bundling;

[0026] Among them, the starting rolling temperature is 930-980℃, the finishing rolling temperature is 900-930℃, the reducing temperature is 840-880℃, the spinning temperature is 880-920℃ (the temperature rise of the steel bar after rolling through the reducing mill is about 40℃), and the insulation covers are all opened.

[0027] The production method adopts single-line rolling, and the finished product specifications are The rolling speed is 105m / s; the finished product specifications are The rolling speed is 90m / s; the finished product specifications are The rolling speed is 64m / s; the finished product specifications are The rolling speed is 40m / s.

[0028] In the production method, the temperature of the heating section is controlled at 1040-1100°C, the soaking section is controlled at 1030-1080°C, the billet heating time is 80-120 minutes, the starting rolling temperature is 930-980°C, the finishing rolling temperature is 900-930°C, the reducing temperature is 840-880°C, and the spinning temperature is 880-920°C (the temperature rise of the steel bar after rolling through the reducing mill is about 40°C).

[0029] This invention eliminates the need for water cooling after the reducing mill. This method fully utilizes the grain-refining strengthening effects of controlled rolling and controlled cooling, reducing the use of microalloys such as Nb, V, and Ti. The resulting hot-rolled ribbed steel bar, devoid of tempered martensite and sorbite, meets the standards for hot-rolled ribbed steel bars. The steel bar exhibits yield strength ≥445 MPa, tensile strength ≥620 MPa, elongation after fracture (A) ≥26%, total elongation at maximum force (Agt) ≥13%, and strength-to-yield ratio ≥1.40. This reduces alloying costs by 85 yuan per ton of steel, while also reducing the amount of alloy input into the converter and lowering labor intensity. DETAILED DESCRIPTION

[0030] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the present invention is now described.

[0031] The principle behind this invention is that microalloys such as Nb, V, and Ti can improve the strength of steel bars through solid solution strengthening, grain refinement, and precipitation strengthening. Therefore, reducing their use significantly reduces the strength of the bars. To ensure that the strength of the bars still meets the requirements of GB / T 1499.2-2018, "Steel for Reinforced Concrete - Part 2: Hot-rolled Ribbed Bars," other methods are necessary to increase the strength of the bars. Among these, controlled rolling and controlled cooling technology can significantly refine the grain size, significantly improving the strength of the bars.

[0032] Composition design: The chemical composition of ordinary speed bars (hereinafter referred to as ordinary bars) is based on weight percentage: C: 0.21% to 0.25%, Si: 0.40% to 0.70%, Mn: 0.80% to 1.10%, P≤0.045%, S≤0.045%, and the rest is Fe;

[0033] 1. The present invention sets the high-speed wire rolling starting temperature at 930-980°C, which can prevent grain growth during the heating process and refine the austenite grains. The temperature of the rolled piece rises significantly during the rolling process. In order to prevent grain growth caused by the temperature rise during the rolling process and to take into account the easy collapse of the roll rings due to too low rolling temperature, the two water tanks before entering the finishing mill are filled with 50%-75% water to control the temperature of the rolled piece entering the finishing rolling at 900-930°C. The three water tanks before entering the reducing mill are filled with 10%-30% water to control the temperature of the rolled piece entering the reducing mill at 840-880°C and the spinning temperature at 880-920°C (the temperature rise of the steel bar after rolling in 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 to accelerate the cooling speed, refine the grains, and improve the strength.

[0034] 2. High-speed wire rolling specifications are Single-line rolling is adopted, and the process is: blast furnace molten iron smelting → molten iron desulfurization pretreatment → converter molten steel smelting → billet continuous casting → heating in heating furnace → rough rolling → intermediate rolling → pre-finishing rolling → water tank and recovery section after pre-finishing rolling → finishing rolling → water tank and recovery section after finishing rolling → diameter reducing → wire laying → air-cooled roller cooling → coiling → trimming, bundling, weighing, labeling, and warehousing.

[0035] 3. After BOF blowing, the molten iron is tapped with a slide plate to block the slag. Then, alloy and deoxidizer are added to adjust the C content to 0.21%-0.25%, the Si content to 0.40%-0.70%, the Mn content to 1.10%-1.30%, and the P and S contents to ≤0.045%. The molten iron is then sent to the argon station for argon blowing. Appropriate secondary cooling parameters are selected for continuous casting, and the casting is carried out using a full-process protective casting process.

[0036] 4. The billet casted by continuous casting is heated in a heating furnace. The temperature of the heating section is controlled at 1040-1100℃, the soaking section is controlled at 1030-1080℃, the billet heating time is 80-120 minutes, the starting rolling temperature is 930-980℃, the finishing rolling temperature is 900-930℃, the reducing temperature is 840-880℃, and the wire drawing temperature is 880-920℃ (the temperature rise of the steel bar after the reducing mill is about 40℃, and the reducing mill is not used for water cooling). All the insulation covers are opened, and different numbers of fans are turned on according to different specifications. For wire rod, open 1-2# fans and set the air volume to 100%; Wire rod turns on 1-4# fans, air volume 100%; Wire rod turns on 1-6# fans, air volume 100%; For wire rod, open 1-7# fan with 100% air volume.

