A weathering steel plate and its manufacturing method

Abstract

This application relates to the field of medium and heavy plate manufacturing technology, and in particular to a weathering steel plate and its preparation method, to solve the problems of high production cost, low weathering index, and poor performance and weldability of ordinary weathering steel. The technical solution provided by this application to solve the above-mentioned technical problems is as follows: the chemical composition of the designed steel plate includes: 0.06 wt% ≤ C ≤ 0.09 wt%, 0.3 wt% ≤ Si ≤ 0.40 wt%, 0.9 wt% ≤ Mn ≤ 1.0 wt%, 0.02 wt% ≤ Alt ≤ 0.05 wt%, 0.010 wt% ≤ Nb ≤ 0.020 wt%, 0.025 wt% ≤ Ti ≤ 0.035 wt%, 0.03 wt% ≤ Ni ≤ 0.07 wt%, 0.55 wt% ≤ Cr ≤ 0.65 wt%, 0.30 wt% ≤ Cu ≤ 0.40 wt%, 0.075 wt% ≤ P ≤ 0.095 wt%, S < 0.002 wt%, Fe. The weathering steel manufactured under the composition and process conditions designed in this application has a high weathering index, high strength, low yield strength ratio, good low-temperature toughness and weldability, realizing the low-cost production of high weathering index high performance weathering steel.

Description

Technical Field

[0001] This application relates to the field of medium and heavy plate manufacturing technology, and in particular to a weathering steel plate and its manufacturing method. Background Technology

[0002] Atmospheric corrosion is the most significant form of loss for steel materials. To mitigate corrosion, methods such as painting or spraying are commonly used, which are costly and pollute the environment. Weathering steel, by adding weathering elements such as Ni, Cr, and Cu and undergoing surface rust stabilization treatment, forms a dense and stable rust layer on its surface, achieving rust prevention through rust itself. Its atmospheric corrosion resistance is improved by 2-8 times, significantly reducing painting and maintenance costs. Therefore, weathering steel is widely used in rail transportation, containers, steel structure buildings, and other fields.

[0003] Ordinary weathering steel has a high yield strength ratio but low strength, making it unsuitable for manufacturing large structural components. In addition, to meet corrosion resistance requirements, ordinary weathering steel requires the addition of a large amount of alloying elements such as Ni, Cr, and Cu, resulting in a low weathering index, high cost, and poor weldability. Summary of the Invention

[0004] This application provides a weathering steel plate and a method for manufacturing the same, in order to solve the problems of high production cost, low weathering index, and poor performance and weldability of ordinary weathering steel.

[0005] In a first aspect, this application provides a weathering steel plate, wherein the chemical composition of the steel includes:

[0006] 0.06 wt% ≤ C ≤ 0.09 wt%, 0.3 wt% ≤ Si ≤ 0.40 wt%, 0.9 wt% ≤ Mn ≤ 1.0 wt%, 0.02 wt% ≤ Alt ≤ 0.05 wt%, 0.010 wt% ≤ Nb ≤ 0.020 wt%, 0.025 wt% ≤ Ti ≤ 0.035 wt%, 0.03 wt% ≤ Ni ≤ 0.07 wt%, 0.55 wt% ≤ Cr ≤ 0.65 wt%, 0.30 wt% ≤ Cu ≤ 0.40 wt%, 0.075 wt% ≤ P ≤ 0.095 wt%, S < 0.002 wt%, Fe.

[0007] Optionally, the metallographic structure of the steel is ferrite and granular bainite.

[0008] Optionally, the ferrite content is 60%-80% by volume.

[0009] Optionally, the average diameter of the ferrite grains is ≤20μm.

[0010] Optionally, the performance parameters of the weathering steel plate satisfy at least one of the following I-VIII:

[0011] I. Carbon Equivalent (CEV) ≤ 0.40

[0012] II. Crack sensitivity index Pcm ≤ 0.20

[0013] III. Weather resistance index I ≥ 7.60,

[0014] IV. Yield strength ≥ 460 MPa

[0015] V. Tensile strength ≥ 560 MPa

[0016] VI. Yield-to-tensile strength ratio ≤ 0.85

[0017] VII. Impact energy at -40℃ ≥120J

[0018] VIII. Elongation after fracture ≥26%.

