High-strength corrosion-resistant steel for polar region cold-resistant wind power tower drum and manufacturing method of high-strength corrosion-resistant steel

Abstract

The invention discloses high-strength corrosion-resistant steel for a polar region cold-resistant wind power tower drum and a manufacturing method of the high-strength corrosion-resistant steel. The high-strength corrosion-resistant steel comprises the following components in percentage by weight: 0.08 to 0.14 percent of C, 0.80 to 1.40 percent of Si, 0.4 to 0.8 percent of Mn, less than or equal to 0.010 percent of P, less than or equal to 0.0020 percent of S, 0.60 to 1.00 percent of Cr, 0.5 to 1.0 percent of Ni, 0.05 to 0.40 percent of Mo, 0.3 to 0.6 percent of Cu, 0.01 to 0.06 percent of Al, 0.006 to 0.015 percent of Ti, 0.0005 to 0.0030 percent of Mg and the balance of Fe and other inevitable impurities. 5.8 < = alpha < = 8.8 and 50 < = beta < = 72 need to be satisfied simultaneously. The high-strength corrosion-resistant steel not only has high strength, excellent low-temperature impact toughness and good cold resistance, but also has excellent corrosion resistance, can be used without coating, and protects the polar region environment. The yield strength is larger than or equal to 500 MPa, the tensile strength ranges from 610 MPa to 770 MPa, the ductility is larger than or equal to 17%, the impact energy at the temperature of-60 DEG C is larger than or equal to 100 J, TD (Tkb) is smaller than or equal to-30 DEG C, NDTT is smaller than or equal to-65 DEG C, CTOD at the temperature of-30 DEG C is larger than or equal to 1.2 mm, welding CTOD at the temperature of-30 DEG C is larger than or equal to 0.50 mm, and the corrosion rate in the polar region atmospheric environment is smaller than or equal to 0.80 g / (m < 2 > * h).

Description

Technical Field

[0001] The present invention belongs to the technical field of low-alloy high-strength steels, and particularly relates to a high-strength corrosion-resistant steel for polar anti-wind power generation tower barrels and a manufacturing method thereof. Background Art

[0002] As a renewable clean energy source, wind energy has developed rapidly globally. In 2022, the newly installed lifting capacity of global wind power reached 77.6 GW, including 68.8 GW for onshore wind power installations and 8.8 GW for offshore wind power installations, with a cumulative installed wind power capacity of 923 GW.

[0003] Currently, there are 83 scientific research stations in Antarctica, 53 of which are inhabited all year round. 80-90% of the electricity used still comes from fuel power generation. The pollution of the polar environment caused by fuel power generation cannot be ignored. International relevant organizations have repeatedly recommended that countries around the world convert fuel power generation in Antarctica into clean energy power generation. However, due to the harsh polar environment, it has been difficult to achieve for many years. Currently, the utilization of clean energy in Antarctica by countries around the world is all in the application test stage. Among them, the 100-kilowatt wind-solar energy storage built at Princess Elisabeth Station in Belgium has begun to be applied. In the polar regions, construction, navigation, and transportation all require energy, and it is necessary to continue to build large-capacity clean energy units.

[0004] The polar night period in the Arctic and Antarctic is up to 179 days. The average temperature from January to March is about -40°C to -20°C. The annual average snow accumulation time near the North Pole exceeds 360 days. Extreme low temperatures of -65°C to -70°C may occur in winter at the Arctic wind farms, posing strict requirements for wind power support materials.

[0005] Chinese Patent CN106435369A discloses "A normalized corrosion-resistant wind power steel with excellent low-temperature toughness containing Cr and its production method". The steel components and their weight percentage contents are: C: 0.04-0.09%, Si: 0.33-0.40%, Mn: 1.41-1.61%, P≤0.015%, S≤0.008%, Als: 0.030-0.040%, Nb: 0.038-0.051%, Cr: 0.40-0.8%, and the rest is Fe and inevitable impurities; and it satisfies the formula: Cr / (10*C): 0.87-1.00; (Cr + Mn) / (Als + Nb): 19.23-20.37. This patent adopts a low-carbon, medium-manganese, and high-niobium composition system. However, due to the use of the normalizing process, its yield strength is only 360 MPa, and the strength grade is relatively low, which cannot well meet the development requirements of large-capacity wind power steel.

