Method for rapidly evaluating residual life of high-temperature material for active service equipment

Abstract

The invention provides a method for rapidly evaluating the residual life of a high-temperature material for active service equipment, and belongs to the field of life evaluation in the field of materials. The method comprises the following steps: firstly, obtaining high-temperature creep relaxation rates and high-temperature creep endurance life information of two or more samples at different temperatures, and determining main curve equations and corresponding parameters ZSRT of different time sequence tissue states; thirdly, main curve equations of different time sequence organization states and corresponding parameters Zc are obtained, and the incidence relation between the ZSRT and the Zc is established; 5, for the to-be-evaluated alloy, obtaining a high-temperature creep relaxation rate main curve equation and a corresponding parameter ZSRT of the to-be-evaluated alloy; and 6, calculating the parameter Zc of the to-be-evaluated alloy by using the incidence relation between the ZSRT and the Zc, and establishing a high-temperature creep endurance life main curve equation through the parameter Zc to realize life evaluation. The method has the advantages of short test time, less material loss, high data utilization rate and the like, and is particularly suitable for evaluating the endurance life caused by the change of the structure state.

Description

Technical Field

[0001] The invention relates to a method for rapidly evaluating the endurance performance of high-temperature materials used in current equipment, and belongs to the field of life evaluation in the field of materials. Background Art

[0002] The endurance life is a key parameter for evaluating the remaining life of high-temperature equipment and an important basis for the practical application of high-temperature materials. Due to the long-term effects of environmental factors such as temperature and stress, high-temperature service components will inevitably experience organizational and performance degradation during service. Therefore, in order to ensure the safety and reliability of the equipment, it is necessary to conduct regular safety inspections and re-evaluate the endurance life of in-service components to determine their reusable service period, i.e., the remaining life.

[0003] At present, the remaining life assessment method mainly relies on the traditional creep endurance test. However, this method is time-consuming and material-intensive, and is not suitable for certain scenarios with tight deadlines or scarce material resources. Therefore, a fast and low-consumption endurance life assessment method is urgently needed to meet the needs of efficient maintenance and remaining life assessment.

[0004] In addition, a large amount of persistent life data is usually accumulated during each maintenance period of the equipment. However, these data often cannot play an effective role in the subsequent maintenance period to provide assistance for the remaining life assessment of the next maintenance period, resulting in a waste of previous data accumulation and test resources. Therefore, how to effectively use the existing data to improve the efficiency and accuracy of the remaining life assessment also attracts relevant engineering practitioners. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention proposes a method for evaluating the endurance life based on high temperature creep relaxation behavior, which is a method for deriving the endurance life by utilizing the sensitivity of high temperature creep relaxation behavior to the material tissue state. By analyzing the creep relaxation behavior and regularity of the material, the method can use the time series data accumulated in the early stage of the component to derive and predict the endurance life of the new state in service. This method not only shortens the test time and reduces material consumption, but also improves the utilization rate of data, providing an efficient and reliable solution for the rapid remaining life assessment of high temperature equipment.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for quickly evaluating the remaining life of high-temperature materials used in current equipment is a life prediction method based on the accumulation of data in a time series. The method first obtains the high-temperature creep relaxation rate and high-temperature creep rupture life information of samples with two or more time series organizational states at different temperatures. Secondly, based on the high-temperature creep relaxation rate data, the master curve equation and corresponding parameter Z of different time series organizational states are determined. SRTThird, for the high temperature creep rupture life data, the master curve equation and corresponding parameter Z of different time sequence microstructure states are obtained. c Fourth, by analyzing the Z under different temporal organization states SRT With Z c , establish the correlation between the two. Fifth, for the alloy to be evaluated, obtain its high temperature creep relaxation rate master curve equation and corresponding parameter Z SRT . Sixth, use the Z established in the early stage SRT With Z c The correlation relationship between the alloy parameters and the parameters Z to be evaluated is calculated. c Finally, the parameter Z of the alloy to be evaluated is used c Establish the main curve equation of high temperature creep rupture life to realize life assessment. It includes the following steps:

[0008] Step 1: Carry out high temperature creep relaxation test and data processing, specifically:

[0009] a: The specimen for high temperature relaxation test is prepared by cutting from a component or sample with a certain organizational state.