[0019] Secondly, this application provides a method for preparing weathering steel plate to achieve the preparation of weathering steel plate as described in any embodiment of the first aspect, the preparation method comprising:

[0020] Under the condition of center segregation of the billet, molten steel containing the aforementioned chemical composition is continuously cast to obtain a billet;

[0021] The billet is heated to a set temperature and a set heating time.

[0022] Under a set rolling temperature and a set pass reduction rate, the heated billet is subjected to a first-stage rolling process to obtain an intermediate billet with a set thickness to be heated.

[0023] The intermediate billet is subjected to a second-stage rolling process at a set initial rolling temperature and a set final rolling temperature to obtain a steel plate;

[0024] The steel plate is cooled at a set cooling rate and a set final cooling temperature to obtain a weathering steel plate.

[0025] Optionally, the heating temperature is 1170℃-1210℃, and the heating time is 200min-500min.

[0026] Optionally, the set center segregation of the billet is lower than Class C 1.0, and the set thickness to be heated is more than 3 times the thickness of the finished steel plate.

[0027] Optionally, the set rolling temperature is ≥950℃, and the set pass reduction rate is ≥15%.

[0028] Optionally, the set initial rolling temperature is 830℃-930℃, the set final rolling temperature is 790℃-830℃, the set cooling rate is 30℃ / s-50℃ / s, and the set final cooling temperature is 560℃-630℃.

[0029] The technical solutions provided in this application have the following advantages compared with the prior art:

[0030] The technical solution provided in this application significantly improves the weathering index of steel plates by adding a large amount of phosphorus (P) to their chemical composition. By controlling the carbon (C) content to ≤0.09% by weight, the steel plates are guaranteed to have good low-temperature toughness and weldability, compensating for the decrease in toughness caused by the increase in P content. Adding appropriate amounts of Cu and Cr elements improves both the weathering index and the performance of the steel plates. Adding trace amounts of Ni elements significantly reduces the cost of weathering steel while controlling the casting cracks that may be caused by Cu precipitation. Adding a large amount of Ti elements suppresses austenite coarsening during high-temperature heating. The weathering steel manufactured by this application with the above-designed composition has the characteristics of low production cost, high weathering index, excellent steel plate performance, and good weldability. It realizes the low-cost production of high-weathering-index, high-performance weathering steel, significantly improving economic and social benefits. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a rolling schedule diagram for a 10mm thick steel plate provided in Embodiment 1 of this application;

[0034] Figure 2 The cross-sectional microstructure of the 10mm thick steel plate provided in Embodiment 1 of this application;

[0035] Figure 3 This is a rolling schedule diagram for a 16mm thick steel plate provided in Embodiment 2 of this application;

[0036] Figure 4 The cross-sectional microstructure of the 16mm thick steel plate provided in Embodiment 2 of this application;

[0037] Figure 5 This is a rolling schedule diagram for a 20mm thick steel plate provided in Embodiment 3 of this application;

[0038] Figure 6 The cross-sectional microstructure of the 20mm thick steel plate provided in Embodiment 3 of this application.

[0039] Figure 7 A flowchart illustrating a method for preparing weathering steel plate provided in this application. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0041] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0042] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has 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., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0043] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the orientation shown in the accompanying drawings. Furthermore, in the description of this application, the terms "comprising" and "including" mean "including but not limited to".

