A high-strength and toughness wind power bearing steel and its preparation method, use and a wind power bearing

Abstract

The present invention belongs to the field of alloy steel and metallurgical technology, and specifically relates to a high-strength and toughness wind power bearing steel, a preparation method, a use, and a wind power bearing. The wind power bearing steel contains 1.88% to 3.96% Cu and 1.13% to 2.15% Ti. The preparation of the wind power bearing steel adopts molten steel smelting, LF refining, VD refining, three-stage gradient rolling and four-level performance heat treatment, so that there are Cu-rich primary precipitation phase and CuTi secondary precipitation phase in its microstructure matrix, and the phase interface between the Cu-rich primary precipitation phase and the matrix is ​​a completely coherent interface. The wind power bearing steel has the advantages of high yield strength, tensile strength, impact toughness, and elongation after fracture, has high strength and toughness, and is suitable for the harsh working conditions of wind power bearings.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy steel and metallurgy, and specifically relates to a high-strength and toughness wind power bearing steel, a preparation method, a use thereof and a wind power bearing. Background Art

[0002] In recent years, as the whole society attaches great importance to the development of renewable energy, the wind power industry has risen rapidly and become an important part of the energy system. The large-scale development and utilization of wind power has not only effectively alleviated the tight energy supply situation, but also promoted the optimization and upgrading of the energy structure.

[0003] Wind power bearing steel, as the core material in wind power equipment, has a performance that is directly related to the safe operation and long-term stability of the entire wind power equipment. Faced with harsh natural conditions, such as extreme wind speed changes, strong temperature fluctuations, high-salinity marine environment, and continuous mechanical stress, wind power bearing steel must have high-strength and tough mechanical properties to ensure long-term stable operation of wind turbines under high speed and heavy load.

[0004] In the process of wind power generation, high-speed rotation and high torque transmission are a major challenge faced by wind power bearings. The huge torque and axial force generated by the rotation of the blades are transmitted to the bearings through the main shaft, and the bearings rely on their internal steel raceways and rolling elements to withstand these loads. This requires that wind power bearing steel must have extremely high tensile strength and yield strength to ensure that no fracture or plastic deformation occurs under extreme working conditions. High-strength wind power bearing steel can effectively resist heavy loads and impacts, ensuring the stable operation of wind power equipment under severe weather conditions. On the other hand, in the actual operation of wind power equipment, due to the unpredictability and sudden changes in wind speed, the bearings may suffer from instantaneous overloads or impacts, which puts higher requirements on the toughness of wind power bearing steel, otherwise brittle fractures may occur in these sudden situations, resulting in failure or even damage to the entire wind power equipment. In this context, with the continuous improvement of wind power megawatt levels, the requirements for the strength and toughness of wind power gears and bearings are also increasing.

[0005] Therefore, those skilled in the art are in urgent need of developing a high-strength and high-toughness wind power bearing steel to solve the above problems. Summary of the invention

[0006] In view of the above problems, the present invention aims to provide a high-strength and toughness wind power bearing steel, a preparation method, a use and a wind power bearing.

[0007] The technical solution of the present invention is as follows:

[0008] In a first aspect, the present invention provides a high-strength and toughness wind power bearing steel, wherein the element composition of the high-strength and toughness wind power bearing steel is as follows by mass percentage: C: 0.13%~0.19%, Si: 0.36%~0.45%, Mn: 0.43%~0.87%, Cu: 1.88%~3.96%, Cr: 1.30%~1.90%, Ni: 1.70%~2.43%, Mo: 0.24%~0.33%, V: 0.08%~0.17%, Ti: 1.13%~2.15 %, N: 0.003%~0.007%, Al: ≤0.015%, P: ≤0.005%, S: ≤0.005%, and the balance is Fe and unavoidable impurities; there are Cu-rich primary precipitation phase and CuTi secondary precipitation phase in the microstructure matrix of the high-strength and toughness wind power bearing steel, the phase interface between the Cu-rich primary precipitation phase and the matrix is ​​a completely coherent interface, the Cu atomic ratio content of the Cu-rich primary precipitation phase is ≥80%; the CuTi atomic ratio content of the CuTi secondary precipitation phase is ≥95%.

[0009] Preferably, the Cu atomic ratio content of the Cu-rich primary precipitation phase of the high-strength and toughness wind power bearing steel is 80.1%~80.4%, and the CuTi atomic ratio content of the CuTi secondary precipitation phase of the high-strength and toughness wind power bearing steel is 97.6%~98.2%.

