Manufacturing process of high-power wind power gear pair part and product

Abstract

The invention discloses a manufacturing process of a high-power wind power gear pair part and a product, and belongs to the technical field of manufacturing of wind power gears. The technology comprises the steps of burdening, continuous casting, forging, punching, ring rolling and chambering and quenching and tempering heat treatment, in the step of ring rolling and chambering, radial pressure is controlled to be gradually increased and is withdrawn after the size of a blank is reached, the maximum radial pressure does not exceed 18 Mpa, and the radial pressure rate meets the condition that V1 is approximately equal to k1 (D / t) Mpa / s; the axial pressure is controlled to be gradually increased, the pressure is withdrawn after the blank size is reached, the maximum axial pressure does not exceed 15 Mpa, the axial pressure rate meets the condition that V2 is approximately equal to k2 (H / D) Mpa / s, and a blank is obtained through ring rolling and broaching; in the formula, D is the outer diameter of the blank, H is the height of the blank, t is the wall thickness of the blank, the unit is mm, k1 is the radial pressure rate empirical coefficient, k2 is the axial pressure rate empirical coefficient, and the unit is MPa / (s.mm).

Description

Technical Field

[0001] This invention belongs to the field of gear manufacturing technology, and more specifically, relates to a manufacturing process and product for a high-power wind turbine gear pair component. Background Technology

[0002] The wind power equipment manufacturing sector has seen rapid development in recent years. With the advancement of wind power technology, the trend towards higher power and higher efficiency in wind power equipment has become increasingly prominent. High-power wind turbine gear pairs are one of the key components of wind power equipment, especially for 20MW and above products. Their performance and quality directly affect the reliability and lifespan of the wind power equipment. Currently, the power output of onshore high-power wind power products is concentrated in the 6-8 MW range, suitable for high-wind-speed areas; offshore high-power wind power products with capacities of 12-16 MW have become mainstream, while those of 20 MW and above are entering the testing phase.

[0003] In existing technologies, high-power wind turbine gear components, including power transmission and main load-bearing components such as internal gear rings and external gear bushings, are typically manufactured using high-performance alloy steel ingots through a multi-fire forging process. Strict control of forging temperature and deformation rate is required during this process to ensure sufficient material ductility. For example, patent CN103990938A uses hollow punch forging to remove central defects in continuously cast billets. By limiting the forging dimensions, upsetting ratio, expansion ratio, and ring thickness, it provides qualified ring blanks to ensure the quality of large bearings and gear rings after rolling on a ring rolling mill. However, because gear rings, especially large-sized ones, generally have significant differences in inner and outer diameters, cracking can easily occur during the expansion process due to inconsistent stress magnitudes and deformation rates between the inner and outer rings. Therefore, there is an urgent need to propose a process that can prevent cracking in gear components. Summary of the Invention

[0004] 1. The problem to be solved To address the problem of cracking in existing high-power wind turbine gear components due to inconsistent stress magnitude and deformation rate between inner and outer rings, the primary objective of this invention is to provide a manufacturing process for high-power wind turbine gear components. A second objective of this invention is to provide high-power wind turbine gear pair parts manufactured using the above-described process.

[0005] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: The manufacturing process of the high-power wind turbine gear pair parts of the present invention includes the following steps: S1. Ingredients: The raw material composition by mass ratio includes: C: 0.38%-0.45%, Si: 0.17%-0.37%, Mn: 0.50%-0.80%, Ni: 0.50%-0.70%, Cr: 0.90%-1.20%, Mo: 0.15%-0.30%; Harmful element content: Sb≤0.001%, Bi≤0.005%, Sn≤0.005%, As≤0.005%, Pb≤0.001%, total content≤0.01%; N≤100ppm, H≤1.5ppm, O≤20ppm, Ca≤10ppm; S2. Continuous casting: BOF+LF+RH+CCM process is used to produce continuous casting billets. During the continuous casting process, the temperature is controlled at 1600~1700℃ to obtain continuous casting billets. a) BOF converter steelmaking: using molten iron containing the components of step S1 as raw material, high-pressure oxygen is introduced, and oxygen blowing is used for decarburization and dephosphorization for 15-20 minutes, controlling the dephosphorization rate to ≥95%; b) LF ladle refining: bottom blowing argon stirring, desulfurization and alloying, temperature precision control within ±5℃, processing time 30~60 minutes, sulfur content controlled ≤0.005%; c) RH vacuum circulation degassing: vacuum degree controlled ≤1mbar, circulation driven by argon, steel circulation rate is 80~120 tons / minute, processing time is 15~25 minutes, and the hydrogen content of the steel is controlled ≤1.0ppm and the oxygen content is controlled ≤15ppm. d) CCM continuous casting: The superheat is controlled at 15~30℃. The internal structure of the billet is improved by electromagnetic stirring. Argon gas is used for protection during the entire casting process to prevent secondary oxidation of the molten steel.

[0006] The low-magnification microstructure of the continuously cast billet produced by the above combined process meets the following requirements: central porosity ≤ 1.0 grade, shrinkage cavity ≤ 0.1 grade, central crack ≤ 0.1 grade, intermediate crack ≤ 0.5 grade, subcutaneous crack ≤ 0.1 grade, subcutaneous bubble ≤ 0.1 grade, and total defect amount ≤ 2.0 grade. The microstructure of the obtained continuously cast billet includes fine equiaxed crystal regions on the surface, columnar crystal regions, and central equiaxed crystal regions. The grain size of the continuously cast billet is 0~1 grade. Its metallographic structure contains more than 90% ferrite, and the remainder is a mixed structure of pearlite and bainite. S3. Forging: The first forging process compacts the continuously cast billet structure obtained in step S2 through upsetting and drawing with a press. The upsetting-drawing length ratio is ≥3, and the temperature is controlled at 1150-1200℃, which transforms the coarse columnar austenitic crystals into a uniform equiaxed grain structure. S4. Punching: Punching removes the loose area in the middle of the continuously cast billet and shapes it to meet the ratio of hole diameter to outer diameter of circle ≥1:4; S5. Ring rolling and hole expansion: The second rolling and hole expansion is carried out to the blank size to complete the blank forming and obtain the blank; During the ring rolling and hole enlargement process, the radial pressure and axial pressure are controlled, and the pressure is slowly applied at radial pressure rate V1 and axial pressure rate V2; this further refines the austenitic equiaxed grains. Specifically, the radial pressure satisfies the following: the radial pressure is gradually increased until it reaches the blank size, and then the pressure is slowly withdrawn. The maximum radial pressure does not exceed 18 MPa. The radial pressure rate satisfies: V1≈k1(D / t) MPa / s, where D is the outer diameter of the blank, t is the wall thickness of the blank (in mm), and k1 is the empirical coefficient of radial pressure rate (in MPa / (s·mm). The value of k1 ranges from 0.04 to 0.05, preferably 0.045. The axial pressure should meet the following requirements: the axial pressure should be gradually increased until it reaches the blank size, and then slowly withdrawn. The maximum axial pressure should not exceed 15 MPa. The axial pressure rate should meet the following requirement: V2≈k2(H / D) MPa / s, where H is the blank height, D is the blank outer diameter (in mm), and k2 is the empirical coefficient of axial pressure rate (in MPa / (s·mm). The value of k2 should be between 1.6 and 1.8, preferably 1.7.

