CN116083809A - Steel for fine-grain wind power flange and manufacturing method thereof - Google Patents

Steel for fine-grain wind power flange and manufacturing method thereof Download PDF

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CN116083809A
CN116083809A CN202310231584.2A CN202310231584A CN116083809A CN 116083809 A CN116083809 A CN 116083809A CN 202310231584 A CN202310231584 A CN 202310231584A CN 116083809 A CN116083809 A CN 116083809A
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steel
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wind power
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王飞
曹传军
郭盛琦
王皇刚
马天坤
赵方娜
刘丹丹
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Elite Energy Equipment Co ltd
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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B22D11/111—Treating the molten metal by using protecting powders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • B22D11/18—Controlling or regulating processes or operations for pouring
    • B22D11/181—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level
    • B22D11/182—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level by measuring temperature
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • B22D11/20—Controlling or regulating processes or operations for removing cast stock
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0006—Adding metallic additives
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • 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
    • C21D1/26—Methods of annealing
    • C21D1/28—Normalising
    • 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
    • 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
    • C22C33/06—Making ferrous alloys by melting using master alloys
    • 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
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • 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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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
    • 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
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

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  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
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  • Physics & Mathematics (AREA)
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  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

The application discloses steel for a fine-grain wind power flange and a manufacturing method thereof, belonging to the technical field of ferrous metallurgy and the technical field of mechanical manufacturing. The fine-grain steel for the wind power flange comprises the following components in percentage by weight: c:0.13-0.15%, si:0.17-0.40%, mn:1.2 to 1.6 percent, P is less than or equal to 0.025 percent, S is less than or equal to 0.003 percent, and Nb:0.03-0.05%, al <0.06%, ce less than or equal to 300ppm, la less than or equal to 300ppm, H less than or equal to 2ppm, O less than or equal to 20ppm, N less than or equal to 300ppm, and the balance of Fe and unavoidable impurities. According to the invention, through microalloying, adding La rare earth elements and content ratios of other elements, on one hand, the grain size is refined through refining solidification structures of rare earth oxysulfide; on the other hand, alN is controlled to act along crystallization in the thermoforming and heat treatment processes, so that the whole-flow tissue refinement is realized, and meanwhile, the strength and the toughness of the flange are improved.

Description

Steel for fine-grain wind power flange and manufacturing method thereof
Technical Field
The application relates to steel for a fine-grain wind power flange and a manufacturing method thereof, belonging to the technical field of ferrous metallurgy and the technical field of mechanical manufacturing.
Background
Wind energy stores huge energy and is a clean renewable energy source, so wind power generation is widely paid attention to various countries (including China). The wind power flange is an important component for connecting the tower barrel, the hub and the blades, and is one of key core structural members of the wind turbine generator.
With the rapid development of the wind power generation industry, the environment of a newly built wind field site selection area is more and more severe, and the wind turbine generator is often subjected to extreme climate tests such as high cold, high humidity, sand wind, salt corrosion and the like. The quality of the flange directly determines the safety of the wind turbine against extreme weather. Therefore, the requirements of people on the wind power flange are also more and more severe, the raw materials and the processing and production processes of the wind power flange are strictly controlled, and the material performance of the flange steel is continuously improved.
Patent publication number CN107058877a discloses a method for manufacturing a wind power flange for a low-temperature environment, which comprises the following chemical components: 0.08-0.16% of C, 0.15-0.30% of Si, 1.00-1.60% of Mn, less than or equal to 0.020% of P, less than or equal to 0.015% of S, less than or equal to 0.12% of V, less than or equal to 0.05% of Nb, less than or equal to 0.50% of Ni, less than or equal to 0.20% of Cr, less than or equal to 0.25% of Cu, more than or equal to 0.015% of Als, less than or equal to 0.10% of Mo, and less than or equal to Ti: less than or equal to 0.010 percent. According to the invention, chemical components are optimized, a forging forming process and a heat treatment process are optimized, and the performance of the manufactured flange meets the low-temperature impact performance requirement of minus 60 ℃. However, the invention lacks measures for controlling the solidification structure of the steel ingot, and coarse solidification structure can inherit to the final product, so that the quality stability is affected.
