Production method of hot-rolled ribbed steel bar for 800MPa-grade high-strength anchor rod

Abstract

The invention discloses a production method of a hot-rolled ribbed bar for an 800MPa-grade high-strength anchor rod. The production method comprises the following steps: converter smelting, LF refining, continuous casting, heating of a casting blank heating furnace, round steel rolling and heat treatment. The hot-rolled ribbed steel bar comprises the following chemical components in percentage by mass: 0.30%-0.40% of C, 0.60%-0.70% of Si, 1.50%-1.70% of Mn, less than or equal to 0.025% of P, less than or equal to 0.025% of S, 0.15%-0.25% of V and the balance of Fe and inevitable trace impurities, and the total mass fraction is 100%. The V alloying principle is utilized, on the premise that the production cost is reduced, the mechanical property of the hot-rolled round steel is remarkably improved, and therefore the hot-rolled ribbed steel bar for the 800 MPa-grade high-strength anchor rod is produced, the overall service life of the mining anchor rod is remarkably prolonged, and the safety of the mining anchor rod is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of smelting and rolling, and in particular relates to a production method of hot-rolled ribbed steel bars for 800MPa-grade high-strength anchor rods. Background Art

[0002] At present, the steel industry has been able to stably produce high-strength and high-toughness hot-rolled ribbed steel bars through microalloying, precise rolling and cooling control and other technical means. 800MPa-grade mining anchor steel bars can improve strength and toughness by adding microalloying elements such as vanadium, titanium, and niobium, and control their organizational properties by optimizing rolling and heat treatment processes to ensure good tensile strength, fatigue resistance and corrosion resistance in complex mining environments. With the increase in mining depth and the improvement of safety requirements, traditional steel bars with lower strength grades can no longer meet the anchoring requirements under high stress and high load environments. 800MPa-grade hot-rolled ribbed steel bars can not only improve the bearing capacity and safety of the anchoring system, but also reduce the use of steel bars and reduce the construction cost of mine support projects. In addition, high-strength steel bars that meet the trend of green environmental protection can help mining companies achieve energy conservation and emission reduction goals and improve resource utilization efficiency. Therefore, the development of this product by steel mills will be widely used, not only to occupy the high-end market of mining anchor steel bars, but also to provide important support for mine safety assurance, and have broad commercial prospects.

[0003] Publication No. CN 117512477 A introduces a method for producing 650MPa anchor steel bars, which produces an anchor steel bar with a yield strength of 650MPa by adding alloys such as Cu, Ni, Cr, and V. This patent is to produce a mining anchor hot-rolled ribbed steel bar with a yield strength of 800MPa while reducing costs by adding V elements.

[0004] Publication No. CN 112226698 A introduces a method for producing a 700MPa grade high-strength anchor rod hot-rolled ribbed steel bar, which produces an anchor rod steel bar with a yield strength of 700MPa by adding alloying element V. This patent is to produce a higher performance mining anchor rod hot-rolled ribbed steel bar with a yield strength of 800MPa by adding a considerable amount of V element and then through a suitable heat treatment system.

[0005] Publication No. CN 116103654 A introduces an 800MPa anchor bar, which is produced by adding alloy element Cr and smelting in an electric furnace to produce an anchor bar with a yield strength of 800MPa. This patent is to produce a mining anchor hot-rolled ribbed steel bar with a yield strength of 800MPa and better impact toughness by adding a small amount of V element and smelting in a converter at a lower cost. Summary of the invention

[0006] The purpose of the present invention is to provide a production method of hot-rolled ribbed steel bars for 800MPa high-strength anchor rods, which utilizes the V alloying principle to significantly improve the mechanical properties of hot-rolled round steel while reducing production costs, thereby producing hot-rolled ribbed steel bars for 800MPa high-strength anchor rods, thereby significantly improving the overall life and safety of mining anchor rods.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for producing a hot-rolled ribbed steel bar for an 800MPa high-strength anchor rod, comprising:

[0009] Converter smelting, LF refining, continuous casting, billet heating furnace heating, round steel rolling, heat treatment; among them:

[0010] Combined blowing converter smelting ensures that the smelting materials are dry to avoid water vapor entering the steel to produce white spots; requirements [P] < 0.012%, [S] < 0.030%; nitrogen and argon blowing at the bottom of the converter ensures that the carbon is hit once and avoids post-blowing, and the end point carbon is controlled ≤ 0.10%, reducing the oxidation of molten steel and reducing decarburization; the end point [P] ≤ 0.020%; slag blocking during steel tapping, and argon blowing throughout the steel tapping process;

