A kind of weathering steel and its application and preparation method

Abstract

The present application relates to a weathering steel and its application and preparation method, wherein the chemical composition of the weathering steel includes: C, Si, Mn, Ni, Cr, Cu, Ti, P, S, Al, N, Fe and inevitable impurities; wherein, by mass fraction, the content of C is 0.02% to 0.05%, the content of Si is 0.40% to 0.60%, the content of Mn is 0.30% to 0.80%, the content of Ni is 0.10% to 0.30%, the content of Cr is 0.30% to 0.80%, the content of Cu is 0.20% to 0.80%, and the content of Ti is 0.40% to 0.60%. The weathering steel provided by the present application can be applied not only to industrial atmospheric environment, but also to high temperature and humid marine atmospheric environment.

Description

Technical Field

[0001] The present application relates to the technical field of steel preparation, and in particular to a weathering steel and its application and preparation method. Background Art

[0002] Weathering steel is widely used in railway, vehicle, bridge and construction industries. It protects the steel matrix by forming a protective rust layer and reduces corrosion losses caused by the atmospheric environment. my country's research on weathering steel began in the 1960s. In 1984, my country's atmospheric corrosion resistant steel standards (GB4171-84 and GB4172-84) were formulated, including three grades with high weather resistance: 09CuPCrNi-A, 09CuPCrNi-B, 09CuP and four grades of weathering steel for welding structures: 16CuCr, 1MnCuCr, 15MnCuCr, and 15MnCuCr-QT. It can be seen from the standard that precious alloy elements such as Cu, Cr, and Ni are mainly added to weathering steel to improve the weather resistance of steel.

[0003] However, in different atmospheric environments, especially the hot and humid marine climate, the service life of weathering steel needs to be further improved. Summary of the invention

[0004] The present application provides a weathering steel and its application and preparation method to solve the following technical problem: how to improve the marine atmospheric corrosion resistance of weathering steel.

[0005] In a first aspect, the present application provides a weathering steel, the chemical composition of which includes:

[0006] C, Si, Mn, Ni, Cr, Cu, Ti, P, S, Al, N and Fe and unavoidable impurities; among which, in terms of mass fraction,

[0007] The C content is 0.02% to 0.05%, the Si content is 0.40% to 0.60%, the Mn content is 0.30% to 0.80%, the Ni content is 0.10% to 0.30%, the Cr content is 0.30% to 0.80%, the Cu content is 0.20% to 0.80%, and the Ti content is 0.40% to 0.60%.

[0008] Optionally, the C content is 0.03% to 0.04%, the Si content is 0.45% to 0.55%, the Mn content is 0.43% to 0.75%, the Ni content is 0.15% to 0.18%, the Cr content is 0.40% to 0.80%, the Cu content is 0.24% to 0.25%, and the Ti content is 0.45% to 0.60%.

[0009] Optionally, the P content is ≤0.020%, the S content is ≤0.004%, the Al content is 0.01% to 0.05%, and the N content is 0.0035% to 0.006%.

[0010] Optionally, the weathering steel meets the following mechanical properties: yield strength of 650MPa to 690MPa, tensile strength of 770MPa to 790MPa, and elongation of 28% to 32%.

[0011] Optionally, based on weathering steel 09CuPCrNi, the relative corrosion rate of the weathering steel is below 0.3.

[0012] In a second aspect, the present application provides an application of the weathering steel described in any embodiment of the first aspect in an industrial atmospheric environment or a marine atmospheric environment.

[0013] In a third aspect, the present application provides a method for preparing the weathering steel according to any one of the embodiments of the first aspect, the method being implemented by a continuous casting and rolling method, the method comprising:

[0014] heating the continuous casting billet;

[0015] Rough rolling the heated continuous casting billet to obtain an intermediate billet;

[0016] The intermediate billet is subjected to induction heating, and then finish rolling, slow cooling and coiling are performed to obtain weathering steel; wherein,

[0017] The total deformation of the rough rolling is ≥85%, and the cooling rate of the slow cooling is <15°C / s.

[0018] Optionally, the heating temperature is ≥1100°C.

