High-toughness and high-corrosion-resistance steel for photovoltaic support as well as preparation method and application of high-toughness and high-corrosion-resistance steel

Abstract

The invention relates to the technical field of steel and iron materials, in particular to high-toughness and high-corrosion-resistance steel for a photovoltaic support as well as a preparation method and application of the high-toughness and high-corrosion-resistance steel, and the high-toughness and high-corrosion-resistance steel comprises the following components in percentage by mass: 0.09%-0.15% of C, 0.55%-0.80% of Si, 0.8%-1.1% of Mn, 0.8%-1.2% of Cr, 0.03%-0.06% of Ti, 0.20%-0.60% of Al, 0.01%-0.03% of Nb, less than or equal to 0.006% of S, less than or equal to 0.035% of P and the balance of Fe and inevitable impurities. By adding Al, Ti, Cr and other elements, the strength and corrosion resistance of the steel are improved, finally, the yield strength of the steel is larger than or equal to 500 MPa, the tensile strength is larger than or equal to 600 MPa, the percentage elongation after fracture is larger than 20%, and the minimum corrosion rate is 0.05 g / m < 2 >. H (test standard GB / T10125-2021).

Description

Technical Field

[0001] This invention relates to the field of steel materials technology, and in particular to a high-strength, high-toughness, and high-corrosion-resistant steel for photovoltaic brackets, its preparation method, and its application. Background Technology

[0002] Driven by the global energy transition and the "dual carbon" goal, the photovoltaic industry has developed rapidly, leading to a surge in demand for steel for photovoltaic brackets (approximately 56 tons of steel are required for a 1MW photovoltaic power station). Large-scale photovoltaic power stations in harsh environments such as deserts and Gobi account for over 60% of the total. As a core structural component, photovoltaic brackets must meet three major requirements: high strength, high corrosion resistance, and low cost (design life ≥ 25 years, bracket cost accounts for 15%-20% of the total investment in the power station). However, existing materials struggle to balance these three aspects: hot-dip galvanized carbon structural steel (such as Q235 and Q355) is low in cost but has a strength ≤ 355MPa and a salt spray life of only 1000-1500 hours, requiring frequent maintenance; stainless steel (such as 304 and 316L) has excellent corrosion resistance but a strength ≤ 275MPa and contains the precious metal Ni, resulting in high costs and hindering large-scale application; aluminum alloys (such as 6061-T6) are lightweight but have a strength ≤ 310MPa, corrosion resistance depends on surface treatment, and recycling rates are low. Currently, the high-strength corrosion-resistant steels being developed in trials mostly rely on precious metals such as Ni and Mo, resulting in high costs. Excessive Cr content leads to low billet yield and insufficient toughness, posing safety hazards. Therefore, there is an urgent need to develop photovoltaic bracket steels that do not rely on precious metals but can achieve high yield strength, good toughness, low cost, and strong corrosion resistance, in order to overcome existing technological bottlenecks and meet the cost reduction and efficiency improvement needs of the photovoltaic industry. Summary of the Invention

[0003] The purpose of this invention is to provide a high-strength, high-toughness, and high-corrosion-resistant photovoltaic bracket steel, its preparation method, and its application. It does not rely on precious metals. By adding appropriate amounts of Cr, Ti, and Al, and optimizing the composition and process, it achieves photovoltaic bracket steel with high yield strength, good toughness, low cost, and strong corrosion resistance, thereby meeting the needs of the photovoltaic industry for cost reduction and efficiency improvement.

[0004] To achieve the above objectives, the present invention provides a high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel, comprising, based on 100% by mass, the following: C: 0.09%-0.15%, Si: 0.55%-0.80%, Mn: 0.8%-1.1%, Cr: 0.8%-1.2%, Ti: 0.03%-0.06%, Al: 0.20%-0.60%, Nb: 0.01%-0.03%, S≤0.006%, P≤0.035%, with the remainder being Fe and unavoidable impurities.

[0005] The weather resistance index of this invention satisfies the following formula: I=26.01×(Cu)+3.88×(Ni)+1.20×(Cr)+1.49×(Mo)+0.72×(Si)+0.85×(P)-1.50×(Mn)-0.35×(C)+4.2×(Ti)+2.8×(Al).

[0006] The weather resistance index reflects the corrosion resistance potential of steel in atmospheric environments; a higher value usually indicates better weather resistance.