[0011] During the refining of white slag, the molten steel must not be exposed; the calcium wire is used to deform the inclusions to avoid nozzle nodules; no slag is added after the calcium wire is fed to purify the molten steel, and the soft blowing time is ≥10min to ensure that the inclusions fully float; ferrovanadium is added in the later stage of refining;

[0012] During continuous casting, the molten steel outside the long nozzle cannot be exposed to prevent secondary oxidation of the molten steel; ensure that the crystallizer is centered, use weak cooling for secondary cooling, control the cooling water distribution in the secondary cooling zone to 0.35-0.65L / kg, and keep the casting speed constant; use electromagnetic stirring to improve the surface quality of the ingot;

[0013] The billet heating temperature is 1080~1120℃, the allowable temperature difference is ≤50℃, the total heating time is controlled to be 2h, the rolling temperature is 1030~1050℃, prevent overheating, overburning and decarburization, and heat up slowly to ensure uniform billet heating temperature and reduce temperature difference;

[0014] The heat treatment system is 830-880℃ normalizing and 500-550℃ tempering;

[0015] The mass percentage of the chemical composition of the hot-rolled ribbed steel bar includes: C 0.30%-0.40%, Si 0.60%-0.70%, Mn 1.50%-1.70%, P≤0.025%, S≤0.025%, V 0.15-0.25%, and the rest is Fe and inevitable trace impurities, with a total mass fraction of 100%.

[0016] Furthermore, pay attention to the conditions of the rollers, steel turning machines, guide plates, roller tables and cover plates, and ensure that they are smooth and have no sharp edges to avoid scratches and bumps on the surface of the rolled product. The specification of the rolled product is φ20mm.

[0017] Furthermore, the chemical composition of the hot-rolled ribbed steel bar includes by weight percentage: C 0.35%, Si 0.65%, Mn 1.55%, P 0.015%, S 0.005%, V 0.20%, and the rest is Fe and inevitable trace impurities, with a total weight fraction of 100%.

[0018] Furthermore, the chemical composition of the hot-rolled ribbed steel bar includes by weight percentage: C 0.34%, Si 0.66%, Mn 1.53%, P 0.014%, S 0.006%, V 0.19%, and the rest is Fe and inevitable trace impurities, with a total weight fraction of 100%.

[0019] Furthermore, the mass percentage of the chemical composition of the hot-rolled ribbed steel bar includes: C 0.36%, Si 0.63%, Mn 1.58%, P 0.016%, S 0.004%, V 0.22%, and the rest is Fe and inevitable trace impurities, with a total mass fraction of 100%.

[0020] Compared with the prior art, the beneficial technical effects of the present invention are:

[0021] (1) Through V micro-alloying and precise control of smelting and rolling processes, the 800MPa grade hot-rolled ribbed steel bars produced by the present invention have excellent strength and toughness, can adapt to the high stress conditions in the complex environment of mines, and significantly improve the service life and safety of mining anchors. (2) Under the premise of ensuring the high strength of the steel bars, by reasonably optimizing the addition of alloy elements, especially the V element, the present invention effectively reduces the production cost and has good economic benefits. (3) Compared with traditional steel bar production, the present invention reduces the use of steel bars and reduces the material consumption of mine support projects, which is in line with the green and environmental protection trend of energy conservation and emission reduction. DETAILED DESCRIPTION

[0022] Embodiment 1:

[0023] The present invention provides a method for producing a hot-rolled ribbed steel bar for an 800MPa high-strength anchor rod, wherein the production process is carried out according to the following steps:

[0024] (1) Combined blowing converter smelting ensures that the smelting materials are dry to prevent water vapor from entering the steel and producing white spots; control [P] 0.009%, [S] 0.020%; switch the converter bottom blowing nitrogen and argon to ensure that the carbon is pulled once and avoid post-blowing, the end point carbon is controlled at 0.07%, and the end point [P] is 0.011%; slag is blocked during steel tapping, and argon is blown throughout the steel tapping process;

[0025] (2) During the refining of white slag, the molten steel must not be exposed during the whole process; the calcium feeding line is used to deform the inclusions to avoid nodules; no slag is added after the calcium feeding line to purify the molten steel, and the soft blowing time is 15 minutes to ensure that the inclusions fully float;

[0026] (3) Weak cooling is used in the secondary cooling zone, the cooling water distribution volume in the secondary cooling zone is 0.5 L / kg, and the constant pulling speed is 0.70 m / min; electromagnetic stirring is used to improve the surface quality of the ingot, and the electromagnetic stirring parameters are 320 A / 4 Hz;

[0027] (4) The billet heating temperature is 1100°C, the total heating time is controlled to be 2h, and the rolling temperature is 1050°C;

[0028] (5) The finished product specification is φ20mm. The heat treatment system is 830℃ normalizing and 500℃ tempering.

