460MPa-grade wind power steel with high toughness, low temperature resistance and excellent crack arrest performance and production method of 460MPa-grade wind power steel

Abstract

The invention provides 460MPa-grade wind power steel with high toughness, low temperature resistance and excellent crack arrest performance and a production method of the 460MPa-grade wind power steel. The steel comprises the following alloy components in percentage by mass: 0.08-0.12% of C; 0.20% to 0.25% of Si; mn: 1.50 to 1.70%; 0.25 to 0.35 percent of Cr; 0.05 to 0.06 percent of Nb, V and Ti; 0.15 to 0.35 percent of Ni; the content of Als is 0.02 to 0.045 percent; 0.01 to 0.02 percent of Cu; 0.003% to 0.005% of Mo; and the balance of Fe and inevitable impurities. Compared with the prior art, the steel plate for wind power, which is low in cost, high in toughness, high in crack arrest performance and excellent in welding performance, is successfully prepared through component design of low carbon equivalent and low crack sensitivity coefficient assisted by a TMCP (Thermal Mechanical Control Processing) process, and meets the development requirements of deserts, gobi, deserts and other inland areas with severe environments and large-scale deep sea ocean wind turbine generators; and industrial batch production with stable performance can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of steel production, and more specifically, to a 460MPa-grade wind power steel with high strength, toughness, low temperature resistance and excellent anti-cracking performance and a production method thereof. Background Art

[0002] The development of resources in deep sea and polar regions and the demand for large-scale and lightweight equipment have put forward higher requirements for medium and thick steel structural materials with high strength, high toughness, high crack arrest performance and excellent welding performance. The working environment of wind power steel is harsh. Wind turbines are faced with the combined effects of various forms of load cyclic impacts such as wind and waves. Under the action of cyclic loads, the base structure and its welded joints are prone to fatigue fracture, which puts forward more stringent performance requirements on the materials. The strength grade of steel used in wind turbine towers that has been put into use is mainly 355MPa, and there is a lack of development and application of steel grades with a strength of 420MPa and above.

[0003] Patent CN108265226A discloses a steel for offshore wind power with a yield strength ≥460MPa and a manufacturing method. The alloy composition is designed as follows: C: 0.14~0.19%, Si: 0.31~0.45%, Mn: 1.25~1.55%, P≤0.015%, S≤0.008%, Als: 0.015~0.025%, Nb: 0.030~0.055%, V: 0.065~0.095%, Ti: 0.025~0.045%, Ni: 0.21~0.41%, Mo: 0.15~0.30%, and satisfies 0.15%≤Nb+V+Ti+0.4Als≤0.18%, 1.11%≤1.5Ni+3.3Mo≤1.31%. The yield strength of the steel plate produced by the TMCP process is ≥460MPa, the tensile strength is 550-720MPa, the elongation is ≥25%, the impact energy at -40℃ is ≥230J, and the CTOD value at -40℃ is ≥1.15mm. Although the patent protects the high plasticity and toughness of the steel plate, the alloy composition of the steel plate is high, resulting in a high cost of the product. In addition, the reduction rate of the last pass in the controlled rolling stage is ≥38%, which requires high rolling force of the equipment.

