Preparation method of multi-stage forging high-temperature alloy material and preparation method of multi-stage forging high-temperature alloy material

Abstract

The invention relates to the field of high-temperature alloys, and provides a preparation method of a multi-stage forged high-temperature alloy material, which comprises the steps of alloy ingot pretreatment, multi-stage forging forming, finished product annealing and multi-stage heat treatment. The method comprises the following steps: firstly, smelting an Inconel 718 alloy ingot in a vacuum induction smelting furnace, and casting into a plate; and then, through multi-stage forging processes such as primary rolling, intermediate annealing, finish rolling, secondary annealing and finish rolling, grains of the alloy plate are gradually refined, the texture is optimized, and the mechanical property and the structure stability of the material are improved. And the finished product annealing stage is carried out under argon protection so as to eliminate the processing stress and improve the comprehensive performance of the material. Finally, a uniformly dispersed micro-nano structure is achieved through solution treatment and two-stage aging, multi-stage forging and optimized heat treatment design are adopted, high strength, high toughness and high-temperature stability of the high-temperature alloy foil material are achieved, the problems that a precipitated phase is difficult to accurately regulate and control and an ultrathin foil material is difficult to prepare in a traditional process are solved, and the method is suitable for large-scale industrial production. And the method has wide application value.

Description

Technical Field

[0001] The invention relates to the field of high-temperature alloys, and in particular to a multi-stage forged high-temperature alloy material and a preparation method thereof. Background Art

[0002] As a key material in the fields of aerospace, energy and advanced manufacturing, high-temperature alloy foil plays a vital role in extreme environments. For example, in applications such as aircraft engines, hot end components of gas turbines and high-temperature sensors, high-temperature alloy foil can effectively improve the safety and operating efficiency of the system due to its excellent high-temperature resistance, oxidation resistance and high strength. However, these application scenarios are usually accompanied by high temperature, high stress and complex working conditions, which put forward extremely stringent requirements on the mechanical properties, organizational stability and long-life service of the foil. In particular, under high temperature conditions, the material must not only have good creep resistance and fatigue resistance, but also maintain excellent toughness to prevent early failure caused by microcrack propagation. In addition, with the rapid development of advanced manufacturing technology, the thickness requirements of high-temperature alloy foil are becoming more and more stringent, and the trend of ultra-thinning is becoming more and more obvious, which poses higher challenges to the uniformity, organizational stability and machinability of the material. Therefore, how to ensure high-temperature strength while taking into account toughness, ensure the stability of the material in extreme environments, and meet the needs of precision manufacturing has become an important direction for promoting the development of high-temperature alloy foil. In response to these key needs, optimizing the material's microstructure, regulating the distribution and morphology of the precipitated phase, and improving the forging forming ability are the core goals of current high-temperature alloy foil research.

[0003] At present, the development of high-temperature alloy foils still faces many challenges, especially in terms of strength, toughness and forging. For example, the Chinese patent with publication number CN111850348B discloses a high-strength and high-toughness nickel-based high-temperature alloy foil and its preparation method, but there are still some shortcomings, mainly reflected in the difficulty in balancing high-temperature strength and toughness, and the uniformity and stability of the ultra-thin foil structure still need to be improved. When controlling the precipitation of strengthening phases such as γ' phase and γ” phase, the existing process is often difficult to accurately control their size, volume fraction and distribution, resulting in a certain contradiction between the creep resistance and fracture toughness of the material under high temperature conditions. In addition, the traditional multi-stage forging process is prone to cause cracks or defects due to work hardening and texture heterogeneity during the preparation of ultra-thin foil, reducing the yield rate and service life. Although some studies have attempted to improve these problems by optimizing the heat treatment system or introducing trace alloying elements, it is still difficult to achieve uniform microstructure control in thin-gauge foils while taking into account high-temperature stability and machinability. Therefore, how to further optimize the distribution and evolution mechanism of the precipitated phases through precise thermomechanical treatment and microstructure control strategies, improve the comprehensive performance of the foil, and achieve the synergistic enhancement of high strength, high toughness and high-temperature stability is still a key technical problem that needs to be solved in this field. Summary of the invention

[0004] (1) Technical issues solved

[0005] The purpose of the present invention is to provide a multi-stage forged high-temperature alloy material and a preparation method thereof, so as to solve the technical bottlenecks existing in the current high-temperature alloy materials in terms of strength-toughness matching, organizational stability and ultra-thin foil preparation.

[0006] (2) Technical solution

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A method for preparing a multi-stage forged high-temperature alloy material comprises the following steps:

[0009] S1. Alloy ingot pretreatment: Commercial Inconel 718 alloy ingot raw materials are placed in a vacuum induction melting furnace for melting, and then cast into plates with a thickness of 2.0 to 3.0 mm;

[0010] S2. Multi-stage forging: The plate of S1 is subjected to primary rolling, intermediate annealing, finish rolling, secondary annealing and final rolling in sequence to obtain foil;

[0011] S3 finished product annealing: the foil of S2 is subjected to finished product annealing to obtain an annealed foil;

[0012] S4. Multi-stage heat treatment: The annealed foil of S3 is subjected to solution treatment and two-stage aging in sequence to finally obtain a multi-stage forged high-temperature alloy material.