[0019] Optionally, the induction heating temperature is 1100°C to 1200°C.

[0020] Optionally, the outlet temperature of the rough rolling is 950°C to 1100°C.

[0021] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0022] The weathering steel provided in the embodiment of the present application has a C content of 0.02% to 0.05% and a Si content of 0.30% to 0.80%, which can achieve interstitial solid solution strengthening in the Fe lattice and substitutional solid solution strengthening of Mn and Fe atoms, thereby ensuring that the basic strength of the steel is about 400MPa, and utilizing the solid solution strengthening of corrosion-resistant alloying elements Si, Cu, Ni, Cr and Ti, the steel can achieve a tensile strength of about 750MPa; the Si content is 0.40% to 0.60%, which can increase the adhesion between the rust layer and the matrix and prevent the rust layer from peeling off, thereby improving the corrosion resistance of the steel; the Ni content is 0.10% to 0.30%, which can generate a Cu-Ni solid solution with a higher melting point, having the function of controlling The effect of reducing cracks in the ingot and improving corrosion resistance; at the same time, Ni can promote the formation of a stable and dense inner rust layer on the steel surface, improving the resistance to marine atmospheric corrosion; the Cr content is 0.30% to 0.80%, which can be enriched at the interface between the rust layer and the matrix, blocking the Cl element in the outer rust layer, inhibiting the further occurrence of corrosion, and improving the weather resistance of the steel; the Cu content is 0.20% to 0.80%, which can be enriched in the inner rust layer of weathering steel to reduce the acceleration of chloride ion corrosion on steel, and at the same time can improve the polarization resistance in the electrochemical process of steel corrosion, and further enhance the protection of the rust layer to the steel matrix; the Ti content is 0.40% to 0.60%, which can enrich Ti at the interface between the rust layer and the matrix, and promote the formation of a stable rust layer. In summary, the marine atmospheric corrosion resistance of weathering steel is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0025] Figure 1 A schematic diagram of a process for preparing weathering steel provided in an embodiment of the present application;

[0026] Figure 2 A microstructure diagram of a weathering steel provided in Example 1 of the present application;

[0027] Figure 3 A corrosion performance characterization diagram of a weathering steel provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0029] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0030] In this application, the terms "including", "comprising", etc. mean "including but not limited to".

[0031] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0032] In a first aspect, the present application provides a weathering steel, the chemical composition of which includes:

[0033] C, Si, Mn, Ni, Cr, Cu, Ti, P, S, Al, N and Fe and unavoidable impurities; among which, in terms of mass fraction,

[0034] The C content is 0.02% to 0.05%, the Si content is 0.40% to 0.60%, the Mn content is 0.30% to 0.80%, the Ni content is 0.10% to 0.30%, the Cr content is 0.30% to 0.80%, the Cu content is 0.20% to 0.80%, and the Ti content is 0.40% to 0.60%.

[0035] In some embodiments, the C content is 0.03% to 0.04%, the Si content is 0.45% to 0.55%, the Mn content is 0.43% to 0.75%, the Ni content is 0.15% to 0.18%, the Cr content is 0.40% to 0.80%, the Cu content is 0.24% to 0.25%, and the Ti content is 0.45% to 0.60%.

[0036] In the embodiment of the present application, the above C content and Mn content are limited; C is used for interstitial solid solution strengthening in the Fe lattice, and Mn is used for substitutional solid solution strengthening with Fe atoms to ensure that the basic strength of the steel is about 400MPa. By using the solid solution strengthening of corrosion-resistant alloying elements Si, Cu, Ni, Cr, and Ti, the tensile strength of the steel strip can reach about 750MPa. Exemplarily, the above C content can be 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, etc., and the above Mn content can be 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, etc.

[0037] The weather resistance of Ti is reflected in two aspects. First, when the content reaches a certain level, the Ti element is enriched at the interface between the rust layer and the matrix; second, it promotes the formation of a stable rust layer. The above-mentioned Ti content is limited to achieve the effect of significantly improving the weather resistance of steel; when the Ti content is too high, the weather resistance effect will be saturated, wasting costs; when the Ti content is too low, the weather resistance of steel will be significantly reduced. Exemplarily, the above-mentioned Ti content can be 0.40%, 0.43%, 0.45%, 0.48%, 0.50%, 0.53%, 0.55%, 0.58%, 0.60%, etc.