[0004] Patent CN112746158A discloses a low-cost, high crack arrest and high weldability YP460MPa grade thick steel plate and its manufacturing method, which is based on low C-low Si-medium-high Mn-Nb low alloy steel, and the specific alloy composition is designed as follows: C: 0.050-0.090%, Si: 0.01-0.10%, Mn: 1.40-1.70%, P: ≤0.013%, S≤0.0030%, Cu≤0.30%, Ni: 0.10-0.35%, Mo≤0.15%, Nb: 0.010-0.030%, Ti: 0.008-0.015%, B: 0.0015-0.0030%, N: 0.0050-0.0080%, Al≤0.010%, Ca: 0.0010-0.0030%, and the balance is Fe and unavoidable impurities. The microstructure of the steel plate is uniform and fine ferrite + dispersed bainite. The thickness of the steel plate is ≥80mm, the yield strength is ≥460MPa, the tensile strength is ≥570MPa, the impact energy value at -50℃ is ≥100J, and the fracture toughness at -20℃ is ≥6kN / mm 3 / 2 The patent protects the steel plate with good strength, plasticity and low temperature fracture toughness, but has high requirements on the content of alloy elements and process parameters of the steel plate, which must meet the following conditions: Mn / C ≥ 17, (%C) × [1 + 1.72 (%Mn) + 6.17 (%P) 1 / 2 +11.36(%P) 1 / 2 ]≤0.52, 0.20≤B / N≤0.40, Ca treatment and Ca / S ratio controlled between 1.0 and 3.0, and (%Ca)×(%S) 0.28 ≤1.0×10 -3 , accelerated cooling stop temperature T 停冷 =400-0.75t, unit is ℃, where t is the thickness of the finished steel plate. It is difficult to control in the actual industrial production of steel plates, which is not conducive to large-scale promotion.

[0005] Although the above-mentioned invention patents involve steel plates with a strength of 460MPa and some of their production methods with high performance indicators, the micro-alloy element content and some production process parameters require high control precision, and the production is difficult. In addition, wind power steel plates need to be welded when used, but the existing invention patents do not consider the weldability of the steel plates and the performance of the welded joints when designing the composition. Therefore, in response to the current demand for upgrading steel plates for wind turbine towers, the alloy composition of 460MPa-grade wind power steel plates is redesigned. On the basis of meeting the standards, by reducing the carbon content of the steel plates and controlling the production process parameters, while ensuring the strength and toughness of wind power steel, the weldability of the steel plates and the performance of the welded joints are improved, which has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0006] In view of this, the purpose of the present invention is to provide a 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest performance and a production method thereof. Through the component design of low carbon equivalent and low crack sensitivity coefficient, supplemented by the TMCP process, a low-cost, high-strength, high-crack arrest performance and excellent welding performance wind power steel plate is successfully prepared to meet the development needs of large-scale wind turbines in inland areas with harsh environments such as deserts, Gobi and wastelands, as well as deep-sea and ocean-going wind turbines, and can achieve industrial mass production with stable performance.

[0007] The present invention provides a 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest resistance, comprising the following alloy components in percentage by mass:

[0008] C: 0.08~0.12%;

[0009] Si: 0.20~0.25%;

[0010] Mn: 1.50~1.70%;

[0011] Cr: 0.25~0.35%;

[0012] Nb+V+Ti: 0.05~0.06%;

[0013] Ni: 0.15-0.35%;

[0014] Als: 0.02~0.045%;

[0015] Cu: 0.01~0.02%;

[0016] Mo: 0.003~0.005%;

[0017] The rest is Fe and inevitable impurities.

[0018] Preferably, the 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest performance has a Ceq<0.46% and a Pcm<0.21%.

[0019] Preferably, the microstructure of the 460MPa-grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest resistance is mainly composed of quasi-polygonal or acicular ferrite grains, and the average grain size is less than 6 μm.

[0020] Preferably, the 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest performance has a thickness of 20mm to 40mm, a yield strength of ≥460MPa, a tensile strength of 540MPa to 700MPa, an elongation after fracture of ≥17%, an impact energy of -40℃ ≥200J, and a CTOD characteristic value of -40℃>0.45mm.

[0021] Preferably, the 460MPa grade wind power steel with high toughness, low temperature resistance and excellent crack arrest performance has a stress ratio of 0.5 and a cycle of 10 7 The fatigue strength under certain conditions is >600MPa, and the critical crack length of the structure when fatigue failure occurs is >25mm.

[0022] Preferably, after SAW welding of the 460MPa-grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest resistance, the tensile strength of the welded joint is ≥670MPa, and the impact energy of the welding heat affected zone at -40°C is ≥100J.

[0023] The present invention also provides a method for producing the 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent anti-cracking performance as described in the above technical solution, comprising the following steps:

[0024] The alloy components are smelted, continuously cast, heated, rolled and cooled in sequence to obtain 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest performance.