[0006] Chinese Patent CN108330393A discloses "a wind power steel and its preparation method". The steel components and their weight percentage contents are as follows: C: 0.05 - 0.10%; Si: 0.22 - 0.42%; Mn: 1.26 - 1.42%; P ≤ 0.015%; S ≤ 0.008%; Als: 0.015 - 0.028%; V: 0.10 - 0.15%; Cr: 0.80 - 1.35%; Mo: 0.10 - 0.20%; Ce: 0.08 - 0.15%. Among them, 16.7% ≤ (Cr + Mn) / Mo ≤ 22.2%; 2.56% ≤ 5C + 8V + Mn ≤ 2.87%. This patent adopts a composition system of low-carbon medium-manganese, Cr, and Mo alloying, combined with a preparation method of hot rolling + normalizing, to obtain a wind power steel of 420MPa grade. However, the steel grade is still relatively low and cannot meet the requirements of high-strength wind power steel.

[0007] Chinese Patent CN115354240A discloses "an economical seawater erosion-resistant steel plate and its manufacturing method". The steel components and their weight percentage contents are as follows: C: 0.04 - 0.10%, Si: 0.10 - 0.20%, Mn: 1.20 - 1.40%, Nb: 0.010 - 0.025%, Als: 0.015 - 0.035%, Cr: 0.10 - 0.30%, P < 0.010%, S < 0.003%, CEV ≤ 0.38%, and the rest is Fe and inevitable impurities. By reducing the carbon content, reasonably adjusting the relative contents of various elements, combined with controlling the cleanliness inside the steel, subsequent controlled rolling, and controlled cooling to achieve a uniform structure, the obtained steel plate has excellent strength and toughness, seawater erosion resistance, and wear resistance. However, the alloying elements added in this invention are limited, and the carbon equivalent is relatively low, which cannot meet the requirements of polar large-thickness wind power steel. Summary of the Invention

[0008] The purpose of the present invention is to provide a high-strength corrosion-resistant steel for polar anti-cold wind power tower barrels and its manufacturing method. This steel not only has high strength, excellent low-temperature impact toughness, but also has good cold resistance. At the same time, the steel plate has excellent corrosion resistance and can be used without painting to protect the polar environment. Its yield strength ≥ 500MPa, tensile strength is 610 - 770MPa, elongation ≥ 17%, impact energy at -60°C ≥ 100J, T D(Tkb) ≤ -30°C, NDTT ≤ -65°C, CTOD at -30°C ≥ 1.0mm, welded CTOD at -30°C ≥ 0.38mm, and the corrosion rate in the polar atmospheric environment ≤ 0.80g / (m 2 *h); It is particularly suitable for the construction of polar wind power pile foundations and tower barrels, meeting the needs of polar clean wind power energy.

[0009] To achieve the above purpose, the technical solution of the present invention is:

[0010] A high-strength corrosion-resistant steel for polar anti-wind power generation tower barrels, the chemical composition of which is by weight percentage: C: 0.08 - 0.14%, Si: 0.80 - 1.40%, Mn: 0.4 - 0.8%, P ≤ 0.010%, S ≤ 0.0020%, Cr: 0.60 - 1.00%, Ni: 0.5 - 1.0%, Mo: 0.05 - 0.40%, Cu: 0.3 - 0.6%, Al: 0.01 - 0.06%, Ti: 0.006 - 0.015%, Mg: 0.0005 - 0.0030%, and the balance includes Fe and other inevitable impurities; and it needs to satisfy simultaneously:

[0011] 5.8 ≤ α ≤ 8.8, α = 26.01Cu + 3.88Ni + 1.20Cr + 1.49Si + 17.28P - 7.29Cu*Ni - 9.10Ni*P - 33.39Cu*Cu;

[0012] 50 ≤ β ≤ 72,

[0013] Further, the balance is Fe and other inevitable impurities.