[0038] Si improves the corrosion resistance of steel by increasing the adhesion between the rust layer and the substrate and preventing the rust layer from peeling off. The above-mentioned Si content is limited to achieve the effect of significantly improving the weather resistance of steel; when the Si content is too high, it will strongly promote the segregation of Ti elements at the grain boundaries and deteriorate the mechanical properties of steel; when the Si content is too low, it will lead to a decrease in the adhesion of the rust layer and a significant decrease in the weather resistance of steel. Exemplarily, the above-mentioned Si content can be 0.40%, 0.43%, 0.45%, 0.48%, 0.50%, 0.53%, 0.55%, 0.58%, 0.60%, etc.

[0039] The enrichment of Cu in the rust layer inside weathering steel can reduce the accelerated corrosion of steel by chloride ions, and at the same time can increase the polarization resistance in the electrochemical process of steel corrosion, further enhancing the protection of the rust layer to the steel matrix. Limiting the above-mentioned Cu content can significantly improve the weather resistance of steel; when the Cu content is too high, the weather resistance effect will be saturated, wasting costs; when the Cu content is too low, the weather resistance of the steel cannot be effectively improved. Exemplarily, the above-mentioned Cu content can be 0.20%, 0.30%, 0.40%, 0.50%, 0.60%, 0.70%, 0.80%, etc.

[0040] During the production and heating process of Cu-containing steel, the surface Fe is selectively oxidized, and a low-melting-point Cu-rich phase is easily formed at the interface between the surface and the oxide layer. At a higher heating temperature, a liquid Cu phase is formed and penetrates along the austenite grain boundary, resulting in surface cracks. Adding Ni elements can generate Cu-Ni solid solutions with a higher melting point, which has the effect of controlling cracks in the ingot and improving corrosion resistance. At the same time, Ni is a key alloying element for improving the marine atmospheric corrosion resistance of steel plates, which promotes the formation of a stable and dense inner rust layer on the steel surface and improves the marine atmospheric corrosion resistance. In addition, Ni elements can increase the number of slip planes during the plastic deformation of the material and significantly improve the plastic toughness of the steel. Limiting the above-mentioned Ni content can significantly improve the weather resistance of the steel, inhibit Cu brittleness, and improve the plastic toughness of the steel. When the Ni content is too high, it will cause an increase in cost. When the Ni content is too low, rolling cracks will easily occur in the ingot, and the plastic toughness and weather resistance of the product will decrease. For example, the Ni content may be 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, etc.

[0041] The Cr element is enriched at the interface between the rust layer and the matrix, blocking the Cl element in the outer rust layer, inhibiting further corrosion and improving the weather resistance of the steel; the above Cr content is limited to achieve the effect of significantly improving the weather resistance of the steel; when the Cr content is too high, the rolling resistance will increase significantly, increasing the process cost; when the Cr content is too low, the weather resistance will decrease. For example, the Cr content can be 0.30%, 0.40%, 0.50%, 0.60%, 0.70%, 0.80%, etc.

[0042] Further, the C content may be 0.03% to 0.04%, the Si content may be 0.45% to 0.55%, the Mn content may be 0.43% to 0.75%, the Ni content may be 0.15% to 0.18%, the Cr content may be 0.60%, the Cu content may be 0.24% to 0.25%, and the Ti content may be 0.45% to 0.60%.

[0043] In some embodiments, the content of P is ≤0.020%, the content of S is ≤0.004%, the content of Al is 0.01% to 0.05%, and the content of N is 0.0035% to 0.006%.

[0044] In the embodiments of the present application, the P content can be 0.020%, 0.018%, 0.016%, etc., the S content can be 0.004%, 0.003%, 0.002%, etc., the Al content can be 0.05%, 0.04%, 0.03%, 0.02%, 0.01%, etc., and the N content can be 0.0035%, 0.0040%, 0.0045%, 0.0050%, 0.0055%, 0.006%, etc.

