Steel for bearing outer ring of ultra-high power wind turbine generator set and its manufacturing process

Abstract

The present invention discloses a steel for the outer ring of a bearing of an extra-large power wind turbine generator and its manufacturing process, belonging to the technical field of wind power equipment manufacturing. A steel for the outer ring of a bearing of an extra-large power wind turbine generator comprises the following components by mass percentage: C 0.48% - 0.52%, Si 0.28% - 0.33%, Mn 0.62% - 0.66%, Cr 0.97% - 1.04%, Mo 0.16% - 0.21%, Ti 0.005 - 0.01%, Zr 0.003 - 0.008%, Ba 0.0007 - 0.001% and the balance of Fe. The present invention utilizes alloying elements such as Ti, Zr, Ba, etc. to refine the grain size and the inclusion size. At the same time, through extrusion and torsion, the microstructure of the billet and the degree of inclusion fragmentation and uniform distribution are enhanced, which is beneficial to obtaining fine and uniform metal flow lines after ring rolling, and improving the mechanical properties of the forging.

Description

Technical Field

[0001] The present invention relates to a steel for the outer ring of a bearing of an extra-large power wind turbine generator and a manufacturing process thereof, belonging to the technical field of wind power equipment manufacturing. Background Art

[0002] With the implementation of the national "dual carbon" policy, the wind power market has witnessed an explosive growth. As a core component of a wind turbine, during operation, the bearing needs to withstand huge loads and complex torque changes brought by the wind force, which poses high requirements for the strength and stability of the bearing. As the main component supporting the rolling elements, the quality and performance of the outer ring of the bearing directly affect the overall performance and service life of the bearing.

[0003] Currently, the outer ring of the bearing is mainly manufactured by free forging and rolling. However, for workpieces manufactured by free forging, the general diameter is ≤7500 mm, and the free forging process has many forging heats, a long cycle, poor homogenization of the internal structure of the forgings, and relatively high comprehensive production costs. Ring rolling is a popular forming process for manufacturing the outer ring of the bearing. Chinese Patent No. CN202110008625 discloses a manufacturing process for an extra-large wheel band forging, which uses a radial-axial rolling process to replace the traditional free forging process to manufacture an extra-large wheel band forging, with the characteristics of energy saving, high efficiency, high material utilization rate, etc., and the internal metal streamline is retained. To solve the problems of oval or warping deformation during ring rolling, Chinese Patent No. CN202010749403 discloses a process for rolling and shaping an extra-large integral ring forging. By optimizing the rolling process parameters, the ovality can be controlled within ≤15 mm. Chinese Patent No. CN202210019834.1 discloses a forging process for a 100CrMo7-3 steel wind power bearing race, and a wind power bearing race with excellent plastic toughness and low-temperature impact resistance is obtained through forging blanking, ring rolling and heat treatment. As wind turbine generators develop towards extra-large power (≥8 MW), the sizes of wind power gears and their outer rings tend to be large-sized. Due to the limited deformation force of ring rolling, it is impossible to fully break the internal structure of the outer ring of a large-sized (≥20 m) gear, resulting in uneven distribution of its internal structure and metal streamline, and the defects such as dendrites and inclusions in the core cannot be eliminated or reduced, which cannot meet the use requirements and service life requirements in a harsh service environment. Therefore, there is an urgent need to develop a new manufacturing method for the outer ring of a bearing for a wind turbine generator to solve the above problems. Summary of the Invention

[0004] The object of the present invention is to provide a steel for the outer ring of a bearing of an extra-large power wind turbine generator, which has fine grains (8 - 9 grades), uniform structure, and dense metal streamline, aiming at the problems existing in the prior art.

[0005] Meanwhile, the present invention provides a manufacturing process for the steel used in the bearing outer ring of an extra-large power wind turbine generator. By this method, a large-sized bearing outer ring for a wind turbine generator with fine grains (grade 8 - 9) and uniform structure can be obtained, and the metal streamline is dense.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] A steel for the bearing outer ring of an extra-large power wind turbine generator, with alloying components: C 0.48% - 0.52%, Si 0.28% - 0.33%, Mn 0.62% - 0.66%, Cr 0.97% - 1.04%, Mo 0.16% - 0.21%, Ti 0.005 - 0.01%, Zr 0.003 - 0.008%, Ba 0.0007 - 0.001%, and the balance being Fe.

