Hot rolled steel strip for high-strength and high-prestress anchor rod body and preparation method and application of hot rolled steel strip

Abstract

The invention provides a hot rolled steel strip for a high-strength and high-prestress anchor rod body and a preparation method and application of the hot rolled steel strip. The hot rolled steel strip is prepared from the following components in percentage by weight: 0.16 percent to 0.20 percent of C, 0.15 percent to 0.25 percent of Si, 0.75 percent to 0.95 percent of Mn, less than or equal to 0.010 percent of P, less than or equal to 0.007 percent of S, 0.01 percent to 0.13 percent of N, 0.15 percent to 0.25 percent of Mo, 0.020 percent to 0.060 percent of Nb, 0.020 percent to 0.035 percent of V, 1.00 percent to 1.20 percent of Cr, 0.20 percent to 0.30 percent of Cu, 0.002 percent to 0.003 percent of B and the balance of Fe and impurities. The hot rolled steel strip for the high-strength and high-prestress anchor rod body is obtained by adopting a component design thought of medium carbon + Mo-Nb-V alloying and combining a controlled rolling and controlled cooling process.

Description

Technical Field

[0001] The present invention belongs to the technical field of hot-rolled strip steel, and in particular relates to a hot-rolled steel strip for a high-strength and high-prestressed anchor rod body, and a preparation method and application thereof. Background Art

[0002] With the rapid development of my country's economy, large-span tunnels with spans exceeding 14 meters have become commonplace in highway construction. Anchor bolts primarily serve as support and reinforcement in tunnels, often acting as both surrounding rock and supporting structures, and are important load-bearing devices. As tunnel spans increase, the load-bearing capacity requirements for anchor bolts are also increasing. While existing anchor steel products such as MG500 and SMG600 offer improved strength compared to MG355, their strength and deformation capacity still cannot fully meet the requirements of large-span and ultra-large-span tunnels.

[0003] To address these issues, CN119464898A discloses a 500MPa-grade hot-rolled steel for hollow anchor welded pipes with high ductility, as well as its preparation method and application. This method enhances material strength by controlling the solid solution strengthening of C, Si, and Mn, while adding a certain amount of Cr to ensure the hardenability of the anchor rod body. The resulting hot-rolled steel exhibits high strength and ductility. However, the maximum elongation at force after fabrication into the anchor rod body remains relatively low, failing to meet the requirements for use in larger-span tunnels.

[0004] Therefore, there is an urgent need to develop a high prestressed anchor steel so that its strength and deformation capacity can meet the use requirements of large-span tunnels. Summary of the Invention

[0005] In view of this, the present invention aims to provide a hot-rolled steel strip for high-strength and high-prestressed anchor rod body, and its preparation method and application. The hot-rolled steel strip has a maximum elongation of 15-18% and has excellent mechanical properties and corrosion resistance.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a hot-rolled steel strip for a high-strength and high-prestressed anchor rod body, which comprises the following components, calculated by weight percentage:

[0008] C 0.16%~0.20%, Si 0.15%~0.25%, Mn 0.75%~0.95%, P≤0.010%, S≤0.007%, N 0.01%~0.13%, Mo 0.15%~0.25%, Nb 0.020%~0.060%, V0.020%~0.035%, Cr 1.00%~1.20%, Cu 0.20%~0.30%, B 0.002%~0.003%, and the rest are Fe and impurities.

[0009] Preferably, the hot-rolled steel strip is composed of the following components in terms of element weight percentage:

[0010] C 0.16%~0.18%, Si 0.15%~0.25%, Mn 0.80%~0.95%, P≤0.010%, S≤0.007%, N 0.01%~0.13%, Mo 0.15%~0.20%, Nb 0.020%~0.050%, V0.020%~0.032%, Cr 1.00%~1.18%, Cu 0.20%~0.27%, B 0.002%~0.003%, and the rest are Fe and impurities.

[0011] Preferably, the metallographic structure of the hot-rolled steel strip is ferrite+pearlite+granular bainite.

[0012] Preferably, the yield strength of the hot-rolled steel strip is ≥700 MPa, the tensile strength is ≥850 MPa, and the maximum elongation is 15% to 18%.