[0045] In some embodiments, the weathering steel meets the following mechanical properties: yield strength of 650MPa to 690MPa, tensile strength of 770MPa to 790MPa, and elongation of 28% to 32%.

[0046] In some embodiments, based on weathering steel 09CuPCrNi, the relative corrosion rate of the weathering steel is 0.3 or less.

[0047] In the embodiments of the present application, the above-mentioned weathering steel meets the following mechanical properties: yield strength of 650MPa~690MPa, tensile strength of 770MPa~790MPa, elongation of 28%~32%, and strength is higher than that of traditional weathering steel 09CuPCrNi; based on weathering steel 09CuPCrNi, the relative corrosion rate of the above-mentioned weathering steel is less than 0.3.

[0048] In a second aspect, the present application provides an application of the weathering steel described in any embodiment of the first aspect in an industrial atmospheric environment or a marine atmospheric environment.

[0049] In the embodiments of the present application, the content of precious alloy elements such as Cu and Ni is greatly reduced in the chemical composition of the weathering steel, and the weathering resistance of the steel is improved by significantly increasing the content of Si and Ti elements, so as to obtain a weathering steel with both economy and weather resistance. Compared with the traditional weathering steel 09CuPCrNi, the relative corrosion rate is below 0.3, which can not only be used in industrial atmospheric environment, but also can cope with high temperature and humid marine atmospheric environment.

[0050] In a third aspect, the present application provides a method for preparing the weathering steel according to any one of the embodiments of the first aspect, Figure 1 A schematic diagram of a method for preparing weathering steel provided in an embodiment of the present application; see Figure 1 , the method is implemented by continuous casting and rolling, and the method comprises:

[0051] S1, heating the continuous casting billet;

[0052] S2, rough rolling the heated continuous casting billet to obtain an intermediate billet;

[0053] S3. Induction heating the intermediate billet, followed by finish rolling, slow cooling and coiling to obtain weathering steel; wherein the total deformation of the rough rolling is ≥85%, and the cooling rate of the slow cooling is <15°C / s.

[0054] In the embodiment of the present application, the preparation method of the above-mentioned weathering steel is designed to adopt a short-process hot rolling production line and the MCCR equipment of the Shougang Jingtang production line. Due to the high content of Ti element, the supersaturated solid solution of Ti is easy to cause cracks in the ingot during the cooling process. Therefore, a continuous casting and rolling process is required. The total deformation of the rough rolling is limited, the deformation is concentrated in the high temperature stage, the austenite grains are fully refined, and the uniform distribution of the Ti element is ensured. The cooling rate of the above-mentioned slow cooling is limited to avoid the cooling rate being too fast, and the supersaturated solid solution of Ti causes the toughness of the steel to deteriorate. Exemplarily, the total deformation of the above-mentioned rough rolling can be 85%, 86%, 87%, 88%, 89%, etc., and the cooling rate of the above-mentioned slow cooling can be 14℃ / s, 13℃ / s, 12℃ / s, 11℃ / s, 10℃ / s, etc.

[0055] In some embodiments, the heating temperature is ≥ 1100°C.

[0056] In the embodiment of the present application, the heating temperature is limited to avoid excessive rolling resistance during rough rolling and ensure rolling stability. For example, the heating temperature may be 1100°C, 1150°C, 1200°C, etc.

[0057] In some embodiments, the induction heating temperature is 1100°C to 1200°C.

[0058] In the embodiment of the present application, the temperature of induction heating is limited to ensure the finishing temperature, reduce the finishing rolling resistance, and ensure rolling stability. For example, the temperature of the induction heating can be 1100°C, 1130°C, 1150°C, 1180°C, 1200°C, etc.

[0059] In some embodiments, the outlet temperature of the rough rolling is 950°C to 1100°C.

[0060] In the embodiment of the present application, the outlet temperature of the rough rolling is limited, which can reduce the induction heating time and energy consumption. For example, the outlet temperature of the rough rolling can be 950°C, 1000°C, 1050°C, 1100°C, etc.