[0010] Preferably, the element composition of the high-strength and toughness wind power bearing is calculated by mass percentage as follows: C: 0.19%; Si: 0.36%; Mn: 0.87%; Cu: 3.96%; Cr: 1.90%; Ni: 2.430%; Mo: 0.33%; V: 0.17%; Ti: 1.13%; N: 0.007%; Al: ≤0.015%; P: ≤0.005%; S: ≤0.005%; the remainder is Fe and unavoidable impurities.

[0011] Preferably, the element composition of the high-strength and toughness wind power bearing is calculated by mass percentage as follows: C: 0.13%; Si: 0.45%; Mn: 0.43%; Cu: 1.88%; Cr: 1.30%; Ni: 1.70%; Mo: 0.24%; V: 0.08%; Ti: 2.15%; N: 0.003%; Al: ≤0.015%; P: ≤0.005%; S: ≤0.005%; the remainder is Fe and unavoidable impurities.

[0012] Preferably, the element composition of the high-strength and toughness wind power bearing is calculated by mass percentage as follows: C: 0.15%; Si: 0.41%; Mn: 0.66%; Cu: 2.53%; Cr: 1.6%; Ni: 2.01%; Mo: 0.28%; V: 0.11%; Ti: 1.95%; N: 0.005%; Al: ≤0.015%; P: ≤0.005%; S: ≤0.005%; the remainder is Fe and unavoidable impurities.

[0013] In a second aspect, the present invention provides a method for preparing the aforementioned high-strength and toughness wind power bearing steel, comprising the following steps:

[0014] S1 Molten Steel Smelting: The smelting furnace is heated to smelt the raw materials into molten iron. After the C content of the molten iron reaches the standard, oxygen is blown and quicklime is added to slag and steel is tapped to obtain molten steel;

[0015] S2 refining outside the furnace: including LF refining and VD refining:

[0016] S21 LF refining: the smelted steel is transferred to the LF refining furnace, the temperature is raised, titanium iron, copper iron, chromium iron master alloy are added, argon is blown in for stirring, aluminum wire is fed for deoxidation and slag formation, and refined steel is obtained. The refining time is 15min / ton~20min / ton;

[0017] S22 VD refining: transfer the refined molten steel to the VD vacuum furnace, heat it up, evacuate it to 45Pa~55Pa for degassing, blow nitrogen gas to break the vacuum, stir to increase nitrogen, feed calcium wire to get casting molten steel, and the refining time is 10min / ton~15min / ton;

[0018] S3 Continuous casting and rolling: Casting round billets are obtained by continuous casting of molten steel, and crystallization is carried out by electromagnetic ultrasonic stirring casting. The electromagnetic ultrasonic process is as follows: ultrasonic amplitude is 11μm~15μm, frequency is 40kHz~50kHz, sine-cosine alternation is performed 4 times; electromagnetic stirring amplitude is ±4mm, frequency is 150Hz~180Hz, and electromagnetic stirring current is 260A~270A; followed by three-stage rolling treatment: the starting temperature of the first stage rolling is 1000℃~1050℃, the reduction rate is 17%~19%, the starting temperature of the second stage rolling is 950℃~980℃, the reduction rate is 11%~14%, and the starting temperature of the third stage rolling is 920℃~940℃, and the reduction rate is 5%~8%, to obtain rolled round steel;

[0019] S4 Performance heat treatment: Rolled round steel is subjected to graded performance heat treatment; for the first-level heat treatment, the billet with a temperature of 850℃~900℃ after rolling is placed in an insulation slow cooling pit, covered with an insulation sealing cover, and treated at a slow cooling rate of 3℃ / h~5℃ / h for 10h~12h; for the second-level heat treatment, after the first-level heat treatment is completed, the insulation sealing cover is half-opened, and the treatment is carried out at a slow cooling rate of 8℃ / h~10℃ / h for 20h~24h; for the third-level heat treatment, after the second-level heat treatment is completed, the insulation sealing cover is fully opened, and the treatment is carried out at a slow cooling rate of 15℃ / h~25℃ / h for 40h~45h; then the rolled piece is taken out and naturally cooled to room temperature.

[0020] Preferably, in step S1, the smelting furnace is heated to 1580°C-1600°C to smelt the raw materials into molten iron.

[0021] Preferably, in step S21, the LF refining furnace is heated to 1700° C.-1730° C. for refining.

[0022] Preferably, in step S21, the blowing speed of argon gas is 225NL / min~300NL / min.

[0023] Preferably, in step S22, the VD vacuum furnace is heated to 1730°C-1750°C for refining.