[0013] Furthermore, the smelting parameters of step S1 are: heating to 1550-1580° C. at a heating rate of 15-20° C. / min under a vacuum degree of 10-3 Pa, and keeping the temperature for 30-40 minutes.

[0014] Further, the parameters of the initial rolling in step S2 are: using a four-roll reversible cold rolling mill, setting a rolling force of 800-1000 kN, rolling the 2.0-3.0 mm plate to 0.35-0.65 mm in 6-8 passes, a rolling speed of 8-12 m / min, and a surface roughness Ra≤0.8 μm;

[0015] Further, the parameters of the intermediate annealing in step S2 are: under an argon protective atmosphere, the annealing temperature is 945-955° C., the annealing time is 8-12 min, and after the annealing is completed, air cooling is performed at an air cooling rate of 30-35° C. / s;

[0016] Further, the parameters of the finishing rolling in step S2 are: using a twenty-high rolling mill, with a rolling force of 200-300 kN, rolling the 0.35-0.45 mm plate to 0.25-0.30 mm in 15-20 passes;

[0017] Further, the parameters of the secondary annealing in step S2 are: under an argon protective atmosphere, the annealing temperature is 915-925° C., the annealing time is 8-12 min, and air cooling is performed after the annealing is completed, and the air cooling rate is 30-35° C. / s;

[0018] Further, the parameters of the final rolling in step S2 are: rolling the secondary annealed sheet into a foil of 0.05-0.08 mm with a thickness tolerance of ±1.5 μm;

[0019] The present invention adopts the S2 multi-stage forging design mainly to enhance the uniformity of the organization and high-temperature mechanical properties of high-temperature alloy materials. Through the synergistic effect of multi-stage rolling and segmented annealing, high rolling force and multi-pass deformation are used in the initial rolling stage to achieve grain refinement and dislocation density control. Rapid air cooling under argon protection during the intermediate annealing process inhibits the formation of coarse precipitation phases while retaining the work hardening effect; low rolling force and multi-pass progressive deformation are used in the finishing rolling stage, combined with secondary annealing to optimize the distribution of grain boundary characteristics, and finally the stable microstructure of ultra-thin foil is obtained through final rolling.

[0020] Furthermore, the parameters of the finished product annealing in step S3 are as follows: placing the final rolled foil in a tubular furnace, heating it to 945-955° C. at 30-50° C. / min under argon protection, keeping it warm for 10-14 minutes, and then cooling it to room temperature.

[0021] The present invention adopts the design of S3 finished annealing mainly to enhance the microstructural uniformity and high-temperature stability of high-temperature alloy materials. Through rapid heating and precise temperature control under argon protection, on the basis of the specific dislocation structure formed by initial rolling, fine rolling and final rolling, the finished annealing process coordinates the recrystallization behavior through short-term high-temperature insulation and furnace cooling, which not only eliminates the residual stress introduced by the previous rolling, but also retains an appropriate amount of substructure to promote the uniform nucleation of subsequent aging precipitation phases. In the multi-stage heat treatment, the solution treatment optimizes the distribution of solute elements in the γ matrix through gradient heating, and the two-stage aging uses the difference in temperature sequence to regulate the size matching and spatial arrangement of the γ' phase and the γ" phase, wherein the differentiated distribution of the γ" phase inside the grain and at the grain boundary and the grain boundary segregation of the δ phase form a multi-scale strengthening network. As a stable second phase, the NbC phase improves the creep resistance of the material by pinning dislocations and hindering grain boundary migration. The specific volume ratio of γ' phase and γ" phase and the interface coherence relationship, combined with the geometric morphology and distribution characteristics of δ phase, achieve the synergistic enhancement of precipitation phase strengthening, grain boundary strengthening and dislocation strengthening. This multi-level structural control system dynamically matches the rolling process and heat treatment parameters, so that the precipitation phase morphology, grain boundary characteristics and grain size form a spatially complementary strengthening mechanism, thereby comprehensively improving the comprehensive performance of the material under high temperature and complex stress conditions.

[0022] Furthermore, the parameters of the solution treatment in step S4 are: solution treatment at 900-905° C. for 240-260 min in an argon protective atmosphere, then increasing the temperature to 960-970° C. at a heating rate of 20° C. / min, and keeping the temperature for 50-60 min.

[0023] Furthermore, the parameters of the double-stage aging in step S4 are: first, primary aging at 720-730° C. for 420-480 min; and then secondary aging at 620-630° C. for 420-480 min.

