A multi-stage rolled high-temperature alloy material and its preparation method

Abstract

This invention relates to the field of high-temperature alloys, providing a multi-stage rolled high-temperature alloy material and its preparation method, including alloy ingot pretreatment, multi-stage rolling forming, finished product annealing, and multi-stage heat treatment. First, Inconel 718 alloy ingots are melted in a vacuum induction melting furnace and cast into plates. Subsequently, through multi-stage rolling processes including initial rolling, intermediate annealing, finish rolling, secondary annealing, and final rolling, the alloy plates gradually refine grain size and optimize texture, improving the material's mechanical properties and structural stability. The finished product annealing stage is carried out under argon protection to eliminate processing stress and improve the material's overall performance. Finally, through solution treatment and two-stage aging, a uniformly dispersed micro / nano structure is achieved. This invention, employing multi-stage rolling and optimized heat treatment design, achieves high strength, high toughness, and high-temperature stability in high-temperature alloy foil materials, solving the problems of precise control of precipitated phases and preparation of ultra-thin foils in traditional processes, and has broad application value.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloys, and more specifically to a multi-stage rolled high-temperature alloy material and its preparation method. Background Technology

[0002] High-temperature alloy foils, as key materials in aerospace, energy, and advanced manufacturing, play a crucial role in extreme environments. For example, in applications such as aero-engines, hot-end components of gas turbines, and high-temperature sensors, high-temperature alloy foils effectively improve system safety and operational efficiency due to their excellent high-temperature resistance, oxidation resistance, and high strength. However, these applications are typically accompanied by high temperatures, high stress, and complex operating conditions, placing extremely stringent requirements on the mechanical properties, microstructure stability, and long service life of the foils. In particular, under high-temperature conditions, materials must not only possess good creep resistance and fatigue resistance but also maintain excellent toughness to prevent early failure caused by microcrack propagation. Furthermore, with the rapid development of advanced manufacturing technologies, the thickness requirements for high-temperature alloy foils are becoming increasingly stringent, with a growing trend towards ultra-thin materials. This presents greater challenges to the material's uniformity, microstructure stability, and machinability. Therefore, ensuring both high-temperature strength and toughness, guaranteeing material stability in extreme environments, and meeting the demands of precision manufacturing has become a crucial direction for the development of high-temperature alloy foils. To address these key needs, optimizing the microstructure of materials, controlling the distribution and morphology of precipitated phases, and improving forging capabilities are all core objectives of current research on high-temperature alloy foils.

[0003] Currently, the development of high-temperature alloy foils still faces many challenges, particularly in terms of strength, toughness, and forging. For example, Chinese patent CN111850348B discloses a high-strength, high-toughness nickel-based high-temperature alloy foil and its preparation method, but it still has shortcomings. These mainly lie in the difficulty of simultaneously achieving high-temperature strength and toughness, and the need to improve the uniformity and stability of the microstructure of ultra-thin foils. Existing processes often struggle to precisely control the size, volume fraction, and distribution of reinforcing phases such as γ' and γ'' phases, leading to a contradiction between creep resistance and fracture toughness under high-temperature conditions. Furthermore, traditional multi-stage rolling processes are prone to cracking or defects due to work hardening and texture inhomogeneity during the preparation of ultra-thin foils, reducing yield and service life. Although some studies have attempted to improve these problems by optimizing heat treatment regimes or introducing trace alloying elements, it remains difficult to achieve uniform microstructure control in thin-gauge foils while simultaneously ensuring high-temperature stability and machinability. Therefore, how to further optimize the distribution and evolution mechanism of precipitated phases through precise thermomechanical treatment and microstructure control strategies, improve the overall performance of foil materials, and achieve synergistic enhancement of high strength, high toughness, and high temperature stability remains a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] (1) Technical problems to be solved

[0005] The purpose of this invention is to provide a multi-stage rolled high-temperature alloy material and its preparation method, thereby solving the technical bottlenecks in the current high-temperature alloy materials in terms of strength and toughness matching, microstructure stability, and ultra-thin foil preparation.

[0006] (2) Technical solution

[0007] To achieve the above objectives, the present invention provides the following technical solution:

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

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

[0010] S2. Multi-stage rolling forming: The S1 sheet is subjected to primary rolling, intermediate annealing, fine rolling, secondary annealing and final rolling in sequence to obtain foil material;

[0011] S3. Finished product annealing: The foil material from S2 is subjected to finished product annealing to obtain annealed foil material;

[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 multi-stage rolled high-temperature alloy material.

[0013] Furthermore, the melting parameters for step S1 are as follows: under a vacuum of 10⁻³ Pa, heat to 1550~1580℃ at a heating rate of 15~20℃ / min, and hold for 30~40 min.

