Rapid lossless characterization method of nickel-based superalloy

Abstract

A rapid lossless characterization method of nickel-based superalloy comprises the following steps: providing a standard sample, and carrying out heat treatment under calibration parameters; carrying out nondestructive testing on the standard sample to characterize multiple performance parameters of the standard sample, and establishing a corresponding relation between the multiple performance parameters and the calibration parameters; and performing the same nondestructive testing on the nickel-based superalloy sample, performing inversion according to the corresponding relationship between the performance parameters and the calibration parameters, and determining the heat treatment temperature and the heat treatment duration corresponding to the characterization result of the nickel-based superalloy sample. According to the method, the unique corresponding relation between heat treatment parameters and multiple performance parameters is established through the inconsistency of the change trend of different performance parameters of the nickel-based superalloy along with the heat treatment evolution process, and therefore rapid characterization of the nickel-based superalloy structure is achieved.

Description

Technical Field

[0001] The invention belongs to the field of material characterization, and in particular relates to a rapid non-destructive characterization method for a nickel-based high-temperature alloy. Background Art

[0002] Nickel-based superalloys have good high-temperature mechanical properties and are therefore widely used in the manufacture of aero-engine components. Most nickel-based superalloys are heat-treatable alloys and require different heat treatment processes to form strengthening phases such as γ', γ" or δ in their γ matrix to enhance the performance of nickel-based superalloys. Researching and formulating a heat treatment system for nickel-based superalloys to obtain the required microstructure is an important task in the development of nickel-based superalloy manufacturing processes. At present, scanning electron microscopes (SEM) or transmission electron microscopes (TEM) and other equipment are usually used to directly observe the microstructure of nickel-based superalloys treated with different process parameters to determine the effects of different heat treatment processes on the microstructure of nickel-based superalloys. In this process, a destructive sampling method is required to prepare a large number of nickel-based superalloy samples, which has a long cycle, high cost, and a complex characterization process, resulting in a prolonged optimization process for the heat treatment process parameters of nickel-based superalloys, an increase in the process development cost, and an inability to adapt to the increasingly complex and diverse process development needs of aero-engines. Therefore, providing a rapid and non-destructive characterization method for nickel-based superalloys is of high value for optimizing the development cycle and cost of nickel-based superalloy processes. Summary of the invention

[0003] The object of the present invention is to provide a rapid non-destructive characterization method for a nickel-based high-temperature alloy, and to determine the heat treatment parameters experienced by the nickel-based high-temperature alloy through non-destructive testing.

[0004] According to an embodiment of the present invention, a method for rapid non-destructive characterization of a nickel-based high-temperature alloy is provided, the method comprising the following steps: providing a plurality of standard specimens of the nickel-based high-temperature alloy, the standard specimens being heat treated under a plurality of calibration parameters, respectively, the calibration parameters comprising a heat treatment temperature and a heat treatment duration; characterizing performance parameters of the standard specimens by non-destructive testing, the performance parameters comprising at least one of electrical conductivity and Hall coefficient and hardness; establishing a correspondence between the calibration parameters and the performance parameters; providing a nickel-based high-temperature alloy sample to be characterized, and characterizing the performance parameters of the nickel-based high-temperature alloy sample by non-destructive testing; and determining the heat treatment temperature and heat treatment duration corresponding to the nickel-based high-temperature alloy sample according to the correspondence between the calibration parameters and the performance parameters.

[0005] During the heat treatment process of nickel-based superalloys, the change of single performance parameters such as hardness and conductivity with the heat treatment temperature or time is not monotonous. For example, before peak aging, the microstructure hardness of nickel-based superalloys increases with the increase of heat treatment temperature, but after peak aging, the hardness decreases with the increase of temperature. However, the evolution laws of different performance parameters are not the same. By coupling conductivity or Hall coefficient with hardness, a comparison relationship between heat treatment parameters and microstructure performance of nickel-based superalloys can be established. This comparison relationship can be used to determine the heat treatment process experienced by nickel-based superalloys according to performance parameters by inversion, thereby achieving effective characterization of nickel-based superalloys without microstructure analysis.