[0029] Embodiment 2:

[0030] The present invention provides a method for producing a hot-rolled ribbed steel bar for an 800MPa high-strength anchor rod, wherein the production process is carried out according to the following steps:

[0031] (1) Combined blowing converter smelting ensures that the smelting materials are dry to prevent water vapor from entering the steel and producing white spots; control [P] 0.010%, [S] 0.023%; switch the converter bottom blowing nitrogen and argon to ensure that the carbon is pulled once and avoid post-blowing, the end point carbon is controlled at 0.06%, and the end point [P] is 0.009%; slag is blocked during steel tapping, and argon is blown throughout the steel tapping process;

[0032] (2) During the refining of white slag, the molten steel must not be exposed during the whole process; the calcium feeding line is used to deform the inclusions to avoid nodules; no slag is added after the calcium feeding line to purify the molten steel, and the soft blowing time is 15 minutes to ensure that the inclusions fully float;

[0033] (3) Weak cooling is adopted for the secondary cooling, the cooling water distribution volume in the secondary cooling zone is 0.45L / kg, and the constant pulling speed is 0.70m / min; electromagnetic stirring is used to improve the surface quality of the ingot, and the electromagnetic stirring parameters are 320A / 4Hz;

[0034] (4) Billet heating temperature is 1110°C, total heating time is controlled to be 2h10min, and rolling temperature is 1040°C;

[0035] (5) The finished product specification is φ20mm. The heat treatment system is 880℃ normalizing and 550℃ tempering.

[0036] Embodiment 3:

[0037] The present invention provides a method for producing a hot-rolled ribbed steel bar for an 800MPa high-strength anchor rod, wherein the production process is carried out according to the following steps:

[0038] (1) Combined blowing converter smelting ensures that the smelting materials are dry to prevent water vapor from entering the steel and producing white spots; control [P] 0.011%, [S] 0.019%; switch the converter bottom blowing nitrogen and argon to ensure that the carbon is pulled once and avoid post-blowing, the end point carbon is controlled at 0.08%, and the end point [P] 0.010%; slag is blocked during steel tapping, and argon is blown throughout the steel tapping process;

[0039] (2) During the refining of white slag, the molten steel must not be exposed during the whole process; the calcium feeding line is used to deform the inclusions to avoid nodules; no slag is added after the calcium feeding line to purify the molten steel, and the soft blowing time is 15 minutes to ensure that the inclusions fully float;

[0040] (3) Weak cooling is adopted in the secondary cooling zone, the cooling water distribution volume in the secondary cooling zone is 0.55L / kg, and the constant pulling speed is 0.70m / min; electromagnetic stirring is used to improve the surface quality of the ingot, and the electromagnetic stirring parameter is 320A / 4Hz;

[0041] (4) Billet heating temperature is 1090°C, total heating time is controlled to be 110 min, and rolling temperature is 1030°C;

[0042] (5) The finished product specification is φ20mm. The heat treatment system is 850℃ normalizing and 530℃ tempering.

[0043] Comparative Example 1:

[0044] Except that the chemical composition does not contain V, the other processes of this comparative example are the same as those of Example 1.

[0045] Comparative Example 2:

[0046] Except for the heat treatment system, the other processes of this comparative example are the same as those of Example 1. The heat treatment system of this comparative example is normalizing at 930°C and tempering at 530°C.

[0047] Comparative Example 3:

[0048] Except for the heat treatment system, the other processes of this comparative example are the same as those of Example 1. The heat treatment system of this comparative example is to directly temper at 500°C without normalizing.

[0049] Table 1 shows the chemical compositions of three embodiments and three comparative examples of the present invention, and Table 2 and Table 3 further illustrate the present invention.