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

[0015] Furthermore, the parameters for the intermediate annealing in step S2 are as follows: under an argon protective atmosphere, the annealing temperature is 945~955℃, the annealing time is 8~12min, and after annealing, air cooling is performed at a rate of 30~35℃ / s.

[0016] Furthermore, the parameters for the finishing rolling in step S2 are as follows: using a 20-roll mill, with a rolling force of 200~300 kN, the 0.35~0.45mm plate is rolled to 0.25~0.30 mm in 15~20 passes;

[0017] Furthermore, the parameters for the secondary annealing in step S2 are as follows: under an argon protective atmosphere, the annealing temperature is 915~925℃, the annealing time is 8~12min, and after annealing, air cooling is performed at a rate of 30~35℃ / s.

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

[0019] This invention employs an S2 multi-stage rolling design primarily to enhance the microstructure uniformity and high-temperature mechanical properties of high-temperature alloy materials. Through the synergistic effect of multi-stage rolling and segmented annealing, grain refinement and dislocation density control are achieved in the initial rolling stage using high rolling force and multiple passes of deformation. During intermediate annealing, rapid air cooling under argon protection suppresses the formation of coarse precipitates while preserving the work hardening effect. In the finish rolling stage, low rolling force and multiple passes of progressive deformation are used, combined with secondary annealing to optimize the distribution of grain boundary features. Finally, a stable microstructure of ultrathin foil is obtained through final rolling.

[0020] Furthermore, the parameters for the finished product annealing in step S3 are as follows: the final rolled foil is placed in a tube furnace, heated to 945-955°C at a rate of 30-50°C / min under argon protection, held at that temperature for 10-14 minutes, and then furnace cooled to room temperature.

[0021] This invention employs an S3 finished product annealing design primarily to enhance the microstructure uniformity and high-temperature stability of high-temperature alloy materials. Through rapid heating and precise temperature control under argon protection, based on the specific dislocation structures formed during initial rolling, finishing rolling, and final rolling, the finished product annealing process, through short-term high-temperature holding and furnace cooling, coordinates and regulates recrystallization behavior. This eliminates residual stress introduced by the earlier rolling process while retaining an appropriate amount of substructure to promote the uniform nucleation of precipitated phases during subsequent aging. In the multi-stage heat treatment, solution treatment optimizes the distribution of solute elements in the γ matrix through gradient heating, while two-stage aging utilizes temperature sequence differences to regulate the size matching and spatial arrangement of the γ' and γ'' phases. The differentiated distribution of the γ'' phase within the grains and at grain boundaries, along with the grain boundary segregation of the δ phase, forms a multi-scale strengthening network. The NbC phase, as a stable second phase, enhances the material's creep resistance by pinning dislocations and hindering grain boundary migration. By combining the specific volume ratio and interfacial coherence of the γ' and γ'' phases with the geometric morphology and distribution characteristics of the δ phase, a synergistic effect of precipitation strengthening, grain boundary strengthening, and dislocation strengthening is achieved. This multi-level structural control system, through dynamic matching of rolling process and heat treatment parameters, enables the morphology of precipitates, grain boundary characteristics, and grain size to form a spatially complementary strengthening mechanism, thereby comprehensively improving the overall performance of the material under high-temperature and complex stress conditions.

[0022] Furthermore, the parameters for the solution treatment in step S4 are as follows: under an argon protective atmosphere, the solution is treated at 900~905℃ for 240~260 min, and then the temperature is increased to 960~970℃ at a heating rate of 20℃ / min and held for 50~60 min.

[0023] Furthermore, the parameters for the two-stage aging in step S4 are as follows: firstly, aging at 720~730℃ for 420~480 minutes is performed as the first-stage aging; then, aging at 620~630℃ for 420~480 minutes is performed as the second-stage aging.

[0024] In the S4 multi-stage heat treatment of this invention, solution treatment promotes the uniform diffusion of solute elements in the γ matrix through staged temperature control, while two-stage aging regulates the synergistic precipitation behavior of the γ' and γ'' phases through temperature gradient control. The directional distribution of the γ'' phase within grain boundaries and grains, along with the grain boundary pinning effect of the δ phase, forms a multi-layered strengthening network. The NbC phase, as a stable second phase, enhances the material's creep resistance through interaction with dislocations. The synergistic optimization of the volume ratio and spatial distribution of the γ' and γ'' phases allows the precipitate strengthening and grain boundary strengthening mechanisms to complement each other. The geometric arrangement of the δ phase and the size distribution of the NbC phase further enhance the microstructure stability under high-temperature conditions. This multi-scale structural control system, through the coupled design of rolling process and heat treatment parameters, achieves synergistic matching of precipitate morphology, grain boundary characteristics, and dislocation configuration, thereby comprehensively improving the material's overall performance under complex thermomechanical loads.

