A nickel-based superalloy ultrathin foil, a preparation method and use thereof

Abstract

The application belongs to the technical field of high-temperature alloy processing, and particularly relates to a nickel-based high-temperature alloy ultra-thin foil and a preparation method and application thereof. According to the application, the cold rolling deformation of each pass is limited to 10% to 30%, a 1050 DEG C to 1100 DEG C stress relief annealing cycle rolling mechanism is matched when the cumulative deformation reaches 65% to 70%, and a 1170 DEG C to 1230 DEG C solid solution treatment process is coupled to the 0.02 mm to 0.03 mm ultra-thin intermediate blank, so that the problems of strip breakage, poor plate shape precision, low thickness uniformity, large internal stress, insufficient room temperature and high-temperature tensile strength in the prior art can be solved, and thus the nickel-based ultra-thin foil with high mechanical properties can be stably prepared.

Description

Technical Field

[0001] This application belongs to the field of high-temperature alloy processing technology, and in particular relates to a nickel-based high-temperature alloy ultrathin foil, its preparation method, and its uses. Background Technology

[0002] Nickel-based superalloys possess excellent high-temperature mechanical properties, resistance to oxidation and corrosion, and structural stability, making them widely used in aero-engine combustion chambers, hot-end components of heavy-duty gas turbines, and high-end sealing assemblies. Ultra-thin foils with a thickness of 0.02mm to 0.03mm are core materials for sealing structures, elastic components, and thermal insulation components, and require stringent standards for thickness uniformity, surface quality, shape accuracy, room temperature tensile strength, and high-temperature tensile strength.

[0003] Existing nickel-based superalloy ultrathin foils are mainly prepared using conventional multi-pass cold rolling methods. Medium-thickness billets are used as raw materials and are directly subjected to continuous cold rolling to thin them. The deformation amount per pass is usually too large or set arbitrarily, without stable range control. When the thickness is close to the target thickness, a one-time high-temperature annealing is used for softening, without stress relief treatment at the critical nodes of cumulative deformation. The finished product only undergoes simple stress relief treatment without special solid solution strengthening treatment, and finally obtains ultrathin foils.

[0004] The above-mentioned conventional preparation methods have the following technical defects: First, the rolling stability is poor. Conventional processes lack standardized control over the deformation amount per pass, resulting in large deformation fluctuations. During the rolling process, phenomena such as strip deviation and vibration are prone to occur, making it difficult to ensure the uniformity of ultra-thin foil thickness.

[0005] Second, internal stress and sheet shape defects are severe. The rolling process does not include a segmented stress relief process, and deformation stress continues to accumulate, which can easily cause sheet shape defects such as wavy, warped, and wrinkled foil.

[0006] Third, the mechanical properties are insufficient. The finished product lacks solid solution strengthening treatment, and the distribution of carbides inside the alloy is disordered and the degree of grain refinement is limited, making it difficult to meet the requirements of high tensile strength and high-temperature service stability of ultrathin foil materials.

[0007] Fourth, weak industrialization capabilities. The process parameters are highly random, the yield is low, and the breakage rate is high during the production of ultra-thin foil, making it impossible to achieve large-scale, high-quality, and stable mass production. Summary of the Invention

[0008] This application provides a nickel-based superalloy ultrathin foil, its preparation method, and its applications to solve the following technical problem: how to stably prepare nickel-based superalloy ultrathin foil with high mechanical properties.

[0009] In a first aspect, embodiments of this application provide a method for preparing a nickel-based high-temperature alloy ultrathin foil, the method comprising: A nickel-based superalloy cold-rolled billet is subjected to multiple cold rolling passes to reduce the nickel-based cold-rolled billet to a target thickness, wherein the cold rolling deformation in each of the multiple cold rolling passes is 10% to 30%; During the multi-pass cold rolling process, when the cumulative deformation of the nickel-based high-temperature alloy cold-rolled billet reaches 65%~70%, the nickel-based high-temperature alloy cold-rolled billet is subjected to stress-relief annealing at a temperature of 1050℃~1100℃ to eliminate the internal stress of the nickel-based high-temperature alloy cold-rolled billet and restore the plasticity of the nickel-based cold-rolled billet. Repeat the multi-pass cold rolling and stress-relief annealing until the nickel-based superalloy cold-rolled billet is thinned to 0.02 mm to 0.03 mm to obtain an ultra-thin intermediate billet; The ultrathin intermediate billet is subjected to solution treatment at a temperature of 1170℃~1230℃ to fully dissolve the reinforcing phase in the ultrathin intermediate billet and homogenize the microstructure of the ultrathin intermediate billet, thereby obtaining a solution-treated billet. The solution-treated blank is then finished to obtain an ultrathin foil product. The chemical composition of the nickel-based superalloy, by mass fraction, is as follows: C: 0.05%~0.15%, Cr: 20.0%~24.0%, Fe: 17.50%~19.50%, Co: 0.50%~1.50%, Mo: 8.0%~10.0%, W: 0.2%~0.8%, B: 0.002%~0.008%, with the balance being Ni and unavoidable impurities.

[0010] Optionally, the initial thickness of the nickel-based high-temperature alloy cold-rolled billet is 4.5 mm to 4.0 mm.

[0011] Optionally, during the repeated multi-pass cold rolling and stress-relief annealing at 1050℃~1100℃, the nickel-based superalloy cold-rolled billet is successively thinned from 4.5mm~4.0mm to 1.35mm, from 1.35mm to 0.45mm, from 0.45mm to 0.15mm, from 0.15mm to 0.05mm, and from 0.05mm to 0.02mm~0.03mm.

[0012] Optionally, the holding time of the stress-relief annealing is the time required for the nickel-based superalloy cold-rolled billet to fully eliminate internal stress and restore plasticity, and the cold-rolled billet is cooled by rapid cooling after the stress-relief annealing.

[0013] Optionally, the holding time of the solution treatment is the time required for the strengthening phase in the ultrathin intermediate billet to be fully dissolved and for the microstructure of the ultrathin intermediate billet to be homogenized, and the solution-treated billet is cooled by rapid water cooling or rapid air cooling after the solution treatment.

[0014] Optionally, the stress-relief annealing temperature is 1080°C, and the solution treatment temperature is 1200°C.

[0015] Optionally, the finishing process includes surface grinding, tension straightening, cleaning, low-temperature drying, and shearing of the solution-treated blank.

[0016] Optionally, the thickness accuracy of the ultrathin foil product is ±3.0%~±5.0%, the surface roughness Ra≤0.15μm, and the yield is ≥96%.

[0017] Optionally, before performing the multi-pass cold rolling on the nickel-based superalloy cold-rolled billet, the method further includes: The nickel-based high-temperature alloy cold-rolled billet is pretreated, which includes surface inspection, grinding and welding, and ultrasonic testing to remove oxide scale, cracks and inclusions from the surface of the cold-rolled billet.

[0018] In a second aspect, embodiments of this application provide a nickel-based high-temperature alloy ultrathin foil, which is prepared by any one of the preparation methods described in the first aspect; The nickel-based high-temperature alloy ultrathin foil has a thickness of 0.02 mm to 0.03 mm, a thickness accuracy of ±3.0% to ±5.0%, and a surface roughness Ra≤0.15 μm; The nickel-based high-temperature alloy ultrathin foil has a room temperature tensile strength ≥600MPa, a yield strength ≥380MPa, an elongation ≥10%, and a high-temperature tensile strength ≥200MPa.

[0019] Thirdly, embodiments of this application provide an application for a nickel-based high-temperature alloy ultrathin foil, which is used in sealing components of aero engines or heavy-duty gas turbines.

[0020] The technical solution provided in this application has the following advantages compared with the prior art: Multi-pass cold rolling of nickel-based superalloy cold-rolled billets, with each pass's deformation controlled within 10% to 30%, ensures uniform deformation distribution during each pass, preventing stress concentration in any localized area. This prevents edge cracks, wrinkles, and even strip breakage in ultra-thin sections, thus guaranteeing rolling stability during multi-pass cold rolling.

[0021] In multi-pass cold rolling, when the cumulative deformation of the cold-rolled billet reaches 65%~70%, stress-relief annealing is performed on the cold-rolled billet at a temperature of 1050℃~1100℃. This reduces the dislocation density inside the cold-rolled billet and releases residual stress, thereby eliminating the internal stress of the cold-rolled billet and restoring its plasticity. This provides sufficient deformation capacity for subsequent cold rolling and prevents the cold-rolled billet from cracking due to plasticity depletion.

[0022] Repeated cold rolling and stress-relief annealing are performed until the cold-rolled billet is thinned to 0.02mm to 0.03mm to obtain an ultra-thin intermediate billet. This process ensures that the cold-rolled billet maintains a good shape and sufficient plasticity reserve throughout the progressive thinning process, thereby enabling the continuous production of ultra-thin intermediate billets from 4.5mm to 4.0mm billets to 0.02mm to 0.03mm billets.

