High-toughness 800mpa-grade photovoltaic support steel and method for manufacturing the same

Abstract

The application provides a high-toughness 800MPa-grade photovoltaic support steel and a preparation method thereof. In the preparation process of the high-toughness 800MPa-grade photovoltaic support steel, the specific process parameters of heating, hot rolling, cooling and coiling and the like are selected, so that the plasticity of the steel is improved, the deformation resistance is reduced, the internal organization and performance of the billet are improved, and the product quality is improved. The content of each element is controlled in a suitable range, so that the obtained steel material not only has good toughness, can adapt to the steel demand in a low-temperature environment, has excellent corrosion resistance, has a long service life, and low alloy cost is conducive to mass market application.

Description

Technical Field

[0001] This invention relates to the field of hot-rolled steel strip production technology, and in particular to a high-toughness 800MPa grade photovoltaic support steel and its preparation method. Background Technology

[0002] Accelerating the pace of carbon emission reduction is conducive to guiding green technology innovation and enhancing the global competitiveness of industries and the economy. To continuously promote industrial and energy structure adjustments and vigorously develop renewable energy, an increasing number of large-scale wind and solar power base projects are being planned and constructed in desert, Gobi, and other arid regions, leading to a continuous increase in the amount of steel used in solar photovoltaic systems.

[0003] The steel used in photovoltaic (PV) mounting systems not only needs good weather resistance but also toughness to withstand low-temperature environments. Traditional galvanized or magnesium-aluminum-zinc coated PV mounting steel involves long production processes, high energy consumption, and severe environmental pollution. Using uncoated high-strength weather-resistant steel as an alternative can reduce production processes, energy consumption, and pollution emissions. Therefore, the development of uncoated high-strength weather-resistant steel is of great significance. Some technologies for high-weather-resistant steel in PV mounting systems employ Nb-Ti alloying to improve strength and the addition of weather-resistant elements such as Cu, Cr, and Ni to achieve weather resistance. However, the high content of precious metals Ni (0.30%) and Nb (0.025%) results in high costs, hindering large-scale production.

[0004] In summary, there is an urgent need for a high-toughness 800MPa grade photovoltaic support steel and its preparation method to solve the problems existing in related technologies. Summary of the Invention

[0005] The main objective of this invention is to provide a high-toughness 800MPa grade photovoltaic support steel and its preparation method, so as to solve the technical problems of high cost, poor weather resistance and poor toughness of photovoltaic support steel in related technologies.

[0006] To achieve the above objectives, the present invention provides a high-toughness 800MPa grade photovoltaic support steel, the chemical composition of which, by weight percentage, includes: C: ≤0.08%, Si: 0.20%~0.40%, Mn: 0.50%~0.60%, P: ≤0.02%, S: ≤0.01%, Cu: 0.25%~0.30%, Cr: 2.5%~3.0%, Ti: 0.10%~0.15%, Als: 0.02%~0.05%, N: ≤0.0060%, with the remainder being Fe and unavoidable impurities.

[0007] Preferably, by weight percentage, it further comprises: C: ≤0.08%, Si: 0.20%~0.40%, Mn: 0.50%~0.60%, P: ≤0.02%, S: ≤0.01%, Cu: 0.25%~0.28%, Cr: 2.5%~2.8%, Ti: 0.10%~0.13%, Als: 0.02%~0.05%, N: ≤0.0060%, with the remainder being Fe and unavoidable impurities.

[0008] In this application, the above-mentioned elements have a synergistic effect. By controlling the content of each element within this range, the resulting steel not only has good toughness and can meet the steel requirements in low-temperature environments, but also greatly improves the atmospheric corrosion resistance of steel materials and has a long service life. In addition, this application does not contain Nb and Ni, resulting in lower costs.

[0009] The present invention also provides a method for preparing the above-mentioned high-toughness 800MPa grade photovoltaic support steel, comprising heating, hot rolling, cooling and coiling the steel billet in sequence; the chemical composition of the steel billet is the same as that of the above-mentioned high-toughness 800MPa grade photovoltaic support steel.

[0010] Preferably, the billet heating temperature is 1220℃~1240℃.