[0006] Furthermore, in some embodiments, the method further includes the step of correcting the characterization result according to the structure and surface state of the nickel-based high-temperature alloy sample. Nickel-based high-temperature alloy samples such as blades have complex profile structures and different surface states, which may cause errors in the measurement results, and the measurement results need to be corrected to compensate for the errors.

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

[0008] Furthermore, in some embodiments, the heat treatment temperatures of the multiple calibration parameters adopted by the standard sample include: under-aging temperature, peak aging temperature and over-aging temperature, and 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.

[0009] Furthermore, in some embodiments, the heat treatment temperatures of the multiple calibration parameters are in an arithmetic progression with a tolerance of 30°C-50°C.

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

[0011] Furthermore, in some embodiments, the heat treatment times of the multiple calibration parameters form a geometric progression 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 also included.

[0013] Furthermore, in some embodiments, when characterizing the performance parameters, the distance between the measurement position and the edge of the standard sample or the nickel-based high-temperature alloy sample is not less than 3 mm.

[0014] Furthermore, in some embodiments, when characterizing the performance parameters, the number of detection points on each of the standard specimens or nickel-based high-temperature alloy samples is no less than 10. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a hardness-conductivity relationship diagram of a standard sample in an embodiment;

[0016] Figure 2 1 is an isothermal transformation diagram of GH4169 nickel-based high-temperature alloy in one embodiment.

[0017] The purpose of the above drawings is to explain the present invention in detail so that those skilled in the art can understand the technical concept of the present invention, but it is not intended to limit the present invention. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0019] Reference to "embodiment" herein means that a particular feature, structure or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present invention. The phrase appearing in various locations in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive independent or alternative embodiments. It should be understood by those skilled in the art that the embodiments herein may be combined with other embodiments without structural conflicts. In the description herein, "multiple" means at least two.

[0020] Nickel-based superalloys are widely used in key aerospace components. Nickel and chromium are the main elements that improve the corrosion resistance of 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 the hardness during aging. Titanium and aluminum elements form a γ' [Ni3(Ti,Al), cubic structure] precipitate phase, which is less effective than γ^ in promoting alloy hardening. Another orthorhombic δ phase precipitation has no significant effect on mechanical properties, but if there is too much, it will reduce the performance. When treated at 700 to 800 degrees Celsius for a short time (6–8h), γ' and γ” phases are uniformly precipitated in the matrix. If it is kept at around 800-900℃ for a longer time, the δ phase will be seen to precipitate rapidly, usually with nucleation at the grain boundaries. Therefore, the performance of nickel-based high-temperature alloy parts is closely related to their thermal history. Different heat treatment parameters will have a significant impact on the microstructure characteristics of nickel-based high-temperature alloys, and will have a significant impact on the room temperature mechanical properties, high temperature strength, creep resistance, fatigue performance, etc. of nickel-based high-temperature alloys.

[0021] For a given nickel-based high-temperature alloy sample, it is usually necessary to conduct a microstructure analysis to determine the thermal history of the sample. The alloy microstructure characterization requires cutting a specimen from the sample, grinding and polishing, and etching, and characterizing the phase distribution in the alloy sample structure by scanning electron microscopy (SEM) or transmission electron microscopy (TEM). This characterization process itself is destructive to the sample. At the same time, sample preparation and characterization need to be carried out in a specialized laboratory, which is inefficient and costly. This leads to a longer cycle and higher cost for the optimization process of the nickel-based high-temperature alloy heat treatment process, which cannot fully meet the increasingly diverse design requirements of aerospace engine parts.

[0022] In order to solve the above problems, an embodiment of the present invention provides a rapid non-destructive characterization method for nickel-based high-temperature alloys. The method includes the following process:

[0023] Taking GH4169 alloy as the characterization object, 49 groups of standard specimens (S1-S49) of GH4169 alloy were prepared, each group including at least 3 specimens, each standard specimen size was 10mm×20mm×20mm, and the two surfaces of 20mm×20mm were polished for subsequent characterization. The standard specimens on the lock were fully annealed in a vacuum furnace, and then aged in a vacuum environment under different calibration parameters. The calibration parameters include different aging temperatures and aging durations, as shown in Table 1.