[0025] Preferably, the heated ingot has a thickness of 100 mm to 300 mm, a holding temperature of 1150° C. to 1210° C., and a furnace time of 245 min to 255 min.

[0026] Preferably, the thickness of the rolled intermediate billet is 50 mm to 150 mm, the start temperature of the finishing rolling is 890° C. to 950° C., the final rolling temperature is 850° C. to 890° C., and the total number of finishing rolling passes is 6 to 10 times.

[0027] Preferably, the thickness of the cooled finished product is 10 mm to 50 mm, the start cooling temperature is 780°C to 800°C, and the final cooling temperature is 600°C to 620°C.

[0028] The invention provides a 460MPa-level wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest resistance and a production method thereof. The steel comprises the following alloy components in percentage by mass: C: 0.08-0.12%; Si: 0.20-0.25%; Mn: 1.50-1.70%; Cr: 0.25-0.35%; Nb+V+Ti: 0.05-0.06%; Ni: 0.15-0.35%; Als: 0.02-0.045%; Cu: 0.01-0.02%; Mo: 0.003-0.005%; the rest is Fe and unavoidable impurities. Compared with the prior art, the present invention successfully prepares low-cost, high-strength and high-toughness steel plates for wind power generation with high crack arrest performance and excellent welding performance through the design of components with low carbon equivalent and low crack sensitivity coefficient, supplemented by the TMCP process. It meets the development needs of large-scale wind turbines in inland areas with harsh environments such as deserts, Gobi and wastelands, as well as deep-sea and ocean-going wind turbines, and can achieve industrial mass production with stable performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The microstructure morphology of the 20 mm thick 460 MPa grade steel plate for wind power generation in Example 1;

[0030] Figure 2 The fracture morphology of the 20 mm thick 460 MPa grade wind power steel plate -40°C impact specimen of Example 1;

[0031] Figure 3 The fracture morphology of the 20 mm thick 460 MPa grade wind power steel plate -40°C CTOD sample of Example 1;

[0032] Figure 4 This is the fracture morphology of the fatigue specimen of the 20 mm thick 460 MPa grade steel plate for wind power generation in Example 1;

[0033] Figure 5 The fracture morphology of the -40°C impact specimen of the 20mm thick 460MPa grade wind power steel plate welding heat affected zone of Example 1;

[0034] Figure 6 The microstructure morphology of the 40 mm thick 460 MPa grade steel plate for wind power generation in Example 2;

[0035] Figure 7 The fracture morphology of the -40°C impact specimen of the 40mm thick 460MPa grade wind power steel plate of Example 2;

[0036] Figure 8 The fracture morphology of the 20 mm thick 460 MPa grade wind power steel plate -40°C CTOD sample of Example 2;

[0037] Fig. 9 This is the fracture morphology of the fatigue specimen of the 40mm thick 460MPa grade wind power steel plate of Example 2;

[0038] Fig.10 This is the fracture morphology of the -40°C impact specimen of the 40mm thick 460MPa grade wind power steel plate welding heat affected zone of Example 2. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The present invention provides a 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest resistance, comprising the following alloy components in percentage by mass:

[0041] C: 0.08~0.12%;

[0042] Si: 0.20~0.25%;

[0043] Mn: 1.50~1.70%;

[0044] Cr: 0.25~0.35%;

[0045] Nb+V+Ti: 0.05~0.06%;

[0046] Ni: 0.15-0.35%;

[0047] Als: 0.02~0.045%;

[0048] Cu: 0.01~0.02%;

[0049] Mo: 0.003~0.005%;

[0050] The rest is Fe and unavoidable impurities;

[0051] Preferably:

[0052] C: 0.09~0.10%;

[0053] Si: 0.20~0.22%;

[0054] Mn: 1.60~1.66%;

[0055] Cr: 0.32~0.35%;

[0056] Nb+V+Ti: 0.056~0.058%;

[0057] Ni: 0.17-0.20%;

[0058] Als: 0.03~0.04%;

[0059] Cu: 0.01%;

[0060] Mo: 0.003~0.004%;

[0061] The rest is Fe and inevitable impurities.