Patent publication No. CN11128668A discloses a low-cost high-low-temperature toughness rare earth wind power flange steel and a production process thereof, wherein the steel comprises the following chemical components: c:0.17-0.20%, si:0.15-0.35%, mn:1.20 to 1.40 percent, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, 0.020 to 0.040 percent of Nb, less than or equal to 0.0010 percent of Ce, less than or equal to 2ppm of H, less than or equal to 0 and less than or equal to 15ppm of N and less than or equal to 60ppm. The invention reduces the addition amount of alloy, lowers the cost, improves the shape of casting blank tissue and inclusion, and improves the low-temperature toughness of the flange by adding rare earth for microalloying. The invention has the defects that the rare earth content is less, so that the solid solution rare earth in the steel is less, the rare earth element Ce only can not fully exert the purification effect of the rare earth grain boundary, and the rare earth composite inclusion obtained in the preparation can not inhibit the thermal deformation and the grain growth behavior in the heat treatment process.
Disclosure of Invention
In order to solve the problems, the steel for the fine-grain wind power flange and the manufacturing method thereof are provided, and on one hand, the grain size is refined through refining solidification structures of rare earth oxysulfide through microalloying, adding La rare earth elements and content proportion of other elements; on the other hand, alN is controlled to act along crystallization in the thermoforming and heat treatment processes, so that the whole-flow tissue refinement is realized, and meanwhile, the strength and the toughness of the flange are improved.
According to one aspect of the application, there is provided a steel for a fine-grain wind power flange, comprising, in weight percent: c:0.13-0.15%, si:0.17-0.40%, mn:1.2 to 1.6 percent, P is less than or equal to 0.025 percent, S is less than or equal to 0.003 percent, and Nb:0.03-0.05%, al <0.06%, ce less than or equal to 300ppm, la less than or equal to 300ppm, H less than or equal to 2ppm, O less than or equal to 20ppm, N less than or equal to 300ppm, and the balance of Fe and unavoidable impurities.
On one hand, the two elements can react with S, O in the steel to form rare earth sulfide and rare earth oxide, so that the content of S, O impurity elements in the steel can be reduced, the impurity elements are prevented from damaging a steel matrix structure, the rare earth sulfide and the rare earth oxide can serve as a basis for the growth of a steel structure, a steel structure can be quickly grown into a stable structure by taking the rare earth sulfide and the rare earth oxide as nucleation, and the content of the rare earth sulfide and the rare earth oxide is moderate and uniform in distribution, so that the particle uniformity and compactness of the grown steel structure can be improved, the microcosmic solidification structure of a steel ingot is refined, and the performances of various aspects of the steel are improved; on the other hand, ce and La are dispersed in steel in the form of pure elements, so that the content of rare earth elements in solid solution in the steel can be improved, the sizes of the two rare earth elements are larger than those of other elements, when the rare earth elements are mixed with other elements in the steel, impurity elements such as P, sn, sb and the like can be limited in a grain boundary, the diffusion of the elements to the outside of the grain boundary is effectively inhibited, the steel tissue structure is prevented from being damaged, the elements limited in the grain boundary can also play a supporting role on the grain boundary, the effect of strengthening the grain boundary is further achieved, and the low-temperature impact toughness of the flange can be remarkably improved.
Optionally, al multiplied by N is less than or equal to 1.2 multiplied by 10 in the steel for the fine-grain wind power flange -7 . Through the limitation of the product content of the Al and the N elements, the behavior of AlN along crystallization can be strictly controlled, so that the content of AlN precipitation is moderate, the aim of inhibiting the growth of austenite and ferrite is fulfilled, the whole-process tissue refinement is realized, and the Al can also be used as a deoxidizing element, thereby improving the cleanliness of a steel matrix.
Optionally, the content of Ce is greater than 80ppm and the content of La is greater than 20ppm.