[0010] b: Carry out a high temperature creep relaxation test at a specified temperature, the steps are as follows:

[0011] Heat the sample to a specified temperature T SRT Keep the temperature constant, the specified temperature is between 400℃ and 1200℃, and the temperature holding time is between 0.5h and 10h. After the holding time is reached, -6 / s~1.0×10 -2 / s strain rate is steadily loaded to the specified strain, which is within the range of 0.1% to 10.0%. After reaching the specified strain, the specified strain is kept constant for a period of 3h to 200h.

[0012] c: Record the corresponding relationship between stress σ and time t during the first step b.

[0013] d: According to the methods of step b and step c, perform at least one high temperature creep relaxation test at other temperatures, with the temperature range of 400°C to 1200°C, to obtain the stress-time relationship at other specified temperatures.

[0014] e: Based on the relationship between stress σ and time t obtained in step c and step d, the stress change rate is calculated using formula (1)

[0015]

[0016] f: The stress change rate calculated in step e The corresponding stress is used to calculate the high temperature relaxation creep rate at various temperatures and stresses using formula (2): Obtain the corresponding data of temperature-stress-creep relaxation rate, that is, In formula (2), E is the elastic modulus of the material at a specified temperature.

[0017]

[0018] g: For the first step f obtained Using formula Processing to obtain σ~P SRT relationship; among them, P SRT is a parameter variable; C SRT is a constant, and its value is to make different T SRT Down The standard deviation of the data overlap is minimal.

[0019] h: According to the σ~P obtained in the first step g SRT The relationship is fitted using formula (3) to obtain the master curve equation.

[0020] lnσ=a*P SRT 2 +b*P SRT +Z SRT (3)

[0021] In formula (3), lnσ is the natural logarithm of stress σ, and other logarithmic forms can also be used; a is the coefficient of the quadratic term, b is the coefficient of the linear term and Z SRT is a constant term.

[0022] Step 2: Carry out high temperature creep endurance test and data processing, specifically:

[0023] a: Cut and prepare the specimen for creep endurance test from the component or sample. The organizational state of the specimen in this step is the same as that of the specimen in step a.

[0024] b: Implement high temperature creep endurance test: heat the sample to the specified temperature and keep it warm for 0.5h to 10h; after the warming time is reached, apply the specified stress steadily at a stress rate of 5MPa to 20MPa / s; after reaching the specified stress, keep the specified stress unchanged until the sample breaks, and then end the test.

[0025] c: Record the endurance data obtained in the test shown in step 2b.

[0026] d: Refer to step 2b and step 2c and implement other specified temperatures T c Or other high temperature creep endurance tests with specified stress σ to obtain the endurance life t rAmong them, the other specified temperature range is 400°C to 1200°C, the other specified stress range is 10MPa to 1000MPa, and the implemented specified stresses need to be greater than 3.

[0027] e: Through step 2a to step 2d, different temperature-stress-endurance life data are obtained, namely T c -σ-t r .

[0028] f: For T obtained in step e c -σ-t r , using the formula P C =T c (lnt r +C c ) is processed to obtain σ~P C relationship; among them, P C is a parameter variable; C c is a constant, and its value is to make different T c Lower σ-t r The standard deviation of the data overlap is minimal.

[0029] g: According to the σ~P obtained in step f C The relationship is fitted using formula (4).

[0030] lnσ=a ′ *P c 2 +b ′ *P c +Z c (4)

[0031] In formula (4), lnσ is the natural logarithm of stress σ, and other logarithmic forms can also be used; a ′ is the coefficient of the quadratic term, b ′ is the coefficient of the first-order term and Z SRT is a constant term.