[0061] Specifically, the preparation method of weathering steel comprises: (1) using short-process equipment, after steelmaking and continuous casting, the continuous casting billet directly enters a tunnel furnace, and the temperature of the tunnel furnace is ≥1100°C; (2) the total deformation of rough rolling is ≥85%, and descaling is performed in each pass; the outlet temperature of rough rolling is controlled at 950-1100°C; (3) the intermediate billet after rough rolling enters online induction heating, and the induction heating temperature is controlled at 1100-1200°C; (4) after induction heating, the slab enters finishing rolling, and the strip is slowly cooled after finishing rolling, and the cooling rate is less than 15°C / s, and then coiled;

[0062] The preparation method of the weathering steel is implemented based on the above-mentioned weathering steel. The specific chemical composition of the weathering steel can refer to the above-mentioned embodiment. Since the preparation method of the weathering steel adopts part or all of the technical solutions of the above-mentioned embodiment, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiment, which will not be repeated here one by one.

[0063] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0064] The present application provides a weathering steel, and the chemical composition thereof is shown in Table 1.

[0065] Table 1 Chemical composition of weathering steel (wt%), the rest is Fe and unavoidable impurities

[0066]

[0067] Example 1

[0068] A method for preparing weathering steel comprises: casting smelted molten steel having the components described in Example 1 in Table 1 into a billet, the billet enters a tunnel furnace, controls the temperature of the tunnel furnace to be 1180°C, and then performs rolling. The rough rolling outlet temperature is 1100°C, the rough rolling is performed for 3 passes, and the total deformation amount in the rough rolling stage is 90%; after the rough rolling, the intermediate billet enters an induction heating device, and the induction heating temperature is controlled at 1200°C; then the billet enters the finishing rolling, the finishing rolling is performed for 5 passes, and the total deformation amount in the finishing rolling stage is 10%; after the strip is rolled, the strip enters air cooling, the air cooling rate is 10°C / s, and the strip is directly coiled to obtain the weathering steel.

[0069] Example 2

[0070] A method for preparing weathering steel comprises: casting smelted molten steel having the components described in Example 2 in Table 1 into a billet, the billet enters a tunnel furnace, controls the temperature of the tunnel furnace to be 1150°C, and then performs rolling. The rough rolling outlet temperature is 1080°C, the rough rolling is performed for 3 passes, and the total deformation amount in the rough rolling stage is 88%; after the rough rolling, the intermediate billet enters an induction heating device, and the induction heating temperature is controlled at 1180°C; then the billet enters the finishing rolling, and the finishing rolling is performed for 5 passes, and the total deformation amount in the finishing rolling stage is 12%; after the strip is rolled, the strip enters air cooling, and the air cooling rate is 8°C / s, and the strip is directly coiled to obtain the weathering steel.

[0071] Example 3

[0072] A method for preparing weathering steel comprises: casting smelted molten steel having the components described in Example 3 in Table 1 into a billet, the billet enters a tunnel furnace, controls the temperature of the tunnel furnace to be 1100°C, and then performs rolling. The rough rolling outlet temperature is 1050°C, the rough rolling is performed for 3 passes, and the total deformation amount in the rough rolling stage is 85%; after the rough rolling, the intermediate billet enters an induction heating device, and the induction heating temperature is controlled at 1160°C; then the billet enters the finishing rolling, and the finishing rolling is performed for 5 passes, and the total deformation amount in the finishing rolling stage is 15%; after the strip is rolled, the strip enters air cooling, and the air cooling rate is 6°C / s, and the strip is directly coiled to obtain the weathering steel.

[0073] Example 4

[0074] A method for preparing weathering steel comprises: casting smelted molten steel having the components described in Example 4 in Table 1 into a billet, the billet enters a tunnel furnace, controls the temperature of the tunnel furnace to be 1100°C, and then performs rolling. The rough rolling outlet temperature is 1050°C, the rough rolling is performed for 3 passes, and the total deformation amount in the rough rolling stage is 80%; after the rough rolling, the intermediate billet enters an induction heating device, and the induction heating temperature is controlled at 1150°C; then enters the finishing rolling, the finishing rolling is performed for 5 passes, and the total deformation amount in the finishing rolling stage is 20%; after the strip steel is rolled, it enters air cooling, the air cooling rate is 8°C / s, and it is directly coiled to obtain the weathering steel.