[0014] The microstructure of the high-strength corrosion-resistant steel described in the present invention is ferrite + tempered bainite, where the volume fraction of ferrite is 10 - 25%, and the volume fraction of tempered bainite is 75 - 90%.

[0015] The yield strength of the high-strength corrosion-resistant steel described in the present invention ≥ 500 MPa, the tensile strength is 610 - 770 MPa, the elongation ≥ 17%, the impact energy at -60°C ≥ 100 J, T D(Tkb) ≤ -30°C, NDTT ≤ -65°C, the CTOD at -30°C ≥ 1.2 mm, the welded CTOD at -30°C ≥ 0.50 mm, and the corrosion rate in the polar atmospheric environment ≤ 0.80 g / (m 2 *h).

[0016] In the chemical composition design of the high-strength corrosion-resistant steel for polar anti-wind power generation tower barrels described in the present invention:

[0017] C: The present invention adopts medium-carbon design. On the one hand, by utilizing the interstitial strengthening and precipitation strengthening effects of carbon, it ensures that the steel plate of the invention has appropriate strength; on the other hand, it prevents excessive carbon from reducing the low-temperature toughness and welding performance of the steel plate. Therefore, the C content in the present invention is controlled at 0.08 - 0.14%.

[0018] Si: It is a common weak deoxidizing element in steelmaking. By means of solid solution strengthening, it can improve the strength of the steel plate and at the same time enhance the corrosion resistance of the steel plate. However, excessive silicon exacerbates the decarburization on the surface of the steel plate and reduces the toughness of the steel. Therefore, in this invention, the Si content is controlled within 0.80 - 1.40%.

[0019] Mn: It is the most basic alloying element in low-alloy high-strength steel grades, and it improves the strength of the steel through solid solution strengthening. However, too high Mn content is likely to cause segregation at the center of the steel plate and reduce the low-temperature toughness. Therefore, in this invention, the Mn content is 0.4 - 0.8%.

[0020] P Phosphorus: It is an inevitable harmful impurity element in steel. Phosphorus is unevenly distributed in the steel and concentrated at the grain boundaries, affecting the grain boundary structure and being prone to cold brittleness at low temperatures. Therefore, in this invention, P ≤ 0.010% is controlled.

[0021] S Sulfur: It is an inevitable harmful impurity element in steel, which is prone to form defects such as segregation and inclusions, deteriorating the welding performance, impact toughness and fatigue performance of the steel plate. Therefore, in this invention, S ≤ 0.0020% is controlled, and through inclusion modification technology, the inclusions should be spheroidized in morphology, refined in size and evenly distributed to reduce their influence on toughness and corrosion resistance.

[0022] Cr: It can improve the corrosion resistance of the steel, but Cr is a precious metal element. Considering the cost, therefore, in this invention, the Cr content is controlled within 0.60 - 1.00%.

[0023] Ni: It can improve the low-temperature toughness of steel, and at the same time plays a great role in improving the corrosion resistance of steel in polar environments, inhibiting the reverse effect of corrosion and pitting tendency. However, when the Ni content is too high, sticky scale is likely to form on the surface of the slab, which is difficult to remove, affecting the surface quality and fatigue performance of the steel plate, and the cost is relatively high. Therefore, in this invention, the Ni content is controlled within 0.5 - 1.0%.

[0024] Mo: It is an important element to improve the hardenability of steel, enhancing the thickness-direction property uniformity and corrosion resistance. However, too much Mo will increase the cold cracking tendency of the steel plate and also increase the cost at the same time. Therefore, in this invention, the Mo content is controlled within 0.05 - 0.40%.

