CN118166269A - Low-temperature-resistant steel for offshore wind power flange, heat treatment method and production method thereof - Google Patents
Low-temperature-resistant steel for offshore wind power flange, heat treatment method and production method thereof Download PDFInfo
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- CN118166269A CN118166269A CN202410227751.0A CN202410227751A CN118166269A CN 118166269 A CN118166269 A CN 118166269A CN 202410227751 A CN202410227751 A CN 202410227751A CN 118166269 A CN118166269 A CN 118166269A
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- 239000010959 steel Substances 0.000 title claims abstract description 118
- 238000010438 heat treatment Methods 0.000 title claims abstract description 39
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- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 16
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- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 11
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 10
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 9
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 8
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 7
- 238000005452 bending Methods 0.000 claims abstract description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 14
- 238000005496 tempering Methods 0.000 claims description 11
- 238000001816 cooling Methods 0.000 claims description 7
- 238000010791 quenching Methods 0.000 claims description 7
- 230000000171 quenching effect Effects 0.000 claims description 7
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- 238000010891 electric arc Methods 0.000 claims description 3
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- 229910052742 iron Inorganic materials 0.000 claims description 2
- 238000005728 strengthening Methods 0.000 description 15
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Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
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- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
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Abstract
The invention discloses low-temperature-resistant steel for a marine wind power flange, a heat treatment method and a production method thereof, wherein the steel for the marine wind power flange comprises ：C 0.05％～0.10％、Si 0.20％～0.40％、Mn 1.70％～2.00％、Cr 0.30％～0.60％、Mo 0.10％～0.30％、Ni 0.40％～0.60％、Cu 0.030％～0.050％、V 0.10％～0.20％、Ti 0.015％～0.035％、B 0.0020％～0.0040％、Al 0.015％～0.025％、N 0.0050％～0.0090％, parts by weight of steel with the yield strength grade of Q420NE, and has the advantages of good low-temperature toughness, rotational bending fatigue strength and excellent corrosion resistance.
Description
Technical Field
The invention belongs to the technical field of steel, and particularly relates to low-temperature-resistant steel for an offshore wind power flange, a heat treatment method and a production method thereof.
Background
The offshore wind power has the characteristics of cleanness and high efficiency, and is a development trend of wind power in the future. The installed capacity and the installed power of wind power in China are increased year by year, the land wind power installation gradually tends to be saturated, and the offshore wind power enters a rapid growth period. Offshore wind power is developed to high power and deep sea, and the performance requirement on key wind power supporting components is improved. The wind power flange is an important supporting piece and a connecting piece of the wind power tower, and the performance of the flange is related to the safety of wind power.
With the increase of the offshore wind power and the deep water, the diameter and the height of a wind power tower are increased, and in order to reduce the weight of the wind power tower, the strength of steel for the tower is improved, and the grade is currently commonly used as grade S355 NL. The strength level of steel used for the wind power tower in the future is improved to Q390 and Q420, and the flange is used as an important component of the tower, so that the strength level is correspondingly improved. At present, in order to solve the problem of offshore wind power support in China, the thickness of the wall of a tower is increased to increase the support strength. The research on steel for the high-strength wind power flange is relatively less, and the requirement for developing the high-strength offshore wind power flange is increasingly urgent in order to reduce the weight of the tower.
The patent CN 111893394a refers to a manufacturing process of a flange of an offshore wind power foundation pile, and emphasizes the processes of forging, ring rolling and heat treatment of the flange, and the strength grade of flange steel is 355 grade. The improvement of the strength of the steel is not explicitly described, the improvement of the low temperature toughness is not explicitly described, and the product toughness is not mentioned in the examples.
Patent CN 111286668A indicates a low-cost high-low-temperature toughness rare earth wind power flange steel and a production process thereof, and the patent shows that the stated patent focuses on adopting rare earth treatment to improve the low-temperature toughness of the steel at minus 60 ℃, and the strength grade of the steel is Q345 grade. The strength level of this patent is still insufficient.
The patent CN 110773692A indicates a forging method of a low-temperature high-strength offshore wind power flange, the carbon content of the flange steel listed in the patent is up to 3.7 percent, the carbon content of the flange steel exceeds that of common steel, and the system is a cast iron system and has low-temperature toughness. And the patent does not enumerate examples, no final product performance data exists, and the strength grade and toughness of the product are unknown.
