High-strength and high-corrosion-resistant zinc-aluminum-magnesium steel, preparation method and application thereof

Abstract

The application relates to a high-strength and high-corrosion-resistance zinc-aluminum-magnesium steel and a preparation method and application thereof. The high-strength and high-corrosion-resistance zinc-aluminum-magnesium steel comprises a base material and a plating layer, and the base material is composed of the following components in percentage by mass: C: 0.10% or less, Si: 0.02%-0.50%, Mn: 1.00%-3.00%, P: 0.030% or less, S: 0.005% or less, Nb: 0.01%-0.08%, Ti: 0.01%-0.08%, and the balance of Fe and inevitable impurities; and the plating layer is composed of the following components in percentage by mass: Al: 6.0%-15.0%, Mg: 1.0%-5.0%, Si: 0.1%-1.6%, Sn: 0%-0.2%, and the balance of Zn and inevitable impurities. The high-strength and high-corrosion-resistance zinc-aluminum-magnesium steel is prepared by adopting a hot-rolling thin slab continuous casting and rolling CSP process to produce a high-strength thin-gauge base material, and then hot-dip plating, and finally obtaining the high-strength zinc-aluminum-magnesium steel for a coastal beach photovoltaic support. The high-strength and high-corrosion-resistance zinc-aluminum-magnesium steel has excellent mechanical and corrosion-resistance properties, and the photovoltaic support made of the high-strength and high-corrosion-resistance zinc-aluminum-magnesium steel not only greatly reduces the cost of the support in the whole life cycle, but also has small environmental pollution and low resource consumption.

Description

Technical Field

[0001] This invention relates to the fields of steel and photovoltaic power generation technology, specifically to a high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel, its preparation method, and its applications. Background Technology

[0002] With the promotion of national policies and the development of the photovoltaic industry, the steel consumption in the photovoltaic sector has increased significantly. Photovoltaic support structures are the fundamental structure of solar photovoltaic power plants, and their designed service life should be no less than 25 years. Therefore, the requirements for the corrosion resistance of photovoltaic support structures are extremely high. Currently, most photovoltaic projects in China typically use traditional Q235 steel for support structures, which undergo forming, pickling, and hot-dip galvanizing for corrosion protection. To ensure the strength and safety of the support structures, thicker (4-12mm) hot-dip galvanized Q235 steel is usually used.

[0003] In recent years, with the gradual elimination of photovoltaic subsidies and the large-scale application for grid parity projects, enterprises have increasingly stringent requirements for cost control of photovoltaic (PV) mounting systems. Traditional hot-dip galvanized steel mounting systems, due to their significant environmental pollution, low process efficiency, high resource consumption, and low quality, can no longer meet the project's cost control requirements. On the other hand, with the decreasing availability of high-quality sites for PV power plants, more and more PV power plants are being built in harsh environments such as coastal mudflats. The results of many practical applications in coastal mudflat areas show that traditional PV mounting systems still suffer from severe corrosion in marine atmospheric environments and cannot meet service safety requirements.

[0004] In summary, given the development trend of green, low-carbon, high-strength, and corrosion-resistant photovoltaic industry, developing a high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel for photovoltaic brackets is an urgent need for the photovoltaic industry. Summary of the Invention

[0005] One objective of this invention is to provide a high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel, comprising a substrate and a coating attached to the surface of the substrate. The substrate has the following mass percentage composition: C ≤ 0.10%, Si: 0.02%–0.50%, Mn: 1.00%–3.00%, P ≤ 0.030%, S ≤ 0.005%, Nb: 0.01%–0.08%, Ti: 0.01%–0.08%, with the balance being Fe and unavoidable impurities. The coating has the following mass percentage composition: Al: 6.0%–15.0%, Mg: 1.0%–5.0%, Si: 0.1%–1.6%, Sn: 0%–0.2%, with the balance being Zn and unavoidable impurities.

