1000MPa-grade hydroelectric steel with weather resistance not larger than 45mm as well as preparation method and application of 1000MPa-grade hydroelectric steel

Abstract

The invention discloses 1000MPa-grade hydroelectric steel with weather resistance not larger than 45mm as well as a preparation method and application of the 1000MPa-grade hydroelectric steel, and belongs to the technical field of wide and thick steel plate production. The hydroelectric steel is prepared from the following components in percentage by mass: 0.07 to 0.10 percent of C, 0.25 to 0.35 percent of Si, 0.65 to 0.85 percent of Mn, 0.005 to 0.010 percent of P, less than or equal to 0.005 percent of S, 0.020 to 0.050 percent of Alt, 0.020 to 0.030 percent of Nb, 0.030 to 0.045 percent of V, 0.012 to 0.020 percent of Ti, 0.70 to 1.20 percent of Ni, 1.60 to 1.90 percent of Cr, 0.20 to 0.30 percent of Cu, 0.40 to 0.50 percent of Mo and the balance of Fe and inevitable impurities. The hydroelectric steel plate is good in obdurability matching, meets the requirements for the strength and low-temperature toughness of 1000 MPa grade hydroelectric steel, and also has good weather resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of wide and thick steel plate production, and in particular relates to a 1000MPa grade hydroelectric steel with a thickness of no more than 45mm and weather resistance, and a preparation method and application thereof. Background Art

[0002] Under the new situation of accelerating the green and low-carbon transformation of energy, pumped storage is an urgent requirement for building a new power system with new energy as the main body. It is imperative to accelerate the development of pumped storage power stations. Pumped storage has a relatively broad prospect in the next few decades. In order to meet the material demand for pumped storage hydropower units to develop in the direction of large drop and ultra-high head, the development of 950MPa grade hydropower steel has begun at home and abroad. At the same time, since pumped storage hydropower stations are built in the wild and the working environment is humid and harsh, hydropower steel with corrosion resistance and weather resistance will greatly extend the life of the equipment.

[0003] Patent CN115747657A discloses a 950MPa grade high-strength steel for hydropower engineering and a preparation method. It is produced by using thick steel ingots to improve the rolling compression ratio. In the heat treatment process, multiple quenching is performed to ensure hardenability while refining the austenite grains, and tempering is used to improve the uniformity of the mechanical properties of the entire plate to produce 950MPa grade high-strength steel for hydropower engineering. However, the steel plate of this invention does not have weather resistance.

[0004] Patent CN114395731A discloses a low welding crack sensitivity arrest steel HY950CF for hydropower engineering, the thickness of the steel plate is 20-100mm, the structure is a tempered troostite structure with martensite orientation retained; the delivery state of the steel plate is online quenching + tempering treatment. Although the invention adopts a low-cost online quenching process and the thickness covers a thickness of less than 45mm, the steel plate does not have weather resistance and cannot meet the weather resistance requirements. Summary of the invention

[0005] In view of the above technical problems, the present invention proposes a 1000MPa grade hydroelectric steel with a thickness not greater than 45mm and weather resistance, as well as a preparation method and application thereof.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] One of the purposes of the present invention is to provide a 1000MPa grade hydroelectric steel with a thickness of no more than 45mm and weather resistance, comprising the following components in mass percentage: C (carbon): 0.07-0.10%, Si (silicon): 0.25-0.35%, Mn (manganese): 0.65-0.85%, P (phosphorus): 0.005-0.010%, S (sulfur) ≤0.005%, Alt (aluminum): 0.020-0 .050%, Nb (niobium): 0.020-0.030%, V (vanadium): 0.030-0.045%, Ti (titanium): 0.012-0.020%, Ni (nickel): 0.70-1.20%, Cr (chromium): 1.60-1.90%, Cu (copper): 0.20-0.30%, Mo (molybdenum): 0.40-0.50%, and the balance is Fe (iron) and inevitable impurities.