[0062] In order to meet the current development needs of large-scale wind turbines and the upgrading and transformation of wind farms with a single unit capacity of <1.5 MW, the present invention first starts with the composition design of the steel plate, adopts a low C and low Si composition design, and controls the content of micro-alloy elements such as Nb, V and Ti, see the above alloy composition and percentage.

[0063] In the present invention, the Ceq (carbon equivalent) of the 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest performance is preferably <0.46%, Ceq=C+Mn / 6+Si / 24+Ni / 40+Mo / 4+V / 14; the Pcm (crack sensitivity coefficient) is preferably <0.21%, Pcm=C+Si / 30+(Mn+Cu+Cr) / 20+Ni / 60+Mo / 15+V / 10.

[0064] In the present invention, the microstructure of the 460MPa grade wind power steel with high toughness, low temperature resistance and excellent crack arrest performance is preferably dominated by quasi-polygonal or acicular ferrite grains, and the average grain size is preferably below 6 μm.

[0065] In the present invention, the thickness of the 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest performance is preferably 20mm to 40mm, specifically 20mm, 30mm, or 40mm.

[0066] In the present invention, the yield strength of the 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest performance is preferably ≥460MPa, the tensile strength is preferably 540MPa-700MPa, the elongation after fracture is preferably ≥17%, the impact energy at -40°C is preferably ≥200J, and the -40°C CTOD characteristic value is preferably >0.45mm.

[0067] In the present invention, the 460MPa grade wind power steel with high toughness, low temperature resistance and excellent crack arrest performance has a stress ratio of 0.5 and a cycle of 10 7 The fatigue strength under certain conditions is preferably >600MPa, and the critical crack length of the tissue when fatigue failure occurs is preferably >25mm.

[0068] In the present invention, the welding process of the 460MPa-grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest performance does not require preheating, and the SAW welding heat input can achieve ≥16kJ / cm. After SAW welding, the tensile strength of the welded joint is preferably ≥670MPa, and the impact energy of the welding heat affected zone at -40°C is preferably ≥100J.

[0069] The present invention also provides a method for producing the 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent anti-cracking performance as described in the above technical solution, comprising the following steps:

[0070] The alloy components are smelted, continuously cast, heated, rolled and cooled in sequence to obtain 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest performance.

[0071] The invention adopts controlled rolling and controlled cooling process to shorten the production process flow. The microstructure of the prepared steel plate is mainly composed of quasi-polygonal or acicular ferrite grains. The plate thickness is 20mm-40mm, the yield strength is ≥460MPa, the tensile strength is 540MPa-700MPa, the elongation after fracture is ≥17%, the impact energy at -40℃ is ≥200J, the CTOD characteristic value at -40℃ is >0.45mm, the stress ratio is 0.5, the cycle is 10 7 Under the above conditions, the fatigue strength of the steel plate is >600MPa, and the critical crack length of the steel plate structure when fatigue failure occurs is >25mm; after SAW welding, the tensile strength of the steel plate welded joint is ≥670MPa, and the impact energy of the welding heat affected zone at -40℃ is ≥100J.

[0072] The present invention has no special restrictions on the smelting and continuous casting process, and the technical means for making alloy components into ingots well known to those skilled in the art can be used.

[0073] The main processes for producing steel plates of the present invention include: a heating process (i.e. heating of the ingot), a controlled rolling process and a controlled cooling process (i.e. controlled rolling and controlled cooling), wherein the controlled rolling process is divided into two stages of rolling, namely a rough rolling process and a finishing rolling process.

[0074] In the present invention, the thickness of the heated ingot is preferably 100 mm to 300 mm, more preferably 200 mm. During the heating treatment of the ingot, in order to ensure complete austenitization, the holding temperature is preferably 1150°C to 1210°C, more preferably 1198°C to 1206°C, and the time in the furnace is preferably 245min to 255min, more preferably 249min to 252min.

