Nickel-based alloy ultra-high cycle fatigue life prediction method, correction method and device

Abstract

This invention discloses a method and correction method for ultra-high-cycle fatigue life prediction of nickel-based alloys, as well as a device for this method. This method obtains the nickel-based alloy's compressive strength through tensile testing and the crack source size through a certain number of ultrasonic vibration fatigue acceleration tests. Based on the theory of fatigue dislocation cumulative damage, this method incorporates material performance parameters and microscopic dimensions to establish an ultra-high-cycle fatigue life prediction formula and correction method based on the nickel-based alloy's mechanical performance parameters and crack source size. This method offers the advantages of simplicity, speed, and accuracy, enabling effective prediction of the ultra-high-cycle fatigue life of high-temperature nickel-based alloys.

Description

Technical Field

[0001] The present invention belongs to the field of high-temperature nickel-based alloys, and in particular relates to a nickel-based alloy ultra-high cycle fatigue life prediction method, a correction method and a device thereof. Background Art

[0002] High temperature nickel-based alloys are widely used in industry due to their excellent mechanical properties, corrosion resistance and creep fatigue resistance over a wide range of typical temperatures. This type of alloy is often used in critical components such as heavy gas turbines and aircraft engine blades. Under such conditions, the material is often subjected to extremely high frequency vibration cyclic loads with a service life of more than 10 7 Cycles, also known as ultra-high cycle fatigue. The prediction of ultra-high cycle fatigue life of high-temperature nickel-based alloys is the basis for the reliable service of structural components in the aerospace and energy fields.

[0003] Research results show that cracks in nickel-based alloys often initiate on the specimen surface during high- and ultra-high-cycle cycles. The crack initiation mechanism and influencing factors for these alloys, such as surface twin boundary cracking models and the influence of surface defects, have become a hot topic in the fatigue field in recent years. Existing ultra-high-cycle fatigue life prediction research has mostly focused on high-strength steels and titanium alloys, where crack initiation tends to shift inward. While some models related to crack initiation depth are applicable, such as the Z parameter model proposed by East China University of Science and Technology (Acta. Mater, 157 (2018): 259-275), some defect models related to crack initiation depth are no longer applicable to nickel-based alloys with surface cracking.

[0004] In addition, the ultra-high cycle fatigue life prediction of nickel-based alloys, especially the prediction models that require easy access to key parameters and are suitable for rapid use in the industry, are still insufficient. For example, the damage accumulation life prediction model proposed by Tsinghua University for 718 nickel-based alloy (Sci. China. Phys. Mech, 56 (2013): 617-623) has good prediction results, but the formula is relatively complex and is not suitable for quick and easy use in the industry.

[0005] At present, the current models and methods cannot guarantee the rapid and accurate prediction of the ultra-high cycle fatigue life of nickel-based alloys in the industry: there are few studies on ultra-high cycle fatigue life prediction models for nickel-based alloys, and there are problems such as some models are not applicable or the parameters and usage processes are complicated. In addition, material performance parameters and key parameters of crack sources are not considered, resulting in poor prediction results and reduced accuracy; secondly, traditional fatigue testing methods are time-consuming and are not suitable for the needs of rapid industrial production and testing. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for predicting ultra-high cycle fatigue life of nickel-based alloys, a correction method and a device thereof.

[0007] The present invention provides the following technical solutions:

[0008] A method for predicting the ultra-high cycle life of a nickel-based alloy comprises the following steps:

[0009] S01: Perform a room temperature tensile test on the nickel-based alloy, draw the tensile curve of the nickel-based alloy, and calculate the elastic modulus E of the room temperature material and the shear modulus G of the material based on the tensile curve;

[0010] S02: Perform hardness test on nickel-based alloy to obtain the material Vickers hardness HV;

[0011] S03: Perform ultrasonic vibration fatigue tests on nickel-based alloys at room temperature with a stress ratio of -1. Take scanning electron microscope (SEM) images of the nickel-based alloy fracture surface, measure the equivalent radius a0 of the crack source of the nickel-based alloy, and calculate the stress intensity threshold value ΔK. th ;

[0012] S04: Substitute the relevant parameters into the ultra-high cycle fatigue life prediction formula of nickel-based alloy to obtain the ultra-high cycle fatigue life N of nickel-based alloy. i .