[0024] In the S4 multi-stage heat treatment of the present invention, the solution treatment promotes the uniform diffusion of solute elements in the γ matrix by staged temperature control, and the two-stage aging regulates the coordinated precipitation behavior of the γ' phase and the γ" phase by temperature gradient, wherein the directional distribution of the γ" phase at the grain boundary and inside the grain and the grain boundary pinning effect of the δ phase form a multi-level strengthening network. As a stable second phase, the NbC phase enhances the creep resistance of the material by interacting with dislocations. The volume ratio control and coordinated optimization of the spatial distribution of the γ' phase and the γ" phase complement each other in the precipitation phase strengthening and grain boundary strengthening mechanisms, and the geometric arrangement of the δ phase and the size distribution of the NbC phase further enhance the organizational stability under high temperature environments. This multi-scale structural control system achieves the coordinated matching of precipitation phase morphology, grain boundary characteristics and dislocation configuration through the coupling design of rolling process and heat treatment parameters, thereby comprehensively improving the comprehensive performance of the material under complex thermomechanical loads.

[0025] The present invention also discloses a multi-stage forged high-temperature alloy material, wherein the multi-stage forged high-temperature alloy material is obtained by adopting the above-mentioned preparation method;

[0026] The multi-stage forged high-temperature alloy material contains γ' phase and γ" phase; the γ' phase and γ" phase are disc-shaped nano-precipitated phases with an average diameter of 15-20 nm; the volume ratio of the γ' phase to the γ" phase is 1:(2.0-3.0);

[0027] The multi-stage forged high-temperature alloy material contains a δ phase, which is needle-shaped or short rod-shaped with an average length of 200 to 500 nm;

[0028] The multi-stage forged high-temperature alloy material contains NbC phase, which is spherical or cubic and has an average size of 50 to 200 nm;

[0029] The average diameter of the multi-stage forged high-temperature alloy material is 2.5-3.0 μm.

[0030] The present invention adopts the design of S4 multi-stage heat treatment mainly to enhance the multi-phase synergistic strengthening effect and high-temperature structural stability of high-temperature alloy materials. Through the coordinated control of the temperature sequence of solution treatment and two-stage aging, on the basis of the uniform matrix formed by the finished product annealing, the segmented heating strategy in the solution stage promotes the gradient diffusion of elements such as Nb and Mo in the γ matrix, providing optimized component segregation conditions for subsequent aging precipitation; the first-stage aging induces the differential nucleation of the γ" phase at the grain boundary and in the crystal through long-term heat preservation in the medium temperature zone, and its disk-like morphology and the coherent strain field of the matrix produce a dislocation pinning effect, and the second-stage aging regulates the precipitation of the δ phase along a specific crystal plane in the low temperature zone, and the needle-like structure forms a three-dimensional strengthening network through geometric interlacing with the γ" phase. As an inert second phase, the NbC phase inhibits abnormal grain growth at the grain boundary through the Zener pinning mechanism, and forms a size-complementary barrier system with the γ” phase in the grain to jointly hinder dislocation movement. The specific volume ratio design of the γ' phase and the γ” phase couples the precipitation dynamics of the two phases. The high-density distribution of the γ” phase makes up for the defect of the insufficient high-temperature softening resistance of the γ' phase, and the aspect ratio control of the δ phase balances the grain boundary strengthening and brittleness risks. This multiphase system achieves multi-level synergy of coherent precipitation strengthening, grain boundary engineering strengthening and second phase dispersion strengthening through precipitation sequence control, morphology matching and spatial distribution optimization, so that the matrix organization maintains dimensional stability and defect tolerance under high-temperature stress, thereby comprehensively improving the service performance of the material in extreme thermal-mechanical coupling environments.

[0031] (3) Beneficial technical effects

[0032] 1. The present invention achieves grain refinement and dislocation density regulation by synergistic optimization of multi-stage rolling and segmented annealing. In the initial rolling stage, high rolling force and multi-pass deformation are used to achieve grain refinement and dislocation density regulation. Intermediate annealing is combined with argon protection and rapid air cooling to suppress coarse precipitate phases and retain work hardening effect. In the finishing rolling stage, low rolling force and progressive deformation are combined with secondary annealing to optimize grain boundary distribution. Ultra-thin foil with uniform structure is obtained by final rolling. Compared with the traditional single-stage rolling process, the industry problems of coarse grains and uneven distribution of precipitate phases in high-temperature alloy materials are effectively solved. The present invention is particularly suitable for high-temperature load-bearing components such as aerospace engine blades. The triple synergy of grain refinement, precipitate phase regulation and grain boundary strengthening is achieved by precise matching of rolling force gradient control and annealing parameters, which significantly improves the high-temperature stability and creep resistance of the material.

[0033] 2. The present invention achieves rapid heating and precise temperature control under argon protection during finished product annealing, combined with gradient temperature control of solution treatment and two-stage aging phase transformation regulation, while eliminating rolling residual stress, retaining substructure and promoting uniform nucleation of γ" phase. Compared with traditional single-stage annealing technology, it effectively solves the industry pain points of uneven distribution of precipitation phase and insufficient high-temperature stability of high-temperature alloy materials, and is particularly suitable for high-temperature load-bearing components such as aircraft engine turbine blades. It forms a multi-scale strengthening network through the differentiated distribution of γ" phase intracrystalline / grain boundary and the segregation of δ phase grain boundary, synergistic pinning effect of NbC phase and coherent strengthening of γ' phase, to achieve triple synergistic strengthening of precipitation phase, grain boundary and dislocation. The precise matching of heat treatment parameters and rolling strain significantly improves the material's high-temperature creep resistance, providing key material support for the new generation of aerospace power systems.