[0007] like Figure 1 As shown, the present invention also provides a method for preparing the above-mentioned high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel, comprising the following preparation steps: S1. Pre-desulfurize the molten iron to obtain pre-desulfurized molten iron with a sulfur content ≤0.06%; S2. The pre-desulfurized molten iron is fed into the converter for blowing at a unit consumption of ≥780kg. Argon is blown from the bottom throughout the process. After smelting until the carbon content of the pre-desulfurized molten iron reaches 0.07%-0.095% and the temperature reaches 1620-1660℃, the steel is tapped using the double slag-blocking method. According to the chemical composition and mass percentage of the steel for high-strength, high-toughness, and high-corrosion-resistant photovoltaic brackets, silicon manganese, low-carbon ferrochrome, ferrosilicon, and aluminum blocks are added when 1 / 4 of the steel is tapped for deoxidation and alloying. When 1 / 3 of the steel is tapped, active lime slag is added for washing to obtain the rough molten steel. S3. The crude steel is fed into the LF furnace and refined until the sulfur content in the steel is ≤0.004%, the oxygen content is ≤30ppm, and the nitrogen content is ≤50ppm. Then, ferrotitanium is added until the titanium content in the crude steel reaches 0.03%-0.05%. Then, calcium treatment and soft blowing are carried out in sequence to obtain refined steel. S4. The refined molten steel is sequentially cast, slab heated, rolled and cooled, coiled and cooled to obtain high-strength, high-toughness and high-corrosion-resistant photovoltaic bracket steel.

[0008] In this invention, when the pre-desulfurized molten iron is fed into the converter in S2, the temperature of the pre-desulfurized molten iron is ≥1250℃, and the flow rate of bottom-blown argon gas is 200-300NL / min throughout the process; when the double slag-blocking method is used for tapping, the thickness of the slag is ≤50mm, and the total tapping time is ≥4min.

[0009] In this invention, the inlet temperature of the LF furnace in S3 is 1565-1585℃; the soft blowing time is ≥8min, and the outlet temperature of the LF furnace after soft blowing is 1560-1580℃.

[0010] In this invention, the continuous casting process in S4 includes: feeding refined molten steel into a continuous casting machine, the tundish of the continuous casting machine being superheated to 15-30°C, using an immersion-type long nozzle argon seal for protection during casting, the flow rate of argon gas from the stopper rod / top nozzle of the argon seal system being ≤7.5L / min, and adding an alkaline covering agent during casting; when the refined molten steel reaches the crystallizer, controlling the casting speed to 0.9-1.2m / min, using a three-stage light reduction, applying dynamic light reduction in the solids factor range of 0.6-0.8, reducing the thickness by 5-8mm, the reduction rate being 0.6-1.0mm / m, and the center segregation of the billet being ≤1.5 grade.

[0011] In this invention, the solid phase factor is the ratio of the solidification thickness of the billet to the billet thickness.

[0012] In this invention, the slab heating process in S4 includes: sending the continuously cast slab into a heating furnace and heating it to a temperature of 1050-1110℃ for 150-210 minutes.

[0013] In this invention, the rolling and cooling process in S4 includes: high-pressure descaling, rough rolling, finish rolling, and cooling performed sequentially; the cooling method includes ultra-fast cooling and layer cooling performed sequentially.

[0014] In this invention, the pressure of high-pressure dephosphorization is ≥22MPa, the final rolling temperature of roughing is 980-1050℃, the thickness of intermediate billet is 30-60mm, the initial rolling temperature of finishing rolling is ≤1050℃, the final rolling temperature of finishing rolling is 850-900℃, and the cross-sectional temperature difference of layer cooling is <20℃.

[0015] In this invention, the winding temperature in S4 is 580-630°C.

[0016] The present invention also provides the application of the above-mentioned high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel in photovoltaic supports.

[0017] The present invention has the following beneficial effects: This invention provides a high-strength, high-toughness, and high-corrosion-resistant photovoltaic bracket steel, which, based on 100% by mass, comprises: C: 0.09%-0.15%, Si: 0.55%-0.80%, Mn: 0.8%-1.1%, Cr: 0.8%-1.2%, Ti: 0.03%-0.06%, Al: 0.20%-0.60%, Nb: 0.01%-0.03%, S≤0.006%, P≤0.035%, with the remainder being Fe and unavoidable impurities.