[0025] Copper Cu: Appropriately increasing the hardenability of steel can improve the atmospheric corrosion resistance of steel. However, too high Cu will deteriorate the welding performance of steel. Therefore, in this invention, the Cu content is controlled within 0.30 - 0.60%.

[0026] Al: It is an element added to the steel for deoxidation. After complete deoxidation, it reduces the oxygen content in the material and improves the aging performance; in addition, appropriate Al is beneficial to refine the grains and improve the strength and toughness of the steel. Therefore, in this invention, the Al content is controlled within 0.01 - 0.06% to meet the deoxidation requirements.

[0027] Ti: It is a strong nitrogen-fixing element that inhibits the adverse effects of excessive nitrogen content on the properties of steel. At the same time, the formation of TiN precipitation phase can inhibit the excessive growth of grains during the heating process of slab and steel plate. Therefore, in the present invention, the Ti content is controlled within 0.006 - 0.015%.

[0028] Mg: It can improve the morphology of sulfides, refine inclusions, and enhance the corrosion resistance of steel plates. If the Mg content is too low, it cannot play the role of inclusion modification, and if it is too high, it is easy to form excessive MgO and MgS, blocking the nozzle. Therefore, in the present invention, the Mg content is controlled within 0.0005 - 0.0030%.

[0029] Furthermore, in the high-strength corrosion-resistant steel described in the present invention, the mass percentage contents of each chemical element also meet the following requirements: 5.8 ≤ α ≤ 8.8, 50 ≤ β ≤ 72, where:

[0030] α = 26.01Cu + 3.88Ni + 1.20Cr + 1.49Si + 17.28P - 7.29Cu*Ni - 9.10Ni*P - 33.39Cu*Cu;

[0031]

[0032] For each chemical element in the formula, the value before the percentage sign of the mass percentage content of this chemical element is substituted.

[0033] Corrosion-resistant elements such as Cu, Ni, Cr, Si, and P can be enriched in the rust layer, improving the stability and compactness of the rust layer. The setting of the α value comprehensively considers the corrosion resistance of Cu, Ni, Cr, Si, and P to ensure the comprehensive corrosion resistance of the steel plate. However, too high an α value increases the alloy cost and reduces the welding performance of the steel plate. Therefore, in the present invention, the α value is controlled within 5.8 - 8.8.

[0034] The β value limits Si, Mo, Cu, etc. On the one hand, it improves the hardenability of the steel plate, and on the other hand, it increases the electrode potential of the steel plate, thereby improving the corrosion resistance. However, excessive alloy addition reduces the welding performance of the steel plate. Therefore, in the present invention, the β value is controlled within 50 - 72.

[0035] Furthermore, in the high-strength corrosion-resistant steel described in the present invention, its microstructure is ferrite + tempered bainite, and the ferrite proportion is 10 - 25%, and the tempered bainite proportion is 75 - 90%, thereby ensuring that the steel has good strength-ductility matching.

[0036] Furthermore, in the high-strength corrosion-resistant steel described in the present invention, its yield strength ≥ 500 MPa, tensile strength is 610 - 770 MPa, elongation ≥ 17%, impact energy at -60 °C ≥ 100 J, T D(Tkb) ≤ -30 °C, NDTT ≤ -65 °C, CTOD at -30 °C ≥ 1.2 mm, welding CTOD at -30 °C ≥ 0.50 mm, corrosion rate in polar atmospheric environment ≤ 0.80 g / (m 2 *h).

[0037] The manufacturing method of the high-strength corrosion-resistant steel for polar cold-resistant wind power tower barrels of the present invention includes the following steps:

[0038] 1) Smelting and continuous casting

[0039] Smelt according to the above composition, continuous casting speed 0.5 - 1.0 m / min, dynamic soft reduction solid fraction 0.35 - 0.70, reduction amount 6 - 10 mm;

[0040] 2) Reheating

[0041] The slab heating temperature is T h ±15 °C, unit °C;