[0034] 3. The present invention coordinates the segmented temperature control of the solution treatment in the multi-stage heat treatment with the two-stage aging temperature sequence to accurately control the gradient precipitation of the γ" phase at the grain boundary / inside the grain and the construction of the three-dimensional strengthening network of the δ phase. Compared with the traditional single-stage aging technology, it effectively solves the industry bottleneck that it is difficult to balance the creep resistance and organizational stability of high-temperature alloys. It is particularly suitable for extreme thermal-mechanical coupling components such as aircraft engine turbine disks. Through the multi-phase synergistic mechanism of γ" phase coherent strain field pinning dislocations, δ phase geometric interlacing hindering crack propagation, and NbC phase Zener pinning inhibiting grain coarsening, combined with the optimization of the volume ratio of γ' phase to γ" phase and the control of the aspect ratio of δ phase, cross-scale matching of precipitated phase morphology, grain boundary structure and defect configuration is achieved. The precise coupling of its temperature sequence and element diffusion dynamics enables the material to have both high strength and high damage tolerance under high temperature and complex loads, providing a key material solution for the new generation of high thrust-to-weight ratio aircraft engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a physical picture of the multi-stage forged high-temperature alloy material prepared in Example 1 of the present invention.

[0036] Figure 2 This is a microstructure morphology diagram of the multi-stage forged high-temperature alloy material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0037] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0038] Example 1

[0039] A method for preparing a multi-stage forged high-temperature alloy material comprises the following steps:

[0040] S1. Alloy ingot pretreatment: Commercial Inconel 718 alloy ingot raw materials were placed in a vacuum induction melting furnace for melting, and then cast into plates with a thickness of 2.0 mm; the melting parameters were: under a vacuum degree of 10-3 Pa, heated to 1550°C at a heating rate of 15°C / min, and kept warm for 35 minutes.

[0041] S2. Multi-stage forging forming: The plate of S1 is subjected to primary rolling, intermediate annealing, finishing rolling, secondary annealing and final rolling in sequence to obtain foil; the parameters of the primary rolling are: using a four-roll reversible cold rolling mill, setting the rolling force to 850kN, rolling the 2.0mm plate to 0.38mm in 6 passes, the rolling speed is 9m / min, and the surface roughness Ra≤0.8μm; the parameters of the intermediate annealing are: under an argon protective atmosphere, the annealing temperature is 950℃, the annealing time is 10min, and air cooling is performed after annealing is completed, and the air cooling rate is 32℃ / s. The parameters of finishing rolling are: using a twenty-high rolling mill with a rolling force of 220kN, rolling the 0.38mm plate to 0.26mm in 16 passes; the parameters of secondary annealing are: under argon protective atmosphere, the annealing temperature is 920℃, the annealing time is 10min, and air cooling is performed after annealing, and the air cooling rate is 32℃ / s; the parameters of final rolling are: rolling the secondary annealed plate to 0.06mm foil, with a thickness tolerance of ±1.5μm.

[0042] S3. Finished product annealing: The foil of S2 is subjected to finished product annealing to obtain annealed foil; the parameters of the finished product annealing are as follows: the final rolled foil is placed in a tubular furnace, heated to 950°C at 35°C / min under argon protection, kept at this temperature for 12 minutes, and then cooled to room temperature in the furnace.

[0043] S4. Multi-stage heat treatment: The annealed foil of S3 is subjected to solution treatment and two-stage aging in sequence to finally obtain a multi-stage forged high-temperature alloy material; the parameters of the solution treatment are: solution treatment at 900°C for 250 min in an argon protective atmosphere, then the temperature is increased to 965°C at a heating rate of 20°C / min and kept at this temperature for 55 min; the parameters of the two-stage aging are: first, aging at 725°C for 450 min for primary aging; then aging at 625°C for 450 min for secondary aging.

[0044] The multi-stage forged high-temperature alloy material of this embodiment contains γ' phase and γ" phase; the γ' phase and γ" phase are disc-shaped nano-precipitation phases with an average diameter of 15nm; the volume ratio of the γ' phase and the γ" phase is 1:2.0; the multi-stage forged high-temperature alloy material contains δ phase, which is needle-shaped or short rod-shaped with an average length of 200nm; the multi-stage forged high-temperature alloy material contains NbC phase, which is spherical or cubic with an average of 52nm; the average diameter of the multi-stage forged high-temperature alloy material is 2.5μm.