[0006] Furthermore, the substrate has the following mass percentage composition: C: 0.03%–0.06%, Si: 0.20%–0.40%, Mn: 1.50%–2.00%, P≤0.010%, S≤0.005%, Nb: 0.02%–0.04%, Ti: 0.03%–0.06%, with the balance being Fe and unavoidable impurities.

[0007] Furthermore, the mass percentage composition of the coating is as follows: Al: 8.0%–12.0%, Mg: 2.0%–4.0%, Si: 0.2%–0.4%, Sn: 0.05%–0.15%, with the balance being Zn and unavoidable impurities, and 1 / 4 < Mg / Al < 1 / 2.

[0008] Furthermore, the high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel has a yield strength ≥500MPa, a tensile strength of 600~760MPa, an elongation ≥18%, and a thickness of 0.5~2mm.

[0009] The second objective of this invention is to provide a method for preparing the above-mentioned high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel. The method includes the following steps: first, high-strength thin-gauge cold-rolled raw materials (i.e., base materials) are produced by hot-rolled thin slab continuous casting and rolling CSP process, and then hot-dip galvanizing is performed.

[0010] Furthermore, the specific process of the continuous casting and rolling (CSP) process includes: refining → thin slab continuous casting → soaking furnace → rough rolling → finish rolling → laminar flow cooling → coiling.

[0011] Furthermore, the initial rolling temperature of the finishing mill is controlled at 950–850℃, preferably 920–870℃; the final rolling temperature is controlled at 750–820℃, preferably 770–810℃; and laminar cooling is performed to 100–300℃ at a cooling rate of 20–35℃ / s.

[0012] Furthermore, the specific process of hot-dip galvanizing is as follows: pickling of CSP cold-rolled raw material → annealing → hot-dip galvanizing → coiling.

[0013] Furthermore, during the hot-dip galvanizing stage, the strip steel is heated to 600–700℃ for 50–120 seconds, and then cooled to a temperature 10–30℃ higher than the galvanizing solution temperature at a rate of 40–80℃ / s, with the galvanizing solution temperature controlled at 500–540℃.

[0014] The third objective of this invention is to provide an application of the aforementioned high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel in photovoltaic supports for coastal mudflats.

[0015] This invention addresses a series of problems inherent in the manufacturing and use of traditional hot-dip galvanized steel photovoltaic (PV) brackets, including significant environmental pollution, low process efficiency, high resource consumption, low strength, and severe corrosion when applied in marine atmospheric environments. It develops a novel high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel for coastal tidal flat PV brackets, which can be used exposed in environments with corrosion ratings of C4 and above. Compared to traditional hot-dip galvanized PV brackets, the high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel provided by this invention significantly reduces the total life-cycle cost of PV brackets, while also minimizing environmental pollution and resource consumption, demonstrating significant application value.

[0016] The working principles of the main elements and their contents in the high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel substrate described in this invention are as follows:

[0017] The carbon content should be controlled at ≤0.10%. Carbon is an effective element for improving steel strength. When the carbon content is high (e.g., exceeding 0.12%), martensite is easily formed, which deteriorates the low-temperature toughness of the steel, and the tensile strength is also prone to exceeding the upper limit, with a greater impact on weldability. When the carbon content in the steel is below 0.10% (wt), the carbon equivalent of the steel is not very sensitive to cold cracking in welding, and reducing the carbon content can effectively improve the low-temperature toughness of the steel. However, when the carbon content is too low (e.g., less than 0.03%), it will lead to insufficient strength of the steel plate, less hard phase in the steel, and difficulty in controlling the yield strength ratio. Therefore, the carbon content is preferably between 0.03% and 0.06%.

[0018] The Si content is controlled between 0.02% and 0.50%. While adding Si can improve the corrosion resistance of the substrate, in the marine atmospheric environment of coastal mudflats, adding a certain amount of Si weakens the formation of the α-FeOOH phase due to the presence of silicon-oxygen tetrahedral compounds, leading to increased anion selectivity in the rust layer. This ultimately reduces the protective ability of the rust layer, resulting in a deterioration in the corrosion resistance of the substrate. Furthermore, because Si has a stronger affinity for oxygen than iron, it easily forms low-melting-point silicates during welding, increasing the fluidity of slag and molten metal. Excessive Si addition reduces the weldability and impact toughness of the steel. Therefore, for photovoltaic support steel used in coastal mudflats, the Si content in this invention is preferably between 0.20% and 0.40%.