[0011] Preferably, the hot rolling step is finish rolling.

[0012] Preferably, the initial rolling temperature of the finishing mill is 970℃~1060℃, and the final rolling temperature of the finishing mill is 860℃~900℃.

[0013] Preferably, the cooling step includes an ultra-fast cooling step and a pre-cooling step; the cooling rate of the ultra-fast cooling step is 80℃ / S~120℃ / S, and the cooling time is 1S~2S; the cooling rate of the pre-cooling step is 20℃ / S~40℃ / S, and the cooling time is 1S~3S.

[0014] Preferably, in the winding step, the winding temperature is 580℃~610℃ and the thickness is 1.5mm~6.0mm.

[0015] This application improves the plasticity and toughness of steel, reduces deformation resistance, and improves the internal structure and properties of steel billets by selecting specific process parameters for steps such as heating, hot rolling, cooling, and coiling, thereby improving product quality. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0018] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0019] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0020] This invention provides a high-toughness 800MPa grade photovoltaic support steel, the chemical composition of which, by weight percentage, includes: C: ≤0.08%, Si: 0.20%~0.40%, Mn: 0.50%~0.60%, P: ≤0.02%, S: ≤0.01%, Cu: 0.25%~0.30%, Cr: 2.5%~3.0%, Ti: 0.10%~0.15%, Als: 0.02%~0.05%, N: ≤0.0060%, with the remainder being Fe and unavoidable impurities.

[0021] The principles behind the addition of each chemical element in this invention are as follows:

[0022] Carbon (C): C is an effective and economical element for improving the strength of steel. However, excessive C content will result in a brittle microstructure, reducing the low-temperature impact toughness of the steel plate, and deteriorating its weldability and corrosion resistance. Appropriate amounts of C can combine with Ti to form stable nanoscale precipitates, TiC. These TiC nanoscale precipitates produce strong precipitation strengthening and grain refinement effects, significantly improving the strength of the steel plate. To achieve a tensile strength of over 800 MPa and considering processing performance, weldability, and corrosion resistance, this application controls the C content to ≤0.08%.

[0023] Silicon (Si): Si is dissolved in steel, which can improve the strength of the steel plate and reduce the corrosion rate of the steel. However, excessive Si content will deteriorate the welding performance and reduce the toughness of the material. Therefore, this application controls the Si content to 0.20%~0.40%.

[0024] Manganese (Mn): Mn has a strong solid solution strengthening effect and a fine grain effect. It can improve toughness while increasing strength. However, excessive Mn content can easily lead to core component segregation and affect processing performance. Therefore, in order to make the steel plate have good strength and toughness while avoiding core component segregation, the Mn content in the embodiments of this application is controlled at 0.5%~0.6%.

[0025] Copper (Cu): Cu is a highly effective element for improving the corrosion resistance of steel. Cu can form a dense amorphous oxide protective layer on the surface of steel, thereby improving the corrosion resistance of steel. However, Cu has a low melting point and tends to accumulate at grain boundaries during heating. If the Cu content is too high, copper embrittlement will occur, leading to crack defects in the steel plate. Therefore, in the embodiments of this application, the Cu content is controlled at 0.25%~0.30%.

[0026] Chromium (Cr): Cr is a strong carbide-forming element that can reduce the activity of carbon in steel, improve the oxidation resistance of steel, and form a dense passivation film on the surface of steel, thereby improving the corrosion resistance of steel. However, excessively high Cr content will lead to excessively high steel plate costs. Therefore, in the embodiments of this application, the Cr content is controlled at 2.5%~3.0%.

[0027] Titanium (Ti): Ti reacts with N at high temperatures to form TiN. During the austenitization of the slab, TiN inhibits austenite grain growth. During hot rolling, Ti reacts with C at lower temperatures to form nanoscale TiC. These fine TiC particles exhibit significant precipitation strengthening and grain refinement, which is beneficial for improving the strength and low-temperature impact resistance of the steel plate. However, when the Ti content is too high, on the one hand, coarse, square TiN precipitates will form. When the steel plate is under stress, the stress will concentrate near the TiN particles, becoming a nucleation and growth source for microcracks, reducing the fatigue performance of the steel plate. On the other hand, due to the small solid solubility product of TiC, Ti is difficult to dissolve during the heating process of the continuously cast steel billet, thus failing to play its corresponding role. Therefore, this application controls the Ti element content to 0.10%–0.15%.