[0037] Table 1: Composition of steels in various examples

[0038] Examples production line Specifications / mm C / ％ Si / % Mn / % P / ％ S / ％ Example 1 High Line Φ6 0.22 0.45 0.88 0.027 0.018 Example 2 High Line Φ8 0.23 0.42 0.94 0.026 0.024 Example 3 High Line Φ10 0.23 0.47 0.91 0.034 0.032 Example 4 High Line Φ12 0.23 0.45 0.89 0.030 0.029

[0039] Table 2: Heating process of steel in various examples

[0040]

[0041]

[0042] Table 3: Rolling process of steel in various examples

[0043]

[0044] Table 4: Mechanical properties of steels in various examples

[0045] Examples production line Specification Yield strength MPa Tensile strength Mpa A(％) Agt(%) Strength-to-yield ratio Example 1 High Line Φ6 460 645 31 14.1 1.40 Example 2 High Line Φ8 455 640 28 13.6 1.41 Example 3 High Line Φ10 460 655 26 15.5 1.42 Example 4 High Line Φ12 445 625 28 14.3 1.40

[0046] A is the elongation after fracture, unit: %, Agt is the maximum total elongation, unit: %

[0047] Table 5: Metallographic structure of steels in various examples

[0048] Examples production line Specification Macro-organization Surface tissue 1 / 4 tissue Grain size at 1 / 4 P content at 1 / 4 Central Organization Example 1 Φ6 No ring P+F P+F 12.5 40％ P+F Φ6 Example 2 Φ8 No ring P+F P+F 12.0 39％ P+F Φ8 Example 3 Φ10 No ring P+F P+F 12.0 42％ P+F Φ10 Example 4 Φ12 No ring P+F P+F 11.5 37％ P+F Φ12

[0049] As shown in Tables 1 to 5, it can be seen from Examples 1 to 4 that the present invention can reduce the use of microalloys such as Nb, V, and Ti, reduce production costs, and at the same time allow the wire rod to have better mechanical properties, and the metallographic structure meets the requirements of GB / T 1499.2-2018 through reasonable chemical composition control and the adoption of a suitable rolling process.

[0050] The above description is merely an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. The various components of the present invention may be combined with each other without conflict, and any equivalent changes and modifications made by a person skilled in the art without departing from the concept and principles of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for producing wire rods from high-speed wire rods, characterized in that: The composition of the wire rod produced by high-speed wire rod is, by weight percentage, C: 0.21% to 0.25%, Si: 0.40% to 0.70%, Mn: 0.80% to 1.10%, P≤0.045%, S≤0.045%, and the rest is Fe; The specifications of hot rolled ribbed steel bars are The method for producing wire rod adopts single-line rolling with a rolling speed of 35-110 m / s. The method for producing wire rod comprises: blast furnace molten iron smelting, molten iron desulfurization pretreatment, converter molten steel smelting, billet continuous casting, heating in a heating furnace, rough rolling, intermediate rolling, pre-finishing rolling, water tank and recovery section after pre-finishing rolling, finishing rolling, water tank and recovery section after finishing rolling, diameter reduction, wire laying, air-cooled roller cooling, coiling, trimming, and bundling; The temperature of the heating section is controlled at 1040-1100°C, the soaking section is controlled at 1030-1080°C, and the billet heating time is 80-120 minutes; Among them, the starting rolling temperature is 930-980℃, the finishing rolling temperature is 900-930℃, the reducing temperature is controlled at 840-880℃, the spinning temperature is 880-920℃, and the insulation covers are all opened.

2. The method for producing wire rod from high-speed wire rod according to claim 1, wherein: After BOF blowing, the molten iron is tapped using a slide plate to block slag, and then alloys and deoxidizers are added to make the C content 0.21% to 0.25%, the Si content 0.40% to 0.70%, the Mn content 0.80% to 1.10%, and the P and S contents ≤ 0.045%. It is then sent to the argon station for argon blowing and cast using a full-process protective casting process.

3. The method for producing wire rod from high-speed wire rod according to claim 1, wherein: The 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 remainder is Fe.

4. The method for producing wire rod from high-speed wire rod according to claim 1, wherein: Finished product specifications are The rolling speed is 105m / s; the 1-2# fans are turned on, with an air volume of 100%.

5. The method for producing wire rod from high-speed wire rod according to claim 1, wherein: Finished product specifications are The rolling speed is 90m / s; fans 1-4# are turned on with an air volume of 100%.

6. The method for producing wire rod from high-speed wire rod according to claim 1, wherein: Finished product specifications are The rolling speed is 64m / s; the 1-6# fan is turned on, and the air volume is 100%.

7. The method for producing wire rod from high-speed wire rod according to claim 1, wherein: Finished product specifications are The rolling speed is 40m / s and the 1-7# fan is turned on with an air volume of 100%.

8. The method for producing wire rod from high-speed wire rod according to claim 1, wherein: The starting rolling temperature is controlled at 956℃, the finishing rolling temperature is 912℃, the reducing temperature is 860℃, the wire drawing temperature is 894℃, and the temperature after air cooling is 709℃.

9. The method for producing wire rod from high-speed wire rod according to claim 1, wherein: The starting rolling temperature is controlled at 967℃, the finishing rolling temperature is 912℃, the reducing temperature is 849℃, the wire drawing temperature is 882℃, and the temperature after air cooling is 579℃.

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