Patent CN 1115058645A indicates a continuous casting round billet for a wind power large-wall-thickness low-cost low-Wen Datong flange and a manufacturing method thereof. The yield strength of the steel designed by the patent is 285MPa, the maximum impact energy at 50 ℃ below zero is 168J, and the strength and the toughness can not meet the requirements of offshore wind power flanges. In addition, the large wall thickness of the patent title, the wall thickness magnitude is not present in the patent.
Patent CN 113913690a indicates a steel for a wind power flange at sea and a preparation method thereof, and the patent proposes a method for manufacturing the steel for the wind power flange with the yield strength of 460MPa level, but the low-temperature toughness of the steel is insufficient, and the offshore fatigue performance of the flange is not involved.
The patent CN 114921720A indicates a steel ingot for a flange of a high-power offshore wind turbine with the power of more than six megawatts and a production method thereof, and the strength of the flange designed by the patent is Q355 level, and the toughness at low temperature is insufficient. The raw materials are steel ingots, the utilization rate of the materials is not high, and the cost is high.
Patent CN 112342459a indicates a low Wen Fengdian resistant steel for flanges and a rolling method thereof, and the strength of the flange designed by the patent is Q355 level, and the toughness at low temperature is not enough.
Therefore, according to the requirements of the offshore wind power flange, the steel for the flange which is low-temperature resistant, high-strength, high-fatigue resistant and corrosion resistant is developed, and the heat treatment process of the flange is designed in a targeted manner, so that the safety problem of large-scale and deep-sea offshore unit equipment is solved.
Disclosure of Invention
In order to solve the technical problems, the invention provides the steel for the low-temperature-resistant offshore wind power flange, the heat treatment method and the production method thereof, and the steel has the yield strength grade of Q420NE, good low-temperature toughness, rotational bending fatigue strength and excellent corrosion resistance.
The technical scheme adopted by the invention is as follows:
The low temperature resistant steel for the offshore wind power flange contains ：C 0.05％～0.10％、Si0.20％～0.40％、Mn 1.70％～2.00％、Cr 0.30％～0.60％、Mo 0.10％～0.30％、Ni0.40％～0.60％、Cu 0.030％～0.050％、V 0.10％～0.20％、Ti 0.015％～0.035％、B0.0020％～0.0040％、Al 0.015％～0.025％、P≤0.015％、S≤0.010％、N 0.0050％～0.0090％、O≤0.0040％, the balance of Fe and other unavoidable impurities in percentage by weight.
The components of the low-temperature-resistant steel for the offshore wind power flange meet the following conditions:
A＝(4.5×％C)×(1+3.4×％Mn)×(1+0.7×％Si)×(1.2+2.6×％Cu)×(1+2.7×％Ni)×(1+3.
1×％Cr)×(1+2.3×％Mo)×(1+1.6×％V+4.6×％N+1.3×％Ti+1.7×％Cu)；
40.0≤A≤55.0。
The components of the low-temperature-resistant steel for the offshore wind power flange meet the following conditions: y=2.5× cr+3.8× mo+16.5× ni+2.5× cu+1.2× v+1.4× Ti-1× C-4× Mn > 2.0.
The metallographic structure of the low-temperature-resistant steel for the offshore wind power flange is tempered sorbite.
The wall thickness of the low-temperature-resistant offshore wind power flange is more than or equal to 240mm.
The yield strength grade of the low-temperature-resistant steel for the offshore wind power flange is Q420NE grade; low temperature toughness at the wall thickness of 1/2 is minus 50 ℃ KV 2 is more than or equal to 210J; the rotational bending fatigue strength is more than or equal to 300MPa; the room temperature corrosion rate is less than or equal to 0.09mm/a.
The invention also provides a heat treatment method of the steel for the low-temperature-resistant offshore wind power flange, which comprises the steps of quenching and tempering.
The quenching conditions are as follows: heating the flange semi-finished product to the temperature of T 1 =800-900 ℃, preserving heat for T 1 min, and then cooling with water, wherein S-T 1/10≤t1≤S-T1/50, S is the wall thickness of the flange, and the unit is mm. The furnace charging temperature of the flange semi-finished product is less than or equal to 400 ℃.