[0045] Figure 1The actual picture of the multi-stage forged high-temperature alloy material prepared in Example 1 of the present invention is shown, which proves that the high-temperature alloy foil is successfully prepared by the process method, indicating that the method is feasible in actual production. Figure 2 The microstructure morphology of the multi-stage forged high-temperature alloy material prepared in Example 1 shows that the microstructure of the material is uniformly distributed, the grains are fine and there is no obvious segregation, which further proves that the method of the present invention can optimize the microstructure of the alloy and improve the performance stability of the material. Based on the above results, it is shown that the multi-stage forging and heat treatment process proposed in the present invention can effectively control the microstructure of the high-temperature alloy foil, achieve high uniformity, high strength and excellent high-temperature performance, and meet the application requirements of high-temperature service environments such as aerospace.

[0046] Example 2

[0047] A method for preparing a multi-stage forged high-temperature alloy material comprises the following steps:

[0048] S1. Alloy ingot pretreatment: Commercial Inconel 718 alloy ingot raw materials were placed in a vacuum induction melting furnace for melting, and then cast into plates with a thickness of 2.3 mm; the melting parameters were: under a vacuum degree of 10-3 Pa, heated to 1565°C at a heating rate of 17°C / min, and kept warm for 35 minutes.

[0049] S2. Multi-stage forging forming: The plate of S1 is subjected to primary rolling, intermediate annealing, finishing rolling, secondary annealing and final rolling in sequence to obtain foil; the parameters of the primary rolling are: using a four-roll reversible cold rolling mill, setting the rolling force to 900kN, rolling the 2.3mm plate to 0.45mm in 7 passes, the rolling speed is 11m / min, and the surface roughness Ra≤0.8μm; the parameters of the intermediate annealing are: under an argon protective atmosphere, the annealing temperature is 950℃, the annealing time is 10min, and air cooling is performed after annealing is completed, and the air cooling rate is 32℃ / s. The parameters of finishing rolling are: using a twenty-high rolling mill with a rolling force of 250kN, rolling the 0.45mm plate to 0.28mm in 18 passes; the parameters of secondary annealing are: under argon protective atmosphere, the annealing temperature is 920℃, the annealing time is 10min, and air cooling is performed after annealing, and the air cooling rate is 32℃ / s; the parameters of final rolling are: rolling the secondary annealed plate to 0.07mm foil, with a thickness tolerance of ±1.5μm.

[0050] S3. Finished product annealing: The foil of S2 is subjected to finished product annealing to obtain annealed foil; the parameters of the finished product annealing are as follows: the final rolled foil is placed in a tubular furnace, heated to 950°C at 40°C / min under argon protection, kept at this temperature for 12 minutes, and then cooled to room temperature in the furnace.

[0051] S4. Multi-stage heat treatment: The annealed foil of S3 is subjected to solution treatment and two-stage aging in sequence to finally obtain a multi-stage forged high-temperature alloy material; the parameters of the solution treatment are: solution treatment at 902°C for 250 min in an argon protective atmosphere, then the temperature is increased to 965°C at a heating rate of 20°C / min and kept at this temperature for 55 min; the parameters of the two-stage aging are: first, aging at 725°C for 450 min for primary aging; then aging at 625°C for 450 min for secondary aging.

[0052] The multi-stage forged high-temperature alloy material of this embodiment contains γ' phase and γ" phase; the γ' phase and γ" phase are disc-shaped nano-precipitation phases with an average diameter of 16nm; the volume ratio of the γ' phase and the γ" phase is 1:2.3; the multi-stage forged high-temperature alloy material contains δ phase, which is needle-shaped or short rod-shaped with an average length of 320nm; the multi-stage forged high-temperature alloy material contains NbC phase, which is spherical or cubic with an average size of 80nm; the average diameter of the multi-stage forged high-temperature alloy material is 2.7μm.

[0053] Example 3

[0054] A method for preparing a multi-stage forged high-temperature alloy material comprises the following steps:

[0055] S1. Alloy ingot pretreatment: Commercial Inconel 718 alloy ingot raw materials were placed in a vacuum induction melting furnace for melting, and then cast into plates with a thickness of 2.6 mm; the melting parameters were: under a vacuum degree of 10-3 Pa, heated to 1570°C at a heating rate of 18°C / min, and kept warm for 38 minutes.

[0056] S2. Multi-stage forging forming: The plate of S1 is subjected to primary rolling, intermediate annealing, finishing rolling, secondary annealing and final rolling in sequence to obtain foil; the parameters of the primary rolling are: using a four-roll reversible cold rolling mill, setting the rolling force to 950 kN, rolling the 2.6 mm plate to 0.55 mm in 7 passes, the rolling speed is 12 m / min, and the surface roughness Ra ≤ 0.8 μm; the parameters of the intermediate annealing are: under an argon protective atmosphere, the annealing temperature is 952 ° C, the annealing time is 11 min, and air cooling is performed after annealing is completed, and the air cooling rate is 33 ° C / s. The parameters of finishing rolling are: using a twenty-high rolling mill with a rolling force of 280kN, the 0.55mm plate is rolled to 0.29mm in 19 passes; the parameters of secondary annealing are: under argon protective atmosphere, the annealing temperature is 922℃, the annealing time is 11min, and air cooling is performed after annealing, and the air cooling rate is 33℃ / s; the parameters of final rolling are: rolling the secondary annealed plate to 0.07mm foil, with a thickness tolerance of ±1.5μm.