[0008] In order to ensure the high strength, high low temperature impact toughness and weather resistance of 1000MPa grade hydroelectric steel, the present invention adopts Nb, V, Ti, Cr, Ni, Mo, Cu and other elements for microalloying. Adding Cr, Ni and Mo elements can greatly improve the hardenability of hydroelectric steel plate, and keep its toughness at a high level through organizational adjustment. In addition, Cr can also improve the weather resistance of hydroelectric steel plate; a small amount of Cu element can not only strengthen the effect, but also improve the weather resistance of hydroelectric steel plate; microalloying elements Nb, V and Ti are crucial to the toughness, strength and weldability of hydroelectric steel plate, and promote the formation of various M (C, N) nano-precipitation phases in the heat treatment process; a small amount of P element can effectively improve the weather resistance of the steel plate.

[0009] Furthermore, the thickness of the hydropower steel is 6-45 mm.

[0010] Furthermore, the atmospheric corrosion resistance index I value of the hydroelectric steel is ≥8, and the calculation formula is I=26.01(Cu%)+3.88(Ni%)+1.20(Cr%)+1.49(Si%)+7.28(P%)-7.29(Cu%)(Ni%)-9.10(Ni%)(P%)-33.39(Cu%) 2 .

[0011] The second object of the present invention is to provide a method for preparing hydropower steel with a thickness of no more than 45 mm and a weather resistance of 1000 MPa, comprising the following steps: weighing components according to mass percentage to obtain a mixture, smelting and casting the mixture to obtain a steel billet; heating, rolling, rapid cooling after rolling and tempering the steel billet in sequence to obtain the hydropower steel.

[0012] Furthermore, during the smelting process, when the P content in the molten steel reaches 50-100 ppm, dephosphorization is stopped, and the P content of the finished hydropower steel product is controlled within the range of 0.005-0.010%.

[0013] Furthermore, a 200 mm specification continuous casting billet is used in the casting process.

[0014] Furthermore, the heating conditions are: heating temperature 1160-1180°C, heating rate ≤280°C / h, and total heating time 200-300min.

[0015] Furthermore, the specific operation steps of the rolling include: performing the first stage rolling at 1000-1080°C, and performing the second stage rolling at 880-930°C.

[0016] Furthermore, the condition of rapid cooling after rolling is: cooling rate 16-22°C / s.

[0017] Furthermore, the tempering treatment conditions are: tempering temperature 580-650°C, holding time 2.5-6min / mm.

[0018] The third object of the present invention is to provide a 1000MPa grade hydroelectric steel with a thickness not exceeding 45mm and weather resistance for use in the field of pumped storage.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects:

[0020] The hydroelectric steel prepared by the invention has a thickness of 6-45 mm, a room temperature yield strength of 915-937 MPa, a tensile strength of 1013-1045 MPa, a yield strength ratio of ≤0.94, an elongation of ≥26%, and a -60°C impact value of ≥142 J.

[0021] The strength and toughness of the hydropower steel plate prepared by the present invention are well matched. While meeting the strength and low-temperature toughness requirements of 1000MPa-grade hydropower steel, it also has good weather resistance. The weather resistance coefficient I value of the steel plate is maintained above 8, which greatly improves the weather resistance of the hydropower steel plate. After the salt spray corrosion test, the corrosion rate of the steel plate is much lower than the corrosion rate of ordinary low-alloy steel. The demand for weather-resistant high-strength hydropower steel in large-scale hydropower projects at home and abroad, especially high-head hydropower stations, can be met, and can be widely used in key parts such as pressure steel pipes of pumped-storage hydropower stations. DETAILED DESCRIPTION