[0044] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any actual relationship or order between these entities or operations. In this document, "and / or" describes the association between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0045] In a first aspect, this application provides a high-performance weathering steel plate, wherein the chemical composition of the steel includes:

[0046] 0.06 wt% ≤ C ≤ 0.09 wt%, 0.3 wt% ≤ Si ≤ 0.40 wt%, 0.9 wt% ≤ Mn ≤ 1.0 wt%, 0.02 wt% ≤ Alt ≤ 0.05 wt%, 0.010 wt% ≤ Nb ≤ 0.020 wt%, 0.025 wt% ≤ Ti ≤ 0.035 wt%, 0.03 wt% ≤ Ni ≤ 0.07 wt%, 0.55 wt% ≤ Cr ≤ 0.65 wt%, 0.30 wt% ≤ Cu ≤ 0.40 wt%, 0.075 wt% ≤ P ≤ 0.095 wt%, S < 0.002 wt%, Fe.

[0047] In some embodiments, the metallographic structure of the steel is ferrite and granular bainite.

[0048] In this embodiment, the steel plate has a dual-phase structure of ferrite and granular bainite. Ferrite has low strength, good plasticity and toughness. During plastic deformation, the soft phase ferrite with lower strength yields first, while the granular bainite with fine MA increases the tensile strength during subsequent deformation, thereby significantly reducing the yield strength ratio. Therefore, the weathering steel prepared in this application has a low yield strength ratio, good low-temperature toughness and plasticity.

[0049] In some embodiments, the ferrite content is 60%-80% by volume.

[0050] In this embodiment, controlling the ferrite ratio ensures that the steel plate has a low yield strength ratio, good low-temperature toughness and plasticity, and avoids low strength due to excessive ferrite content.

[0051] In some embodiments, the average diameter of the ferrite grains is ≤20 μm.

[0052] In this embodiment, fine ferrite grains are obtained, giving the steel plate high strength and good low-temperature toughness.

[0053] In some embodiments, the performance parameters of the weathering steel plate satisfy at least one of the following I-VIII:

[0054] I. Carbon Equivalent (CEV) ≤ 0.40

[0055] II. Crack sensitivity index Pcm ≤ 0.20

[0056] III. Weather resistance index I ≥ 7.60,

[0057] IV. Yield strength ≥ 460 MPa

[0058] V. Tensile strength ≥ 560 MPa

[0059] VI. Yield-to-tensile strength ratio ≤ 0.85

[0060] VII. Impact energy at -40℃ ≥120J

[0061] VIII. Elongation after fracture ≥26%.

[0062] In this embodiment, the low carbon equivalent and crack sensitivity index ensure that the steel plate has good weldability, the high weather resistance index makes the steel plate more resistant to atmospheric corrosion, and the low yield strength ratio, high strength, good low temperature toughness and elongation after fracture can improve the safety of the steel structure.

[0063] In this embodiment, carbon equivalent refers to converting the influence of various alloying elements in steel on the actual carbon content at the eutectic point into an increase or decrease in carbon. It is generally believed that the lower the carbon equivalent, the better the weldability.

[0064] In this embodiment, the cold crack sensitivity index Pcm is a method to indirectly judge the weldability of steel based on its chemical composition, mainly determining the steel's tendency to cold crack. The higher the cold crack sensitivity index, the greater the tendency of the steel to crack during welding, and the worse its weldability.

[0065] In this embodiment, steel with a weathering index of 6.0 or higher is generally referred to as weathering steel; the higher the index, the better the corrosion resistance of the steel. The weathering index I is defined as:

[0066] I=26.01(%Cu)+3.88(%Ni)+1.20(%Cr)+1.49(%Si)+17.28(%P)-7.29(%Cu)(%Ni)-9.10(%Ni)(%P)-33.39(%Cu) 2 .

[0067] In this embodiment, yield strength is the yield limit of a metallic material when it undergoes yielding, that is, the stress that resists a small amount of plastic deformation. For metallic materials that do not exhibit obvious yielding, the stress value that produces 0.2% residual deformation is defined as its yield limit, which is called conditional yield limit or yield strength.

[0068] In this embodiment, tensile strength is the critical value at which a metal transitions from uniform plastic deformation to localized concentrated plastic deformation, and it is also the maximum load-bearing capacity of a metal under static tensile conditions. Tensile strength characterizes the resistance of a material to maximum uniform plastic deformation. Before the tensile specimen is subjected to the maximum tensile stress, the deformation is uniform, but after exceeding this stress, the metal begins to exhibit necking, i.e., concentrated deformation occurs. For brittle materials with no (or very little) uniform plastic deformation, it reflects the material's fracture resistance.