[0008] The extra-large power is ≥8 MW.

[0009] The grains at the edge and the core of the steel obtained by the present invention are both grade 8 - 9, and the structure is uniform and the metal streamline is dense.

[0010] The tensile strength of the steel obtained by the present invention is 1057 - 1152 MPa, the elongation is 15.8 - 18.1%, the impact toughness at -40°C is 41 - 44 J / cm 2 , and the corrosion current density is 1.39 - 2.26 μA / cm 2 .

[0011] A manufacturing process for the bearing outer ring of an extra-large power wind turbine generator, comprising the following steps:

[0012] 1) Blank heating: Heat the blank to 1200°C - 1250°C and hold for 1.5 - 2 h;

[0013] 2) Strong magnetic field-assisted torsion blank making: First, place the blank in a mold for rough forging, with a forging ratio of 2.1 - 2.4; then apply a strong magnetic field to the rough-forged blank and perform torsional deformation treatment, with a magnetic field strength of 12 - 15 T, a working temperature of 900 - 1050°C, a torsional speed of 3 - 6° / s, and a torsional time of 60 - 90 s.

[0014] 3) Multi-field coupling-assisted ring rolling forming of magnetic + electric + ultrasonic:

[0015] The temperature for the first ring rolling is 1200 - 1250°C, the linear speed of the main roll is 900 - 1000 mm / s, the radial feed speed of the core roll is 0.5 - 0.6 mm / s, the rotational speed of the taper roll is 8.0 - 9.0 rad / s, the ultrasonic frequency is 20 - 25 kHz, the ultrasonic amplitude is 12 - 15 μm, the pulse current frequency is 800 - 1000 Hz, and the peak current density is 12 - 15 A / mm2 The total time of a single pulse is 1500 - 2000 μs, the pulse interval is 1800 - 2000 ms, and the magnetic field strength is 9 - 12 T.

[0016] The temperature for secondary ring rolling is 1000 - 1050 °C, the linear speed of the main roller is 850 - 950 mm / s, the radial feed speed of the core roller is 0.3 - 0.4 mm / s, the rotational speed of the conical roller is 8.0 - 8.5 rad / s, the ultrasonic frequency is 10 - 15 kHz, and the ultrasonic amplitude is 8 - 10 μm; the pulse current frequency is 500 - 700 Hz, and the peak current density is 8 - 10 A / mm 2 The total time of a single pulse is 800 - 1000 μs, and the pulse interval is 400 - 500 ms.

[0017] Application of steel for the outer ring of bearings of ultra - large - power wind turbine generators in the outer ring of bearings of large - scale wind turbine generators.

[0018] Large - scale includes an inner diameter ≥ 20 m.

[0019] Application of steel for the outer ring of bearings of ultra - large - power wind turbine generators in ultra - large - power wind turbine generators.

[0020] The outer ring of bearings of large - scale wind turbine generators is prepared by using the steel for the outer ring of bearings of ultra - large - power wind turbine generators of the present invention.

[0021] Alloying effects: C is a strengthening element; Si is a deoxidizing and strengthening element; Mn is a deoxidizing element and an element to improve the hardenability of steel, and it also plays a role in solid - solution strengthening and fixing sulfides in steel; Cr is a carbide - forming element and can improve the tempering stability; Mo is a grain - refining element, which can improve the hardenability and thermal strength of steel, prevent temper brittleness, and increase the remanent magnetism and coercivity; Ti is a deoxidizing and grain - refining element; Zr is a grain - refining, deoxidizing, nitrogen - removing, and sulfur - removing element, and it can inhibit the growth of austenite grains at high temperatures; Ba is an element to refine inclusions and optimize their distribution.

[0022] Basic principle of strong - magnetic - field - assisted torsion for blank preparation: By using a strong magnetic field and torsion, the material can be fully broken in the billet structure under the action of extrusion and shear deformation, which can not only refine grains but also break and disperse inclusions in the billet; in addition, under the action of a strong magnetic field, the process of grain recrystallization can be slowed down, and grains can be refined.

