A method for homogenizing heat treatment of a nickel-based superalloy ingot

Abstract

The disclosure provides a nickel-based superalloy ingot homogenization heat treatment method, by establishing a standardized radial organization gradient quantitative characterization system, and innovatively introducing an organization gradient coefficient as a process decision basis, the precise diagnosis and dynamic processing of the ingot non-uniformity are realized. Based on the quantitative analysis results, the method intelligently matches the differentiated temperature-time parameters, and applies the corresponding heat treatment system to different degrees of non-uniformity and element segregation conditions, thereby effectively eliminating the radial γ' phase size distribution difference and MC carbide composition gradient of the ingot at the root. This processing mode significantly improves the overall uniformity of the ingot organization, ensures the homogeneity and stability of the material composition and microstructure, and lays a solid material foundation for the smooth implementation of the subsequent hot working process and the excellent and consistent high temperature performance of the final product.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy processing technology, and in particular to a method for homogenizing heat treatment of nickel-based high-temperature alloy ingots. Background Technology

[0002] Nickel-based superalloys are widely used in high-end equipment manufacturing due to their excellent high-temperature strength, creep resistance, and corrosion resistance. As the initial form of superalloy materials, the microstructure uniformity of the ingot directly affects the performance of subsequent processing techniques and the quality of the final product. During the solidification process of nickel-based superalloy ingots, the cooling rate varies gradient from the edge to the center, resulting in significant differences in the distribution of alloying elements and the characteristics of precipitated phases in the radial direction. This radial microstructure inhomogeneity is mainly manifested in the following ways: the size and density of the γ′ phase gradually increase from the edge to the center; the morphology, distribution, and chemical composition of MC-type carbides exhibit obvious gradient characteristics in the radial direction; and, in particular, the content ratios of easily segregating elements such as Nb and Ti in MC carbides vary significantly at different radial positions.

[0003] Currently, industrial homogenization treatment of high-temperature alloy ingots often employs fixed temperature-time process parameters. These parameters are typically set based on historical experience and lack specific consideration for the microstructure gradient characteristics of individual ingots. This "one-size-fits-all" approach has significant limitations: for ingots with small microstructure gradients, it may lead to overtreatment, resulting in coarse grains and energy waste; for ingots with large microstructure gradients, it may lead to undertreatment, failing to effectively eliminate compositional segregation and microstructure inhomogeneity.

[0004] Existing detection methods are mostly limited to metallographic observation at a single location, making it difficult to comprehensively quantify and characterize the radial microstructure gradient of ingots. Although some studies have attempted to analyze through multi-point sampling, the lack of standardized sampling specifications and unified quantitative evaluation indicators makes it impossible to provide a reliable basis for the precise optimization of homogenization processes.

[0005] Therefore, developing a method that can accurately quantify the radial microstructure gradient characteristics of ingots and dynamically adjust homogenization process parameters accordingly is of great significance for improving the microstructure uniformity of high-temperature alloy ingots, optimizing heat treatment process efficiency, and enhancing the overall performance of materials. Summary of the Invention

[0006] A first aspect of this disclosure provides a method for homogenizing heat treatment of nickel-based superalloy ingots, comprising the following steps: In the radial direction of the ingot cross section, samples were taken at three locations: 1 / 4R, 1 / 2R, and 3 / 4R. The average size and area fraction of the γ′ phase at each sampling location were statistically analyzed using an optical microscope, and the morphology and distribution characteristics of the MC carbides at each sampling location were observed using a scanning electron microscope. The content ratios of Ti, Nb, and Ta elements in MC carbides at each sampling location were determined using energy dispersive spectroscopy. Based on the obtained data, the tissue gradient coefficient K was calculated. The formula for calculating K is: K = |X 1 / 4R – X 3 / 4R | / X 1 / 2R Where X is a selected microstructure parameter, which is selected from the average size of the γ′ phase, the area fraction of the γ′ phase, or the content ratio of Nb to Ti in the MC carbide; Based on the calculated tissue gradient coefficient K value, the corresponding homogenization heat treatment is dynamically selected and executed, specifically including: when K < 0.1, holding at 1200℃ for 24 hours; when 0.1 ≤ K < 0.3, holding at 1150℃ for 12 hours, then gradually increasing the temperature to 1210℃ and holding for 15 hours; when K ≥ 0.3, holding at 1180℃ for 8 hours, then increasing the temperature to 1220℃ and holding for 20 hours, followed by slow cooling.