[0075] Example 5

[0076] A method for preparing weathering steel comprises: casting smelted molten steel having the components described in Example 5 in Table 1 into a billet, the billet enters a tunnel furnace, controls the temperature of the tunnel furnace to be 1100°C, and then performs rolling. The rough rolling outlet temperature is 1050°C, the rough rolling is performed for 3 passes, and the total deformation amount in the rough rolling stage is 89%; after the rough rolling, the intermediate billet enters an induction heating device, and the induction heating temperature is controlled at 1180°C; then the billet enters the finishing rolling, and the finishing rolling is performed for 5 passes, and the total deformation amount in the finishing rolling stage is 11%; after the strip steel is rolled, the strip enters air cooling, and the air cooling rate is 9°C / s, and the strip is directly coiled to obtain the weathering steel.

[0077] Comparative Example 1

[0078] A method for preparing weathering steel comprises: casting smelted molten steel having the components described in comparative example 1 in Table 1 into a billet, the billet enters a tunnel furnace, controls the temperature of the tunnel furnace to be 1180°C, and then performs rolling. The rough rolling outlet temperature is 1100°C, the rough rolling is performed for 3 passes, and the total deformation amount in the rough rolling stage is 90%; after the rough rolling, the intermediate billet enters an induction heating device, and the induction heating temperature is controlled at 1200°C; then the billet enters the finishing rolling, the finishing rolling is performed for 5 passes, and the total deformation amount in the finishing rolling stage is 10%; after the strip is rolled, the strip enters air cooling, the air cooling rate is 10°C / s, and the strip is directly coiled to obtain the weathering steel.

[0079] Comparative Example 2

[0080] A method for preparing weathering steel comprises: casting smelted molten steel having the components described in comparative example 2 in Table 1 into a billet, the billet enters a tunnel furnace, controls the temperature of the tunnel furnace to be 1180°C, and then performs rolling. The rough rolling outlet temperature is 1100°C, the rough rolling is performed for 3 passes, and the total deformation amount in the rough rolling stage is 90%; after the rough rolling, the intermediate billet enters an induction heating device, and the induction heating temperature is controlled at 1200°C; then the billet enters the finishing rolling, the finishing rolling is performed for 5 passes, and the total deformation amount in the finishing rolling stage is 10%; after the strip is rolled, the strip enters air cooling, the air cooling rate is 10°C / s, and the strip is directly coiled to obtain the weathering steel.

[0081] The mechanical properties of the weathering steels of Examples 1 to 5 and Comparative Examples 1 to 2 were tested. Please see Table 2 for the test results.

[0082] Table 2 Mechanical properties of weathering steel

[0083] Serial number Thickness(mm) Rp0.2(MPa) Rm(MPa) A，％ Example 1 1.6 686 782 28 Example 2 1.8 661 775 28 Example 3 2.0 658 770 32 Example 4 2.2 630 712 35 Example 5 2.2 731 820 26 Comparative Example 1 (09CuPCrNi) 6 360 520 36 Comparative Example 2 4 320 470 40

[0084] The method for testing the corrosion performance of weathering steel includes: the experiment is carried out in accordance with TB / T 2375-53, the experimental medium is a solution of 0.1% NaCl+0.05% Na2SO4+0.05% CaCl2 (mass fraction), simulating the marine atmospheric environment. The experimental temperature is controlled at (45±2)℃, and the humidity is controlled at (70±5)%. One cycle is 60min, including 12min of immersion and 48min of drying. The duration of the entire experiment is 505 hours, and samples are taken after 50 hours, 120 hours, 220 hours, 310 hours, and 505 hours respectively during the experiment. Please refer to the corrosion performance evaluation results of weathering steel shown in Table 3 for details.