[0057] S3. Finished product annealing: The foil of S2 is subjected to finished product annealing to obtain annealed foil; the parameters of the finished product annealing are as follows: the final rolled foil is placed in a tubular furnace, heated to 952°C at 45°C / min under argon protection, kept at this temperature for 13 minutes, and then cooled to room temperature in the furnace.

[0058] S4. Multi-stage heat treatment: The annealed foil of S3 was subjected to solution treatment and two-stage aging in sequence to finally obtain a multi-stage forged high-temperature alloy material; the parameters of the solution treatment were: solution treatment at 903°C for 255 min in an argon protective atmosphere, followed by increasing the temperature to 968°C at a heating rate of 20°C / min and keeping the temperature for 58 min; the parameters of the two-stage aging were: first, aging at 728°C for 470 min for primary aging; then, aging at 628°C for 470 min for secondary aging.

[0059] The multi-stage forged high-temperature alloy material of this embodiment contains γ' phase and γ" phase; the γ' phase and γ" phase are disc-shaped nano-precipitation phases with an average diameter of 18nm; the volume ratio of the γ' phase and the γ" phase is 1:2.7; the multi-stage forged high-temperature alloy material contains δ phase, which is needle-shaped or short rod-shaped with an average length of 450nm; the multi-stage forged high-temperature alloy material contains NbC phase, which is spherical or cubic with a size of 160nm; the average diameter of the multi-stage forged high-temperature alloy material is 2.9μm.

[0060] Example 4

[0061] A method for preparing a multi-stage forged high-temperature alloy material comprises the following steps:

[0062] S1. Alloy ingot pretreatment: Commercial Inconel 718 alloy ingot raw materials were placed in a vacuum induction melting furnace for melting, and then cast into a plate with a thickness of 3.0 mm; the melting parameters were: under a vacuum degree of 10-3 Pa, heated to 1580°C at a heating rate of 20°C / min, and kept warm for 40 minutes.

[0063] S2. Multi-stage forging forming: The plate of S1 is subjected to primary rolling, intermediate annealing, finishing rolling, secondary annealing and final rolling in sequence to obtain foil; the parameters of the primary rolling are: using a four-roll reversible cold rolling mill, setting the rolling force to 980kN, rolling the 3.0mm plate to 0.62mm in 8 passes, the rolling speed is 12m / min, and the surface roughness Ra≤0.8μm; the parameters of the intermediate annealing are: under argon protective atmosphere, the annealing temperature is 955℃, the annealing time is 12min, and air cooling is performed after annealing is completed, and the air cooling rate is 35℃ / s. The parameters of finishing rolling are: using a twenty-high rolling mill with a rolling force of 290kN, the 0.62mm plate is rolled to 0.30mm in 20 passes; the parameters of secondary annealing are: under argon protective atmosphere, the annealing temperature is 925℃, the annealing time is 12min, and air cooling is performed after annealing, and the air cooling rate is 35℃ / s; the parameters of final rolling are: rolling the secondary annealed plate to 0.08mm foil, with a thickness tolerance of ±1.5μm.

[0064] S3. Finished product annealing: The foil of S2 is subjected to finished product annealing to obtain annealed foil; the parameters of the finished product annealing are as follows: the final rolled foil is placed in a tubular furnace, heated to 955°C at 50°C / min under argon protection, kept at this temperature for 14 minutes, and then cooled to room temperature in the furnace.

[0065] S4. Multi-stage heat treatment: The annealed foil of S3 is subjected to solution treatment and two-stage aging in sequence to finally obtain a multi-stage forged high-temperature alloy material; the parameters of the solution treatment are: solution treatment at 905°C for 260 min in an argon protective atmosphere, then the temperature is increased to 970°C at a heating rate of 20°C / min and kept at this temperature for 60 min; the parameters of the two-stage aging are: first, aging at 730°C for 480 min for primary aging; then aging at 630°C for 480 min for secondary aging.

[0066] The multi-stage forged high-temperature alloy material of this embodiment contains γ' phase and γ" phase; the γ' phase and γ" phase are disc-shaped nano-precipitation phases with an average diameter of 20nm; the volume ratio of the γ' phase and the γ" phase is 1:3.0; the multi-stage forged high-temperature alloy material contains δ phase, which is needle-shaped or short rod-shaped with an average length of 500nm; the multi-stage forged high-temperature alloy material contains NbC phase, which is spherical or cubic with an average size of 200nm; the average diameter of the multi-stage forged high-temperature alloy material is 3.0μm.

[0067] Comparative Example 1

[0068] It is basically the same as Example 1, except that during the initial rolling process of S2, the rolling force is reduced to 600 kN and the number of passes is reduced to 4.

[0069] Comparative Example 2

[0070] It is basically the same as Example 1, except that in the intermediate annealing process S2, the annealing temperature is increased to 980° C. and the annealing time is extended to 20 min.