[0024] Preferably, in step S22, the bottom blowing nitrogen speed is 260NL / min~290NL / min.

[0025] Preferably, in the step S3, the starting temperature of the first stage rolling is 1050°C, the reduction rate is 19%, the starting temperature of the second stage rolling is 980°C, the reduction rate is 14%, and the starting temperature of the third stage rolling is 940°C, the reduction rate is 8%; in the step S4, the first stage heat treatment is to treat the billet at a temperature of 900°C at a slow cooling rate of 5°C / h for 12h; the second stage heat treatment is to treat it at a slow cooling rate of 10°C / h for 24h; the third stage heat treatment is to treat it at a slow cooling rate of 25°C / h for 45h.

[0026] Preferably, in step S3, the starting temperature of the first stage rolling is 1000°C, the reduction rate is 17%, the starting temperature of the second stage rolling is 950°C, the reduction rate is 11%, and the starting temperature of the third stage rolling is 920°C, the reduction rate is 5%; in step S4, the first stage heat treatment is to treat the billet at a temperature of 850°C at a slow cooling rate of 3°C / h for 10 hours; the second stage heat treatment is to treat it at a slow cooling rate of 8°C / h for 20 hours; the third stage heat treatment is to treat it at a slow cooling rate of 15°C / h for 40 hours.

[0027] Preferably, in the step S3, the starting temperature of the first stage rolling is 1020°C, the reduction rate is 18%, the starting temperature of the second stage rolling is 970°C, the reduction rate is 12%, and the starting temperature of the third stage rolling is 930°C, the reduction rate is 6%; in the step S4, the first stage heat treatment is to treat the billet at a temperature of 880°C at a slow cooling rate of 4°C / h for 11 hours; the second stage heat treatment is to treat it at a slow cooling rate of 9°C / h for 22 hours; the third stage heat treatment is to treat it at a slow cooling rate of 20°C / h for 42 hours.

[0028] In a third aspect, the present invention provides a wind power bearing, which is made of the high-strength and toughness wind power bearing steel mentioned above or the high-strength and toughness wind power bearing steel obtained by the above-mentioned preparation method.

[0029] The present invention has the following technical effects or advantages:

[0030] The high-strength and high-toughness wind power bearing steel of the present invention has the advantages of both high strength and high toughness, and is suitable for the working conditions of wind power bearings.

[0031] The wind power bearing steel of the present invention can form a multi-level micro-nano precipitation phase in the microstructure of the wind power bearing steel through the coordinated regulation of specific component smelting, three-stage gradient rolling and four-stage variable temperature heat treatment, wherein the first-level precipitation phase is a coherent Cu-rich precipitation phase, and the second-level precipitation phase is a CuTi intermediate phase. Compared with the complex process requiring quenching, equivalent martensitic steel and carburizing steel requiring additional carburizing treatment, the preparation method is simple and controllable, and the product performance is stable.

[0032] The principles of its specific microstructure formation include:

[0033] (1) During the smelting and refining process, a specific proportion of Cu and Ti are added, and electromagnetic ultrasonic stirring is used to make the molten steel contact the wall of the crystallizer, which can repeatedly form crystal nuclei at the crystallization wall, release a large amount of latent heat of crystallization, and form fine grains. During the positive sliding time, the tensile stress of the billet shell acting under the curved moon surface can be reduced; during the negative sliding time, the billet pressure can be increased, forming a directional stress distribution and accelerating the diffusion of Cu and Ti.

[0034] (2) Through the three-stage gradient rolling deformation, the steel billet can form a gradient dislocation density, further refine the grains, and facilitate the formation of high-density defects, providing a gathering place for the diffusion of Cu and Ti, so that Cu and Ti gather at the dislocations and form a segregated zone at the grain boundary; the internal stress generated by the deformation provides a driving force for the generation of multi-level micro-nano precipitates.

[0035] (3) During the heat treatment of performance, the supersaturated Cu atoms in the matrix can quickly aggregate to form a Cu-rich segregation zone during the primary heat treatment, providing conditions for the precipitation of Cu-rich. During the secondary heat treatment, as the diffusion of Cu continues, the concentration of Cu at the grain boundary continues to increase, completing the transformation from the Cu-rich segregation zone to the Cu-rich precipitation phase, and maintaining a coherent relationship. During the tertiary heat treatment, the enriched Cu atoms diffuse to the Ti atoms and react with them, forming a CuTi intermediate phase on the primary precipitation phase (Cu-rich precipitation phase).

