Alloy steel slewing bearing forge piece with characteristics of high toughness and hydrogen embrittlement resistance and manufacturing method thereof

Abstract

The invention discloses an alloy steel slewing bearing forge piece with the characteristics of high toughness and hydrogen embrittlement resistance and a manufacturing method of the alloy steel slewing bearing forge piece, and belongs to the technical field of metal forging and heat treatment. The forge piece is prepared from the following components in percentage by mass: 0.35 to 0.40 percent of C, 0.8 to 1.0 percent of Cr, 0.5 to 0.8 percent of Mo, 0.7 to 1.0 percent of Mn, 0.1 to 0.5 percent of Ti, 0.5 to 0.8 percent of Cu, 0.05 to 0.1 percent of Nb, 0.05 to 0.1 percent of V, 0.02 to 0.05 percent of Al and 0.001 to 0.008 percent of RE. The special alloy steel is designed, through the forging and heat treatment process, the slewing bearing forge piece tissue is tempered sorbite, fine equiaxed ferrite and micro-nano multi-scale deep hydrogen trap carbonitride, it is ensured that the alloy steel slewing bearing forge piece has excellent obdurability matching, and meanwhile the hydrogen embrittlement resistance of the alloy steel slewing bearing forge piece is remarkably improved.

Description

Technical Field

[0001] The invention relates to an alloy steel slewing bearing forging with high strength and toughness and hydrogen embrittlement resistance and a manufacturing method thereof, belonging to the technical field of metal forging and heat treatment. Background Art

[0002] New changes and new opportunities are constantly emerging in the new energy industry in various countries around the world. As an important part of renewable energy, the wind power industry is also one of the most mature and commercially developed power generation methods in the field of renewable energy. The wind power industry is gradually developing towards ultra-large power and complex environment. As key components of wind turbines, the working environment of large slewing bearings for pitch bearings and yaw towers is becoming increasingly harsh. The safe and stable operation of slewing bearings is the guarantee for the safe operation of wind turbines.

[0003] During the operation of slewing bearing forgings for ultra-large power wind turbines (13MW and above), they are mainly subjected to huge alternating loads and impact loads, and work in harsh environments such as low temperature, high altitude, wind, sand, and sea salt for a long time. Therefore, slewing bearing forgings must have high strength and toughness, as well as excellent impact resistance, wear resistance, and fatigue resistance. At present, the materials of slewing bearing forgings for wind turbines are mainly medium-carbon alloy steels such as 42CrMo and 42CrNiMo. In recent years, as wind turbines have developed towards ultra-large power, the diameter of slewing bearing forgings for wind turbines has reached 5 to 15 meters. The hydrogen-induced cracking phenomenon during the forging process of large slewing bearing forgings is the main cause of their premature damage and failure. In addition, when large forgings are in service under high stress, the migration and enrichment of hydrogen atoms will be accelerated, resulting in high hydrogen embrittlement sensitivity. Therefore, the properties of large slewing bearing forgings put forward higher requirements on the metallurgical technology and forging molding technology of the material. The publication number is CN Patent document 103103459A discloses a large wind power slewing bearing forging and its manufacturing process. The components and mass percentage (Wt%) of the slewing bearing forging material disclosed in the document are: C: 0.55-0.65%, Si: 0.65-0.75%, Mn: 0.55-0.65%, Ni: 0.2-0.4%, Cr: 2-4%, Nb: 0.15-0.25%, Cu: 0.05-0.08%, N: 0.08-0.09%, Mo: 0.15-0.18%, Al: 0.1-0.3%, S: 0.07-0. 09%, Ti: 0.01-0.03%, V: 0.7-0.9%, B: 0.008-0.009%, composite rare earth: 1-3%, the balance is Fe, and a heat treatment process for a slewing bearing forging is disclosed: two normalizing + one tempering + cooling. The large wind power slewing bearing forging obtained by this technology has a tensile strength of 900-1050MPa and an elongation after fracture of 13%, and the grain grade reaches level 4. However, the metallographic structure and low-temperature impact performance of the slewing bearing forging are not disclosed in the document, and it is difficult to ensure that the slewing bearing forging has excellent resistance to low-temperature impact and hydrogen embrittlement. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an alloy steel slewing bearing forging with high strength and toughness and hydrogen embrittlement resistance. The forging has excellent low-temperature impact resistance and hydrogen embrittlement resistance.