[0023] Basic principle of multi - field coupling of magnetic + electric + ultrasonic - assisted ring rolling forming: By using ultrasonic vibration, the yield strength and flow stress of the material can be reduced. At the same time, by using the thermal effect and non - thermal effect of pulsed current, the metal flow ability can be improved, the deformation depth in the radial and axial directions can be enhanced, which is beneficial to the deformation of the billet core structure. At the same time, by using the action of a strong magnetic field, the grain recrystallization can be slowed down, and grains can be refined.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: alloying elements such as Ti, Zr, and Ba are used to refine the grain size and the inclusion size. At the same time, extrusion and torsion are used to enhance the structure of the billet and the degree of inclusion fragmentation and uniform distribution, which is beneficial to obtaining fine and uniform metal flow lines after ring rolling. Electric pulse and ultrasonic are used to improve the fluidity of the metal, enhance the deformation depth during ring rolling, solve the problem of insufficient deformation of the traditional core structure, and significantly optimize the rolling quality; the Zr element and the strong magnetic field are used to slow down the grain growth at high temperatures, maintain fine grains, and improve the mechanical properties of the forging. Brief Description of the Drawings

[0025] Figure 1 The strong magnetic field assisted torsion device of the present invention: 1 - upper punch, 2 - electromagnetic coil, 3 - mandrel, 4 - billet, 5 - lower die head;

[0026] Figure 2 Metal flow lines at different parts of the present invention and the comparative bearing outer ring: (a) outer side edge of the sample of Example 1 of the present invention, (b) core of the sample of Example 1 of the present invention, (c) inner side edge of the sample of Example 1 of the present invention, (d) outer side edge of the sample of Comparative Example 5, (e) core of the sample of Comparative Example 5, (f) inner side edge of the sample of Comparative Example 5;

[0027] Figure 3 Grain sizes at different parts of the present invention and the comparative bearing outer ring: (a) edge of the sample of Example 1 of the present invention, (b) core of the sample of Example 1 of the present invention, (c) edge of the sample of Comparative Example 5, (d) core of the sample of Comparative Example 5. Detailed Description of the Invention

[0028] The present invention will be further described in detail below with reference to the drawings and specific embodiments. The following embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0029] Example 1

[0030] A steel for the outer ring of a super-large power wind turbine generator bearing includes the following chemical components: C 0.48%, Si 0.28%, Mn 0.62%, Cr 0.97%, Mo 0.16%, Ti 0.005%, Zr 0.003%, Ba 0.0007% and the balance Fe.

[0031] A manufacturing process of a steel for the outer ring of a super-large power wind turbine generator bearing includes the following steps:

[0032] 1) Billet heating: Heat the billet to 1200 °C and hold for 1.5 h;

[0033] 2) Strong magnetic field assisted torsion blanking: First, place the billet in the mold for rough forging, as Figure 1As shown, the forging ratio is 2.1; subsequently, a strong magnetic field is applied to the billet after rough forging, and torsional deformation treatment is carried out. The magnetic field strength is 12 T, the working temperature is 900 °C, the torsional speed is 3° / s, and the torsional time is 60 s.

[0034] 3) Magnetic + electric + ultrasonic multi-field coupling assisted ring rolling forming: The temperature for the first ring rolling is 1200 °C, the linear speed of the main roll is 900 mm / s, the radial feed speed of the core roll is 0.5 mm / s, the rotational speed of the taper roll is 8.0 rad / s, the ultrasonic frequency is 20 kHz, the ultrasonic amplitude is 12 μm, the pulse current frequency is 800 Hz, and the peak current density is 12 A / mm 2 , the total time of a single pulse is 2000 μs, the pulse interval is 2000 ms, and the magnetic field strength is 9 T; the temperature for the second ring rolling is 1000 °C, the linear speed of the main roll is 850 mm / s, the radial feed speed of the core roll is 0.3 mm / s, the rotational speed of the taper roll is 8.0 rad / s, the ultrasonic frequency is 10 kHz, and the ultrasonic amplitude is 8 μm; the pulse current frequency is 500 Hz, and the peak current density is 8 A / mm 2 , the total time of a single pulse is 1000 μs, and the pulse interval is 500 ms.

