CN118996277B

CN118996277B - High-strength and high-toughness wind power bearing steel, preparation method, application and wind power bearing

Info

Publication number: CN118996277B
Application number: CN202411193306.3A
Authority: CN
Inventors: 许亮; 袁震; 俞颖; 巨佳
Original assignee: Zhenhong Heavy Industry Jiangsu Co ltd
Current assignee: Zhenhong Heavy Industry Jiangsu Co ltd
Priority date: 2024-08-28
Filing date: 2024-08-28
Publication date: 2025-02-18
Anticipated expiration: 2044-08-28
Also published as: CN118996277A

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

High-strength and high-toughness wind power bearing steel, preparation method, application and wind power bearing

Technical Field

The invention belongs to the technical field of alloy steel and metallurgy, and particularly relates to high-strength and high-toughness wind power bearing steel, a manufacturing method and application thereof, and a wind power bearing.

Background

In recent years, with the high emphasis of renewable energy development in the whole society, the wind power industry rapidly rises, and becomes an important component in an energy system. The large-scale development and utilization of wind power not only effectively relieves the situation of energy shortage, but also promotes the optimization and upgrading of the energy structure.

The performance of the wind power bearing steel, which is used as a core material in wind power generation equipment, is directly related to the safe operation and long-term stability of the whole wind power equipment. In the face of severe natural conditions such as extreme wind speed change, strong temperature difference fluctuation, high salinity ocean environment and continuous mechanical stress, the wind power bearing steel must have high strength and toughness mechanical properties, and ensure long-term stable operation of the wind turbine generator under high rotation speed and heavy load.

High speed rotation and large torque transfer are a major challenge faced by wind bearings during wind power generation. The large torque and axial forces generated by the rotation of the blades are transmitted through the main shaft to the bearings, which bear these loads by means of their inner steel raceways and rolling bodies. This requires that wind power bearing steels must possess extremely high tensile and yield strengths to ensure that no fracture or plastic deformation occurs under extreme conditions. The high-strength wind power bearing steel can effectively resist heavy load and impact, and ensures stable operation of wind power equipment under severe weather conditions. On the other hand, in actual operation of wind power plants, the bearings may suffer from momentary overloads or shocks due to unpredictable and abrupt changes in wind speed, which puts higher demands on the toughness of the wind power bearing steel, otherwise brittle fractures may occur in these abrupt situations, leading to failure or even damage of the whole wind power plant. Under the background, with the continuous improvement of the megawatt level of wind power, the requirements on the toughness of wind power gears and bearings are also continuously improved.

Accordingly, there is a need in the art to develop a high strength and toughness Gao Fengdian bearing steel to address the above-described problems.

Disclosure of Invention

Aiming at the problems, the invention aims to provide high-strength and high-toughness wind power bearing steel, a manufacturing method and application thereof and a wind power bearing.

The technical scheme of the invention is as follows:

According to the first aspect, the high-strength and high-toughness wind power bearing steel comprises the following elements in percentage by mass, wherein the balance of ：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%, is Fe and unavoidable impurities, a microstructure matrix of the high-strength and high-toughness wind power bearing steel is provided with a Cu-rich primary precipitation phase and a CuTi secondary precipitation phase, a 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 more than or equal to 80%, and the CuTi atomic ratio content of the CuTi secondary precipitation phase is more than or equal to 95%.

Preferably, the Cu atomic ratio content of the Cu-rich primary precipitation phase of the high-strength and high-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 high-toughness wind power bearing steel is 97.6% -98.2%.

Preferably, the element composition of the high-strength and high-toughness wind power bearing comprises ：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%; parts by mass of Fe and unavoidable impurities as the rest.

Preferably, the element composition of the high-strength and high-toughness wind power bearing comprises ：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%; parts by mass of Fe and unavoidable impurities as the rest.

Preferably, the element composition of the high-strength and high-toughness wind power bearing comprises ：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%; parts by mass of Fe and unavoidable impurities as the rest.