[0005] At the same time, the present invention provides a method for manufacturing an alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance.

[0006] At the same time, the present invention provides an alloy steel slewing bearing forging with high strength and toughness and hydrogen embrittlement resistance for use in variable pitch bearings and large slewing bearings for yaw towers.

[0007] At the same time, the present invention provides an alloy steel slewing bearing forging with high strength and toughness and hydrogen embrittlement resistance for use in ultra-high power wind turbines (>13MW).

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0009] The alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance includes the following components and their mass percentage contents: C: 0.35-0.40%, Cr: 0.8-1.0%, Mo: 0.5-0.8%, Mn: 0.7-1.0%, Ti: 0.1-0.5%, Cu: 0.5-0.8%, Nb: 0.05-0.1%, V: 0.05-0.1%, Al: 0.02-0.05%, RE: 0.001-0.008%, P≤50ppm, S≤10ppm, O≤20ppm, H≤2ppm; the balance is Fe and unavoidable impurities.

[0010] A method for manufacturing an alloy steel slewing bearing forging having high strength and toughness and hydrogen embrittlement resistance comprises the following steps:

[0011] S01, free forging: the initial forging temperature of free forging is 1200-1250℃, and the final forging temperature is 1050-1100℃;

[0012] S02, ring rolling forming: the ring rolling forging ratio is ≥3.5:1, and the graded ring rolling process is adopted;

[0013] The specific process of graded ring rolling is as follows:

[0014] The deformation of the first-stage ring rolling is controlled at 75% to 85%, the rolling speed is 0.5 to 1 m / s, and the final forging temperature of the first-stage ring rolling is not less than 1150°C;

[0015] The deformation of the secondary ring rolling is controlled at 15% to 25%, the rolling speed is 1.5 to 2 m / s, and the final forging temperature of the secondary ring rolling is controlled at 900°C to 950°C;

[0016] The interval between the first and second ring rolling is 120s to 180s;

[0017] When the temperature drops to 400-500℃, the three-stage ring rolling begins. The deformation of the three-stage ring rolling is controlled at 5%-10%, and the rolling speed is 1.0-1.5m / s.

[0018] S03, heat treatment: The heat treatment includes residual temperature annealing, sub-temperature quenching and tempering treatment steps;

[0019] The residual temperature annealing treatment step includes: heating the alloy steel support forging formed by ring rolling to 930-950° C., keeping the temperature for 2h-4h, and then cooling it with the furnace;

[0020] The sub-temperature quenching treatment step includes: heating the alloy steel support forging after residual temperature annealing to a critical temperature range of 780°C to 810°C, holding the temperature for 4h to 8h, and then quenching to room temperature;

[0021] The tempering treatment includes two tempering processes, and the specific steps include: in the first tempering, the alloy steel support forgings after sub-temperature quenching treatment are heated to 650-680°C, kept warm for 10h-15h and then air-cooled; the second tempering temperature is 600°C-650°C, kept warm for 5h-8h and then air-cooled.

[0022] Preferably, the outer ring diameter of the alloy steel support forging is 5 to 15 m.

[0023] The metallographic structure of the alloy steel slewing bearing forging after heat treatment is tempered troostite + fine equiaxed ferrite + micro-nano multi-scale deep hydrogen trap carbonitride.

