Alloy steel slewing bearing forgings with high strength, toughness and hydrogen embrittlement resistance and manufacturing method thereof

Abstract

The present invention discloses an alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance and its manufacturing method, belonging to the technical field of metal forging and heat treatment. The forging 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%. The present invention designs a special alloy steel. Through forging and heat treatment processes, the structure of the slewing bearing forging is tempered sorbite + fine equiaxed ferrite + micro-nano multi-scale deep hydrogen trap carbonitrides, ensuring excellent strength and toughness matching of the alloy steel slewing bearing forging and significantly improving its hydrogen embrittlement resistance.

Description

Technical Field

[0001] The present invention relates to an alloy steel slewing bearing forging with high strength, 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 reforms and opportunities are emerging continuously in the new energy industries of various countries in the world. As an important part of renewable energy, the wind power industry is also one of the most mature power generation methods with the conditions for large-scale development and commercial development prospects in the field of renewable energy. The wind power industry is gradually developing towards ultra-large power and environmental complexity. As key components of wind turbines, the working conditions of pitch bearings and large slewing bearings for yaw towers are becoming increasingly harsh. The safe and stable operation of slewing bearings is the guarantee for the safe operation of wind turbines.

[0003] Slewing bearing forgings for extra-large power wind turbines (above 13 MW) mainly bear huge alternating loads and impact loads during operation, and work in harsh environments such as low temperature, high altitude, wind, sand, and sea salt for a long time. Therefore, the slewing bearing forgings must have high strength and toughness characteristics, as well as excellent impact resistance, wear resistance, and fatigue resistance. At present, the materials of slewing bearing forgings for wind turbines mainly consist of medium-carbon alloy steels such as 42CrMo and 42CrNiMo. In recent years, with the development of wind turbines towards extra-large power, the diameter of slewing bearing forgings for wind turbines has reached 5 - 15 meters. The phenomenon of hydrogen-induced cracking during the forging process of large slewing bearing forgings is the main reason for their premature damage and failure. In addition, when large forgings are in service under high stress conditions, it will accelerate the migration and enrichment of hydrogen atoms, resulting in high hydrogen embrittlement sensitivity characteristics. Therefore, large slewing bearing forgings pose higher requirements for the metallurgical technology and forging forming technology of materials. The patent document with the publication number CN 103103459A discloses a large wind power slewing bearing forging and its manufacturing process. The components and mass percentages (Wt%) of the slewing bearing forging material disclosed in this 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%, A1: 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%, and the balance is Fe. It also discloses the heat treatment process of the slewing bearing forging: two normalizations + one tempering + cooling. The large wind power slewing bearing forging obtained by this technology has a tensile strength of 900 - 1050 MPa and an elongation after fracture of 13%, and the grain grade reaches level 4. However, the patent document does not disclose the metallographic structure and low-temperature impact performance of the slewing bearing forging, making it difficult to ensure that the slewing bearing forging has excellent low-temperature impact resistance and hydrogen embrittlement resistance characteristics. 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, toughness, and hydrogen embrittlement resistance characteristics, which has excellent low-temperature impact resistance and hydrogen embrittlement resistance characteristics.

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

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

[0007] Meanwhile, the present invention provides an application of a steel alloy slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance in an ultra-large power wind turbine (>13MW).

[0008] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0009] The steel alloy slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance 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 inevitable impurities.

[0010] The manufacturing method of the steel alloy slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance comprises the following steps:

[0011] S01, open-die forging to produce billet: The initial forging temperature for open-die forging to produce billet is 1200 - 1250°C, and the final forging temperature is 1050 - 1100°C;

[0012] S02, ring rolling forming: The forging ratio of ring rolling is ≥3.5:1, and a stepped ring rolling process is adopted;

[0013] The stepped ring rolling process is specifically as follows:

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

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

[0016] The interval time between the first-stage ring and the second-stage ring is 120s - 180s;