[0019] The Mn content is controlled between 1.00% and 3.00%. Mn is an important strengthening and toughening element, an austenite stabilizing element, and can expand the austenite region in the iron-carbon phase diagram, promoting the mid-temperature microstructure transformation. High Mn content easily leads to severe central segregation in steel, deteriorating the low-temperature toughness of the steel and making the HAZ (high-temperature zone) of the steel plate prone to cracking during welding. This is unnecessary for the mechanical properties of the steel of this invention. Conversely, too low an Mn content easily reduces the strength of the steel. Therefore, the Mn content in this invention is preferably between 1.50% and 2.00%.

[0020] P ≤ 0.010%. Higher P content significantly improves the weather resistance of steel, but at the same time reduces the weldability of steel, increases the tendency of steel to become brittle in cold, and produces more serious central segregation.

[0021] S ≤ 0.005%. Higher S content will reduce the corrosion resistance, low-temperature toughness, and Z-axis properties of steel.

[0022] The Nb content is 0.01% to 0.08%. The solid solution strengthening effect of Nb can improve the yield strength of steel, and its grain-refining effect can also improve impact toughness, which is beneficial to weldability. In this invention, the optimal Nb content is preferably 0.02% to 0.04%.

[0023] The Ti content is 0.01%–0.08%. Ti is beneficial for steel deoxidation, reduces inclusions in the steel, and improves the impact toughness of the steel. Adding Ti can reduce the electrochemical reactivity of the steel, which is beneficial for improving the steel's resistance to marine atmospheric corrosion. However, excessive Ti content will reduce the low-temperature toughness of the steel. Therefore, the optimal Ti content is preferably 0.03%–0.06%.

[0024] The main components of the coating of this invention are zinc, aluminum, magnesium, silicon, and tin, and it contains no other components. The main functions of each element in the coating are as follows:

[0025] The Al content is 6.0%–15.0%. Al forms aluminum-rich compounds in the coating, which can inhibit the reaction between zinc and iron, thin the Fe-Zn compound layer, and simultaneously form aluminum oxides to suppress the adverse effects of loose magnesium oxides, thus improving coating adhesion. Secondly, adding Al to zinc plating significantly improves corrosion resistance and heat resistance. However, when the Al content is high, the improvement in corrosion resistance is not significant enough, and it leads to more zinc ash and dross, and even the formation of dendritic aluminum-rich phases, resulting in a decrease in coating surface quality. Furthermore, tensile strength, elongation, and hardness initially increase and then decrease with increasing Al content. Therefore, considering all factors, the optimal Al content is preferably 8.0%–12.0%.

[0026] The Mg content is 1.0%–5.0%. The corrosion resistance of the coating significantly increases with increasing Mg content, as Mg reacts with the Zn element in the plating solution. The corrosion products are mainly dense basic zinc chloride, which inhibits the formation of basic zinc carbonate and zinc oxide. However, when the Mg content is too high, significant Mg oxides form on the plating solution surface. This not only increases the amount of slag but also carries the oxidation from the plating solution surface to the strip steel surface, affecting the surface quality and increasing production difficulty. Therefore, the optimal Mg content is preferably 2.0%–4.0%, with 1 / 4 < Mg / Al < 1 / 2.

[0027] The Si content is 0.1%–1.6%. Adding a small amount of Si to the plating bath can significantly inhibit the diffusion and chemical reaction between Fe and Al, improve fluidity and wettability between the plating bath and the steel substrate, reduce iron loss and zinc dross, and also regulate the growth of Fe-Al compounds at the interface between the steel substrate and the coating, improving the adhesion between the coating and the steel plate. However, excessive Si content is also detrimental to the Fe-Al reaction on the substrate and can cause a large amount of dross in the zinc pot. In addition, in marine environments, the corrosion resistance of the material will decrease significantly when the Si content exceeds 0.5%. Therefore, the optimal Si content is preferably 0.2%–0.4%.