[0028] Aluminum (Al): In steelmaking, Al acts as a deoxidizer. At high temperatures, Al forms fine AlN precipitates, which inhibit austenite grain growth during the austenitization process of the steel billet, thus refining the grain size. However, excessive Al content leads to the formation of larger Al oxides, reducing the low-temperature impact resistance of the steel plate. Therefore, this application controls the Al content to 0.02%–0.05%.

[0029] Phosphorus, sulfur, and nitrogen: P, S, and N are harmful impurity elements in steel, which can significantly reduce the ductility, toughness, and weldability of steel. Therefore, the content of the above impurity elements should be reduced as much as possible. Therefore, this application controls the content of the three elements of phosphorus, sulfur, and nitrogen to P: ≤0.02%, S: ≤0.01%, and N: ≤0.0060%.

[0030] In this application, the selection of the contents of the above-mentioned elements, including Mn, Als and Ti, has a synergistic effect. By controlling them within this range, the grain refinement strengthening effect of each element is stronger, which is beneficial to improving the low-temperature impact performance of the steel plate, so that the steel has better toughness and can meet the steel requirements in low-temperature environments.

[0031] The aforementioned elements, including Cu and Cr, exhibit a synergistic effect when their contents are selected within a certain range. By controlling these elements within this range, the oxides of these two elements can form a dense, micron-sized oxide layer with good adhesion to the base metal between the steel rust layer and the substrate. The presence of this dense oxide film prevents atmospheric oxygen and water from penetrating into the steel substrate, slows down the progression of rust into the steel material, and thus greatly improves the steel material's resistance to atmospheric corrosion.

[0032] In some embodiments, the composition further comprises, by weight percentage: C: ≤0.08%, Si: 0.20%~0.40%, Mn: 0.50%~0.60%, P: ≤0.02%, S: ≤0.01%, Cu: 0.25%~0.28%, Cr: 2.5%~2.8%, Ti: 0.10%~0.13%, Als: 0.02%~0.05%, N: ≤0.0060%, with the remainder being Fe and unavoidable impurities.

[0033] The present invention also provides a method for preparing the above-mentioned high-toughness 800MPa grade photovoltaic support steel, comprising heating, hot rolling, cooling and coiling the steel billet in sequence; the chemical composition of the steel billet is the same as that of the above-mentioned high-toughness 800MPa grade photovoltaic support steel.

[0034] In some embodiments, the billet heating temperature is 1220℃~1240℃.

[0035] Heating steel billets to a suitable temperature improves their plasticity and reduces their resistance to deformation, making them easier to deform. This allows for greater reduction during subsequent rolling, reducing equipment failures caused by wear and impact, increasing mill productivity and operating rates, and reducing rolling energy consumption. Furthermore, it improves the internal structure and properties of the billet. Inhomogeneous structures and non-metallic inclusions are homogenized through diffusion during high-temperature heating.

[0036] In some embodiments, the hot rolling step is finish rolling.

[0037] Hot rolling improves the plasticity of metallic materials. Specifically, the grains of the metal become more active due to the heat, and grain boundary movement becomes easier. This enhances the plasticity of the metal, making it easier to perform plastic deformation. Through hot rolling, metallic materials can be rolled into various shapes, such as plates, pipes, and profiles.

[0038] Secondly, hot rolling improves the mechanical properties of metallic materials: During hot rolling, the metallic material undergoes plastic deformation, resulting in refined and homogenized grains. These fine grains have a significant impact on the material's strength and toughness. Fine grains can increase the material's strength, while uniformly distributed grains can improve its toughness. Therefore, hot-rolled metallic materials often exhibit better mechanical properties.

[0039] Furthermore, it improves the surface gloss of metallic materials: During the hot rolling process, the metallic materials are subjected to external forces, making their surface arrangement smoother, thereby improving their surface gloss.