[0025] This invention also discloses a multi-stage rolled high-temperature alloy material, which is obtained by the above-described preparation method;

[0026] The multi-stage rolled high-temperature alloy material contains a γ' phase and a γ'' phase; the γ' phase and the γ'' phase are disk-shaped nano-precipitates 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 rolled high-temperature alloy material contains a δ phase, which is needle-shaped or short rod-shaped with an average length of 200~500 nm.

[0028] The multi-stage rolled high-temperature alloy material contains an NbC phase, which is spherical or cubic in shape and has an average size of 50~200 nm.

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

[0030] This invention employs an S4 multi-stage heat treatment design primarily to enhance the multiphase synergistic strengthening effect and high-temperature microstructure stability of high-temperature alloy materials. Through coordinated temperature control of solution treatment and two-stage aging, based on the homogeneous matrix formed by final annealing, the segmented heating strategy in the solution stage promotes gradient diffusion of elements such as Nb and Mo in the γ matrix, providing optimized compositional segregation conditions for subsequent aging precipitation. The first-stage aging, through prolonged holding in the mid-temperature region, induces differentiated nucleation of the γ'' phase at grain boundaries and within the grains. Its disk-like morphology and the coherent strain field of the matrix generate a dislocation pinning effect. The second-stage aging, in the low-temperature region, regulates the precipitation of the δ phase along specific crystal planes. The needle-like structure forms a three-dimensional strengthening network through geometrical interpenetration with the γ'' phase. The NbC phase, as an inert second phase, inhibits abnormal grain growth at grain boundaries through the Zener pinning mechanism, while simultaneously forming a size-complementary barrier system with the γ'' phase within the grains, jointly hindering dislocation movement. The specific volume ratio design of the γ' phase and the γ'' phase couples their precipitation kinetics. The high density distribution of the γ'' phase compensates for its insufficient resistance to high-temperature softening, while the aspect ratio control of the δ phase balances grain boundary strengthening and brittleness risk. 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. This enables the matrix structure to maintain dimensional stability and defect tolerance under high-temperature stress, thereby comprehensively improving the service performance of the material in extreme thermo-coupling environments.

[0031] (3) Beneficial technical effects

[0032] 1. This invention achieves grain refinement and dislocation density control through multi-stage rolling and segmented annealing optimization. In the initial rolling stage, high rolling force and multi-pass deformation are used to achieve grain refinement and dislocation density control. Intermediate annealing combined with argon protection and rapid air cooling suppresses coarse precipitates and retains work hardening effect. In the finishing rolling stage, low rolling force and progressive deformation combined with secondary annealing optimize grain boundary distribution. The final rolling yields ultra-thin foil with uniform microstructure. Compared with the traditional single-stage rolling process, this invention effectively solves the industry problem of coarse grains and uneven precipitate distribution in high-temperature alloy materials. It is particularly suitable for high-temperature load-bearing components such as aerospace engine blades. Through the control of rolling force gradient and precise matching of annealing parameters, a triple synergy of grain refinement, precipitate control and grain boundary strengthening is achieved, which significantly improves the high-temperature stability and creep resistance of the material.

[0033] 2. This invention utilizes rapid heating and precise temperature control under argon protection during finished product annealing, combined with gradient temperature control during solution treatment and two-stage aging phase transformation regulation. This eliminates residual rolling stress while preserving the substructure to promote uniform nucleation of the γ'' phase. Compared to traditional single-stage annealing technology, it effectively solves the industry pain points of uneven precipitate distribution and insufficient high-temperature stability in high-temperature alloy materials. It is particularly suitable for high-temperature load-bearing components such as turbine blades of aero-engines. Through the differential distribution of the γ'' phase within the grains / grain boundaries and the segregation of the δ phase grain boundaries, a multi-scale strengthening network is formed. This, along with the pinning effect of the NbC phase and the coherent strengthening of the γ' phase, achieves triple synergistic strengthening of precipitates, grain boundaries, and dislocations. The precise matching of its heat treatment parameters and rolling strain significantly improves the material's high-temperature creep resistance, providing key material support for the next generation of aerospace propulsion systems.