[0042] 3) Controlled rolling

[0043] The rolling start temperature T sr = 0.95T h ±15 °C; the final rolling temperature is T fr ±15 °C, unit °C. After rolling, the steel plate is cooled to below 600 °C and stacked and cooled in a heat preservation pit;

[0044] 4) Heat treatment

[0045] Quenching, the quenching temperature is T q ±15 °C, unit °C; the time in the furnace is 1.6t ± 15 min, t is the thickness of the steel plate, unit mm, and after heating, it is cooled to room temperature at a speed greater than 10 °C / s;

[0046] Tempering, the tempering temperature is T t ±15 °C, unit °C; the time in the furnace is 1.6t ± 15 min, t is the thickness of the steel plate, unit mm, and after heating, it is air-cooled to room temperature.

[0047] Furthermore, in step 1), hot metal pretreatment, converter smelting, LF refining, RH refining, inclusion beneficial treatment and continuous casting are carried out in sequence. Among them, in the inclusion beneficial treatment stage, a composite inclusion with MgO + Al 2 O 3 as the core and coated with (Ca, Mn)S is formed. The size of this composite inclusion is 0.2 - 2.5 um, and the number of composite inclusions in this size range accounts for more than 95% of the total number of inclusions.

[0048] Furthermore, in step 1), during the hot metal pretreatment desulfurization stage, ensure that the sulfur content in the hot metal is ≤ 0.0035%; during the LF refining stage, control the FeO + MnO content in the slag to be ≤ 1%, and control the basicity R of the slag > 9, where R = (CaO + MgO + MnO) / (SiO 2 +P 2 O 5 ), and substitute the mass percentage content of each substance in the formula; during the RH refining stage, perform vacuum treatment, and the vacuum treatment time is ≥ 22 min; during the inclusion beneficial treatment stage, add Mg wire in the form of cored wire, and the wire feeding speed is 200 - 300 m / min.

[0049] Preferably, in step 3), the reduction per pass is 8 - 12%, and the cumulative reduction is ≥ 60%.

[0050] In the manufacturing method described in the present invention:

[0051] For the incoming hot metal, perform pretreatment desulfurization, converter smelting and alloying, LF refining and alloying, RH refining, inclusion beneficial treatment, and continuous casting in sequence.

[0052] Among them, during the hot metal pretreatment desulfurization stage, ensure that the sulfur content in the hot metal is ≤ 0.0035%; the purpose of setting the above process is to ensure that the steel grade has a low sulfur content and improve the low - temperature toughness of the steel plate.

[0053] During the converter smelting stage, ensure that the alloying elements of Cr, Ni, Cu, and Mo meet the composition requirements. After the converter alloying is completed, tap the steel with slag control; by using slag - controlled tapping, the thickness of the slag layer in the ladle is controlled below 50 mm, which can avoid re - phosphorus and improve the recovery rate of alloys, and reduce oxide inclusions.

[0054] During the LF furnace smelting stage, make a white slag, and the basicity R of the slag > 9,

[0055] R = (CaO + MgO + MnO) / (SiO 2 +P 2 O 5 ).

[0056] The above - mentioned process setting of the refining slag with high basicity, low melting point, and low iron oxide can effectively desulfurize, absorb inclusions, and reduce the total oxygen in the steel.

[0057] Perform desulfurization and control the S content in the molten steel to be less than 0.0012%; perform vacuum treatment in RH, and the vacuum treatment time is ≥ 22 min. The above process setting can effectively remove large inclusions in the molten steel and improve the impact toughness of the steel plate.

[0058] After breaking the vacuum, beneficial treatment of inclusions is carried out. Mg wire is added in the form of cored wire, and the wire feeding speed is 200 - 300 m / min. During the beneficial treatment stage of inclusions, composite inclusions with MgO + Al 2 O 3 as the core and coated with (Ca, Mn)S are formed. The size of the composite inclusions is 0.2 - 2.5 μm, and the number of composite inclusions in this size range accounts for more than 95% of the total number of inclusions. The above process settings can effectively modify and refine the inclusions, improving the low-temperature toughness of the steel plate.