[0035] The application of a steel for the outer ring of a super-large power wind turbine generator bearing in the outer ring of a large-scale wind turbine generator bearing.

[0036] The large scale has an inner diameter of 20 m.

[0037] The application of a steel for the outer ring of a super-large power wind turbine generator bearing in a super-large power wind turbine generator.

[0038] The super-large power is 8 MW

[0039] The outer ring of a large-scale wind turbine generator bearing is prepared by using a steel for the outer ring of a super-large power wind turbine generator bearing in this embodiment.

[0040] Figure 1 Among them, the mold is composed of a matching upper punch 1 and a lower die head 5. The lower surface of the upper punch 1 is integrally connected with a mandrel 3 extending downward. The upper surface of the lower die head 5 is provided with a groove for placing a billet 4. A hole is provided in the center of the billet 4. The mandrel 3 is located in the central hole of the billet 4. Electromagnetic coils 2 for providing a strong magnetic field are provided on both the upper punch 1 and the lower die head 5; the billet 4 is placed in the mold for rough forging, and then a strong magnetic field is applied to the billet after rough forging, and torsional deformation treatment is carried out. The torsional deformation treatment is to twist the lower die head 5.

[0041] As Figure 2As shown, the steel for the outer ring of the super-large power wind turbine generator bearing obtained in this embodiment has little difference in the metal flow lines in each area (outer side, core, and inner side), and they are all fine. However, for the sample of Comparative Example 5, because the deep deformation of the core is insufficient, the flow lines in the core area are coarser than those in the edge area.

[0042] As Figure 3 shown, the grain diagrams of the edge and core of the steel for the outer ring of the super-large power wind turbine generator bearing obtained in this embodiment are presented. The grain grades in this embodiment are all Grade 8, and the microstructure is uniform. For the sample of Comparative Example 5, due to the absence of an external field, the grain size of the edge is slightly larger. At the same time, the deformation force in the core area is insufficient and the stress is uneven, resulting in coarse and uneven grains in the core area, and serious local grain coarsening.

[0043] Example 2

[0044] A steel for the outer ring of a super-large power wind turbine generator bearing includes the following chemical components: C 0.49%, Si 0.30%, Mn 0.64%, Cr 0.99%, Mo 0.18%, Ti 0.007%, Zr 0.006%, Ba 0.0008%, and the balance is Fe.

[0045] The manufacturing process includes the following steps:

[0046] 1) Blank heating: Heat the blank to 1250 °C and hold for 2 h;

[0047] 2) Strong magnetic field-assisted torsion billet making: First, place the blank in a mold for rough forging, as Figure 1 shown, the forging ratio is 2.3; subsequently, apply a strong magnetic field to the rough-forged blank and perform torsion deformation treatment. The magnetic field strength is 14 T, the working temperature is 1050 °C, the torsion speed is 4° / s, and the torsion time is 90 s.

[0048] 3) Multi-field coupling-assisted ring rolling forming of magnetic + electric + ultrasonic: The temperature for the first ring rolling is 1250 °C, the linear speed of the main roll is 950 mm / s, the radial feed speed of the core roll is 0.55 mm / s, the rotational speed of the taper roll is 8.5 rad / s, the ultrasonic frequency is 22 kHz, the ultrasonic amplitude is 13 μm, the pulse current frequency is 900 Hz, the peak current density is 13 A / mm 2 , the total time of a single pulse is 1500 μs, the pulse interval is 1800 ms, and the magnetic field strength is 10 T; the temperature for the second ring rolling is 1050 °C, the linear speed of the main roll is 950 mm / s, the radial feed speed of the core roll is 0.35 mm / s, the rotational speed of the taper roll is 8.3 rad / s, the ultrasonic frequency is 13 kHz, the ultrasonic amplitude is 9 μm; the pulse current frequency is 550 Hz, the peak current density is 9 A / mm 2 , the total time of a single pulse is 800 μs, and the pulse interval is 400 ms.

[0049] Application of steel for outer ring of bearing of super-large power wind turbine generator in outer ring of bearing of large-scale wind turbine generator

[0050] The large scale has an inner diameter of 25 m.