[0032] Step 3: Build the model, specifically:

[0033] a: According to the first step, high temperature creep relaxation test is carried out on samples with one or more tissue states changing sequentially and data processing is performed to obtain parameter Z SRT During data processing, parameter C SRT , a and b remain unchanged, parameter Z SRT It varies with the tissue state of the sample.

[0034] b: According to the second step, high temperature creep endurance test is carried out on samples with one or more tissue states changing in time sequence and data processing is performed to obtain parameter Z cThe sample tissue state in this step is the same as the sample tissue state in step 3a. During the data processing, parameter C c 、a ′ and b ′ Keep unchanged, parameter Z c It varies with the tissue state of the sample.

[0035] c: Z of the sample with time-series changes in tissue state obtained from step 3a and step 3b SRT and Z c , which conforms to the relationship shown in formula (5), namely:

[0036] Z SRT =kZ c +c(5)

[0037] In formula (5), k is a coefficient and c is a constant.

[0038] Step 4: Prediction of long-term lifespan, specifically:

[0039] a: For other parts or materials in other organizational states that are to be evaluated for life (referred to as materials to be evaluated), samples are cut to prepare high-temperature creep relaxation test and high-temperature creep endurance test specimens.

[0040] b: According to the first step, the high temperature relaxation test is carried out to obtain the material to be evaluated relation.

[0041] c: Get parameter Z according to step 3 a SRT .

[0042] d: Calculate the Z of the material to be evaluated according to formula (5) in step 3c c .

[0043] e: Substitute the Z obtained in step 4d c Substitute into formula (4) and calculate to obtain σ~P of the material to be evaluated C relationship, achieving lasting life assessment work.

[0044] The beneficial effects of the present invention are:

[0045] (1) Based on the characteristics of high temperature creep relaxation behavior's sensitivity to organizational state, short test time and large amount of data, the present invention analyzes the correlation between the influence of material organizational state differences on its creep relaxation rate and endurance life, and invents a method for predicting endurance life using high temperature creep relaxation behavior. This can alleviate the problem of traditional creep test that it takes a long time to obtain data and consumes a lot of materials.

[0046] (2) The method of the present invention can associate the high-temperature creep relaxation rate of the same material with the endurance life data in different organizational states, thereby realizing the conversion of the short-term high-temperature creep relaxation behavior of the sample to be evaluated into long-term endurance life data. This will reduce the time loss and material loss of the endurance life evaluation based on the traditional high-temperature creep endurance test to a certain extent, and achieve the purpose of rapid evaluation.

[0047] (3) The present invention can use the previous accumulated endurance life data for analysis and modeling, and only needs to supplement the short-time high-temperature creep relaxation test results of the corresponding tissue state samples, which can reduce data redundancy and repetition and improve data utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 The high temperature creep relaxation rate data processing results and master curve of D1 state material;

[0049] Figure 2 It is the high temperature creep rupture life data processing result and main curve of D1 state material;

[0050] Figure 3 The high temperature creep relaxation rate data processing results and master curve of D2 state material;

[0051] Figure 4 It is the high temperature creep rupture life data processing result and main curve of D2 state material;

[0052] Figure 5 Z for D1 and D2 materials SRT and Z c relation;

[0053] Figure 6 The high temperature creep relaxation rate data processing results and master curve of D3 state material;

[0054] Figure 7 Comparison chart of the main curve (dashed line) for predicting the endurance life of D3 material and the experimental data (solid points). DETAILED DESCRIPTION

[0055] The present invention is further described below in conjunction with specific implementation cases.

[0056] The following is a detailed description of the high temperature creep relaxation behavior and endurance life results of Cr25Ni35Nb heat-resistant steel for petrochemical boiler tubes, which specifically includes the following steps:

[0057] Step 1: Carry out high temperature creep relaxation test and data processing, specifically:

[0058] a: A specimen for high temperature relaxation test is prepared by cutting from a sample of the first organizational state (the organizational state is marked as D1) of the high temperature resistant metal material.

