A rapid non-destructive characterization method of nickel-based superalloys

Abstract

A rapid non-destructive characterization method of nickel-based superalloy, comprising the following steps: providing a standard sample, heat treating under a calibration parameter; non-destructively testing the standard sample to characterize a plurality of performance parameters thereof, and establishing a correspondence between the plurality of performance parameters and the calibration parameter; non-destructively testing a nickel-based superalloy sample, and inversely calculating the heat treatment temperature and heat treatment duration corresponding to a characterization result of the nickel-based superalloy sample according to the correspondence between the performance parameter and the calibration parameter. The method establishes a unique correspondence between the heat treatment parameter and the plurality of performance parameters by virtue of the inconsistency of the change trend of different performance parameters of the nickel-based superalloy with the heat treatment evolution process, so as to realize rapid characterization of the nickel-based superalloy structure.

Description

Technical Field

[0001] This invention belongs to the field of materials characterization, and specifically relates to a rapid and non-destructive characterization method for nickel-based superalloys. Background Technology

[0002] Nickel-based superalloys possess excellent high-temperature mechanical properties and are therefore widely used in the manufacture of aero-engine components. Most nickel-based superalloys are heat-treatable, requiring different heat treatment processes to form reinforcing phases such as γ', γ”, or δ in their γ matrix to enhance their performance. Researching and developing heat treatment regimes for nickel-based superalloys to obtain the desired microstructure is a crucial task in the development of nickel-based superalloy manufacturing processes. Currently, scanning electron microscopy (SEM) or transmission electron microscopy (TEM) are commonly used to directly observe the microstructure of nickel-based superalloys treated with different process parameters to determine the impact of different heat treatment processes on the microstructure. This process requires destructive sampling methods to prepare a large number of nickel-based superalloy samples, which is time-consuming, costly, and involves complex characterization processes. This prolongs the optimization process of nickel-based superalloy heat treatment parameters, increases process development costs, and cannot meet the increasingly complex and diverse process development requirements of aero-engines. Therefore, providing a rapid and non-destructive characterization method for nickel-based superalloys is of great value for optimizing the development cycle and cost of nickel-based superalloy processes. Summary of the Invention

[0003] The purpose of this invention is to provide a rapid non-destructive characterization method for nickel-based superalloys, which determines the heat treatment parameters experienced by the nickel-based superalloys through non-destructive testing.

[0004] According to an embodiment of the present invention, a rapid non-destructive characterization method for nickel-based superalloys is provided. The method includes the following steps: providing multiple standard samples of nickel-based superalloys, wherein the standard samples are heat-treated under multiple calibration parameters, the calibration parameters including heat treatment temperature and heat treatment duration; characterizing the performance parameters of the standard samples using non-destructive testing, the performance parameters including at least one of electrical conductivity, Hall coefficient, and hardness; establishing a correspondence between the calibration parameters and the performance parameters; providing a nickel-based superalloy sample to be characterized, and characterizing the performance parameters of the nickel-based superalloy sample using non-destructive testing; and determining the heat treatment temperature and heat treatment duration corresponding to the nickel-based superalloy sample based on the correspondence between the calibration parameters and the performance parameters.

[0005] During heat treatment, the changes in single performance parameters of nickel-based superalloys, such as hardness and electrical conductivity, with heat treatment temperature or time are not monotonically related. For example, before peak aging, the hardness of nickel-based superalloys increases with increasing heat treatment temperature, but after peak aging, the hardness decreases with increasing temperature. However, the evolution patterns of different performance parameters are not the same. Coupled with electrical conductivity or Hall coefficient and hardness, a correlation between heat treatment parameters and the microstructure and properties of nickel-based superalloys can be established. Using this correlation, the heat treatment process experienced by the nickel-based superalloy can be determined through inversion based on the performance parameters, thus achieving effective characterization of nickel-based superalloys without microstructural analysis.

[0006] Furthermore, in some embodiments, the method further includes a step of correcting the characterization results based on the structure and surface condition of the nickel-based superalloy sample. Nickel-based superalloy samples, such as blades, have complex surface structures and different surface conditions, which can lead to errors in the measurement results, requiring correction to compensate for these errors.