[0023] Solution treatment of ultrathin intermediate billets at temperatures of 1170℃~1230℃ can fully dissolve reinforcing phases such as carbides in the ultrathin intermediate billets into the matrix and make the grain structure of the ultrathin intermediate billets tend to be homogenized. This results in a solution-treated billet with a uniform structure and fully dissolved reinforcing phases, which in turn enables the final ultrathin foil product to have both high room temperature tensile strength and high temperature tensile strength.

[0024] Finishing the solution-treated billet can remove the oxide layer and defects on the surface of the solution-treated billet and correct the shape of the billet, thereby obtaining an ultra-thin foil product with a smooth surface, straight shape and stable dimensions.

[0025] In summary, by limiting the cold rolling deformation in each pass to 10%~30%, matching the cyclic rolling mechanism of stress-relief annealing at 1050℃~1100℃ when the cumulative deformation reaches 65%~70%, and coupling the process of solution treatment at 1170℃~1230℃ for 0.02mm~0.03mm ultrathin intermediate billets, it is possible to synergistically solve the problems of easy strip breakage during rolling, poor plate shape accuracy, low thickness uniformity, high internal stress, and insufficient room temperature and high temperature tensile strength in existing technologies. This enables the stable preparation of high mechanical properties of nickel-based high-temperature alloy ultrathin foils. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings required in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other related drawings can be derived from these drawings without creative effort.

[0028] Figure 1 This is a photograph of the finished nickel-based high-temperature alloy ultrathin foil material from Example 1 of this application. Figure 2 This is a metallographic diagram of the nickel-based superalloy ultrathin foil material in Example 4 of this application; Figure 3 This is a photograph of the cold-rolled intermediate billet of the nickel-based superalloy in Comparative Example 1 of this application; Figure 4 This is a metallographic diagram of the nickel-based high-temperature alloy ultrathin foil material in Comparative Example 4 of this application. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] The range descriptions used herein, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within the range. For example, a range description of 1 to 6 or 1~6 covers all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms used herein include, but are not limited to, terms such as "include"; relational terms such as "first" and "second" are used only to distinguish different entities or steps and do not imply an actual order or relationship; and / or indicate that multiple situations may exist alone or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. Proportional relationships mentioned herein, such as mass ratios and molar ratios, should be understood as the correspondence between the antecedent and consequent terms of a proportional expression, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained through commercial purchase or prepared using existing methods.

[0031] In a first aspect, embodiments of this application provide a method for preparing a nickel-based high-temperature alloy ultrathin foil, the method comprising: A nickel-based superalloy cold-rolled billet is subjected to multiple cold rolling passes to reduce the billet to a target thickness, wherein the cold rolling deformation in each pass is 10% to 30%. During the multi-pass cold rolling process, when the cumulative deformation of the nickel-based superalloy cold-rolled billet reaches 65%~70%, the cold-rolled billet is subjected to stress-relief annealing at a temperature of 1050℃~1100℃ to eliminate the internal stress of the cold-rolled billet and restore its plasticity. Repeat the multi-pass cold rolling and stress-relief annealing until the nickel-based superalloy cold-rolled billet is thinned to 0.02 mm to 0.03 mm to obtain an ultra-thin intermediate billet; The ultrathin intermediate billet is subjected to solution treatment at a temperature of 1170℃~1230℃ to fully dissolve the reinforcing phase in the ultrathin intermediate billet and homogenize the microstructure of the ultrathin intermediate billet, thereby obtaining a solution-treated billet. The solution-treated blank is then finished to obtain an ultrathin foil product. The chemical composition of the nickel-based superalloy, by mass fraction, is as follows: C: 0.05%~0.15%, Cr: 20.0%~24.0%, Fe: 17.50%~19.50%, Co: 0.50%~1.50%, Mo: 8.0%~10.0%, W: 0.2%~0.8%, B: 0.002%~0.008%, with the balance being Ni and unavoidable impurities.

[0032] Nickel-based superalloy cold-rolled billet: In this embodiment, it refers to a nickel-based alloy cold-rolled billet. The chemical composition of the nickel-based cold-rolled billet meets the standard requirements: C: 0.05%~0.15%, Cr: 20.0%~24.0%, Fe: 17.50%~19.50%, Co: 0.50%~1.50%, Mo: 8.0%~10.0%, W: 0.2%~0.8%, B: 0.002%~0.008%, with the balance being Ni and unavoidable impurities. Furthermore, the surface of the nickel-based superalloy cold-rolled billet is free of defects such as cracks, folds, and oxide inclusions, and the thickness can be 4.5 mm. Multi-pass cold rolling: In this embodiment, it refers to using a high-precision cold rolling mill to perform continuous multi-pass cold rolling thinning operations on the nickel-based cold-rolled billet.

[0033] The inventive approach of this application compared to the prior art lies in the fact that the prior art adopts a one-time annealing softening mode with arbitrary setting of single-pass deformation amount and no cumulative deformation node control, while the solution of this application establishes a closed-loop coupling mechanism of 10%~30% cold rolling deformation amount per pass / 65%~70% cumulative deformation amount / 1050℃~1100℃ stress-relief annealing, and combines this closed-loop coupling mechanism with ultra-thin special solid solution strengthening treatment, thereby achieving the unity of stable rolling of ultra-thin foil and high-performance finished products.

[0034] The initial thickness of cold-rolled nickel-based superalloy billets includes, but is not limited to, 4.5mm, 4.3mm, 4.2mm, 4.1mm, and 4.0mm. The deformation per cold rolling pass includes, but is not limited to, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, and 30%. The cumulative deformation includes, but is not limited to, 65%, 66%, 67%, 68%, 69%, and 70%. The stress-relief annealing temperature includes, but is not limited to, 1050℃, 1060℃, 1070℃, 1080℃, 1090℃, and 1100℃. The thickness of ultra-thin intermediate billets is 0.02mm to 0.03mm, including but not limited to 0.03mm, 0.028mm, 0.025mm, 0.022mm, and 0.02mm. Solution treatment temperatures include, but are not limited to, 1170℃, 1180℃, 1190℃, 1200℃, 1210℃, 1220℃, and 1230℃.

[0035] In some embodiments, the initial thickness of the nickel-based superalloy cold-rolled billet is 4.5 mm to 4.0 mm.

[0036] In some embodiments, during the repeated multi-pass cold rolling and stress-relief annealing at 1050°C to 1100°C, the nickel-based superalloy cold-rolled billet is successively thinned from 4.5mm to 4.0mm to 1.35mm, from 1.35mm to 0.45mm, from 0.45mm to 0.15mm, from 0.15mm to 0.05mm, and from 0.05mm to 0.02mm to 0.03mm.

[0037] During the repeated multi-pass cold rolling and stress-relief annealing at 1050℃~1100℃, the nickel-based cold-rolled billet is successively thinned from 4.5mm~4.0mm to 1.35mm, from 1.35mm to 0.45mm, from 0.45mm to 0.15mm, from 0.15mm to 0.05mm, and from 0.05mm to 0.02mm~0.03mm. This step-by-step thinning path ensures that the thinning ratio of each cycle is within a controllable range. This allows each round of stress-relief annealing to fully eliminate internal stress and restore plasticity before the cold-rolled billet enters the next ultra-thin stage. This avoids edge cracking or strip breakage of the cold-rolled billet due to excessive stress accumulation at any thinning stage, thus ensuring the rolling continuity of the cold-rolled billet throughout the entire process. Consequently, it enables the stable production of high-mechanical-performance nickel-based high-temperature alloy ultra-thin foils.

[0038] The thickness variations of cold-rolled nickel-based superalloy billets include, but are not limited to, 4.5mm, 1.35mm, 0.45mm, 0.15mm, 0.05mm, 0.03mm, 0.025mm, and 0.02mm.

[0039] In some embodiments, the holding time of the stress-relief annealing is the time required for the nickel-based superalloy cold-rolled billet to fully eliminate internal stress and restore plasticity, and the cold-rolled billet is cooled by a rapid cooling method after the stress-relief annealing.

[0040] Rapid cooling method: In the embodiments of this application, it refers to the rapid furnace cooling operation performed on the cold-rolled billet of nickel-based superalloy after stress-relief annealing.

[0041] Setting the holding time for stress-relief annealing to the time required for the cold-rolled nickel-based superalloy billet to fully eliminate internal stress and restore plasticity allows the cold-rolled billet to obtain sufficient thermal activation time at a temperature of 1050℃~1100℃, thereby enabling the dislocations inside the cold-rolled billet to fully recover and the grain boundary stress to fully relax, thus allowing the internal stress of the cold-rolled billet to be fully eliminated and the plasticity to be fully restored.