[0059] b: Carry out the high temperature creep relaxation test at the specified temperature, the steps are as follows: heat the D1 sample to 900℃ and keep the temperature constant for 0.5h; after the holding time is reached, -5 / s strain rate is steadily loaded to a strain of 1.0% and then the constant strain amount remains unchanged for 12h;

[0060] c: record the corresponding relationship between stress σ and time t during the first step b;

[0061] d: According to the methods of step b and step c, high temperature creep relaxation tests at other temperatures of 930 and 950°C were performed to obtain the relationship between stress and time at 930 and 950°C;

[0062] e: Based on the stress-time relationship obtained in step c and step d, use the formula (Formula (1)) to obtain the stress change rate Relationship with stress;

[0063] f: The stress change rate obtained in step e The relationship between stress σ is as follows: (Formula (2)) Calculate the high temperature relaxation creep rate get relation;

[0064] g: For the first step f obtained use Perform data processing to obtain stress σ and parameter variable P SRT Relationship, the result is Figure 1 As shown. Figure 1 The high temperature creep relaxation rates of D1 materials at different temperatures are basically normalized to the same data band. The value of 1000 is a multiple and is only used for The factor by which the calculated value is reduced in order to facilitate subsequent calculations. It has no actual physical meaning and can be redefined according to specific circumstances during data processing.

[0065] h: Based on the stress σ and parameter variable P obtained in the first step g SRT Relationship (such as Figure 1 A curve is used to represent the normalized data band, which is usually called the main curve, such as Figure 1 Shown by the dashed line. Figure 1 The dashed line in the middle is the formula lnσ=-0.01*P SRT2 -0.28*P SRT +Z SRT (Formula (3)) fitting, where Z SRT =3.38033, this fitting equation is also called the master curve equation.

[0066] Step 2: Carry out high temperature creep endurance test and data processing, specifically:

[0067] a: The specimen for creep endurance test is cut from the D1 specimen;

[0068] b: Implement high temperature creep endurance test: heat the sample to 900℃ and keep it at this temperature for 0.5h; after the holding time, apply 60MPa steadily at a stress rate of 10MPa / s and keep it constant until the sample breaks, and then end the test;

[0069] c: Record the endurance data obtained in the test shown in step 2b;

[0070] d: Referring to step b to step c, perform high temperature creep endurance tests at other specified temperatures or other specified stresses. In this embodiment, 900°C / 50MPa, 950°C / 60MPa, 800°C / 60MPa, etc. are selected to obtain the endurance life t under different temperature or stress conditions. r ;

[0071] e: Through step 2a to step 2d, different temperature-stress-endurance life data are obtained;

[0072] f: For different temperature-stress-endurance life data obtained in the second step, use P C =T c (lgt r +23) / 1000 to process the data and obtain σ~P C Relationship, the result is Figure 2 The value 1000 is a multiple and is only used for The ratio by which the calculated value is reduced to facilitate subsequent calculations. It has no actual physical meaning. The value can be redefined according to specific circumstances during data processing.

[0073] g: According to the σ~P obtained in step f C The relationship is also represented by a master curve, and the master curve equation is lnσ=-0.002*P c 2 +0.08*P c +Z c (Formula (4)), where Z c =8.30335, such as Figure 2 Shown by the solid line.

[0074] Step 3: Build the model, as follows:

[0075] a: According to the first step, a high temperature creep relaxation test is carried out on a sample of the same material as D1 but with a longer service time (marked as D2) and data processing is performed. Set C SRT =-15 and Figure 1 Keeping the same as shown, we get Figure 3 The data band shown. The data band is fitted using formula (3) to obtain the parameter Z of the D2 sample. SRT =3.06737. At this point, the main curve equation of the high temperature creep relaxation rate data band of the D2 state material is lnσ=-0.01*P SRT 2 -0.28*P SRT +3.06737;

[0076] b: According to the second step, the D2 material is subjected to a high temperature creep endurance test and data processing is performed (wherein the parameter C c =23, a ′ = -0.002 and b ′ =-0.08, and Figure 2 Keep consistent), get parameter Z SRT =8.01748. The data band and main curve of D2 material are as follows Figure 4 The main curve equation of the data band for the high temperature creep rupture life of D2 material is lnσ=-0.002*P c 2 +0.08*P c +8.01748;

[0077] c: Based on Z of D1 material and D2 material SRT and Z c , draw as Figure 5 Parameter Z SRT and Z c It presents a linear relationship, using the formula Z SRT =kZ c +c for fitting analysis. Where k = 1, c = -4.93932, that is, Z SRT =Z c -4.93932 (formula (5)).