[0013] Preferably, the stress intensity threshold value ΔK th The calculation method is:

[0014]

[0015] Where HV is the Vickers hardness of the material, area is the crack source area, area=πa0 2 , a0 is the equivalent radius of the crack source.

[0016] Preferably, the fatigue life N i The calculation method is:

[0017]

[0018] Among them, W s is the fracture energy, G is the shear modulus, Δσ is the fatigue stress amplitude, Δσ w is the fatigue limit and β is the life correction factor.

[0019] Preferably, the S03 further includes obtaining ultrasonic vibration fatigue test results, drawing a stress fatigue (SN) curve, and trying to obtain material parameters A and B to obtain a nickel-based alloy life correction factor β, where the calculation formula of the parameter β is:

[0020]

[0021] Where A and B are material parameters, which are tentatively obtained based on the results of ultrasonic vibration fatigue tests; Δσ is the fatigue stress amplitude; and a0 is the equivalent radius of the crack source.

[0022] Preferably, the S03 further includes substituting relevant parameters into the calculation formula (d) to obtain the fracture energy W of the nickel-based alloy. s .

[0023]

[0024] Preferably, the fatigue limit Δσ of the nickel-based alloy w The calculation formula is:

[0025]

[0026] α=0.226+HV×10 -4 (f)

[0027] Among them, C=1.43~1.56.

[0028] Preferably, the calculation formula of the shear modulus G of the material is:

[0029] G=E / 2(1+v) (g)

[0030] Where v is the Poisson's ratio of the nickel-based alloy.

[0031] A method for correcting ultra-high cycle fatigue life prediction of a nickel-based alloy, wherein the steps of ultra-high cycle life prediction of a nickel-based alloy include:

[0032] S01: Perform a room temperature tensile test on the nickel-based alloy, draw the tensile curve of the nickel-based alloy, and calculate the elastic modulus E of the room temperature material and the shear modulus G of the material based on the tensile curve;

[0033] S02: Perform hardness test on nickel-based alloy to obtain the material Vickers hardness HV;

[0034] S03: Perform ultrasonic vibration fatigue tests on nickel-based alloys at room temperature with a stress ratio of -1. Take scanning electron microscope (SEM) images of the nickel-based alloy fracture surface, measure the equivalent radius a0 of the crack source of the nickel-based alloy, and calculate the stress intensity threshold value ΔK. th ;

[0035] The stress intensity threshold value ΔK th The calculation method is:

[0036]

[0037] Where HV is the Vickers hardness of the material, area is the crack source area, area=πa02 , a0 is the equivalent radius of the crack source.

[0038] S04: Substitute the relevant parameters into the ultra-high cycle fatigue life prediction formula of nickel-based alloy to obtain the ultra-high cycle fatigue life N of nickel-based alloy. i ;

[0039] The fatigue life N i The calculation method is:

[0040]

[0041] Among them, W s is the fracture energy, G is the shear modulus, Δσ is the fatigue stress amplitude, Δσ w is the fatigue limit and β is the life correction factor.

[0042] Preferably, the S03 further includes obtaining ultrasonic vibration fatigue test results, drawing a stress fatigue (SN) curve, and trying to obtain material parameters A and B to obtain a nickel-based alloy life correction factor β, where the calculation formula of the parameter β is:

[0043]

[0044] Where A and B are material parameters, which are tentatively obtained based on the results of ultrasonic vibration fatigue tests; Δσ is the fatigue stress amplitude; and a0 is the equivalent radius of the crack source.