[0050] Table 1 Chemical composition of each example of hot-rolled ribbed steel bars for 800MPa grade high-strength anchor rods (mass percentage / %)

[0051]

[0052]

[0053] Table 2 Non-metallic inclusions and austenite grain size of various examples of hot-rolled ribbed steel bars for 800MPa high-strength anchor rods

[0054]

[0055] Table 3 Mechanical properties of various examples of hot-rolled ribbed steel bars for 800MPa grade high-strength anchor rods

[0056]

[0057] As can be seen from Tables 1 to 3, (1) the mechanical properties of the present invention are significantly better than those of the embodiments; (2) the present invention reduces the use of expensive alloying elements and reduces production costs by microalloying (rational addition of V element) and precise process control while maintaining high strength and toughness. In Comparative Example 1, no V element is added, resulting in insufficient material performance, while the heat treatment process of Comparative Examples 2 and 3 is unreasonable, affecting the comprehensive performance of the material and the cost control effect; (3) The non-metallic inclusion content of the embodiments is relatively small and well controlled, especially the inclusion content of A coarse and B fine in Example 2 is 0, which indicates that there are fewer inclusions, the cleanliness of the steel is higher, and the fatigue resistance and service life of the material are further improved. In the comparative examples, such as Comparative Example 1, there are obviously more inclusions, especially B coarse and C coarse, which leads to a decrease in material performance and a shortened service life.

[0058] Through comparative analysis, the embodiments show significant performance improvement compared with the comparative examples, especially in terms of mechanical properties and steel cleanliness. The above technical solutions demonstrate the innovation and superiority of the present invention.

[0059] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for producing hot-rolled ribbed steel bars for 800MPa grade high-strength anchor rods, characterized in that: include: Converter smelting, LF refining, continuous casting, billet heating furnace heating, round steel rolling, heat treatment; among them: Combined blowing converter smelting ensures that the smelting materials are dry to avoid water vapor entering the steel to produce white spots; requirements [P] < 0.012%, [S] < 0.030%; nitrogen and argon blowing at the bottom of the converter ensures that the carbon is hit once and avoids post-blowing, and the end point carbon is controlled ≤ 0.10%, reducing the oxidation of molten steel and reducing decarburization; the end point [P] ≤ 0.020%; slag blocking during steel tapping, and argon blowing throughout the steel tapping process; During the refining of white slag, the molten steel must not be exposed; the calcium wire is used to deform the inclusions to avoid nozzle nodules; no slag is added after the calcium wire is fed to purify the molten steel, and the soft blowing time is ≥10min to ensure that the inclusions fully float; ferrovanadium is added in the later stage of refining; During continuous casting, the molten steel outside the long nozzle cannot be exposed to prevent secondary oxidation of the molten steel; ensure that the crystallizer is centered, use weak cooling for secondary cooling, control the cooling water distribution in the secondary cooling zone to 0.35-0.65L / kg, and keep the casting speed constant; use electromagnetic stirring to improve the surface quality of the ingot; The billet heating temperature is 1080~1120℃, the allowable temperature difference is ≤50℃, the total heating time is controlled to be 2h, the rolling temperature is 1030~1050℃, prevent overheating, overburning and decarburization, and heat up slowly to ensure uniform billet heating temperature and reduce temperature difference; The heat treatment system is 830-880℃ normalizing and 500-550℃ tempering; The mass percentage of the chemical composition of the hot-rolled ribbed steel bar includes: C 0.30%-0.40%, Si 0.60%-0.70%, Mn 1.50%-1.70%, P≤0.025%, S≤0.025%, V 0.15-0.25%, and the rest is Fe and inevitable trace impurities, with a total mass fraction of 100%.

2. The method for producing the 800MPa grade hot-rolled ribbed steel bar for high-strength anchor rod according to claim 1, characterized in that: Pay attention to the condition of the rollers, steel turning machines, guide plates, roller tables and cover plates, and ensure that they are smooth and have no sharp edges to avoid scratches and bumps on the surface of the rolled product. The specification of the rolled product is φ20mm.

3. The method for producing the 800MPa grade hot-rolled ribbed steel bar for high-strength anchor rod according to claim 1, characterized in that: The mass percentage of the chemical components of the hot-rolled ribbed steel bar includes: C 0.35%, Si 0.65%, Mn 1.55%, P 0.015%, S 0.005%, V 0.20%, and the rest is Fe and inevitable trace impurities, with a total mass fraction of 100%.

4. The method for producing the 800MPa grade hot-rolled ribbed steel bar for high-strength anchor rod according to claim 1, characterized in that: The mass percentage of the chemical components of the hot-rolled ribbed steel bar includes: C 0.34%, Si 0.66%, Mn 1.53%, P 0.014%, S 0.006%, V 0.19%, and the rest is Fe and inevitable trace impurities, with a total mass fraction of 100%.

5. The method for producing the 800MPa grade hot-rolled ribbed steel bar for high-strength anchor rod according to claim 1, characterized in that: The mass percentage of the chemical components of the hot-rolled ribbed steel bar includes: C 0.36%, Si 0.63%, Mn 1.58%, P 0.016%, S 0.004%, V 0.22%, and the rest is Fe and inevitable trace impurities, with a total mass fraction of 100%.

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