[0007] Furthermore, during the ring rolling and reaming process, the radial pressure is controlled to be greater than the axial pressure. Preferably, the ratio of the radial pressure to the axial pressure is (1.2-1.5):1, and the above ratio is selected according to the weight of the billet and the size of the blank.

[0008] Furthermore, during the pressure control process, the upper limits of radial and axial pressure are adjusted according to the equipment capacity and the weight of the blank. The greater the weight of the blank, the larger the inner and outer diameters, and the greater the wall thickness, the higher the upper limit of pressure during the ring rolling and reaming process.

[0009] Furthermore, the hole expansion ratio is 1.1 to 2.2, preferably 1.8 to 2.2; The calculation of the hole expansion ratio Y is directly based on the wall thickness deformation: Y = T0 / T1. T0: Original wall thickness of the forging material before hole expansion; T1: Final wall thickness of the forging billet after hole expansion; This formula reflects the degree of deformation through the wall thickness reduction ratio, and its physical essence originates from the law of conservation of volume.

[0010] The microstructure of the blank obtained by ring rolling and hole expansion includes ≤10% ferrite, with the remainder being austenite.

[0011] S6. Quenching and tempering heat treatment: including quenching and tempering steps. The quenching process includes the following steps: heating to 400±10℃ at a rate of <300℃ / h and holding at that temperature for 4±0.5h; Heat to 650±10℃ at a rate of <300℃ / h and hold for 3±0.5h; Heat to 850±10℃ at a rate of <200℃ / h and hold for 5±0.5h; Cool the solvent for 15-18 minutes, alternating between air and liquid; The tempering process includes the following steps: heating to 400±10℃ at a rate of <300℃ / h and holding for 4±0.5h; Heat to 590±10℃ at a rate of <300℃ / h and hold for 6±0.5h; The gear pair parts of this application are obtained by air cooling to room temperature.

[0012] Furthermore, the gear pair parts of the present invention are relatively large in size, especially those with an inner diameter of 800-1900mm, an outer diameter of 1500-2200mm, and an inner-outer diameter ratio of 0.36-0.90. These parts are prone to uneven local temperature and large deformation differences. Therefore, it is necessary to control the heating rate to ensure uniform heating of the product and control uniform deformation.

[0013] The final metallographic structure of the gear pair part consists of ≥95% sorbite and ≤5% bainite, with a grain size of ≥7.

[0014] After quenching and tempering heat treatment, the tensile strength R of the gear pair parts m ≥1000MPa, yield strength Rp 0.2 ≥800Mpa, elongation after fracture A≥14%, reduction of area Z≥50%, impact absorption energy≥110KU2 / J, meeting the requirements of gear pairs for high-power 20MW and above wind turbines.

[0015] 3. Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: I. Manufacturing Process: (1) This invention adjusts the radial and axial pressures during the ring rolling and reaming process to ensure uniform microstructure on both the inner and outer sides of the ring, resulting in a final product with a tensile strength R at room temperature. m ≥1000MPa, yield strength Rp 0.2 ≥800Mpa, elongation after fracture A≥14%, reduction of area Z≥50%, impact absorption energy≥110KU2 / J, meeting the requirements of gear pair parts for high-power 20MW and above wind turbines; (2) The present invention adjusts the composition and process, on the one hand, by forming a structure with higher grain size, generating a denser structure, and on the other hand, by controlling the rolling and expanding process, thereby controlling the distribution of tensile stress on the surface of the product, reducing the structural stress generated by the structural transformation during the quenching process, thereby effectively reducing the quenching and tempering deformation, and finally the dimensional change of the internal gear ring before and after quenching and tempering is within 2 mm. (3) By optimizing the alloy material, the optimized continuous casting billet ordinary alloy material has a lower cost than commonly used high performance alloy materials and a high material utilization rate, thereby reducing the manufacturing cost of high power wind turbine gear pairs. II. Gear Pair Components (4) The room temperature performance of the gear pair parts of the present invention is the tensile strength R m ≥1000MPa, yield strength Rp 0.2 ≥800Mpa, elongation after fracture A≥14%, reduction of area Z≥50%, impact absorption energy≥110KU2 / J, meeting the requirements of gear pair parts for high-power 20MW and above wind turbines; (5) The dimensional change of the gear pair parts of the present invention before and after heat treatment is within 2 mm. Attached Figure Description

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless specifically indicated, these drawings are intended only to conceptually illustrate the structural construction described herein and are not necessarily drawn to scale.

[0017] Figure 1 The low-magnification microstructure of the continuously cast billet obtained in Example 1; Figure 2 The tensile property curve of the internal gear ring obtained in Example 1 is as follows: Figure 3 The image shows the grain morphology of the internal gear ring prepared in Example 1. Figure 4 The heating curve for tempering and quenching in Example 1; Figure 5 The heating curve for tempering and quenching in Example 1; Figure 6 This is a distribution diagram of the continuously cast billet in Example 1. In the diagram, A is the surface fine-grained region; B is the columnar crystal region; and C is the central equiaxed crystal region. Figure 7 This is a simulated particle size distribution diagram of the internal gear ring prepared in Example 1; Figure 8 The diagram shows the equivalent stress distribution of the internal gear ring prepared in Example 1. Detailed Implementation

[0018] The following detailed description of exemplary embodiments of the invention is taken with reference to the accompanying drawings, which form part of the description and illustrate exemplary embodiments in which the invention may be practiced. While these exemplary embodiments have been described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be implemented and various changes may be made to the invention without departing from the spirit and scope thereof. The more detailed description of embodiments of the invention below is not intended to limit the scope of the claimed invention, but is merely illustrative and not restrictive of the description of the features and characteristics of the invention, to suggest the best mode for carrying out the invention, and is sufficient to enable those skilled in the art to practice the invention. Therefore, the scope of the invention is defined only by the appended claims.

[0019] In this application, "continuous casting billet" refers to the billet obtained after the continuous casting process; In this application, "forging billet" refers to the billet obtained after a press forging process; In this application, "blank" refers to the blank obtained after the ring rolling and reaming step. The radial pressure rate V1 is calculated based on the dimensions of the blank, i.e., the blank obtained after the ring rolling and reaming step.

[0020] This application describes the manufacturing process of high-power wind turbine gear pair parts, which include an internal gear ring and an external gear bushing. Considering the inconsistency in stress magnitude and deformation rate between the inner and outer rings during the ring rolling and reaming process, which can lead to cracking, this application achieves uniformity in the reaming process of the gear pair products through the combination of components and processes.