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0024] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0025] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0026] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0027] The embodiment of the present invention discloses a preparation method of 1000MPa-grade hydropower steel with a thickness not greater than 45mm and weather resistance, comprising the following process steps: converter / electric furnace rough refining→LF refining→VD / RH vacuum treatment→continuous casting→slab heating→rolling→rapid cooling→tempering, and producing 1000MPa-grade hydropower steel with a thickness not greater than 45mm, a room temperature yield strength of 915-937MPa, a tensile strength of 1013-1045MPa, a yield strength ratio of ≤0.94, an elongation of ≥26%, an impact value of -60°C of ≥142J, and an atmospheric corrosion resistance index of the hydropower steel of 8 or more. Specifically, the process comprises the following steps: the hydropower steel comprises the following components in mass percentage: C: 0.07-0.10%, Si: 0.25-0.35%, Mn: 0.65-0.85%, P: 0.005-0.010%, S≤0.005%, Alt: 0.020-0.050%, Nb: 0.020-0.030%, V: 0.030-0.045%, Ti: 0.012-0.020%, Ni: 0.70-1.20%, Cr: 1.60-1.90%, Cu: 0.20-0.30%, Mo: 0.40-0.50%, and the balance is Fe and unavoidable impurities. The raw materials are weighed according to the mass percentage to obtain a mixed material, the mixed material is smelted and cast to obtain a steel billet; the steel billet is sequentially heated, rolled, rapidly cooled after rolling and tempered to obtain the hydropower steel.

[0028] The hydropower steel contains 0.07%, 0.08%, 0.10% or any range or sub-range therebetween of C;

[0029] The hydroelectric steel contains 0.25%, 0.30%, 0.35% Si or any range or sub-range therebetween;

[0030] The hydropower steel contains 0.65%, 0.75%, 0.85% or any range or sub-range therebetween of Mn;

[0031] The hydropower steel contains 0.006%, 0.008%, 0.010% or any range or sub-range therebetween of P;

[0032] The hydropower steel contains 0.004%, 0.005% or any range or sub-range therebetween of S;

[0033] The hydroelectric steel contains 0.020%, 0.030%, 0.050% or any range or sub-range therebetween of Alt;

[0034] The hydroelectric steel contains 0.020%, 0.025%, 0.030% or any range or sub-range therebetween of Nb;

[0035] The hydroelectric steel contains 0.030%, 0.045% or any range or sub-range therebetween of V;

[0036] The hydroelectric steel contains 0.012%, 0.016%, 0.020% or any range or sub-range therebetween of Ti;

[0037] The hydroelectric steel contains 0.70%, 0.90%, 1.20% or any range or sub-range therebetween of Ni;

[0038] The hydroelectric steel contains 1.60%, 1.75%, 1.90% or any range or sub-range therebetween of Cr;

[0039] The hydroelectric steel contains 0.20%, 0.25%, 0.30% or any range or sub-range therebetween of Cu;

[0040] The hydropower steel contains Mo in an amount of 0.40%, 0.45%, 0.50% or any range or sub-range therebetween.

[0041] In some embodiments of the present invention, during the smelting process, when the P content in the molten steel reaches 50-100 ppm, dephosphorization is stopped, and the P content of the finished hydropower steel product is controlled within the range of 0.005-0.010%.

[0042] In the following embodiments of the present invention, a 200 mm continuous casting billet is used in the casting process.

[0043] In some embodiments of the present invention, the heating conditions are: heating temperature 1160-1180°C (such as 1160°C, 1170°C or 1180°C), heating rate ≤280°C / h, preferably 230-278°C / h (such as 230°C / h, 250°C / h or 275°C / h), total heating time 200-300min (such as 246min, 270min or 300min).

[0044] In some embodiments of the present invention, the rolling adopts a two-stage rolling + post-rolling rapid cooling (DQ) process;

[0045] The temperature of the first rolling stage is 1000-1080°C (such as 1000°C, 1030°C or 1080°C); the temperature of the second rolling stage is 880-930°C (such as 880°C, 900°C or 930°C). The condition of rapid cooling after rolling is: cooling rate 16-22°C / s (such as 16°C / s, 18°C / s or 21°C / s).