[0078] Step 4: Prediction of longevity, as follows:

[0079] a: For parts or materials with other organizational states (the organizational state is marked as D3) to be evaluated for life, samples are cut to prepare high temperature creep relaxation test and high temperature creep rupture test;

[0080] b: According to the first step, high temperature relaxation test was carried out to obtain D3 material relation;

[0081] c: According to step 3a, parameter C SRT = -15, a = -0.01 and b = -0.28 (with Figure 1 Keep it consistent) Substitute into formula (3) Figure 6 The data band shown is fitted to obtain the parameter Z of D3 material SRT =2.95862, the result is Figure 6 So far, the main curve equation of the high temperature creep relaxation rate data band of the D3 state material is lnσ=-0.01*P SRT 2 -0.28*P SRT +2.95862;

[0082] d: Z of D3 material SRT =2.95862Substitute into formula (5) and get Z of D3 material c =7.89794, that is, Figure 5 The position indicated by the intersection of the middle dotted line;

[0083] e: Change the Z of D3 material in step 4d to c =7.89794 is substituted into formula (4), and the main curve equation of the predicted endurance life data band is obtained as lnσ=-0.002*P c 2 +0.08*P c +7.89794, the main curve calculated according to this equation is as follows Figure 7 In order to further improve the credibility of the prediction results, a small number of creep endurance tests were carried out for verification. The results are shown in Figure 7 It can be seen that the test data is very close to the inferred curve, and the prediction accuracy meets the conventional needs.

[0084] The above-described embodiments merely express the implementation methods of the present invention, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for rapidly evaluating the remaining life of high temperature materials used in current equipment, characterized in that: The method first obtains the high temperature creep relaxation rate and high temperature creep rupture life information of samples of two or more sequential organizational states at different temperatures; secondly, the master curve equation and corresponding parameter Z of different sequential organizational states are determined based on the high temperature creep relaxation rate data. SRT ; Third, for the high temperature creep endurance life data, the master curve equation and corresponding parameter Z of different time sequence organizational states are obtained. c ; Fourth, by analyzing Z under different temporal organization states SRT With Z c , establish the correlation between the two; Fifth, for the alloy to be evaluated, obtain its high temperature creep relaxation rate master curve equation and corresponding parameter Z SRT ; Sixth, using the Z established in the early stage SRT With Z c The correlation relationship between the alloy parameters and the parameters Z to be evaluated is calculated. c ; Finally, the parameter Z of the alloy to be evaluated is used c The master curve equation of high temperature creep rupture life is established to realize life assessment.