[0069] In this embodiment, the yield strength ratio refers to the ratio of a material's yield point (yield strength) to its tensile strength. A yield strength ratio that is too high leads to brittle failure, which is strictly prohibited in civil engineering because failure occurs without noticeable deformation, making it difficult to prevent. Under seismic forces, steel first reaches its yield strength, and the strength continues to develop, causing structural deformation. This deformation is visible to the naked eye, indicating an early warning sign of structural failure, allowing for early detection and prevention. Therefore, a lower yield strength ratio results in a greater safety margin for the material.

[0070] In this embodiment, impact energy is an indicator of material toughness, which is the material's ability to absorb plastic deformation energy and fracture energy under impact load.

[0071] In this embodiment, elongation after fracture refers to the percentage of the length the test bar elongates relative to its original length when the metal material breaks under external force (tension).

[0072] Secondly, this application provides a method for preparing weathering steel plate to achieve the preparation of weathering steel plate as described in any embodiment of the first aspect, the preparation method comprising:

[0073] Under the condition of center segregation of the billet, molten steel containing the aforementioned chemical composition is continuously cast to obtain a billet;

[0074] The billet is heated to a set temperature and a set heating time.

[0075] Under a set rolling temperature and a set pass reduction rate, the heated billet is subjected to a first-stage rolling process to obtain an intermediate billet with a set thickness to be heated.

[0076] The intermediate billet is subjected to a second-stage rolling process at a set initial rolling temperature and a set final rolling temperature to obtain a steel plate;

[0077] The steel plate is cooled at a set cooling rate and a set final cooling temperature to obtain a weathering steel plate.

[0078] In this embodiment, the heating temperature is 1170℃-1210℃ and the heating time is 200min-500min.

[0079] In this embodiment, the billet is fully heated to reduce the resistance to rolling deformation and ensure that the alloying elements are fully dissolved. At the same time, the austenite structure is not too coarse. If the heating temperature is too low or the time is too short, the alloying elements will not be fully dissolved, resulting in poor steel plate performance. If the heating temperature is too high or the time is too long, the billet structure will be coarse, affecting the low-temperature impact toughness.

[0080] In some embodiments, the set billet center segregation is lower than Class C 1.0, and the set waiting thickness is more than 3 times the thickness of the finished steel plate.

[0081] In this embodiment, the thickness to be heated is more than three times the thickness of the finished steel plate in order to ensure sufficient recrystallization of austenite, ensure uniform microstructure, increase the cumulative deformation in the non-recrystallized area, refine the microstructure of the steel plate, and improve the performance of the steel plate.

[0082] In some embodiments, the set rolling temperature is ≥950°C, and the set pass reduction rate is ≥15%.

[0083] In some embodiments, the set initial rolling temperature is 830℃-930℃, the set final rolling temperature is 790℃-830℃, the set cooling rate is 30℃ / s-50℃ / s, and the set final cooling temperature is 560℃-630℃.

[0084] In this embodiment, the initial rolling temperature is set at 830℃-930℃ to avoid rolling in the mixed crystal zone; the final rolling temperature is set at 790℃-830℃ to refine the steel plate microstructure using low-temperature rolling; the cooling rate is set at 30℃ / s-50℃ / s to increase the phase transformation driving force and refine the steel plate microstructure using a high cooling rate; and the final cooling temperature is set at 560℃-630℃ to control the morphology of ferrite and granular bainite.