[0046] In some embodiments of the present invention, the tempering treatment conditions are: tempering temperature 580-650°C (such as 580°C, 600°C or 630°C), holding time 2.5-6min / mm (such as 2.5min / mm, 4min / mm or 6min / mm).

[0047] The atmospheric corrosion resistance index I value of the hydroelectric steel prepared by the above process is ≥8, and the calculation formula is I=26.01(Cu%)+3.88(Ni%)+1.20(Cr%)+1.49(Si%)+7.28(P%)-7.29(Cu%)(Ni%)-9.10(Ni%)(P%)-33.39(Cu%) 2 According to the international standard ASTM G101-01 Standard Guide for Evaluating Atmospheric Corrosion Resistance of Low Alloy Steels, when the I value is ≥ 6, it indicates that the low alloy steel has weathering resistance.

[0048] The smelting and continuous casting process in the following embodiments of the present invention adopts conventional methods in the art to achieve the purpose, and the influence of specific process parameters on the reaction is not discussed as the creativity of the present invention.

[0049] The "room temperature" in the present invention refers to 20-30°C unless otherwise specified.

[0050] The raw materials used in the present invention are all purchased from the market.

[0051] The technical solution of the present invention is further illustrated by the following embodiments.

[0052] Example 1

[0053] Preparation of a 10mm thick, weather-resistant, 1000MPa grade hydropower steel plate:

[0054] (1) Hydropower steel includes the following components in mass percentage: C: 0.07%, Si: 0.25%, Mn: 0.65%, P: 0.006%, S=0.004%, Alt: 0.050%, Nb: 0.020%, V: 0.030%, Ti: 0.012%, Ni: 0.70%, Cr: 1.90%, Cu: 0.30%, Mo: 0.40%, and the balance is Fe and unavoidable impurities;

[0055] The atmospheric corrosion resistance index I value of hydropower steel is calculated according to the formula: I = 26.01 (Cu%) + 3.88 (Ni%) + 1.20 (Cr%) + 1.49 (Si%) + 7.28 (P%) - 7.29 (Cu%) (Ni%) - 9.10 (Ni%) (P%) - 33.39 (Cu%) 2 =9.3;

[0056] (2) Smelting and continuous casting process: Weigh the components according to the mass percentages shown in step (1) to obtain a mixed material, subject the mixed material to converter / electric furnace rough refining, LF refining and VD / RH vacuum treatment in sequence, and then cast a 200 mm specification continuous casting billet to obtain a steel billet;

[0057] Converter / electric furnace rough refining process: The edge of the ladle must be kept clean to reduce the mixing of impurities, ensure the purity of the molten steel, ensure that C≤0.08%, P≤0.010% when tapping, ensure that the tapping port is smooth and regular, and nitrogen blowing is not allowed. During the tapping process, it is forbidden to add refined slag, Si-containing alloys and aluminum particles;

[0058] LF refining process: The alloys used in the refining process mainly use electrolytic manganese and nickel iron (spare nickel plate), copper plate (scrap copper is strictly prohibited), molybdenum iron and low aluminum alloy. When the temperature reaches above 1600℃, take samples for testing to ensure that the composition meets the requirements (P: 0.005-0.010%, S≤0.005%); add titanium iron into the furnace 10 minutes before the refining bag operation;

[0059] VD / RH vacuum treatment process: VD pressure holding time is controlled within 10-20 minutes. After the air-breaking treatment, soft blowing should be carried out immediately by introducing materials such as rice husks. The soft blowing time should be controlled within 5-15 minutes.