[0085] Table 3 Corrosion performance evaluation results of weathering steel (based on relative corrosion rate of comparative example 1 (09CuPCrNi))

[0086] Serial number Relative corrosion rate based on comparative example 1 (09CuPCrNi) Example 1 0.20 Example 2 0.20 Example 3 0.20 Example 4 0.30 Example 5 0.17 Comparative Example 1 (09CuPCrNi) 1 Comparative Example 2 1.2

[0087] It can be seen from the data in Table 2 that the hot-rolled low-cost weathering steel provided in the embodiment of the present application has a yield strength range of 630-690 MPa, a tensile strength of 770-820 MPa, an elongation of 28%-35%, and a strength higher than that of traditional weathering steel 09CuPCrNi. Figure 2 A microstructure diagram of a weathering steel provided in Example 1 of the present application; see Figure 2 The microstructure is a single polygonal ferrite, which shows that the alloy elements are fully dissolved, which inhibits the pearlite phase transformation and improves the strength of the steel. The single ferrite structure ensures high elongation. Figure 3 A corrosion performance curve of a weathering steel provided in the embodiment of the present application; it can be clearly seen that the corrosion rates of Examples 1 to 3 are much lower than the corrosion rate of the weathering steel in Comparative Example 1, and combined with Tables 2 and 3, it is shown that the weathering steel provided in the embodiment of the present application has both excellent mechanical properties and weather resistance. Compared with Comparative Example 1 (traditional weathering steel 09CuPCrNi), the relative corrosion rate is below 0.3, which can not only be used in industrial atmospheric environments, but also cope with high temperature and humid marine atmospheric environments. The analysis of Comparative Example 2 and Example 1 is that the content of Ti is not within the scope of the embodiments of the present application, resulting in an increase in the relative corrosion rate and corrosion rate based on Comparative Example 2, and the Ti content is not enough to enrich the degree at the corrosion interface and fail to reach the effective content for protecting the steel matrix.

[0088] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A weathering steel, characterized in that: The chemical composition of the weathering steel includes: C, Si, Mn, Ni, Cr, Cu, Ti, P, S, Al, N and Fe and unavoidable impurities; among which, in terms of mass fraction, The C content is 0.02% to 0.05%, the Si content is 0.40% to 0.60%, the Mn content is 0.30% to 0.80%, the Ni content is 0.10% to 0.30%, the Cr content is 0.30% to 0.80%, the Cu content is 0.20% to 0.80%, and the Ti content is 0.40% to 0.60%.

2. The weathering steel according to claim 1, characterized in that: The C content is 0.03% to 0.04%, the Si content is 0.45% to 0.55%, the Mn content is 0.43% to 0.75%, the Ni content is 0.15% to 0.18%, the Cr content is 0.40% to 0.80%, the Cu content is 0.24% to 0.25%, and the Ti content is 0.45% to 0.60%.

3. The weathering steel according to claim 1, characterized in that: The content of P is ≤0.020%, the content of S is ≤0.004%, the content of Al is 0.01% to 0.05%, and the content of N is 0.0035% to 0.006%.

4. The weathering steel according to any one of claims 1 to 3, characterized in that: The weathering steel meets the following mechanical properties: yield strength of 650MPa to 690MPa, tensile strength of 770MPa to 790MPa, and elongation of 28% to 32%.

5. The weathering steel according to claim 4, characterized in that: Based on weathering steel 09CuPCrNi, the relative corrosion rate of the weathering steel is less than 0.

3.

6. Use of the weathering steel according to any one of claims 1 to 5 in an industrial atmosphere environment or a marine atmosphere environment.

7. A method for preparing weathering steel according to any one of claims 1 to 5, characterized in that: The method is implemented by a continuous casting and rolling method, and the method comprises: heating the continuous casting billet; Rough rolling the heated continuous casting billet to obtain an intermediate billet; The intermediate billet is induction heated, and then finish rolled, slowly cooled and coiled to obtain weathering steel; wherein the total deformation of the rough rolling is ≥85%, and the cooling rate of the slow cooling is <15°C / s.

8. The method according to claim 7, characterized in that The heating temperature is ≥1100°C.

9. The method according to claim 7, characterized in that: The induction heating temperature is 1100°C to 1200°C.

10. The method according to claim 7, characterized in that The outlet temperature of the rough rolling is 950°C to 1100°C.

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