Optionally, the weight ratio of Ce to La is (1.69-3.8): 1.
the Ce and La elements in the application can optimize the quantity and the precipitation form of the rare earth sulfide and the rare earth oxide, reduce the impurity content and simultaneously refine and homogenize the steel structure to the greatest extent; secondly, the solid solution quantity of the two elements can be improved, the rare earth grain boundary purification effect can be fully exerted, further grain boundary segregation of impurity elements such as P and the like is effectively inhibited, and the low-temperature toughness of the steel is remarkably improved; thirdly, the weight ratio of La and Ce can more effectively exert alloying effect, further improve the distribution uniformity of ferrite and pearlite and the gaps between the ferrite and pearlite, and improve the mechanical properties of the steel.
Optionally, the weight ratio of P to La is (1.2-3.35): 1. under the proportion, la element can play the best limiting role on P element, and can control the content of P element in the grain boundary, so that the P element can be uniformly dispersed in the grain boundary, meanwhile, the agglomeration of the P element in the grain boundary is avoided, the form uniformity of a steel structure can be improved on the basis of refining grains, and the moisture resistance and corrosion resistance of steel are further improved.
Optionally, the Ce and La are greater than 95% pure. The purity is set firstly to reduce the quantity of impurities introduced in the adding process of Ce and La, and avoid the influence of the impurities on the steel structure; secondly, the Ce and La can be ensured to fully exert the functions, and the refining effect on the crystal grains is further improved.
Optionally, the low-temperature impact energy of the steel for the fine-grain wind power flange at minus 60 ℃ is more than or equal to 177J, and the elongation at break is more than or equal to 35%.
Optionally, the tensile strength of the steel for the fine-grain wind power flange is 620-670MPa, and the yield strength is 420-480MPa.
Preferably, the tensile strength of the steel for the fine-grain wind power flange is 640-670MPa, and the yield strength is 440-480MPa.
According to another aspect of the present application, there is provided a method for manufacturing steel for a fine-grain wind power flange as set forth in any one of the above, comprising the steps of:
(1) Smelting:
melting scrap steel by adopting an electric arc furnace, adding pig iron, and tapping at a temperature of less than 1650 ℃ to obtain molten steel;
LF refining and VD vacuum treatment ensure the cleanliness of molten steel, the LF refining adopts a large slag quantity to carry out slag formation, the S content is ensured to be less than or equal to 0.003 percent, ferrocolumbium and Al are added in the refining process, and the Al content is controlled to be less than 0.06 percent;
the VD vacuum treatment time is longer than 25min, the N content is controlled to be less than or equal to 300ppm, ce and La elements are added when the vacuum treatment is carried out for 20min, and the adding amount of ton steel is less than or equal to 200 x ([ S% ] + [ O% ]) kg; the VD vacuum treatment ensures the deep vacuum circulation time of molten steel, and immediately puts a slag surface protective agent after the vacuum treatment to prevent the oxidation of the slag surface, and the argon soft blowing time is more than 20min;
(2) Casting:
the whole process of casting is protected during continuous casting, the superheat degree and the drawing speed are controlled, and the electromagnetic stirring technology is adopted to reduce the center segregation of the continuous casting blank;
argon protection is carried out at the ladle drain port during die casting, the superheat degree and the casting speed are controlled, and protective slag and a heating agent are timely added at a riser;
(3) Shaping by machining
The blank is cut off by sawing, so that the weight requirement of the flange is met; the flange is formed by adopting a free forging and ring rolling mode, the surface of a forging piece is cooled to be less than 950 ℃ after each fire forging, the forging piece can be heated in a furnace, the heat treatment adopts a normalizing and tempering process, and after the heat treatment, the forging piece is processed by adopting a lathe, so that the product is obtained.
Because Ce and La rare earth elements are added and react in molten steel or exist in a pure element form, the adding amount of ton steel in the step (1) is controlled by the contents of S element and O element, and the contents of rare earth sulfide and rare earth oxide can be controlled under the arrangement, so that the effect of refining and solidifying the structure of the rare earth oxysulfide is further improved.