[0060] (3) Heating process: heating the steel billet to 1180° C., with an average heating rate of 258° C. / h, and ensuring that the total heating time is 270 min;

[0061] (4) Rolling process: The first stage rolling temperature was 1080°C, the final rolling temperature was 1012°C, and the steel thickness was 50 mm; the second stage rolling temperature was 930°C, and the final rolling temperature was 850°C; after rolling, a post-rolling rapid cooling (DQ) process was performed, and the cooling rate was 21°C / s, and a sample with a thickness of 10 mm was obtained;

[0062] (5) Tempering process: The sample obtained by the hot rolling treatment is tempered at 630° C. and kept at this temperature for 6 min / mm to obtain the hydropower steel plate.

[0063] Example 2

[0064] Preparation of a 45mm thick, weather-resistant, 1000MPa grade hydropower steel plate:

[0065] (1) Hydropower steel includes the following components in percentage by mass: C: 0.10%, Si: 0.35%, Mn: 0.85%, P: 0.008%, S: 0.004%, Alt: 0.030%, Nb: 0.030%, V: 0.045%, Ti: 0.016%, Ni: 1.20%, Cr: 1.60%, Cu: 0.25%, Mo: 0.50%, and the balance is Fe and unavoidable impurities;

[0066] The atmospheric corrosion resistance index I value of hydropower steel is calculated according to the formula: I = 26.01 (Cu%) + 3.88 (Ni%) + 1.20 (Cr%) + 1.49 (Si%) + 7.28 (P%) - 7.29 (Cu%) (Ni%) - 9.10 (Ni%) (P%) - 33.39 (Cu%) 2 =8.64;

[0067] (2) Smelting and continuous casting process: Weigh the components according to the mass percentages shown in step (1) to obtain a mixed material, subject the mixed material to converter / electric furnace rough refining, LF refining and VD / RH vacuum treatment in sequence, and then cast a 200 mm specification continuous casting billet to obtain a steel billet;

[0068] Converter / electric furnace rough refining process: The edge of the ladle must be kept clean to reduce the mixing of impurities, ensure the purity of the molten steel, ensure that C≤0.08%, P≤0.010% when tapping, ensure that the tapping port is smooth and regular, and nitrogen blowing is not allowed. During the tapping process, it is forbidden to add refined slag, Si-containing alloys and aluminum particles;

[0069] LF refining process: The alloys used in the refining process mainly use electrolytic manganese and nickel iron (spare nickel plate), copper plate (scrap copper is strictly prohibited), molybdenum iron and low aluminum alloy. When the temperature reaches above 1600℃, take samples for testing to ensure that the composition meets the requirements (P: 0.005-0.010%, S≤0.005%); add titanium iron into the furnace 10 minutes before the refining bag operation;

[0070] VD / RH vacuum treatment process: VD pressure holding time is controlled within 10-20 minutes. After the air-breaking treatment, soft blowing should be carried out immediately by introducing materials such as rice husks. The soft blowing time should be controlled within 5-15 minutes.

[0071] (3) Heating process: heating the steel billet to 1160° C., with an average heating rate of 278° C. / h, and ensuring a total heating time of 246 min;

[0072] (4) Rolling process: The first stage of rolling has a starting temperature of 1000°C, a final rolling temperature of 980°C, and a steel thickness of 110 mm; the second stage of rolling has a starting temperature of 880°C, and a final rolling temperature of 860°C; after rolling, a post-rolling rapid cooling (DQ) process is performed, with a cooling rate of 16°C / s, to obtain a sample with a thickness of 45 mm;

[0073] (5) Tempering process: The sample obtained by the hot rolling treatment is tempered at 580° C. and kept at this temperature for 2.5 min / mm to obtain the hydropower steel plate.