[0028] The Sn content is 0%–0.2%. Traditional zinc-aluminum-magnesium (ZAMg) products still have corrosion resistance issues in marine atmospheric environments. Sn can increase the self-corrosion potential of the coating, reduce electrochemical reactivity, and the formed SnO2 can improve the ion selectivity of the coating, preventing further corrosion of the coating by Cl ions and improving its corrosion resistance. Sn entering the ZnO lattice can inhibit the oxidation rate of Zn, reducing the coating corrosion rate. The compound particles formed by Sn and Zn can improve the bonding force of the eutectic structure. Excessive Sn content will impair the toughness of the steel and reduce weldability. Therefore, the optimal Sn content is preferably 0.05%–0.15%.

[0029] Compared with existing similar products and processes, the advantages of this invention are mainly reflected in the following aspects:

[0030] (1) Compared with the Q235 grade steel commonly used in the photovoltaic industry, the high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel substrate provided by this invention is manufactured using the CSP process. By strictly controlling the Mn element and adding strengthening elements such as Nb and Ti, it achieves a yield strength ≥500MPa, a tensile strength of 600-760MPa, and an elongation ≥18% when the thickness is 0.5-2mm. This invention not only improves the strength but also reduces the thickness of the photovoltaic bracket, thereby greatly reducing the amount of steel used per unit photovoltaic bracket.

[0031] (2) In manufacturing high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel, this invention improves the coating adhesion and corrosion resistance in marine environments by adding the element Sn to the plating bath. Strict control of the Si content in the substrate and coating not only avoids corrosion deterioration caused by excessive Si content in marine atmospheric environments but also ensures the comprehensive mechanical, weldability, and other properties of the steel. Tests were conducted according to GB / T24195-2009 "Corrosion of Metals and Alloys - Acidic Salt Spray, Cyclic Accelerated Corrosion Tests under 'Dry' and 'Wet' Conditions," and the results show that its resistance to marine atmospheric corrosion is 3-4 times that of traditional hot-dip galvanized steel and 70% higher than that of conventional hot-dip galvanized aluminum-magnesium steel.

[0032] (3) The high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel provided by this invention can be used to manufacture photovoltaic brackets for coastal mudflats. These photovoltaic brackets can be used in environments with a corrosion level of C4 or higher for extended periods. Compared with traditional hot-dip galvanized photovoltaic brackets, the photovoltaic bracket products provided by this invention significantly reduce the cost of the bracket's entire life cycle. In addition, they have advantages such as low environmental pollution and low resource consumption, thus having a good market prospect. Attached Figure Description

[0033] Figure 1 This is a comparison chart of corrosion resistance test results for different samples. Detailed Implementation

[0034] To enable those skilled in the art to fully understand the technical solution and beneficial effects of the present invention, the following detailed description is provided in conjunction with specific embodiments.

[0035] This invention provides a high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel for photovoltaic supports in coastal mudflats, comprising a substrate and a coating. The high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel has a thickness of 0.5–2 mm, a yield strength ≥500 MPa, a tensile strength of 600–760 MPa, and an elongation ≥18%. Under cyclic corrosion testing conditions, its resistance to marine atmospheric corrosion is 3–4 times that of traditional hot-dip galvanized steel, and 70% higher than that of conventional hot-dip galvanized aluminum-magnesium steel.

[0036] The chemical composition and mass percentage of the substrate are as follows: C ≤ 0.10%, Si: 0.02%–0.50%, Mn: 1.00%–3.00%, P ≤ 0.030%, S ≤ 0.005%, Nb: 0.01%–0.08%, Ti: 0.01%–0.08%, with the balance being Fe and unavoidable impurities. The chemical composition and mass percentage of the coating are as follows: Al: 6.0%–15.0%, Mg: 1.0%–5.0%, Si: 0.1%–1.6%, Sn: 0%–0.2%, with the balance being Zn and unavoidable impurities.