[0013] In a second aspect, the present invention provides a method for preparing the hot-rolled steel strip, comprising the following steps:

[0014] After the molten iron is desulfurized, converter, LF refining, continuous casting, hot rolling, laminar cooling and coiling are carried out in sequence to obtain the hot-rolled steel strip.

[0015] Preferably, after desulfurization, the molten iron has a sulfur content of ≤0.007% when entering the converter, and the tapping temperature of the converter is 1640°C to 1650°C.

[0016] Preferably, the outlet temperature of the LF refining is 1580±5°C.

[0017] Preferably, the LF is treated with calcium after refining, argon is blown throughout the process, and the treatment time is ≥8 minutes.

[0018] Preferably, the continuous casting adopts constant speed casting, and the casting speed is 0.8-1m / min.

[0019] Preferably, the hot rolling includes billet heating, rough rolling and finish rolling.

[0020] Preferably, the temperature of heating the steel billet is 1230-1240°C.

[0021] Preferably, the starting rolling temperature of the rough rolling is ≥1150°C, the finishing rolling temperature is ≥1050°C, and the rough rolling includes 6 passes, wherein the total deformation of the 1st to 2nd passes is ≥15%, and the total deformation of the 3rd to 6th passes is ≥20%.

[0022] Preferably, after the rough rolling is completed, the thickness of the intermediate billet obtained is 40±1 mm.

[0023] Preferably, the final rolling temperature of the finish rolling is 870±10°C.

[0024] Preferably, the laminar cooling adopts a front-stage cooling method, and the cooling rate of the laminar cooling is 25-40°C / s.

[0025] In a third aspect, the present invention provides an application of the hot-rolled steel strip in tunnel support or reinforcement.

[0026] Preferably, the tunnel comprises a road tunnel or a railway tunnel, and the span of the tunnel is 14 to 18 meters.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention provides a hot-rolled steel strip for a high-strength, high-prestress anchor rod body. The steel strip comprises, by element weight percentage, the following: C 0.16% to 0.20%, Si 0.15% to 0.25%, Mn 0.75% to 0.95%, P ≤ 0.010%, S ≤ 0.007%, N 0.01% to 0.13%, Mo 0.15% to 0.25%, Nb 0.020% to 0.060%, V 0.020% to 0.035%, Cr 1.00% to 1.20%, Cu 0.20% to 0.30%, B 0.002% to 0.003%, with the remainder being Fe and impurities. The present invention utilizes a medium-carbon + Mo-Nb-V alloying design approach. By controlling the C and Si contents, the steel's strength is ensured, while reducing weld crack sensitivity. Mo combined with small amounts of Nb and V enhances its strength and toughness. At the same time, the carbonitrides precipitated from Nb and V are utilized to exert their effects of grain refinement and precipitation strengthening, ensuring the toughness of the anchor steel. The present invention also adds appropriate amounts of Cr and Cu elements, which not only improve the hardenability of the steel but also impart a certain degree of corrosion resistance to the anchor steel, allowing it to be used in humid environments, and has a wider range of applications than existing anchor steels.

[0029] According to tests, the yield strength of the hot-rolled steel strip is ≥700 MPa, the tensile strength is ≥850 MPa, and the maximum elongation is 15% to 18%.

[0030] Therefore, the hot-rolled steel strip provided by the present invention is suitable for making steel anchor rods for highway (or railway) tunnel support, especially for making high-strength and high-prestressed anchor rods for large-span tunnels. At the same time, it also has corrosion resistance and can meet the use requirements of humid environments such as coastal areas, and has broad market application prospects. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] To address the problems of insufficient strength and low effective elongation of anchor steel in long-span tunnels, the present invention provides a hot-rolled steel strip for a high-strength and high-prestressed anchor rod body, which comprises the following components, calculated by weight percentage:

[0033] C 0.16%~0.20%, Si 0.15%~0.25%, Mn 0.750.020%~0.060%%~0.95%, P≤0.010%, S≤0.007%, N 0.01%~0.13%, Mo 0.15%~0.25%, Nb 0.020%~0.060%, V 0.020%~0.035%, Cr 1.00%~1.20%, Cu 0.20%~0.30%, B 0.002%~0.003%, and the rest are Fe and unavoidable impurities. Controlling the C and Si contents ensures steel strength and reduces weld crack sensitivity. An appropriate amount of Cr improves the steel's hardenability, while Mo, combined with small amounts of Nb and V, significantly enhances strength and toughness. The microalloying of Nb and V facilitates the precipitation of fine carbonitrides, ensuring the anchor steel's toughness through grain refinement and precipitation strengthening. Furthermore, the presence of Cr and Cu imparts excellent corrosion resistance to the steel anchor, extending its service life in humid environments.