[0021] This method is applicable to the machining of ring-shaped parts with inner and outer diameters, such as internal gear rings and external gear bushings, with an inner diameter of 800-1900 mm, an outer diameter of 1500-2200 mm, and an inner-outer diameter ratio of 0.36-0.90.

[0022]

Ingredients

[0023] This steel grade achieves a balance between high strength and toughness through medium carbon alloying and multi-element alloying (Cr-Ni-Mo). Strict control of harmful elements ensures process stability, and the elements work synergistically. Medium carbon materials with a C content of 0.38%-0.45% are selected to balance strength and toughness. Si has a strong affinity for O, forming SiO2, which preferentially reduces the oxygen activity in the molten pool, creating a low-oxygen environment for Mn desulfurization. Mn combines with S to form MnS, replacing FeS. MnS has a high melting point (1610℃) and good plasticity, avoiding hot brittleness. Si indirectly promotes MnS precipitation by reducing the sulfur activity coefficient. The combined effect of Mn-Si optimizes deoxidation, desulfurization, and solid solution strengthening, while the combined effect of Cr-Mo-Ni improves hardenability, high-temperature performance, and corrosion resistance. This composition design is suitable for high-strength gears, bearings, heavy-duty shafts, and other products requiring a balance of high strength, wear resistance, and toughness.

[0024] It should be noted that because the forging blank of this component has higher strength, it is more prone to cracking during the hole expansion process. Therefore, it is necessary to control the axial and radial pressure and rate to avoid cracking of the blank during the ring rolling hole expansion process.

[0025]

Circuit Rolling and Hole Reaming Process Parameters

[0026] The axial pressure is controlled to increase gradually until it reaches the blank size, after which the pressure is slowly withdrawn. The maximum axial pressure does not exceed 15 MPa. The axial pressure rate satisfies: V2≈k2(H / D) MPa / s, where H is the blank height, D is the blank outer diameter (in mm), and k2 is the empirical coefficient of axial pressure rate (in MPa / (s·mm). The value of k2 is in the range of 1.6-1.8, preferably 1.7.

[0027] In the ring rolling and reaming process, an empirical formula is used to control the pressure application rate. Its core principle is to dynamically adjust the pressure application rate based on the blank dimensions, i.e., the diameter-to-thickness ratio (D / t) and height-to-diameter ratio (H / D), to balance material deformation uniformity and process efficiency. When the ratio is large, the material deformation resistance is high, requiring a higher pressure application rate to overcome this resistance. However, the rate should not be too high, otherwise it may lead to cracks and internal defects. The empirical coefficient is set as a safe value determined through experiments. This empirical formula is somewhat dependent on the material and temperature, and the empirical coefficient needs to be adjusted according to specific circumstances.

[0028] It is important to note that in the ring rolling and reaming process, the radial direction is the reaming direction, requiring rapid radial forming to reduce energy consumption and time, while ensuring precise axial control to guarantee dimensional accuracy and internal quality. Therefore, the radial pressure should be greater than the axial pressure. Preferably, the ratio of the radial pressure to the axial pressure is (1.2-1.5), and this ratio is selected based on the weight of the blank and the blank size.

[0029] The upper limit of the pressure is to prevent the material from undergoing plastic instability under high pressure. This upper limit is adjusted according to the capacity of the equipment (the present invention uses a ring rolling mill) and the weight of the blank. Specifically, as shown in Table 1, when the blank weight is 1-5t and the finished product size is Φ500-1000mm, the upper limit of the radial pressure is 15MPa and the upper limit of the axial pressure is 10MPa; when the blank weight is 5-12t and the finished product size is Φ1000-2000mm, the upper limit of the radial pressure is 18MPa and the upper limit of the axial pressure is 15MPa.

[0030] Table 1 Selection of parameters for ring rolling mill

[0031] It is important to note that due to the addition of multi-element alloys, the strength is higher, requiring greater pressure during ring rolling and cavitation. However, excessive pressure and rapid pressurization can increase the stress difference between the inner and outer rings, further leading to surface cracking. Therefore, the axial and radial pressure and rate need to be adjusted in conjunction with the composition and process. The material composition, through solid solution strengthening and carbide precipitation, determines the high-temperature dynamic yield strength, directly affecting the upper limit of pressure. For example, Cr can improve creep resistance, increasing the yield strength σ. yIt maintains a strength ≥450 MPa at 950℃, supporting a radial pressure threshold of 18 MPa. Mo can suppress dynamic recrystallization and reduce the material's strain rate sensitivity. When the axial pressure rate >0.5 MPa / s, composition optimization (e.g., adjusting the Mo content to 0.15%–0.25%) is necessary to avoid cracks caused by localized hardening. The added Ni, Cr, and Mo form a synergistic effect, further ensuring the smooth implementation of ring forging. Ni's d electrons form hybrid orbitals with Cr / Mo, enhancing the covalent bond strength of the passivation film; Ni widens the austenite region, while Cr and Mo regulate the type and distribution of carbides; Ni improves toughness, and C and Mo provide composite strengthening.

[0032] Radial pressure rate V1 The derivation of radial pressure rate (V1) is based on the material flow equation: According to the theory of plastic deformation of ring expansion, the radial pressure rate must satisfy the coordination of material flow.

[0033] The radial deformation rate (V1) is directly related to the ratio of the blank's outer diameter (D) and wall thickness (t). Combining process test data, an empirical coefficient k1 is introduced, and the final result is: V1 = k1·D / t (MPa / s). In the formula, k1 is the empirical coefficient of radial pressure rate, with the unit being MPa / (s·mm), D is the outer diameter of the blank, and t is the wall thickness of the blank, with the unit being mm. Both the outer diameter of the blank D and the wall thickness of the blank t are the dimensions of the blank obtained after the ring rolling and reaming.

[0034] The empirical coefficient k1 is determined based on experimental verification and material properties: Experimental Verification: Through multiple sets of D / t ratio experiments, the forming quality (such as surface cracks and dimensional accuracy) of the products under different k1 values ​​was observed. For example, when D / t=100, if k1=0.04, then V1=4 MPa / s; if k1=0.05, then V1=5 MPa / s. The experimental results show that the efficiency is too low when k1<0.04, and surface defects are prone to occur when k1>0.05.

[0035] Material property adaptation: For materials commonly used in wind turbine gears (such as 18CrNiMo7-6 steel), their high-temperature plastic deformation characteristics require the pressure rate to match the material's rheological behavior. This material has a low strain rate sensitivity coefficient at 950~1050℃, and the pressure rate needs to be adjusted via k1 to avoid localized overheating or overload.

[0036] Based on the experimental data and material properties, k1∈[0.04,0.05] was finally determined to balance efficiency and quality.