[0037] Preferably, the substrate of the high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel for coastal photovoltaic supports comprises the following chemical composition by weight percentage: C: 0.03%–0.06%, Si: 0.20%–0.40%, Mn: 1.50%–2.00%, P≤0.010%, S≤0.005%, Nb: 0.02%–0.04%, Ti: 0.03%–0.06%, with the balance being Fe and unavoidable impurities. Simultaneously, the coating of the high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel for coastal photovoltaic supports comprises the following chemical composition by weight percentage: Al: 8.0%–12.0%, Mg: 2.0%–4.0%, Si: 0.2%–0.4%, Sn: 0.05%–0.15%, with the balance being Zn and unavoidable impurities.

[0038] The above-mentioned preparation method for high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel for photovoltaic supports in coastal mudflats is divided into substrate preparation and coating preparation. The substrate is produced using a hot-rolled thin slab continuous casting and rolling (CSP) process to produce high-strength, thin-gauge cold-rolled raw materials, mainly including the following steps: refining → thin slab continuous casting → soaking furnace → rough rolling → finish rolling → laminar flow cooling → coiling. The coating preparation mainly includes the following steps: CSP cold-rolled raw material pickling → annealing → hot-dip galvanizing → coiling. The CSP process for substrate preparation not only reduces production costs but also shortens the production cycle, resulting in high-strength substrates. During this process, the initial finishing rolling temperature is controlled at 950–850℃, and the final rolling temperature at 750–820℃. The preferred initial finishing rolling temperature is 920–870℃, and the preferred final rolling temperature is 770–810℃. This is because excessively high initial rolling temperatures can easily lead to mixed crystals, while excessively low initial rolling temperatures cannot guarantee an effective final rolling temperature. When the final rolling temperature is too high or too low, it is difficult to generate the required hard-soft multiphase structure, and the strength and toughness of the steel will be affected. Furthermore, the cooling rate during the laminar flow cooling stage is 20–35 °C / s, rapidly cooling the steel sheet from approximately 770 °C to 100–300 °C, ensuring the transformation of the hard phase structure of the substrate. After pickling and rolling, the strip is hot-dip galvanized. During the hot-dip galvanizing stage, the strip is heated to 600–700 °C for 50–120 seconds, then cooled to a temperature 10–30 °C higher than the galvanizing bath temperature at a cooling rate of 40–80 °C / s, while the galvanizing bath temperature is controlled at 500–540 °C. Finally, a post-treatment agent is applied to the surface of the coated steel strip to passivate the coating, enabling it to be used as a photovoltaic support.

[0039] Following the above process flow, the various substrates with the formulas shown in Table 1 were first prepared. Then, the plating solutions shown in Table 2 were prepared to perform hot-dip plating on the various substrates, and finally a series of high-strength, high-corrosion-resistant zinc-aluminum-magnesium steels for coastal tidal photovoltaic brackets were obtained.

[0040] Table 1. Chemical composition (wt.%) of different substrates

[0041] Substrate Number C Si Mn P S Nb Ti A 0.03 0.32 1.20 0.007 0.002 0.02 0.02 B 0.04 0.24 1.60 0.008 0.003 0.04 0.02 C 0.05 0.32 1.82 0.007 0.003 0.06 0.02 D 0.03 0.31 2.12 0.007 0.002 0.04 0.03 E 0.03 0.22 1.80 0.008 0.002 0.04 0.04

[0042] Table 2. Chemical composition (wt.%) of different plating solutions

[0043] serial number Al Mg Si Sn 1 8 2 1.6 0 2 10 3 1.6 0 3 12 4 1.6 0 4 10 3 0.8 0 5 10 2.5 0.4 0.05 6 10 3 0.3 0.10 7 11 3 0.3 0.15

[0044] Mechanical tests were conducted on samples of high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel used for photovoltaic supports on various coastal mudflats. The results are shown in Table 3 below.

