A method for quantitatively characterizing the microstructure aging of high-temperature materials

Abstract

This invention provides a method for quantitatively characterizing the aging behavior of high-temperature materials, belonging to the field of new materials technology. Based on the correspondence between tissue state and relaxation creep behavior, this invention extracts and establishes a quantitative relationship between characteristic parameters and tissue aging time to obtain the tissue aging behavior. Through this tissue aging behavior, it is possible to deduce the aging behavior over different aging times (t). a The parameter D is used to further derive the relaxation creep rate for this aging time; on the other hand, the tissue aging parameter D can be obtained for unknown samples to derive the equivalent temperature / time. This invention is simple and will help people break through the existing subjective qualitative understanding of tissue aging laws, thereby objectively and quantitatively evaluating the tissue aging laws of newly developed materials. This invention is quick to apply, allowing for rapid quantitative characterization of the tissue aging state and performance evaluation of materials, thus shortening the time required by traditional evaluation methods and accelerating the development cycle of new materials.

Description

Technical Field

[0001] This invention relates to a method for quantitatively characterizing the aging behavior of high-temperature materials, belonging to the testing-related activities carried out in the field of new materials for the development of new materials. It is a method that uses short-time constant strain relaxation creep behavior to quantitatively reflect the current microstructure characteristics of materials. Background Technology

[0002] High-temperature materials inevitably undergo microstructural aging during service due to environmental factors such as temperature and pressure, leading to performance degradation and potentially impacting equipment safety. Quantitatively evaluating the microstructural aging process is crucial for objectively understanding the aging and performance degradation patterns of high-temperature materials. However, traditional microstructural evaluation methods are mostly qualitative, lacking objective quantitative assessment capabilities. This hinders efficient understanding of the serviceability of new materials and impacts their research, development, and feasibility verification.

[0003] Based on this, the present invention proposes a method for quantitatively characterizing the aging law of high-temperature materials. By utilizing the constant strain relaxation creep behavior, which mainly reflects the current microstructure, the present invention quantitatively characterizes the current microstructure of high-temperature materials, thereby quantitatively evaluating the microstructure aging law of high-temperature materials. Summary of the Invention

[0004] To address the qualitative limitations of existing methods for evaluating tissue aging and the need for quantitative characterization of tissue aging, this invention proposes a method for quantitatively characterizing the aging behavior of high-temperature materials. By utilizing the constant strain relaxation creep behavior, which primarily reflects the current tissue state, this method quantitatively characterizes the current tissue state of high-temperature materials, thereby quantitatively evaluating their aging behavior.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for quantitatively characterizing the aging behavior of high-temperature materials, based on the correspondence between tissue state and relaxation creep behavior, extracts and establishes a quantitative relationship between characteristic parameters and tissue aging time, including the following steps:

[0007] The first step is to conduct a high-temperature relaxation test on the initial sample to obtain the normalized master curve equation of the initial sample.

[0008] Step a: Cut and prepare initial samples from the sample for aging treatment and high-temperature relaxation tests;

[0009] Step b involves subjecting the initial sample obtained in step a to a high-temperature relaxation test: holding the sample at a test temperature of 400℃ to 1200℃ for 0.5h to 10h, followed by a relaxation at 1.0×10⁻⁶. -6 / s~1.0×10 -2A constant strain rate of 0.1% to 5.0% strain is applied, and then the current strain is kept constant to obtain the relationship between stress σ and time t.

[0010] Step c: Based on the relationship between stress σ and time t in step b, the relaxation creep rate of the initial sample is calculated using formula (1).

[0011]

[0012] in, Let E be the rate of stress change, and E be the elastic modulus at the test temperature.

[0013] Step d, for the relaxation creep rate of the initial sample obtained in step c. Normalization calculations were performed using the Larson-Miller parametric equations shown in formula (2).

[0014]

[0015] Among them, P SRT Here are the Larson-Miller parameters, where T is the absolute temperature of the experiment and C is a constant;

[0016] P of the initial sample in steps e and d SRT The stress σ conforms to the relationship shown in formula (3), and the normalized master curve equation is obtained by fitting.

[0017] lnσ=f(P SRT )=a+b*P SRT +c*P SRT 2 (3)

[0018] Where a, b, and c are all constants;

[0019] The second step involves conducting a high-temperature relaxation test on the aged samples to obtain the normalized master curve equation and quantitative aging structure of the aged samples.