[0024]

[0025] Table 1 Standard sample-calibration parameter comparison table

[0026] The setting of calibration parameters follows the following standards: select the peak aging temperature (720℃) of GH4169, a typical under-aging temperature (600℃) and a typical over-aging temperature (840℃), insert two intermediate test temperatures 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 progression with a tolerance of 40℃; in other embodiments, the intermediate test temperatures can be set to more groups, and the tolerance is preferably 30℃-50℃. Combined with Figure 2 The solid-state phase transformation law reflected by the TTT curve (isothermal transformation curve) of the GH4169 alloy shown in the figure selects the typical heat treatment time range (1-100h) of the GH4169 alloy, and sets 7 heat treatment times (including the endpoints 1h and 100h) as calibration times according to a geometric progression, with a common ratio of 2.15; in other embodiments, more calibration temperatures can also be set, and the common ratio of the geometric progression is preferably 1.5-2.5.

[0027] After aging treatment, nondestructive testing was performed on the standard samples to characterize their hardness and conductivity. The results are as follows: Figure 1The corresponding relationship curve of hardness-conductivity and calibration parameters is shown (according to the TTT curve and the measurement results, the aging temperature has a more significant effect on the performance of the GH4169 alloy, while the aging time has a relatively low degree of influence on the alloy performance within a time period of 1h-100h). Specifically, in some embodiments, the hardness detection method can use an ultrasonic hardness tester to perform hardness detection or a microhardness tester to perform Vickers hardness detection.

[0028] The hardness of GH4169 alloy increases with the increase of temperature and aging time before reaching the peak aging stage, and decreases with the increase of temperature and aging time after entering the over-aging stage. The conductivity of GH4169 also increases with the temperature and aging time before a heat treatment peak, and decreases with the increase of temperature and aging time after exceeding the peak. Therefore, the hardness or conductivity alone cannot determine the heat treatment process experienced by GH4169, nor can it predict the microstructure state of the alloy; but the hardness and conductivity of GH4169 do not coincide with the change trend of heat treatment parameters. Therefore, by coupling the hardness value with the conductivity, it is possible to infer a unique heat treatment state, and then determine the microstructure of the material through the phase diagram and metallographic spectrum of the nickel-based alloy, and then predict 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 blade disk, and the hardness and electrical conductivity of the alloy sample are tested using the same characterization method. 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 blisks, Figure 1 The hardness-conductivity and calibration parameter corresponding relationship curve shown are inversely calculated to determine the aging temperature and aging treatment time corresponding to the alloy blade or blade disk.

[0031] like Figure 1 As shown in Figure 1, according to the different aging temperatures in the calibration parameters, the calibration data points are divided into 7 clusters, among which 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 manner. Figure 1 Compare and find the cluster corresponding to the measurement result to determine the aging temperature of the alloy blade or blade disk; when the measurement result falls into cluster 1, cluster 6 or cluster 7, the influence of aging time on the performance parameters is more obvious, and the aging temperature can be determined according to the measurement result. Figure 1 The aging time corresponding to the alloy blade or blade disk is determined according to the distribution of cluster data points in the standard sample. For example, when the measurement result is Figure 1 The position in is close to S1 in cluster 1, so it can be determined that its aging time is about 1h; when the measurement result is Figure 1 The position in cluster 7 is close to S49, so it can be determined that the aging time is about 100h. Since the significance of the aging time in the microstructure evolution of GH4169 alloy is weak, when the measurement results are Figure 1 When the alloy blades or disks fall into clusters 2 to 5, no strict inverse calculation is performed on the aging time of the alloy blades or disks.