[0051] Application of steel for outer ring of bearing of super-large power wind turbine generator in super-large power wind turbine generator

[0052] The super-large power is 10 MW.

[0053] The outer ring of the bearing of the large-scale wind turbine generator is prepared by using the steel for the outer ring of the bearing of the super-large power wind turbine generator of this embodiment.

[0054] Example 3

[0055] A steel for the outer ring of a bearing of a super-large power wind turbine generator, comprising the following chemical components: C 0.51%, Si 0.31%, Mn 0.65%, Cr 1.0%, Mo 0.21%, Ti 0.01%, Zr 0.007%, Ba 0.0008% and the balance Fe.

[0056] The manufacturing process comprises the following steps:

[0057] 1) Blank heating: The blank is heated to 1220 °C and held for 1.8 h;

[0058] 2) Strong magnetic field assisted torsion blank making: First, the blank is placed in a mold for rough forging, as Figure 1 shown, the forging ratio is 2.4; then a strong magnetic field is applied to the rough forged blank, and torsion deformation treatment is carried out, the magnetic field strength is 15 T, the working temperature is 1000 °C, the torsion speed is 5° / s, and the torsion time is 70 s.

[0059] 3) Magnetic + electric + ultrasonic multi-field coupling assisted ring rolling forming: The temperature of the first ring rolling is 1225 °C, the linear speed of the main roll is 970 mm / s, the radial feed speed of the core roll is 0.6 mm / s, the rotational speed of the taper roll is 9.0 rad / s, the ultrasonic frequency is 25 kHz, the ultrasonic amplitude is 15 μm, the pulse current frequency is 900 Hz, the peak current density is 14 A / mm 2 , the total time of a single pulse is 2000 μs, the pulse interval is 2000 ms, and the magnetic field strength is 11 T; the temperature of the second ring rolling is 1020 °C, the linear speed of the main roll is 875 mm / s, the radial feed speed of the core roll is 0.4 mm / s, the rotational speed of the taper roll is 8.5 rad / s, the ultrasonic frequency is 12 kHz, the ultrasonic amplitude is 9 μm; the pulse current frequency is 700 Hz, the peak current density is 9 A / mm 2 , the total time of a single pulse is 1000 μs, and the pulse interval is 500 ms.

[0060] Application of steel for outer ring of bearing of extra-large power wind turbine generator in outer ring of bearing of large-scale wind turbine generator.

[0061] The large scale has an inner diameter of 23 m.

[0062] Application of steel for outer ring of bearing of extra-large power wind turbine generator in extra-large power wind turbine generator.

[0063] The extra-large power is 10 MW.

[0064] The outer ring of bearing of large-scale wind turbine generator is prepared by using the steel for outer ring of bearing of extra-large power wind turbine generator of this embodiment.

[0065] Example 4

[0066] A steel for outer ring of bearing of extra-large power wind turbine generator, comprising the following chemical components: C 0.52%, Si 0.33%, Mn 0.66%, Cr 1.04%, Mo 0.21%, Ti 0.01%, Zr 0.008%, Ba 0.001% and the balance Fe.

[0067] The manufacturing process comprises the following steps:

[0068] 1) Blank heating: The blank is heated to 1235 °C and held for 1.9 h;

[0069] 2) Strong magnetic field assisted torsion billet making: First, the blank is placed in a die for rough forging, as Figure 1 shown, with a forging ratio of 2.4; Subsequently, a strong magnetic field is applied to the rough forged blank, and torsion deformation treatment is carried out, with a magnetic field strength of 15 T, a working temperature of 1050 °C, a torsion speed of 6° / s, and a torsion time of 80 s.

[0070] 3) Magnetic + electric + ultrasonic multi-field coupling assisted ring rolling forming: The temperature of the first ring rolling is 1250 °C, the linear speed of the main roll is 1000 mm / s, the radial feed speed of the core roll is 0.6 mm / s, the rotational speed of the conical roll is 9.0 rad / s, the ultrasonic frequency is 20 - 25 kHz, the ultrasonic amplitude is 15 μm, the pulse current frequency is 1000 Hz, the peak current density is 15 A / mm 2 , the total time of a single pulse is 2000 μs, the pulse interval is 2000 ms, and the magnetic field strength is 12 T; The temperature of the second ring rolling is 1050 °C, the linear speed of the main roll is 950 mm / s, the radial feed speed of the core roll is 0.4 mm / s, the rotational speed of the conical roll is 8.5 rad / s, the ultrasonic frequency is 15 kHz, and the ultrasonic amplitude is 10 μm; The pulse current frequency is 700 Hz, the peak current density is 10 A / mm 2 , the total time of a single pulse is 1000 μs, and the pulse interval is 500 ms.