[0059] The continuous casting drawing speed is 0.5 - 1.0 m / min; the solid phase rate of dynamic soft reduction is 0.35 - 0.70, and the reduction amount is 6 - 10 mm, which can form a billet structure with a dense core and improve the cold-resistant service ability of the steel plate.

[0060] Control the slab heating temperature to be T h ±15 °C, unit °C. Setting the above slab reheating temperature is to ensure the full solid solution of TiN and promote the homogenization of segregation elements, reduce the macroscopic and microscopic segregation in the steel, reduce the corrosion primary battery formed due to the different potential differences between different phases and components, and reduce the corrosion resistance of the steel plate.

[0061] During the rolling process, control the starting rolling temperature T sr = 0.95T h ±15 °C, unit °C; mainly to ensure that the steel plate is rolled at a relatively high temperature in the recrystallization zone to fully recrystallize and form uniform equiaxed austenite grains.

[0062] The finishing rolling temperature is T fr ±15 °C, unit °C. For each chemical element in the above formula, substitute the value before the percentage sign of the mass percentage content of the chemical element. It can ensure that the steel plate is rolled above the non-static recrystallization temperature, prevent mixed grains and non-uniform grains; secondly, ensure that there is enough temperature drop space during the rolling process.

[0063] Furthermore, during the rolling process, the reduction amount per rolling pass is 8 - 12%, and the cumulative reduction amount ≥ 60%. The reduction amount per rolling pass of 8 - 12% is mainly to ensure that the steel plate has enough recrystallization driving force in each pass, and at the same time has enough rolling passes to homogenize the grains of the steel plate to meet the requirement that the original austenite grain size after rolling remains between 20 - 25 μm. Correspondingly, controlling the cumulative reduction amount ≥ 60% is mainly to ensure that sufficient recrystallization occurs in the core of the steel plate, fully homogenize it, and ensure the strength and toughness properties and fracture crack arrest properties of the core. After rolling, the steel plate is cooled below 600 °C and stacked in a heat preservation pit for cooling.

[0064] During the heat treatment process, control the quenching temperature to be T q±15 °C, Unit: °C; The time in the furnace is 1.6t ± 15 min, where t is the thickness of the steel plate in mm. After heating, it is cooled to room temperature at a rate greater than 10 °C / s. The quenching temperature is set first to ensure that 75 - 90% of the austenitization transformation occurs in the steel plate, and 10 - 25% still remains in the undissolved ferrite state. Subsequently, water quenching can be carried out to obtain a high cooling rate, transform austenite into martensite structure, and keep the austenite grain size between 15 - 25 μm.

[0065] Control the tempering temperature to be T t ±15 °C, Unit: °C; The time in the furnace is 1.6t ± 15 min, where t is the thickness of the steel plate in mm. After heating, it is air-cooled to room temperature. The tempering temperature is set first to ensure that the steel plate has good mechanical properties and fracture arrest properties, second to eliminate the quenching stress in the steel plate by tempering to prevent corrosion caused by different forces in different parts of the steel plate, and finally, after tempering, the steel plate can obtain a ferrite + tempered martensite structure, combining soft and hard phases, with excellent low-temperature toughness. If the tempering temperature is too high, too much ferrite structure will form in the steel, reducing the strength and impact performance of the steel plate; while when the tempering temperature is too low, the strength of the steel plate is too high and the impact toughness is low.

[0066] Compared with the prior art, the present invention has the following advantages:

[0067] Existing wind power steel mostly adopts a low-carbon medium-manganese alloy design, not only with relatively low strength and toughness levels of the steel plate, but also the corrosion resistance cannot meet the requirements of extremely low-temperature high-strength wind power steel.