[0045] A nickel-based alloy ultra-high cycle fatigue life prediction device, comprising:

[0046] Material shear modulus acquisition unit: used to conduct room temperature tensile tests on nickel-based alloys, draw the tensile curve of nickel-based alloys, and calculate the elastic modulus E of the room temperature material and the shear modulus G of the material based on the tensile curve;

[0047] Hardness testing unit: used to obtain the Vickers hardness HV of the material through hardness testing;

[0048] Micro-size acquisition unit: used to perform ultrasonic vibration fatigue test on nickel-based alloy at room temperature with a certain stress ratio of -1, take SEM images of nickel-based alloy fracture, measure the equivalent radius a0 of the crack source of nickel-based alloy, and calculate the stress intensity threshold value ΔK th ;

[0049]

[0050] Where HV is the Vickers hardness of the material, area is the crack source area, area=πa0 2 , a0 is the equivalent radius of the crack source.

[0051] Comprehensive calculation unit: Ultra-high cycle fatigue life prediction equation for nickel-based alloys:

[0052]

[0053] Among them, W s is the fracture energy, G is the shear modulus, Δσ is the fatigue stress amplitude, Δσ w is the fatigue limit and β is the life correction factor.

[0054] Substitute the relevant parameters into formula (b) to calculate the ultra-high cycle fatigue life N of nickel-based alloy i .

[0055] A correction device for ultra-high cycle fatigue life prediction of nickel-based alloys, comprising:

[0056] Material shear modulus acquisition unit: performs room temperature tensile test on nickel-based alloy, draws the tensile curve of nickel-based alloy, and calculates the elastic modulus E of the room temperature material and the shear modulus G of the material according to the tensile curve;

[0057] Hardness testing unit: performs hardness testing on nickel-based alloys to obtain the material's Vickers hardness HV;

[0058] Micro-size acquisition unit: Conduct ultrasonic vibration fatigue test on nickel-based alloy at room temperature with a certain stress ratio of -1, take SEM images of nickel-based alloy fracture, measure the equivalent radius a0 of the crack source of nickel-based alloy, and calculate the stress intensity threshold value ΔK th ;

[0059]

[0060] Where HV is the Vickers hardness of the material, area is the crack source area, area=πa0 2 , a0 is the equivalent radius of the crack source.

[0061] Comprehensive calculation unit: Ultra-high cycle fatigue life prediction equation for nickel-based alloys:

[0062]

[0063] Among them, W s is the fracture energy, G is the shear modulus, Δσ is the fatigue stress amplitude, Δσ w is the fatigue limit and β is the life correction factor.

[0064] Substitute the relevant parameters into formula (b) to calculate the ultra-high cycle fatigue life N of nickel-based alloy i .

[0065] Preferably, it also includes:

[0066] Life correction unit: Obtain the ultrasonic vibration fatigue test results, draw the stress fatigue (SN) curve, try to obtain the material parameters A and B, and obtain the nickel-based alloy life correction factor β. The calculation formula of β is:

[0067]

[0068] Where A and B are material parameters, which are tentatively obtained based on the results of ultrasonic vibration fatigue tests; Δσ is the fatigue stress amplitude; and a0 is the equivalent radius of the crack source.

[0069] The beneficial effects of the present invention are:

[0070] The present invention establishes an ultra-high cycle fatigue life prediction formula based on the microstructural parameters and crack source size of nickel-based alloys through tensile testing and ultrasonic vibration fatigue testing. Taking into account the key parameters of material performance parameters and crack source surface, a life correction factor β is constructed at the same time, making the measurement results more accurate and reasonable, and reducing errors.

[0071] Secondly, the measurement method is relatively simple, requiring only parameters related to the crack source surface to be measured, such as the equivalent radius of the crack source, without having to measure parameters related to the location depth. This reduces manual measurement errors and simplifies the method. Furthermore, this method utilizes ultrasonic vibration fatigue testing, which significantly reduces the time consumption compared to traditional fatigue testing, saving production time and costs. Overall, this method offers the advantages of simplicity, speed, and accuracy, and can effectively predict the ultra-high cycle fatigue life of high-temperature nickel-based alloys.