[0042] Using rapid cooling after stress-relief annealing to cool the cold-rolled nickel-based superalloy billet can suppress unnecessary phase transformations or grain growth during slow cooling. This allows the cold-rolled billet to rapidly decrease to a temperature suitable for continued cold rolling while maintaining the microstructure obtained from stress-relief annealing. This shortens the process cycle and ensures the consistency of the microstructure starting point for the next cold rolling pass, thereby guaranteeing the efficiency and microstructure stability of cyclic rolling. Ultimately, this enables the stable production of ultrathin nickel-based superalloy foils with high mechanical properties.

[0043] In some embodiments, the holding time of the solution treatment is the time required for the reinforcing phase in the ultrathin intermediate billet to be fully dissolved and for the microstructure of the ultrathin intermediate billet to be homogenized, and the solution-treated billet is cooled by rapid water cooling or rapid air cooling after the solution treatment.

[0044] Rapid water cooling: In this embodiment, it refers to the operation method of immersing the solution-treated billet in water for rapid cooling after solution treatment. Rapid air cooling: In this embodiment, it refers to the operation method of placing the solution-treated billet in air for rapid cooling after solution treatment.

[0045] Setting the holding time of the solution treatment to the time required for the strengthening phase in the ultrathin intermediate billet to be fully dissolved and for the microstructure of the ultrathin intermediate billet to be homogenized allows the ultrathin intermediate billet to obtain sufficient thermal activation time at a temperature of 1170℃~1230℃. This allows the strengthening phases such as carbides in the ultrathin intermediate billet to be fully dissolved in the austenite matrix, and makes the grain size of the ultrathin intermediate billet tend to be uniform. In turn, the solution-treated billet can obtain a homogenized single-phase austenite microstructure.

[0046] After solution treatment, rapid water cooling or rapid air cooling can be used to cool the solution-treated billet, which can inhibit the re-precipitation of the strengthening phase that has been fully dissolved during the slow cooling process. This allows the strengthening phase in the solution-treated billet to remain in the matrix in a supersaturated solution state, so that it can be strengthened by precipitation during aging in subsequent use. This enables the finished ultrathin foil to obtain high room temperature tensile strength and high temperature tensile strength, and thus can stably prepare nickel-based high-temperature alloy ultrathin foil with high mechanical properties.

[0047] In some embodiments, the stress-relief annealing temperature is 1080°C, and the solution treatment temperature is 1200°C.

[0048] Setting the stress-relief annealing temperature to 1080℃, which is the midpoint of the 1050℃~1100℃ temperature range, allows the cold-rolled billet to obtain stable and sufficient thermal activation conditions during the stress-relief annealing process. This enables the dislocation recovery and stress relaxation processes inside the cold-rolled billet to proceed efficiently, thereby allowing the internal stress of the cold-rolled billet to be fully eliminated and its plasticity to be fully restored.

[0049] Setting the solution treatment temperature to 1200℃, which is the midpoint of the temperature range of 1170℃ to 1230℃, allows the ultrathin intermediate billet to obtain stable and sufficient thermal activation conditions during the solution treatment process. This enables the strengthening phase in the ultrathin intermediate billet to dissolve fully and the microstructure to become sufficiently homogenized, thereby enabling the solution-treated billet to obtain excellent microstructure and mechanical properties.

[0050] By fixing the stress-relief annealing temperature to 1080℃ and the solution treatment temperature to 1200℃, stable and repeatable process parameters can be obtained for the multi-pass cold rolling and stress-relief annealing cycle process and the solution treatment process. This ensures batch-to-batch process consistency, thereby improving the stability and yield of industrial production and enabling the stable preparation of high-mechanical-performance nickel-based superalloy ultrathin foils.

[0051] In some embodiments, the finishing process includes grinding the surface of the solution-treated billet, tension straightening, cleaning, and low-temperature drying.

[0052] Surface grinding: In this embodiment, it refers to the operation of treating the surface of the solution-treated blank by grinding with a polishing cloth. Tension straightening: In this embodiment, it refers to the operation of straightening the shape of the solution-treated blank under tension. Cleaning: In this embodiment, it refers to the operation of removing grease contamination from the surface of the solution-treated blank using a degreasing agent. Low-temperature drying: In this embodiment, it refers to the operation of drying the solution-treated blank at a low temperature to remove moisture, generally within the temperature range of room temperature to 100°C.

[0053] Surface grinding of solution-treated billets can remove the oxide layer and minor defects on the surface of the solution-treated billets, thereby giving the solution-treated billets a low surface roughness.

[0054] Tension straightening of solution-treated billets can correct plate shape defects under tension, thereby obtaining a straight plate shape for the solution-treated billets.

[0055] Cleaning the solution-treated billet can remove grease and contaminants from its surface, thus giving it a clean surface.

[0056] Low-temperature drying of solution-treated billets can remove residual moisture from their surface, thus preventing corrosion during storage and use.

[0057] By combining surface grinding, tension straightening, cleaning, and low-temperature drying, the solution-treated billet can simultaneously possess low surface roughness, a clean surface, no moisture residue, and a straight plate shape. This results in a finished ultrathin foil material with a smooth surface, straight plate shape, and stable dimensions, which can meet the stringent requirements for surface quality and dimensional accuracy of sealing components for aero-engines and heavy-duty gas turbines. This enables the stable production of high-mechanical-performance nickel-based high-temperature alloy ultrathin foil materials.

[0058] In some embodiments, the thickness accuracy of the finished ultrathin foil is ±3.0% to ±5.0%, the surface roughness Ra≤0.15μm, and the yield is ≥96%.

[0059] In some embodiments, the mechanical properties of the finished ultrathin foil include room temperature tensile strength ≥600MPa, yield strength ≥380MPa, elongation ≥10%, and high temperature tensile strength ≥200MPa.

[0060] The thickness accuracy of the ultra-thin foil finished product is ±3.0% to ±5.0%. This thickness accuracy range characterizes the thickness uniformity level of the ultra-thin foil finished product across its entire width and length. This thickness accuracy is achieved through a cyclic mechanism of stress-relief annealing at 1050℃ to 1100℃ when the deformation amount of each cold rolling pass is controlled at 10% to 30% and the cumulative deformation amount reaches 65% to 70%, as well as tension straightening in the finishing process. This enables the ultra-thin foil finished product to meet the assembly requirements of sealing components for thickness consistency.

[0061] The surface roughness Ra of the finished ultrathin foil is ≤0.15μm. This surface roughness level characterizes the smoothness of the surface of the finished ultrathin foil. This surface roughness is achieved through wet grinding and degreasing cleaning in the finishing process, so that the finished ultrathin foil can meet the airtightness requirements of sealing components for low leakage rate.

[0062] The yield of ultra-thin foil products is ≥96%. This yield level characterizes the economy and stability of industrial production. This yield is achieved by ensuring rolling continuity through a multi-pass cold rolling and stress-relief annealing cycle mechanism, as well as closed-loop control throughout the entire process, thus enabling the feasibility of large-scale production of ultra-thin foil products.

[0063] By limiting the comprehensive indicators of thickness accuracy, surface roughness Ra and yield, it is possible to ensure that the finished ultrathin foil material meets the requirements of high precision, high surface quality and high industrial stability, thereby enabling the stable preparation of nickel-based high-temperature alloy ultrathin foil materials with high mechanical properties.

[0064] The thickness accuracy of the finished ultra-thin foil includes, but is not limited to, ±3.0%, ±3.5%, ±4.0%, ±4.5%, and ±5.0%. Surface roughness Ra includes, but is not limited to, 0.15μm, 0.14μm, 0.13μm, 0.12μm, and 0.10μm. Yield includes, but is not limited to, 96%, 97%, 98%, and 99%.

[0065] In some embodiments, the method further includes, prior to performing the multi-pass cold rolling on the nickel-based cold-rolled billet: The nickel-based high-temperature alloy cold-rolled billet is pretreated, which includes surface inspection, grinding and welding, and ultrasonic testing to remove oxide scale, cracks and inclusions from the surface of the cold-rolled billet.

[0066] Cracks: In this application embodiment, cracks refer to fracture defects on or near the surface of cold-rolled billets. Inclusions: In this application embodiment, inclusions refer to non-metallic or metallic foreign objects mixed into the surface or interior of cold-rolled billets.

[0067] Before performing multiple cold rolling passes on nickel-based superalloy cold-rolled billets, surface inspection of the billets can identify defects such as cracks, folds, and oxide inclusions on the surface, thus providing a basis for defect location in subsequent grinding operations.

[0068] Grinding nickel-based superalloy cold-rolled billets can remove oxide scale, cracks, and inclusions from the surface of the billets, thereby giving the cold-rolled billets a clean and defect-free initial surface.

[0069] Ultrasonic testing of cold-rolled nickel-based superalloy billets can detect defects such as cracks, inclusions, and pores inside or near the surface of the billets. This allows for the identification of internal quality hazards that cannot be reached by surface inspection and grinding, and provides a basis for locating internal defects in subsequent grinding or removal operations.