[0032] According to the aging temperature and aging time obtained in the above steps, the microstructure of the alloy blade or blade disk is determined through the metallographic spectrum and phase diagram of the GH4169 alloy, and then the macroscopic mechanical properties of the alloy blade or blade disk are predicted, and the heat treatment process parameters are optimized in a targeted manner. Specifically, the alloy phase diagram can be queried through a public database, the metallographic spectrum can be obtained by consulting an alloy manual, or it can be established by using a standard sample for microstructure characterization.

[0033] In other embodiments, for example, other grades of nickel-based high-temperature alloys whose alloy microstructures are more sensitive to aging duration, their aging durations can be accurately determined through non-destructive testing using the above method.

[0034] In a preferred embodiment, when the performance parameters of the standard sample or the nickel-based high-temperature alloy sample to be characterized are characterized, the measurement is performed at least at 10 different detection points, and the detection results are averaged. At the same time, in order to avoid the edge area from interfering with the eddy current or ultrasonic wave, the preferred measurement position is not less than 3 mm from the edge of the standard sample or the nickel-based high-temperature alloy sample to be characterized.

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

[0036] The purpose of the above embodiments is to further explain the present invention in detail 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, the optimization or equivalent replacement of the method steps involved, and the combination of the implementation methods in different embodiments without conflict of structure and principle, all fall within the protection scope of the present invention.

Claims

1. A rapid non-destructive characterization method for nickel-based high-temperature alloys, characterized in that: The following steps are involved: Providing a plurality of standard samples of nickel-based high-temperature alloys, wherein the standard samples are heat treated under a plurality of calibration parameters, wherein the calibration parameters include a heat treatment temperature and a heat treatment time; Characterizing the performance parameters of the standard sample by nondestructive testing, wherein the performance parameters include at least one of conductivity and Hall coefficient and hardness; Establishing a corresponding relationship between the calibration parameters and the performance parameters; Providing a nickel-based high-temperature alloy sample to be characterized, and characterizing the performance parameters of the nickel-based high-temperature alloy sample by non-destructive testing; According to the corresponding relationship between the calibration parameters and the performance parameters, the heat treatment temperature and heat treatment time corresponding to the nickel-based high-temperature alloy sample are determined.

2. The rapid non-destructive characterization method of nickel-based high-temperature alloy according to claim 1, characterized in that: The method also includes the step of correcting the characterization result according to the structure and surface state of the nickel-based high-temperature alloy sample.

3. The rapid non-destructive characterization method of nickel-based high-temperature alloy 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 of nickel-based high-temperature alloy according to claim 1 or 2, characterized in that: The heat treatment temperatures of the multiple calibration parameters used by the standard sample include: under-aging temperature, peak aging temperature and over-aging temperature, and 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.

5. The rapid non-destructive characterization method of nickel-based high-temperature alloy according to claim 4, characterized in that: The heat treatment temperatures of the multiple calibration parameters form an arithmetic progression with a tolerance of 30°C-50°C.

6. The rapid non-destructive characterization method of nickel-based high-temperature alloy according to claim 1 or 2, characterized in that: The heat treatment time of the multiple calibration parameters is 1h-100h.

7. The rapid non-destructive characterization method of nickel-based high-temperature alloy according to claim 6, characterized in that: The heat treatment times of the multiple calibration parameters form a geometric progression, and the common ratio is 1.5-2.

5.

8. The rapid non-destructive characterization method of nickel-based high-temperature alloy according to claim 1 or 2, characterized in that: Before characterizing the performance parameters of the standard sample, the method further includes a step of grinding and polishing the standard sample.

9. The rapid non-destructive characterization method of nickel-based high-temperature alloy according to claim 1 or 2, characterized in that: When characterizing the performance parameters, the distance between the measuring position and the edge of the standard sample or the nickel-based high-temperature alloy sample is not less than 3 mm.

10. The rapid non-destructive characterization method of nickel-based high-temperature alloy according to claim 1 or 2, characterized in that: When characterizing the performance parameters, there are no less than 10 detection points on each of the standard specimens or nickel-based high-temperature alloy samples.

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