The tempering conditions are as follows: heating the flange semi-finished product to the temperature of T 2 =600-700 ℃, preserving heat for T 2 min, and then cooling with water, wherein 1.5×S-T 2/10≤t2≤1.5×S-T2/50, S is the flange wall thickness, and the unit is mm.
The invention also provides a production method of the low-temperature-resistant offshore wind power flange steel, which comprises the following steps: smelting in an electric arc furnace or a converter, refining in an LF furnace, RH or VD vacuum degassing, round billet continuous casting, round billet slow cooling, round billet blanking, round billet heating, upsetting, punching, ring rolling, heat treatment, machining, flaw detection, grinding, packaging and warehousing; the heat treatment is carried out by adopting the heat treatment method.
The invention provides low-temperature-resistant steel for offshore wind power flanges, which comprises the following components in parts by weight:
C: c is the least expensive strengthening element in the steel, and each 0.01% of solid solution C can improve the strength by about 45MPa, and the C and the alloy element in the steel form a precipitated phase to play a role in precipitation strengthening. And C can obviously improve the hardenability, so that the center of the steel pipe with large wall thickness can obtain a martensitic structure. However, as the content increases, the plasticity and toughness decrease, so the C content is controlled to be 0.05-0.10%.
Si: si is an effective solid solution strengthening element in steel, improves the strength and the hardness of the steel, can play a deoxidizing role in steelmaking, and is a common deoxidizer. However, si tends to be biased to have austenite grain boundaries, so that the bonding force of the grain boundaries is reduced, and brittleness is induced. In addition, si tends to cause element segregation in steel. Therefore, the Si content is controlled to be 0.20% to 0.40%.
Mn: mn can play a solid solution strengthening role, the solid solution strengthening capability is weaker than that of Si, mn is an austenite stabilizing element, the hardenability of steel can be obviously improved, decarburization of steel can be reduced, and the combination of Mn and S can prevent hot shortness caused by S. However, excessive Mn reduces the plasticity of the steel. Therefore, the Mn content is controlled to be 1.70-2.00%.
Cr: cr is a carbide forming element, and Cr can improve both hardenability and strength of steel, but is liable to cause temper embrittlement. Cr can improve the oxidation resistance and corrosion resistance of steel, but when the Cr content is too high, crack sensitivity is increased. The Cr content should be controlled to be 0.30% -0.60%.
Mo: mo mainly improves the hardenability of steel, and Mo solid-dissolved in a matrix can keep higher stability of a steel structure in the tempering process, and can effectively reduce the segregation of P, S, as and other impurity elements at a grain boundary, so that the toughness of the steel is improved, and the tempering brittleness is reduced. Mo decreases the stability of M 7C3, and needle-like Mo 2 C is formed when the Mo content is higher, resulting in a decrease in the Mo content of the matrix. Mo can improve the strength of steel by the combined action of solid solution strengthening and precipitation strengthening, and can also change the toughness of steel by changing the precipitation of carbide. So that the Mo content is controlled to be 0.10-0.30%.
Ni: ni can form infinite mutual-soluble solid solution with Fe, is an austenite stabilizing element, has the effect of expanding a phase area, increases the stability of supercooled austenite, makes a C curve move right, and improves the hardenability of steel. Ni can refine the width of the martensite lath and improve the strength. Ni can obviously reduce the ductile-brittle transition temperature of steel and improve the low-temperature toughness. The Ni element is a noble metal element, and excessive addition results in excessive cost. The Ni content is controlled to be 0.40% -0.60%.
V: v is a strong C, N compound forming element, and V (C, N) is finely dispersed and maintains a coherent relation with the matrix, so that the effects of strengthening and refining tissues can be achieved. The V content is controlled to be 0.10-0.20%.
Ti: ti is a strong C, N compound forming element, ti (C, N) is finely dispersed and maintains a coherent relation with the matrix, so that the effect of strengthening and refining the structure can be achieved, and fatigue crack initiation and expansion resistance can be increased by strengthening the matrix, so that fatigue strength is improved. The Ti content is controlled to be 0.015-0.035%.