[0045] Table 3 Mechanical Properties of Different High-Strength and High-Corrosion-Resistant Zinc-Aluminum-Magnesium Steels

[0046] category Substrate Number Plating solution number Yield strength, MPa Tensile strength, MPa Elongation, % Example 1 A 1 509 639 18.3 Example 2 B 1 524 678 19.4 Example 3 C 1 535 710 20.0 Example 4 D 1 529 707 19.8 Example 5 E 1 542 723 19.5 Example 6 E 2 539 718 19.2 Example 7 E 3 552 724 19.5 Example 8 E 4 545 713 19.1 Example 9 E 5 541 713 18.9 Example 10 E 6 555 731 20.1 Example 11 E 7 552 727 20.7

[0047] Cyclic corrosion tests were conducted on each sample according to GB / T 24195-2009 "Corrosion of Metals and Alloys - Cyclic Accelerated Corrosion Tests under Acid Salt Spray, 'Dry' and 'Wet' Conditions", with hot-dip galvanized ordinary steel (GI) used as a control. The results are as follows: Figure 1 As shown. The base material composition of hot-dip galvanized (GI) ordinary steel is: C: 0.02-0.055%, Si: 0-0.04%, Mn: 0.15-0.25%, P: 0-0.02%, S: 0-0.02%, S.Al: 0.015-0.05%, with the balance being Fe and unavoidable impurities; the plating solution composition is: Al: 0.25-0.3%, with the balance being Zn and unavoidable impurities.

[0048] from Figure 1 As can be seen from the above, the high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel for photovoltaic brackets in coastal mudflats prepared in Examples 5-11 of the present invention has a corrosion resistance that is much higher than that of ordinary hot-dip galvanized steel, and the sample in Example 11 has the best corrosion resistance.

Claims

1. A high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel, characterized in that: This high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel comprises a substrate and a coating adhered to the surface of the substrate. The substrate has the following mass percentage composition: C: The high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel is prepared by the following steps: 0.03%–0.06% Al, 0.20%–0.40% Si, 1.50%–2.00% Mn, P≤0.010%, S≤0.005%, Nb: 0.02%–0.04%, Ti: 0.03%–0.06%, with the balance being Fe and unavoidable impurities; the coating composition by mass percentage is: Al: 6.0%–15.0%, Mg: 1.0%–5.0%, Si: 0.1%–1.6%, Sn: 0%–0.2%, with the balance being Zn and unavoidable impurities; the preparation method of this high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel includes the following steps: firstly, high-strength, thin-gauge cold-rolled steel is produced using a hot-rolled thin slab continuous casting and rolling (CSP) process. The raw materials are then subjected to hot-dip galvanizing treatment. The specific process of the continuous casting and rolling (CSP) process includes: refining → thin slab continuous casting → soaking furnace → rough rolling → finish rolling → laminar flow cooling → coiling. The initial rolling temperature of the finish rolling is controlled at 950-850℃, the final rolling temperature is controlled at 750-820℃, and laminar flow cooling is carried out to 100-300℃ at a cooling rate of 20-35℃ / s. The specific process of hot-dip galvanizing is as follows: pickling of CSP cold-rolled raw materials → annealing → hot-dip galvanizing → coiling. During the hot-dip galvanizing stage, the strip steel is heated to 600-700℃ for 50-120s, and then cooled to a temperature 10-30℃ higher than the galvanizing bath temperature at a cooling rate of 40-80℃ / s. The galvanizing bath temperature is controlled at 500-540℃.

2. The high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel as described in claim 1, characterized in that: The coating has the following mass percentage composition: Al: 8.0%–12.0%, Mg: 2.0%–4.0%, Si: 0.2%–0.4%, Sn: 0.05%–0.15%, with the balance being Zn and unavoidable impurities, and 1 / 4 < Mg / Al < 1 / 2.

3. The high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel as described in claim 1, characterized in that: The high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel has a yield strength ≥500MPa, a tensile strength of 600~760MPa, an elongation ≥18%, and a thickness of 0.5~2mm.

4. The application of the high-strength, high-corrosion-resistant zinc-aluminum-magnesium steel described in any one of claims 1-3 in photovoltaic brackets for coastal mudflats.

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