[0017] When the temperature drops to 400 - 500°C, the third-stage ring rolling is started. The deformation amount of the third-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 steps of soaking annealing, subcritical quenching and tempering treatment;

[0019] The steps of post-warmth annealing treatment include: reheating the formed alloy steel support forging by ring rolling to 930 - 950 °C, holding for 2 - 4 hours and then cooling with the furnace;

[0020] The steps of subcritical quenching treatment include: heating the alloy steel support forging after post-warmth annealing to the critical temperature range of 780 °C - 810 °C, holding for 4 - 8 hours and then quenching to room temperature;

[0021] The tempering treatment includes two tempering processes. The specific steps include: for the first tempering, heating the alloy steel support forging after subcritical quenching treatment to 650 - 680 °C, holding for 10 - 15 hours and then air cooling; for the second tempering, the temperature is 600 °C - 650 °C, holding for 5 - 8 hours and then air cooling.

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

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

[0024] The alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance has a room temperature tensile strength ≥ 1050 MPa, a yield strength ≥ 810 MPa, a room temperature impact absorption energy greater than 135 A kv / J, and an impact absorption energy at -60 °C greater than 35 A kv / J.

[0025] The application of the alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance in large slewing bearings for pitch bearings and yaw towers.

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

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

[0028] Compared with the prior art, the beneficial effects of the present invention are:

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

[0030] (2) The present invention adopts a hierarchical ring rolling process. In the first-stage ring rolling, a large deformation amount is generated at a high temperature and a relatively low rolling speed. On the one hand, a complete dynamic recrystallization process occurs, significantly refining the grains of the alloy steel. 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. In the second-stage ring rolling, the temperature is relatively low and the rolling speed is relatively high. The low deformation temperature and high deformation stored energy promote the dispersion precipitation of high-melting-point nanoscale TiN, NbN, AlN, NbC, and VC carbonitrides, and at the same time inhibit the growth of alloy steel grains. In the third-stage ring rolling, the temperature is lower than the recrystallization temperature of the alloy steel, significantly increasing the dislocation density of the alloy steel. The relatively low rolling deformation amount is conducive to the uniform distribution of dislocations around the dispersed carbonitrides, forming a dislocation system uniformly distributed along the rolling direction. This uniformly distributed dislocation system provides a channel for the diffusion of hydrogen atoms, forms a synergistic effect with the dispersed carbonitrides, enhances the aggregation effect of carbonitrides on hydrogen atoms, and at the same time promotes the uniform distribution of hydrogen atoms in the alloy steel, further improving the hydrogen embrittlement resistance of the alloy steel.

[0031] (3) The forging residual heat annealing + subcritical quenching + tempering process. Annealing with the forging residual heat can not only save energy and reduce consumption and 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 microstructure uniformity of the forgings. The subcritical quenching process can ensure that the ferrite structure of the alloy steel forgings undergoes sufficient recrystallization to obtain equiaxed 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 microstructure. After the first tempering at 650 - 680 °C, the structure of the alloy steel transforms into fine equiaxed ferrite + tempered sorbite + dispersed carbonitrides. During this process, martensite decomposes, and the formed carbides still retain the martensite morphology and are distributed in a lath shape, generating stress concentration, which is likely to cause the aggregation of hydrogen atoms and the initiation of cracks, significantly reducing the plasticity and toughness of the alloy steel forgings. And 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 interfacial stress field is weak, unable to effectively adsorb hydrogen atoms, which is not conducive to the hydrogen embrittlement resistance of the alloy steel forgings. The second tempering temperature is 600 °C - 650 °C. At this temperature, the M3C-type carbides can decompose into M 23 C7 and MC-type carbides. M 23 C7 is a deep hydrogen trap carbide, which can effectively adsorb hydrogen atoms and inhibit the diffusion of hydrogen atoms. At the same time, the MC-type carbides have a greater adsorption effect on hydrogen atoms than the M3C-type carbides and can assist in delaying the diffusion of hydrogen atoms. In addition, the micron-scale deep hydrogen carbides generated by the secondary tempering and the nanoscale carbonitrides formed during the ring rolling process form a multi-level carbonitride deep hydrogen trap, further enhancing the ability of the alloy steel forgings to accommodate hydrogen atoms. Therefore, the alloy steel forgings have excellent hydrogen embrittlement resistance characteristics.