[0024] Alloy steel slewing bearing forgings with high strength and toughness and hydrogen embrittlement resistance, room temperature tensile strength ≥1050MPa, yield strength ≥810MPa, room temperature impact absorption energy greater than 135A kv / J, -60℃ impact absorption energy greater than 35A kv / J.

[0025] Alloy steel slewing bearing forgings with high strength, toughness and hydrogen embrittlement resistance are used in variable pitch bearings and large slewing bearings for yaw towers.

[0026] The application of alloy steel slewing bearing forgings with high strength, toughness and resistance to hydrogen embrittlement in ultra-large power wind turbines.

[0027] Preferably, the ultra-high power is >13 MW.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The addition of Ti, Nb, Al, and V microalloying elements to the alloy steel slewing bearing forging of the present invention is beneficial to the precipitation of carbonitrides such as TiN, NbN, AlN, NbC, and VC, which serve as deep hydrogen traps to capture and limit the diffusion of hydrogen atoms, thereby reducing the risk of hydrogen embrittlement. On the other hand, the high-melting-point carbonitrides can effectively inhibit the grain growth behavior of the alloy steel during heating, refine the grains of the alloy steel slewing bearing forging, and significantly improve its strength and toughness.

[0030] (2) The present invention adopts a graded ring rolling process. The first-stage ring rolling produces a large deformation at a high temperature and a relatively low rolling speed. On the one hand, a complete dynamic recrystallization process is generated, which significantly refines the alloy steel grains. On the other hand, the relatively high temperature can ensure that elements such as Ti, Nb, Al, and V are completely dissolved in the austenite of the alloy steel. The second-stage ring rolling has a relatively low temperature and a relatively high rolling speed. The low deformation temperature and high deformation storage energy promote the dispersion and precipitation of high-melting-point nano-scale TiN, NbN, AlN, NbC, and VC carbonitrides, while inhibiting the growth of alloy steel grains. The third-stage ring rolling has a temperature lower than the recrystallization temperature of the alloy steel, which significantly increases the dislocation density of the alloy steel. The relatively low rolling deformation is conducive to the uniform distribution of dislocations around the dispersed precipitated carbonitrides, forming a dislocation system uniformly distributed along the rolling direction. The uniformly distributed dislocation system provides a channel for the diffusion of hydrogen atoms, forms a synergistic effect with the dispersed precipitated carbonitrides, enhances the aggregation effect of carbonitrides on hydrogen atoms, and promotes the uniform distribution of hydrogen atoms in the alloy steel, further improving the hydrogen embrittlement resistance of the alloy steel.

[0031] (3) Forging residual heat annealing + sub-temperature quenching + tempering process. Annealing treatment with the help of forging residual heat can not only save energy and reduce consumption, shorten the production process, but also ensure that the forgings obtain a balanced structure, eliminate the mixed crystal structure caused by the large deformation of ring rolling, and improve the uniformity of the forging structure; the sub-temperature quenching process can ensure that the ferrite structure of the alloy steel forgings is fully recrystallized to obtain equiaxed and fine ferrite grains, and at the same time ensure that the TiN, NbN, AlN, NbC, VC and other carbonitrides precipitated during the forging process are still distributed in the austenite, which can effectively inhibit the growth of martensite and further refine the structure; after the first tempering at 650-680℃ , the alloy steel structure is transformed into fine equiaxed ferrite + tempered troostite + dispersed carbonitride. In this process, martensite decomposes, and the formed carbides still retain the martensite morphology and are distributed in laths, resulting in stress concentration, which is easy to cause hydrogen atom aggregation and crack initiation, significantly reducing the plastic toughness of alloy steel forgings. Under this condition, the carbides in the forging structure are mainly M3C type carbides. This type of carbide has a simple orthorhombic crystal structure and its interface stress field is weak. It cannot effectively absorb hydrogen atoms, which is not conducive to the hydrogen embrittlement resistance of alloy steel forgings. The second tempering temperature is 600℃~650℃. At this temperature, M3C type carbides can be decomposed into M 23 C7 and MC type carbides, M 23 C7 is a deep hydrogen trap carbide that can effectively adsorb hydrogen atoms and inhibit the diffusion of hydrogen atoms. At the same time, the adsorption effect of MC-type carbides on hydrogen atoms is greater than that of M3C-type carbides and can assist in delaying the diffusion of hydrogen atoms. In addition, the micron-scale deep hydrogen carbides produced by secondary tempering and the nano-scale carbonitrides formed during the ring rolling process form multi-level carbonitride deep hydrogen traps, further enhancing the ability of the alloy steel forging to accommodate hydrogen atoms. Therefore, the alloy steel forging has excellent hydrogen embrittlement resistance.