[0068] In the composition design of the present invention, a composition design of medium-carbon low-manganese, low-P low-S, alloying with chromium, nickel, molybdenum, copper, and micro-alloying treatment with aluminum, titanium, and magnesium is adopted. At the same time, the mass percentage contents of each chemical element are also controlled to meet the following requirements: 5.8 ≤ α ≤ 8.8, 50 ≤ β ≤ 72. The steel not only has high strength, excellent low-temperature impact toughness and welding performance, but also the steel plate has excellent corrosion resistance and can be used without painting. Its yield strength ≥ 500 MPa, tensile strength is 610 - 770 MPa, elongation ≥ 17%, impact energy at -60 °C ≥ 100 J, T D(Tkb) ≤ -30 °C, NDTT ≤ -65 °C, CTOD at -30 °C ≥ 1.2 mm, welded CTOD at -30 °C ≥ 0.50 mm, corrosion rate in polar atmospheric environment ≤ 0.80 g / (m 2 *h).

[0069] Based on the composition design, the present invention adopts a low-sulfur smelting process, a beneficial inclusion steel liquid treatment technology, a low segregation and high-density slab manufacturing technology, a large reduction rolling technology for steel plates, and a heat treatment process technology with high tissue uniformity design, enabling the steel plates to have good cold resistance and corrosion resistance while having high strength. In the existing smelting process of ultra-low wind power steel, the sulfur content is relatively high, and the inclusions are not beneficially treated. The microstructural uniformity in the thickness direction of the steel plate is low, resulting in a low toughness grade of the steel plate. Moreover, the rolling and cooling production processes do not accurately control the process parameters in combination with the composition, and cannot meet the production requirements of high strength. Detailed Embodiments

[0070] The present invention will be further described below in conjunction with embodiments.

[0071] The chemical composition of the steel in the embodiments of the present invention is shown in Table 1, and the balance includes Fe and inevitable impurities; the specific process parameters of the embodiments of the present invention are shown in Table 2.

[0072] The finished steel plates obtained by the present invention are subjected to tensile, Charpy V-notch impact, TKB test, NDT performance test (an important index for measuring the crack arrest performance of steel plates), parent metal CTOD test (an index for testing the fracture toughness of steel plates), and welded joint CTOD performance test. The performance results of the steel plates in the embodiments and comparative examples of the present invention are shown in Table 3.

[0073] It can be seen from Table 3 that the yield strength of the steel obtained by the present invention is ≥500 MPa, the tensile strength is 610 - 770 MPa, the elongation is ≥17%, the impact energy at -60 °C is ≥100 J, TD (Tkb) ≤ -30 °C, NDTT ≤ -65 °C, the CTOD at -30 °C is ≥1.2 mm, the welded CTOD at -30 °C is ≥0.50 mm, and the corrosion rate in the polar atmospheric environment is ≤0.80 g / (m 2 *h).

[0074] Test conditions for the corrosion rate in the polar atmospheric environment: During the test, 5% NaCl solution is used, and its temperature is 35 °C, the pH is 6.5 - 7.2, the average salt spray deposition rate is controlled: 1.5 mL / (80 cm 2 ·h), and the RH (relative humidity) is controlled between 95 - 100%.

[0075] Comparative Example 1 and Comparative Example 2 are the composition systems of current conventional wind power tower structure steel, in which the contents of C and Mn are relatively high, and the values of α and β are both low. The strength, low-temperature toughness and corrosion resistance of the steel plates are all poor.

[0076]

[0077]

[0078]

Claims

1. A high-strength corrosion-resistant steel for polar anti-wind power generation tower barrels, with its chemical composition by weight percentage as follows: C: 0.08 - 0.14%, Si: 0.80 - 1.40%, Mn: 0.4 - 0.8%, P ≤ 0.010%, S ≤ 0.0020%, Cr: 0.60 - 1.00%, Ni: 0.5 - 1.0%, Mo: 0.05 - 0.40%, Cu: 0.3 - 0.6%, Al: 0.01 - 0.06%, Ti: 0.006 - 0.015%, Mg: 0.0005 - 0.0030%, and the balance includes Fe and other inevitable impurities; and it needs to satisfy simultaneously 5.8 ≤ α ≤ 8.8, where α = 26.01Cu + 3.88Ni + 1.20Cr + 1.49Si + 17.28P - 7.29Cu*Ni - 9.10Ni*P - 33.39Cu*Cu; 50≤β≤72， 2. The high-strength corrosion-resistant steel for polar anti-wind power generation tower barrels as described in claim 1, characterized in that, the balance is Fe and other inevitable impurities.