[0034] 3. This invention precisely controls the gradient precipitation of the γ'' phase at grain boundaries / within grains and the construction of a three-dimensional strengthening network of the δ phase through the synergistic effect of segmented temperature control during solution treatment and two-stage aging temperature sequence in multi-stage heat treatment. Compared with traditional single-stage aging technology, it effectively solves the industry bottleneck of the difficulty in balancing creep resistance and microstructural stability of high-temperature alloys. It is particularly suitable for extreme thermo-coupling components such as turbine disks of aero engines. Through the multi-phase synergistic mechanism of dislocation pinning by the coherent strain field of the γ'' phase, crack propagation inhibition by the geometric interpenetration of the δ phase, and grain coarsening inhibition by the Zener pinning of the NbC phase, combined with the optimization of the volume ratio of the γ' phase to the γ'' phase and the control of the aspect ratio of the δ phase, it achieves cross-scale matching of precipitate morphology, grain boundary structure and defect configuration. 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 next generation of high thrust-to-weight ratio aero engines. Attached Figure Description

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

[0036] Figure 2 The image shows the microstructure of the multi-stage rolled high-temperature alloy material prepared in Example 1 of this invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0038] Example 1: A method for preparing a multi-stage rolled high-temperature alloy material, comprising the following steps:

[0039] S1. Alloy ingot pretreatment: Commercial Inconel 718 alloy ingot raw material is placed in a vacuum induction melting furnace for melting, and then cast into a plate with a thickness of 2.0 mm; the melting parameters are: under a vacuum of 10⁻³ Pa, heated to 1550℃ at a heating rate of 15℃ / min, and held for 35 min.

[0040] S2. Multi-stage rolling forming: The S1 sheet is subjected to primary rolling, intermediate annealing, finishing rolling, secondary annealing, and final rolling in sequence to obtain foil. The parameters for primary rolling are: using a four-roll reversible cold rolling mill, setting the rolling force to 850 kN, rolling the 2.0 mm sheet to 0.38 mm in 6 passes, rolling speed 9 m / min, and surface roughness Ra≤0.8μm. The parameters for intermediate annealing are: under an argon protective atmosphere, the annealing temperature is 950℃, the annealing time is 10 min, and after annealing, air cooling is performed at a rate of 32℃ / s. The parameters for finishing rolling are as follows: using a 20-roll mill, rolling force of 220 kN, rolling 0.38 mm sheet to 0.26 mm in 16 passes; the parameters for secondary annealing are as follows: under an argon protective atmosphere, annealing temperature of 920℃, annealing time of 10 min, followed by air cooling at a rate of 32℃ / s; the parameters for final rolling are as follows: rolling the secondary annealed sheet to 0.06 mm foil with a thickness tolerance of ±1.5 μm.

[0041] S3. Finished product annealing: The foil material from S2 is subjected to finished product annealing to obtain annealed foil material; the parameters for finished product annealing are as follows: the final rolled foil material is placed in a tube furnace, heated to 950℃ at 35℃ / min under argon protection, held at that temperature for 12 min, and then furnace cooled to room temperature.

[0042] S4. Multi-stage heat treatment: The annealed foil of S3 is subjected to solution treatment and two-stage aging in sequence to finally obtain multi-stage rolled high-temperature alloy material; The parameters of solution treatment are: solution treatment at 900℃ for 250 min in an argon protective atmosphere, followed by raising the temperature to 965℃ at a heating rate of 20℃ / min and holding for 55 min; The parameters of two-stage aging are: first aging at 725℃ for 450 min for first-stage aging; then aging at 625℃ for 450 min for second-stage aging.

[0043] The multi-stage rolled high-temperature alloy material of this embodiment contains a γ' phase and a γ'' phase; the γ' phase and the γ'' phase are disk-shaped nano-precipitates with an average diameter of 15 nm; the volume ratio of the γ' phase and the γ'' phase is 1:2.0; the multi-stage rolled high-temperature alloy material contains a δ phase, the δ phase is needle-shaped or short rod-shaped with an average length of 200 nm; the multi-stage rolled high-temperature alloy material contains an NbC phase, the NbC phase is spherical or cubic with an average length of 52 nm; the average diameter of the multi-stage rolled high-temperature alloy material is 2.5 μm.

[0044] Figure 1 The image shows a physical picture of the multi-stage rolled high-temperature alloy material prepared in Example 1 of the present invention, proving that the high-temperature alloy foil was successfully prepared by the process method, indicating that the method is feasible in actual production. Figure 2 The microstructure of the multi-stage rolled high-temperature alloy material prepared in Example 1 is shown in the image. The material exhibits a uniform microstructure distribution, fine grains, and no significant segregation, further demonstrating that the method of this invention can optimize the alloy's microstructure and improve the material's performance stability. In summary, the multi-stage rolling and heat treatment process proposed in this invention can effectively control the microstructure of high-temperature alloy foils, achieving high uniformity, high strength, and excellent high-temperature performance, meeting the application requirements of high-temperature service environments such as aerospace.