Cu: cu expands an austenite phase region, and a simple substance Cu can be used as a second phase to obviously improve strength, and can improve the tempering stability and strength of a structure. However, too high Cu will result in Cu embrittlement. Therefore, the Cu content is controlled to be 0.030-0.050%.
Al: al is a main deoxidizer for steelmaking, al and N are combined to form tiny dispersion-distributed AlN, and the tiny dispersion-distributed AlN and a matrix are kept in a coherent relation, so that the effects of strengthening and refining tissues can be achieved, fatigue crack initiation and expansion resistance can be increased, and the durability of the steel is improved. The Al content is controlled to be 0.015-0.025%.
O and N: T.O forms oxide inclusion in steel, and the T.O is controlled to be less than or equal to 0.0040 percent; n can form fine precipitated phase refined structure with nitride forming elements in steel, fe 4 N can be precipitated, the diffusion speed is low, the timeliness of the steel is caused, and the processing performance is reduced, so that the N is controlled to be 0.0050% -0.0090%.
According to the low-temperature-resistant offshore wind power flange steel, the strength of the steel can be improved through the addition of the beneficial alloy elements, the toughness of the steel can be improved through the effective proportion of the elements, and the fracture performance can be improved through the formation of effective toughness precipitated phases. Under the composition system, mn in alloy elements is most effective in improving hardenability and strength so that the coefficient is 3.4; mo contributes significantly to hardenability and strength by improving tempering stability and interaction with Mn, and has a coefficient of 2.3; cr is a main substitution solid solution element and a carbide forming element, and has a contribution coefficient to strength of 3.1; ni and Cu do not form carbide in steel, and the hardenability and strength of the steel are improved by changing the crystal lattice morphology through solid solution strengthening, and the coefficients are 2.7 and 2.6 respectively; c is a nonmetallic element, is the most main interstitial solid solution strengthening element in steel, has influence on strength and toughness, and has a coefficient of 4.5; si is a nonmetallic element and is also a main solid solution strengthening element in steel, and the contribution to the performance of the steel is 0.7; v, N, ti is that the microalloying elements increase the strength of the steel by interacting and forming a second phase, and N can increase the strength of the steel by changing the lattice of C, so the coefficients are 1.6, 4.6 and 1.3, respectively. Because the strength, plasticity and toughness of the steel have inverse proportion relation, and the plasticity and toughness are reduced when the strength is high, the strength cannot be improved at the same time in order to ensure the comprehensive performance of the steel. Let the strengthening factor in the steel be denoted by A 40.0≤A≤55.0,A＝(4.5×％C)×(1+3.4×％Mn)×(1+0.7×％Si)×(1.2+2.6×％Cu)×(1+2.7×％Ni)×(1+3.1×％Cr)×(1+2.3×％Mo)×(1+1.6×％V+4.6×％N+1.3×％Ti+1.7×％Cu).
The flange needs better fatigue resistance in the service process, so that the proportion of C, mn, cr, mo, ni, cu is limited. As C, mn can obviously improve the strength of steel, but the elements are easy to deviate to cause uneven structure, thereby increasing the entropy of the material and causing local weakness of the material matrix, thereby aggravating crack formation. Cr, mo and V can form a second phase with C, N in steel, and the second phase can form a fixed source of defects in the steel, so that the fatigue capacity is improved, and the fatigue resistance is beneficial. Ni can improve the stacking fault energy of steel, improve the dislocation density of steel and reduce the dislocation slip rate, thereby improving the fatigue resistance. Cu can be well combined with steel at nano scale to form a semi-coherent relation, so that the effect of fixing defects is achieved, and fatigue cracks can be prevented. The anti-fatigue factor in the steel is expressed by Y, and then Y is more than or equal to 2.0,
Y＝2.5×％Cr+3.8×％Mo+16.5×％Ni+2.5×％Cu+1.2×％V+1.4×％Ti-1×％C-4×％Mn。
According to the heat treatment method of the low-temperature-resistant offshore wind power flange steel, the heat preservation time of quenching and tempering is determined according to the wall thickness and the heating temperature of the flange, and 100% tempered sorbite tissues can be obtained after heat treatment.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the invention, each chemical component affecting the strength of steel is limited in the formula A, the A is controlled to be more than or equal to 40.0 and less than or equal to 55.0, the toughness of the steel can be improved through the effective proportion of each chemical component, and the fracture performance of the steel can be improved through the formation of effective toughness precipitated phases.