In a second aspect, the invention provides a method for manufacturing the high-strength and high-toughness wind power bearing steel, which comprises the following steps:

s1, smelting molten steel, namely smelting raw materials into molten iron by heating a smelting furnace, blowing oxygen after the content of molten iron C reaches the standard, and adding quicklime to perform slag-making tapping to obtain molten steel;

s2, external refining, namely LF refining and VD refining:

S21 LF refining, namely transferring molten steel into an LF refining furnace, heating, adding ferrotitanium, copper-iron and ferrochrome intermediate alloy, blowing argon into the furnace for stirring, feeding aluminum wires for deoxidizing and slagging to obtain refined molten steel, wherein the refining time is 15-20 min/ton;

S22 VD refining, namely transferring refined molten steel to a VD vacuum furnace, heating, vacuumizing to 45-55 Pa, degassing, blowing nitrogen at bottom to break vacuum, stirring to increase nitrogen, and feeding a calcium line to obtain cast molten steel, wherein the refining time is 10-15 min/ton;

S3, continuous casting and rolling, namely, continuously casting molten steel to obtain a casting round billet, and crystallizing by adopting electromagnetic ultrasonic stirring casting, wherein an ultrasonic amplitude is 11-15 mu m, sine-cosine alternation is carried out for 4 times within a frequency range of 40-50 kHz, an electromagnetic stirring amplitude is +/-4 mm, a frequency is 150-180 Hz, an electromagnetic stirring current is 260-270A, and then three rolling treatment are carried out, wherein the initial rolling temperature is 1000-1050 ℃, the rolling reduction rate is 17-19%, the initial rolling temperature is 950-980 ℃, the rolling reduction rate is 11-14%, and the initial rolling temperature is 920-940 ℃ and the rolling reduction rate is 5-8%, so as to obtain the rolled round steel;

S4, performing performance heat treatment, namely rolling round steel to perform grading performance heat treatment, performing primary heat treatment, placing a blank with the temperature of 850-900 ℃ after rolling in a heat preservation slow cooling pit, covering a heat preservation sealing cover, performing treatment for 10-12 hours at the slow cooling rate of 3-5 ℃ per hour, performing secondary heat treatment, performing half-open heat preservation sealing cover, performing treatment for 20-24 hours at the slow cooling rate of 8-10 ℃ per hour after the primary heat treatment is finished, performing tertiary heat treatment, performing full-open heat preservation sealing cover, performing treatment for 40-45 hours at the slow cooling rate of 15-25 ℃ per hour after the secondary heat treatment is finished, and taking out a rolled piece and naturally cooling to room temperature.

Preferably, in the step S1, the temperature of the smelting furnace is raised to 1580-1600 ℃ to smelt the raw materials into molten iron.

Preferably, in the step S21, the LF refining furnace is heated to 1700 ℃ to 1730 ℃ for refining.

Preferably, in the step S21, the argon gas is blown at a speed of 225NL/min to 300NL/min.

Preferably, in the step S22, the VD vacuum furnace is heated to 1730-1750 ℃ for refining.

Preferably, in the step S22, the bottom blowing nitrogen speed is 260 NL/min-290 NL/min.

Preferably, in the step S3, the initial temperature of the first stage rolling is 1050 ℃, the rolling reduction is 19%, the initial temperature of the second stage rolling is 980 ℃, the rolling reduction is 14%, the initial temperature of the third stage rolling is 940 ℃, the rolling reduction is 8%, in the step S4, the primary heat treatment is that blanks with the temperature of 900 ℃ are processed for 12 hours at a slow cooling rate of 5 ℃ per hour, the secondary heat treatment is that the blanks are processed for 24 hours at a slow cooling rate of 10 ℃ per hour, and the tertiary heat treatment is that the blanks are processed for 45 hours at a slow cooling rate of 25 ℃ per hour.

Preferably, in the step S3, the initial temperature of the first stage rolling is 1000 ℃, the rolling reduction is 17%, the initial temperature of the second stage rolling is 950 ℃, the rolling reduction is 11%, the initial temperature of the third stage rolling is 920 ℃, and the rolling reduction is 5%, in the step S4, the first stage heat treatment is that blanks with the temperature of 850 ℃ are processed for 10 hours at a slow cooling rate of 3 ℃ per hour, the second stage heat treatment is that blanks are processed for 20 hours at a slow cooling rate of 8 ℃ per hour, and the third stage heat treatment is that blanks are processed for 40 hours at a slow cooling rate of 15 ℃ per hour.