[0018] In steel, Al can replace some Fe atoms in Fe3O4, forming a special FeAl2O4 film structure on the steel substrate surface. This film has cation-selective permeability and can effectively resist Cl. -It penetrates and enhances the corrosion resistance of steel; in addition, Al can react with N and C to generate high-melting-point AlC, AlN and other substances to refine the grains, and the Al2O3 formed by oxidation is enriched in the rust layer, providing protection for the internal steel reinforcement matrix.

[0019] Ti has a strong affinity for elements such as O, N, and C in steel, and can form stable oxides, carbides, and nitrides. These compounds act as nuclei during the solidification of molten steel, promoting grain nucleation and thus refining the steel grains. Titanium can also form a dense oxide film on the surface of steel, which can prevent the steel from contacting the external medium and improve the steel's corrosion resistance.

[0020] When the Cr content in steel reaches 0.8%-1.2%, Cr will form a dense oxide film (mainly Cr2O3) on the surface of the steel. This oxide film can prevent the steel matrix from being further oxidized and corroded, giving the steel good corrosion resistance and oxidation resistance. In addition, Cr can strengthen ferrite through solid solution, improve the strength and hardness of the steel, and maintain good toughness.

[0021] This invention achieves grain refinement, precipitation, and solid solution strengthening effects by adding Al, Ti, and Cr elements, thereby improving the strength and toughness of steel and promoting the formation of a dense and stable oxide film on its surface, significantly enhancing the corrosion resistance of the steel.

[0022] The high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel provided by this invention has a yield strength Rel≥500MPa, a tensile strength Rm≥600MPa, an elongation after fracture greater than 20%, and corrosion resistance more than twice that of Q460 grade high-strength photovoltaic support steel (salt spray test).

[0023] Instead of adding expensive alloying elements such as Ni and Mo to improve the corrosion resistance of steel, this invention uses low-cost elements such as Al, Ti, and Cr to improve the strength, toughness, and corrosion resistance of steel, which significantly reduces the cost of raw materials and makes it suitable for large-scale photovoltaic bracket applications.

[0024] This invention also employs a series of process steps, including converter smelting, LF furnace refining, slab heating, rolling and controlled cooling, coiling, and cooling, to ensure uniform composition and fine microstructure of the steel used in photovoltaic brackets. By controlling the process parameters in each step, microstructure regulation is achieved, ensuring the strength and plasticity of the steel used in photovoltaic brackets.

[0025] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0026] Figure 1 This is a flowchart of a method for preparing high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel provided by the present invention; Figure 2This is a metallographic image of the high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel prepared in Example 1 of the present invention. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0028] Example 1 A high-strength, high-toughness, and high-corrosion-resistant steel for photovoltaic brackets, comprising, by weight (100%): C: 0.12%, Si: 0.70%, Mn: 0.95%, Cr: 1.0%, Ti: 0.045%, Al: 0.40%, Nb: 0.02%, S: 0.005%, P: 0.03%, with the remainder being Fe and unavoidable impurities.