[0045] Example 2: A method for preparing a multi-stage rolled high-temperature alloy material, comprising the following steps:

[0046] S1. Alloy ingot pretreatment: Commercial Inconel 718 alloy ingot raw material was placed in a vacuum induction melting furnace for melting, and then cast into a plate with a thickness of 2.3 mm; the melting parameters were: under a vacuum of 10⁻³ Pa, heated to 1565℃ at a heating rate of 17℃ / min, and held for 35 min.

[0047] S2. Multi-stage rolling forming: The S1 sheet is subjected to primary rolling, intermediate annealing, finishing rolling, secondary annealing, and final rolling in sequence to obtain foil. The parameters for primary rolling are: using a four-roll reversible cold rolling mill, setting the rolling force to 900 kN, rolling the 2.3 mm sheet to 0.45 mm in 7 passes, rolling speed 11 m / min, and surface roughness Ra≤0.8μm. The parameters for intermediate annealing are: under an argon protective atmosphere, the annealing temperature is 950℃, the annealing time is 10 min, and after annealing, air cooling is performed at a rate of 32℃ / s. The parameters for finishing rolling are as follows: using a 20-roll mill, rolling force of 250 kN, rolling 0.45 mm sheet to 0.28 mm in 18 passes; the parameters for secondary annealing are as follows: under an argon protective atmosphere, annealing temperature of 920℃, annealing time of 10 min, followed by air cooling at a rate of 32℃ / s; the parameters for final rolling are as follows: rolling the secondary annealed sheet to 0.07 mm foil with a thickness tolerance of ±1.5 μm.

[0048] S3. Finished product annealing: The foil from S2 is annealed to obtain annealed foil. The parameters for finished product annealing are as follows: the final rolled foil is placed in a tube furnace and heated to 950°C at 40°C / min under argon protection, held for 12 min, and then cooled to room temperature in the furnace.

[0049] S4. Multi-stage heat treatment: The annealed foil of S3 is subjected to solution treatment and two-stage aging in sequence to finally obtain multi-stage rolled high-temperature alloy material; The parameters of solution treatment are: solution treatment at 902℃ for 250 min in an argon protective atmosphere, followed by raising the temperature to 965℃ at a heating rate of 20℃ / min and holding for 55 min; The parameters of two-stage aging are: first aging at 725℃ for 450 min for first-stage aging; then aging at 625℃ for 450 min for second-stage aging.

[0050] The multi-stage rolled high-temperature alloy material of this embodiment contains a γ' phase and a γ'' phase; the γ' phase and the γ'' phase are disk-shaped nanoprecipitates with an average diameter of 16 nm; the volume ratio of the γ' phase and the γ'' phase is 1:2.3; the multi-stage rolled high-temperature alloy material contains a δ phase, the δ phase is needle-shaped or short rod-shaped with an average length of 320 nm; the multi-stage rolled high-temperature alloy material contains an NbC phase, the NbC phase is spherical or cubic with an average size of 80 nm; the average diameter of the multi-stage rolled high-temperature alloy material is 2.7 μm.

[0051] Example 3: A method for preparing a multi-stage rolled high-temperature alloy material, comprising the following steps:

[0052] S1. Alloy ingot pretreatment: Commercial Inconel 718 alloy ingot raw material was placed in a vacuum induction melting furnace for melting, and then cast into a plate with a thickness of 2.6 mm; the melting parameters were: under a vacuum of 10⁻³ Pa, heated to 1570℃ at a heating rate of 18℃ / min, and held for 38 min.

[0053] S2. Multi-stage rolling forming: The S1 sheet is subjected to primary rolling, intermediate annealing, finishing rolling, secondary annealing, and final rolling in sequence to obtain foil. The parameters for primary rolling are: using a four-roll reversible cold rolling mill, setting the rolling force to 950 kN, rolling the 2.6 mm sheet to 0.55 mm in 7 passes, rolling speed 12 m / min, and surface roughness Ra≤0.8μm. The parameters for intermediate annealing are: under an argon protective atmosphere, the annealing temperature is 952℃, the annealing time is 11 min, and after annealing, air cooling is performed at a rate of 33℃ / s. The parameters for finishing rolling are as follows: using a 20-roll mill, rolling force of 280 kN, rolling 0.55 mm sheet to 0.29 mm in 19 passes; the parameters for secondary annealing are as follows: under an argon protective atmosphere, annealing temperature of 922℃, annealing time of 11 min, followed by air cooling at a rate of 33℃ / s; the parameters for final rolling are as follows: rolling the secondary annealed sheet to 0.07 mm foil with a thickness tolerance of ±1.5 μm.