[0072] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0074] Figure 1 This is a flow chart of a method for predicting ultra-high cycle fatigue life of nickel-based alloys in the implementation of the present invention;

[0075] Figure 2 A nickel-based alloy tensile curve for a nickel-based alloy ultra-high cycle fatigue life prediction method in the implementation of the present invention;

[0076] Figure 3The number of the method for predicting ultra-high cycle fatigue life of nickel-based alloy in the present invention is No. 1, and the fatigue life is 1.20×10 7 SEM results of the ultrasonic vibration fatigue test fracture of the sample;

[0077] Figure 4 This is an SN diagram of ultrasonic vibration fatigue test results of a method for predicting ultra-high cycle fatigue life of a nickel-based alloy in the implementation of the present invention;

[0078] Figure 5 This is a diagram showing the life prediction results and test result verification of a method for predicting ultra-high cycle fatigue life of a nickel-based alloy in the implementation of the present invention;

[0079] Figure 6 This figure shows the life prediction results and correction result verification effect diagram of a nickel-based alloy ultra-high cycle fatigue life correction method in the implementation of the present invention. DETAILED DESCRIPTION

[0080] The following will clearly and completely describe the concept, specific structure and technical effects of the present invention in conjunction with the embodiments, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. In addition, all the connection / connection relationships mentioned in the text do not refer to the construction of a direct connection, but refer to the formation of a better connection structure by adding or reducing connection accessories according to the specific implementation situation. The various technical features in the invention can be combined interactively without conflicting with each other.

[0081] Example 1

[0082] The present invention discloses a method for predicting ultra-high cycle fatigue life of nickel-based alloys, comprising the following steps:

[0083] (1) Perform room temperature tensile test on nickel-based alloy and draw tensile curve of nickel-based alloy (such as Figure 2 As shown), and the elastic modulus E of the room temperature material is calculated based on the tensile curve, v is the Poisson's ratio of the nickel-based alloy; in this embodiment, E = 200 GPa, v = 0.3, and the shear modulus of the material is calculated as G = E / 2(1+v) = 76.9 GPa;

[0084] (2) Hardness test of nickel-based alloy was performed, and the Vickers hardness of the material was obtained as HV = 480;

[0085] (3) The nickel-based alloy was subjected to an ultrasonic vibration fatigue test at room temperature with a certain stress ratio of -1, and a scanning electron microscope (SEM) image of the nickel-based alloy fracture was taken. The vertical projection area of ​​the crack source is the cross-sectional projection area obtained by the scanning electron microscope (SEM), and area = πa0 2 The equivalent radius of the crack source a0 is obtained by conversion; the SEM results of the No.1 sample fracture are as follows Figure 3 As shown;

[0086] Steps (1), (2), and (3) do not represent the order of the steps, and steps (1), (2), and (3) can be used in a reversed order.

[0087] (4) Calculate the stress intensity threshold value ΔK by the formula th and fracture energy Ws;

[0088]

[0089]

[0090] The test and calculation results are shown in Table 1; where HV is the Vickers hardness of the material, area is the crack source area, and area = πa0 2 , a0 is the equivalent radius of the crack source.

[0091] Table 1 Fatigue test and calculation results

[0092]

[0093]

[0094] (5) Obtain the ultrasonic vibration fatigue test results and draw the SN curve. The results are as follows Figure 4 As shown; the fatigue limit Δσ of nickel-based alloy is calculated by the formula w :

[0095]

[0096] α=0.226+HV×10 -4

[0097] The value range of C is 1.43 to 1.56. In this embodiment, for the surface cracks or surface defects of nickel-based alloys, C=1.43.

[0098] (6) Obtain the actual life N of nickel-based alloy through ultrasonic vibration fatigue test results f (As shown in Table 1), try to obtain the material parameters A and B; here take A = 200, B = 620, substitute the material parameters A and B into the formula of the nickel-based alloy life correction coefficient β to obtain the nickel-based alloy life correction coefficient β.

[0099]

[0100] Where Δσ is the fatigue stress amplitude, and A and B are material parameters.