[0036] In summary, through the above steps, multi-level micro-nano precipitation phases are formed in the microstructure of wind power bearing steel. The first-level precipitation phase is a coherent Cu-rich precipitation phase, and the second-level precipitation phase is a CuTi intermediate phase, which can significantly improve the strength and toughness. Among them, the coherent Cu-rich precipitation phase can significantly reduce the precipitation nucleation barrier, reduce the incubation period, achieve rapid and high-density intracrystalline precipitation, and pin the grain boundaries of submicron grains in time; the driving force for the growth of the precipitation phase is the interface energy. Due to the low interface energy of the coherent interface, the precipitation phase is very stable and can continuously provide effective pinning pressure to obtain a stable ultrafine grain structure. Instantaneous high-density intracrystalline precipitation can inhibit the growth of submicron grains, and the precipitation phase does not restrict dislocation slip and luan crystal formation, and can achieve high strength and high ductility at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is the metallographic microstructure diagram of the wind power bearing steel of Example 1;

[0038] Figure 2 This is the metallographic microstructure diagram of the wind power bearing steel of comparative example 2. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with specific embodiments. It should be understood that the specific embodiments are only used to explain the present invention and are not used to limit the scope of protection of the present invention.

[0040] In the following examples, alloy performance testing, metallographic microstructure sample preparation, component analysis, etc. were analyzed and tested in accordance with GB / T228.1-2021, GB / T 13298-2015, GB / T 6394-2017, etc.

[0041] Example 1 A high-strength and toughness wind power bearing steel and its preparation

[0042] 1. Molten steel smelting

[0043] The smelting furnace is heated to 1600°C, the raw materials are smelted into molten iron, and after the C content in the molten iron reaches the standard, oxygen is blown and quicklime is added to slag and steel to obtain smelted steel.

[0044] 2. Refining outside the furnace

[0045] (1) The molten steel is transferred to an LF refining furnace, and then the temperature is raised to 1730°C, and titanium iron, copper iron, and chromium iron master alloys are added to adjust the composition. Argon gas with a flow rate of 350 NL / min is blown in for stirring, and aluminum wire is fed in for deoxidation and slag formation to obtain refined molten steel. The refining time is calculated as 19 min / ton.

[0046] (2) VD refining: The refined molten steel is transferred to a VD vacuum furnace, heated to 1750°C and then evacuated to 55 Pa for degassing. Nitrogen is blown from the bottom at a rate of 290 NL / min to break the vacuum, stir the molten steel and add nitrogen, and then calcium wire is fed to obtain casting molten steel. The refining time is 13 min / ton.

[0047] 3. Continuous casting and rolling

[0048] The molten steel is transferred to the casting crystallizer for continuous casting to obtain a casting round billet. The crystallization is carried out by electromagnetic ultrasonic stirring casting. The electromagnetic ultrasonic process is as follows: ultrasonic amplitude 14μm, frequency 50kHz, sine-cosine alternation 4 times, electromagnetic stirring amplitude ±4mm, frequency 180Hz, electromagnetic stirring current 270A.

[0049] Then three-stage rolling treatment is carried out, with the starting temperature of the first stage being 1050°C and the reduction rate being 19%, the starting temperature of the second stage being 980°C and the reduction rate being 14%, and the starting temperature of the third stage being 940°C and the reduction rate being 8%, to obtain rolled round steel.

[0050] 3.Performance heat treatment

[0051] The rolled round steel is subjected to graded performance heat treatment.

[0052] For the primary heat treatment, the billet at a temperature of 900°C after rolling is placed in an insulation slow cooling pit, covered with an insulation sealing cover, and treated at a slow cooling rate of 5°C / h for 12h.

[0053] For the secondary heat treatment, after the primary heat treatment is completed, half open the heat preservation and sealing cover, and treat at a slow cooling rate of 10℃ / h for 24h. For the tertiary heat treatment, after the secondary heat treatment is completed, fully open the heat preservation and sealing cover, and treat at a slow cooling rate of 25℃ / h for 45h. For the quaternary heat treatment, take out the rolled piece and let it cool naturally to room temperature in the air.

[0054] The element composition of the high-strength and toughness wind power bearing steel prepared by this process is calculated by mass percentage:

[0055] C: 0.19%; Si: 0.36%; Mn: 0.87%; Cu: 3.96%; Cr: 1.90%; Ni: 2.430%; Mo: 0.33%; V: 0.17%; Ti: 1.13%; N: 0.007%; Al: ≤0.015%; P: ≤0.005%; S: ≤0.005%; the balance is Fe and unavoidable impurities.