Optionally, in the step (3), the normalizing temperature is 1100-1300 ℃ and the normalizing time T 1 =9th, where T 1 The unit of (1) is min, th is the effective thickness of the workpiece, the unit is mm, and the value range is 200-400;
tempering temperature is 700-750 ℃ and tempering time T 2 =120+th, where T 2 In min, th is the effective thickness of the workpiece, in mm, and takes on a valueRanging from 200 to 400.
The normalizing and tempering temperatures and times can enable the rare earth oxide and sulfide to quickly and effectively induce austenite nucleation to form uniform fine grain structure, ce and La atoms which are in solid solution in the cooling process quickly occupy crystal boundary vacancies, so that the crystal boundary segregation of elements such as P, S and the like can be inhibited, and pearlitic nuclei can be induced to further refine the structure. And because Ce and La two kinds of rare earth elements added in this application, once normalizing or tempering can satisfy wind-powered electricity generation flange and use the demand of steel, save processing procedure and reduce manufacturing cost, if increase the heat treatment number of times, can reduce the performance of this application steel on the contrary.
Optionally, the superheat degree in the continuous casting in the step (2) is controlled at 25-30 ℃, and the pulling speed is less than or equal to 0.90m/min;
and (2) controlling the superheat degree in die casting at 50-55 ℃ and the casting speed less than or equal to 2.5 tons/min.
During continuous casting, the superheat degree is controlled at 25-30 ℃, rare earth oxides and sulfides can be uniformly precipitated, dispersed in molten steel, the pulling speed is less than or equal to 0.90m/min, and the optimal AlN precipitation form and precipitation amount can be obtained; the superheat degree is controlled at 50-55 ℃ during die casting, so that rare earth oxide and sulfide can be further uniformly precipitated, the dispersion distribution uniformity of the rare earth oxide and sulfide in molten steel is improved, the pouring speed is less than or equal to 2.5 tons/min, the pouring speed can be cooperated with the pulling speed, the uniform precipitation of AlN is ensured, the uniformity degree of precipitation morphology is high, and the precipitation amount of AlN is further improved.
Benefits of the present application include, but are not limited to:
1. according to the steel for the fine-grained wind power flange, the inheritance and nucleation characteristics of the steel structure are utilized, the molten steel is induced to solidify through rare earth oxysulfide to form nuclei to refine the solidification structure, and then AlN in the steel is induced to separate out to inhibit the growth of austenite and ferrite, so that the fine crystallization of the flange steel matrix is finally realized.
2. According to the steel for the fine-grain wind power flange, through controlling the content of solid solution rare earth in the steel, grain boundary segregation of P and other impurity elements is effectively inhibited, the low-temperature toughness of the steel is remarkably improved, and finally the high-strength wind power flange with refined grains and high-low-temperature impact toughness is obtained.
3. According to the manufacturing method of the steel for the fine-grain wind power flange, which is disclosed by the application, the content of rare earth oxysulfide is controlled through the addition of ton steel and the technological conditions of continuous casting, die casting and heat treatment are controlled, so that the steel is subjected to full-flow tissue refinement, and the strength and toughness of the flange are further improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute an undue limitation to the application. In the drawings:
fig. 1 is a schematic diagram of the metallographic structure of test steel # 2 according to example 1 of the present application.
Detailed Description
The present application is described in detail below with reference to examples, but the present application is not limited to these examples.
Unless otherwise indicated, the starting materials in the examples of the present application were all purchased commercially
Example 1
Test steel No. 1-6 and comparative test steel No. D1-D4 were prepared according to the following process, the specific weight percentages of the components are shown in Table 1, and La element in test steel No. 2 was replaced with neodymium element to obtain comparative test steel No. D5.