2. A method for rapidly evaluating the remaining life of high temperature materials for in-service equipment according to claim 1, characterized in that: The following steps are involved: Step 1: Carry out high temperature creep relaxation test and data processing, specifically: a: The specimen for high temperature relaxation test is cut from a component or sample with a certain organizational state; b: Carry out a high temperature creep relaxation test at a specified temperature, the steps are as follows: Heat the sample to a specified temperature T SRT Keep the temperature constant, the specified temperature is between 400℃ and 1200℃, and the temperature holding time is between 0.5h and 10h. After the holding time is reached, -6 / s~1.0×10 -2 / s strain rate is steadily loaded to the specified strain, which is within the range of 0.1% to 10.0%; after reaching the specified strain, the specified strain is kept constant for a period of 3h to 200h; c: record the corresponding relationship between stress σ and time t during the first step b; d: According to the methods of step b and step c, carry out at least one high temperature creep relaxation test at other temperatures, the temperature range is 400℃~1200℃, and obtain the stress and time relationship at other specified temperatures; e: Based on the relationship between stress σ and time t obtained in step c and step d, the stress change rate is calculated using formula (1) f: The stress change rate calculated in step e The corresponding stress is used to calculate the high temperature relaxation creep rate at various temperatures and stresses using formula (2): Obtain the corresponding data of temperature-stress-creep relaxation rate, that is, In formula (2), E is the elastic modulus of the material at a specified temperature; g: For the first step f obtained Using formula Processing to obtain σ~P SRT relationship; among them, P SRT is a parameter variable; C SRT is a constant; h: According to the σ~P obtained in the first step g SRT Relationship, using formula (3) for fitting processing, to obtain the main curve equation; lnσ=a*P SRT 2 +b*P SRT +Z SRT (3) Among them, la is the coefficient of the quadratic term, b is the coefficient of the linear term and Z SRT is a constant term; Step 2: Carry out high temperature creep endurance test and data processing, specifically: a: Cut and prepare the specimen for creep endurance test from the component or sample. The tissue state of the specimen in this step is the same as that of the specimen in step a; b: Implement high temperature creep endurance test: heat the sample to the specified temperature and keep it warm for 0.5h to 10h; after the warming time is reached, apply the specified stress steadily at a stress rate of 5MPa to 20MPa / s; after reaching the specified stress, keep the specified stress unchanged until the sample breaks, and then end the test; c: Record the endurance data obtained in the test shown in step 2b; d: Refer to step 2b and step 2c and implement other specified temperatures T c Or other high temperature creep endurance tests with specified stress σ to obtain the endurance life t r ; Among them, the other specified temperature range is 400℃~1200℃, the other specified stress range is 10MPa~1000MPa, and the specified stress implemented needs to be greater than 3; e: Through step 2a to step 2d, different temperature-stress-endurance life data are obtained, namely T c -σ-t r ; f: For T obtained in step e c -σ-t r , using the formula P C =T c (lnt r +C c ) is processed to obtain σ~P C relationship; among them, P C is a parameter variable; C c is a constant, and its value is to make different T c Lower σ-t r The standard deviation of the data overlap is minimal; g: According to the σ~P obtained in step f C Relationship, using formula (4) for fitting analysis; lnσ=a ′ *P c 2 +b ′ *P c +Z c (4) Among them, a ′ is the coefficient of the quadratic term, b ′ is the coefficient of the first-order term and Z SRT is a constant term; Step 3: Build the model, specifically: a: According to the first step, high temperature creep relaxation test is carried out on samples with one or more tissue states changing sequentially and data processing is performed to obtain parameter Z SRT ; During data processing, parameter C SRT , a and b remain unchanged, and the parameter Z SRT It varies with the tissue state of the specimen; b: According to the second step, high temperature creep endurance test is carried out on samples with one or more tissue states changing in time sequence and data processing is performed to obtain parameter Z c ; The sample tissue state in this step is the same as the sample tissue state in step a; during data processing, parameter C c 、a ′ and b ′ Keep unchanged, parameter Z c It varies with the tissue state of the specimen; c: Z of the sample with time-series changes in tissue state obtained from step 3a and step 3b SRT and Z c , which conforms to the relationship shown in formula (5), namely: Z SRT =kZ c +c(5) In formula (5), k is a coefficient and c is a constant; Step 4: Prediction of long-term lifespan, specifically: a: Components or materials in other organizational states to be evaluated for life are called materials to be evaluated, and are cut to prepare high-temperature creep relaxation test and high-temperature creep rupture test specimens; b: According to the first step, the high temperature relaxation test is carried out to obtain the material to be evaluated relation; c: Get parameter Z according to step 3 a SRT ; d: Calculate the Z of the material to be evaluated according to formula (5) in step 3c c ; e: Substitute the Z obtained in step 4d c Substitute into formula (4) and calculate to obtain σ~P of the material to be evaluated C relationship, achieving lasting life assessment work.

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