[0032] The present invention provides an alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance characteristics and its manufacturing method, namely a heat treatment process combining step-by-step ring rolling forming + residual heat annealing / subcritical quenching / secondary tempering. The structure of the alloy steel slewing bearing forging is tempered sorbite + fine equiaxed ferrite + micro-nano multi-scale deep hydrogen trap carbonitrides, ensuring excellent strength and toughness of the alloy steel slewing bearing forging while significantly improving its hydrogen embrittlement resistance and low-temperature impact resistance. Brief Description of the Drawings

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

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

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

[0036] Figure 4 It is the TEM structure diagram of the alloy steel slewing bearing forging obtained by the manufacturing method of the present invention. Detailed Embodiments

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

[0038] Embodiment 1

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

[0040] An alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance characteristics, the components and their mass percentage contents are: 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: 50 ppm, S: 10 ppm, O: 20 ppm, H: 2 ppm; the balance is Fe and unavoidable impurities.

[0041] A manufacturing method of an alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance characteristics, comprising the following steps:

[0042] (1)Forging and forming: ① Make the above components into alloy steel. The alloy steel is initially forged and billeted by open-die forging. The initial forging temperature for open-die forging is 1250 °C, and the final forging temperature is 1100 °C. ② Perform stepped ring rolling on the above forged billets for forming: The deformation amount in the first-stage ring rolling is 85%, the rolling speed is 0.5 m / s, and the final forging temperature for ring rolling is 1150 °C. The deformation amount in the second-stage ring rolling is 15%, the rolling speed is 2 m / s, and the final forging temperature for ring rolling is controlled at 950 °C. The interval time between the first-stage ring rolling and the second-stage ring rolling is 180 s. When the temperature drops to 400 °C, start the third-stage ring rolling, and the deformation amount is controlled at 10%, and the rolling speed is 1.5 m / s.

[0043] (2)Post-forging heat treatment: ① Reheat the alloy steel support forgings formed by the above ring rolling to 950 °C, hold for 4 h, and then cool in the furnace. ② Heat the alloy steel support forgings after forging heat treatment annealing to 780 °C, hold for 4 h, and then water quench to room temperature. ③ Heat the alloy steel support forgings after subcritical quenching to 650 °C, hold for 10 h, and then air cool to room temperature. Subsequently, heat to 600 °C for the second time, hold for 8 h, and then air cool to room temperature, thus obtaining alloy steel slewing ring forgings with high strength, toughness, and hydrogen embrittlement resistance.

[0044] The application of the alloy steel slewing ring forgings with high strength, toughness, and hydrogen embrittlement resistance in this embodiment in variable pitch bearings and large slewing rings for yaw towers.

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

[0046] Example 2

[0047] The alloy steel slewing ring forgings in this embodiment and their processing steps are as follows:

[0048] Alloy steel slewing ring forgings with high strength, toughness, and hydrogen embrittlement resistance, with 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: 35 ppm, S: 8 ppm, O: 15 ppm, H: 1 ppm; the balance is Fe and unavoidable impurities.

[0049] A manufacturing method for alloy steel slewing ring forgings with high strength, toughness, and hydrogen embrittlement resistance, comprising the following steps:

[0050] (1)Forging and forming: ① Make the above components into alloy steel. The alloy steel is initially forged and billeted by open-die forging. The initial forging temperature is 1200 °C, and the final forging temperature is 1050 °C. ② Subject the above forged billet to stepped ring rolling for forming: The deformation amount of the first-stage ring rolling is 75%, the rolling speed is 1 m / s, and the final forging temperature of the ring rolling is 1180 °C. The deformation amount of the second-stage ring rolling is 25%, the rolling speed is 1.5 m / s, and the final forging temperature of the ring rolling is controlled at 900 °C. The interval time between the first-stage ring rolling and the second-stage ring rolling is 120 s. When the temperature drops to 500 °C, start the third-stage ring rolling, and the deformation amount is controlled at 5%, and the rolling speed is 1 m / s.