[0071] Application of steel for outer ring of bearing of extra-large power wind turbine generator in outer ring of bearing of large-scale wind turbine generator.

[0072] The large scale has an inner diameter of 28 m.

[0073] Application of steel for outer ring of bearing of extra-large power wind turbine generator in extra-large power wind turbine generator.

[0074] The extra-large power is 12 MW.

[0075] The outer ring of the bearing of the large-scale wind turbine generator is prepared by using the steel for the outer ring of the bearing of the extra-large power wind turbine generator of this embodiment.

[0076] Comparative Example 1

[0077] The difference between this comparative example and Example 1 is only that: there is no Zr in the alloy composition.

[0078] Comparative Example 2

[0079] The difference between this comparative example and Example 1 is only that: there is no Ba in the alloy composition.

[0080] Comparative Example 3

[0081] The difference between this comparative example and Example 1 is only that: in step 2), super-strong magnetic field assisted torsion is adopted, a super-strong magnetic field is applied to the billet after rough forging, and torsion deformation treatment is carried out, and the magnetic field strength is: 20 T.

[0082] Comparative Example 4

[0083] The difference between this comparative example and Example 1 is only that: in step 3), only ultrasonic assisted ring rolling is adopted, and the specific process is: the temperature of the first ring rolling is 1250 °C, the linear speed of the main roll is 950 mm / s, the radial feed speed of the core roll is 0.55 mm / s, the rotational speed of the cone roll is 8.5 rad / s, the ultrasonic frequency is 22 kHz, the ultrasonic amplitude is 13 μm, and the ultrasonic time is 4000 μs; the temperature of the second ring rolling is 1050 °C, the linear speed of the main roll is 950 mm / s, the radial feed speed of the core roll is 0.35 mm / s, the rotational speed of the cone roll is 8.3 rad / s, the ultrasonic frequency is 13 kHz, the ultrasonic amplitude is 9 μm, and the ultrasonic time is 2000 μs.

[0084] Comparative Example 5

[0085] The difference between this comparative example and Example 1 is only that: in step 3), only electric + ultrasonic multi-field coupling assisted ring rolling forming is adopted;

[0086] The specific process is as follows: for the first ring rolling, the temperature is 1200 °C, the linear speed of the main roll is 900 mm / s, the radial feed speed of the core roll is 0.5 mm / s, the rotational speed of the conical roll is 8.0 rad / s, the ultrasonic frequency is 20 kHz, the ultrasonic amplitude is 12 μm, the pulse current frequency is 800 Hz, and the peak current density is 12 A / mm 2 , the total time of a single pulse is 2000 μs, and the pulse interval is 2000 ms; for the second ring rolling, the temperature is 1000 °C, the linear speed of the main roll is 850 mm / s, the radial feed speed of the core roll is 0.3 mm / s, the rotational speed of the conical roll is 8.0 rad / s, the ultrasonic frequency is 10 kHz, and the ultrasonic amplitude is 8 μm; the pulse current frequency is 500 Hz, and the peak current density is 8 A / mm 2 , the total time of a single pulse is 1000 μs, and the pulse interval is 500 ms.

[0087] As Figure 2 shown, for the steel used for the outer ring of the wind turbine generator bearing obtained in this comparative example, the metal flow lines in each area (outer side, core, and inner side) vary greatly. Because the depth of deformation in the core is insufficient, the flow lines in the core area are coarser than those in the edge area.

[0088] As Figure 3 shown, for the grain diagram of the side and core of the steel used for the outer ring of the wind turbine generator bearing obtained in this comparative example, the grain grade of this comparative example: the side is grade 8, and the core is grade 7, and the structure is uneven. Since no external field is applied to the sample of this comparative example, the grain size of the side is slightly larger. At the same time, the deformation force in the core area is insufficient and the force is uneven, resulting in coarse and uneven grains in the core area, and serious local grain coarsening.