[0034] In the present invention, the main functions of the above elements are as follows:

[0035] C: C can significantly improve the strength of steel, but an increase in its content is detrimental to plasticity and toughness. To ensure excellent strength and toughness, the C content in the present invention is preferably controlled to 0.16% to 0.20%, more preferably 0.16% to 0.18%.

[0036] Si: Si can improve the strength of steel through solid solution strengthening, but too high a content can reduce the plasticity and toughness of the steel and make descaling during rolling difficult. Therefore, in the present invention, the Si content is preferably controlled within a range of 0.15% to 0.25%.

[0037] Mn: Mn significantly expands the austenite phase in steel, lowers the phase transition temperature, refines the phase transition structure, and alters the microstructure. However, excessive Mn content can easily cause segregation in the center of the steel, leading to cracking. Therefore, to ensure the mechanical properties of the material, the Mn content in this invention is preferably controlled within a range of 0.75% to 0.95%, more preferably 0.80% to 0.95%.

[0038] Mo: Mo forms stable compounds, reduces temper brittleness, and effectively improves the strength and hardness of steel. However, excessive Mo content can reduce toughness. The addition of Mo also improves the structure of corrosion product films, enhancing the steel's resistance to localized corrosion, such as pitting. Mo also increases the solubility of Nb and V, promoting precipitation strengthening. Therefore, the Mo content is designed to be within a range of 0.15% to 0.25%, with a more preferred range of 0.15% to 0.20%.

[0039] Nb: Nb is a strong nitrogen carbide-forming element. During the cooling process after rolling, it can form intermediate phases such as niobium carbonitride. These fine carbide particles can refine the microstructure, produce fine grain strengthening and precipitation strengthening, and significantly improve the strength of the steel plate. At the same time, the refinement of the microstructure is beneficial to improving the toughness of the steel plate. Therefore, adding an appropriate amount of Nb to the steel can help improve the strength. However, excessive Nb content increases production costs, so it is generally not recommended to add too much. The content is limited to 0.020% to 0.060%, and more preferably 0.002% to 0.005%.

[0040] V: V is also a strong carbonitride-forming element, precipitating during phase transformation. It provides solid solution strengthening and carbonitride precipitation strengthening in steel, and can increase tempering stability, thereby improving strength. When added in combination with Nb, it can both increase steel strength and improve toughness. Therefore, the V content is controlled within a range of 0.020% to 0.035%, more preferably 0.020% to 0.032%.

[0041] Cr and Cu: Cr improves the hardenability of steel, ensuring good weldability; Cu increases strength, compensating for the strength loss of low-Mn designs. However, excessive Cu content is detrimental to toughness and tends to aggregate and precipitate at austenite grain boundaries. Reaching a certain level can cause cracks during heating or hot rolling. Cr and Cu are corrosion-resistant alloying elements, and their combined addition can enhance the corrosion resistance of steel. While ensuring the strength and toughness of the steel, the present invention preferably controls the Cr content within a range of 1.00% to 1.20%, more preferably 1.00% to 1.18%, and the Cu content within a range of 0.20% to 0.30%, more preferably 0.20% to 0.27%. This ensures that the anchor rod body also possesses a certain degree of corrosion resistance.

[0042] B: A trace amount of B element can significantly improve the hardenability of steel, and the effect is more significant when combined with Cr element. However, its content should generally not exceed 0.0050%. In the present invention, the B content is preferably controlled at 0.0020-0.0030%.

[0043] N: Similar to the role of C, it can improve the strength of steel through interstitial solid solution. However, solid solution N has a great harm to the plasticity and toughness of steel. Therefore, the N content must be strictly controlled in the range of 0.010% to 0.013%.

[0044] P, S: Too high P and S content will significantly reduce the toughness, plasticity and brittleness of steel, deteriorating the performance of the steel. Therefore, in the present invention, the P content is ≤ 0.010%; the S content is ≤ 0.007%.