[0056] Example 2 A high-strength and toughness wind power bearing steel and its preparation

[0057] 1. Molten steel smelting

[0058] The smelting furnace is heated to 1580°C, the raw materials are smelted into molten iron, and after the C content in the molten iron reaches the standard, oxygen is blown and quicklime is added to slag and steel is tapped to obtain smelted steel.

[0059] 2. Refining outside the furnace

[0060] (1) The molten steel is transferred to an LF refining furnace, and then the temperature is raised to 1700°C, and titanium iron, copper iron, and chromium iron master alloys are added to adjust the composition. Argon gas with a flow rate of 225 NL / min is blown in for stirring, and aluminum wire is fed in for deoxidation and slag formation to obtain refined molten steel. The refining time is calculated as 15 min / ton.

[0061] (2) The refined molten steel is transferred to a VD vacuum furnace, heated to 1730°C and then evacuated to 45 Pa for degassing. Nitrogen is blown from the bottom at 260 NL / min to break the vacuum, stir the molten steel and add nitrogen, and then calcium wire is fed to obtain casting molten steel. The refining time is 10 min / ton.

[0062] 3. Continuous casting and rolling

[0063] The molten steel is transferred to the casting crystallizer for continuous casting to obtain a casting round billet. The crystallization is carried out by electromagnetic ultrasonic stirring casting. The electromagnetic ultrasonic process is as follows: ultrasonic amplitude 11μm, frequency 40kHz, sine-cosine alternation 4 times, electromagnetic stirring amplitude ±4mm, frequency 150Hz, electromagnetic stirring current 260A.

[0064] Then three-stage rolling treatment is carried out, the starting temperature of the first stage rolling is 1000℃, and the reduction rate is 17%; the starting temperature of the second stage rolling is 950℃, and the reduction rate is 11%; the starting temperature of the third stage rolling is 920℃, and the reduction rate is 5%, to obtain rolled round steel.

[0065] 4.Performance heat treatment

[0066] The rolled round steel is subjected to graded performance heat treatment:

[0067] For the primary heat treatment, the billet with a temperature of 850°C after rolling is placed in an insulation slow cooling pit, covered with an insulation sealing cover, and treated at a slow cooling rate of 3°C / h for 10h.

[0068] For the secondary heat treatment, after the primary heat treatment is completed, half open the heat preservation sealing cover and treat at a slow cooling rate of 8℃ / h for 20h. For the tertiary heat treatment, after the secondary heat treatment is completed, fully open the heat preservation sealing cover and treat at a slow cooling rate of 15℃ / h for 40h. For the quaternary heat treatment, take out the rolled piece and place it in the air to cool naturally to room temperature.

[0069] The element composition of the high-strength and toughness wind power bearing steel prepared by this process is calculated by mass percentage:

[0070] C: 0.13%; Si: 0.45%; Mn: 0.43%; Cu: 1.88%; Cr: 1.30%; Ni: 1.70%; Mo: 0.24%; V: 0.08%; Ti: 2.15%; N: 0.003%; Al: ≤0.015%; P: ≤0.005%; S: ≤0.005%; the balance is Fe and unavoidable impurities.

[0071] Example 3 A high-strength and toughness wind power bearing steel and its preparation

[0072] 1. Molten steel smelting

[0073] The smelting furnace is heated to 1590°C, the raw materials are smelted into molten iron, and after the C content in the molten iron reaches the standard, oxygen is blown and quicklime is added to slag and steel to obtain smelted steel.

[0074] 2. Refining outside the furnace

[0075] (1) The molten steel is transferred to an LF refining furnace, and then the temperature is raised to 1720°C, and titanium iron, copper iron, and chromium iron master alloys are added to adjust the composition. Argon gas with a flow rate of 300 NL / min is blown in for stirring, and aluminum wire is fed in for deoxidation and slag formation to obtain refined molten steel. The refining time is calculated as 17 min / ton.

[0076] (2) The refined molten steel is transferred to a VD vacuum furnace, heated to 1740°C and then evacuated to 50 Pa for degassing. Nitrogen is blown from the bottom at a rate of 275 NL / min to break the vacuum, stir the molten steel and add nitrogen, and then calcium wire is fed to obtain casting molten steel. The refining time is 12 min / ton.

[0077] 3. Continuous casting and rolling

[0078] The molten steel obtained from S2 is transferred to the casting crystallizer for continuous casting to obtain a casting round billet. The crystallization is carried out by electromagnetic ultrasonic stirring casting. The electromagnetic ultrasonic process is as follows: ultrasonic amplitude 13μm, frequency 45kHz, sine-cosine alternation 4 times, electromagnetic stirring amplitude ±4mm, frequency 165Hz, electromagnetic stirring current 265A.