[0089] Comparative Example 6

[0090] The difference between this comparative example and Example 1 is only that: in step 3), only magnetic + ultrasonic multi-field coupling assisted ring rolling forming is adopted;

[0091] The specific process is as follows: for the first ring rolling, the temperature is 1200 °C, the linear speed of the main roll is 900 mm / s, the radial feed speed of the core roll is 0.5 mm / s, the rotational speed of the conical roll is 8.0 rad / s, the ultrasonic frequency is 20 kHz, the ultrasonic amplitude is 12 μm, the ultrasonic time is 4000 μs, and the magnetic field strength is 9 T; for the second ring rolling, the temperature is 1000 °C, the linear speed of the main roll is 850 mm / s, the radial feed speed of the core roll is 0.3 mm / s, the rotational speed of the conical roll is 8.0 rad / s, the ultrasonic frequency is 10 kHz, and the ultrasonic amplitude is 8 μm; the ultrasonic time is 2000 μs.

[0092] Comparative Example 7

[0093] The difference between this comparative example and Example 1 is only that: in step 3), only magnetic + electric assisted ring rolling forming is adopted;

[0094] The specific process is as follows: the temperature for the first ring rolling is 1200 °C, the linear speed of the main roller is 900 mm / s, the radial feeding speed of the core roller is 0.5 mm / s, the rotational speed of the conical roller is 8.0 rad / s, the pulse current frequency is 800 Hz, and the peak current density is 12 A / mm 2 ; the total time of a single pulse is 2000 μs, the pulse interval is 2000 ms, and the magnetic field strength is 9 T; the temperature for the second ring rolling is 1000 °C, the linear speed of the main roller is 850 mm / s, the radial feeding speed of the core roller is 0.3 mm / s, the rotational speed of the conical roller is 8.0 rad / s, the pulse current frequency is 500 Hz, and the peak current density is 8 A / mm 2 , the total time of a single pulse is 1000 μs, and the pulse interval is 500 ms.

[0095] Comparative Example 8

[0096] The difference between this comparative example and Example 1 is only that: during the second ring rolling in step 3), a magnetic field is also used, and the magnetic field strength is 7 T.

[0097] Comparative Example 9

[0098] The steel for the outer ring of the bearing of a wind turbine generator set includes the following chemical components: C 0.45%, Si 0.37%, Mn 0.68%, Cr 1.05%, Mo 0.19%, Ni 0.13%, Cu 0.18%.

[0099] The manufacturing process includes the following steps:

[0100] 1) Blank heating: Heat the blank to 1200 °C and keep it warm for 2 h;

[0101] 2) Forging and blank making: Upset the blank successively according to the forging ratios of 1.78, 2.1, and 2.3, and then punch holes.

[0102] 3) Ring rolling forming: The temperature for the first ring rolling is 1200 °C, the linear speed of the main roller is 900 mm / s, the radial feeding speed of the core roller is 0.6 mm / s, the rotational speed of the conical roller is 9.0 rad / s, the temperature for the second ring rolling is 1000 °C, the linear speed of the main roller is 950 mm / s, the radial feeding speed of the core roller is 0.25 mm / s, and the rotational speed of the conical roller is 7.0 rad / s.

[0103] For the steel for the outer ring of the bearing of a wind turbine generator set obtained in Examples 1 to 4 and Comparative Examples 1 to 9, the metallurgical quality is shown in Table 1 below, and the mechanical properties are shown in Table 2 below.

[0104] Table 1 Metallurgical Quality of Examples and Comparative Samples

[0105]

[0106]

[0107] Table 2 Mechanical Properties of Examples and Comparative Samples

[0108]

[0109] The grain grading refers to GB / T 6394-2002, the detection of non-metallic inclusions refers to GB / T 10561-2005, the detection of tensile strength and elongation refers to GB / T 228.1-2021, the detection of impact toughness refers to GB / T 229-2020, and the test of corrosion current density refers to GB / T 24196-2009.