Preferably, in the step S3, the initial rolling temperature is 1020 ℃, the rolling reduction is 18%, the initial rolling temperature is 970 ℃, the rolling reduction is 12%, the initial rolling temperature is 930 ℃, the rolling reduction is 6%, in the step S4, the primary heat treatment is that blanks with the temperature of 880 ℃ are processed for 11 hours at the slow cooling rate of 4 ℃ per hour, the secondary heat treatment is that the blanks are processed for 22 hours at the slow cooling rate of 9 ℃ per hour, and the tertiary heat treatment is that the blanks are processed for 42 hours at the slow cooling rate of 20 ℃ per hour.

In a third aspect, the invention provides a wind power bearing, which is made of the high-strength and high-toughness wind power bearing steel or the high-strength and high-toughness wind power bearing steel obtained by the manufacturing method.

The invention has the following technical effects or advantages:

The high-strength and high-toughness wind power bearing steel has the advantages of high strength and high toughness, and is suitable for working conditions of wind power bearings.

According to the wind power bearing steel, a multistage micro-nano precipitated phase can be formed in a microstructure of the wind power bearing steel through the cooperative regulation and control of specific component smelting, three-stage gradient rolling and four-stage variable temperature heat treatment, wherein the first-stage precipitated phase is a coherent Cu-rich precipitated phase, and the second-stage precipitated phase is a CuTi intermediate phase. Compared with the martensitic steel which is complex in process and needs quenching and equivalent and the carburizing steel which needs additional carburizing treatment, the preparation method is simple and convenient and controllable, and the product performance is stable.

The principle of its specific microstructure formation includes:

(1) Cu and Ti with specific proportion are added in the smelting/refining process, electromagnetic ultrasonic stirring is adopted, so that molten steel and the wall of a crystallizer are in scouring contact, crystal nuclei can be formed at the position of the wall of the crystallizer continuously and repeatedly, a large amount of crystallization latent heat is released, and fine grains are formed. The blank shell tensile stress acting under the curved lunar surface can be reduced in the positive sliding time, and the blank pressure can be increased in the negative sliding time to form directional stress distribution so as to accelerate the diffusion of Cu and Ti.

(2) The steel billet can form gradient dislocation density through three-stage gradient rolling deformation, further refine grains, and facilitate the formation of high-density defects, provide a gathering place for Cu and Ti diffusion, gather Cu and Ti at the dislocation position, and form a segregation region at a grain boundary, and the internal stress generated by deformation provides driving force for the generation of a multi-stage micro-nano precipitated phase.

(3) In the process of the performance heat treatment, supersaturated Cu atoms in a matrix can be rapidly aggregated in the primary heat treatment process to form a Cu-rich segregation region, conditions are provided for Cu-rich precipitation, in the secondary heat treatment process, cu concentration at a crystal boundary is continuously increased along with Cu diffusion, the transition from the Cu-rich segregation region to a Cu-rich precipitation phase is completed, and a coherent relation is maintained, in the tertiary heat treatment process, the enriched Cu atoms diffuse to Ti atoms to react with the Ti atoms, and a CuTi intermediate phase is formed above the primary precipitation phase (Cu-rich precipitation phase).

In conclusion, through the steps, a multi-stage micro-nano precipitated phase is formed in the microstructure of the wind power bearing steel. Wherein the first-stage precipitated phase is a coherent Cu-rich precipitated phase, and the second-stage precipitated phase is a CuTi intermediate phase, so that the strength and toughness can be obviously improved. The coherent Cu-rich precipitated phase can obviously reduce the precipitated nucleation barrier, reduce the incubation period, realize rapid high-density intragranular precipitation and timely pinning of the grain boundary of submicron grains, and the long and large driving force of the precipitated phase is interface energy. The instantaneous high-density intragranular precipitation can inhibit submicron grain growth, and the precipitated phase does not limit dislocation slip and Luan Jing generation, so that high strength and high ductility can be realized simultaneously.