[0040] Finally, reducing the surface strength of metal materials: During hot rolling, the metal material is subjected to external forces, which greatly reduces the surface strength of the material, thereby increasing the plasticity of the material, reducing the amount of processing and time, and lowering the processing cost.

[0041] In some embodiments, the initial finishing rolling temperature is 970℃~1060℃, and the final finishing rolling temperature is 860℃~900℃.

[0042] In some embodiments, the cooling step includes an ultra-fast cooling step and a pre-cooling step; the cooling rate of the ultra-fast cooling step is 80℃ / S~120℃ / S, and the cooling time is 1S~2S; the cooling rate of the pre-cooling step is 20℃ / S~40℃ / S, and the cooling time is 1S~3S.

[0043] By selecting appropriate ultra-fast cooling steps and process parameters in the pre-cooling steps, the steel can be cooled in a short time, refining the grains and significantly improving the strength and toughness of the steel. This results in the steel provided in this application having good low-temperature impact performance, making it suitable for photovoltaic support construction in low-temperature environments.

[0044] In addition, the ultra-fast cooling step and the pre-cooling step can reduce the degree of oxidation on the steel surface and generate a thin and dense oxide layer on the steel surface, thereby improving the surface quality of the steel strip.

[0045] In some embodiments, during the winding step, the winding temperature is 580℃~610℃ and the thickness is 1.5mm~6.0mm.

[0046] During the coiling process, different temperatures affect the microstructure of the steel. Generally, at high temperatures, the grain size of the steel is larger, and the grain boundaries are clear after cooling, but the hardness is lower. At low temperatures, the grain size is smaller, and the grain boundaries form an irregular structure after cooling, resulting in increased hardness. Therefore, in this application, the coiling temperature is set to 580℃~610℃.

[0047] High-strength steel for photovoltaic brackets offers greater safety and, by replacing low-strength materials, enables weight reduction, decreases material usage, and lowers material costs, transportation, and installation costs. Therefore, considering the steel requirements for photovoltaic brackets and the operating environment, this application sets the thickness to 1.5mm~6.0mm.

[0048] Example

[0049] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0050] Example 1:

[0051] A method for preparing high-toughness 800MPa grade photovoltaic bracket steel includes heating, hot rolling, cooling and coiling a steel billet sequentially to obtain high-toughness 800MPa grade photovoltaic bracket steel. The chemical composition of the high-toughness 800MPa grade photovoltaic bracket steel, by weight percentage, includes: C: 0.05%, Si: 0.20%, Mn: 0.53%, P: 0.017%, S: 0.0020%, Cu: 0.25%, Cr: 2.6%, Ti: 0.11%, Als: 0.025%, N: 0.0047%, with the remainder being Fe and unavoidable impurities.

[0052] In this embodiment, the billet heating temperature is 1220℃~1240℃.

[0053] In this embodiment, the hot rolling step is a finishing rolling; the starting temperature of the finishing rolling is 1020℃, and the finishing rolling temperature is 870℃; the cooling step includes an ultra-fast cooling step and a front-stage cooling step; the cooling rate of the ultra-fast cooling step is 100℃ / s, and the cooling time is 2s; the cooling rate of the front-stage cooling step is 35℃ / s, and the cooling time is 2s; in the coiling step, the coiling temperature is 600℃, and the thickness is 4.0mm.

[0054] The 800MPa grade photovoltaic support steel produced in this embodiment has a weathering resistance index I=

[0055] 26.01Cu + 3.88Ni + 1.2Cr + 1.49Si + 17.28P - 7.29CuNi - 9.1NiP - 33.39CuCu = 8.09 (Without adding Ni, the Ni value is 0 in the formula calculation)

[0056] Example 2: The difference from Example 1 is that the chemical composition of the high-toughness 800MPa grade photovoltaic bracket steel, by weight percentage, includes: C: 0.055%, Si: 0.20%, Mn: 0.50%, P: 0.015%, S: 0.0027%, Cu: 0.26%, Cr: 2.51%, Ti: 0.10%, Als: 0.025%, N: 0.0039%, with the remainder being Fe and unavoidable impurities.