[0075] In the present invention, the thickness of the rolled intermediate billet is preferably 50 mm to 150 mm, more preferably 80 mm to 110 mm, in the finishing rolling process, the finishing rolling start temperature is preferably 890°C to 950°C, more preferably 897°C to 948°C, the final rolling temperature is preferably 850°C to 890°C, more preferably 862°C to 886°C, and the total number of finishing passes is preferably 6 to 10, more preferably 7 to 9. The present invention fully rolls in the austenite non-recrystallization zone to refine the original austenite grains, thereby obtaining uniform and fine ferrite grains and improving the comprehensive performance of the steel plate.

[0076] In the present invention, the thickness of the cooled finished product is preferably 10 mm to 50 mm, more preferably 20 mm to 40 mm, and the start cooling temperature of the controlled cooling process after rolling is preferably 780° C. to 800° C., more preferably 790° C. to 793° C., and the final cooling temperature is preferably 600° C. to 620° C., more preferably 609° C. to 618° C. A higher start cooling temperature can slow down the enrichment of carbon elements inside the original austenite grains, reduce the proportion of bainite in the final microstructure, and avoid the occurrence of local mixed crystals.

[0077] The invention provides a 460MPa-level wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest resistance and a production method thereof. The steel comprises the following alloy components in percentage by mass: C: 0.08-0.12%; Si: 0.20-0.25%; Mn: 1.50-1.70%; Cr: 0.25-0.35%; Nb+V+Ti: 0.05-0.06%; Ni: 0.15-0.35%; Als: 0.02-0.045%; Cu: 0.01-0.02%; Mo: 0.003-0.005%; the rest is Fe and unavoidable impurities. Compared with the prior art, the present invention successfully prepares low-cost, high-strength and high-toughness steel plates for wind power generation with high crack arrest performance and excellent welding performance through the design of components with low carbon equivalent and low crack sensitivity coefficient, supplemented by the TMCP process. It meets the development needs of large-scale wind turbines in inland areas with harsh environments such as deserts, Gobi and wastelands, as well as deep-sea and ocean-going wind turbines, and can achieve industrial mass production with stable performance.

[0078] In order to further illustrate the present invention, the following examples are provided for detailed description.

[0079] Example 1

[0080] The thickness of the 460MPa grade wind power steel plate with high strength, toughness and excellent low temperature crack arrest performance in this embodiment is 20mm, and its chemical composition and percentage are shown in Table 1.

[0081] The production method of the 460MPa grade wind power steel plate with high strength, toughness and excellent low temperature crack arrest performance in this embodiment includes smelting, continuous casting, heating, rolling and cooling processes, wherein the specific parameters of the heating, rolling and cooling processes are as follows:

[0082] (1) Heating process: ingot thickness 200 mm, holding temperature 1206 °C, furnace time 252 min;

[0083] (2) Rolling process: intermediate billet thickness 80 mm, finishing rolling start temperature 948 °C, final rolling temperature 886 °C, total finishing rolling passes 7 times;

[0084] (3) Cooling process: finished product thickness 20 mm, initial cooling temperature 793 °C, final cooling temperature 618 °C.

[0085] The microstructure of the high-strength and tough 460MPa grade wind power steel plate prepared in this embodiment at 1 / 2 thickness (core) is as follows: Figure 1 As shown in the figure, it can be seen that the microstructure is mainly composed of quasi-polygonal and acicular ferrite grains, with an average grain size of 4.76 μm. The various mechanical properties of the steel plate are shown in Table 2. The fracture morphology of the standard V-shaped impact specimen of the -40℃ steel plate is shown in Figure 2Based on GB / T21143-2014 "Uniform test method for quasi-static fracture toughness of metallic materials", a three-point bending specimen was used to measure the characteristic value of the crack tip extension displacement (CTOD) of the steel plate at -40°C. The experimental parameters are shown in Table 3. The CTOD fracture morphology is shown in Figure 3 As shown. Stress ratio 0.5, cycle 10 7 The fatigue strength under the condition is 620MPa, and the fracture morphology of the fatigue specimen is as follows Figure 4 The flexibility method is used to determine the critical crack length of the steel plate when fatigue occurs. The specific formula is:

[0086]

[0087] Where P i is the load size, B is the specimen thickness, and B N is the thickness of the specimen after processing, B is taken, W is the width of the specimen, a i The critical fatigue crack length of the 20mm thick steel plate when fatigue occurs is 29.1mm. The steel plate is welded by SAW welding, with a welding heat input of 20kJ / cm, no preheating, a single V-shaped groove, and a weld layer / weld pass ratio of 6 / 2. The tensile strength of the joint after welding is 688MPa, the impact energy of the heat affected zone at -40℃ is 163J, and the fracture morphology of the impact specimen is as follows Figure 5 shown.