[0032] The present invention provides an alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance and a manufacturing method thereof, namely, a heat treatment process of graded ring rolling forming + residual heat annealing / sub-temperature quenching / secondary tempering in coordination. The microstructure of the alloy steel slewing bearing forging is tempered troostite + fine equiaxed ferrite + micro-nano multi-scale deep hydrogen trap carbonitride, which ensures that the alloy steel slewing bearing forging has excellent strength and toughness while significantly improving its hydrogen embrittlement resistance and low-temperature impact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The metallographic structure diagram of the alloy steel slewing bearing forging obtained by the manufacturing method of the present invention;

[0034] Figure 2 The grain structure diagram of the alloy steel slewing bearing forging obtained by the manufacturing method of the present invention;

[0035] Figure 3 This is the SEM organization diagram of the alloy steel slewing bearing forging obtained by the manufacturing method of the present invention;

[0036] Figure 4 This is the TEM organization diagram of the alloy steel slewing bearing forging obtained by the manufacturing method of the present invention. DETAILED DESCRIPTION

[0037] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0038] Example 1

[0039] The alloy steel slewing bearing forging and the processing steps of the present embodiment are as follows:

[0040] The alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance has the following components and their mass percentage contents: C: 0.35%, Cr: 1.0%, Mo: 0.8%, Mn: 1.0%, Ti: 0.5%, Cu: 0.8%, Nb: 0.1%, V: 0.1%, Al: 0.05%, RE: 0.008%, P: 50ppm, S: 10ppm, O: 20ppm, H: 2ppm; the balance is Fe and unavoidable impurities.

[0041] A method for manufacturing an alloy steel slewing bearing forging having high strength and toughness and hydrogen embrittlement resistance comprises the following steps:

[0042] (1) Forging: ① The above components are made into alloy steel, and the alloy steel is forged by free forging. The initial forging temperature of the free forging is 1250℃ and the final forging temperature is 1100℃; ② The forged billet is subjected to graded ring rolling: the deformation of the first-level ring rolling is 85%, the rolling speed is 0.5m / s, the final forging temperature of the ring rolling is 1150℃, the deformation of the second-level ring rolling is 15%, the rolling speed is 2m / s, the final forging temperature of the ring rolling is controlled at 950℃, and the interval time between the first-level ring rolling and the second-level ring rolling is 180s. When the temperature drops to 400℃, the third-level ring rolling is started, the deformation is controlled at 10%, and the rolling speed is 1.5m / s.

[0043] (2) Post-forging heat treatment: ① The alloy steel support forgings formed by ring rolling are heated to 950℃, kept at this temperature for 4 hours, and then cooled in the furnace. ② The alloy steel support forgings after forging residual heat annealing are heated to 780℃, kept at this temperature for 4 hours, and then water-quenched to room temperature. ③ The alloy steel support forgings after sub-temperature quenching are heated to 650℃, kept at this temperature for 10 hours, and then air-cooled to room temperature, and then heated to 600℃ for the second time, kept at this temperature for 8 hours, and then air-cooled to room temperature, thus obtaining alloy steel slewing support forgings with high strength, toughness and hydrogen embrittlement resistance.