[0101] (7) Substituting the above related values ​​into the ultra-high cycle fatigue life prediction equation of nickel-based alloy, we can get N i :

[0102]

[0103] The present invention discloses a method for correcting the ultra-high cycle fatigue life of a nickel-based alloy, comprising the following steps:

[0104] (1) Perform room temperature tensile test on nickel-based alloy and draw tensile curve of nickel-based alloy (such as Figure 2 As shown), and the elastic modulus E of the room temperature material is calculated based on the tensile curve, v is the Poisson's ratio of the nickel-based alloy; in this embodiment, E = 200 GPa, v = 0.3, and the shear modulus of the material is calculated as G = E / 2(1+v) = 76.9 GPa;

[0105] (2) Hardness test of nickel-based alloy was performed, and the Vickers hardness of the material was obtained as HV = 480;

[0106] (3) The nickel-based alloy was subjected to an ultrasonic vibration fatigue test at room temperature with a certain stress ratio of -1, and a scanning electron microscope (SEM) image of the nickel-based alloy fracture was taken. The vertical projection area of ​​the crack source is the cross-sectional projection area obtained by the scanning electron microscope (SEM), and area = πa0 2 The equivalent radius of the crack source a0 is obtained by conversion; the SEM results of the No.1 sample fracture are as follows Figure 3 As shown;

[0107] Steps (1), (2), and (3) do not represent the order of the steps, and steps (1), (2), and (3) can be used in a reversed order.

[0108] (4) Calculate the stress intensity threshold value ΔK by the formula th and fracture energy Ws;

[0109]

[0110]

[0111] The test and calculation results are shown in Table 1; where HV is the Vickers hardness of the material, area is the crack source area, and area = πa0 2 , a0 is the equivalent radius of the crack source.

[0112] Table 1 Fatigue test and calculation results

[0113]

[0114] (5) Obtain the ultrasonic vibration fatigue test results and draw the SN curve. The results are as follows Figure 4 As shown; the fatigue limit Δσ of nickel-based alloy is calculated by the formula w :

[0115]

[0116] α=0.226+HV×10 -4

[0117] The value range of C is 1.43 to 1.56. In this embodiment, for surface cracks or surface defects of nickel-based alloys, C=1.43.

[0118] (6) Obtain the actual life N of nickel-based alloy through ultrasonic vibration fatigue test results f (As shown in Table 1), try to obtain the material parameters A and B; here A and B are initially set to 500 in the test results, and then substituted into N i In the formula (without β), the predicted lifespan is calculated, and the actual value is adjusted based on the error between the predicted lifespan and the actual lifespan (guaranteed to be within ±3 times the error). If the error exceeds ±3 times, a new value is required. If the error is within ±3 times, it can be substituted into the β formula to obtain β. (Three parameters are complex, and a single parameter will result in a large error and cannot guarantee the effect.)

[0119] Here, A=200, B=620 is the smallest error (as shown in Table 2, Table 3, Figure 6 As shown), the material parameters A and B are substituted into the nickel-based alloy life correction coefficient β formula to obtain the nickel-based alloy life correction coefficient β.

[0120]

[0121] Where Δσ is the fatigue stress amplitude, and A and B are material parameters.

[0122] Table 2 Comparison of actual fatigue life and corrected predicted life

[0123]

[0124] Table 3 Comparison of actual fatigue life and corrected predicted life error

[0125]

[0126]

[0127] (7) Substituting the above relevant values ​​into the ultra-high cycle fatigue life prediction equation of nickel-based alloy, the ultra-high cycle fatigue life of nickel-based alloy N is obtained. i :

[0128]

[0129] The present invention discloses a device for predicting ultra-high cycle fatigue life of nickel-based alloys, comprising:

[0130] Material shear modulus acquisition unit: used to conduct room temperature tensile tests on nickel-based alloys, draw the tensile curve of nickel-based alloys, and calculate the elastic modulus E of the room temperature material and the shear modulus G of the material based on the tensile curve;

[0131] Hardness testing unit: used to obtain the Vickers hardness HV of the material through hardness testing;

[0132] Micro-size acquisition unit: used to perform ultrasonic vibration fatigue test on nickel-based alloy at room temperature with a certain stress ratio of -1, take SEM images of nickel-based alloy fracture, measure the equivalent radius a0 of the crack source of nickel-based alloy, and calculate the stress intensity threshold value ΔK th ;

[0133]

[0134] Where HV is the Vickers hardness of the material, area is the crack source area, area=πa0 2 , a0 is the equivalent radius of the crack source.