Drawings

FIG. 1 is a metallographic microstructure of a wind power bearing steel of example 1;

FIG. 2 is a metallographic microstructure of the wind power bearing steel of comparative example 2.

Detailed Description

The invention will be further illustrated with reference to specific examples. It should be understood that the detailed description is intended to illustrate the invention, but is not intended to limit the scope of the invention.

In the following examples, alloy performance test, metallographic microstructure sample preparation, component analysis and the like were carried out according to GB/T228.1-2021, GB/T13298-2015, GB/T6394-2017 and the like.

Example 1 high strength and toughness wind power bearing steel and preparation thereof

1. Molten steel smelting

Heating the smelting furnace to 1600 ℃, smelting the raw materials into molten iron, blowing oxygen after the content of C in the molten iron reaches the standard, and adding quicklime to perform slag-making tapping to obtain molten steel.

2. External refining

(1) Transferring the molten steel into an LF refining furnace, then heating to 1730 ℃, adding ferrotitanium, copper-iron and ferrochrome intermediate alloy, adjusting components, blowing argon with the flow of 350 NL/min for stirring, feeding aluminum wires for deoxidization and slagging, and obtaining refined molten steel, wherein the refining time is 19 min/ton.

(2) And (3) VD refining, namely transferring refined molten steel into a VD vacuum furnace, heating to 1750 ℃, vacuumizing to 55Pa, performing degassing treatment, then blowing 290NL/min nitrogen to break vacuum, stirring the molten steel, adding nitrogen, and then feeding a calcium line to obtain cast molten steel, wherein the refining time is 13 min/ton.

3. Continuous casting and rolling

The casting molten steel is continuously cast before being transferred to a casting crystallizer to obtain a casting round billet, and the casting is performed by adopting electromagnetic ultrasonic stirring casting, wherein the electromagnetic ultrasonic process is that the ultrasonic amplitude is 14 mu m, the sine and cosine are alternately performed for 4 times within the frequency range of 50kHz, the electromagnetic stirring amplitude is +/-4 mm, the frequency is 180Hz, and the electromagnetic stirring current is 270A.

And then three-stage rolling treatment is carried out, wherein the initial temperature of one stage of rolling is 1050 ℃, the rolling reduction is 19%, the initial temperature of the second stage of rolling is 980 ℃, the rolling reduction is 14%, the initial temperature of the three stages of rolling is 940 ℃, and the rolling reduction is 8%, so as to obtain the rolled round steel.

3. Performance heat treatment

And carrying out graded heat treatment on the rolled round steel.

And (3) primary heat treatment, namely placing the rolled blank with the temperature of 900 ℃ into a heat-preservation slow cooling pit, covering a heat-preservation sealing cover, and treating for 12 hours at the slow cooling rate of 5 ℃ per hour.

And (3) performing secondary heat treatment, after the primary heat treatment is finished, half-opening the heat-preserving sealing cover, and performing treatment for 24 hours at a slow cooling rate of 10 ℃ per hour. And (3) performing tertiary heat treatment, namely after the secondary heat treatment is finished, fully opening the heat-preserving sealing cover, and performing treatment for 45h at a slow cooling rate of 25 ℃ per hour. And carrying out four-stage heat treatment, taking out the rolled piece, and naturally cooling the rolled piece to room temperature in air.

The high-strength and high-toughness wind power bearing steel prepared by the process comprises the following elements in percentage by mass:

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 being Fe and unavoidable impurities.

Example 2 high strength and toughness wind power bearing steel and preparation thereof

1. Molten steel smelting

Heating the smelting furnace to 1580 ℃, smelting the raw materials into molten iron, blowing oxygen after the content of C in the molten iron reaches the standard, and adding quicklime to perform slag-making tapping to obtain molten steel.

2. External refining

(1) Transferring the molten steel into an LF refining furnace, then heating to 1700 ℃, adding ferrotitanium, copper-iron and ferrochrome intermediate alloy, adjusting components, blowing argon with the flow of 225 NL/min for stirring, feeding an aluminum wire for deoxidization and slagging to obtain refined molten steel, wherein the refining time is 15 min/ton.