[0029] The preparation method of the above-mentioned high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel includes the following preparation steps: S1. Pre-desulfurize the molten iron to obtain pre-desulfurized molten iron with a sulfur content of 0.055%; S2. Pre-desulfurized molten iron (temperature 1270℃) is fed into the converter at a unit consumption of 790kg. Argon is blown into the bottom throughout the process (argon flow rate is 250NL / min). After smelting until the carbon content of the pre-desulfurized molten iron reaches 0.08% and the temperature reaches 1625℃, the steel is tapped using the double slag-blocking method (slag thickness is 40mm). According to the chemical composition and mass percentage of the high-strength, high-toughness, and high-corrosion-resistant photovoltaic bracket steel mentioned above, silicon manganese, low-carbon ferrochrome, ferrosilicon, and aluminum blocks are added when the steel is tapped 1 / 4 for deoxidation and alloying. When the steel is tapped 1 / 3, active lime slag is added for washing. The total tapping time is 4.5min, and the rough molten steel is obtained. S3. The crude steel is fed into the LF furnace. The inlet temperature of the LF furnace is 1570℃. After refining the steel to a sulfur content of 0.003%, an oxygen content of 25ppm, and a nitrogen content of 45ppm, ferrotitanium is added. Then, calcium treatment is carried out in sequence. After the calcium treatment is completed, soft blowing is performed for 10 minutes. The outlet temperature of the LF furnace is 1567℃, and refined steel is obtained. S4. Continuous casting: Refined molten steel is fed into the continuous casting machine. The tundish of the continuous casting machine is superheated to 20°C. The casting is protected by argon sealing with an immersion-type long nozzle (the flow rate of argon gas from the stopper rod / top nozzle of the argon sealing system is 6.5 L / min). An alkaline covering agent is added during casting. When the refined molten steel reaches the crystallizer, the casting speed is controlled at 1.1 m / min. Three-stage light reduction is used, with a reduction thickness of 6 mm and a reduction rate of 0.8 mm / m, to obtain a slab with a center segregation grade of 1.5. Slab heating: The slab after continuous casting is sent into a heating furnace and heated to a temperature of 1080℃ for 180 minutes. Rolling and controlled cooling: After the slab is heated, it is descaled under high pressure (pressure 23MPa). The rough rolling is carried out in 3+3 passes (final rolling temperature 1020℃), and the intermediate slab thickness is 45mm. The starting rolling temperature of the finish rolling is 1040℃, and the final rolling temperature is 880℃. After the finish rolling, ultra-fast cooling and layer cooling are activated for coordinated cooling. The coiling temperature is 600℃, and after coiling, it is cooled to obtain high-strength, high-toughness, and high-corrosion-resistant photovoltaic bracket steel.

[0030] Example 2 A high-strength, high-toughness, and high-corrosion-resistant steel for photovoltaic brackets, comprising, by weight (100%): C: 0.09%, Si: 0.55%, Mn: 0.8%, Cr: 0.8%, Ti: 0.03%, Al: 0.20%, Nb: 0.01%, S: 0.006%, P: 0.035%, with the remainder being Fe and unavoidable impurities.

[0031] The preparation method of the above-mentioned high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel includes the following preparation steps: S1. Pre-desulfurize the molten iron to obtain pre-desulfurized molten iron with a sulfur content of 0.050%; S2. Pre-desulfurized molten iron (temperature 1280℃) is fed into the converter at a unit consumption of 780kg. Argon is blown into the bottom throughout the process (argon flow rate is 200NL / min). After smelting until the carbon content of the pre-desulfurized molten iron reaches 0.07% and the temperature reaches 1620℃, the steel is tapped using the double slag-blocking method (slag thickness is 30mm). According to the chemical composition and mass percentage of the high-strength, high-toughness, and high-corrosion-resistant photovoltaic bracket steel mentioned above, silicon manganese, low-carbon ferrochrome, ferrosilicon, and aluminum blocks are added when the steel is tapped 1 / 4 for deoxidation and alloying. When the steel is tapped 1 / 3, active lime slag is added for washing. The total tapping time is 4.2min, and the rough molten steel is obtained. S3. The crude steel is fed into the LF furnace. The inlet temperature of the LF furnace is 1562℃. After refining the steel to a sulfur content of 0.004%, an oxygen content of 28ppm, and a nitrogen content of 48ppm, ferrotitanium is added. Then, calcium treatment is carried out in sequence. After the calcium treatment is completed, soft blowing is performed for 8 minutes. The outlet temperature of the LF furnace is 1560℃, and refined steel is obtained. S4. Continuous casting: Refined molten steel is fed into the continuous casting machine. The tundish of the continuous casting machine is superheated to 15°C. The casting is protected by argon sealing with an immersion-type long nozzle (the flow rate of argon gas from the stopper rod / top nozzle of the argon sealing system is 5.5 L / min). An alkaline covering agent is added during casting. When the refined molten steel reaches the crystallizer, the casting speed is controlled at 1.2 m / min. Three-stage light reduction is used, with a reduction thickness of 8 mm and a reduction rate of 0.8 mm / m, to obtain a slab with a center segregation grade of 0.5. Slab heating: The slab after continuous casting is sent into a heating furnace and heated to 1050℃ for 150 minutes. Rolling and controlled cooling: After the slab is heated, it is descaled under high pressure (pressure 22MPa). The rough rolling is carried out in 3+3 passes (final rolling temperature 980℃), and the intermediate slab thickness is 30mm. The starting rolling temperature of the finish rolling is 1020℃, and the final rolling temperature is 850℃. After the finish rolling, ultra-fast cooling and layer cooling are activated for coordinated cooling. The coiling temperature is 580℃, and after coiling, it is cooled to obtain high-strength, high-toughness, and high-corrosion-resistant photovoltaic bracket steel.