[0070] By combining surface inspection, grinding, and ultrasonic testing as pretreatment, it can be ensured that the surface of the cold-rolled billet entering multiple cold rolling processes is free of oxide scale, cracks, inclusions, and internal defects exceeding the standard. This prevents surface and internal defects from being pressed into the interior or expanding into larger defects during subsequent multiple cold rolling processes, thus ensuring the initial quality of the multi-pass cold rolling. Consequently, it improves the overall yield and finished product quality stability, enabling the stable production of high-mechanical-performance nickel-based superalloy ultrathin foils. In a second aspect, embodiments of this application provide a nickel-based high-temperature alloy ultrathin foil, which is prepared by any one of the preparation methods described in the first aspect; The nickel-based high-temperature alloy ultrathin foil has a thickness of 0.02 mm to 0.03 mm, a thickness accuracy of ±3.0% to ±5.0%, and a surface roughness Ra≤0.15 μm.

[0071] The nickel-based superalloy ultrathin foil is prepared by any one of the preparation methods described in the first aspect. This preparation method, by limiting the cold rolling deformation in each pass to 10% to 30%, matching the stress-relief annealing cycle at 1050℃ to 1100℃ when the cumulative deformation reaches 65% to 70%, and coupling the process of solution treatment at 1170℃ to 1230℃ for 0.02mm to 0.03mm ultrathin intermediate billets, enables the nickel-based superalloy ultrathin foil to simultaneously possess high rolling stability, low internal stress, high microstructure uniformity, and high mechanical properties.

[0072] The thickness of the nickel-based superalloy ultrathin foil is 0.02mm to 0.03mm. This ultrathin thickness makes the nickel-based superalloy ultrathin foil suitable for high-end applications that require ultrathin specifications, such as sealing structures, elastic components, and thermal insulation components.

[0073] The thickness accuracy of nickel-based superalloy ultrathin foil is ±3.0% to ±5.0%, which enables it to meet the gap control requirements of precision assembly.

[0074] The surface roughness Ra of the nickel-based superalloy ultrathin foil is ≤0.15μm, which enables the nickel-based superalloy ultrathin foil to meet the airtightness requirements with low leakage rate.

[0075] By comprehensively limiting thickness, thickness accuracy, and surface roughness, it is possible to ensure that nickel-based superalloy ultrathin foils simultaneously possess ultrathin specifications, high-precision dimensions, and high surface quality, thereby meeting the stringent service conditions of sealing components for aero-engines and heavy-duty gas turbines, and thus enabling the stable production of nickel-based superalloy ultrathin foils with high mechanical properties.

[0076] Thirdly, embodiments of this application provide an application for a nickel-based high-temperature alloy ultrathin foil, which is used in sealing components of aero engines or heavy-duty gas turbines.

[0077] Sealing component: In this application embodiment, it refers to a sealing structure assembly used to prevent gas leakage.

[0078] Using the nickel-based high-temperature alloy ultrathin foil described in the second aspect for sealing components of aero engines enables the sealing components of aero engines to achieve an ultrathin specification of 0.02mm to 0.03mm, a thickness accuracy of ±3.0% to ±5.0%, and a surface roughness of Ra≤0.15μm. This results in the sealing components of aero engines possessing excellent airtightness and assembly precision, thereby reducing gas leakage from hot-end components such as the combustion chamber of aero engines, and thus improving the thermal efficiency and operational safety of aero engines.

[0079] Using the nickel-based high-temperature alloy ultrathin foil described in the second aspect for sealing components of heavy-duty gas turbines enables these components to achieve an ultrathin profile of 0.02mm to 0.03mm, a thickness accuracy of ±3.0% to ±5.0%, and a surface roughness of Ra≤0.15μm. This results in excellent airtightness and assembly precision for the sealing components, thereby reducing gas leakage from the hot-end components of the heavy-duty gas turbine and improving its thermal efficiency and operational stability.

[0080] By using nickel-based superalloy ultrathin foils in sealing components of aero engines or heavy-duty gas turbines, the high precision, high surface quality, and high mechanical properties of nickel-based superalloy ultrathin foils can be fully utilized in key sealing scenarios of high-end power equipment, thereby realizing the industrial application value of nickel-based superalloy ultrathin foils and enabling the stable preparation of nickel-based ultrathin foils with high mechanical properties.

[0081] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0082] The following are the chemical elemental compositions of the examples: The chemical elemental composition of the comparative example is uniformly adopted as follows: C: 0.08%, Cr: 22.0%, Fe: 18.50%, Co: 1.00%, Mo: 9.0%, W: 0.5%, B: 0.005%.

[0083] Example 1 A 4.5 mm thick nickel-based high-temperature alloy cold-rolled billet is pretreated. The pretreatment includes surface inspection, grinding and ultrasonic testing of the cold-rolled billet to remove oxide scale, cracks and inclusions from the surface of the cold-rolled billet.

[0084] A pretreated nickel-based superalloy cold-rolled billet is subjected to multiple cold rolling passes to reduce the cold-rolled billet to a target thickness. The cold rolling deformation of each pass is 20%, and the arrangement of the passes of the multiple cold rolling passes results in cumulative deformation of the cold-rolled billet of 70.00%, 66.67%, 66.67%, and 66.67%, respectively.

[0085] During the multi-pass cold rolling process, when the cumulative deformation of the nickel-based cold-rolled billet reaches 65%~70%, the nickel-based cold-rolled billet is subjected to stress-relief annealing at a temperature of 1080°C. The holding time of the stress-relief annealing is the time required for the nickel-based cold-rolled billet to fully eliminate internal stress and restore plasticity. After the stress-relief annealing, the nickel-based cold-rolled billet is cooled by rapid cooling to eliminate internal stress and restore plasticity.

[0086] The process of repeating the multi-pass cold rolling and stress-relief annealing is carried out. During the process of repeating the multi-pass cold rolling and stress-relief annealing, the cold-rolled billet is successively thinned from 4.5mm to 1.35mm, from 1.35mm to 0.45mm, from 0.45mm to 0.15mm, from 0.15mm to 0.05mm, and from 0.05mm to 0.03mm to obtain an ultra-thin intermediate billet.

[0087] The ultrathin intermediate billet is subjected to solution treatment at 1200°C. The holding time of the solution treatment is the time required for the reinforcing phase in the ultrathin intermediate billet to be fully dissolved and for the microstructure of the ultrathin intermediate billet to be homogenized. After the solution treatment, the solution-treated billet is cooled by rapid air cooling to fully dissolve the reinforcing phase in the ultrathin intermediate billet and to homogenize the microstructure of the ultrathin intermediate billet, thereby obtaining a solution-treated billet.

[0088] The solution-treated blank is then subjected to finishing treatment, which includes surface grinding, tension straightening, cleaning, low-temperature drying, and shearing to obtain the ultra-thin foil product.

[0089] The thickness of the finished ultra-thin foil is 0.03 mm, the thickness accuracy is ±3.0%, the surface roughness Ra is 0.15 μm, the yield is 96%, the shape is excellent, the room temperature tensile strength is 612 MPa, the yield strength is 395 MPa, the elongation is 11.5%, the high temperature tensile strength is 209 MPa, and the finished ultra-thin foil is free of cracks.

[0090] Example 2 A 4.2 mm thick nickel-based high-temperature alloy cold-rolled billet is pretreated. The pretreatment includes surface inspection, grinding and ultrasonic testing of the cold-rolled billet to remove oxide scale, cracks and inclusions from the surface of the cold-rolled billet.

[0091] A pretreated nickel-based superalloy cold-rolled billet is subjected to multiple cold rolling passes to reduce the cold-rolled billet to a target thickness. The cold rolling deformation of each pass is 25%, and the arrangement of the passes of the multiple cold rolling passes results in the cumulative deformation of the cold-rolled billet being 67.86%, 66.67%, 66.67%, and 66.67%, respectively.

[0092] During the multi-pass cold rolling process, when the cumulative deformation of the nickel-based cold-rolled billet reaches 65%~70%, the nickel-based cold-rolled billet is subjected to stress-relief annealing at a temperature of 1080°C. The holding time of the stress-relief annealing is the time required for the nickel-based cold-rolled billet to fully eliminate internal stress and restore plasticity. After the stress-relief annealing, the nickel-based cold-rolled billet is cooled by rapid cooling to eliminate internal stress and restore plasticity.

[0093] The process of repeating the multi-pass cold rolling and stress-relief annealing is carried out. During the process of repeating the multi-pass cold rolling and stress-relief annealing, the cold-rolled billet is successively thinned from 4.2 mm to 1.35 mm, from 1.35 mm to 0.45 mm, from 0.45 mm to 0.15 mm, from 0.15 mm to 0.05 mm, and from 0.05 mm to 0.03 mm to obtain an ultra-thin intermediate billet.