[0020] Step f: The initial sample obtained in step a for aging treatment is subjected to aging at 400℃ to 1200℃ for a time t. a For aging treatment tests ranging from 5 hours to 10,000 hours, aging samples were prepared.

[0021] Step g: Perform a high-temperature relaxation test on the aged specimens obtained in step f: hold at a test temperature of 400℃~1200℃ for 0.5h~10h, then apply a 1.0×10⁻⁶ ppm pressure. -6 / s~1.0×10 -2A constant strain rate of 0.1% to 5.0% strain is applied, and then the current strain is kept constant to obtain the relationship between stress σ and time t.

[0022] In step h, based on the relationship between stress σ and time t obtained in step g, the relaxation creep rate of the aged specimen is calculated using formula (1).

[0023] Step i, use formula (2) to determine the relaxation creep rate of the aged sample. Calculations were performed to obtain the stress and P of the aged specimen. SRT relation;

[0024] In step j and step i, the P of the aged sample SRT The stress σ conforms to the relationship shown by the normalized principal curve equation of formula (4).

[0025] lnσ=f(P SRT )+D (4)

[0026] Where D is a constant, defined as a tissue aging parameter, with the initial sample having D = 0. The third step is to obtain the tissue aging pattern.

[0027] Step k, in formula (4), parameter D and the effective time t a The relationship shown in Formula (5) is obtained by fitting the tissue aging parameters and the aging time or aging period shown in Formula (5), which is the tissue aging law (through this law, the performance of longer aging periods can be further predicted).

[0028]

[0029] In formula (5), d, e, and f are all constants.

[0030] In addition to obtaining different tissue aging samples by controlling the isothermal aging time in the second step of this invention, other aging methods (such as service aging, damage, etc.) can also be used to obtain different aged tissues, thereby quantitatively characterizing the aged tissues and obtaining the tissue aging patterns.

[0031] The tissue aging law shown in formula (5) is finally obtained through this invention. Applying this invention: on the one hand, it can derive different aging times t. a The parameter D (representing different aged tissues) can be combined with formula (4) to further derive the relaxation creep rate of the aging time; on the other hand, the tissue aging parameter D can be obtained for unknown samples, and the equivalent temperature / time can be derived by combining formula (5).

[0032] The innovativeness of this invention is analyzed as follows:

[0033] (1) Based on the lack of quantitative characterization methods for aging tissues and the need for such methods, and combined with relaxation creep behavior and its regularity, a parameter D that can quantitatively characterize tissue aging is proposed.

[0034] (2) Based on the correlation between the alloy microstructure aging parameter D and the aging time, a formula that can reflect the microstructure aging law was established.

[0035] The beneficial effects of this invention are as follows:

[0036] (1) The method of the present invention is simple and will help people break through the existing subjective qualitative understanding of the aging law of tissues, thereby objectively and quantitatively evaluating the aging law of newly developed materials.

[0037] (2) The present invention is quick to apply, and people can quickly and quantitatively characterize the aging state of materials and evaluate their performance, thereby shortening the time of traditional evaluation methods and helping to accelerate the development cycle of new materials. Attached Figure Description

[0038] Figure 1 The creep relaxation stress-time relationship of the initial sample;

[0039] Figure 2 The creep relaxation rate of the initial sample;

[0040] Figure 3 The result is the normalized creep relaxation rate of the initial sample.

[0041] Figure 4 The creep relaxation stress-time relationship of the aged specimen; Figure 4 (a) is a graph showing the creep relaxation stress-time relationship of the specimen aged at 900℃ / 20h; Figure 4 (b) is a graph showing the creep relaxation stress-time relationship of the specimen aged at 900℃ / 500h; Figure 4 (c) is the creep relaxation stress-time relationship diagram of the specimen aged at 900℃ / 2000h; Figure 4 (d) is the creep relaxation stress-time relationship diagram of the specimen aged at 900℃ / 5000h;

[0042] Figure 5 The creep relaxation rate of the aged sample; Figure 5 (a) is the creep relaxation rate-stress relationship diagram of the specimen aged at 900℃ / 20h; Figure 5 (b) Creep relaxation rate-stress diagram of the specimen aged at 900℃ / 500h; Figure 5 (c) Creep relaxation rate-stress diagram of the specimen aged at 900℃ / 2000h; Figure 5 (d) is the creep relaxation rate-stress diagram of the specimen aged at 900℃ / 5000h;