[0032] Example 3 A high-strength, high-toughness, and high-corrosion-resistant steel for photovoltaic brackets, comprising, by weight (100%): C: 0.15%, Si: 0.80%, Mn: 1.1%, Cr: 1.2%, Ti: 0.06%, Al: 0.60%, Nb: 0.03%, S: 0.004%, P: 0.025%, with the remainder being Fe and unavoidable impurities.

[0033] The preparation method of the above-mentioned high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel includes the following preparation steps: S1. Pre-desulfurize the molten iron to obtain pre-desulfurized molten iron with a sulfur content of 0.058%; S2. Pre-desulfurized molten iron (temperature 1260℃) is fed into the converter at a unit consumption of 800kg. Argon is blown into the bottom throughout the process (argon flow rate is 300NL / min). After smelting until the carbon content of the pre-desulfurized molten iron reaches 0.095% and the temperature reaches 1660℃, the steel is tapped using the double slag-blocking method (slag thickness is 50mm). According to the chemical composition and mass percentage of the high-strength, high-toughness, and high-corrosion-resistant photovoltaic bracket steel mentioned above, silicon manganese, low-carbon ferrochrome, ferrosilicon, and aluminum blocks are added when the steel is tapped 1 / 4 for deoxidation and alloying. When the steel is tapped 1 / 3, active lime slag is added for washing. The total tapping time is 5min, and the rough molten steel is obtained. S3. The crude steel is fed into the LF furnace. The inlet temperature of the LF furnace is 1583℃. After refining the steel to a sulfur content of 0.002%, an oxygen content of 20ppm, and a nitrogen content of 40ppm, ferrotitanium is added. Then, calcium treatment is carried out in sequence. After the calcium treatment is completed, soft blowing is performed for 12 minutes. The outlet temperature of the LF furnace is 1580℃, and refined steel is obtained. S4. Continuous Casting: Refined molten steel is fed into the continuous casting machine. The tundish of the continuous casting machine is superheated to 30°C. The casting is protected by argon sealing with an immersion-type long nozzle (the flow rate of argon gas from the stopper rod / top nozzle of the argon sealing system is 7.5 L / min). An alkaline covering agent is added during casting. When the refined molten steel reaches the crystallizer, the casting speed is controlled at 0.9 m / min. Three-stage light reduction is used, with a reduction thickness of 6 mm and a reduction rate of 1.0 mm / m, to obtain a slab with a center segregation grade of 1.5. Slab heating: The slab after continuous casting is sent into a heating furnace and heated to 1110℃ for 210 minutes. Rolling and controlled cooling: After the slab is heated, it is descaled under high pressure (25MPa). The rough rolling is carried out in 3+3 passes (final rolling temperature 1050℃), and the intermediate slab thickness is 60mm. The starting rolling temperature of the finish rolling is 1050℃, and the final rolling temperature is 900℃. After the finish rolling, ultra-fast cooling and layer cooling are activated for coordinated cooling. The coiling temperature is 630℃, and after coiling, it is cooled to obtain high-strength, high-toughness, and high-corrosion-resistant photovoltaic bracket steel.

[0034] Example 4 A high-strength, high-toughness, and high-corrosion-resistant steel for photovoltaic brackets, comprising, by weight (100%): C: 0.10%, Si: 0.60%, Mn: 1.0%, Cr: 1.0%, Ti: 0.04%, Al: 0.50%, Nb: 0.02%, S: 0.003%, P: 0.025%, with the remainder being Fe and unavoidable impurities.