[0094] The ultrathin intermediate billet is subjected to solution treatment at 1170°C. The holding time of the solution treatment is the time required for the reinforcing phase in the ultrathin intermediate billet to be fully dissolved and for the microstructure of the ultrathin intermediate billet to be homogenized. After the solution treatment, the solution-treated billet is cooled by rapid water cooling in order to fully dissolve the reinforcing phase in the ultrathin intermediate billet and to homogenize the microstructure of the ultrathin intermediate billet, thereby obtaining a solution-treated billet.

[0095] The solution-treated blank is then subjected to finishing treatment, which includes surface grinding, tension straightening, cleaning, low-temperature drying, and shearing to obtain the ultra-thin foil product.

[0096] The ultra-thin foil product has a thickness of 0.03 mm, a thickness accuracy of ±3.5%, a surface roughness Ra of 0.14 μm, a yield of 97%, excellent plate shape, a room temperature tensile strength of 620 MPa, a yield strength of 390 MPa, an elongation of 12%, a high temperature tensile strength of 210 MPa, and uniform thickness. This ultra-thin foil product is suitable for high-requirement sealing components.

[0097] Example 3 A nickel-based cold-rolled billet with a thickness of 4.0 mm is pretreated. The pretreatment includes surface inspection, grinding and ultrasonic testing of the nickel-based cold-rolled billet to remove oxide scale, cracks and inclusions on the surface of the nickel-based cold-rolled billet.

[0098] The pretreated nickel-based cold-rolled billet is subjected to multiple cold rolling passes to reduce the nickel-based cold-rolled billet to a target thickness. The cold rolling deformation of each pass is 15%, and the arrangement of the passes of the multiple cold rolling passes results in the cumulative deformation of the cold-rolled billet being 66.25%, 66.67%, 66.67%, and 66.67%, respectively.

[0099] During the multi-pass cold rolling process, when the cumulative deformation of the nickel-based cold-rolled billet reaches 65%~70%, the nickel-based cold-rolled billet is subjected to stress-relief annealing at a temperature of 1080°C. The holding time of the stress-relief annealing is the time required for the nickel-based cold-rolled billet to fully eliminate internal stress and restore plasticity. After the stress-relief annealing, the nickel-based cold-rolled billet is cooled by rapid cooling to eliminate internal stress and restore plasticity.

[0100] The process of repeating the multi-pass cold rolling and stress-relief annealing is carried out. During the process of repeating the multi-pass cold rolling and stress-relief annealing, the nickel-based cold-rolled billet is successively thinned from 4.0 mm to 1.35 mm, from 1.35 mm to 0.45 mm, from 0.45 mm to 0.15 mm, from 0.15 mm to 0.05 mm, and from 0.05 mm to 0.03 mm to obtain an ultra-thin intermediate billet.

[0101] The ultrathin intermediate billet is subjected to solution treatment at 1180°C. The holding time of the solution treatment is the time required for the reinforcing phase in the ultrathin intermediate billet to be fully dissolved and for the microstructure of the ultrathin intermediate billet to be homogenized. After the solution treatment, the solution-treated billet is cooled by rapid air cooling to fully dissolve the reinforcing phase in the ultrathin intermediate billet and to homogenize the microstructure of the ultrathin intermediate billet, thereby obtaining a solution-treated billet.

[0102] The solution-treated blank is then subjected to finishing treatment, which includes surface grinding, tension straightening, cleaning, low-temperature drying, and shearing to obtain the ultra-thin foil product.

[0103] The ultra-thin foil product has a thickness of 0.03 mm, a thickness accuracy of ±4.0%, a surface roughness Ra of 0.14 μm, a yield of 96%, excellent plate shape, a room temperature tensile strength of 600 MPa, a yield strength of 380 MPa, an elongation of 10%, a high temperature tensile strength of 200 MPa, good batch consistency, and is suitable for continuous industrial production.

[0104] Example 4 A nickel-based cold-rolled billet with a thickness of 4.5 mm is pretreated. The pretreatment includes surface inspection, grinding and welding, and ultrasonic testing of the nickel-based cold-rolled billet to remove oxide scale, cracks and inclusions from the surface of the nickel-based cold-rolled billet.

[0105] The pretreated nickel-based cold-rolled billet is subjected to multiple cold rolling passes to reduce the nickel-based cold-rolled billet to a target thickness. The cold rolling deformation of each pass is 18%, and the arrangement of the passes of the multiple cold rolling passes results in the cumulative deformation of the cold-rolled billet being 70.00%, 66.67%, 66.67%, and 66.67%, respectively.

[0106] During the multi-pass cold rolling process, when the cumulative deformation of the nickel-based cold-rolled billet reaches 65%~70%, the nickel-based cold-rolled billet is subjected to stress-relief annealing at a temperature of 1050°C. The holding time of the stress-relief annealing is the time required for the nickel-based cold-rolled billet to fully eliminate internal stress and restore plasticity. After the stress-relief annealing, the nickel-based cold-rolled billet is cooled by rapid cooling to eliminate internal stress and restore plasticity.

[0107] The process of repeating the multi-pass cold rolling and stress-relief annealing is carried out. During the process of repeating the multi-pass cold rolling and stress-relief annealing, the nickel-based cold-rolled billet is successively thinned from 4.5 mm to 1.35 mm, from 1.35 mm to 0.45 mm, from 0.45 mm to 0.15 mm, from 0.15 mm to 0.05 mm, and from 0.05 mm to 0.02 mm to obtain an ultra-thin intermediate billet.

[0108] The ultrathin intermediate billet is subjected to solution treatment at 1210°C. The holding time of the solution treatment is the time required for the reinforcing phase in the ultrathin intermediate billet to be fully dissolved and for the microstructure of the ultrathin intermediate billet to be homogenized. After the solution treatment, the solution-treated billet is cooled by rapid water cooling in order to fully dissolve the reinforcing phase in the ultrathin intermediate billet and to homogenize the microstructure of the ultrathin intermediate billet, thereby obtaining a solution-treated billet.

[0109] The solution-treated blank is then subjected to finishing treatment, which includes surface grinding, tension straightening, cleaning, low-temperature drying, and shearing to obtain the ultra-thin foil product.

[0110] The thickness of the finished ultra-thin foil is 0.02 mm, the thickness accuracy is ±3.0%, the surface roughness Ra is 0.15 μm, the yield is 96%, the shape is excellent, the room temperature tensile strength is 610 MPa, the yield strength is 385 MPa, the elongation is 11%, the high temperature tensile strength is 205 MPa, and the finished ultra-thin foil is free of cracks.

[0111] Example 5 A nickel-based cold-rolled billet with a thickness of 4.2 mm is pretreated. The pretreatment includes surface inspection, grinding and welding, and ultrasonic testing of the nickel-based cold-rolled billet to remove oxide scale, cracks and inclusions from the surface of the nickel-based cold-rolled billet.

[0112] The pretreated nickel-based cold-rolled billet is subjected to multiple cold rolling passes to reduce the nickel-based cold-rolled billet to a target thickness. The cold rolling deformation of each pass is 22%, and the arrangement of the passes of the multiple cold rolling passes results in the cumulative deformation of the cold-rolled billet being 67.86%, 66.67%, 66.67%, and 66.67%, respectively.

[0113] During the multi-pass cold rolling process, when the cumulative deformation of the nickel-based cold-rolled billet reaches 65%~70%, the nickel-based cold-rolled billet is subjected to stress-relief annealing at 1100℃. The holding time of the stress-relief annealing is the time required for the nickel-based cold-rolled billet to fully eliminate internal stress and restore plasticity. After the stress-relief annealing, the nickel-based cold-rolled billet is cooled by rapid cooling to eliminate internal stress and restore plasticity.

[0114] The process of repeating the multi-pass cold rolling and stress-relief annealing is carried out. During the process of repeating the multi-pass cold rolling and stress-relief annealing, the nickel-based cold-rolled billet is successively thinned from 4.2 mm to 1.35 mm, from 1.35 mm to 0.45 mm, from 0.45 mm to 0.15 mm, from 0.15 mm to 0.05 mm, and from 0.05 mm to 0.03 mm to obtain an ultra-thin intermediate billet.

[0115] The ultrathin intermediate billet is subjected to solution treatment at 1190°C. The holding time of the solution treatment is the time required for the reinforcing phase in the ultrathin intermediate billet to be fully dissolved and for the microstructure of the ultrathin intermediate billet to be homogenized. After the solution treatment, the solution-treated billet is cooled by rapid air cooling to fully dissolve the reinforcing phase in the ultrathin intermediate billet and to homogenize the microstructure of the ultrathin intermediate billet, thereby obtaining a solution-treated billet.

[0116] The solution-treated blank is then subjected to finishing treatment, which includes surface grinding, tension straightening, cleaning, low-temperature drying, and shearing to obtain the ultra-thin foil product.