(1) Smelting:
melting scrap steel by adopting an electric arc furnace, adding pig iron, and tapping at a temperature of less than 1650 ℃ to obtain molten steel;
LF refining and VD vacuum treatment ensure the cleanliness of molten steel, the LF refining adopts a large slag quantity to carry out slag formation, the S content is ensured to be less than or equal to 0.002 percent, ferrocolumbium and Al are added in the refining process, and the Al content is controlled to be less than 0.035 percent;
the VD vacuum treatment time is longer than 25min, the N content is controlled to be less than or equal to 300ppm, ce and La elements are added when the vacuum treatment is carried out for 20min, and the adding amount of ton steel is less than or equal to 200 x ([ S% ] + [ O% ]) kg; the VD vacuum treatment ensures the deep vacuum circulation time of molten steel, and immediately puts a slag surface protective agent after the vacuum treatment to prevent the oxidation of the slag surface, and the argon soft blowing time is more than 20min;
(2) Casting:
the whole process of casting is protected during continuous casting, the superheat degree is controlled to be 30 ℃, the pulling speed is controlled to be 0.90m/min, and the electromagnetic stirring technology is adopted to reduce the center segregation of a continuous casting billet;
argon protection is carried out at the ladle drain port during die casting, the superheat degree is controlled at 50 ℃, the casting speed is 2.5 tons/min, and casting powder and a heating agent are timely added at a riser;
(3) Shaping by machining
The blank is cut off by sawing, so that the weight requirement of the flange is met; the flange is formed by adopting a free forging and ring rolling mode, the surface of a forging piece is cooled to be less than 950 ℃ after each fire forging is finished, the forging piece can be heated in a furnace, the heat treatment adopts a normalizing and tempering process, the effective thickness of a workpiece is 300mm, the normalizing temperature is 1200 ℃, the normalizing time is 45h, the tempering temperature is 750 ℃, the tempering time is 7h, and the product is obtained after the heat treatment, the processing is carried out by adopting a lathe.
TABLE 1
Figure BDA0004120694380000071
The test steels obtained above were subjected to mechanical properties and grain size tests, wherein the grain size tests were carried out according to the metal average grain size measurement method of GB-T6394-2002, see in particular Table 2 below:
TABLE 2
Figure BDA0004120694380000081
According to the data in Table 2, the Ce and La elements added in the method can refine the grain size and the micro-solidification structure of the steel ingot, so that the performances of the flange in all aspects are improved, and the compactness and the morphological uniformity of the steel structure can be further improved under the specific proportion of the Ce and La elements and the P and La elements, so that the full synergistic action of all the components is ensured.
Example 2
Test steel # 714# was prepared by the manufacturing method of Table 3 below using the composition of test steel # 2, and the process conditions were the same as those of example 1 except for the process conditions listed in Table 3 below.
TABLE 3 Table 3
Figure BDA0004120694380000091
The test steels obtained above were subjected to mechanical properties testing, in particular as shown in table 4 below:
TABLE 4 Table 4
Figure BDA0004120694380000092
According to the data in Table 4, the manufacturing method of the present application is matched with the components of the flange, when the superheat degree of continuous casting and die casting is too low or too high, the uniformity of precipitation of rare earth oxide and sulfide is reduced, so that the mechanical property of the product is reduced, the pulling speed and the casting speed are too fast, the uniformity of AlN precipitation form and precipitation amount are reduced, the mechanical property of the product is also reduced, and especially the tensile strength is most obviously reduced; when the normalizing temperature and the annealing temperature are too low, the normalizing time or the tempering time is too short, the uniformity of fine grain structure is reduced, the refinement of crystal grains is not facilitated, and the performances of various aspects of products are further reduced.
The foregoing is merely exemplary of the present application, and the scope of the present application is not limited to the specific embodiments, but is defined by the claims of the present application. Various modifications and changes may be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the technical ideas and principles of the present application should be included in the protection scope of the present application.