[0079] Then three-stage rolling treatment is carried out, the starting temperature of the first stage is 1020℃, the reduction rate is 18%; the starting temperature of the second stage is 970℃, the reduction rate is 13%; the starting temperature of the third stage is 930℃, the reduction rate is 6%, and rolled round steel is obtained.

[0080] 4.Performance heat treatment

[0081] The rolled round steel is subjected to graded performance heat treatment.

[0082] Primary heat treatment: Place the billet with a temperature of 880°C after rolling in an insulation slow cooling pit, cover it with an insulation sealing cover, and treat it at a slow cooling rate of 4°C / h for 11 hours.

[0083] Secondary heat treatment: After the primary heat treatment is completed, half-open the heat-insulating sealing cover and treat at a slow cooling rate of 9°C / h for 22h.

[0084] Third-stage heat treatment: After the second-stage heat treatment is completed, the heat preservation sealing cover is fully opened and the treatment is carried out at a slow cooling rate of 20℃ / h for 42h. For the fourth-stage heat treatment, the rolled piece is taken out and placed in the air for natural cooling to room temperature.

[0085] The element composition of the high-strength and toughness wind power bearing steel prepared by this process is calculated by mass percentage:

[0086] C: 0.15%; Si: 0.41%; Mn: 0.66%; Cu: 2.53%; Cr: 1.6%; Ni: 2.01%; Mo: 0.28%; V: 0.11%; Ti: 1.95%; N: 0.005%; Al: ≤0.015%; P: ≤0.005%; S: ≤0.005%; the balance is Fe and unavoidable impurities.

[0087] Comparative Example 1 A wind power bearing steel and its preparation

[0088] The method of Example 1 was used for preparation, except that the rolling was carried out in one-stage (the starting temperature was 980° C. and the reduction ratio was 12%), and the other methods were the same as those of Example 1.

[0089] Comparative Example 2 A wind power bearing steel and its preparation

[0090] The method of Example 1 is used for preparation, except that the rolled round steel is quickly placed in a slow cooling pit after rolling, directly covered and sealed, cooled to room temperature and taken out (without the third-level performance heat treatment), and the rest is the same as Example 1.

[0091] Test item 1: Metallographic microstructure observation

[0092] Take wind turbine bearing steel samples and prepare metallographic structure samples for microscopic observation.

[0093] The microstructures of the wind power bearing steels of Examples 1 to 3 have obvious secondary precipitation phases, the interface between the primary precipitation phase and the matrix is ​​a completely coherent interface, and the grain size is 10. Typical metallographic microstructure diagrams are shown in FIG. Figure 1 . Figure 1 The metallographic microstructure of the wind power bearing steel of Example 1 is shown in FIG. Figure 1 It can be seen that:

[0094] (1) A multi-level precipitation phase structure is formed in the microstructure of the wind turbine bearing steel: matrix (light color), primary precipitation phase (light color) and secondary precipitation phase (dark color).

[0095] (2) The interface between the primary precipitated phase and the matrix of the wind turbine bearing steel is a completely coherent interface (the interface in the white frame can be seen from the high-resolution image on the right, where the atoms between the two phases correspond one to one, and is a completely coherent interface).

[0096] The microstructures of the wind power bearing steels of Comparative Examples 1 and 2 lack secondary precipitation phases, and the interface between the primary precipitation phase and the matrix is ​​not a completely coherent interface, and the grain size is 6. Typical metallographic microstructure diagrams are shown in Figure 2 . Figure 2 This is the metallographic microstructure diagram of the wind power bearing steel of comparative example 2. Figure 2 It can be seen from the figure that this wind power bearing steel has only primary precipitation phase and no secondary precipitation phase.

[0097] Test item 2: Performance test

[0098] Take wind turbine bearing steel samples and test their yield strength, tensile strength, impact toughness and elongation after fracture.

[0099] The results are shown in Table 1. The yield strength, tensile strength, impact toughness and elongation after fracture of the wind power bearing steels of Examples 1 to 3 are higher than those of the wind power bearing steels of the comparative example, and have obvious advantages in strength and toughness.

[0100] Table 1 Performance comparison and grain size of wind power bearing steel

[0101]

[0102] Test Item 3: Analysis of precipitated phase composition

[0103] The composition of the primary and secondary precipitation phases of each wind power bearing steel sample was tested. From the composition analysis results in Table 2, the primary precipitation phase is a Cu-rich precipitation phase, and the secondary precipitation phase is a CuTi metal compound. The Cu atomic ratio content of the primary precipitation phase is ≥80% (80.12%~80.37%); the CuTi atomic ratio content of the secondary precipitation phase is ≥95% (97.63%~98.19%).