[0007] Furthermore, in some embodiments, the hardness testing method includes ultrasonic hardness testing or Vickers hardness testing.

[0008] Furthermore, in some embodiments, the heat treatment temperatures of the multiple calibration parameters used for the standard sample include: under-aging temperature, peak aging temperature, and over-aging temperature, and multiple intermediate test temperatures are also provided between the under-aging temperature and the peak aging temperature, and between the peak aging temperature and the over-aging temperature.

[0009] Furthermore, in some embodiments, the heat treatment temperatures of the plurality of calibration parameters are arranged in an arithmetic sequence with a tolerance of 30℃-50℃.

[0010] Furthermore, in some embodiments, the heat treatment duration for the plurality of calibration parameters is 1h-100h.

[0011] Furthermore, in some embodiments, the heat treatment durations of the plurality of calibration parameters are in a geometric sequence with a common ratio of 1.5-2.5.

[0012] Furthermore, in some embodiments, before characterizing the performance parameters of the standard sample, a step of grinding and polishing the standard sample is included.

[0013] Furthermore, in some embodiments, when characterizing the performance parameters, the measurement position is at least 3 mm away from the edge of the standard sample or nickel-based superalloy sample.

[0014] Furthermore, in some embodiments, when characterizing the performance parameters, there are no fewer than 10 detection points on each standard sample or nickel-based superalloy sample. Attached Figure Description

[0015] Figure 1 This is a hardness-conductivity relationship graph of a standard sample in one embodiment;

[0016] Figure 2 This is an isothermal transformation diagram of GH4169 nickel-based superalloy in one embodiment.

[0017] The purpose of the above figures is to provide a detailed description of the invention so that those skilled in the art can understand the technical concept of the invention, and not to limit the invention. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0019] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment herein. The phrase appearing in various places in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive, independent, or alternative embodiments. Those skilled in the art will understand that the embodiments herein can be combined with other embodiments without structural conflict. In the description herein, "a plurality of" means at least two.

[0020] Nickel-based superalloys are widely used in critical aerospace components. Nickel and chromium are the main elements that enhance the corrosion resistance of the alloys. In some grades of nickel-based superalloys, niobium is added to form a γ” precipitate phase, which is a metastable intermetallic compound with a tetragonal structure. The γ” precipitate phase increases hardness during aging. Titanium and aluminum form a γ' [Ni3(Ti,Al), cubic structure] precipitate phase, which is less effective than γ” in promoting alloy hardening. Another orthorhombic δ phase precipitate has no significant effect on mechanical properties; in fact, an excess can degrade performance. During short-term treatment at 700–800°C (6–8 h), both γ' and γ” phases precipitate uniformly in the matrix. If the temperature is maintained at around 800–900°C for a slightly longer period, rapid precipitation of the δ phase is observed, typically with nucleation at grain boundaries. Therefore, the performance of nickel-based superalloy parts is closely related to their thermal history. Different heat treatment parameters will significantly affect the microstructure of nickel-based superalloys and have a significant impact on their room temperature mechanical properties, high temperature strength, creep resistance, and fatigue performance.

[0021] For a given nickel-based superalloy sample, microstructural analysis is typically required to determine its thermal history. Microstructural characterization involves cutting samples from the specimen, followed by polishing and etching, and then characterizing the phase distribution within the alloy sample using scanning electron microscopy (SEM) or transmission electron microscopy (TEM). This characterization process is inherently destructive, and both sample preparation and characterization must be performed in specialized laboratories, resulting in high efficiency and cost. This leads to prolonged cycles and increased costs in optimizing the heat treatment processes for nickel-based superalloys, failing to adequately meet the increasingly diverse design requirements of aero-engine components.

[0022] To address the aforementioned problems, one embodiment of the present invention provides a rapid, non-destructive characterization method for nickel-based superalloys. This method includes the following steps:

[0023] Using GH4169 alloy as the characterization object, 49 sets of standard GH4169 alloy samples (S1-S49) were prepared. Each set included at least 3 samples, and each standard sample was 10mm × 20mm × 20mm in size. Two of the 20mm × 20mm surfaces were polished for subsequent characterization. The standard samples were fully annealed in a vacuum furnace and then aged under vacuum conditions with different calibration parameters. The calibration parameters included different aging temperatures and aging durations, as shown in Table 1.