[0007] In conjunction with the first aspect, the standardization of sampling at three positions—1 / 4R, 1 / 2R, and 3 / 4R—in the radial direction of the ingot cross-section is as follows: on two mutually perpendicular diameters passing through the center of the ingot, samples are taken at 1 / 4, 1 / 2, and 3 / 4 of each radius, for a total of four positions. The sample data at the same radius position are then combined and calculated to finally obtain the microstructure parameter values ​​at the 1 / 4R, 1 / 2R, and 3 / 4R positions.

[0008] In conjunction with the first aspect, the average size and area fraction of the γ′ phase are quantitatively statistically analyzed using image analysis software.

[0009] In conjunction with the first aspect, when calculating the tissue gradient coefficient K, the average size of the γ′ phase, the area fraction of the γ′ phase, and the ratio of Nb to Ti content in the MC carbide are used as the tissue parameter X to calculate three corresponding tissue gradient coefficient K values. The maximum value among the three calculated K values ​​is used as the criterion for judgment.

[0010] In conjunction with the first aspect, when K ≥ 0.3, if the ratio of Nb to Ti content in the MC carbide at the 3 / 4R position is found to be greater than 1.5 times the ratio of Nb to Ti content in the MC carbide at the 1 / 2R position, then the holding time at 1220℃ should be extended by an additional 10 to 15 hours.

[0011] In conjunction with the first aspect, the slow cooling treatment specifically includes controlling the ingot to cool to 900°C at a cooling rate of no more than 10°C / min, followed by air cooling.

[0012] In conjunction with the first aspect, after processing, the radial microstructure uniformity of the ingot satisfies at least one of the following conditions: The average size difference of the γ′ phase at the 1 / 4R, 1 / 2R, and 3 / 4R positions of the ingot does not exceed 5%; The range of Nb to Ti content ratio in the MC carbides at positions 1 / 4R, 1 / 2R, and 3 / 4R of the ingot is less than 10%.

[0013] A second aspect of this disclosure provides an electronic device, comprising: One or more processors; A storage unit is used to store one or more programs that, when executed by one or more processors, enable the one or more processors to implement the homogenization heat treatment method for nickel-based superalloy ingots.

[0014] A third aspect of this disclosure provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, enables the homogenization heat treatment method for nickel-based superalloy ingots.

[0015] Beneficial Effects: This disclosure provides a homogenization heat treatment method for nickel-based superalloy ingots. By establishing a standardized radial microstructure gradient quantitative characterization system and innovatively introducing a microstructure gradient coefficient as a process decision basis, it achieves accurate diagnosis and dynamic treatment of ingot inhomogeneity. Based on quantitative analysis results, this method intelligently matches differentiated temperature-time parameters and applies corresponding heat treatment regimes to different degrees of inhomogeneity and elemental segregation, thereby effectively eliminating the radial γ′ phase size distribution differences and MC carbide composition gradients in the ingot at their root. This treatment significantly improves the overall microstructure homogeneity of the ingot, ensuring the homogeneity and stability of material composition and microstructure, laying a solid material foundation for the smooth implementation of subsequent hot working processes and the achievement of excellent and consistent high-temperature performance in the final product. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of a homogenization heat treatment method for nickel-based superalloy ingots according to an embodiment of the present disclosure. Figure 2 This is a schematic diagram of the sampling location of the ingot cross-section according to an embodiment of the present disclosure; Figure 3 This is a 1 / 4R position optical microscope tissue image of an embodiment of this disclosure; Figure 4 This is a 1 / 2R position optical microscope tissue image of an embodiment of this disclosure; Figure 5 This is a 3 / 4R position optical microscope tissue image of an embodiment of this disclosure; Figure 6 The morphology of MC carbides at the 1 / 4R position in this embodiment of the present disclosure is shown under a scanning electron microscope. Figure 7The morphology of MC carbides at the 1 / 2R position in this embodiment of the present disclosure is shown under a scanning electron microscope. Figure 8 The morphology of MC carbides at the 3 / 4R position in this embodiment of the present disclosure is shown under a scanning electron microscope. Figure 9 An electronic device according to an embodiment of this disclosure. Detailed Implementation

[0017] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those disclosed herein.