2. In order to ensure that the flange has better fatigue resistance in the service process, the invention limits C, mn, cr, mo, ni, cu components in the formula Y, and the Y is controlled to be more than or equal to 2.0.
3. The yield strength grade of the steel for the low-temperature-resistant offshore wind power flange is Q420NE grade, and the tensile strength at the 1/2 wall thickness is more than or equal to 610MPa and the yield strength is more than or equal to 440MPa; low temperature toughness at the wall thickness of 1/2 is minus 50 ℃ KV 2 is more than or equal to 210J; the rotational bending fatigue strength is more than or equal to 300MPa; the room temperature corrosion rate is less than or equal to 0.09mm/a, and the alloy has better low-temperature toughness, rotational bending fatigue strength and excellent corrosion resistance.
Drawings
FIG. 1 is a metallographic diagram of a wind power flange steel according to example 1;
FIG. 2 is a metallographic diagram of a steel for a wind power flange in comparative example 3.
Detailed Description
The invention provides low-temperature-resistant steel for a marine wind power flange, which comprises ：C0.05％～0.10％、Si 0.20％～0.40％、Mn 1.70％～2.00％、Cr 0.30％～0.60％、Mo0.10％～0.30％、Ni 0.40％～0.60％、Cu 0.030％～0.050％、V 0.10％～0.20％、Ti0.015％～0.035％、B 0.0020％～0.0040％、Al 0.015％～0.025％、P≤0.015％、S≤0.010％、N 0.0060％～0.0090％、O≤0.0040％, weight percent of Fe and other unavoidable impurities.
The components of the low-temperature-resistant steel for the offshore wind power flange meet the following conditions:
A＝(4.5×％C)×(1+3.4×％Mn)×(1+0.7×％Si)×(1.2+2.6×％Cu)×(1+2.7×％Ni)×(1+3.
1×％Cr)×(1+2.3×％Mo)×(1+1.6×％V+4.6×％N+1.3×％Ti+1.7×％Cu)；
40.0≤A≤55.0。
The components of the low-temperature-resistant steel for the offshore wind power flange meet the following conditions: y=2.5× cr+3.8× mo+16.5× ni+2.5× cu+1.2× v+1.4× Ti-1× C-4× Mn > 2.0.
The heat treatment method of the low-temperature-resistant steel for the offshore wind power flange comprises the steps of quenching and tempering.
The quenching conditions are as follows: heating the flange semi-finished product to the temperature of T 1 =800-900 ℃, preserving heat for T 1 min, and then cooling with water, wherein S-T 1/10≤t1≤S-T1/50, S is the wall thickness of the flange, and the unit is mm.
The tempering conditions are as follows: heating the flange semi-finished product to the temperature of T 2 =600-700 ℃, preserving heat for T 2 min, and then cooling with water, wherein 1.5×S-T 2/10≤t2≤1.5×S-T2/50, S is the flange wall thickness, and the unit is mm.
The production method of the steel for the low-temperature-resistant offshore wind power flange comprises the following steps of: smelting in an electric arc furnace or a converter, refining in an LF furnace, RH or VD vacuum degassing, round billet continuous casting, round billet slow cooling, round billet blanking, round billet heating, upsetting, punching, ring rolling, heat treatment, machining, flaw detection, grinding, packaging and warehousing; the heat treatment is carried out by adopting the heat treatment method.
The present invention will be described in detail with reference to examples.
The compositions and weight percentages of the steel for offshore wind turbine flanges in each of the examples and comparative examples are shown in table 1.