[0104] Table 2 Analysis of precipitation phase composition of wind power bearing steel

[0105]

Claims

1. A high-strength and toughness wind power bearing steel, characterized in that: In terms of mass percentage, the element composition of the high-strength and toughness wind power bearing steel is: C: 0.13%~0.19%, Si: 0.36%~0.45%, Mn: 0.43%~0.87%, Cu: 1.88%~3.96%, Cr: 1.30%~1.90%, Ni: 1.70%~2.43%, Mo: 0.24%~0.33%, V: 0.08%~0.17%, Ti: 1.13%~2.15%, N: 0.003% ~0.007%, Al: ≤0.015%, P: ≤0.005%, S: ≤0.005%, and the balance is Fe and unavoidable impurities; there are Cu-rich primary precipitation phase and CuTi secondary precipitation phase in the microstructure matrix of the high-strength and toughness wind power bearing steel, the phase interface between the Cu-rich primary precipitation phase and the matrix is ​​a completely coherent interface, the Cu atomic ratio content of the Cu-rich primary precipitation phase is ≥80%; the CuTi atomic ratio content of the CuTi secondary precipitation phase is ≥95%.

2. The high-strength and toughness wind power bearing steel according to claim 1, characterized in that: The Cu atomic ratio content of the Cu-rich primary precipitated phase is 80.1% to 80.4%, and the CuTi atomic ratio content of the CuTi secondary precipitated phase is 97.6% to 98.2%.

3. The high-strength and toughness wind power bearing steel according to claim 1, characterized in that: In terms of mass percentage, the element composition of the high-strength and toughness wind power bearing steel is: C: 0.19%; Si: 0.36%; Mn: 0.87%; Cu: 3.96%; Cr: 1.90%; Ni: 2.430%; Mo: 0.33%; V: 0.17%; Ti: 1.13%; N: 0.007%; Al: ≤0.015%; P: ≤0.005%; S: ≤0.005%; the balance is Fe and unavoidable impurities.

4. The high-strength and toughness wind power bearing steel according to claim 1, characterized in that: In terms of mass percentage, the element composition of the high-strength and toughness wind power bearing steel is: C: 0.13%; Si: 0.45%; Mn: 0.43%; Cu: 1.88%; Cr: 1.30%; Ni: 1.70%; Mo: 0.24%; V: 0.08%; Ti: 2.15%; N: 0.003%; Al: ≤0.015%; P: ≤0.005%; S: ≤0.005%; the balance is Fe and unavoidable impurities.

5. The high-strength and toughness wind power bearing steel according to claim 1, characterized in that: In terms of mass percentage, the element composition of the high-strength and toughness wind power bearing steel is: C: 0.15%; Si: 0.41%; Mn: 0.66%; Cu: 2.53%; Cr: 1.6%; Ni: 2.01%; Mo: 0.28%; V: 0.11%; Ti: 1.95%; N: 0.005%; Al: ≤0.015%; P: ≤0.005%; S: ≤0.005%; the balance is Fe and unavoidable impurities.