[0135] Comprehensive calculation unit: Ultra-high cycle fatigue life prediction equation for nickel-based alloys:

[0136]

[0137] Among them, W s is the fracture energy, G is the shear modulus, Δσ is the fatigue stress amplitude, Δσ w is the fatigue limit and β is the life correction factor.

[0138] Substitute the relevant parameters into formula (b) to calculate the ultra-high cycle fatigue life N of nickel-based alloy i .

[0139] The present invention discloses a correction device for predicting ultra-high cycle fatigue life of nickel-based alloys, comprising:

[0140] Material shear modulus acquisition unit: performs room temperature tensile test on nickel-based alloy, draws the tensile curve of nickel-based alloy, and calculates the elastic modulus E of the room temperature material and the shear modulus G of the material according to the tensile curve;

[0141] Hardness testing unit: performs hardness testing on nickel-based alloys to obtain the material's Vickers hardness HV;

[0142] Micro-size acquisition unit: Conduct ultrasonic vibration fatigue test on nickel-based alloy at room temperature with a certain stress ratio of -1, take SEM images of nickel-based alloy fracture, measure the equivalent radius a0 of the crack source of nickel-based alloy, and calculate the stress intensity threshold value ΔK th ;

[0143]

[0144] Where HV is the Vickers hardness of the material, area is the crack source area, area=πa0 2 , a0 is the equivalent radius of the crack source.

[0145] Comprehensive calculation unit: Ultra-high cycle fatigue life prediction equation for nickel-based alloys:

[0146]

[0147] Among them, W s is the fracture energy, G is the shear modulus, Δσ is the fatigue stress amplitude, Δσ w is the fatigue limit and β is the life correction factor.

[0148] Substitute the relevant parameters into formula (b) to calculate the ultra-high cycle fatigue life N of nickel-based alloy i .

[0149] In this embodiment, it also includes:

[0150] Life correction unit: Obtain the ultrasonic vibration fatigue test results, draw the stress fatigue (SN) curve, try to obtain the material parameters A and B, and obtain the nickel-based alloy life correction factor β. The calculation formula of β is:

[0151]

[0152] Where A and B are material parameters, which are tentatively obtained based on the results of ultrasonic vibration fatigue tests; Δσ is the fatigue stress amplitude; and a0 is the equivalent radius of the crack source.

[0153] Comparison of predicted fatigue life and actual fatigue life Figure 5 As shown in the figure, the predicted lifespan is basically within the ±2 error bar, with high accuracy. This shows that in the ultra-high cycle range, the lifespan prediction model constructed by material performance parameters and micro-size is effective and has a high accuracy rate.

[0154] Through tensile testing and ultrasonic vibration fatigue testing, a very high cycle fatigue life prediction formula for nickel-based alloys based on microstructural parameters and crack source size was established. Taking into account key parameters of material properties and crack source surface, a life correction factor β was constructed. Two material parameters, A and B, were used to simplify the calculation while ensuring accuracy.

[0155] Secondly, the measurement method is relatively simple, requiring only parameters related to the crack source surface, such as the equivalent radius of the crack source, without the need to measure parameters related to the location depth. This reduces manual measurement errors and simplifies the method. Furthermore, this method utilizes ultrasonic vibration fatigue testing, which significantly reduces the time consumption compared to traditional fatigue testing, saving production time and costs. Overall, this method offers the advantages of simplicity, speed, and accuracy, and can effectively predict the ultra-high cycle fatigue life of high-temperature nickel-based alloys.