[0045] The present invention also provides a method for preparing the hot-rolled steel strip, comprising the following steps:

[0046] After the molten iron is desulfurized, converter, LF refining, continuous casting, hot rolling, laminar cooling and coiling are carried out in sequence to obtain the hot-rolled steel strip.

[0047] According to the present invention, molten iron is first desulfurized. The present invention has no special restrictions on the desulfurization of molten iron and can be carried out according to means familiar to those skilled in the art. Preferably, after desulfurization, converter refining requires S≤0.007% to avoid deterioration of steel performance.

[0048] In the present invention, after the molten iron is desulfurized, it enters the converter for smelting. The converter smelting can be carried out according to methods well known to those skilled in the art, without particular limitation. In some embodiments of the present invention, the tapping temperature of the converter is 1640°C to 1650°C.

[0049] In the present invention, after the converter smelting is completed, the LF refining is performed. The LF refining can be performed according to methods well known to those skilled in the art and is not particularly limited. In some embodiments of the present invention, the outlet temperature of the LF refining is 1580±5°C.

[0050] In the present invention, the LF is preferably treated with calcium after refining, with argon blowing throughout the process, and the treatment time is ≥8 minutes.

[0051] In the present invention, after the LF refining is completed, continuous casting is performed. The continuous casting can be performed using methods well known to those skilled in the art, without particular limitation. In some embodiments of the present invention, the continuous casting is performed using a constant casting speed of 0.8 to 1 m / min, preferably 0.9 m / min.

[0052] In the present invention, after the continuous casting is completed, hot rolling is performed. In the present invention, the hot rolling includes billet heating, rough rolling and finish rolling.

[0053] The temperature of heating the steel billet is 1230-1240° C., preferably 1230-1235° C. The present invention controls the temperature of heating the steel billet, which is beneficial to homogenizing the as-cast structure, avoiding component segregation, and dissolving the alloy elements.

[0054] The starting rolling temperature of the rough rolling is ≥1150° C., and the finishing rolling temperature is ≥1050° C. The present invention controls the starting rolling temperature and the finishing rolling temperature to ensure that the steel billet is in the austenite region and to avoid abnormal grain growth.

[0055] The rough rolling preferably includes 6 passes, wherein the total deformation of the first and second passes is ≥15% and the total deformation of the third to sixth passes is ≥20%. In this way, the austenite grains can be refined to prevent the formation of mixed crystal structure.

[0056] After the rough rolling, the thickness of the intermediate bar is preferably controlled to 40 ± 1 mm. If the intermediate bar is too thick, the rough rolling deformation may be insufficient, and if the finished product thickness is thin, the finishing rolling load may be too high. If the intermediate bar is too thin, the finishing rolling deformation may be insufficient. Therefore, the thickness of the intermediate bar is preferably controlled to 40 ± 1 mm in the present invention to ensure uniform finishing rolling deformation and reduce defects such as warping.

[0057] After rough rolling, finishing rolling is performed. In the present invention, the final rolling temperature for finishing rolling is 870±10°C. If the finishing temperature is too low, abnormal ferrite grain growth may occur on the surface of the strip, leading to uneven structure through the thickness and potentially causing uneven deformation during the forming process. Controlling the finishing temperature of finishing rolling within the above range facilitates refinement of austenite grains and prevents abnormal structure growth.

[0058] The present invention does not impose any particular limitation on the hot rolling process, and the process may be carried out according to methods well known to those skilled in the art, but the above-mentioned process parameters must be met.

[0059] In the present invention, after hot rolling, laminar cooling is performed. The laminar cooling adopts a front-stage cooling method, and the laminar cooling is preferably performed at a cooling rate of 25 to 40°C / s to the coiling temperature, preferably at a cooling rate of 30 to 40°C / s to the coiling temperature.

[0060] In the present invention, the coiling temperature is 590-620°C, preferably 600-610°C.

[0061] After testing, the finished steel strip prepared based on the above preparation method has a thickness of 3.0 mm, and the microstructure is ferrite + pearlite + a small amount of granular bainite (not exceeding 6%). A small amount of granular bainite is conducive to obtaining good elongation, yield strength Rel ≥ 700 MPa, tensile strength Rm ≥ 850 MPa, and maximum elongation is 15% to 18%.