(2) Transferring refined molten steel into a VD vacuum furnace, heating to 1730 ℃, vacuumizing to 45Pa, degassing, then blowing 260NL/min nitrogen to break vacuum, stirring the molten steel, adding nitrogen, and feeding a calcium line to obtain cast molten steel, wherein the refining time is 10 min/ton.

3. Continuous casting and rolling

The casting molten steel is continuously cast before being transferred to a casting crystallizer to obtain a casting round billet, the casting is cast by adopting electromagnetic ultrasonic stirring, and the electromagnetic ultrasonic process is that the ultrasonic amplitude is 11 mu m, the sine and cosine are alternately carried out for 4 times within the frequency range of 40kHz, the electromagnetic stirring amplitude is +/-4 mm, the frequency is 150Hz, and the electromagnetic stirring current is 260A.

And then three sections of rolling treatment are carried out, wherein the initial temperature of one section of rolling is 1000 ℃, the rolling reduction is 17%, the initial temperature of the second section of rolling is 950 ℃, the rolling reduction is 11%, the initial temperature of the three sections of rolling is 920 ℃, and the rolling reduction is 5%, so as to obtain the rolled round steel.

4. Performance heat treatment

Carrying out graded heat treatment on rolled round steel:

and (3) primary heat treatment, namely placing the rolled blank with the temperature of 850 ℃ in a heat-preservation slow cooling pit, covering a heat-preservation sealing cover, and treating for 10 hours at the slow cooling rate of 3 ℃ per hour.

And (3) performing secondary heat treatment, after the primary heat treatment is finished, half-opening the heat-preserving sealing cover, and treating for 20h at a slow cooling rate of 8 ℃ per hour. And (3) performing tertiary heat treatment, namely after the secondary heat treatment is finished, fully opening the heat-preserving sealing cover, and treating for 40 hours at a slow cooling rate of 15 ℃ per hour. And carrying out four-stage heat treatment, taking out the rolled piece, and naturally cooling the rolled piece to room temperature in air.

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 being Fe and unavoidable impurities.

Example 3 high strength and toughness wind power bearing steel and preparation thereof

1. Molten steel smelting

Heating the smelting furnace to 1590 ℃, smelting the raw materials into molten iron, blowing oxygen after the content of C in the molten iron reaches the standard, and adding quicklime to perform slag-making tapping to obtain molten steel.

2 Refining outside furnace

(1) Transferring the molten steel into an LF refining furnace, then heating to 1720 ℃, adding ferrotitanium, copper-iron and ferrochrome intermediate alloy, adjusting components, blowing argon with the flow of 300 NL/min for stirring, feeding aluminum wires for deoxidization and slagging to obtain refined molten steel, wherein the refining time is 17 min/ton.

(2) Transferring refined molten steel into a VD vacuum furnace, heating to 1740 ℃, vacuumizing to 50Pa, degassing, then blowing 275NL/min nitrogen to break vacuum, stirring the molten steel, adding nitrogen, and feeding a calcium line to obtain cast molten steel, wherein the refining time is 12 min/ton.

3. Continuous casting and rolling

And (3) transferring the casting molten steel obtained in the step (S2) to a pouring crystallizer, and performing continuous casting to obtain a casting round billet, wherein the casting is performed by adopting electromagnetic ultrasonic stirring, and the electromagnetic ultrasonic process comprises the steps of alternating sine and cosine for 4 times within the ultrasonic amplitude of 13 mu m and the frequency of 45kHz, and performing electromagnetic stirring with the amplitude of +/-4 mm, the frequency of 165Hz and the electromagnetic stirring current of 265A.

And then three sections of rolling treatment are carried out, wherein the initial temperature of one section of rolling is 1020 ℃, the rolling reduction is 18%, the initial temperature of the second section of rolling is 970 ℃, the rolling reduction is 13%, and the initial temperature of the three sections of rolling is 930 ℃, the rolling reduction is 6%, so as to obtain the rolled round steel.

4. Performance heat treatment

And carrying out graded heat treatment on the rolled round steel.