[0054] S3. Finished product annealing: The foil material from S2 is subjected to finished product annealing to obtain annealed foil material; the parameters for finished product annealing are as follows: the finished rolled foil material is placed in a tube furnace, heated to 952℃ at 45℃ / min under argon protection, held at that temperature for 13 min, and then furnace cooled to room temperature.

[0055] S4. Multi-stage heat treatment: The annealed foil of S3 is subjected to solution treatment and two-stage aging in sequence to finally obtain multi-stage rolled high-temperature alloy material; The parameters of solution treatment are: solution treatment at 903℃ for 255 min in an argon protective atmosphere, followed by raising the temperature to 968℃ at a heating rate of 20℃ / min and holding for 58 min; The parameters of two-stage aging are: first aging at 728℃ for 470 min for first-stage aging; then aging at 628℃ for 470 min for second-stage aging.

[0056] The multi-stage rolled high-temperature alloy material of this embodiment contains a γ' phase and a γ'' phase; the γ' phase and the γ'' phase are disk-shaped nanoprecipitates with an average diameter of 18 nm; the volume ratio of the γ' phase and the γ'' phase is 1:2.7; the multi-stage rolled high-temperature alloy material contains a δ phase, the δ phase is needle-shaped or short rod-shaped with an average length of 450 nm; the multi-stage rolled high-temperature alloy material contains an NbC phase, the NbC phase is spherical or cubic with a size of 160 nm; the average diameter of the multi-stage rolled high-temperature alloy material is 2.9 μm.

[0057] Example 4: A method for preparing a multi-stage rolled high-temperature alloy material, comprising the following steps:

[0058] S1. Alloy ingot pretreatment: Commercial Inconel 718 alloy ingot raw material is 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 are: under a vacuum of 10⁻³ Pa, heated to 1580℃ at a heating rate of 20℃ / min, and held for 40 min.

[0059] S2. Multi-stage rolling forming: The S1 sheet is subjected to primary rolling, intermediate annealing, finishing rolling, secondary annealing, and final rolling in sequence to obtain foil. The parameters for primary rolling are: using a four-roll reversible cold rolling mill, setting the rolling force to 980 kN, rolling the 3.0 mm sheet to 0.62 mm in 8 passes, rolling speed 12 m / min, and surface roughness Ra≤0.8μm. The parameters for intermediate annealing are: under an argon protective atmosphere, the annealing temperature is 955℃, the annealing time is 12 min, and after annealing, air cooling is performed at a rate of 35℃ / s. The parameters for finishing rolling are as follows: using a 20-roll mill, rolling force of 290 kN, rolling 0.62 mm sheet to 0.30 mm in 20 passes; the parameters for secondary annealing are as follows: under an argon protective atmosphere, annealing temperature of 925℃, annealing time of 12 min, followed by air cooling at a rate of 35℃ / s; the parameters for final rolling are as follows: rolling the secondary annealed sheet to 0.08 mm foil with a thickness tolerance of ±1.5 μm.

[0060] S3. Finished product annealing: The foil material from S2 is subjected to finished product annealing to obtain annealed foil material; the parameters for finished product annealing are as follows: the finished rolled foil material is placed in a tube furnace, heated to 955℃ at 50℃ / min under argon protection, held at that temperature for 14 min, and then furnace cooled to room temperature.

[0061] S4. Multi-stage heat treatment: The annealed foil of S3 is subjected to solution treatment and two-stage aging in sequence to finally obtain multi-stage rolled high-temperature alloy material; The parameters of solution treatment are: solution treatment at 905℃ for 260 min in an argon protective atmosphere, followed by raising the temperature to 970℃ at a heating rate of 20℃ / min and holding for 60 min; The parameters of two-stage aging are: first aging at 730℃ for 480 min for first-stage aging; then aging at 630℃ for 480 min for second-stage aging.

[0062] The multi-stage rolled high-temperature alloy material of this embodiment contains a γ' phase and a γ'' phase; the γ' phase and the γ'' phase are disk-shaped nanoprecipitates with an average diameter of 20 nm; the volume ratio of the γ' phase and the γ'' phase is 1:3.0; the multi-stage rolled high-temperature alloy material contains a δ phase, the δ phase is needle-shaped or short rod-shaped with an average length of 500 nm; the multi-stage rolled high-temperature alloy material contains an NbC phase, the NbC phase is spherical or cubic with an average size of 200 nm; the average diameter of the multi-stage rolled high-temperature alloy material is 3.0 μm.

[0063] Comparative Example 1

[0064] It is basically the same as Example 1, except that during the initial rolling process of S2, the rolling force is reduced to 600kN and the number of passes is reduced to 4.