[0117] The thickness of the ultra-thin foil product is 0.03 mm, the thickness accuracy is ±3.0%, the surface roughness Ra is 0.13 μm, the yield is 97%, the shape is excellent, the room temperature tensile strength is 605 MPa, the yield strength is 382 MPa, the elongation is 10%, the high temperature tensile strength is 202 MPa, and the ultra-thin foil product is free of cracks.

[0118] Example 6 A nickel-based cold-rolled billet with a thickness of 4.5 mm is pretreated. The pretreatment includes surface inspection, grinding and welding, and ultrasonic testing of the nickel-based cold-rolled billet to remove oxide scale, cracks and inclusions from the surface of the nickel-based cold-rolled billet.

[0119] The pretreated nickel-based cold-rolled billet is subjected to multiple cold rolling passes to reduce the nickel-based cold-rolled billet to a target thickness. The cold rolling deformation of each pass is 12%, and the arrangement of the passes of the multiple cold rolling passes results in the cumulative deformation of the cold-rolled billet being 70.00%, 66.67%, 66.67%, and 66.67%, respectively.

[0120] During the multi-pass cold rolling process, when the cumulative deformation of the nickel-based cold-rolled billet reaches 65%~70%, the nickel-based cold-rolled billet is subjected to stress-relief annealing at a temperature of 1080°C. The holding time of the stress-relief annealing is the time required for the nickel-based cold-rolled billet to fully eliminate internal stress and restore plasticity. After the stress-relief annealing, the nickel-based cold-rolled billet is cooled by rapid cooling to eliminate internal stress and restore plasticity.

[0121] The process of repeating the multi-pass cold rolling and stress-relief annealing is carried out. During the process of repeating the multi-pass cold rolling and stress-relief annealing, the nickel-based cold-rolled billet is successively thinned from 4.5 mm to 1.35 mm, from 1.35 mm to 0.45 mm, from 0.45 mm to 0.15 mm, from 0.15 mm to 0.05 mm, and from 0.05 mm to 0.025 mm to obtain an ultra-thin intermediate billet.

[0122] The ultrathin intermediate billet is subjected to solution treatment at 1210°C. The holding time of the solution treatment is the time required for the reinforcing phase in the ultrathin intermediate billet to be fully dissolved and for the microstructure of the ultrathin intermediate billet to be homogenized. After the solution treatment, the solution-treated billet is cooled by rapid water cooling in order to fully dissolve the reinforcing phase in the ultrathin intermediate billet and to homogenize the microstructure of the ultrathin intermediate billet, thereby obtaining a solution-treated billet.

[0123] The solution-treated blank is then subjected to finishing treatment, which includes surface grinding, tension straightening, cleaning, low-temperature drying, and shearing to obtain the ultra-thin foil product.

[0124] The thickness of the finished ultra-thin foil is 0.025 mm, the thickness accuracy is ±3.0%, the surface roughness Ra is 0.15 μm, the yield is 96%, the shape is excellent, the room temperature tensile strength is 615 MPa, the yield strength is 388 MPa, the elongation is 11%, the high temperature tensile strength is 208 MPa, and the finished ultra-thin foil is free of cracks.

[0125] Comparative Example 1 A nickel-based cold-rolled billet with a thickness of 4.5 mm is pretreated. The pretreatment includes surface inspection, grinding and welding, and ultrasonic testing of the nickel-based cold-rolled billet to remove oxide scale, cracks and inclusions from the surface of the nickel-based cold-rolled billet.

[0126] The pretreated nickel-based cold-rolled billet is subjected to multiple cold rolling passes to directly and continuously cold roll the nickel-based cold-rolled billet from 4.5 mm to 0.03 mm, wherein stress-relief annealing is not performed during the multiple cold rolling process.

[0127] The nickel-based cold-rolled billet experienced multiple strip breaks during rolling, had extremely poor sheet shape, high internal stress, and severe cracking, making it impossible to produce qualified nickel-based cold-rolled billets.

[0128] The yield rate of the ultra-thin foil product is 50%, the thickness accuracy of the ultra-thin foil product is ±10.0%, the surface roughness Ra of the ultra-thin foil product is 0.25μm, the room temperature tensile strength of the ultra-thin foil product is 450MPa, the yield strength of the ultra-thin foil product is 280MPa, the elongation of the ultra-thin foil product is 5%, and the high temperature tensile strength of the ultra-thin foil product is 150MPa.

[0129] Comparative Example 2 A nickel-based cold-rolled billet with a thickness of 4.5 mm is pretreated. The pretreatment includes surface inspection, grinding and welding, and ultrasonic testing of the nickel-based cold-rolled billet to remove oxide scale, cracks and inclusions from the surface of the nickel-based cold-rolled billet.

[0130] The pretreated nickel-based cold-rolled billet is subjected to multiple cold rolling passes to reduce the nickel-based cold-rolled billet to a target thickness. The cold rolling deformation of each pass is 20%, and the arrangement of the passes of the multiple cold rolling passes results in the cumulative deformation of the cold-rolled billet being 70.00%, 66.67%, 66.67%, and 66.67%, respectively.

[0131] During the multi-pass cold rolling process, when the cumulative deformation of the nickel-based cold-rolled billet reaches 65%~70%, the nickel-based cold-rolled billet is subjected to stress-relief annealing at a temperature of 1080°C. The holding time of the stress-relief annealing is the time required for the nickel-based cold-rolled billet to fully eliminate internal stress and restore plasticity. After the stress-relief annealing, the nickel-based cold-rolled billet is cooled by rapid cooling to eliminate internal stress and restore plasticity.

[0132] The process of repeating the multi-pass cold rolling and stress-relief annealing is carried out. During the process of repeating the multi-pass cold rolling and stress-relief annealing, the nickel-based cold-rolled billet is successively thinned from 4.5 mm to 1.35 mm, from 1.35 mm to 0.45 mm, from 0.45 mm to 0.15 mm, from 0.15 mm to 0.05 mm, and from 0.05 mm to 0.03 mm to obtain an ultra-thin intermediate billet.

[0133] The ultrathin intermediate billet is not subjected to solution treatment, but only to stress relief treatment.

[0134] The ultra-thin intermediate blank that has undergone stress relief treatment is subjected to finishing treatment, which includes surface grinding, tension straightening, cleaning, low-temperature drying and shearing to obtain the finished ultra-thin foil material.

[0135] The thickness of the ultra-thin foil product is 0.03 mm, the thickness accuracy is ±8.0%, the surface roughness Ra is 0.20 μm, the yield is 70%, the shape is poor, the room temperature tensile strength is 705 MPa, the yield strength is 412 MPa, the elongation is 2.1%, the high temperature tensile strength is 252 MPa, the microstructure is uneven, and the ultra-thin foil product cannot meet the requirements for gas turbine sealing.

[0136] Comparative Example 3 A nickel-based cold-rolled billet with a thickness of 4.5 mm is pretreated. The pretreatment includes surface inspection, grinding and welding, and ultrasonic testing of the nickel-based cold-rolled billet to remove oxide scale, cracks and inclusions from the surface of the nickel-based cold-rolled billet.

[0137] The pretreated nickel-based cold-rolled billet is subjected to multiple cold rolling passes to reduce the nickel-based cold-rolled billet to a target thickness. The cold rolling deformation of each pass is 35%, and the arrangement of the passes of the multiple cold rolling passes results in the cumulative deformation of the cold-rolled billet being 70.00%, 66.67%, 66.67%, and 66.67%, respectively.

[0138] During the multi-pass cold rolling process, when the cumulative deformation of the nickel-based cold-rolled billet reaches 65%~70%, the nickel-based cold-rolled billet is subjected to stress-relief annealing at a temperature of 1080°C. The holding time of the stress-relief annealing is the time required for the nickel-based cold-rolled billet to fully eliminate internal stress and restore plasticity. After the stress-relief annealing, the nickel-based cold-rolled billet is cooled by rapid cooling to eliminate internal stress and restore plasticity.

[0139] During the repeated multi-pass cold rolling and stress-relief annealing process, the nickel-based cold-rolled billet experienced strip breakage when it was thinned from 0.45 mm to 0.15 mm, making it impossible to continue rolling.

[0140] The nickel-based cold-rolled billet cannot be rolled to the target thickness, and the nickel-based cold-rolled billet cannot be used to obtain an ultra-thin intermediate billet.

[0141] Comparative Example 4 A nickel-based cold-rolled billet with a thickness of 4.5 mm is pretreated. The pretreatment includes surface inspection, grinding and welding, and ultrasonic testing of the nickel-based cold-rolled billet to remove oxide scale, cracks and inclusions from the surface of the nickel-based cold-rolled billet.

[0142] The pretreated nickel-based cold-rolled billet is subjected to multiple cold rolling passes to reduce the nickel-based cold-rolled billet to a target thickness. The cold rolling deformation of each pass is 20%, and the arrangement of the passes of the multiple cold rolling passes results in the cumulative deformation of the cold-rolled billet being 70.00%, 66.67%, 66.67%, and 66.67%, respectively.