And (3) primary heat treatment, namely placing the rolled blank with the temperature of 880 ℃ into a heat-preservation slow cooling pit, covering a heat-preservation sealing cover, and treating for 11h at the slow cooling rate of 4 ℃ per hour.

And (3) secondary heat treatment, namely after the primary heat treatment is finished, half-opening the heat-preserving sealing cover, and treating for 22 hours at the slow cooling rate of 9 ℃ per hour.

And (3) performing tertiary heat treatment, namely fully opening the heat-preserving sealing cover after the secondary heat treatment is finished, and treating for 42h at a slow cooling rate of 20 ℃ per hour. And carrying out four-stage heat treatment, taking out the rolled piece, and naturally cooling the rolled piece to room temperature in air.

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 being Fe and unavoidable impurities.

Comparative example 1 wind power bearing steel and preparation thereof

Prepared as in example 1, except that rolling was performed in one pass (initial temperature 980 ℃ C., reduction 12%) as in example 1.

Comparative example 2 wind power bearing steel and preparation thereof

The process was carried out in the same manner as in example 1 except that the rolled round steel after rolling was rapidly placed in a pit, and the rolled round steel was directly capped, sealed and cooled to room temperature and taken out (without three-stage heat treatment).

Detection item 1 metallographic microstructure observation

And (3) taking a wind power bearing steel sample, preparing a metallographic structure sample, and carrying out microscopic observation.

The wind power bearing steel microstructures of examples 1 to 3 have obvious secondary precipitated phases, and the phase interface between the primary precipitated phases and the matrix is a completely coherent interface, and the grain size is 10. A typical metallographic microstructure is shown in fig. 1. FIG. 1 is a metallographic microstructure of a wind power bearing steel of example 1, as can be seen from FIG. 1:

(1) The wind power bearing steel microstructure forms a multi-stage precipitated phase structure, wherein the multi-stage precipitated phase structure comprises a matrix (light color), a primary precipitated phase (light color) and a secondary precipitated phase (dark color) respectively.

(2) The phase interface between the primary precipitation phase and the matrix of the wind power bearing steel is a completely coherent interface (the interface in the white block diagram can be seen from the right high-resolution diagram, and atoms between the two phases are in one-to-one correspondence, and the interface belongs to the completely coherent interface).

The microstructure of the wind power bearing steel of comparative example 1 and comparative example 2 lacks a secondary precipitated phase, and the phase interface between the primary precipitated phase and the matrix is not a completely coherent interface, and the grain size is 6. A typical metallographic microstructure is shown in fig. 2. FIG. 2 is a metallographic microstructure of the wind power bearing steel of comparative example 2, and it can be seen from FIG. 2 that the wind power bearing steel has only a primary precipitated phase and no secondary precipitated phase.

Test item 2 Performance test

And (3) taking a wind power bearing steel sample, and testing the yield strength, the tensile strength, the impact toughness and the elongation after fracture of the sample.

The results are shown in Table 1. The wind power bearing steels of examples 1 to 3 have higher yield strength, tensile strength, impact toughness and elongation after break than those of the wind power bearing steels of comparative examples, and have obvious advantages in terms of strength and toughness.

TABLE 1 wind bearing Steel Performance comparison and grain size

Detection item 3 analysis of precipitated phase Components

And respectively carrying out component test on the primary precipitated phase and the secondary precipitated phase of each wind power bearing steel sample. From the results of the component analysis in table 2, the first precipitated phase was a Cu-rich precipitated phase, and the second precipitated phase was a CuTi metal compound. The atomic ratio content of Cu in the first-stage precipitated phase is more than or equal to 80 percent (80.12 to 80.37 percent), and the atomic ratio content of CuTi in the second-stage precipitated phase is more than or equal to 95 percent (97.63 to 98.19 percent).

TABLE 2 analysis of precipitated phase composition of wind power bearing steel

Claims

1. A high-strength and high-toughness wind power bearing steel is characterized in that the high-strength and high-toughness wind power bearing steel comprises ：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%, percent of Fe and unavoidable impurities in percentage by mass, a microstructure matrix of the high-strength and high-toughness wind power bearing steel is provided with a Cu-rich primary precipitation phase and a CuTi secondary precipitation phase, a 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 more than or equal to 80 percent, and the CuTi atomic ratio content of the CuTi secondary precipitation phase is more than or equal to 95 percent.