[0074] Example 3

[0075] Preparation of a 25mm thick, weather-resistant, 1000MPa grade hydropower steel plate:

[0076] (1) Hydropower steel includes the following components in percentage by mass: C: 0.08%, Si: 0.30%, Mn: 0.75%, P: 0.010%, S=0.005%, Alt: 0.020%, Nb: 0.025%, V: 0.030%, Ti: 0.020%, Ni: 0.90%, Cr: 1.75%, Cu: 0.20%, Mo: 0.45%, and the balance is Fe and unavoidable impurities;

[0077] The atmospheric corrosion resistance index I value of hydropower steel is calculated according to the formula: I = 26.01 (Cu%) + 3.88 (Ni%) + 1.20 (Cr%) + 1.49 (Si%) + 7.28 (P%) - 7.29 (Cu%) (Ni%) - 9.10 (Ni%) (P%) - 33.39 (Cu%) 2 =8.58;

[0078] (2) Smelting and continuous casting process: Weigh the components according to the mass percentages shown in step (1) to obtain a mixed material, subject the mixed material to converter / electric furnace rough refining, LF refining and VD / RH vacuum treatment in sequence, and then cast a 200 mm specification continuous casting billet to obtain a steel billet;

[0079] Converter / electric furnace rough refining process: The edge of the ladle must be kept clean to reduce the mixing of impurities, ensure the purity of the molten steel, ensure that C≤0.08%, P≤0.010% when tapping, ensure that the tapping port is smooth and regular, and nitrogen blowing is not allowed. During the tapping process, it is forbidden to add refined slag, Si-containing alloys and aluminum particles;

[0080] LF refining process: The alloys used in the refining process mainly use electrolytic manganese and nickel iron (spare nickel plate), copper plate (scrap copper is strictly prohibited), molybdenum iron and low aluminum alloy. When the temperature reaches above 1600℃, take samples for testing to ensure that the composition meets the requirements (P: 0.005-0.010%, S≤0.005%); add titanium iron into the furnace 10 minutes before the refining bag operation;

[0081] VD / RH vacuum treatment process: VD pressure holding time is controlled within 10-20 minutes. After the air-breaking treatment, soft blowing should be carried out immediately by introducing materials such as rice husks. The soft blowing time should be controlled within 5-15 minutes.

[0082] (3) Heating process: heating the steel billet to 1170° C., with an average heating rate of 230° C. / h, and ensuring that the total heating time is 300 min;

[0083] (4) Rolling process: The first stage rolling temperature is 1030°C, the final rolling temperature is 995°C, and the steel thickness is 70 mm; the second stage rolling temperature is 900°C, and the final rolling temperature is 855°C; after rolling, a post-rolling rapid cooling (DQ) process is performed, and the cooling rate is 18°C / s, and a sample with a thickness of 25 mm is obtained;

[0084] (5) Tempering process: The sample obtained by the hot rolling treatment is tempered at 600° C. and kept at this temperature for 4 min / mm to obtain the hydropower steel plate.

[0085] Performance Test:

[0086] The tensile and impact performance tests were performed on the hydroelectric steel plates prepared in Examples 1-3.

[0087] The tensile test was carried out according to GB / T228.1-2021 standard, with a tensile rate of 1 mm / min and a transverse direction.

[0088] According to GB / T 229-2020, low-temperature impact tests at -40°C and -60°C were performed (according to the requirements of T / SSEA 0225-2022 1000MPa high-strength steel plates for hydropower, only -60°C is required), and the test direction is horizontal. Three samples were taken for low-temperature impact tests in each embodiment.

[0089] The test results are shown in Table 1.

[0090] Table 1 Tensile and impact performance results of hydroelectric steel plates prepared in Examples 1-3

[0091]

[0092] Note: Rp 0.2represents: room temperature yield strength; Rm represents: tensile strength; A 50 Indicates: elongation; -60℃Akv indicates: -60℃ impact value.

[0093] It can be seen from Table 1 that the performance of the hydropower steel plates prepared by using Examples 1-3 of the present invention meets the following indicators: room temperature yield strength is 915-937MPa, tensile strength is 1013-1045MPa, yield strength ratio ≤0.94, elongation ≥14%, -40℃ impact value ≥190J, -60℃ impact value ≥142J.