[0085] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0086] Example 1

[0087] The chemical composition of the weathering steel plate prepared in this embodiment is as follows: C: 0.079 wt%, Si: 0.35 wt%, Mn: 0.94 wt%, Alt: 0.028 wt%, Nb: 0.014 wt%, Ti: 0.030 wt%, Ni: 0.06 wt%, Cr: 0.60 wt%, Cu: 0.32 wt%, P: 0.085 wt%, S: 0.0009 wt%, with the remainder being Fe and unavoidable elements. The preparation method of the weathering steel plate is as follows: Figure 7 As shown. With a center segregation of C-type 0.5 in the billet, molten steel containing the above chemical composition is continuously cast to obtain a billet. Subsequently, the billet is heated at a heating temperature of 1180℃ for 240 minutes. Then, a two-stage controlled rolling process is adopted using a double stand. The billet is rolled in the first stage at a rolling temperature above 980℃ and a maximum pass reduction rate of 27.32% to obtain an intermediate billet with a set thickness of 30mm. The intermediate billet is rolled in the second stage at an initial rolling temperature of 922℃ and a final rolling temperature of 816℃ to obtain a steel plate. Finally, the steel plate is cooled to 619℃ at a cooling rate of 48℃ / s to obtain a weathering steel plate. The prepared weathering steel plate has a CEV of 0.38, Pcm of 0.19, and I of 7.66. The slab dimensions are 200*2200*2700 mm, the plate dimensions are 10*3600*30100 mm, and the plate thickness is 10 mm. The performance parameters of the prepared weathering steel plate are shown in Table 1, and the rolling process diagram is shown below. Figure 1 As shown, the microstructure of the steel plate cross section is as follows Figure 2 As shown.

[0088] Example 2

[0089] The chemical composition of the weathering steel plate prepared in this embodiment is as follows: C: 0.072 wt%, Si: 0.37 wt%, Mn: 0.96 wt%, Alt: 0.032 wt%, Nb: 0.016 wt%, Ti: 0.032 wt%, Ni: 0.05 wt%, Cr: 0.62 wt%, Cu: 0.34 wt%, P: 0.089 wt%, S: 0.0014 wt%, with the remainder being Fe and unavoidable elements. The preparation method of the weathering steel plate is as follows: Figure 7 As shown. With a center segregation of C-type 0.5 in the billet, molten steel containing the above chemical composition was continuously cast to obtain a billet. Subsequently, the billet was heated at a heating temperature of 1197℃ for 271 minutes. Then, a two-stage controlled rolling process was adopted using a double stand. The billet was rolled in the first stage at a rolling temperature of 995℃ or higher and a maximum pass reduction rate of 20.56% to obtain an intermediate billet with a set thickness of 48mm. The intermediate billet was rolled in the second stage at an initial rolling temperature of 876℃ and a final rolling temperature of 815℃ to obtain a steel plate. Finally, the steel plate was cooled to 602℃ at a cooling rate of 37℃ / s to obtain a weathering steel plate. The prepared weathering steel plate has a CEV of 0.38, Pcm of 0.18, and I of 7.85. The slab dimensions are 200*1800*2900 mm, the plate dimensions are 16*3300*17900 mm, and the plate thickness is 16 mm. The performance parameters of the prepared weathering steel plate are shown in Table 2, and the rolling process diagram is shown below. Figure 3 As shown, the microstructure of the steel plate cross section is as follows Figure 4 As shown.

[0090] Example 3

[0091] The chemical composition of the weathering steel plate prepared in this embodiment is as follows: C wt%: 0.085 wt%, Si: 0.32 wt%, Mn: 0.92 wt%, Alt: 0.037 wt%, Nb: 0.018 wt%, Ti: 0.029 wt%, Ni: 0.06 wt%, Cr: 0.61 wt%, Cu: 0.38 wt%, P: 0.092 wt%, S: 0.0012 wt%, with the remainder being Fe and unavoidable elements. The preparation method of the weathering steel plate is as follows: Figure 7 As shown. With a center segregation of C-class 0.5 in the billet, molten steel containing the above chemical composition was continuously cast to obtain a billet. The billet was then heated at 1192℃ for 305 minutes. Following this, a two-stage controlled rolling process was employed, with a rolling temperature above 1020℃ and a maximum pass reduction of 21.28%. The heated billet underwent a first-stage rolling process to obtain an intermediate billet with a set thickness of 60mm. This intermediate billet underwent a second-stage rolling process at an initial rolling temperature of 854℃ and a final rolling temperature of 803℃ to obtain a steel plate. Finally, the steel plate was cooled to 567℃ at a cooling rate of 33℃ / s to obtain a weathering steel plate. The prepared weathering steel plate had a CEV of 0.39, Pcm of 0.19, and I of 7.88. The slab dimensions are 200*2200*3600 (mm), the steel plate dimensions are 20*3100*23200 (mm), and the steel plate thickness is 20mm. The performance parameters of the prepared weathering steel plate are shown in Table 3, and the steel plate rolling procedure diagram is shown below. Figure 5 As shown, the microstructure of the steel plate cross section is as follows Figure 6 As shown.