6. The method for preparing high-strength and toughness wind power bearing steel according to claim 1, characterized in that: The following steps are involved: S1 Molten Steel Smelting: The smelting furnace is heated to smelt the raw materials into molten iron. After the C content of the molten iron reaches the standard, oxygen is blown and quicklime is added to slag and steel is tapped to obtain molten steel; S2 refining outside the furnace: including LF refining and VD refining: S21 LF refining: the smelted steel is transferred to the LF refining furnace, the temperature is raised, titanium iron, copper iron, chromium iron master alloy are added, argon is blown in for stirring, aluminum wire is fed for deoxidation and slag formation, and refined steel is obtained. The refining time is 15min / ton~20min / ton; S22 VD refining: transfer the refined molten steel to the VD vacuum furnace, heat it up, evacuate it to 45Pa~55Pa for degassing, blow nitrogen gas to break the vacuum, stir to increase nitrogen, feed calcium wire to get casting molten steel, and the refining time is 10min / ton~15min / ton; S3 Continuous casting and rolling: Casting round billets are obtained by continuous casting of molten steel, and crystallization is carried out by electromagnetic ultrasonic stirring casting. The electromagnetic ultrasonic process is as follows: ultrasonic amplitude is 11μm~15μm, frequency is 40kHz~50kHz, sine-cosine alternation is performed 4 times; electromagnetic stirring amplitude is ±4mm, frequency is 150Hz~180Hz, and electromagnetic stirring current is 260A~270A; followed by three-stage rolling treatment: the starting temperature of the first stage rolling is 1000℃~1050℃, the reduction rate is 17%~19%, the starting temperature of the second stage rolling is 950℃~980℃, the reduction rate is 11%~14%, and the starting temperature of the third stage rolling is 920℃~940℃, and the reduction rate is 5%~8%, to obtain rolled round steel; S4 Performance heat treatment: Rolled round steel is subjected to graded performance heat treatment; for the first-level heat treatment, the billet with a temperature of 850℃~900℃ after rolling is placed in an insulation slow cooling pit, covered with an insulation sealing cover, and treated at a slow cooling rate of 3℃ / h~5℃ / h for 10h~12h; for the second-level heat treatment, after the first-level heat treatment is completed, the insulation sealing cover is half-opened, and the treatment is carried out at a slow cooling rate of 8℃ / h~10℃ / h for 20h~24h; for the third-level heat treatment, after the second-level heat treatment is completed, the insulation sealing cover is fully opened, and the treatment is carried out at a slow cooling rate of 15℃ / h~25℃ / h for 40h~45h; then the rolled piece is taken out and naturally cooled to room temperature.

7. The method for preparing high-strength and toughness wind power bearing steel according to claim 6, characterized in that: In step S1, the smelting furnace is heated to 1580° C. to 1600° C. to smelt the raw materials into molten iron.

8. The method for preparing high-strength and toughness wind power bearing steel according to claim 6, characterized in that: In the step S21, the LF refining furnace is heated to 1700°C-1730°C for refining.

9. The method for preparing high-strength and toughness wind power bearing steel according to claim 6, characterized in that: In step S21, the blowing speed of argon gas is 225NL / min~300NL / min.

10. The method for preparing high-strength and high-toughness wind power bearing steel according to claim 6, characterized in that: In step S22, the VD vacuum furnace is heated to 1730°C-1750°C for refining.

11. The method for preparing high-strength and toughness wind power bearing steel according to claim 6, characterized in that: In step S22, the bottom blowing nitrogen speed is 260NL / min~290NL / min.

12. The method for preparing high-strength and toughness wind power bearing steel according to claim 6, characterized in that: In the step S3, the starting temperature of the first stage rolling is 1050°C, the reduction rate is 19%, the starting temperature of the second stage rolling is 980°C, the reduction rate is 14%, and the starting temperature of the third stage rolling is 940°C, the reduction rate is 8%; in the step S4, the first stage heat treatment is to treat the billet at a temperature of 900°C at a slow cooling rate of 5°C / h for 12h; the second stage heat treatment is to treat it at a slow cooling rate of 10°C / h for 24h; the third stage heat treatment is to treat it at a slow cooling rate of 25°C / h for 45h.

13. The method for preparing high-strength and toughness wind power bearing steel according to claim 6, characterized in that: In the step S3, the starting temperature of the first stage rolling is 1000°C, the reduction rate is 17%, the starting temperature of the second stage rolling is 950°C, the reduction rate is 11%, and the starting temperature of the third stage rolling is 920°C, the reduction rate is 5%; in the step S4, the first stage heat treatment is to treat the billet at a temperature of 850°C at a slow cooling rate of 3°C / h for 10 hours; the second stage heat treatment is to treat it at a slow cooling rate of 8°C / h for 20 hours; the third stage heat treatment is to treat it at a slow cooling rate of 15°C / h for 40 hours.

14. The method for preparing high-strength and toughness wind power bearing steel according to claim 6, characterized in that: In the step S3, the starting temperature of the first stage rolling is 1020°C, the reduction rate is 18%, the starting temperature of the second stage rolling is 970°C, the reduction rate is 12%, and the starting temperature of the third stage rolling is 930°C, the reduction rate is 6%; in the step S4, the first stage heat treatment is to treat the billet at a temperature of 880°C at a slow cooling rate of 4°C / h for 11 hours; the second stage heat treatment is to treat it at a slow cooling rate of 9°C / h for 22 hours; the third stage heat treatment is to treat it at a slow cooling rate of 20°C / h for 42 hours.

15. A wind power bearing, characterized in that: The wind power bearing is made of the high-strength and toughness wind power bearing steel described in any one of claims 1 to 5 or the high-strength and toughness wind power bearing steel obtained by a method for making high-strength and toughness wind power bearing steel described in any one of claims 6 to 14.

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