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

3. The high-strength and high-toughness wind power bearing steel according to claim 1, wherein the high-strength and high-toughness wind power bearing steel comprises ：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%; parts by mass of Fe and unavoidable impurities as the balance.

4. The high-strength and high-toughness wind power bearing steel according to claim 1, wherein the high-strength and high-toughness wind power bearing steel comprises ：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%; parts by mass of Fe and unavoidable impurities as the balance.

5. The high-strength and high-toughness wind power bearing steel according to claim 1, wherein the high-strength and high-toughness wind power bearing steel comprises ：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%; parts by mass of Fe and unavoidable impurities as the balance.

6. The method for manufacturing high-strength and high-toughness wind power bearing steel according to claim 1, which is characterized by comprising the following steps:

s2, external refining, namely LF refining and VD refining:

7. The method for manufacturing high-strength and high-toughness wind power bearing steel according to claim 6, wherein in the step S1, the smelting furnace is heated to 1580-1600 ℃ to smelt raw materials into molten iron.

8. The method for manufacturing high strength and toughness wind power bearing steel according to claim 6, wherein in the step S21, the LF refining furnace is heated to 1700-1730 ℃ for refining.

9. The method for manufacturing high strength and toughness wind power bearing steel according to claim 6, wherein in the step S21, argon is blown at a speed of 225NL/min to 300NL/min.

10. The method for manufacturing high strength and toughness wind power bearing steel according to claim 6, wherein in the step S22, the VD vacuum furnace is heated to 1730-1750 ℃ for refining.

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

12. The method for manufacturing high strength and toughness wind power bearing steel according to claim 6, wherein in the step S3, the initial rolling temperature is 1050 ℃, the rolling reduction is 19%, the initial rolling temperature is 980 ℃, the rolling reduction is 14%, the initial rolling temperature is 940 ℃ and the rolling reduction is 8%, and in the step S4, the primary heat treatment is to treat a blank with the temperature of 900 ℃ at a slow cooling rate of 5 ℃ per hour for 12 hours, the secondary heat treatment is to treat the blank at a slow cooling rate of 10 ℃ per hour for 24 hours, and the tertiary heat treatment is to treat the blank at a slow cooling rate of 25 ℃ per hour for 45 hours.

13. The method for manufacturing high strength and toughness wind power bearing steel according to claim 6, wherein in the step S3, the initial rolling temperature is 1000 ℃, the rolling reduction is 17%, the initial rolling temperature is 950 ℃, the rolling reduction is 11%, the initial rolling temperature is 920 ℃ and the rolling reduction is 5%, the first-stage heat treatment is to treat a blank with a temperature of 850 ℃ at a slow cooling rate of 3 ℃ per hour for 10 hours, the second-stage heat treatment is to treat the blank at a slow cooling rate of 8 ℃ per hour for 20 hours, and the third-stage heat treatment is to treat the blank at a slow cooling rate of 15 ℃ per hour for 40 hours.

14. The method for manufacturing high strength and toughness wind power bearing steel according to claim 6, wherein in the step S3, the initial rolling temperature is 1020 ℃, the rolling reduction is 18%, the initial rolling temperature is 970 ℃, the rolling reduction is 12%, the initial rolling temperature is 930 ℃ and the rolling reduction is 6%, the first-stage heat treatment is that blanks with the temperature of 880 ℃ are processed at a slow cooling rate of 4 ℃ per hour for 11 hours, the second-stage heat treatment is that the slow cooling rate of 9 ℃ per hour is processed for 22 hours, and the third-stage heat treatment is that the slow cooling rate of 20 ℃ per hour is processed for 42 hours.

15. A wind power bearing, wherein the wind power bearing is made of the high-strength and toughness wind power bearing steel according to any one of claims 1 to 5 or the high-strength and toughness wind power bearing steel obtained by the method for manufacturing the high-strength and toughness wind power bearing steel according to any one of claims 6 to 14.