[0110] It should be understood that, in order to streamline the present disclosure and assist in understanding one or more of the various inventive aspects, in the above description of the exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, the disclosed method should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected by the claims, the inventive aspects lie in less than all of the features of the previously disclosed embodiments. Thus, the claims following the detailed description are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate embodiment of the present invention.

[0111] Although the present invention has been described in terms of a limited number of embodiments, those skilled in the art within this technical field will appreciate, based on the above description, that other embodiments can be contemplated within the scope of the invention thus described. In addition, it should be noted that the language used in this specification has been principally selected for readability and instructional purposes, rather than for the purpose of explaining or limiting the subject matter of the present invention. Accordingly, many modifications and variations will be apparent to those of ordinary skill in this technical field without departing from the scope and spirit of the appended claims. For the scope of the present invention, the disclosure of the present invention is illustrative, not restrictive, and the scope of the present invention is defined by the appended claims.

[0112] The above are only the preferred embodiments of the present invention, and it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A steel for outer ring of bearing of super high power wind turbine generator set, characterized in that: The invention comprises the following components in mass percentage: C 0.48% to 0.52%, Si 0.28% to 0.33%, Mn 0.62% to 0.66%, Cr 0.97% to 1.04%, Mo 0.16% to 0.21%, Ti 0.005 to 0.01%, Zr 0.003 to 0.008%, Ba 0.0007 to 0.001% and the balance Fe; Ultra-high power is ≥8MW; The grains at the edge and center of the steel are both level 8~9, with uniform structure and dense metal streamlines.

2. The steel for outer ring of bearing of super high power wind turbine generator set according to claim 1, characterized in that: The tensile strength of the steel is 1057~1152 MPa, the elongation is 15.8~18.1%, and the impact toughness at -40℃ is 41~44 J / cm 2 , the corrosion current density is 1.39~2.26μA / cm 2 .

3. A manufacturing process for the steel for the outer ring of the bearing of a super-high-power wind turbine generator set according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1, billet heating: heat the billet to 1200℃~1250℃, keep warm for 1.5~2h; S2, strong magnetic field assisted torsion blanking: firstly, the heated blank is placed in a die for rough forging, with a forging ratio of 2.1-2.4; then, a strong magnetic field is applied to the blank after rough forging, and a torsion deformation treatment is performed, with a magnetic field intensity of 12-15T, a working temperature of 900-1050℃, a torsion speed of 3-6° / s, and a torsion time of 60-90s; S3, magnetic + electric + ultrasonic multi-field coupling assisted ring rolling: The primary ring rolling temperature is 1200~1250℃, the main roller linear speed is 900~1000mm / s, the core roller radial feed speed is 0.5~0.6mm / s, the cone roller rotation speed is 8.0~9.0rad / s, the ultrasonic frequency is 20~25kHz, the ultrasonic amplitude is 12~15μm, the pulse current frequency is 800~1000Hz, and the peak current density is 12~15A / mm 2 , the total time of a single pulse is 1500~2000μs, the pulse interval is 1800~2000ms, and the magnetic field intensity is 9~12T; The secondary ring rolling temperature is 1000~1050℃, the main roller linear speed is 850~950mm / s, the core roller radial feed speed is 0.3~0.4mm / s, the cone roller rotation speed is 8.0~8.5rad / s, the ultrasonic frequency is 10~15kHz, the ultrasonic amplitude is 8~10 μm; the pulse current frequency is 500~700Hz, and the peak current density is 8~10A / mm 2 The total time of a single pulse is 800~1000μs, and the pulse interval is 400~500ms.

4. Application of the steel for outer ring of a bearing of a super-high-power wind turbine generator set according to any one of claims 1 to 2 in the outer ring of a bearing of a large-scale wind turbine generator set, characterized in that: Large specifications include inner diameter ≥20m.

5. Application of the steel for outer ring of bearing of super-high power wind generator set according to any one of claims 1 to 2 in super-high power wind generator set.

6. Large-sized wind turbine bearing outer ring, characterized in that: The outer ring of the bearing of a super-high-power wind turbine generator set is prepared by using the steel for the outer ring of the bearing of a super-high-power wind turbine generator set as described in any one of claims 1 to 2.

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