[0037] Axial pressure rate V2 The derivation of the axial compressive rate (V2) is based on the principle of constant volume: axial deformation must satisfy the volume conservation condition of plastic deformation. The radial deformation rate (V2) is directly related to the ratio of the blank height (H) to the ring outer diameter (D). The axial deformation rate needs to match the ring height-to-diameter ratio to prevent uneven or out-of-round end faces. Introducing the empirical coefficient k2, we get: V2 = k2·H / D (MPa / s) Determination of the empirical coefficient k2: Experimental verification and process adaptability: Experimental Verification: The effect of k2 on forming was tested for rings with different H / D ratios (e.g., H / D = 0.5~1.5). For example, when H / D = 1, if k2 = 1.6, then V2 = 1.6 MPa / s; if k2 = 1.8, then V2 = 1.8 MPa / s. The experiment showed that when k2 < 1.6, axial filling was insufficient, and when k2 > 1.8, end face folding was likely to occur.

[0038] Process adaptability: During ring rolling and reaming, axial pressure needs to work in conjunction with radial pressure. Since radial pressure > axial pressure, k2 must ensure that the axial deformation rate does not interfere with the principal radial deformation to avoid material flow turbulence.

[0039] Based on the combined experimental results and process coordination requirements, k2∈[1.6,1.8] was determined to optimize the axial forming uniformity.

[0040] [Product Organization and Performance] The low-magnification microstructure of the continuously cast billet produced in step S2 meets the following requirements: central porosity ≤ 1.0 grade, shrinkage cavity ≤ 0.1 grade, central crack ≤ 0.1 grade, intermediate crack ≤ 0.5 grade, subcutaneous crack ≤ 0.1 grade, subcutaneous bubble ≤ 0.1 grade, and total defect amount ≤ 2.0 grade. The microstructure of the obtained continuously cast billet includes fine equiaxed crystal regions on the surface, columnar crystal regions, and central equiaxed crystal regions, with strong directionality, such as... Figure 6 As shown, the continuously cast billet, from the outside to the inside, includes a fine-grained region (A), a columnar grain region (B), and an equiaxed grain region (C). These regions exhibit strong directionality and poor uniformity, making them prone to cracking during the ring rolling and reaming deformation process. The billet also has coarse grains (0-1 grade) and uneven microstructure distribution. Using conventional ring rolling and reaming processes easily leads to inconsistencies in the stress magnitude and deformation rate between the inner and outer rings, resulting in a high susceptibility to cracking.

[0041] This application eliminates columnar grain regions and destroys original grain boundaries by controlling the process parameters of forging and ring rolling, thereby reducing the risk of anisotropy. On the one hand, the heat treatment state is maintained during the process, causing most of the ferrite in the microstructure of the blank formed by forging and ring rolling to transform into austenite, improving the structural strength. On the other hand, the forging and ring rolling processes refine the microstructure grains, reducing the austenite grain size from grade 0-1 to grade ≥7, thus improving the mechanical properties of the product. Through high-temperature heating and external force to break the grains, the grains re-nucleate during the breaking process, homogenizing the microstructure of different grain regions and eliminating anisotropy in mechanical properties. Further, through quenching and tempering, the resulting gear pair parts meet the requirements of hardness HB280-320 and tensile strength R... m ≥1000MPa, yield strength Rp 0.2 With a bearing capacity of ≥800 MPa, elongation after fracture A≥14%, reduction of area Z≥50%, and impact absorption energy ≥110 KU2 / J, it can withstand the performance requirements of 28500 KN load under heavy-duty workpieces, meeting the needs of gear pairs for high-power 20MW and above wind turbines.

[0042] It should be noted that the product exhibits different structural compositions within different temperature ranges of continuous casting, forging, ring rolling and hole expansion, and quenching and tempering. When the part temperature is between 850 and 1240°C, the continuously cast billet is composed of austenitic columnar crystals. During the billet upsetting and drawing process, the coarse austenitic columnar crystals are transformed into a uniform equiaxed grain structure. After the ring rolling and hole expansion step, the austenitic equiaxed grains are further refined. After quenching and tempering heat treatment, the final product contains ≥95% sorbite and ≤5% bainite, with the austenite grain size refined from grade 0 to 1 to grade ≥7.

[0043] Tempering heat treatment The quenching and tempering heat treatment process includes quenching and tempering steps: Among them, the quenching process is as follows Figure 4 As shown, the temperature was increased to 400±10℃ at a rate of <300℃ / h and then held for 4±0.5h. Heat to 650±10℃ at a rate of <300℃ / h and hold for 3±0.5h; Heat to 850±10℃ at a rate of <200℃ / h and hold for 5±0.5h; PAG was cooled for 15-18 minutes, with alternating air and liquid phases, and the dimensional changes before and after conditioning were recorded.

[0044] The tempering process is as follows Figure 5 As shown, the temperature was increased to 400±10℃ at a rate of <300℃ / h and held for 4±0.5h. Heat to 590±10℃ at a rate of <300℃ / h and hold for 6±0.5h; Air cool to room temperature.

[0045] Tempering heat treatment is used to obtain excellent comprehensive mechanical properties of materials. However, excessively high austenitizing temperatures, quenching cooling rates, and quenching hardness can lead to uneven distribution of structural and thermal stress during the heat treatment process, resulting in deformation or even cracking of the gear ring. The final product will have a sorbite content ≥95% and bainite ≤5%. It should be noted that hardness is generally inversely proportional to plasticity; higher hardness generally results in poorer plasticity, making the workpiece more prone to cracking.

[0046] The final gear pair parts have a dimensional change of less than 2mm before and after heat treatment.

[0047] In summary, the factors affecting workpiece deformation during quenching and tempering heat treatment include microstructure and composition. A uniform forging microstructure and chemical composition can effectively reduce the structural stress generated during the microstructure transformation in the quenching process, thus preventing deformation. During ring rolling and hole expansion, ferrite transforms into austenite, resulting in a volume change. For a given mass of iron, during the transformation from ferrite (α-Fe) to austenite (γ-Fe), the difference in atomic density (γ-Fe has a density of 74%, while α-Fe has a density of 68%) leads to a volume reduction during the transformation. This makes it prone to cracking after sintering. Combined with the stretching of the inner and outer diameters during hole expansion, tensile stress is generated on the surface, making the surface of gear parts prone to cracking. Similarly, during the transformation from austenite to tempered sorbite, austenite has a higher density (γ-Fe has a density of 74% and a denser atomic arrangement), while tempered sorbite, with its ferrite matrix, has a lower density (α-Fe). The density is 68%. Furthermore, carbon exists in the austenite as interstitial solid solution, causing slight lattice expansion. When austenite transforms into tempered sorbite, carbon precipitates from the solid solution, forming fine granular carbides (such as Fe3C). Under the combined effect of the crystal structure inversion and carbon precipitation, the volume expands, typically by 1% to 3%. Therefore, under temperature changes or heavy loads, different transformations in the metallographic structure lead to deeper cracks in gear components, and even fracture, posing a significant risk.