[0057] Example 3: The difference from Example 1 is that the chemical composition of the high-toughness 800MPa grade photovoltaic bracket steel, by weight percentage, includes: C: 0.06%, Si: 0.30%, Mn: 0.60%, P: 0.015%, S: 0.0025%, Cu: 0.25%, Cr: 2.8%, Ti: 0.15%, Als: 0.025%, N: 0.0040%, with the remainder being Fe and unavoidable impurities.

[0058] Example 4: The difference from Example 1 is that the chemical composition of the high-toughness 800MPa grade photovoltaic bracket steel, by weight percentage, includes: C: 0.06%, Si: 0.40%, Mn: 0.60%, P: 0.015%, S: 0.0028%, Cu: 0.28%, Cr: 2.8%, Ti: 0.15%, Als: 0.025%, N: 0.0041%, with the remainder being Fe and unavoidable impurities.

[0059] Example 5: The difference from Example 1 is that the chemical composition of the high-toughness 800MPa grade photovoltaic bracket steel, by weight percentage, includes: C: 0.06%, Si: 0.2%, Mn: 0.50%, P: 0.015%, S: 0.0028%, Cu: 0.30%, Cr: 3.0%, Ti: 0.13%, Als: 0.025%, N: 0.0041%, with the remainder being Fe and unavoidable impurities.

[0060] Example 6: The difference from Example 1 is that the cooling rate of the ultra-fast cooling step is 80℃ / S and the cooling time is 2S, while the cooling rate of the pre-cooling step is 20℃ / S and the cooling time is 3S.

[0061] Example 7: The difference from Example 1 is that the cooling rate of the ultra-fast cooling step is 120℃ / s and the cooling time is 1s, while the cooling rate of the pre-cooling step is 40℃ / s and the cooling time is 2s.

[0062] Comparative Example 1: The difference from Example 1 is that the chemical composition of the high-toughness 800MPa grade photovoltaic bracket steel, by weight percentage, includes: C: 0.06%, Si: 0.30%, Mn: 1.0%, P: 0.016%, S: 0.0025%, Cu: 0.28%, Cr: 2.6%, Ti: 0.20%, Als: 0.025%, N: 0.0039%, with the remainder being Fe and unavoidable impurities.

[0063] Comparative Example 2: The difference from Example 1 is that the chemical composition of the high-toughness 800MPa grade photovoltaic bracket steel, by weight percentage, includes: C: 0.06%, Si: 0.30%, Mn: 0.40%, P: 0.016%, S: 0.0029%, Cu: 0.25%, Cr: 2.6%, Ti: 0.05%, Als: 0.025%, N: 0.0042%, with the remainder being Fe and unavoidable impurities.

[0064] Comparative Example 3: The difference from Example 1 is that the chemical composition of the high-toughness 800MPa grade photovoltaic bracket steel, by weight percentage, includes: C: 0.06%, Si: 0.15%, Mn: 0.50%, P: 0.016%, S: 0.0027%, Cu: 0.20%, Cr: 2.0%, Ti: 0.2%, Als: 0.025%, N: 0.0039%, with the remainder being Fe and unavoidable impurities.

[0065] Comparative Example 4: The difference from Example 1 is that the chemical composition of the high-toughness 800MPa grade photovoltaic bracket steel, by weight percentage, includes: C: 0.06%, Si: 0.2%, Mn: 0.60%, P: 0.017%, S: 0.0026%, Cu: 0.40%, Cr: 3.5%, Ti: 0.05%, Als: 0.02%, N: 0.0040%, with the remainder being Fe and unavoidable impurities.

[0066] Comparative Example 5: The difference from Example 1 is that the cooling step does not use ultra-fast cooling, the cooling rate of the first cooling step is 40℃ / S, and the cooling time is 6S.

[0067] Comparative Example 6: The difference from Example 1 is that the cooling step is a post-cooling process with a cooling rate of 40°C / s and a cooling time of 6s.

[0068] Comparative Example 7: The difference from Example 1 is that the cooling rate of the ultra-fast cooling step is 60°C / s and the cooling time is 3s, while the cooling rate of the pre-cooling step is 50°C / s and the cooling time is 1s.