[0035] The preparation method of the above-mentioned high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel includes the following preparation steps: S1. Pre-desulfurize the molten iron to obtain pre-desulfurized molten iron with a sulfur content of 0.052%; S2. Pre-desulfurized molten iron (temperature 1275℃) is fed into the converter at a unit consumption of 785kg. Argon is blown into the bottom throughout the process (argon flow rate is 270NL / min). After smelting until the carbon content of the pre-desulfurized molten iron reaches 0.085% and the temperature reaches 1640℃, the steel is tapped using the double slag-blocking method (slag thickness is 45mm). According to the chemical composition and mass percentage of the high-strength, high-toughness, and high-corrosion-resistant photovoltaic bracket steel mentioned above, silicon manganese, low-carbon ferrochrome, ferrosilicon, and aluminum blocks are added when the steel is tapped 1 / 4 for deoxidation and alloying. When the steel is tapped 1 / 3, active lime slag is added for washing. The total tapping time is 4.8min, and molten steel is obtained. S3. The molten steel is fed into the LF furnace. The inlet temperature of the LF furnace is 1578℃. After refining the molten steel to a sulfur content of 0.0025%, an oxygen content of 22ppm, and a nitrogen content of 42ppm, ferrotitanium is added. Then, calcium treatment is carried out in sequence. After the calcium treatment is completed, soft blowing is performed for 9 minutes. The outlet temperature of the LF furnace is 1575℃, and refined molten steel is obtained. S4. Continuous Casting: Refined molten steel is fed into the continuous casting machine. The tundish of the continuous casting machine is superheated to 25°C. The casting is protected by argon sealing with an immersion-type long nozzle (the flow rate of argon gas from the stopper rod / top nozzle of the argon sealing system is 7.0 L / min). An alkaline covering agent is added during casting. When the refined molten steel reaches the crystallizer, the casting speed is controlled at 1.0 m / min. Three-stage light reduction is used, with a reduction thickness of 8 mm and a reduction rate of 0.8 mm / m, to obtain a slab with a center segregation grade of 1.0. Slab heating: The slab after continuous casting is sent into a heating furnace and heated to a temperature of 1090℃ for 190 minutes. Rolling and controlled cooling: After the slab is heated, it is descaled under high pressure (pressure 24MPa). The rough rolling is carried out in 3+3 passes (final rolling temperature 1000℃), and the intermediate slab thickness is 50mm. The starting rolling temperature of the finish rolling is 1030℃, and the final rolling temperature is 870℃. After the finish rolling, ultra-fast cooling and layer cooling are started for coordinated cooling. The coiling temperature is 610℃, and after coiling, it is cooled to obtain high-strength, high-toughness, and high-corrosion-resistant photovoltaic bracket steel.

[0036] Characterization tests: The high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel prepared in Example 1 was observed using a metallographic microscope, and its metallographic image is shown below. Figure 2 As shown. From Figure 2 It can be seen that the metallographic structure of the high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel prepared in Example 1 is ferrite + pearlite.

[0037] Performance testing: Standard tensile specimens were designed with reference to the national standard GB / T228.1-2021 "Metallic materials, tensile testing - Part 1: Test method at room temperature". The mechanical properties of the rolled specimens were tested using a DDL200 universal testing machine with a 50kN sensor and a tensile rate set to 1mm / min. Each type of steel was tested three times and the average value was taken to calculate the yield strength, tensile strength and elongation.

[0038] The corrosion resistance rate of high-strength, high-toughness, and high-corrosion-resistant photovoltaic (PV) bracket steel was determined by simulating corrosion in a chloride ion environment. The corrosion rate was calculated using ordinary Q460 grade high-strength PV bracket steel as a benchmark. The test standard referenced GB / T10125-2021, and the test equipment was a GP / SP1100D composite salt spray drying corrosion test chamber. The chamber temperature was set at 45℃, the saturation tank temperature at 47℃, the intermittent spray cycle was 1 hour (12 minutes of spraying followed by 48 minutes of drying at 70℃), the number of cycles was tentatively set at 144, the spray pressure was 0.10 MPa, and the spray volume was adjusted to the maximum. The test solution used was a sodium chloride solution with a mass fraction of 5.00% ± 0.05%. The results are shown in Table 1.

[0039] Table 1 Performance Test Results

[0040] As can be seen from Table 1, the high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel provided by this invention has a yield strength of over 500 MPa, and its corrosion rate is reduced by more than 50% compared with commercially available Q460 high-strength photovoltaic support steel.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A high-strength, high-toughness, and high-corrosion-resistant steel for photovoltaic brackets, characterized in that, Based on 100% by weight of the steel used in high-strength, high-toughness, and high-corrosion-resistant photovoltaic brackets, it includes: C: 0.09%-0.15%, Si: 0.55%-0.80%, Mn: 0.8%-1.1%, Cr: 0.8%-1.2%, Ti: 0.03%-0.06%, Al: 0.20%-0.60%, Nb: 0.01%-0.03%, S≤0.006%, P≤0.035%, with the remainder being Fe and unavoidable impurities.