[0143] During the multi-pass cold rolling process, when the cumulative deformation of the nickel-based cold-rolled billet reaches 65%~70%, the nickel-based cold-rolled billet is subjected to stress-relief annealing at 1150°C. The holding time of the stress-relief annealing is the time required for the nickel-based cold-rolled billet to fully eliminate internal stress and restore plasticity. After the stress-relief annealing, the nickel-based cold-rolled billet is cooled by rapid cooling.

[0144] The process of repeating the multi-pass cold rolling and stress-relief annealing is carried out. During the process of repeating the multi-pass cold rolling and stress-relief annealing, the nickel-based cold-rolled billet is successively thinned from 4.5 mm to 1.35 mm, from 1.35 mm to 0.45 mm, from 0.45 mm to 0.15 mm, from 0.15 mm to 0.05 mm, and from 0.05 mm to 0.03 mm to obtain an ultra-thin intermediate billet.

[0145] The ultrathin intermediate billet is subjected to solution treatment at 1200°C. The holding time of the solution treatment is the time required for the reinforcing phase in the ultrathin intermediate billet to be fully dissolved and for the microstructure of the ultrathin intermediate billet to be homogenized. After the solution treatment, the ultrathin intermediate billet is cooled by rapid air cooling in order to fully dissolve the reinforcing phase in the ultrathin intermediate billet and to homogenize the microstructure of the ultrathin intermediate billet, thereby obtaining a solution-treated billet.

[0146] The solution-treated blank is then subjected to finishing treatment, which includes surface grinding, tension straightening, cleaning, low-temperature drying, and shearing to obtain the ultra-thin foil product.

[0147] The thickness of the finished ultra-thin foil is 0.03 mm, the thickness accuracy is ±5.0%, the surface roughness Ra is 0.18 μm, the yield is 80%, the finished ultra-thin foil has poor shape, the room temperature tensile strength is 520 MPa, the yield strength is 320 MPa, the elongation is 7%, the high temperature tensile strength is 170 MPa, the grains are coarse, the stress-relief annealing temperature of 1150℃ is too high, resulting in multiple rounds of recrystallization and grain growth accumulation during cyclic rolling, ultimately causing coarsening of the grains in the ultra-thin intermediate billet; the subsequent 1200℃ solution treatment can only homogenize the microstructure and cannot refine the already coarse grains, ultimately resulting in coarse grains and overall deterioration of the mechanical properties of the finished product.

[0148] The microstructure of the finished ultrathin foil material is coarse.

[0149] Comparative Example 5 A nickel-based cold-rolled billet with a thickness of 4.5 mm is pretreated. The pretreatment includes surface inspection, grinding and welding, and ultrasonic testing of the nickel-based cold-rolled billet to remove oxide scale, cracks and inclusions from the surface of the nickel-based cold-rolled billet.

[0150] The pretreated nickel-based cold-rolled billet is subjected to multiple cold rolling passes to reduce the nickel-based cold-rolled billet to a target thickness. The cold rolling deformation of each pass is 20%, and the arrangement of the passes of the multiple cold rolling passes results in the cumulative deformation of the cold-rolled billet being 70.00%, 66.67%, 66.67%, and 66.67%, respectively.

[0151] During the multi-pass cold rolling process, when the cumulative deformation of the nickel-based cold-rolled billet reaches 65%~70%, the nickel-based cold-rolled billet is subjected to stress-relief annealing at a temperature of 1080°C. The holding time of the stress-relief annealing is the time required for the nickel-based cold-rolled billet to fully eliminate internal stress and restore plasticity. After the stress-relief annealing, the nickel-based cold-rolled billet is cooled by rapid cooling to eliminate internal stress and restore plasticity.

[0152] The process of repeating the multi-pass cold rolling and stress-relief annealing is carried out. During the process of repeating the multi-pass cold rolling and stress-relief annealing, the nickel-based cold-rolled billet is successively thinned from 4.5 mm to 1.35 mm, from 1.35 mm to 0.45 mm, from 0.45 mm to 0.15 mm, from 0.15 mm to 0.05 mm, and from 0.05 mm to 0.03 mm to obtain an ultra-thin intermediate billet.

[0153] The ultrathin intermediate billet is subjected to solution treatment at 1100°C. The holding time of the solution treatment is the time required for the strengthening phase in the ultrathin intermediate billet to be fully dissolved and for the microstructure of the ultrathin intermediate billet to be homogenized. After the solution treatment, the solution-treated billet is cooled by rapid air cooling.

[0154] The solution-treated blank is then subjected to finishing treatment, which includes surface grinding, tension straightening, cleaning, low-temperature drying, and shearing to obtain the ultra-thin foil product.

[0155] The thickness of the finished ultra-thin foil is 0.03 mm, the thickness accuracy is ±5.0%, the surface roughness Ra is 0.18 μm, the yield is 80%, the finished ultra-thin foil has poor shape, the room temperature tensile strength is 500 MPa, the yield strength is 310 MPa, the elongation is 6%, the high temperature tensile strength is 165 MPa, the reinforcing phase is not fully dissolved, and the microstructure is uneven.

[0156] Comparative Example 6 A nickel-based cold-rolled billet with a thickness of 4.5 mm is subjected to multiple cold rolling passes without pretreatment to reduce the billet to the target thickness. The cold rolling deformation of each pass is 20%, and the arrangement of the passes results in cumulative deformation of the cold-rolled billet of 70.00%, 66.67%, 66.67%, and 66.67%, respectively.

[0157] During the multi-pass cold rolling process, when the cumulative deformation of the nickel-based cold-rolled billet reaches 65%~70%, the nickel-based cold-rolled billet is subjected to stress-relief annealing at a temperature of 1080°C. The holding time of the stress-relief annealing is the time required for the nickel-based cold-rolled billet to fully eliminate internal stress and restore plasticity. After the stress-relief annealing, the nickel-based cold-rolled billet is cooled by rapid cooling to eliminate internal stress and restore plasticity.

[0158] The process of repeating the multi-pass cold rolling and stress-relief annealing is carried out. During the process of repeating the multi-pass cold rolling and stress-relief annealing, the nickel-based cold-rolled billet is successively thinned from 4.5 mm to 1.35 mm, from 1.35 mm to 0.45 mm, from 0.45 mm to 0.15 mm, from 0.15 mm to 0.05 mm, and from 0.05 mm to 0.03 mm to obtain an ultra-thin intermediate billet.

[0159] The ultrathin intermediate billet is subjected to solution treatment at 1180°C. The holding time of the solution treatment is the time required for the reinforcing phase in the ultrathin intermediate billet to be fully dissolved and for the microstructure of the ultrathin intermediate billet to be homogenized. After the solution treatment, the solution-treated billet is cooled by rapid air cooling to fully dissolve the reinforcing phase in the ultrathin intermediate billet and to homogenize the microstructure of the ultrathin intermediate billet, thereby obtaining a solution-treated billet.

[0160] The solution-treated blank is then subjected to finishing treatment, which includes surface grinding, tension straightening, cleaning, low-temperature drying, and shearing to obtain the ultra-thin foil product.

[0161] The thickness of the finished ultra-thin foil is 0.03 mm, the thickness accuracy is ±4.0%, the surface roughness Ra is 0.18 μm, the yield is 85%, the shape is generally good, the room temperature tensile strength is 550 MPa, the yield strength is 340 MPa, the elongation is 8%, the high temperature tensile strength is 180 MPa, and the surface of the finished ultra-thin foil has indentation defects.

[0162] Experimental methods for evaluating results: Thickness measurement method: Use a micrometer or laser thickness gauge to measure the thickness of the ultra-thin foil product at multiple points, take the arithmetic mean as the thickness measurement value, and calculate the percentage of the maximum deviation to the target thickness as the thickness accuracy.

[0163] Surface roughness Ra measurement method: The surface of the finished ultra-thin foil is scanned and measured using a stylus-type surface roughness measuring instrument or an optical profilometer, and the surface roughness Ra value is calculated according to the arithmetic mean deviation formula.

[0164] The yield measurement method is as follows: Weigh the finished product of qualified ultra-thin foil and the weight of the nickel-based cold-rolled billet. Calculate the yield by dividing the finished product of qualified ultra-thin foil by the weight of the nickel-based cold-rolled billet and multiplying by 100%.

[0165] Panel shape evaluation method: Visual inspection or ruler application method is used to check the panel shape of the finished ultra-thin foil material and observe whether there are panel shape defects such as waves, warping, central waves, and edge waves.

[0166] Room temperature tensile strength measurement method: In accordance with the standard for tensile testing of metallic materials, standard tensile specimens are prepared for ultra-thin foil products at room temperature, and tensile tests are performed using a universal testing machine to record the tensile strength value.