[0051] (2)Post-forging heat treatment: ① Reheat the alloy steel support forging formed by the above ring rolling to 930 °C, hold for 2 h, and then cool with the furnace. ② Heat the alloy steel support forging after forging and annealing with residual heat to 810 °C, hold for 8 h, and then water quench to room temperature. ③ Heat the alloy steel support forging after subcritical quenching to 680 °C, hold for 15 h, and then air cool to room temperature. Subsequently, heat it to 650 °C for the second time, hold for 5 h, and then air cool to room temperature, thus obtaining an alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance.

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

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

[0054] Example 3

[0055] The alloy steel slewing bearing forging in this embodiment and its processing steps are as follows:

[0056] An alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance, and the mass percentage content of each component is: 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: 40 ppm, S: 5 ppm, O: 10 ppm, H: 2 ppm; the balance is Fe and unavoidable impurities.

[0057] A manufacturing method of an alloy steel slewing bearing forging with high strength, toughness and hydrogen embrittlement resistance, comprising the following steps:

[0058] (1)Forging and forming: ① Make the above components into alloy steel. The alloy steel is initially forged and billeted by open-die forging. The initial forging temperature is 1250 °C, and the final forging temperature is 1100 °C. ② Perform step-by-step ring rolling on the above forged billets: The deformation amount of the first-stage ring rolling is 80%, the rolling speed is 0.8 m / s, and the final forging temperature of the ring rolling is 1200 °C. The deformation amount of the second-stage ring rolling is 20%, the rolling speed is 1.8 m / s, and the final forging temperature of the ring rolling is controlled at 920 °C. The interval time between the first-stage ring rolling and the second-stage ring rolling is 150 s. When the temperature drops to 450 °C, start the third-stage ring rolling, and the deformation amount is controlled at 8%, and the rolling speed is 1.2 m / s.

[0059] (2)Post-forging heat treatment: ① Reheat the alloy steel support forgings formed by the above ring rolling to 950 °C, keep them warm for 3 h, and then cool them in the furnace. ② Heat the alloy steel support forgings after forging heat treatment annealing to 800 °C, keep them warm for 5 h, and then water-quench them to room temperature. ③ Heat the alloy steel support forgings after subcritical quenching to 650 °C, keep them warm for 12 h, and then air-cool them to room temperature. Subsequently, heat them to 630 °C for the second time, keep them warm for 6 h, and then air-cool them to room temperature, thus obtaining alloy steel slewing ring forgings with high strength, toughness and hydrogen embrittlement resistance characteristics.

[0060] The application of the alloy steel slewing ring forgings with high strength, toughness and hydrogen embrittlement resistance characteristics in this embodiment in variable pitch bearings and large slewing rings for yaw towers.

[0061] The application of the alloy steel slewing ring forgings with high strength, toughness and hydrogen embrittlement resistance characteristics in this embodiment in ultra-large power wind turbines (>13 MW).

[0062] Comparative Example 1

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

[0064] Comparative Example 2

[0065] The difference between this comparative example and Example 3 is only that: Only one tempering is adopted, that is, heat the alloy steel support forgings after subcritical quenching to 650 °C, keep them warm for 12 h, and then air-cool them to room temperature to obtain alloy steel slewing ring forgings.

[0066] Conduct microstructure and property tests on the alloy steel slewing ring forgings with high strength, toughness and hydrogen embrittlement resistance characteristics obtained in Examples 1-3 and Comparative Examples 1-2.

[0067] The tensile and impact properties of the test specimens were tested according to the national standards GB / T 228-2010 and GB / T 229-2007, and the test results are shown in Table 1.