[0156] The preferred embodiments of the present invention are described in detail above, but the invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A method for predicting ultra-high cycle fatigue life of nickel-based alloys, characterized in that: The following steps are involved: S01: Perform room temperature tensile tests on nickel-based alloys, draw tensile curves of nickel-based alloys, and calculate the elastic modulus of the material at room temperature based on the tensile curves E , calculate the material shear modulus G ; S02: Perform hardness test on nickel-based alloy to obtain the Vickers hardness of the material HV ; S03: Conduct ultrasonic vibration fatigue tests on nickel-based alloys at room temperature with a stress ratio of -1, take scanning electron microscope images of the nickel-based alloy fracture surface, and calculate the equivalent radius of the crack source of the nickel-based alloy. a 0, the stress intensity threshold value Δ is calculated K th ; S04: Substitute the relevant parameters into the ultra-high cycle fatigue life prediction formula of nickel-based alloy to obtain the ultra-high cycle fatigue life of nickel-based alloy N i ; The stress intensity threshold value Δ K th The calculation method is: (a) in HV is the Vickers hardness of the material, area is the crack source area, area = π a 0 2 , a 0 is the equivalent radius of the crack source; The fatigue life N i The calculation method is: (b) in, W s is the fracture energy, G is the shear modulus, Δ σ is the fatigue stress amplitude, Δ σ w is the fatigue limit, β is the life correction factor; The S03 also includes obtaining ultrasonic vibration fatigue test results, drawing stress fatigue curves, and trying to obtain material parameters. A and B， Material parameters A and B Substitute the nickel-based alloy life correction factor β In the formula, the nickel-based alloy life correction factor is obtained β , β The calculation formula is: (c) in, A and B is a material parameter, which is obtained based on the results of ultrasonic vibration fatigue test; Δ σ is the fatigue stress amplitude; a 0 is the equivalent radius of the crack source; The S03 further includes substituting relevant parameters into the calculation formula (d), (d) Obtaining the fracture energy of nickel-based alloys W s .

2. The method for predicting ultra-high cycle fatigue life of nickel-based alloys according to claim 1, characterized in that: Shear modulus of the material G The calculation formula is: (g) in v is the Poisson's ratio of nickel-based alloy.

3. A device for predicting ultra-high cycle fatigue life of nickel-based alloys, characterized in that: include: Material shear modulus acquisition unit: nickel-based alloys are subjected to room temperature tensile tests, the tensile curve of nickel-based alloys is drawn, and the elastic modulus of the material at room temperature is calculated based on the tensile curve E , calculate the material shear modulus G ; Hardness testing unit: used to obtain the Vickers hardness of materials through hardness testing HV ; Micro-size acquisition unit: used to perform ultrasonic vibration fatigue test on nickel-based alloy at room temperature with a certain stress ratio of -1, take fracture pictures of nickel-based alloy, and calculate the equivalent radius of crack source of nickel-based alloy. a 0, the stress intensity threshold value Δ is calculated K th ; (a) in HV is the Vickers hardness of the material, area is the crack source area, area = π a 0 2 , a 0 is the equivalent radius of the crack source; Comprehensive calculation unit: Ultra-high cycle fatigue life prediction equation for nickel-based alloys: (b) in, W s is the fracture energy, G is the shear modulus, Δ σ is the fatigue stress amplitude, Δ σ w is the fatigue limit, β is the life correction factor; Substitute the relevant parameters into formula (b) to calculate the ultra-high cycle fatigue life of nickel-based alloy; Also includes: Life correction unit, used to obtain ultrasonic vibration fatigue test results, draw stress fatigue curves, and try to obtain material parameters A and B , the material parameters A and B Substitute the nickel-based alloy life correction factor β In the formula, the nickel-based alloy life correction factor is obtained β , β The calculation formula is: (c) in, A and B is a material parameter, which is obtained based on the results of ultrasonic vibration fatigue test; Δ σ is the fatigue stress amplitude; a 0 is the equivalent radius of the crack source; Fatigue limit calculation unit, used to substitute relevant parameters into the calculation formula (d), (d) Obtaining the fracture energy of nickel-based alloys W s .

Images