[0088] Example 2

[0089] The thickness of the 460MPa grade wind power steel plate with high strength, toughness and excellent low temperature crack arrest performance in this embodiment is 40mm, and its chemical composition and percentage are shown in Table 1.

[0090] The production method of the 460MPa grade wind power steel plate with high strength, toughness and excellent low temperature crack arrest performance in this embodiment includes smelting, continuous casting, heating, rolling and cooling processes, wherein the specific parameters of the heating, rolling and cooling processes are as follows:

[0091] (1) Heating process: ingot thickness 200 mm, holding temperature 1198 °C, furnace time 249 min;

[0092] (2) Rolling process: intermediate billet thickness 110 mm, finishing rolling start temperature 897 °C, final rolling temperature 862 °C, finishing rolling total 9 passes;

[0093] (3) Cooling process: finished product thickness 40 mm, initial cooling temperature 790 °C, final cooling temperature 609 °C.

[0094] The microstructure of the high-strength and tough 460MPa grade wind power steel plate prepared in this embodiment at 1 / 2 thickness (core) is as follows: Figure 6As shown in the figure, it can be seen that the microstructure is mainly composed of quasi-polygonal and acicular ferrite grains, with an average grain size of 5.65 μm. The mechanical properties of the steel plate are shown in Table 2. The fracture morphology of the standard V-shaped impact specimen of the -40℃ steel plate is shown in Figure 7 Based on GB / T 21143-2014 "Uniform test method for quasi-static fracture toughness of metallic materials", a three-point bending specimen was used to measure the characteristic value of the crack tip extension displacement (CTOD) of the steel plate at -40°C. The experimental parameters are shown in Table 3. The CTOD fracture morphology is shown in Figure 8 As shown. Stress ratio 0.5, cycle 10 7 The fatigue strength under the condition is 620MPa, and the fracture morphology of the fatigue specimen is as follows Fig. 9 The flexibility method is used to determine the critical crack length of the steel plate when fatigue occurs. The specific formula is:

[0095]

[0096] Where P i is the load size, B is the specimen thickness, and B N is the thickness of the specimen after processing, B is taken, W is the width of the specimen, a i The critical fatigue crack length of the 40mm thick steel plate is 26.5mm when fatigue occurs. The steel plate is welded by SAW welding, with a welding heat input of 25kJ / cm, no preheating, a single V-shaped groove, and a weld layer / weld pass ratio of 17 / 2. The tensile strength of the joint after welding is 673MPa, the impact energy of the heat affected zone at -40℃ is 122J, and the fracture morphology of the impact specimen is as follows: Fig.10 shown.

[0097] Table 1 Chemical composition and percentage (wt%) of 460MPa grade wind power steel plate with high strength, toughness and excellent low temperature crack arrest performance provided by Examples 1 to 2

[0098] C Si Mn P S Cr Cu Ni Nb+V+Ti Mo Als Example 1 0.10 0.20 1.66 0.008 0.003 0.35 0.01 0.17 0.058 0.003 0.040 Example 2 0.09 0.22 1.60 0.010 0.002 0.32 0.01 0.20 0.056 0.004 0.030

[0099] Table 2 Mechanical properties of 460MPa grade wind power steel plates with high strength and toughness and excellent low temperature crack arrest performance provided by Examples 1 to 2

[0100]

[0101]

[0102] Table 3 -40℃ CTOD characteristic value parameters of 460MPa grade wind power steel plate with high strength, toughness and excellent low temperature crack arrest performance provided by Examples 1 and 2

[0103] B / mm W / mm <![CDATA[a0 / mm]]> Fmax / kN <![CDATA[V p / mm]]> <![CDATA[δ m / mm]]> Example 1 10 20 10.02 11.28 2.45 0.46 Example 2 10 20 10.65 10.26 2.79 0.50

[0104] Note: B is the specimen thickness, W is the specimen width, a0 is the initial crack length, Fmax is the maximum force before fracture, V p is the plastic component of the notch opening displacement, δ m is the CTOD value for stable crack extension.