[0071] Comparative Example 3

[0072] It is basically the same as Example 1, except that during the S2 finishing rolling, the rolling speed is increased to 20m / min and the rolling force is reduced to 150kN.

[0073] Comparative Example 4

[0074] It is basically the same as Example 1, except that during the S2 final rolling process, the final thickness is adjusted to 0.10 mm.

[0075] Comparative Example 5

[0076] It is basically the same as Example 1, except that during the annealing process of the S3 finished product, the heating rate is reduced to 10°C / min and the holding time is extended to 30min.

[0077] Comparative Example 6

[0078] It is basically the same as Example 1, except that during the S4 solution treatment, the holding temperature is reduced to 880°C and the holding time is shortened to 180 min.

[0079] Comparative Example 7

[0080] It is basically the same as Example 1, except that in the S4 two-stage aging process, the primary aging temperature is increased to 750°C, and the secondary aging temperature is reduced to 600°C.

[0081] Performance Test:

[0082] High temperature tensile performance test: Cut the high temperature alloy material into standard tensile specimens, refer to GB / T4338-2006 "Metallic Material High Temperature Tensile Test Method", and perform tensile tests on a Gleeble thermal simulator or a high temperature electronic universal testing machine. The test temperatures are set to room temperature, 650℃, 750℃ and 850℃, and the tensile rate is set to 0.001s-1 to determine the yield strength, tensile strength and elongation at break of the material. Through high temperature tensile tests, the strength retention and plasticity changes of alloy foils at different service temperatures are evaluated to provide data support for their application in high temperature environments.

[0083] Creep performance test: The high-temperature alloy material is cut into specimens with a size of 10mm×50mm, and a constant tensile stress of 150MPa and 200MPa is applied at 650℃, 700℃ and 750℃ respectively to conduct a long-term creep test. The creep tester is used to record the evolution curve of the strain over time, and the steady-state creep rate and creep life are analyzed. Through this experiment, the creep resistance of the alloy foil under high-temperature and long-term service conditions can be evaluated, providing reliability data for applications such as turbine blades and hot end components of gas turbines.

[0084] High temperature oxidation performance test: The prepared foil samples were cut into 20mm×20mm samples and subjected to isothermal oxidation tests in an air environment at 1000℃, with oxidation times set to 50h, 100h and 200h respectively. This experiment was used to evaluate the oxidation resistance of the alloy foil, optimize the alloy composition and surface treatment process, and improve the durability of the material in a high temperature environment.

[0085] Fatigue performance test: using the high temperature low cycle fatigue (LCF) test method, at 700 ° C, a strain-controlled sinusoidal load (strain amplitude ± 0.5% ~ ± 1.0%) was applied to the foil sample of Example 1, and the frequency was set to 0.5 Hz. The fatigue life (number of cycles) of the test sample was tested. This experiment can reveal the life and failure mode of the material under cyclic load, which is of great significance for applications in high temperature vibration environments (such as aircraft engine blades).

[0086] The properties of the high temperature alloy materials of Examples 1 to 4 and Comparative Examples 1 to 7 are summarized in Table 1.

[0087] Table 1 Performance of high temperature alloy materials of Examples 1 to 7 and Comparative Examples 1 to 7

[0088]

[0089] As can be seen from Table 1, different process parameters have a significant effect on the microstructure and properties of high-temperature alloys. Reducing the rolling force and reducing the number of passes will lead to insufficient deformation, reduced grain refinement, and thus reduced tensile strength, yield strength and creep life. At the same time, due to increased microstructure heterogeneity, fatigue life will also decrease, and the increase in the size of the precipitated phase may slightly increase the weight gain of high-temperature oxidation. Excessive annealing temperature and long time will lead to abnormal grain growth, which will reduce the high-temperature strength and creep life of the material. At the same time, the δ phase will coarsen, which will significantly increase the weight gain of high-temperature oxidation and significantly reduce the fatigue life. During the finishing rolling process, excessively fast rolling speed and insufficient rolling force will cause uneven deformation, resulting in a decrease in the microstructure uniformity of the material, thereby reducing the strength and creep life, but fine grains may still be formed in local areas, and some properties are between the embodiment and other processes, with a slightly reduced fatigue life and slightly worse high-temperature oxidation performance. Increasing the final rolling thickness will affect the texture optimization effect, reduce the tensile strength and yield strength, but because the overall microstructure density is still high, the high-temperature oxidation performance does not change much, and the creep life and fatigue life are slightly reduced. When the finished product is annealed, the heating rate is reduced and the holding time is too long, which will lead to the coarsening of the precipitation phase, the strength and creep life of the material will decrease, but the plasticity will remain good, the high-temperature oxidation performance will not change much, and the fatigue life will decrease slightly. The reduction of the solution temperature or the shortening of the holding time will affect the degree of solid solution of the alloy elements, so that the precipitation of the γ' phase and the γ" phase will be inhibited, resulting in a decrease in high-temperature strength. At the same time, the size of the NbC phase will decrease, which will reduce the creep life. The uneven structure will increase the weight gain due to high-temperature oxidation, and the fatigue life will also decrease. During the aging process, if the primary aging temperature is too high, the γ' phase will coarsen and reduce the high-temperature strength, while if the secondary aging temperature is too low, it may inhibit the formation of the precipitation phase, affect the strength-toughness matching of the material, and greatly reduce the creep life. At the same time, the high-temperature oxidation weight gain is the largest, the fatigue life is the lowest, and the crack extension ability is most significantly reduced due to insufficient precipitation strengthening. Therefore, the reasonable optimization of rolling, annealing, solution and aging processes can significantly improve the strength, toughness and high-temperature stability of high-temperature alloy foils to meet the needs of aerospace and high-temperature service environments.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that all equivalent structural changes made under the concept of the present invention and using the contents of the present invention specification and drawings should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a multi-stage forged high-temperature alloy material, characterized in that: The following steps are involved: S1. Alloy ingot pretreatment: Commercial Inconel 718 alloy ingot raw materials are placed in a vacuum induction melting furnace for melting, and then cast into plates with a thickness of 2.0 to 3.0 mm; S2. Multi-stage forging: The plate of S1 is subjected to primary rolling, intermediate annealing, finish rolling, secondary annealing and final rolling in sequence to obtain foil; S3 finished product annealing: the foil of S2 is subjected to finished product annealing to obtain an annealed foil; S4. Multi-stage heat treatment: The annealed foil of S3 is subjected to solution treatment and two-stage aging in sequence to finally obtain a multi-stage forged high-temperature alloy material.