[0048] Surprisingly, the adjustments to composition and process in the above-mentioned ring rolling and hole expansion process can simultaneously address the issue of dimensional changes in gear pair parts before and after tempering. To ensure the structural strength of the gear pair parts, the final gear pair parts product needs to have a high content of tempered sorbite. Tempered sorbite is generally transformed from austenite through heat treatment, and austenite is generally transformed from ferrite through high-temperature treatment. During this transformation of metallographic composition, due to the difference in density, cracks will occur in the tempered gear pair parts. Therefore, this application addresses this issue by forming a higher grain size structure, refining the final austenite grain size from level 0-1 to ≥7. A higher grain size structure is more likely to generate a denser structure, filling the volume voids and reducing the volume shrinkage / expansion rate. On the other hand, by controlling the ring rolling and hole expansion process, the distribution of tensile stress on the product surface is controlled, and the structural stress generated by the structural transformation during the quenching process can effectively reduce tempering deformation. The overall residual stress is mostly around 15 MPa, and the stress in the area in contact with the inner and outer rolls reaches about 40 MPa, thus avoiding the risk of defects such as cracks caused by local stress concentration.

[0049] Most of the grains in the core of the product are refined to below 17.0μm, and the grains on the inner and outer surfaces are refined to about 8.0μm. The grain size level meets the austenitic grain size requirement of ≥7 grade for integral forging, in accordance with GB / T 6394-2017 standard.

[0050] [Testing Method] The mechanical properties of this application, including tensile strength, yield strength, elongation after fracture, reduction of area, and impact energy, are determined according to GB / T228.1-2021 Metallic Materials - Tensile Testing - Part 1: Room Temperature Test Method and GB / T229-2020 Metallic Materials - Charpy Pendulum Impact Test Method. Hardness was determined according to Part 1 of GB / T 231.1-2018 Metallic Materials Brinell Hardness Test. Grain size was determined according to GB / T 6394-2017 "Method for Determination of Average Grain Size of Metals"; The low-magnification microstructure of the continuously cast billet was determined according to GB / T 226-2015 "Acid Etching Test Method for Low-Magnification Microstructure and Defects of Steel" and YB / T153 "Rating Chart of Low-Magnification Microstructure Defects of Continuously Cast Square Billets of High-Quality Carbon Structural Steel and Alloy Structural Steel". The stress distribution was determined according to ASTM E837: Standard test method for measuring residual stress by drilling (strain gauge) and GB / T 7704: Determination of residual stress on the surface of metallic materials by X-ray diffraction. The stress distribution simulation process: All molds were defined as isothermal rigid bodies, and the workpiece was meshed using a hexahedral mesh with a mesh size of 15 mm. Adaptive mesh re-meshing technology was used to simulate the large deformation process of the workpiece. During the upsetting and drawing processes, the hydraulic press adopted a constant rate control mode with a pressing rate of 50 mm / s. The contact type between the billet and the mold was defined as a Coulomb friction model. The main parameters of the ring forming process are shown in Table 1. Table 1. Main parameters for simulation of the ring forming process.

[0051] Example 1 This embodiment discloses the manufacturing process of the internal gear ring of a high-power wind turbine gear pair. In this embodiment, the size of the continuously cast billet is φ800×1250mm. The specific steps are as follows: Step S1, Batching: Prepare alloy steel material with the following chemical composition by mass fraction: C: 0.45%, Si: 0.37%, Mn: 0.80%, P: ≤0.025%, S: ≤0.020%, Cr: 0.90%, Mo: 0.15%, Ni: 0.70%. The optimized proportions of the above chemical composition ensure the excellent mechanical properties of the material. S2, Continuous Casting: Smelting using BOF+LF+RH+CCM process: a) BOF converter steelmaking: oxygen blowing for decarburization and dephosphorization for 15 minutes, introducing high-pressure (1.2Mpa) oxygen with a purity ≥99.5%, temperature controlled at 1600℃, dephosphorization rate 95%; b) LF ladle refining: bottom blowing argon stirring, desulfurization and alloying, processing time is 30 minutes, sulfur content ≤0.005%, temperature precision control ±5℃; c) RH vacuum circulation degassing: The vacuum degree is controlled at 1 mbar, and the molten steel is circulated at 80 tons / minute by argon gas. The processing time is 15 minutes, and the hydrogen content and oxygen content of the molten steel are controlled to be ≤1.0 ppm and ≤15 ppm respectively. d) CCM continuous casting: The superheat is controlled at 15℃ to prevent cracks and center segregation. Electromagnetic stirring is used to improve the uniformity of the internal structure of the billet. Argon gas is used for protection during the entire casting process to prevent secondary oxidation of the molten steel.

[0052] A φ800×1250mm continuous casting billet was produced. The low-magnification microstructure of the billet met the following requirements: central porosity ≤ 1.0 grade, shrinkage cavity ≤ 0.1 grade, central crack ≤ 0.1 grade, intermediate crack ≤ 0.5 grade, subcutaneous crack ≤ 0.1 grade, subcutaneous bubble ≤ 0.1 grade, and total defect amount ≤ 2.0 grade. The continuous casting billet, by mass percentage, consists of 15% surface fine grain region A, 70% columnar grain region B, and 15% intermediate equiaxed grain region C from the outside in. It has strong directionality and poor uniformity, and is prone to cracking during the deformation process of ring rolling and hole expansion. These strict microstructure requirements ensure the high quality of the continuous casting billet and lay a solid foundation for subsequent forging.

[0053] S3. Forging: The first hot press is used for upsetting and drawing forging at a pressure of 80000KN. The continuously cast billet material obtained in step S2 is heated to 1200℃ and held for 60 minutes. Then, upsetting and drawing forging is carried out with an upsetting-to-drawing length ratio of ≥3. Finally, the material reaches a size of φ1100×640mm. The uniformity of the material structure after upsetting and drawing forging is improved.

[0054] S4. Punching: Punch holes of φ580 and shape them to φ1200×φ580×640mm to remove the loose areas in the middle of the material and further increase the density of the material.

[0055] S5. Ring Rolling and Hole Enlargement: The material after punching and shaping in step S4 is heated to 950℃ and held for 80 minutes. Then, ring rolling and hole enlargement is performed to achieve the final size of φ2052×φ1756×606mm. During the ring rolling and hole enlargement process, the radial pressure is controlled to not exceed 18Mpa, and the radial pressure rate is increased at 0.62Mpa / s. The axial pressure is controlled to not exceed 15Mpa, and the axial pressure rate is increased at 0.50Mpa / s. After reaching the blank size, the pressure is slowly withdrawn. This process fully breaks up the dendritic structure inside the material, making the material structure uniform. The metallographic structure of the blank includes ≤5% ferrite, and the rest is austenite with a grain size of ≥8. The calculation of radial pressure velocities V1 and V2 is based on the final dimensions φ2052×φ1756×606mm, and the calculation steps are as follows: V1≈k1(D / t) Mpa / s, where D is the outer diameter of the blank, which is 2052mm, t is the wall thickness of the blank, which is (2052-1756) / 2=148mm, and k1 is 0.045. The calculated radial pressure rate V1 is 0.62 Mpa / s. V2≈k2(H / D) Mpa / s, where H is the blank height, which is 606 mm, D is the blank outer diameter, which is 2052 mm, and k2 is 1.7. The calculated axial pressure rate V2 is 0.50 Mpa / s. S6. Quenching and tempering: The quenching and tempering process includes quenching and tempering steps. Among them, the quenching process is as follows Figure 4 As shown, the temperature was increased to 400℃ at a rate of 280℃ / h and then held for 4 hours. Heat to 650℃ at a rate of 280℃ / h and hold for 3 hours; Heat to 850℃ at a rate of 180℃ / h and hold for 5 hours; PAG was cooled for 15-18 minutes, with alternating air and liquid phases, and the dimensional changes before and after conditioning were recorded.