3. The high-strength corrosion-resistant steel for polar anti-wind power generation tower barrels as described in claim 1 or 2, characterized in that, the microstructure of the high-strength corrosion-resistant steel is ferrite + tempered bainite, where the volume fraction of ferrite is 10 - 25%, and the volume fraction of tempered bainite is 75 - 90%.

4. The high-strength corrosion-resistant steel for polar anti-wind power generation tower barrels as described in claim 1 or 2 or 3, characterized in that, The yield strength of the high-strength corrosion-resistant steel is ≥500 MPa, the tensile strength is 610 - 770 MPa, the elongation is ≥17%, the impact energy at -60°C is ≥100 J, T D(Tkb) ≤ -30°C, NDTT ≤ -65°C, the CTOD at -30°C is ≥1.0 mm, the welded CTOD at -30°C is ≥0.50 mm, and the corrosion rate in the polar atmospheric environment is ≤0.80 g / (m 2 *h).

5. The manufacturing method of the high-strength corrosion-resistant steel for polar anti-wind power generation tower barrels as described in any one of claims 1 - 4, characterized in that, it includes the following steps: 1) Smelting and continuous casting Smelt according to the composition of claim 1 or 2, with the continuous casting speed of 0.5 - 1.0 m / min, the solid fraction for dynamic soft reduction of 0.35 - 0.70, and the reduction amount of 6 - 10 mm; 2) Reheating The slab heating temperature is T h ±15 °C, where the unit is °C; 3) Controlled rolling The starting rolling temperature is T sr = 0.95T h ±15 °C; the finishing rolling temperature is T fr ±15 °C, Unit: °C; After rolling, the steel plate is cooled to below 600 °C and then stacked and cooled in a heat preservation pit. 4) Heat treatment Quenching, the quenching temperature is T q ±15 °C, unit °C; the holding time in the furnace is 1.6t ± 15 min, where t is the thickness of the steel plate, unit mm, and after heating, it is cooled to room temperature at a rate greater than 10 °C / s; Tempering, tempering temperature is T t ±15 °C, unit °C; holding time in the furnace is 1.6t ± 15 min, where t is the thickness of the steel plate, unit mm, and after heating, it is air-cooled to room temperature.

6. The manufacturing method as described in claim 5, characterized in that, In step 1), hot metal pretreatment, converter smelting, LF refining, RH refining, inclusion beneficial treatment, and continuous casting are carried out in sequence. Among them, in the inclusion beneficial treatment stage, a composite inclusion with MgO + Al 2 O 3 as the core and coated with (Ca, Mn)S is formed. The size of the composite inclusion is 0.2 - 2.5 μm, and the number of the composite inclusions in this size range accounts for more than 95% of the total number of inclusions.

7. The manufacturing method as described in claim 6, characterized in that, in step 1), in the stage of hot metal pretreatment for desulfurization, ensure that the sulfur content of hot metal ≤ 0.0035%; During the LF refining stage, control FeO + MnO ≤ 1% in the slag, and control the basicity R of the slag > 9, where R = (CaO + MgO + MnO) / (SiO 2 +P 2 O 5 ), and substitute the mass percentage content of each substance in the formula; carry out vacuum treatment in the RH refining stage, with the vacuum treatment time ≥ 22 min; in the stage of inclusion beneficial treatment, add Mg wire in the form of cored wire, and the wire feeding speed is 200 - 300 m / min.

8. The manufacturing method as described in claim 5, characterized in that, in step 3), the reduction amount per pass is 8 - 12%, and the cumulative reduction amount ≥ 60%.

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