2. The method for preparing a multi-stage forged high-temperature alloy material according to claim 1, characterized in that: The smelting parameters of step S1 are: heating to 1550-1580° C. at a heating rate of 15-20° C. / min under a vacuum degree of 10-3 Pa, and keeping the temperature for 30-40 minutes.

3. The method for preparing a multi-stage forged high-temperature alloy material according to claim 1, characterized in that: The parameters of the initial rolling in step S2 are: using a four-roll reversible cold rolling mill, setting a rolling force of 800-1000 kN, rolling the 2.0-3.0 mm plate to 0.35-0.65 mm in 6-8 passes, a rolling speed of 8-12 m / min, and a surface roughness Ra≤0.8 μm.

4. The method for preparing a multi-stage forged high-temperature alloy material according to claim 1, characterized in that: The parameters of the intermediate annealing in step S2 are: under an argon protective atmosphere, the annealing temperature is 945-955° C., the annealing time is 8-12 minutes, and after the annealing is completed, air cooling is performed at an air cooling rate of 30-35° C. / s.

5. The method for preparing a multi-stage forged high-temperature alloy material according to claim 1, characterized in that: The parameters of the finishing rolling in step S2 are: using a twenty-high rolling mill, with a rolling force of 200-300 kN, and rolling the 0.35-0.45 mm plate to 0.25-0.30 mm in 15-20 passes.

6. The method for preparing a multi-stage forged high-temperature alloy material according to claim 1, characterized in that: The parameters of the secondary annealing in step S2 are: under an argon protective atmosphere, the annealing temperature is 915-925° C., the annealing time is 8-12 min, and air cooling is performed after the annealing is completed, and the air cooling rate is 30-35° C. / s.

7. The method for preparing a multi-stage forged high-temperature alloy material according to claim 1, characterized in that: The parameters of the final rolling in step S2 are: rolling the secondary annealed sheet into a foil of 0.05-0.08 mm with a thickness tolerance of ±1.5 μm.

8. A method for preparing a multi-stage forged high-temperature alloy material as described in claim 1, wherein the parameters of the finished product annealing in step S3 are: placing the final rolled foil in a tubular furnace, heating it to 945-955°C at 30-50°C / min under argon protection, keeping it warm for 10-14 minutes, and then cooling it to room temperature.

9. The method for preparing a multi-stage forged high-temperature alloy material according to claim 1, characterized in that: The parameters of the solution treatment in step S4 are: solution treatment at 900-905° C. for 240-260 min in an argon protective atmosphere, then increasing the temperature to 960-970° C. at a heating rate of 20° C. / min, and keeping the temperature for 50-60 min; The parameters of the double-stage aging in step S4 are: first, aging at 720-730° C. for 420-480 min for primary aging; then, aging at 620-630° C. for 420-480 min for secondary aging.

10. A multi-stage forged high-temperature alloy material, characterized in that: The multi-stage forged high-temperature alloy material is prepared by the preparation method described in any one of claims 1 to 9; The multi-stage forged high-temperature alloy material contains γ' phase and γ" phase; the γ' phase and γ" phase are disc-shaped nano-precipitated phases with an average diameter of 15-20 nm; the volume ratio of the γ' phase to the γ" phase is 1:(2.0-3.0); The multi-stage forged high-temperature alloy material contains a δ phase, which is needle-shaped or short rod-shaped with an average length of 200 to 500 nm; The multi-stage forged high-temperature alloy material contains NbC phase, which is spherical or cubic and has an average size of 50 to 200 nm; The average diameter of the multi-stage forged high-temperature alloy material is 2.5-3.0 μm.

Images