[0069] Comparative Example 8: The difference from Example 1 is that the cooling rate of the ultra-fast cooling step is 130°C / s and the cooling time is 1s, while the cooling rate of the pre-cooling step is 10°C / s and the cooling time is 4s.

[0070] The steels obtained in Examples 1-7 and Comparative Examples 1-8 were subjected to performance testing. The performance tests included tensile tests according to GB / T 228.1-2010 and impact tests according to GB / T 229-2007. The test results are shown in Table 1.

[0071] Table 1. Performance test results of the steels obtained in Examples 1-7 and Comparative Examples 1-8

[0072]

[0073]

[0074] As shown in Table 1, compared with Comparative Examples 1-2, the selection of appropriate Mn and Ti contents in Examples 1-3 has a synergistic effect, which is beneficial to improving the strength and low-temperature impact performance of the steel plate, while also having a higher elongation. This results in the steel having better toughness and plasticity, which can meet the steel requirements in low-temperature environments and the strict bending / roller forming requirements. However, if the contents are below the range, the yield strength and tensile strength of the steel will decrease significantly, while if the contents are above the range, the elongation of the steel will decrease significantly, which cannot meet the processing and forming requirements of the steel for photovoltaic brackets.

[0075] Compared with Comparative Examples 3-4, Examples 1, 4, and 5 show that selecting appropriate Cu and Cr contents has a synergistic effect, which can improve the atmospheric corrosion resistance of steel materials and maintain a certain strength. However, when the contents are below a certain range, the weather resistance of the steel decreases. When the contents are above this range, for example, excessive Cu content will cause copper embrittlement, leading to cracks in the steel plate. Excessive Cr content will lead to excessively high steel plate costs. In Comparative Example 4, the Ti content was too low, resulting in a significant decrease in the strength of the steel.

[0076] Compared with Comparative Examples 5-6, Example 1 shows that the combination of the ultra-fast cooling step and the pre-cooling step can not only improve the yield strength and tensile strength of steel, but also improve the low-temperature impact performance of steel.

[0077] Compared with Comparative Examples 7-8, Examples 1, 6, and 7 show that selecting an appropriate cooling rate can improve the low-temperature impact energy of steel.

[0078] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing high-toughness 800MPa grade photovoltaic support steel, characterized in that, include: The steel billet is heated, hot-rolled, cooled, and coiled in sequence. The chemical composition of the steel billet, by weight percentage, includes: C: ≤0.08%, Si: 0.20%~0.40%, Mn: 0.50%~0.60%, P: ≤0.02%, S: ≤0.01%, Cu: 0.25%~0.30%, Cr: 2.5%~3.0%, Ti: 0.10%~0.15%, Als: 0.02%~0.05%, N: ≤0.0060%, with the remainder being Fe and unavoidable impurities; The steel billet is heated at a temperature of 1220℃~1240℃; The cooling process includes an ultra-fast cooling process and a pre-cooling process; the cooling rate of the ultra-fast cooling process is 80℃ / s to 120℃ / s, and the cooling rate of the pre-cooling process is 20℃ / s to 40℃ / s. The hot rolling step is a finishing rolling; The initial rolling temperature for finishing is 970℃~1060℃, and the final rolling temperature for finishing is 860℃~900℃. The cooling time of the ultra-fast cooling step is 1 to 2 seconds, and the cooling time of the pre-cooling step is 1 to 3 seconds. In the winding step, the winding temperature is 580℃~610℃ and the thickness is 1.5mm~6.0mm.

2. A high-toughness 800MPa grade photovoltaic support steel, characterized in that, It was prepared by the method described in claim 1.

3. The high-toughness 800MPa grade photovoltaic support steel according to claim 2, characterized in that, Its chemical composition by weight percentage includes: C: ≤0.08%, Si: 0.20%~0.40%, Mn: 0.50%~0.60%, P: ≤0.02%, S: ≤0.01%, Cu: 0.25%~0.28%, Cr: 2.5%~2.8%, Ti: 0.10%~0.13%, Als: 0.02%~0.05%, N: ≤0.0060%, with the remainder being Fe and unavoidable impurities.

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