TABLE 1
| Steel grade | C | Si | Mn | Cr | Ni | Mo | Cu | V | Ti |
| Example 1 | 0.06 | 0.35 | 1.95 | 0.47 | 0.59 | 0.23 | 0.032 | 0.11 | 0.023 |
| Example 2 | 0.08 | 0.32 | 1.84 | 0.37 | 0.56 | 0.29 | 0.038 | 0.12 | 0.027 |
| Example 3 | 0.10 | 0.22 | 1.71 | 0.56 | 0.42 | 0.12 | 0.048 | 0.18 | 0.016 |
| Comparative example 1 | 0.08 | 0.38 | 1.94 | 0.45 | 0.41 | 0.28 | 0.042 | 0.17 | 0.025 |
| Comparative example 2 | 0.09 | 0.29 | 1.92 | 0.56 | 0.42 | 0.18 | 0.045 | 0.16 | 0.034 |
| Comparative example 3 | 0.07 | 0.34 | 1.71 | 0.38 | 0.48 | 0.23 | 0.031 | 0.13 | 0.018 |
| Steel grade | B | Al | P | S | N | O | A value | Y value | |
| Example 1 | 0.0025 | 0.019 | 0.009 | 0.009 | 0.0056 | 0.0036 | 41.23 | 4.17 | |
| Example 2 | 0.0035 | 0.020 | 0.013 | 0.007 | 0.0085 | 0.0031 | 49.68 | 4.10 | |
| Example 3 | 0.0022 | 0.023 | 0.010 | 0.009 | 0.0072 | 0.0029 | 49.71 | 2.2 | |
| Comparative example 1 | 0.0025 | 0.023 | 0.012 | 0.002 | 0.0062 | 0.0032 | 52.81 | 1.46 | |
| Comparative example 2 | 0.0028 | 0.018 | 0.008 | 0.004 | 0.0073 | 0.0026 | 56.24 | 1.58 | |
| Comparative example 3 | 0.0032 | 0.021 | 0.007 | 0.005 | 0.0064 | 0.0032 | 34.18 | 3.09 |
The production process of the steel for the offshore wind power flange comprises the following steps:
Smelting in an electric furnace: oxygen is fixed before tapping, and steel retaining operation is adopted in the tapping process, so that slag discharging is avoided;
LF furnace: C. si, mn, cr, ni, mo, V, ti, cu and other elements are adjusted to target values;
Vacuum degassing: the pure degassing time is more than or equal to 15 minutes, the H content after vacuum treatment is less than or equal to 1.5ppm, and the phenomenon of hydrogen embrittlement caused by white spots in steel is avoided;
continuous casting: the target temperature of the ladle molten steel is controlled to be 10-40 ℃ above the liquidus temperature, and round billets with the diameter of more than or equal to 700mm are continuously cast.
The manufacturing route of the flange comprises the following steps: smelting in arc furnace or converter, refining in LF furnace, vacuum degassing in RH or VD, and continuous casting of round billetSlowly cooling the round billet, blanking the round billet, heating the round billet, upsetting, punching, ring rolling, heat treatment, machining, flaw detection, grinding, packaging and warehousing.
The heat treatment methods of the steel for offshore wind turbine flanges in each example and comparative example are shown in table 2.
Table 2 list of process conditions for the examples and comparative examples of the present invention
The offshore wind power flange steel produced in each example and comparative example was subjected to performance detection according to the following method:
Tissue: sampling on 1/2 thickness of the flange for metallographic phase, grain size and hardness difference analysis.
Performance: samples were sampled at 1/2 thickness of the flange for tensile, impact, fatigue and corrosion testing, and tensile, impact and fatigue performance tests were performed with reference to GB/T228, GB/T229 and GB/T8650, respectively.
Corrosion experiment: and (3) taking corrosion samples on the thickness of 1/2 of the flange, developing the reduction of comprehensive corrosion according to the GB/T4334 standard, and measuring the corrosion rate of artificial seawater by a 720-hour immersion test of the corrosion reagent.
The mechanical properties are shown in Table 3.
TABLE 3 Table 3
From the above, the chemical composition and production method of the steel in examples 1-3 are properly controlled, the chemical composition of the steel is ensured to be less than or equal to 35.0 and less than or equal to 55.0, and Y is more than or equal to 2.0, so that the produced steel has better strength, plasticity, toughness and corrosion resistance. While the contents of the chemical components in comparative examples 1 to 3 were controlled in accordance with the required range of the present invention, 35.0.ltoreq.A.ltoreq.55.0 was not ensured, Y.ltoreq.2.0, and the heat treatment process of comparative example 2 and comparative example 3 was not reasonably controlled, resulting in excessively low strength, insufficient toughness, and unsatisfactory overall properties of the produced steels.