[0094] The hydroelectric steel plates prepared in Examples 1-3 were subjected to salt spray corrosion resistance tests. The test standard was GB / T10125-2012, and the corrosive agent was 3.5% NaCl solution. The test results are shown in Table 2.

[0095] Table 2 Salt spray test corrosion weight loss results of hydroelectric steel plates prepared in Examples 1-3

[0096]

[0097] It can be seen from the results in Table 2 that on the 5th and 10th days of the test, the weight loss from corrosion of Examples 1-3 was less than 60% of the weight loss of the reference sample, indicating that its corrosion resistance is better than that of ordinary low alloy steel and the example steel plates have weather resistance.

[0098] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A hydroelectric steel with a thickness of no more than 45 mm and a weather resistance of 1000 MPa, characterized in that: The invention comprises the following components in mass percentage: C: 0.07-0.10%, Si: 0.25-0.35%, Mn: 0.65-0.85%, P: 0.005-0.010%, S≤0.005%, Alt: 0.020-0.050%, Nb: 0.020-0.030%, V: 0.030-0.045%, Ti: 0.012-0.020%, Ni: 0.70-1.20%, Cr: 1.60-1.90%, Cu: 0.20-0.30%, Mo: 0.40-0.50%, and the balance is Fe and unavoidable impurities.

2. The hydroelectric steel with a thickness of no more than 45 mm and a weather resistance of 1000 MPa according to claim 1, characterized in that: The thickness of the hydroelectric steel is 6-45 mm.

3. The hydroelectric steel with a thickness of no more than 45 mm and a weather resistance of 1000 MPa according to claim 1, characterized in that: The atmospheric corrosion resistance index I value of the hydroelectric steel is ≥8, and the atmospheric corrosion resistance index I value calculation formula is I=26.01(Cu%)+3.88(Ni%)+1.20(Cr%)+1.49(Si%)+7.28(P%)-7.29(Cu%)(Ni%)-9.10(Ni%)(P%)-33.39(Cu%) 2 .

4. A method for preparing a hydroelectric steel having a thickness of no more than 45 mm and a weather resistance of 1000 MPa as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: The components are weighed according to mass percentage to obtain a mixed material, and the mixed material is smelted and cast to obtain a steel billet; the steel billet is sequentially heated, rolled, rapidly cooled after rolling, and tempered to obtain the hydropower steel.

5. The method for preparing the 1000MPa grade hydroelectric steel with a thickness of no more than 45mm and weather resistance according to claim 4, characterized in that: During the smelting process, when the P content in the molten steel reaches 50-100 ppm, dephosphorization is stopped, and the P content of the finished hydropower steel product is controlled within the range of 0.005-0.010%.

6. The method for preparing the 1000MPa grade hydroelectric steel with a thickness of no more than 45mm and weather resistance according to claim 4, characterized in that: The casting process uses a 200 mm specification continuous casting billet.

7. The method for preparing the 1000MPa grade hydroelectric steel with a thickness of no more than 45mm and weather resistance according to claim 4, characterized in that: The heating conditions are: heating temperature 1160-1180° C., heating rate ≤280° C. / h, and total heating time 200-300 min.

8. The method for preparing the 1000MPa grade hydroelectric steel with a thickness of no more than 45mm and weather resistance according to claim 4, characterized in that: The specific operation steps of the rolling include: first stage rolling at 1000-1080°C, and second stage rolling at 880-930°C; and / or The condition of rapid cooling after rolling is: cooling rate 16-22°C / s.

9. The method for preparing hydropower steel with a thickness of no more than 45 mm and a weather resistance of 1000 MPa according to claim 4, characterized in that: The tempering treatment conditions are: tempering temperature 580-650°C, and holding time 2.5-6 min / mm.

10. Application of the hydroelectric steel with a thickness of no more than 45 mm and weather resistance of 1000 MPa as claimed in any one of claims 1 to 3 in the field of pumped storage.

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