2. The method for preparing high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel according to claim 1, characterized in that, The preparation steps include the following: S1. Pre-desulfurize the molten iron to obtain pre-desulfurized molten iron with a sulfur content ≤0.06%; S2. The pre-desulfurized molten iron is fed into the converter for blowing at a unit consumption of ≥780kg. Argon is blown from the bottom throughout the process. After smelting until the carbon content of the pre-desulfurized molten iron reaches 0.07%-0.095% and the temperature is 1620-1660℃, the steel is tapped using the double slag-blocking method. According to the chemical composition and mass percentage of the steel for high-strength, high-toughness, and high-corrosion-resistant photovoltaic brackets, silicon manganese, low-carbon ferrochrome, ferrosilicon, and aluminum blocks are added when 1 / 4 of the steel is tapped for deoxidation and alloying. When 1 / 3 of the steel is tapped, active lime slag is added for washing to obtain the rough molten steel. S3. The crude steel is fed into the LF furnace and refined until the sulfur content in the steel is ≤0.004%, the oxygen content is ≤30ppm, and the nitrogen content is ≤50ppm. Then, ferrotitanium is added until the titanium content in the crude steel reaches 0.03%-0.05%. Then, calcium treatment and soft blowing are carried out in sequence to obtain refined steel. S4. The refined molten steel is sequentially cast, slab heated, rolled and cooled, coiled and cooled to obtain high-strength, high-toughness and high-corrosion-resistant photovoltaic bracket steel.

3. The method for preparing high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel according to claim 2, characterized in that, When pre-desulfurized molten iron is fed into the converter in S2, the temperature of the pre-desulfurized molten iron is ≥1250℃, and the flow rate of bottom-blown argon gas is 200-300NL / min throughout the process; when the double slag-blocking method is used for tapping, the thickness of the slag is ≤50mm, and the total tapping time is ≥4min.

4. The method for preparing high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel according to claim 2, characterized in that, The inlet temperature of S3 when it is fed into the LF furnace is 1565-1585℃; The soft blowing time is ≥8min, and the outlet temperature of the LF furnace after soft blowing is 1560-1580℃.

5. The method for preparing high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel according to claim 2, characterized in that, The continuous casting process in S4 includes: feeding refined molten steel into the continuous casting machine, with the tundish superheated to 15-30℃; using immersion-type long nozzle argon sealing protection for casting; the flow rate of argon gas from the stopper rod / top nozzle of the argon sealing system ≤7.5L / min; adding an alkaline covering agent during casting; when the refined molten steel reaches the crystallizer, controlling the casting speed to 0.9-1.2m / min; using three-stage light reduction; applying dynamic light reduction within the solids factor range of 0.6-0.8; reducing the thickness to 5-8mm; reducing the rate to 0.6-1.0mm / m; and ensuring that the center segregation of the billet is ≤1.5 grade.

6. The method for preparing high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel according to claim 2, characterized in that, The slab heating process in S4 includes: sending the continuously cast slab into the heating furnace and heating it to a temperature of 1050-1110℃ for 150-210 minutes.

7. The method for preparing high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel according to claim 2, characterized in that, The rolling and cooling process in S4 includes: high-pressure descaling, rough rolling, finish rolling, and cooling in sequence; the cooling methods include ultra-fast cooling and layer cooling in sequence.

8. The method for preparing high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel according to claim 7, characterized in that, The pressure for high-pressure dephosphorization is ≥22MPa, the final rolling temperature of roughing is 980-1050℃, the thickness of intermediate slab is 30-60mm, the initial rolling temperature of finishing rolling is ≤1050℃, the final rolling temperature of finishing rolling is 850-900℃, and the cross-sectional temperature difference of layer cooling is <20℃.

9. The method for preparing high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel according to claim 2, characterized in that, The winding temperature in S4 is 580-630℃.

10. The application of the high-strength, high-toughness, and high-corrosion-resistant photovoltaic support steel as described in claim 1 in photovoltaic supports.

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