[0024]

[0025] Table 1. Comparison of Standard Samples and Calibration Parameters

[0026] The calibration parameters are set according to the following standards: The peak aging temperature of GH4169 (720℃), a typical under-aging temperature (600℃), and a typical over-aging temperature (840℃) are selected. Two intermediate test temperatures are inserted between the under-aging temperature and the peak aging temperature, and between the peak aging temperature and the over-aging temperature, so that all test temperatures are distributed in an arithmetic sequence with a tolerance of 40℃. In other embodiments, more intermediate test temperatures can be set, with a preferred tolerance of 30℃-50℃. (The last sentence appears to be incomplete and possibly refers to a different implementation.) Figure 2 The solid-state phase transformation law reflected by the TTT curve (isothermal transformation curve) of the GH4169 alloy is shown. The typical heat treatment time range (1-100h) of the GH4169 alloy is selected, and seven heat treatment times (including the endpoints of 1h and 100h) are set according to a geometric series, with a common ratio of 2.15. In other embodiments, more calibration temperatures can be set, and the common ratio of the geometric series is preferably 1.5-2.5.

[0027] After aging treatment, non-destructive testing was performed on the standard samples to characterize their hardness and electrical conductivity. The results are as follows: Figure 1The curves showing the relationship between hardness, electrical conductivity, and calibration parameters are presented. (Based on the TTT curves and measurement results, it can be seen that the aging temperature has a more significant impact on the performance of the GH4169 alloy, while the aging time has a relatively low impact on the alloy's performance within the 1h-100h time range.) Specifically, in some embodiments, the hardness can be tested using an ultrasonic hardness tester or a Vickers hardness tester.

[0028] Before reaching peak aging, the hardness of GH4169 alloy increases with increasing temperature and aging time, but decreases with increasing temperature and aging time after entering the over-aging stage. Similarly, the electrical conductivity of GH4169 also increases with temperature and aging time before reaching the peak value of a heat treatment, but decreases with increasing temperature and aging time after exceeding the peak value. Therefore, characterizing hardness or electrical conductivity alone cannot determine the heat treatment process experienced by GH4169, nor can it predict the microstructure of the alloy. However, the trends of hardness and electrical conductivity changes with heat treatment parameters are not identical. Therefore, coupling hardness and electrical conductivity values ​​allows for the deduction of a unique heat treatment state. Furthermore, by using phase diagrams and metallographic spectra of nickel-based alloys, the microstructure of the material can be determined, thereby predicting the macroscopic properties of the sample.

[0029] A GH4169 nickel-based superalloy sample to be characterized is provided, such as a nickel-based superalloy blade or a nickel-based superalloy bladed disk. The hardness and electrical conductivity of the alloy sample are tested using the same characterization methods. For alloy samples with complex curved surfaces, such as nickel-based superalloy blades, in a preferred embodiment, the characterization results need to be corrected according to their surface structure to improve the detection accuracy.

[0030] After measuring the hardness and conductivity of the alloy blades or bladed disks, according to... Figure 1 The hardness-conductivity and calibration parameters curves shown are used for inversion calculations to determine the aging temperature and aging treatment time corresponding to the alloy blades or bladed disks.

[0031] like Figure 1 As shown, based on the different aging temperatures in the calibration parameters, the calibration data points are divided into 7 clusters. Among them, the standard samples in clusters 1, 6, and 7 are more sensitive to the aging time, and the data points are arranged in an approximately linear fashion. Based on the measurement results of the alloy samples, compared with... Figure 1 By comparing the results, the corresponding cluster is identified, and the aging temperature of the alloy blade or bladed disk is determined. When the measurement results fall into cluster 1, cluster 6, or cluster 7, the aging duration has a more significant impact on the performance parameters, and the aging temperature can be determined based on the measurement results. Figure 1 The aging time for the alloy blades or bladed disks is then determined based on the distribution of cluster data points, using the standard sample and the standard sample. For example, when the measurement results are in... Figure 1 The position in the middle is close to S1 in cluster 1, which determines its effective duration to be approximately 1 hour; when the measurement results are in Figure 1 The position of the sample is close to S49 in cluster 7, which indicates that its aging time is approximately 100 hours. Since the effect of aging time on the microstructure evolution of the GH4169 alloy is relatively weak, when the measurement results are within... Figure 1 When the alloy blades or bladed disks fall into clusters 2-5, the aging duration is not strictly calculated in reverse.