[0044] The alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance of this embodiment is used in large slewing bearings for variable pitch bearings and yaw towers.

[0045] The alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance of this embodiment is used in ultra-large power wind turbines (>13MW).

[0046] Example 2

[0047] The alloy steel slewing bearing forging and the processing steps of the present embodiment are as follows:

[0048] The alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance has the following components and their mass percentage contents: C: 0.40%, Cr: 0.8%, Mo: 0.5%, Mn: 0.7%, Ti: 0.1%, Cu: 0.5%, Nb: 0.05%, V: 0.05%, Al: 0.02%, RE: 0.001%, P: 35ppm, S: 8ppm, O: 15ppm, H: 1ppm; the balance is Fe and unavoidable impurities.

[0049] A method for manufacturing an alloy steel slewing bearing forging having high strength and toughness and hydrogen embrittlement resistance comprises the following steps:

[0050] (1) Forging: ① The above components are made into alloy steel, and the alloy steel is forged by free forging. The initial forging temperature of the free forging is 1200℃ and the final forging temperature is 1050℃; ② The forged billet is subjected to graded ring rolling: the deformation of the first-level ring rolling is 75%, the rolling speed is 1m / s, the final forging temperature of the ring rolling is 1180℃, the deformation of the second-level ring rolling is 25%, the rolling speed is 1.5m / s, the final forging temperature of the ring rolling is controlled at 900℃, and the interval time between the first-level ring rolling and the second-level ring rolling is 120s. When the temperature drops to 500℃, the third-level ring rolling is started, the deformation is controlled at 5%, and the rolling speed is 1m / s.

[0051] (2) Post-forging heat treatment: ① The alloy steel support forgings formed by ring rolling are heated to 930℃, kept at this temperature for 2 hours, and then cooled in the furnace. ② The alloy steel support forgings after forging residual heat annealing are heated to 810℃ and kept at this temperature for 8 hours, and then water-quenched to room temperature. ③ The alloy steel support forgings after sub-temperature quenching are heated to 680℃ and kept at this temperature for 15 hours, and then air-cooled to room temperature, and then heated to 650℃ for the second time, kept at this temperature for 5 hours, and then air-cooled to room temperature, thus obtaining alloy steel slewing support forgings with high strength, toughness and hydrogen embrittlement resistance.

[0052] The alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance of this embodiment is used in large slewing bearings for variable pitch bearings and yaw towers.

[0053] The alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance of this embodiment is used in ultra-large power wind turbines (>13MW).

[0054] Example 3

[0055] The alloy steel slewing bearing forging and the processing steps of the present embodiment are as follows:

[0056] The alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance has the following components and their mass percentages: C: 0.38%, Cr: 0.9%, Mo: 0.7%, Mn: 0.8%, Ti: 0.3%, Cu: 0.6%, Nb: 0.08%, V: 0.08%, Al: 0.04%, RE: 0.005%, P: 40ppm, S: 5ppm, O: 10ppm, H: 2ppm; the balance is Fe and unavoidable impurities.

[0057] A method for manufacturing an alloy steel slewing bearing forging having high strength and toughness and hydrogen embrittlement resistance comprises the following steps:

[0058] (1) Forging: ① The above components are made into alloy steel, and the alloy steel is forged by free forging. The initial forging temperature of the free forging is 1250℃ and the final forging temperature is 1100℃; ② The forged billet is subjected to graded ring rolling: the deformation of the first-level ring rolling is 80%, the rolling speed is 0.8m / s, the final forging temperature of the ring rolling is 1200℃, the deformation of the second-level ring rolling is 20%, the rolling speed is 1.8m / s, the final forging temperature of the ring rolling is controlled at 920℃, and the interval time between the first-level ring rolling and the second-level ring rolling is 150s. When the temperature drops to 450℃, the third-level ring rolling is started, the deformation is controlled at 8%, and the rolling speed is 1.2m / s.