[0105] The experimental results show that:

[0106] Compared with steel plates of the same strength level, the product provided by the present invention has the following beneficial effects:

[0107] (1) The carbon content of the steel plate is reduced to 0.08-0.12%, and 0.25-0.35% of Cr is added, which increases the hardenability and uniformity of the structure of the 460MPa wind power steel plate along the thickness direction;

[0108] (2) Through the composition design of low carbon equivalent and welding crack sensitivity index, and matching the corresponding TMCP process, a steel plate with quasi-polygonal or acicular ferrite grains is prepared. While having high strength, excellent low-temperature toughness and crack arrest performance, the welding performance of the steel plate is also excellent. The tensile strength of the joint after SAW welding is ≥670MPa, and the impact energy of the welding heat affected zone at -40℃ is ≥100J;

[0109] (3) By adding the element Cr and a small amount of precious alloying element Cu, the corrosion resistance of wind power steel in humid service environments such as deep sea and ocean is improved.

[0110] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest performance, comprising the following alloy components in percentage by mass: C：0.08～0.12％； Si: 0.20-0.25%; Mn: 1.50~1.70%; Cr：0.25～0.35％； Nb+V+Ti: 0.05~0.06%; Ni: 0.15-0.35%; Als: 0.02~0.045%; Cu: 0.01~0.02%; Mo: 0.003~0.005%; The rest is Fe and inevitable impurities.

2. The 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest performance according to claim 1 is characterized in that: The Ceq of steel is <0.46%, and Pcm is <0.21%.

3. The 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest performance according to claim 1, characterized in that: The microstructure of the steel is mainly composed of quasi-polygonal or acicular ferrite grains, with an average grain size of less than 6 μm.

4. The 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest performance according to claim 1, characterized in that: The thickness of the steel is 20 mm to 40 mm, the yield strength is ≥460 MPa, the tensile strength is 540 MPa to 700 MPa, the elongation after fracture is ≥17%, the impact energy at -40°C is ≥200 J, and the CTOD characteristic value at -40°C is >0.45 mm.

5. The 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest performance according to claim 1, characterized in that: Steel at stress ratio 0.5, cycle 10 7 The fatigue strength under certain conditions is >600MPa, and the critical crack length of the tissue when fatigue failure occurs is >25mm.

6. The 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent crack arrest performance according to claim 1, characterized in that: After SAW welding, the tensile strength of the welded joint is ≥670MPa, and the impact energy of the welding heat affected zone at -40℃ is ≥100J.

7. A method for producing the 460MPa grade wind power steel with high strength, toughness, low temperature resistance and excellent anti-cracking performance as claimed in any one of claims 1 to 6, comprising the following steps: The alloy components are smelted, continuously cast, heated, rolled and cooled in sequence to obtain the product.

8. The production method according to claim 7, characterized in that: The thickness of the heated ingot is 100 mm to 300 mm, the insulation temperature is 1150° C. to 1210° C., and the time in the furnace is 245 min to 255 min.

9. The production method according to claim 7, characterized in that: The thickness of the rolled intermediate billet is 50 mm to 150 mm, the start temperature of the finishing rolling is 890° C. to 950° C., the final rolling temperature is 850° C. to 890° C., and the total number of finishing rolling passes is 6 to 10 times.

10. The production method according to claim 7, characterized in that: The thickness of the cooled finished product is 10 mm to 50 mm, the start cooling temperature is 780° C. to 800° C., and the final cooling temperature is 600° C. to 620° C.

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