[0056] The tempering process is as follows Figure 5 As shown, the temperature was increased to 400℃ at a rate of 280℃ / h and held for 4 hours; Heat to 595℃ at a rate of 280℃ / h and hold for 6 hours; Air cool to room temperature.

[0057] After quenching and tempering, the microstructure consists of ≤5% bainite, with the remainder being tempered sorbite with a grain size of ≥8.

[0058] The product obtained meets the performance requirements of tensile strength greater than 1000 MPa and impact absorption energy greater than 110 KU2 / J. It can not only improve the performance and reliability of the internal gear ring of high-power wind turbine gear pair, but also effectively shorten the production process, reduce production costs, and achieve the goal of green manufacturing. Its performance is shown in Table 2.

[0059] Furthermore, through reasonable adjustments to the composition and process, Ni inhibits austenite grain growth, resulting in a more uniform microstructure after tempering, reducing deformation caused by localized stress concentration, and increasing austenite stability. Therefore, the tempering time needs to be extended (≥2h) to fully decompose residual austenite and avoid subsequent dimensional springback. The dimensional changes of the resulting internal gear ring before and after tempering are within 2mm, meeting the standard requirements. The dimensions of the tempered internal gear ring products are shown in Table 3.

[0060] The grain size distribution is as follows Figure 7 As shown, the stress distribution is as follows Figure 8 As shown, most of the grains in the core of the final product are refined to below 17.0 μm, and the grains on the inner and outer surfaces are refined to about 8.0 μm. The grain size level is in accordance with the GB / T6394-2017 standard, with austenitic grain size ≥ 7. The equivalent stress distribution shows that the overall residual stress is mostly around 15 MPa, and the stress in the part of the contact area with the inner and outer rolls reaches about 40 MPa. There is no risk of defects such as cracks caused by local stress concentration.

[0061] Example 2 This embodiment discloses the manufacturing process of the external gear bushing of a high-power wind turbine gear pair. In this embodiment, the size of the continuously cast billet is φ900×2000mm. The specific steps are as follows: S1. Ingredients: Prepare alloy steel material with the following chemical composition by mass fraction: C: 0.38%, Si: 0.17%, Mn: 0.50%, P: ≤0.025%, S: ≤0.020%, Cr: 1.20%, Mo: 0.30%, Ni: 0.50%. The optimized proportion of the above chemical composition ensures the excellent mechanical properties of the material. S2, Continuous casting: BOF+LF+RH+CCM process smelting; a) BOF converter steelmaking: oxygen blowing for decarburization and dephosphorization for 20 minutes, high-pressure oxygen (purity ≥99.5%) is introduced, the temperature is controlled at 1700℃, and the dephosphorization rate is 96%; b) LF ladle refining: desulfurization and alloying, processing time is 60 minutes, sulfur content ≤0.005%, temperature precision control ±5℃; c) RH vacuum circulation degassing: The vacuum degree is controlled at 0.8 mbar, and the molten steel is circulated at 120 tons / minute driven by argon gas. The processing time is 25 minutes, and the hydrogen content of the molten steel is controlled at ≤1.0 ppm and the oxygen content is controlled at ≤15 ppm. d) CCM continuous casting: The superheat is controlled at 30℃ to prevent cracks and central segregation. Electromagnetic stirring is used to improve the uniformity of the internal structure of the billet. Argon gas is used for protection during the entire casting process to prevent secondary oxidation of the molten steel.

[0062] A φ800×1250mm continuous casting billet was produced. The low-magnification microstructure of the billet met the following requirements: central porosity ≤ 1.0 grade, shrinkage cavity ≤ 0.1 grade, central crack ≤ 0.1 grade, intermediate crack ≤ 0.5 grade, subcutaneous crack ≤ 0.1 grade, subcutaneous bubble ≤ 0.1 grade, and total defect amount ≤ 2.0 grade. These strict microstructure requirements ensured the high quality of the continuous casting billet and laid a solid foundation for subsequent forging.

[0063] S3. Forging: The first heat-pressed forging is carried out at a pressure of 80,000 KN. The new continuous casting billet material is heated to 1150℃ and held for 120 minutes, and then upset forging is carried out. The upset-drawing length ratio is ≥3, and the final size is φ1400×800mm. The uniformity of the material structure is improved after upset forging.

[0064] S4. Punching: Punch φ580 holes and shape them to φ1500×φ580×750mm to remove the loose areas in the middle of the material and further increase the density of the material. S5. Ring Rolling and Hole Enlargement: The material after punching and shaping in step S4 is heated to 1000℃ and held for 50 minutes. Then, ring rolling and hole enlargement are performed to achieve the final dimensions of φ1899×φ1126×611mm. During the ring rolling and hole enlargement process, the radial pressure is controlled to not exceed 18MPa, and the radial pressure rate is increased at 0.25MPa / s. The axial pressure is controlled to not exceed 15MPa, and the axial pressure rate is increased at 0.55MPa / s. After reaching the blank size, the pressure is slowly withdrawn. This process fully breaks down the dendritic structure inside the material, resulting in a uniform material structure. This method is simple and efficient, removing the unique intermediate loose zone of the continuously cast billet, improving the performance and reliability of the product. The metallographic structure of the obtained billet includes ≤5% ferrite, with the remainder being austenite, and its grain size is grade 8. The calculation of radial pressure velocities V1 and V2 is based on the final dimensions φ1899×φ1126×611mm, and the calculation steps are as follows: V1≈k1(D / t) Mpa / s, where D is the outer diameter of the blank, which is 1899 mm, t is the wall thickness of the blank, which is (1899-1126) / 2=386.5 mm, and k1 is 0.05. The calculated radial pressure rate V1 is 0.25 Mpa / s. V2≈k2(H / D) Mpa / s, where H is the blank height, which is 611 mm, D is the blank outer diameter, which is 1899 mm, and k2 is 1.7. The calculated axial pressure rate V2 is 0.5 Mpa / s. S6. Quenching and tempering: The quenching and tempering process includes quenching and tempering steps. Among them, the quenching process is as follows Figure 4 As shown, the temperature was increased to 400℃ at a rate of 280℃ / h and then held for 4 hours. Heat to 650℃ at a rate of 280℃ / h and hold for 3 hours; Heat to 850℃ at a rate of 180℃ / h and hold for 5 hours; PAG was cooled for 15-18 minutes, with alternating air and liquid phases, and the dimensional changes before and after conditioning were recorded.