Claims (10)

1. The steel for the fine-grain wind power flange is characterized by comprising the following components in percentage by weight: c:0.13-0.15%, si:0.17-0.40%, mn:1.2 to 1.6 percent, P is less than or equal to 0.025 percent, S is less than or equal to 0.003 percent, and Nb:0.03-0.05%, al <0.06%, ce less than or equal to 300ppm, la less than or equal to 300ppm, H less than or equal to 2ppm, O less than or equal to 20ppm, N less than or equal to 300ppm, and the balance of Fe and unavoidable impurities.
2. The steel for a fine-grain wind turbine flange according to claim 1, wherein al×n is 1.2×10 or less in the steel for a fine-grain wind turbine flange -7 。
3. The steel for a fine-grain wind power flange according to claim 1, characterized in that the Ce content is more than 80ppm and the La content is more than 20ppm.
4. The steel for a fine-grain wind power flange according to claim 1, characterized in that the weight ratio of Ce to La is (1.69-3.8): 1.
5. the steel for a fine-grain wind power flange according to claim 1, characterized in that the weight ratio of P to La is (1.2-3.35): 1.
6. the fine-grain wind power flange steel according to claim 1, characterized in that the purities of Ce and La are more than 95%.
7. The steel for fine-grain wind power flanges according to claim 1, characterized in that the low-temperature impact energy of-60 ℃ of the steel for fine-grain wind power flanges is not less than 177J and the elongation at break is not less than 35%.
8. The method for manufacturing a steel for a fine-grain wind power flange according to any one of claims 1 to 7, characterized by comprising the steps of:
(1) Smelting:
melting scrap steel by adopting an electric arc furnace, adding pig iron, and tapping at a temperature of less than 1650 ℃ to obtain molten steel;
LF refining and VD vacuum treatment ensure the cleanliness of molten steel, the LF refining adopts a large slag quantity to carry out slag formation, the S content is ensured to be less than or equal to 0.003 percent, ferrocolumbium and Al are added in the refining process, and the Al content is controlled to be less than 0.06 percent;
the VD vacuum treatment time is longer than 25min, the N content is controlled to be less than or equal to 300ppm, ce and La elements are added when the vacuum treatment is carried out for 20min, and the adding amount of ton steel is less than or equal to 200 x ([ S% ] + [ O% ]) kg; the VD vacuum treatment ensures the deep vacuum circulation time of molten steel, and immediately puts a slag surface protective agent after the vacuum treatment to prevent the oxidation of the slag surface, and the argon soft blowing time is more than 20min;
(2) Casting:
the whole process of casting is protected during continuous casting, the superheat degree and the drawing speed are controlled, and the electromagnetic stirring technology is adopted to reduce the center segregation of the continuous casting blank;
argon protection is carried out at the ladle drain port during die casting, the superheat degree and the casting speed are controlled, and protective slag and a heating agent are timely added at a riser;
(3) Shaping by machining
The blank is cut off by sawing, so that the weight requirement of the flange is met; the flange is formed by adopting a free forging and ring rolling mode, the surface of a forging piece is cooled to be less than 950 ℃ after each fire forging, the forging piece can be heated in a furnace, the heat treatment adopts a normalizing and tempering process, and after the heat treatment, the forging piece is processed by adopting a lathe, so that the product is obtained.
9. The method according to claim 8, wherein in the step (3), the normalizing temperature is 1100 to 1300 ℃ and the normalizing time T is set 1 =9th, where T 1 The unit of (1) is min, th is the effective thickness of the workpiece, the unit is mm, and the value range is 200-400;
tempering temperature is 700-750 ℃ and tempering time T 2 =120+th, where T 2 The unit of (2) is min, th is the effective thickness of the workpiece, the unit is mm, and the value range is 200-400.
10. The manufacturing method according to claim 8, wherein the degree of superheat in the continuous casting in the step (2) is controlled to 25-30 ℃, and the pulling speed is less than or equal to 0.90m/min;
and (2) controlling the superheat degree in die casting at 50-55 ℃ and the casting speed less than or equal to 2.5 tons/min.
CN202310231584.2A 2023-03-09 2023-03-09 Steel for fine-grain wind power flange and manufacturing method thereof Pending CN116083809A (en)

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