[0062] Furthermore, in the present invention, the hot-rolled steel strip is made into a hollow anchor rod by straight seam welding, and the total elongation of the rod body under maximum force can reach 12-15%.

[0063] In summary, the present invention adopts the composition design concept of medium carbon + "Mo-Nb-V" alloying, and combines the controlled rolling and controlled cooling process to regulate the microstructure and grain size of the steel plate, so as to obtain a hot-rolled steel strip for high-strength and high-prestressed anchor rod body, and the hollow anchor rod further prepared has a higher maximum elongation.

[0064] Based on this, the present invention also provides an application of the above-mentioned hot-rolled steel strip or hollow anchor rod in tunnel support or reinforcement.

[0065] The tunnel includes a road tunnel or a railway tunnel, and the span of the tunnel is 14 to 18 meters.

[0066] In order to further illustrate the present invention, the following examples are given below to provide a detailed description.

[0067] Example 1

[0068] This embodiment provides a hot-rolled steel strip for a high-strength and high-prestressed anchor rod body. The steel strip is smelted according to the chemical composition shown in Table 1 and prepared through the following steps: molten iron desulfurization → converter → LF refining → continuous casting → hot rolling → laminar cooling → coiling. The specific process control parameters for each process are as follows (see Table 2):

[0069] 1) After desulfurization, the sulfur content of the hot metal entering the converter is 0.006%.

[0070] 2) Converter and LF refining process: converter tapping temperature is 1645°C; LF outlet temperature is 1578°C, calcium treatment is used after LF refining, argon is blown throughout the process, and the treatment time is 9 minutes.

[0071] 3) Continuous casting process: constant speed casting is adopted, and the casting speed is 0.9m / min.

[0072] 4) Hot rolling process: the billet heating temperature is 1230℃, the rough rolling start temperature is 1155℃, the final rolling temperature is 1051℃, a total of 6 passes, the total deformation of the 1st to 2nd passes is 17%, the total deformation of the 3rd to 6th passes is 33%, the intermediate billet thickness is 40.1mm; the finishing rolling temperature is 875℃.

[0073] 5) Laminar cooling process: adopt the front cooling method and cool to the coiling temperature at a cooling rate of 32℃ / s.

[0074] 6) Coiling process: Coiling temperature 615℃.

[0075] Example 2

[0076] This embodiment provides a hot-rolled steel strip for a highly corrosion-resistant anchor rod body, which is smelted according to the chemical composition in Table 1 and prepared through the steps of molten iron desulfurization → converter → LF refining → continuous casting → hot rolling → laminar cooling → coiling. Each process refers to Example 1, and the specific process control parameters are shown in Table 2.

[0077] Example 3

[0078] This embodiment provides a hot-rolled steel strip for a highly corrosion-resistant anchor rod body, which is smelted according to the chemical composition in Table 1 and prepared through the steps of molten iron desulfurization → converter → LF refining → continuous casting → hot rolling → laminar cooling → coiling. Each process refers to Example 1, and the specific process control parameters are shown in Table 2.

[0079] Comparative Example 1

[0080] This comparative example provides an anchor steel, the composition of which is as described in Table 1, and the preparation method is carried out according to patent CN202411644934.9.

[0081] Table 1

[0082]

[0083] Table 2

[0084]

[0085] Performance Testing

[0086] The present invention uses the products obtained in Examples 1 to 3 and Comparative Example 1 as samples to conduct mechanical property and microstructure tests.

[0087] Among them, the mechanical properties of the hot-rolled steel strip and the anchor rod body are tested in accordance with GB / T 228.1-2021 "Metallic materials, tensile tests, part 1: room temperature test methods";

[0088] The metallographic structure was observed using an optical microscope.

[0089] The test results are shown in Table 3:

[0090] Table 3

[0091]

[0092]

[0093] As shown in Table 3, the present invention adopts the design concept of medium carbon + "Mo-Nb-V" alloy, which can ensure the toughness of the anchor rod body. Compared with Comparative Example 1, the alloy composition design is significantly different and the mechanical properties are better.

[0094] The present invention uses the products obtained in Examples 1 to 3 and Comparative Example 1 as samples to conduct corrosion performance tests.