[0043] Figure 6 This represents the normalized result of creep relaxation for aged samples. Figure 6 (a) is a normalized graph of creep relaxation rate of the specimen aged at 900℃ / 20h; Figure 6 (b) is a normalized plot of creep relaxation rate of the specimen aged at 900℃ / 500h; Figure 6 (c) is a normalized plot of creep relaxation rate of the specimen aged at 900℃ / 2000h; Figure 6 (d) is a normalized plot of creep relaxation rate of the specimen aged at 900℃ / 5000h;

[0044] Figure 7 The variation law of tissue aging parameter D (900℃). Detailed Implementation

[0045] The present invention will be further described below with reference to specific embodiments.

[0046] This invention is based on the characteristic that the relaxation creep behavior of high-temperature materials mainly reflects the current microstructure. It achieves quantitative characterization of the microstructure aging law of high-temperature materials by establishing a correlation model between relaxation creep behavior and microstructure aging parameters. The specific implementation of this invention is described in detail below with reference to relevant results from a nickel-based superalloy:

[0047] The first step is to conduct a high-temperature relaxation test on the initial sample to obtain the normalized master curve equation of the initial sample.

[0048] Step a: Cut a sample from the sample material and name it the initial sample. Part of the initial sample is used to prepare for the high-temperature relaxation creep test, and part is used for aging treatment;

[0049] Step b involves subjecting the initial sample obtained in step a to a high-temperature relaxation creep test: after holding at test temperatures of 750, 850, and 950°C for 2 hours, a creep retardation test is performed at 8.0 × 10⁻⁶ ppm. -5 A strain rate of / s was applied to a strain of 2.0%, and then the current strain was kept constant for approximately 24 hours. The relationship between stress σ and time t was obtained, and the results are as follows: Figure 1 As shown; in step c, based on the relationship between stress σ and time t in step b, the relaxation creep rate is calculated using formula (1). The results are as follows Figure 2 As shown. In formula (1), Let E be the rate of stress change, and E be the elastic modulus at the test temperature.

[0050]

[0051] Step d, for the relaxation creep rate of the initial sample obtained in step c. The calculation was performed using the Larson-Miller parametric equation shown in formula (2), and the results are as follows: Figure 3 As shown. In formula (2), P SRT Here are the Larson-Miller parameters, and T is the absolute temperature of the experiment;

[0052]

[0053] P of the initial sample in steps e and d SRT The stress σ conforms to the relationship shown in formula (3). In formula (3), a, b, and c are all constants. Figure 3 The results shown and formula (3) yield the equation shown in formula (4);

[0054] lnσ=f(P SRT )=a+b*P SRT +c*P SRT 2 (3)

[0055] lnσ=5.595-1.049×10 -4 P SRT -1.355×10 -9 P SRT 2 (4)

[0056] The second step involves conducting a high-temperature relaxation test on the aged samples to obtain the normalized master curve equation and quantitative aging structure of the aged samples.

[0057] Step f: The initial sample obtained in step a is aged at 900℃ for a time t. a Aging samples were prepared for aging treatment tests of 20, 500, 2000, and 5000 hours.

[0058] Step g: Perform a high-temperature relaxation test on the aged samples obtained in step f: hold at test temperatures of 750, 850, and 950°C for 2 hours, then apply a high-temperature relaxation test at 8.0 × 10⁻⁶. -5 A strain rate of / s was applied to a strain of 2.0%, and then the current strain was kept constant for approximately 24 hours. The relationship between stress σ and time t was obtained, and the results are as follows: Figure 4 As shown;

[0059] Step h, based on step c Figure 4 The stress σ and time t shown are used to calculate the relaxation creep rate using formula (1). The results are as follows Figure 5 As shown;

[0060] Step i, use formula (2) to determine the relaxation creep rate of the aged sample. Calculations were performed to obtain the P of the aged sample. SRT The result is as follows Figure 6 As shown;

[0061] In step j and step i, the P of the aged sample SRT The stress σ conforms to the relationship shown in formula (5), and the fitting result is shown in... Figure 6 In formula (5), D is a constant, defined as a tissue aging parameter;

[0062] lnσ=5.595-1.049×10 -4 P SRT -1.355×10 -9 P SRT 2 +D(5)

[0063] The third step is to obtain the patterns of tissue aging and damage.