[0065] Comparative Example 2

[0066] It is basically the same as Example 1, except that in the intermediate annealing process of S2, the annealing temperature is increased to 980°C and the annealing time is extended to 20 min.

[0067] Comparative Example 3

[0068] The process is basically the same as in Example 1, except that during the S2 finishing rolling process, the rolling speed is increased to 20 m / min and the rolling force is reduced to 150 kN.

[0069] Comparative Example 4

[0070] It is basically the same as Example 1, except that the final thickness is adjusted to 0.10 mm during the final rolling process of S2.

[0071] Comparative Example 5

[0072] The process is basically the same as in Example 1, except that during the annealing of the finished product in S3, the heating rate is reduced to 10°C / min and the holding time is extended to 30 min.

[0073] Comparative Example 6

[0074] The process is basically the same as in Example 1, except that the heat preservation temperature is reduced to 880°C and the heat preservation time is shortened to 180 min during the S4 solution treatment.

[0075] Comparative Example 7

[0076] It is basically the same as Example 1, except that in the S4 two-stage aging process, the first-stage aging temperature is increased to 750°C and the second-stage aging temperature is decreased to 600°C.

[0077] Performance testing:

[0078] High-temperature tensile property testing: The high-temperature alloy material was cut into standard tensile specimens, and tensile tests were conducted on a Gleeble thermal simulator or a high-temperature electronic universal testing machine, referring to GB / T 4338-2006 "Metallic Materials - High-Temperature Tensile Testing Method". The test temperatures were set to room temperature, 650℃, 750℃, and 850℃, and the tensile rate was set to 0.001 s⁻¹, to determine the yield strength, tensile strength, and elongation at break of the material. Through high-temperature tensile testing, the strength retention and plasticity changes of the alloy foil at different service temperatures were evaluated, providing data support for its application in high-temperature environments.

[0079] Creep performance testing: High-temperature alloy materials were cut into 10 mm × 50 mm specimens and subjected to long-term creep tests at 650℃, 700℃, and 750℃ with constant tensile stresses of 150 MPa and 200 MPa, respectively. The evolution curves of strain over time were recorded using a creep testing machine to analyze the steady-state creep rate and creep life. This experiment allows for the evaluation of the creep resistance of alloy foils under long-term high-temperature service conditions, providing reliability data for applications such as turbine blades and hot-end components of gas turbines.

[0080] High-temperature oxidation performance test: The prepared foil sample was cut into 20 mm × 20 mm pieces and subjected to isothermal oxidation test in air at 1000℃ for 50 h, 100 h and 200 h respectively. This experiment was used to evaluate the oxidation resistance of the alloy foil and to optimize the alloy composition and surface treatment process to improve the durability of the material under high-temperature conditions.

[0081] Fatigue performance testing: The high temperature low cycle fatigue (LCF) test method was adopted. Under the condition of 700℃, 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 sample was tested. This experiment can reveal the life and failure mode of the material under cyclic loading, which is of great significance for application in high temperature vibration environment (such as aero-engine blades).

[0082] The properties of the high-temperature alloy materials of Examples 1-4 and Comparative Examples 1-7 are summarized in Table 1.

[0083] Table 1 Summary of the performance of the high-temperature alloy materials in Examples 1-7 and Comparative Examples 1-7

[0084]