[0018] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0019] Figure 1 This is a schematic flowchart of a homogenization heat treatment method for nickel-based superalloy ingots according to an embodiment of the present disclosure, including: S1: Samples were taken at three locations, 1 / 4R, 1 / 2R, and 3 / 4R, in the radial direction of the ingot cross section. The average size and area fraction of the γ′ phase at each sampling location were statistically analyzed using an optical microscope. The morphology and distribution characteristics of the MC carbides at each sampling location were observed using a scanning electron microscope. Furthermore, the sampling at three positions (1 / 4R, 1 / 2R, and 3 / 4R) in the radius direction of the ingot cross-section is standardized. Specifically, samples are taken at 1 / 4, 1 / 2, and 3 / 4 of the radius on two mutually perpendicular diameters passing through the center of the ingot, obtaining samples at four positions in total. The sample data at the same radius position are then combined and calculated to finally obtain the microstructure parameter values ​​at the 1 / 4R, 1 / 2R, and 3 / 4R positions.

[0020] The average size and area fraction of the γ′ phase were quantitatively analyzed using image analysis software.

[0021] This step is fundamental to the testing and data collection of the method, and its core lies in standardization and quantification.

[0022] Standardized sampling clearly specifies sampling at three characteristic locations (1 / 4R, 1 / 2R, 3 / 4R) along the radial direction of the ingot cross-section. This abandons the traditional practice of arbitrary sampling and ensures the comparability and repeatability of data obtained from different batches and by different inspectors, which is a prerequisite for subsequent mathematical calculations and scientific decision-making.

[0023] Multimodal analysis combines optical microscopy and scanning electron microscopy. Optical microscopy is mainly used to statistically analyze the macroscopic distribution characteristics (size and fraction) of the γ′ phase, while scanning electron microscopy, with its higher resolution, is used to observe the morphology and distribution of finer MC carbides. This combined technique provides a comprehensive characterization of the ingot's microstructure.

[0024] The cross-sampling method, which samples from four radii and then combines the results for calculation, is an optimization measure to enhance the representativeness and stability of the data. It effectively reduces random errors caused by the possible circumferential inhomogeneity of the ingot, making the microstructure parameter values ​​at the 1 / 4R, 1 / 2R, and 3 / 4R positions more accurately reflect the radial gradient of the entire cross-section.

[0025] Image analysis software and quantitative statistics upgrade the traditional, subjective "metallographic observation" to objective and precise "image analysis," eliminating the bias of human subjective judgment and making the size and area fraction of the γ′ phase reliable quantitative data, laying a solid foundation for subsequent mathematical calculations.

[0026] S2: The content ratios of Ti, Nb, and Ta elements in the MC carbides at each sampling location were determined using an energy dispersive spectroscopy (EDS) instrument. Based on the obtained data, the tissue gradient coefficient K was calculated. The formula for calculating the K value is: K = |X 1 / 4R – X 3 / 4R | / X 1 / 2R , where X 1 / 4R For tissue parameters of 1 / 4R, X 3 / 4R For tissue parameters of 3 / 4R, X 1 / 2R Tissue parameters for 1 / 2R; Furthermore, when calculating the tissue gradient coefficient K, the average size of the γ′ phase, the area fraction of the γ′ phase, and the ratio of Nb to Ti content in the MC carbide are used as the tissue parameter X to calculate three corresponding tissue gradient coefficient K values. The maximum value among the three calculated K values ​​is used as the criterion for judgment.

[0027] Energy dispersive spectroscopy (EDS) compositional analysis: This method delves deeper into the analysis from "morphology" to "composition," paying particular attention to the content ratios of key alloying elements such as Ti and Nb in MC carbides. This is because elemental segregation is one of the fundamental causes of microstructure inhomogeneity, and compositional gradients are a more fundamental characterization than morphological gradients.

[0028] The formula for the gradient coefficient K captures the maximum gradient difference from the edge to the near-center region; the denominator is normalized as a benchmark, eliminating the influence of absolute values ​​caused by differences in the overall size of the ingot or the base plate. This makes the K value a universally applicable, dimensionless, and comparable indicator for measuring the degree of inhomogeneity between different ingots.

[0029] The principle of maximizing multiple parameters is adopted. The γ′ phase size, area fraction, and MC carbide composition reflect the microstructure from different physical perspectives (geometric characteristics, number density, and chemical segregation). The maximum value of all three is calculated simultaneously and used as the final criterion to ensure that the selected process is sufficient to cope with the most severe inhomogeneities, effectively avoiding misjudgments and insufficient treatment caused by the "good performance" of a single parameter.