[0064] Step k, the parameter D in formula (5) and the effective time t a The relationship between them conforms to the relationship shown in formula (6), and the result is as follows. Figure 7 As shown. The initial sample's D value is 0.

[0065]

[0066] Analysis of the results of this invention: This invention obtained the microstructure aging law of a nickel-based superalloy at 900℃, namely formula (6). Further, the microstructure aging parameter D for other aging times can be calculated. For example, if the aging time is 10000 hours, substituting into formula (6) yields D = -0.2815, which is the quantitative parameter of the microstructure of the alloy after aging treatment at 900℃ for 10000 hours.

[0067] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A method for quantitatively characterizing the aging behavior of high-temperature materials, characterized in that, The method, based on the correspondence between tissue state and relaxation creep behavior, extracts and establishes a quantitative relationship between feature parameters and tissue aging time, including the following steps: The first step is to conduct a high-temperature relaxation test on the initial sample to obtain the normalized master curve equation of the initial sample. Step a: Cut and prepare initial samples from the sample for aging treatment and high-temperature relaxation tests; Step b: Perform a high-temperature relaxation test on the initial sample obtained in step a to obtain the relationship between stress σ and time t; Step c: Based on the relationship between stress σ and time t in step b, the relaxation creep rate of the initial sample is calculated using formula (1). in, Let E be the rate of stress change, and E be the elastic modulus at the test temperature. Step d, for the relaxation creep rate of the initial sample obtained in step c. The Larson-Miller parametric equations shown in formula (2) are used for normalization calculation; Among them, P SRT Here are the Larson-Miller parameters, where T is the absolute temperature of the experiment and C is a constant; P of the initial sample in steps e and d SRT The stress σ conforms to the relationship shown in formula (3), and the normalized master curve equation is obtained by fitting. lnσ=f(P SRT )=a+b*P SRT +c*P SRT 2 (3) Where a, b, and c are all constants; The second step is to conduct a high-temperature relaxation test on the aged samples to obtain the normalized master curve equation and quantitative aging structure of the aged samples. Step f: The initial sample obtained in step a for aging treatment is subjected to aging at 400℃ to 1200℃ for a time t. a For aging treatment tests ranging from 5 hours to 10,000 hours, aging samples were prepared. Step g: Perform a high-temperature relaxation test on the aged specimen obtained in step f to obtain the stress σ. -D The correspondence with time t; Step h, based on the stress lnσ obtained in step g. -D The relaxation creep rate of the aged specimen was calculated using formula (1) based on the relationship with time t. Step i, use formula (2) to determine the relaxation creep rate of the aged sample. Calculations were performed to obtain the stress and P of the aged specimen. SRT-D relation; In step j and step i, the P of the aged sample SRT-D With stress σ -D The relationship is consistent with the normalized principal curve equation shown in formula (4); lnσ -D =f(P SRT )+D (4) Where D is a constant, defined as a tissue aging parameter, and the initial sample D = 0; The third step is to obtain the patterns of tissue aging. The tissue aging pattern shown in formula (5) was obtained by fitting the data. In formula (5), d, e, and f are all constants; Based on the tissue aging pattern shown in formula (5), the aging time t for different aging periods can be derived. a The parameter D, combined with formula (4), can be used to further derive the relaxation creep rate of the aging time.

2. The method for quantitatively characterizing the aging behavior of high-temperature materials according to claim 1, characterized in that, In step b, the high-temperature relaxation test is performed by holding the product at a test temperature of 400℃ to 1200℃ for 0.5h to 10h, followed by applying a 1.0×10⁻⁶ ppm solution. -6 / s~1.0×10 -2 A constant strain rate of 0.1% to 5.0% strain is applied, and then the current strain is kept constant to obtain the relationship between stress σ and time t.

3. The method for quantitatively characterizing the aging behavior of high-temperature materials according to claim 1, characterized in that, In step g, the high-temperature relaxation test is performed by holding the product at a test temperature of 400℃ to 1200℃ for 0.5h to 10h, followed by applying a 1.0×10⁻⁶ ppm solution. -6 / s~1.0×10 -2 A constant strain rate of 0.1% to 5.0% strain is applied, and then the current strain is kept constant to obtain the stress σ. -D The correspondence between time t and time t.

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