The foregoing detailed description of a low temperature resistant offshore wind power flange steel and heat treatment method and production method thereof has been presented with reference to examples, which are intended to be illustrative and not limiting, and several examples can be listed according to the scope defined thereby, without departing from the general inventive concept, and therefore, shall fall within the scope of protection of the present invention.
Claims (10)
1. A low-temperature-resistant steel for a marine wind power flange is characterized by comprising ：C 0.05％～0.10％、Si 0.20％～0.40％、Mn 1.70％～2.00％、Cr 0.30％～0.60％、Mo 0.10％～0.30％、Ni 0.40％～0.60％、Cu 0.030％～0.050％、V 0.10％～0.20％、Ti 0.015％～0.035％、B 0.0020％～0.0040％、Al 0.015％～0.025％、P≤0.015％、S≤0.010％、N 0.0050％～0.0090％、O≤0.0040％, weight percent of Fe and other unavoidable impurities.
2. The steel for low-temperature-resistant offshore wind turbine flanges according to claim 1, characterized in that the composition of the steel for low-temperature-resistant offshore wind turbine flanges satisfies:
A＝(4.5×％C)×(1+3.4×％Mn)×(1+0.7×％Si)×(1.2+2.6×％Cu)×(1+2.7×％Ni)×(1+3.
1×％Cr)×(1+2.3×％Mo)×(1+1.6×％V+4.6×％N+1.3×％Ti+1.7×％Cu)；
40.0≤A≤55.0。
3. the steel for low-temperature-resistant offshore wind turbine flanges according to claim 1, characterized in that the composition of the steel for low-temperature-resistant offshore wind turbine flanges satisfies: y=2.5× cr+3.8× mo+16.5× ni+2.5× cu+1.2× v+1.4× Ti-1× C-4× Mn > 2.0.
4. The steel for a low-temperature-resistant offshore wind turbine flange according to claim 1, wherein a metallographic structure of the steel for a low-temperature-resistant offshore wind turbine flange is tempered sorbite.
5. The steel for low-temperature-resistant offshore wind turbine flanges according to claim 1, wherein the wall thickness of the low-temperature-resistant offshore wind turbine flanges is not less than 240mm.
6. The low temperature resistant offshore wind turbine flange steel of claim 1, wherein the yield strength grade of the low temperature resistant offshore wind turbine flange steel is Q420NE grade; low temperature toughness at the wall thickness of 1/2 is minus 50 ℃ KV 2 is more than or equal to 210J; the rotational bending fatigue strength is more than or equal to 300MPa; the room temperature corrosion rate is less than or equal to 0.09mm/a.
7. A method for heat treatment of steel for a low temperature resistant offshore wind power flange according to any one of claims 1-6, wherein the heat treatment method comprises the steps of quenching and tempering.
8. The heat treatment method of low-temperature-resistant offshore wind power flange steel according to claim 7, wherein the quenching conditions are: heating the flange semi-finished product to the temperature of T 1 =800-900 ℃, preserving heat for T 1 min, and then cooling with water, wherein S-T 1/10≤t1≤S-T1/50, S is the wall thickness of the flange, and the unit is mm.
9. The heat treatment method of low temperature resistant offshore wind power flange steel according to claim 7, wherein the tempering condition is: heating the flange semi-finished product to the temperature of T 2 =600-700 ℃, preserving heat for T 2 min, and then cooling with water, wherein 1.5×S-T 2/10≤t2≤1.5×S-T2/50, S is the flange wall thickness, and the unit is mm.
10. A method for producing a steel for a low temperature resistant offshore wind power flange according to any one of claims 1 to 6, wherein the method comprises the steps of: smelting in an electric arc furnace or a converter, refining in an LF furnace, RH or VD vacuum degassing, round billet continuous casting, round billet slow cooling, round billet blanking, round billet heating, upsetting, punching, ring rolling, heat treatment, machining, flaw detection, grinding, packaging and warehousing; the heat treatment is carried out by the heat treatment method according to any one of claims 7 to 9.
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