[0030] S3: Based on the calculated tissue gradient coefficient K value, dynamically select and execute the corresponding homogenization heat treatment, specifically including: when K<0.1, hold at 1200℃ for 24 hours; when 0.1 ≤ K<0.3, first hold at 1150℃ for 12 hours, then gradually increase the temperature to 1210℃ and hold for 15 hours; when K ≥ 0.3, first hold at 1180℃ for 8 hours, then increase the temperature to 1220℃ and hold for 20 hours, followed by slow cooling treatment.

[0031] Furthermore, when K ≥ 0.3, if the ratio of Nb to Ti content in the MC carbide at the 3 / 4R position is found to be greater than 1.5 times that in the MC carbide at the 1 / 2R position, the holding time at 1220℃ should be extended by an additional 10 to 15 hours.

[0032] The slow cooling process specifically includes controlling the ingot to cool to 900°C at a cooling rate of no more than 10°C / minute, followed by air cooling.

[0033] The radial microstructure uniformity of the ingot after treatment satisfies at least one of the following conditions: The average size difference of the γ′ phase at the 1 / 4R, 1 / 2R, and 3 / 4R positions of the ingot does not exceed 5%; The range of Nb to Ti content ratio in the MC carbides at positions 1 / 4R, 1 / 2R, and 3 / 4R of the ingot is less than 10%.

[0034] A clear and quantifiable decision tree is established based on the dynamic selection of the K value. According to the different threshold ranges of the K value (K<0.1, 0.1≤K<0.3, K≥0.3), different intensities and processing logics are automatically matched, which ensures the processing effect while avoiding "over-processing" of already relatively uniform ingots and energy waste.

[0035] When severe Nb enrichment (abnormally high Nb / Ti ratio) is detected at the 3 / 4R position, an additional high-temperature holding time is required, even with the general process of K≥0.3. This demonstrates the method's targeted ability to solve the common and highly detrimental problem of local segregation in high-temperature alloys, ensuring the full dissolution and diffusion of stubborn segregation bands.

[0036] The purpose of specifying a slow cooling rate of ≤10℃ / minute is to control the solid-state phase transformation and structural stress during the cooling process, and to prevent the generation of new microstructure inhomogeneities (such as secondary precipitation) or large internal stresses due to excessively rapid cooling, thereby "locking in" the homogenization effect and ensuring material properties.

[0037] For example, in combination Figure 2-8 , Metallographic samples were prepared from three locations (1 / 4R, 1 / 2R, and 3 / 4R) of an HT700P nickel-based superalloy ingot, standardized along its cross-sectional radius. The average size and area fraction of the γ′ phase at each location were statistically analyzed using an optical microscope. The morphology distribution of MC carbides was observed using a scanning electron microscope, and the elemental ratios of Ti, Nb, and Ta in the MC carbides were determined using energy dispersive spectroscopy. Specific data are shown in Table 1.

[0038] Table 1. Results of tissue parameter detection in Example 1

[0039] Using the average size of the γ′ phase as the tissue parameter X, calculate the gradient coefficient K: K = |0.8 - 1.5| / 1.2 = 0.7 / 1.2 ≈ 0.58 Since K≥0.3, and the Nb / Ti ratio (1.8) in the MC carbide at the 3 / 4R position is 1.5 times greater than the ratio (1.0) at the 1 / 2R position, the enhanced segmented heat preservation process is adopted.

[0040] Heat treatment stage: The homogenization process was performed as follows: the temperature was held at 1180℃ for 8 hours, then raised to 1220℃ and held for 30 hours (an additional 10 hours were added due to Nb segregation), and finally cooled slowly to 900℃ at a rate of ≤10℃ / min and then air-cooled.

[0041] Effect verification: After treatment, the average size difference of the γ′ phase at each location was 3.2%, and the range of Nb / Ti ratio in MC carbides was 7.5%, both of which were better than the control targets.

[0042] Electronic device 900 can be a desktop computer, laptop, handheld computer, cloud server, or other electronic device. Electronic device 900 may include, but is not limited to, a processor 901 and a memory 902. Those skilled in the art will understand that... Figure 9 This is merely an example of electronic device 900 and does not constitute a limitation on electronic device 900. It may include more or fewer components than shown, or combine certain components, or different components. For example, electronic device may also include input / output devices, network access devices, buses, etc.