[0092] Relevant experimental and effect data:

[0093] Table 1

[0094]

[0095] Table 2

[0096]

[0097] Table 3

[0098]

[0099] In summary, the weathering steel prepared under the composition and process conditions designed in this application possesses high weathering index, high strength, low yield strength ratio, good low-temperature toughness, and weldability. This achieves low-cost production of high weathering index, high-performance weathering steel. The performance parameters of the prepared steel meet the following requirements: CEV≤0.40, Pcm≤0.20, I≥7.60, yield strength≥460MPa, tensile strength≥560MPa, yield strength ratio≤0.85, impact energy at -40℃≥120J, and elongation after fracture≥26%.

[0100] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A weathering resistant steel sheet, characterized by, The chemical composition of the steel is: 0.06 wt%≤C≤0.09 wt%, 0.3 wt%≤Si≤0.40 wt%, 0.9 wt%≤Mn≤1.0 wt%, 0.02 wt%≤Alt≤0.05 wt%, 0.010 wt%≤Nb≤0.020 wt%, 0.025 wt%≤Ti≤0.035 wt%, 0.03 wt%≤Ni≤0.07 wt%, 0.55 wt%≤Cr≤0.65 wt%, 0.30 wt%≤Cu≤0.40 wt%, 0.075 wt%≤P≤0.095 wt%, S<0.002 wt%, the balance being Fe; The microstructure of the steel is: ferrite and granular bainite; The content of the ferrite is 60 vol%-80 vol%; The average diameter of the grain of the ferrite is ≤20 μm; The performance parameters of the weathering steel plate meet at least one of the following I-VIII: I, carbon equivalent CEV≤0.40, II, crack sensitivity index Pcm≤0.20, III, weathering index I≥7.60, IV, yield strength≥460 MPa, V, tensile strength≥560 MPa, VI, yield strength ratio≤0.85, VII, impact energy at -40℃≥120 J, VIII, elongation after fracture≥26%.

2. A method for producing a weathering steel sheet, characterized by, The weathering steel plate of claim 1 is prepared by a method comprising: casting a molten steel containing the chemical composition to obtain a casting blank under a set center segregation of the casting blank; heating the casting blank under a set heating temperature and a set heating time; first stage rolling the heated casting blank under a set rolling temperature and a set pass reduction rate to obtain an intermediate blank with a set warm-up thickness; second stage rolling the intermediate blank under a set rough rolling temperature and a set finish rolling temperature to obtain a steel plate; cooling the steel plate under a set cooling speed and a set final cooling temperature to obtain a weathering steel plate.

3. The production method according to claim 2, characterized by, The heating temperature is 1170℃-1210℃, and the heating time is 200 min-500 min.

4. The production method according to claim 2, characterized by, The set center segregation of the casting blank is lower than C class 1.0, and the set warm-up thickness is more than 3 times the thickness of the finished steel plate.

5. The preparation method according to claim 2, characterized in that, The set rolling temperature is≥950℃, and the set pass reduction rate is≥15%.

6. The preparation method according to claim 2, characterized in that, The set rough rolling temperature is 830℃-930℃, the set finish rolling temperature is 790℃-830℃, the set cooling speed is 30℃ / s-50℃ / s, and the set final cooling temperature is 560℃-630℃.

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