[0167] High-temperature tensile strength measurement method: In accordance with the standard for high-temperature tensile testing of metallic materials, standard tensile specimens are prepared for ultra-thin foil products under high-temperature conditions. Tensile tests are conducted using a high-temperature universal testing machine, and the tensile strength values ​​are recorded.

[0168] Microstructure evaluation method: Metallographic microstructure of finished or intermediate ultrathin foil materials is observed using a metallographic microscope or scanning electron microscope to evaluate the uniformity of grain size, distribution of strengthening phases and presence of abnormal structures.

[0169] Crack inspection methods: Visual inspection or penetrant testing is used to inspect the surface cracks of ultra-thin foil products or nickel-based cold-rolled billets.

[0170] Method for recording strip breakage: Record the pass location and thickness stage where strip breakage occurs in nickel-based cold-rolled billets during multi-pass cold rolling.

[0171] Internal stress evaluation method: X-ray diffraction or blind hole method is used to measure the residual stress of ultrathin foil finished products or nickel-based cold-rolled billets.

[0172] Surface defect inspection method: Visual inspection or microscopic observation is used to inspect the surface of the finished ultra-thin foil for indentation defects.

[0173] Table 1. Results of Examples / Comparative Examples As shown by the examples and comparative effect data, the technical advancements of this application's technical solution include: The yield rate has increased from 50% to 96%~97%, eliminating strip breakage; the thickness accuracy has improved from ±10.0% to ±3.0%~±4.0%, and the plate shape has improved from very poor to excellent; the room temperature tensile strength has increased from 450MPa to 600MPa~620MPa, the yield strength has increased from 280MPa to 380MPa~390MPa, the elongation has increased from 5% to 10%~12%, and the high temperature tensile strength has increased from 150MPa to 200MPa~210MPa, meeting the requirements for gas turbine sealing; the surface roughness Ra has decreased from 0.25μm to 0.15μm, with no surface indentation defects; the microstructure has changed from uneven / coarse to uniform; and the closed-loop control of the entire process ensures excellent batch consistency, making it suitable for continuous large-scale production.

[0174] Detailed explanation of the attached diagram: Figure 1 This is a finished product image of the nickel-based high-temperature alloy ultrathin foil from Embodiment 1 of this application; Figure 2 This is a metallographic diagram of the nickel-based superalloy ultrathin foil material in Example 4 of this application; Figure 3 This is a finished product image of the nickel-based high-temperature alloy ultrathin foil in Comparative Example 1 of this application; Figure 4 This is a metallographic diagram of the nickel-based superalloy ultrathin foil material in Comparative Example 4 of this application. It can be clearly seen from the diagram that: Figure 1 In Example 1, the ultrathin foil product is in the form of a regular strip roll with a smooth and flat surface, without obvious defects such as waves, warping, or edge waviness. The edges are neat and without cracks, indicating that when the cold rolling deformation is controlled at 10%~30% in each pass and the cumulative deformation reaches 65%~70%, the cyclic rolling mechanism of stress-relief annealing at 1050℃~1100℃ can effectively ensure the rolling stability and shape accuracy of the ultrathin section.

[0175] Figure 2 In Example 4, the metallographic structure of the ultrathin foil material obtained showed a uniform and fine equiaxed grain distribution, clear grain boundaries and high grain size consistency, with no obvious coarse grains or abnormal precipitates. This indicates that the solution treatment at 1170℃~1230℃ can fully dissolve the strengthening phase in the ultrathin intermediate billet and homogenize the structure, thereby obtaining an excellent microstructure.

[0176] Figure 3 In the comparison example 1, the ultrathin foil product exhibited severe bending deformation, extremely poor plate shape, obvious cracks and wrinkles at the edges, and could not form a regular strip roll. This indicates that under the continuous cold rolling mode with arbitrary setting of single-pass deformation amount and no stress relief annealing at cumulative deformation nodes, the nickel-based cold-rolled billet suffered multiple strip breaks and severe plate shape deterioration due to excessive internal stress accumulation and plasticity depletion, and could not be produced in good condition.

[0177] Figure 4In Comparative Example 4, the microstructure of the ultrathin foil exhibits a mixed-crystal state with significantly uneven grain size, locally containing obvious coarse grains and disordered grain boundary distribution. This indicates that after the stress-relief annealing temperature of 1150℃ deviated from the preferred range of 1050℃~1100℃, the accumulated heat history during subsequent cyclic rolling led to abnormal grain growth, and the 1200℃ solution treatment failed to effectively eliminate this microstructure inhomogeneity, ultimately resulting in a decrease in the room temperature strength of the finished product. The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing an ultrathin nickel-based superalloy foil, characterized in that, The method includes: A nickel-based superalloy cold-rolled billet is subjected to multiple cold rolling passes to reduce the billet to a target thickness, wherein the cold rolling deformation in each pass is 10% to 30%. During the multi-pass cold rolling process, when the cumulative deformation of the nickel-based high-temperature alloy cold-rolled billet reaches 65%~70%, the nickel-based high-temperature alloy cold-rolled billet is subjected to stress-relief annealing at a temperature of 1050℃~1100℃ to eliminate the internal stress of the nickel-based high-temperature alloy cold-rolled billet and restore the plasticity of the nickel-based high-temperature alloy cold-rolled billet. Repeat the multi-pass cold rolling and stress-relief annealing until the nickel-based superalloy cold-rolled billet is thinned to 0.02 mm to 0.03 mm to obtain an ultra-thin intermediate billet; The ultrathin intermediate billet is subjected to solution treatment at a temperature of 1170℃~1230℃ to fully dissolve the reinforcing phase in the ultrathin intermediate billet and homogenize the microstructure of the ultrathin intermediate billet, thereby obtaining a solution-treated billet. The solution-treated blank is then finished to obtain an ultrathin foil product. The chemical composition of the nickel-based superalloy, by mass fraction, is as follows: C: 0.05%~0.15%, Cr: 20.0%~24.0%, Fe: 17.50%~19.50%, Co: 0.50%~1.50%, Mo: 8.0%~10.0%, W: 0.2%~0.8%, B: 0.002%~0.008%, with the balance being Ni and unavoidable impurities.

2. The preparation method according to claim 1, characterized in that, The initial thickness of the nickel-based high-temperature alloy cold-rolled billet is 4.5 mm to 4.0 mm.

3. The preparation method according to claim 1, characterized in that, During the repeated multi-pass cold rolling and stress-relief annealing at 1050℃~1100℃, the nickel-based superalloy cold-rolled billet is successively thinned from 4.5mm~4.0mm to 1.35mm, from 1.35mm to 0.45mm, from 0.45mm to 0.15mm, from 0.15mm to 0.05mm, and from 0.05mm to 0.02mm~0.03mm.

4. The preparation method according to claim 1, characterized in that, The holding time for stress-relief annealing is the time required for the nickel-based cold-rolled billet to fully eliminate internal stress and restore plasticity, and the nickel-based cold-rolled billet is cooled by rapid cooling after stress-relief annealing.

5. The preparation method according to claim 1, characterized in that, The heat treatment holding time is the time required for the strengthening phase in the ultrathin intermediate billet to be fully dissolved and for the microstructure of the ultrathin intermediate billet to be homogenized. After the solution treatment, the solution-treated billet is cooled by rapid water cooling or rapid air cooling.

6. The preparation method according to claim 1, characterized in that, The stress-relief annealing temperature is 1080℃, and the solution treatment temperature is 1200℃.

7. The preparation method according to claim 1, characterized in that, The thickness accuracy of the ultra-thin foil finished product is ±3.0%~±5.0%, the surface roughness Ra≤0.15μm, and the yield is ≥96%.

8. The preparation method according to claim 1, characterized in that, Before performing the multi-pass cold rolling on the nickel-based superalloy cold-rolled billet, the method further includes: The nickel-based high-temperature alloy cold-rolled billet is pretreated, which includes surface inspection, grinding and welding, and ultrasonic testing to remove oxide scale, cracks and inclusions from the surface of the cold-rolled billet.

9. A nickel-based high-temperature alloy ultrathin foil, characterized in that, The nickel-based high-temperature alloy ultrathin foil is prepared by the preparation method described in any one of claims 1 to 8; The nickel-based high-temperature alloy ultrathin foil has a thickness of 0.02 mm to 0.03 mm, a thickness accuracy of ±3.0% to ±5.0%, and a surface roughness Ra≤0.15 μm; The nickel-based high-temperature alloy ultrathin foil has a room temperature tensile strength ≥600MPa, a yield strength ≥380MPa, an elongation ≥10%, and a high-temperature tensile strength ≥200MPa.

10. An application of a nickel-based high-temperature alloy ultrathin foil, characterized in that, The nickel-based high-temperature alloy ultrathin foil as described in claim 9 is used in sealing components of aero engines or heavy-duty gas turbines.

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