[0043] The processor 901 can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0044] The memory 902 can be an internal storage unit of the electronic device 900, such as a hard disk or RAM of the electronic device 900. The memory 902 can also be an external storage device of the electronic device 900, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the electronic device 900. Furthermore, the memory 902 can include both internal and external storage units of the electronic device 900. The memory 902 is used to store the computer program 903 and other programs and data required by the electronic device. The memory 902 can also be used to temporarily store data that has been output or will be output.

[0045] In the embodiments provided in this disclosure, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. Multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0046] If an integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program may include computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. A computer-readable medium may include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in a computer-readable medium may be appropriately added to or subtracted according to the requirements of legislation and patent practice in a jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media may not include electrical carrier signals and telecommunication signals.

[0047] The above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit it. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure, and should all be included within the protection scope of this disclosure.

Claims

1. A method for homogenizing heat treatment of nickel-based superalloy ingots, characterized in that, Includes the following steps: Sampling was performed at three locations: 1 / 4R, 1 / 2R, and 3 / 4R, in the radial direction of the ingot cross section. The average size and area fraction of the γ′ phase at each sampling location were statistically analyzed using an optical microscope, and the morphology and distribution characteristics of the MC carbides at each sampling location were observed using a scanning electron microscope. The content ratios of Ti, Nb, and Ta elements in MC carbides at each sampling location were determined using energy dispersive spectroscopy. Based on the obtained data, the tissue gradient coefficient K was calculated. The formula for calculating K is: K = |X 1 / 4R – X 3 / 4R | / X 1 / 2R , where X 1 / 4R For tissue parameters of 1 / 4R, X 3 / 4R For tissue parameters of 3 / 4R, X 1 / 2R Tissue parameters for 1 / 2R; Based on the calculated tissue gradient coefficient K value, the corresponding homogenization heat treatment is dynamically selected and executed, specifically including: when K < 0.1, holding at 1200℃ for 24 hours; when 0.1 ≤ K < 0.3, holding at 1150℃ for 12 hours, then gradually increasing the temperature to 1210℃ and holding for 15 hours; when K ≥ 0.3, holding at 1180℃ for 8 hours, then increasing the temperature to 1220℃ and holding for 20 hours, followed by slow cooling.

2. The method according to claim 1, characterized in that, The standardization of sampling at three positions (1 / 4R, 1 / 2R, and 3 / 4R) in the radial direction of the ingot cross-section is as follows: on two mutually perpendicular diameters passing through the center of the ingot, samples are taken at 1 / 4, 1 / 2, and 3 / 4 of each radius, for a total of four positions. The sample data at the same radius position are then combined and calculated to obtain the final microstructure parameter values ​​at the 1 / 4R, 1 / 2R, and 3 / 4R positions.

3. The method according to claim 1, characterized in that, The average size and area fraction of the γ′ phase were quantitatively analyzed using image analysis software.

4. The method according to claim 1, characterized in that, When calculating the tissue gradient coefficient K, the average size of the γ′ phase, the area fraction of the γ′ phase, and the ratio of Nb to Ti content in the MC carbide are used as the tissue parameter X to calculate three corresponding tissue gradient coefficient K values. The maximum value among the three calculated K values ​​is used as the criterion for judgment.

5. The method according to claim 1, characterized in that, When K ≥ 0.3, if the ratio of Nb to Ti in the MC carbide at the 3 / 4R position is found to be more than 1.5 times that in the MC carbide at the 1 / 2R position, the holding time at 1220℃ should be extended by an additional 10 to 15 hours.

6. The method according to claim 1, characterized in that, The slow cooling process specifically includes controlling the ingot to cool to 900°C at a cooling rate of no more than 10°C / minute, followed by air cooling.

7. The method according to claim 1, characterized in that, The radial microstructure uniformity of the ingot after treatment satisfies at least one of the following conditions: The average size difference of the γ′ phase at the 1 / 4R, 1 / 2R, and 3 / 4R positions of the ingot does not exceed 5%; The range of Nb to Ti content ratio in the MC carbides at positions 1 / 4R, 1 / 2R, and 3 / 4R of the ingot is less than 10%.

8. A nickel-based superalloy ingot, characterized in that, The ingot is processed using the method described in any one of claims 1 to 7.

9. An electronic device, characterized in that, include: One or more processors; A storage unit for storing one or more programs that, when executed by one or more processors, enable the one or more processors to implement the homogenization heat treatment method for nickel-based superalloy ingots according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it can implement the homogenization heat treatment method for nickel-based superalloy ingots according to any one of claims 1 to 7.

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