[0065] The tempering process is as follows Figure 5 As shown, the temperature was increased to 400℃ at a rate of 280℃ / h and held for 4 hours; Heat to 595℃ at a rate of 280℃ / h and hold for 6 hours; Air cool to room temperature.

[0066] After quenching and tempering, the microstructure consists of ≤5% bainite, with the remainder being tempered sorbite with a grain size of ≥8.

[0067] The product obtained meets the performance requirements of tensile strength greater than 1000 MPa and impact absorption energy greater than 110 KU2 / J. It can not only improve the performance and reliability of high-power wind turbine gear pairs, but also effectively shorten the production process, reduce production costs, and achieve the goal of green manufacturing. The performance of the obtained product is shown in Table 2.

[0068] Furthermore, through reasonable adjustments to the composition and process, Ni inhibits austenite grain growth, resulting in a more uniform microstructure after tempering and reducing deformation caused by localized stress concentration. It also increases austenite stability, requiring an extended tempering time (≥2h) to fully decompose residual austenite and prevent subsequent dimensional springback. This ensures that the dimensional change of the resulting external gear bushing before and after tempering is within 2mm, meeting standard requirements. The dimensions of the tempered external gear bushing are shown in Table 3.

[0069] Table 2 Performance Data Table for Examples 1-2

[0070] Table 3. Dimensions of blanks and products before and after tempering in Examples 1-2

[0071] Example 3 This embodiment discloses a manufacturing process for the internal gear ring of a high-power wind turbine gear pair, which differs from Embodiment 1 in that... In step S5, the final dimensions of the blank are φ2052×φ1756×606mm. The radial pressure is controlled to not exceed 18 MPa, and is gradually increased at a rate of 0.55 MPa / s. The axial pressure is controlled to not exceed 15 MPa, and is gradually increased at a rate of 0.53 MPa / s. After reaching the blank size, the pressure is simultaneously and slowly withdrawn. This process ensures thorough breakup of the dendritic structure within the material, resulting in a uniform material microstructure. The resulting blank exhibits a metallographic structure comprising ≤5% ferrite, with the remainder being austenite, and a grain size ≥8.

[0072] The calculation of radial pressure velocities V1 and V2 is based on the final dimensions φ2052×φ1756×606mm, and the calculation steps are as follows: V1≈k1(D / t) Mpa / s, where D is the outer diameter of the blank, which is 2052mm, t is the wall thickness of the blank, which is (2052-1756) / 2=148mm, and k1 is 0.04. The calculated radial pressure rate V1 is 0.55 Mpa / s. V2≈k2(H / D) Mpa / s, where H is the blank height, which is 606 mm, D is the blank outer diameter, which is 2052 mm, and k2 is 1.8. The calculated axial pressure rate V2 is 0.53 Mpa / s. The product obtained meets the performance requirements of tensile strength greater than 1000 MPa and impact absorption energy greater than 110 KU2 / J. It can not only improve the performance and reliability of the internal gear ring of high-power wind turbine gear pairs, but also effectively shorten the production process, reduce production costs, and achieve the goal of green manufacturing.

[0073] In addition, the dimensional change of the internal gear ring before and after heat treatment is within 2mm, which meets the standard requirements.

[0074] Example 4 This embodiment discloses a manufacturing process for the external gear bushing of a high-power wind turbine gear pair, which differs from Embodiment 2 in that... In step S5, the final dimensions of the blank are φ1899×φ1126×611mm. The radial pressure is controlled to not exceed 18 MPa, and is gradually increased at a rate of 0.55 MPa / s. The axial pressure is controlled to not exceed 15 MPa, and is gradually increased at a rate of 0.53 MPa / s. After reaching the blank size, the pressure is simultaneously and slowly withdrawn. This process ensures thorough breakup of the dendritic structure within the material, resulting in a uniform material microstructure. The resulting blank exhibits a metallographic structure comprising ≤5% ferrite, with the remainder being austenite, and a grain size ≥8.

[0075] The calculation of radial pressure velocities V1 and V2 is based on the final dimensions φ1899×φ1126×611mm, and the calculation steps are as follows: V1≈k1(D / t) Mpa / s, where D is the outer diameter of the blank, which is 1899 mm, t is the wall thickness of the blank, which is (1899-1126) / 2=386.5 mm, and k1 is 0.045. The calculated radial pressure rate V1 is 0.22 Mpa / s. V2≈k2(H / D) Mpa / s, where H is the blank height, which is 611 mm, D is the blank outer diameter, which is 1899 mm, and k2 is 1.6. The calculated axial pressure rate V2 is 0.51 Mpa / s. The product meets the performance requirements of tensile strength greater than 1000 MPa and impact absorption energy greater than 110 KU2 / J. It can not only improve the performance and reliability of the external gear bushing of high-power wind turbine gear pairs, but also effectively shorten the production process, reduce production costs, and achieve the goal of green manufacturing.

[0076] In addition, the dimensional change of the external gear bushing before and after heat treatment is within 2mm, which meets the standard requirements.

[0077] Comparative Example 1 This comparative example discloses a manufacturing process for the internal gear ring of a high-power wind turbine gear pair, which differs from Example 1 in that... In step S5, the final dimensions of the blank are φ2052×φ1756×606mm. The radial pressure is controlled to not exceed 18 MPa, and the radial pressure is gradually increased at a rate of 0.42 MPa / s. The axial pressure is controlled to not exceed 15 MPa, and the axial pressure is gradually increased at a rate of 0.44 MPa / s. After reaching the blank size, the pressure is slowly withdrawn. The metallographic structure of the obtained gear pair blank includes ferrite with a content of ≤10%, and the rest is austenite with a grain size of ≤6.

[0078] The calculation of radial pressure velocities V1 and V2 is based on the final dimensions φ2052×φ1756×606mm, and the calculation steps are as follows: V1≈k1(D / t) Mpa / s, where D is the outer diameter of the blank, which is 2052mm, t is the wall thickness of the blank, which is (2052-1756) / 2=148mm, and k1 is 0.03. The calculated radial pressure rate V1 is 0.42 Mpa / s. V2≈k2(H / D) Mpa / s, where H is the blank height, which is 606 mm, D is the blank outer diameter, which is 2052 mm, and k2 is 1.5. The calculated axial pressure rate V2 is 0.44 Mpa / s. During this process, the radial and axial pressure rates are too low, which means that it takes more time to roll the ring and expand the hole to the final size. This results in uneven stress and heating of the product, surface stress concentration, and uneven grain size with some coarse particles. The tensile strength of the product is less than 1000 MPa and the impact absorption energy is less than 110 KU2 / J.

[0079] In addition, due to numerous internal defects, the product's dimensions changed by more than 2mm before and after heat treatment, failing to meet the standard requirements.