[0059] (2) Post-forging heat treatment: ① The alloy steel support forgings formed by ring rolling are heated to 950℃, kept at this temperature for 3 hours, and then cooled in the furnace. ② The alloy steel support forgings after forging residual heat annealing are heated to 800℃, kept at this temperature for 5 hours, and then water-quenched to room temperature. ③ The alloy steel support forgings after sub-temperature quenching are heated to 650℃, kept at this temperature for 12 hours, and then air-cooled to room temperature, and then heated to 630℃ for the second time, kept at this temperature for 6 hours, and then air-cooled to room temperature, thus obtaining alloy steel slewing support forgings with high strength, toughness and hydrogen embrittlement resistance.

[0060] The alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance of this embodiment is used in large slewing bearings for variable pitch bearings and yaw towers.

[0061] The alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance of this embodiment is used in ultra-large power wind turbines (>13MW).

[0062] Comparative Example 1

[0063] The difference between this comparative example and Example 3 is that a two-stage ring rolling process is adopted: the deformation of the first-stage ring rolling is 80%, the rolling speed is 0.8 m / s, the final forging temperature of the ring rolling is 1200°C, the deformation of the second-stage ring rolling is 20%, the rolling speed is 1.8 m / s, the final forging temperature of the ring rolling is controlled at 920°C, and the interval time between the first and second ring rolling is 150s.

[0064] Comparative Example 2

[0065] The difference between this comparative example and Example 3 is that only one tempering is used, that is, the alloy steel support forging after sub-temperature quenching is heated to 650° C. and kept at this temperature for 12 hours, and then air-cooled to room temperature to obtain the alloy steel slewing support forging.

[0066] The microstructure and performance tests were conducted on the alloy steel slewing bearing forgings with high strength, toughness and hydrogen embrittlement resistance obtained in Examples 1 to 3 and Comparative Examples 1 to 2.

[0067] The tensile and impact properties of the samples were tested according to the national standards GB / T 228-2010 and GB / T229-2007. The test results are shown in Table 1.

[0068] Table 1 Mechanical properties of alloy steel forged brake discs obtained in various embodiments

[0069]

[0070] Samples were taken from the forgings of Example 1 to obtain the metallographic structure and grain morphology of the forgings. The test results are as follows: Figure 1 and Figure 2 As shown in Figure 2, a scanning electron microscope was used to detect its high-magnification metallographic structure. Figure 3 As shown in Figure 2, the morphology of carbonitrides in forgings was analyzed using transmission electron microscopy. Figure 4 shown.

[0071] As shown in Table 1, the mechanical parameters of the products of the above three embodiments are far higher than the requirements of the technical specifications when compared with the conventional wind power slewing bearings. The comprehensive mechanical properties of the manufactured forgings, especially the strength and toughness, are greatly improved, and the forgings have excellent low-temperature impact toughness.

[0072] Depend on Figure 1 to Figure 4 It can be seen from the organizational structure diagram of the slewing bearing forging that the manufacturing method disclosed in the present invention enables the alloy steel slewing bearing forging to obtain tempered troostite + fine equiaxed ferrite + micro-nano multi-scale deep hydrogen trap carbonitride, and the organizational structure is uniform. Combined with the excellent strength and toughness matching of the forging in Table 1, it can be seen that the forging has excellent hydrogen embrittlement resistance and low-temperature impact resistance.

[0073] It should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the present invention, various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed method should not be interpreted as reflecting the intention that the claimed invention requires more features than those expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in less than all of the features of the previously disclosed embodiments. Therefore, the claims that follow the detailed description are hereby expressly incorporated into the detailed description, with each claim itself serving as a separate embodiment of the present invention.