[0068] Table 1 Mechanical properties of alloy steel forged brake discs obtained in each example

[0069]

[0070] Samples were taken from the forgings of Example 1 to obtain the metallographic structure and grain morphology diagrams of the forgings. The test results are as Figure 1 and Figure 2 shown. At the same time, the high-magnification metallographic structure was detected using a scanning electron microscope, as Figure 3 shown. The morphology of carbonitrides in the forgings was analyzed using a transmission electron microscope, as Figure 4 shown.

[0071] As can be seen from Table 1, when the products of the above three examples were compared with conventional wind power slewing bearings, the mechanical parameters of the products obtained by the present invention were far higher than the requirements of the technical specifications. The comprehensive mechanical properties of the manufactured forgings, especially the strength and toughness, were greatly improved, and they had excellent low-temperature impact toughness.

[0072] From Figures 1 to 4 the organizational structure diagram of the slewing bearing forgings, it can be seen that the manufacturing method disclosed by the present invention enables the alloy steel slewing bearing forgings to obtain tempered sorbite + fine equiaxed ferrite + micro-nano multi-scale deep hydrogen trap carbonitrides, and the organizational structure is uniform. Combining with the excellent strength and toughness matching of the forgings in Table 1, it can be known that the forgings have excellent hydrogen embrittlement resistance and low-temperature impact resistance.

[0073] It should be understood that in order to streamline the present disclosure and help understand one or more of the various inventive aspects, in the above description of the exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, the disclosed method should not be construed as reflecting the intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected by the claims, the inventive aspects lie in less than all of the features of the foregoing disclosed embodiments. Thus, the claims following the detailed description are hereby expressly incorporated into the detailed description, where each claim stands on its own as a separate embodiment of the present invention.

[0074] Although the present invention has been described based on a limited number of embodiments, those skilled in the art in this technical field will understand, based on the above description, that other embodiments can be conceived within the scope of the present invention thus described. In addition, it should be noted that the language used in this specification is mainly selected for the purpose of readability and teaching, rather than for the purpose of explaining or limiting the subject matter of the present invention. Therefore, many modifications and variations will be obvious to those of ordinary skill in the art without departing from the scope and spirit of the appended claims. For the scope of the present invention, the disclosure of the present invention is illustrative rather than restrictive, and the scope of the present invention is defined by the appended claims.

[0075] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for manufacturing an alloy steel slewing bearing forging having high strength and toughness and hydrogen embrittlement resistance, characterized in that: Including 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; The manufacturing method comprises the following steps: 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%~85%, the rolling speed is 0.5~1 m / s, and the final forging temperature of the first-stage ring rolling is not less than 1150℃; The deformation of the secondary ring rolling is controlled at 15%~25%, the rolling speed is 1.5~2 m / s, and the final forging temperature of the secondary ring rolling is controlled at 900℃~950℃; The interval between the first and second ring rolling is 120s~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 1.0-1.5 m / 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℃, kept warm for 10h~15h and then air-cooled; the second tempering temperature is 600℃~650℃, kept warm for 5h~8h and then air-cooled.

2. The manufacturing method according to claim 1, characterized in that: The outer ring diameter of the alloy steel support forging is 5~15m.

3. The alloy steel slewing bearing forging with high strength and toughness and hydrogen embrittlement resistance obtained by the manufacturing method according to claim 1 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.

4. The alloy steel slewing bearing forging with high strength and toughness and hydrogen embrittlement resistance according to claim 3 is characterized in that: Room temperature tensile strength ≥1050 MPa, yield strength ≥810 MPa, room temperature impact absorption energy greater than 135 A kv / J, -60 ℃ impact absorption energy greater than 35 A kv / J.

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

6. Application of the alloy steel slewing bearing forging with high strength and toughness and resistance to hydrogen embrittlement obtained by the manufacturing method of the alloy steel slewing bearing forging with high strength and toughness and resistance to hydrogen embrittlement according to claim 1 in ultra-high power wind turbines.

7. The use according to claim 6, characterized in that: The maximum power is >13MW.

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