[0080] Comparative Example 2 This comparative example discloses a manufacturing process for the external gear bushing of a high-power wind turbine gear pair, which differs from Example 1 in that... In step S5, the final dimensions of the blank are φ1899×φ1126×611mm. The radial pressure is controlled to not exceed 18 MPa, and the radial pressure is gradually increased at a rate of 0.29 MPa / s. The axial pressure is controlled to not exceed 15 MPa, and the axial pressure is gradually increased at a rate of 0.48 MPa / s. After reaching the blank size, the pressure is slowly withdrawn. The metallographic structure of the obtained product includes ferrite with a content of >10%, and the remainder is austenite with a grain size of ≤5.

[0081] The calculation of radial pressure velocities V1 and V2 is based on the final dimensions φ1899×φ1126×611mm, and the calculation steps are as follows: V1≈k1(D / t) Mpa / s, where D is the outer diameter of the blank, which is 1899 mm, t is the wall thickness of the blank, which is (1899-1126) / 2=386.5 mm, and k1 is 0.06. The calculated radial pressure rate V1 is 0.29 Mpa / s. V2≈k2(H / D) Mpa / s, where H is the blank height, which is 611 mm, D is the blank outer diameter, which is 1899 mm, and k2 is 2.1. The calculated axial pressure rate V2 is 0.68 Mpa / s. During this process, excessively high radial and axial pressure rates cause the ring to expand to the final size too quickly, resulting in uneven stress on the product. When the large-sized external gear bushing is expanded, the excessive speed leads to a large difference in internal and external stress, causing stress concentration on the surface. Furthermore, the particles cannot be refined, resulting in uneven grain size and some coarse particles. The resulting product has a tensile strength of less than 1000 MPa and an impact absorption energy of less than 110 KU2 / J.

[0082] In addition, due to numerous internal defects, the product's dimensions changed by more than 2mm before and after heat treatment, failing to meet the standard requirements.

[0083] The above description is merely a preferred embodiment of this application and an explanation of the technical principles used. Those skilled in the art should understand that the scope involved in this application is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept. For example, technical solutions formed by replacing the above-mentioned features with technical features with similar functions disclosed in this application (but not limited to) each other.

[0084] Apart from the technical features described in the specification, the other technical features are known to those skilled in the art. To highlight the innovative features of this invention, the other technical features will not be described in detail here.

Claims

1. A high-power wind turbine gear pair component, characterized in that, The raw materials used, in the following mass ratios, are: C: 0.38%-0.45%, Si: 0.17%-0.37%, Mn: 0.50%-0.80%, Ni: 0.50%-0.70%, Cr: 0.90%-1.20%, Mo: 0.15%-0.30%, with the remainder being Fe and unavoidable impurities.

2. The high-power wind turbine gear pair component according to claim 1, characterized in that, The gear pair component is a ring-shaped component with inner and outer diameters, and the tensile strength R of the gear pair component is... m ≥1000MPa, yield strength Rp 0.2 ≥800Mpa, elongation after fracture A≥14%, reduction of area Z≥50%, impact absorption energy≥110KU2 / J.

3. A manufacturing process for a high-power wind turbine gear pair component, comprising the steps of: material preparation, continuous casting, forging, punching, ring rolling and reaming, and quenching and tempering heat treatment, characterized in that, In the ring rolling and hole enlarging step, the radial pressure is controlled to gradually increase until the blank size is reached, and then the pressure is withdrawn. The maximum radial pressure does not exceed 18 MPa, and the radial pressure rate satisfies: V1≈k1(D / t) MPa / s. The axial pressure is gradually increased until it reaches the blank size, and then the pressure is withdrawn. The maximum axial pressure does not exceed 15 MPa, and the axial pressure rate satisfies: V2≈k2(H / D) MPa / s. The blank is obtained by the ring rolling and hole expansion step. In the formula, D is the outer diameter of the blank, H is the height of the blank, and t is the wall thickness of the blank, all in mm; k1 is the empirical coefficient of radial pressure rate, and k2 is the empirical coefficient of axial pressure rate, both in MPa / (s·mm). The radial pressure is greater than the axial pressure; the pressure rate coefficient k1 ranges from 0.04 to 0.05, and the value of k2 ranges from 1.6 to 1.

8.

4. The manufacturing process according to claim 3, characterized in that, In the punching step, punching removes the loose area in the middle of the continuously cast billet and shapes it to meet the ratio of hole diameter to outer diameter of circle ≥ 1:

4.

5. The manufacturing process according to claim 3, characterized in that, The product after ring rolling and hole expansion undergoes quenching and tempering heat treatment, which includes a quenching step and a tempering step. The quenching step includes: heating to 400±10℃ and holding at that temperature for 4±0.5h; Heat to 650±10℃ and hold for 3±0.5 hours; Heat to 850±10℃ and hold for 5±0.5 hours; cool down; The tempering step includes: Heat to 400±10℃ and hold for 4±0.5 hours; Heat to 590±10℃ and hold for 6±0.5 hours; cool down.

6. The manufacturing process according to claim 3, characterized in that, In the continuous casting step, the temperature is controlled at 1600~1700℃, and the BOF+LF+RH+CCM process is used to produce a continuously cast billet, which includes the following steps: a) BOF converter steelmaking: using molten iron obtained from the batching process as raw material, high-pressure oxygen is introduced, and oxygen blowing is used for decarburization and dephosphorization for 15-20 minutes, controlling the dephosphorization rate to ≥95%; b) LF ladle refining: bottom blowing argon stirring, desulfurization and alloying, temperature precision control within ±5℃, processing time 30~60 minutes, sulfur content controlled ≤0.005%; c) RH vacuum circulation degassing: vacuum degree controlled ≤1mbar, circulation driven by argon, molten steel circulation rate is 80~120 tons / minute, processing time is 15~25 minutes, hydrogen content controlled ≤1.0ppm, oxygen content controlled ≤15ppm; d) CCM continuous casting: superheat control is 15~30℃, stirring, and argon protection throughout the casting process.

7. The manufacturing process according to claim 3, characterized in that, In the forging process, the continuously cast billet is compacted by upsetting and drawing, the upsetting-drawing length ratio is controlled to be ≥3, and the temperature is controlled at 1150-1200℃.

8. A high-power wind turbine gear pair component, characterized in that, The gear pair part is manufactured according to any one of claims 3-7, and is an annular part with inner and outer bore diameters. The tensile strength R of the gear pair part is... m ≥1000MPa, yield strength Rp 0.2 ≥800Mpa, elongation after fracture A≥14%, reduction of area Z≥50%, impact absorption energy≥110KU2 / J.

9. The high-power wind turbine gear pair component according to claim 8, characterized in that, The gear pair component has an inner diameter of 800-1900mm, an outer diameter of 1500-2200mm, and an inner-outer diameter ratio of 0.36-0.

90.

10. The high-power wind turbine gear pair component according to claim 9, characterized in that, The metallographic structure of the gear pair components includes ≥95% sorbite, with the remainder being bainite, and the grain size of the gear pair components is ≥7.

11. The high-power wind turbine gear pair component according to claim 10, characterized in that, The dimensional changes of the gear pair parts before and after heat treatment are within 2mm.

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