[0095] The corrosion rate test solution is 3.5% NaCl solution, the corrosion resistance test specimen size is 10mm×10mm×10mm, the test temperature is 25±2℃, the specimen immersion period is 40d, and the solution is changed every 5d. After the test, the corrosion resistance of the material is evaluated by the 40d corrosion rate of the specimen, and the calculation formula is: v=8.76×10 4 ×(W1-W2) / (S×T×D). Where v is the corrosion rate, mm / a; W1 is the mass of the sample before the test, g; W2 is the mass of the sample after the test, g; S is the sample area, cm 2 ; T is the test time, h; D is the density of the test material, kg / m 3 .

[0096] The test results are shown in Table 4.

[0097] Table 4

[0098] Group Corrosion rate mm / a Example 1 0.05632 Example 2 0.05578 Example 3 0.05702 Comparative Example 1 0.09721

[0099] As can be seen from Table 4, the prepared product also has certain corrosion resistance, can be used in a humid environment, and has a wider range of adaptability.

[0100] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A hot-rolled steel strip for high-strength and high-prestressed anchor rod body, characterized in that: Calculated by element weight percentage, it is composed of the following ingredients: C 0.16%~0.20%, Si 0.15%~0.25%, Mn 0.75%~0.95%, P≤0.010%, S≤0.007%, N 0.01%~0.13%, Mo 0.15%~0.25%, Nb 0.020%~0.060%, V0.020%~0.035%, Cr 1.00%~1.20%, Cu 0.20%~0.30%, B 0.002%~0.003%, and the rest are Fe and impurities.

2. The hot rolled steel strip according to claim 1, characterized in that The hot-rolled steel strip is composed of the following components in terms of element weight percentage: C 0.16%~0.18%, Si 0.15%~0.25%, Mn 0.80%~0.95%, P≤0.010%, S≤0.007%, N 0.01%~0.13%, Mo 0.15%~0.20%, Nb 0.020%~0.050%, V0.020%~0.032%, Cr 1.00%~1.18%, Cu 0.20%~0.27%, B 0.002%~0.003%, and the rest are Fe and impurities.

3. The hot rolled steel strip according to claim 1 or 2, characterized in that: The metallographic structure of the hot-rolled steel strip is ferrite+pearlite+granular bainite; The yield strength of the hot-rolled steel strip is ≥700 MPa, the tensile strength is ≥850 MPa, the total elongation is 20% to 25%, and the maximum elongation is 15% to 18%.

4. A method for preparing a hot-rolled steel strip according to any one of claims 1 to 3, characterized in that: The following steps are involved: After the molten iron is desulfurized, converter, LF refining, continuous casting, hot rolling, laminar cooling and coiling are carried out in sequence to obtain the hot-rolled steel strip.

5. The preparation method according to claim 4, characterized in that After the molten iron is desulfurized, S≤0.007% when entering the converter, and the tapping temperature of the converter is 1640°C to 1650°C.

6. The preparation method according to claim 4 or 5, characterized in that The outlet temperature of the LF refining is 1580±5°C; The LF is treated with calcium after refining, with argon blowing throughout the process, and the treatment time is ≥8 minutes.

7. The preparation method according to any one of claims 4 to 6, characterized in that The continuous casting adopts constant speed casting, and the casting speed is 0.8-1m / min.

8. The preparation method according to any one of claims 4 to 7, characterized in that The hot rolling includes billet heating, rough rolling and finish rolling; The temperature of heating the steel billet is 1230-1240°C; The starting rolling temperature of the rough rolling is ≥1150°C, the finishing rolling temperature is ≥1050°C, and the rough rolling includes 6 passes, wherein the total deformation of the 1st to 2nd passes is ≥15%, and the total deformation of the 3rd to 6th passes is ≥20%; After the rough rolling is completed, the thickness of the intermediate billet obtained is 40±1 mm; The final rolling temperature of the finishing rolling is 870±10°C.

9. The preparation method according to any one of claims 4 to 8, characterized in that The laminar cooling adopts a front-stage cooling method, and the cooling speed of the laminar cooling is 25-40°C / s.

10. Use of the hot-rolled steel strip for high-strength and high-prestressed anchor rod according to any one of claims 1 to 3 or the hot-rolled steel strip produced by the production method according to any one of claims 4 to 9 in tunnel support or reinforcement; The tunnel includes a road tunnel or a railway tunnel, and the span of the tunnel is 14 to 18 meters.

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