[0032] Based on the aging temperature and duration obtained from the above steps, the microstructure of the alloy blades or disks is determined using the metallographic spectrum and phase diagram of the GH4169 alloy. This allows for the prediction of the macroscopic mechanical properties of the alloy blades or disks, and the targeted optimization of their heat treatment process parameters. Specifically, alloy phase diagrams can be obtained from public databases, metallographic spectra can be obtained by consulting alloy handbooks, or they can be established using microstructure characterization of standard samples.

[0033] In other embodiments, for example, other grades of nickel-based superalloys whose microstructure is more sensitive to aging time, the aging time can be accurately determined by nondestructive testing using the above method.

[0034] In a preferred embodiment, when characterizing the performance parameters of a standard sample or a nickel-based superalloy sample to be characterized, measurements are taken at at least 10 different detection points, and the average value of the results is taken. Meanwhile, to avoid interference from edge regions with eddy currents or ultrasonic waves, the preferred measurement location is at least 3 mm away from the edge of the standard sample or the nickel-based superalloy sample to be characterized.

[0035] In other embodiments, electrical conductivity can be replaced by the Hall coefficient, or hardness, electrical conductivity and Hall coefficient can be used simultaneously to establish a correspondence with heat treatment parameters.

[0036] The purpose of the above embodiments is to provide a further detailed description of the present invention in conjunction with the accompanying drawings, so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present invention, optimization or equivalent substitution of the method steps involved, as well as combination of implementation methods in different embodiments without causing structural and principle conflicts, all fall within the protection scope of the present invention.

Claims

1. A rapid, non-destructive characterization method for nickel-based superalloys, characterized in that, Includes the following steps: Multiple standard samples of nickel-based superalloys, specifically GH4169 alloy, are provided. These standard samples undergo heat treatment under multiple calibration parameters, including heat treatment temperature and heat treatment duration. The heat treatment temperatures used for the standard samples include under-aging temperature, peak aging temperature, and over-aging temperature. Multiple intermediate test temperatures are also set between the under-aging temperature and the peak aging temperature, and between the peak aging temperature and the over-aging temperature. The heat treatment temperatures of these calibration parameters form an arithmetic sequence with a common deviation of 30℃-50℃. The heat treatment durations of these calibration parameters range from 1 hour to 100 hours and form a geometric sequence with a common ratio of 1.5-2.

5. The performance parameters of the standard sample are characterized by non-destructive testing, including at least one of electrical conductivity, Hall coefficient, and hardness. Establish the correspondence between the calibration parameters and the performance parameters; A nickel-based superalloy sample to be characterized is provided, and the performance parameters of the nickel-based superalloy sample are characterized by non-destructive testing. Based on the correspondence between the calibration parameters and performance parameters, the heat treatment temperature and heat treatment duration corresponding to the nickel-based superalloy sample are determined.

2. The rapid non-destructive characterization method for nickel-based superalloys according to claim 1, characterized in that, It also includes a step of correcting the characterization results based on the structure and surface condition of the nickel-based superalloy sample.

3. The rapid non-destructive characterization method for nickel-based superalloys according to claim 1 or 2, characterized in that, Hardness testing methods include ultrasonic hardness testing or Vickers hardness testing.

4. The rapid non-destructive characterization method for nickel-based superalloys according to claim 1 or 2, characterized in that, Before characterizing the performance parameters of the standard sample, the process also includes a grinding and polishing step.

5. The rapid non-destructive characterization method for nickel-based superalloys according to claim 1 or 2, characterized in that, When characterizing the performance parameters, the measurement position should be at least 3 mm away from the edge of the standard sample or nickel-based superalloy sample.

6. The rapid non-destructive characterization method for nickel-based superalloys according to claim 1 or 2, characterized in that, When characterizing the performance parameters, there shall be no fewer than 10 test points on each standard sample or nickel-based superalloy sample.

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