[0074] Although the present invention has been described according to a limited number of embodiments, it will be apparent to those skilled in the art, with the benefit of the above description, that other embodiments may be envisioned within the scope of the invention thus described. In addition, it should be noted that the language used in this specification is selected primarily for readability and didactic purposes, rather than for explaining or defining the subject matter of the present invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is illustrative, not restrictive, with respect to the scope of the present invention, which is defined by the appended claims.

[0075] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Alloy steel slewing bearing forging with high strength and toughness and hydrogen embrittlement resistance, characterized in that: The invention comprises the following components and their mass percentage contents: C: 0.35-0.40%, Cr: 0.8-1.0%, Mo: 0.5-0.8%, Mn: 0.7-1.0%, Ti: 0.1-0.5%, Cu: 0.5-0.8%, Nb: 0.05-0.1%, V: 0.05-0.1%, Al: 0.02-0.05%, RE: 0.001-0.008%, P≤50ppm, S≤10ppm, O≤20ppm, H≤2ppm; the balance is Fe and unavoidable impurities.

2. The method for manufacturing an alloy steel slewing bearing forging with high strength and toughness and hydrogen embrittlement resistance according to claim 1, characterized in that: The following steps are involved: S01, free forging: the initial forging temperature of free forging is 1200-1250℃, and the final forging temperature is 1050-1100℃; S02, ring rolling forming: the ring rolling forging ratio is ≥3.5:1, and the graded ring rolling process is adopted; The specific process of graded ring rolling is as follows: The deformation of the first-stage ring rolling is controlled at 75% to 85%, the rolling speed is 0.5 to 1 m / s, and the final forging temperature of the first-stage ring rolling is not less than 1150°C; The deformation of the secondary ring rolling is controlled at 15% to 25%, the rolling speed is 1.5 to 2 m / s, and the final forging temperature of the secondary ring rolling is controlled at 900°C to 950°C; The interval between the first and second ring rolling is 120s to 180s; When the temperature drops to 400-500℃, the three-stage ring rolling begins. The deformation of the three-stage ring rolling is controlled at 5%-10%, and the rolling speed is 1.0-1.5m / s. S03, heat treatment: The heat treatment includes residual temperature annealing, sub-temperature quenching and tempering treatment steps; The residual temperature annealing treatment step includes: heating the alloy steel support forging formed by ring rolling to 930-950° C., keeping the temperature for 2h-4h, and then cooling it with the furnace; The sub-temperature quenching treatment step includes: heating the alloy steel support forging after residual temperature annealing to a critical temperature range of 780°C to 810°C, holding the temperature for 4h to 8h, and then quenching to room temperature; The tempering treatment includes two tempering processes, and the specific steps include: in the first tempering, the alloy steel support forgings after sub-temperature quenching treatment are heated to 650-680°C, kept warm for 10h-15h and then air-cooled; the second tempering temperature is 600°C-650°C, kept warm for 5h-8h and then air-cooled.

3. The manufacturing method according to claim 2, characterized in that: The outer ring diameter of the alloy steel support forging is 5 to 15m.

4. The alloy steel slewing bearing forging with high strength and toughness and hydrogen embrittlement resistance obtained by the manufacturing method according to claim 2 is characterized in that: The metallographic structure of the alloy steel slewing bearing forging after heat treatment is tempered troostite + fine equiaxed ferrite + micro-nano multi-scale deep hydrogen trap carbonitride.

5. The alloy steel slewing bearing forging with high strength and toughness and hydrogen embrittlement resistance according to claim 4 is characterized in that: Room temperature tensile strength ≥1050MPa, yield strength ≥810MPa, room temperature impact absorption energy greater than 135A kv / J, -60℃ impact absorption energy greater than 35A kv / J.

6. Application of the alloy steel slewing bearing forging with high strength and toughness and hydrogen embrittlement resistance according to claim 1 in large slewing bearings for variable pitch bearings and yaw towers.

7. Application of the alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance according to claim 1 in ultra-high power wind turbines.

8. The use according to claim 7, characterized in that: The maximum power is >13MW.

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