[0085] As shown in Table 1, different process parameters have a significant impact on the microstructure and properties of high-temperature alloys. Reducing the rolling force and the number of passes leads to insufficient deformation and decreased grain refinement, thereby reducing tensile strength, yield strength, and creep life. Simultaneously, increased microstructure inhomogeneity also reduces fatigue life, while increased precipitate size may slightly increase high-temperature oxidation weight gain. Excessively high annealing temperature and prolonged annealing time result in abnormal grain growth, reducing the material's high-temperature strength and creep life. Simultaneously, δ-phase coarsening significantly increases high-temperature oxidation weight gain, resulting in a marked decrease in fatigue life. Excessively high rolling speed and insufficient rolling force during finishing rolling cause uneven deformation, leading to decreased microstructure homogeneity and consequently reduced strength and creep life. However, fine grains may still form in localized areas, resulting in some properties falling between those of the examples and other processes. Fatigue life is slightly reduced, and high-temperature oxidation performance deteriorates slightly. Increasing the final rolling thickness affects the texture optimization effect, reducing tensile strength and yield strength. However, due to the still relatively high overall microstructure density, high-temperature oxidation performance does not change significantly, while creep life and fatigue life decrease slightly. During finished product annealing, a reduced heating rate and excessively long holding time can lead to coarsening of precipitates, resulting in decreased material strength and creep life, while maintaining good plasticity and minimal changes in high-temperature oxidation properties, although fatigue life decreases slightly. Lowering the solution temperature or shortening the holding time affects the solubility of alloying elements, inhibiting the precipitation of γ' and γ'' phases, leading to decreased high-temperature strength. Simultaneously, the NbC phase size decreases, reducing creep life, and the uneven microstructure increases high-temperature oxidation weight gain, further decreasing fatigue life. During aging, excessively high primary aging temperatures can cause γ' phase coarsening, reducing high-temperature strength, while excessively low secondary aging temperatures may inhibit precipitate formation, affecting the strength-toughness balance of the material and significantly reducing creep life. High-temperature oxidation weight gain is the greatest, while fatigue life is the lowest, and insufficient precipitation strengthening leads to the most significant decrease in crack propagation capacity. Therefore, rationally optimizing rolling, annealing, solution treatment, and aging processes can significantly improve the strength, toughness, and high-temperature stability of high-temperature alloy foils to meet the requirements of aerospace and high-temperature service environments.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any equivalent structural transformations made under the concept of the present invention and using the contents of the specification and drawings of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a multi-stage rolled high-temperature alloy material, characterized in that, Includes the following steps: S1. Alloy ingot pretreatment: Commercial Inconel 718 alloy ingots are placed in a vacuum induction melting furnace for melting, and then cast into plates with a thickness of 2.0~3.0 mm; S2. Multi-stage rolling forming: The S1 sheet is subjected to primary rolling, intermediate annealing, fine rolling, secondary annealing and final rolling in sequence to obtain foil material; S3. Finished product annealing: The foil material from S2 is subjected to finished product annealing to obtain annealed foil material; S4. Multi-stage heat treatment: The annealed foil of S3 is subjected to solution treatment and two-stage aging in sequence to finally obtain multi-stage rolled high-temperature alloy material; The parameters for the initial rolling in step S2 are as follows: using a four-roll reversible cold rolling mill, setting the rolling force to 800~1000 kN, rolling the 2.0~3.0 mm plate to 0.35~0.65 mm in 6~8 passes, rolling speed 8~12 m / min, and surface roughness Ra≤0.8μm; The parameters for the intermediate annealing in step S2 are as follows: under an argon protective atmosphere, the annealing temperature is 945~955℃, the annealing time is 8~12min, and after annealing, air cooling is performed at a rate of 30~35℃ / s. The parameters for the finishing rolling in step S2 are as follows: using a 20-roll mill, with a rolling force of 200~300 kN, the 0.35~0.45mm plate is rolled to 0.25~0.30 mm in 15~20 passes. The parameters for the secondary annealing in step S2 are as follows: under an argon protective atmosphere, the annealing temperature is 915~925℃, the annealing time is 8~12min, and after annealing, air cooling is performed at a rate of 30~35℃ / s. The parameters for the finished product annealing in step S3 are as follows: the finished rolled foil is placed in a tube furnace and heated to 945-955°C at 30-50°C / min under argon protection, held for 10-14 min and then cooled to room temperature in the furnace. The parameters for the solution treatment in step S4 are as follows: under an argon protective atmosphere, the solution treatment is carried out at 900~905℃ for 240~260 min, and then the temperature is increased to 960~970℃ at a heating rate of 20℃ / min and held for 50~60 min. The parameters for the two-stage aging process in step S4 are as follows: firstly, aging at 720~730℃ for 420~480 minutes is performed as the first-stage aging process; then, aging at 620~630℃ for 420~480 minutes is performed as the second-stage aging process.

2. The method for preparing a multi-stage rolled high-temperature alloy material as described in claim 1, characterized in that, The melting parameters for step S1 are as follows: under a vacuum of 10⁻³ Pa, heat to 1550~1580℃ at a heating rate of 15~20℃ / min, and hold for 30~40 min.

3. The method for preparing a multi-stage rolled high-temperature alloy material as described in claim 1, characterized in that, The final rolling parameters in step S2 are: rolling the annealed sheet into foil with a thickness tolerance of 0.05~0.08 mm and a thickness tolerance of ±1.5 μm.

4. A multi-stage rolled high-temperature alloy material, characterized in that, The multi-stage rolled high-temperature alloy material is prepared by any one of the preparation methods described in claims 1 to 3; The multi-stage rolled high-temperature alloy material contains a γ' phase and a γ'' phase; the γ' phase and the γ'' phase are disk-shaped nano-precipitates 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 rolled high-temperature alloy material contains a δ phase, which is needle-shaped or short rod-shaped with an average length of 200~500nm; The multi-stage rolled high-temperature alloy material contains an NbC phase, which is spherical or cubic in shape and has an average size of 50~200 nm.

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