CN114252471B - Rapid prediction method for high-temperature fatigue performance of nickel-based superalloy small-angle grain boundary - Google Patents
Rapid prediction method for high-temperature fatigue performance of nickel-based superalloy small-angle grain boundary Download PDFInfo
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Abstract
The invention discloses a rapid prediction method for high-temperature fatigue performance of a nickel-based superalloy small-angle grain boundary, belonging to the technical field of performance test of metal materials. The method comprises the following steps: (1) Determining the grain boundary orientation difference of the bicrystals prepared by the same process through microscopic experiments; (2) Selecting more than 3 kinds of grain boundary orientation difference bicrystals and determining the change rule of the linear density of grain boundary defects along with the orientation difference; (2) The twin-crystal fatigue life N is obtained through a high-temperature fatigue experiment f And fatigue strength sigma FS The method comprises the steps of carrying out a first treatment on the surface of the (3) Obtaining key parameters of the material through fatigue strength/life data fitting; (4) And quantifying a fatigue strength/life prediction model by using key parameters and predicting the high-temperature fatigue performance of other grain boundary poor orientation. According to the invention, the high-temperature fatigue performance prediction of the nickel-based superalloy containing the small-angle grain boundary with poor random grain boundary orientation can be realized by only testing the high-temperature fatigue performance of a small amount of samples. The method can effectively reduce fatigue experiments in the process of engineering material development and evaluation, and realize efficient prediction of the fatigue performance of the material.
Description
Technical Field
The invention relates to the technical field of performance test of metal materials, in particular to a rapid prediction method for high-temperature fatigue performance of a nickel-based superalloy small-angle grain boundary.
Background
Failure of structural materials due to fatigue occupies an important place in the field of structural fatigue failure. Fatigue properties (including fatigue strength, fatigue life, etc.) are fundamental properties of structural materials, which affect not only other dynamic mechanical properties, such as creep strength, crack growth rate, etc., but also directly the service properties of the materials when they are ultimately used. In view of the importance of fatigue properties, on the one hand, assessment of fatigue properties during development of engineering materials is indispensable, and on the other hand, modification and optimization of the material organization is often also aimed at improvement of fatigue strength and fatigue/life. The nickel-based single crystal superalloy is widely applied to turbine blades of aeroengines by virtue of excellent high-temperature mechanical properties, and is served in a high-temperature environment. However, in the directional solidification of the nickel-base single crystal superalloy, some directional solidification defects may inevitably occur due to the complexity of alloy composition and process. Among them, small angle grain boundaries, which are a common defect, have an important influence on the performance and service behavior of the nickel-based single crystal alloy. The grain boundary orientation difference, i.e., the angle of relative rotation between two grains about an axis of rotation, is an intrinsic parameter describing the grain boundary morphology and structure of a metallic material. Thus, the service performance (such as fatigue strength/life) of nickel-base superalloys containing small angle grain boundaries must be closely related to poor grain boundary orientation. In conclusion, the nickel-based superalloy high-temperature fatigue performance based on poor grain boundary orientation is accurately evaluated, and plays an important role in research and development and application of engineering materials.
It is well known that the most direct and efficient way to obtain fatigue performance is to prepare samples according to national standards and to conduct fatigue experiments. The fatigue experiment is complex, and in view of the lack of related theory, a great amount of fatigue experiments and related process repeated adjustment are often required to be carried out in the process of developing, designing and evaluating the materials, so that the difficulty and cost of developing and evaluating the materials are greatly increased. Therefore, if the relationship between the fatigue performance and the grain boundary orientation and between the material composition and the treatment process can be established through developing a related theoretical model, the fatigue performance can be rapidly predicted, and the method has very important significance in the aspects of engineering material research and development, design and evaluation and in the aspect of subject theoretical construction.
At present, in the aspect of fatigue performance prediction, both a theoretical model and a technical means are very deficient. In terms of theoretical studies, although earlier studies have proposed many metal material prediction theories, these theories are basically a unique description of the fatigue damage process, and the relevant parameters of the theories lack a clear physical meaning. Therefore, these theories only help to understand the fatigue damage process qualitatively, but cannot be directly used to establish quantitative relationships between fatigue performance and relevant component parameters, and cannot be used to predict fatigue performance. In addition, the prior theoretical work has hardly focused on the essential influence of the poor grain boundary orientation on the fatigue damage process of the metal material, and the quantitative relation between the poor grain boundary orientation and the fatigue performance of the metal material has not been studied and proposed yet. In engineering applications, there are some common relationships describing fatigue curves, such as the common Basquin and Coffin-Manson formulas. However, these relational formulas are essentially empirical formulas describing the fatigue behavior of metallic materials, essentially but not all fitting to experimental curves. The physical meaning of the parameters in these formulas is not clear due to lack of connection with microscopic mechanisms, and these parameters hardly reflect the effect of poor grain boundary orientation. Therefore, none of these descriptive formulas in principle have the ability to predict nickel-base superalloy high temperature fatigue performance, especially based on low angle grain boundary containing nickel-base superalloy high temperature fatigue performance with poor grain boundary orientation.
In summary, the method for establishing a quantitative model of the nickel-based superalloy small-angle grain boundary high-temperature fatigue performance and realizing the rapid prediction of the nickel-based superalloy high-temperature fatigue performance based on poor grain boundary orientation has important engineering and theoretical significance, but no suitable theoretical basis and technical means exist at present.
Disclosure of Invention
The invention aims to provide a rapid prediction method for the high-temperature fatigue performance of a nickel-based superalloy small-angle grain boundary, which realizes rapid prediction of the high-temperature fatigue strength/life by establishing a quantitative relation among the high-temperature fatigue strength, the high-temperature fatigue life and the grain boundary orientation difference, thereby greatly reducing the experimental quantity required to be developed in material development, design and evaluation optimization and grain boundary orientation difference optimization.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a fast prediction method of nickel-based superalloy small angle grain boundary high temperature fatigue performance is that high temperature fatigue experiments are carried out on more than 3 kinds of grain boundary orientation difference nickel-based superalloy bi-crystal materials prepared by the same process, and the high temperature fatigue performance of any grain boundary orientation difference nickel-based superalloy bi-crystal material prepared by other same process is predicted according to the obtained experimental data; the method specifically comprises the following steps:
(1) Selecting more than 3 groups of bimorph materials prepared by the same process with different grain boundary orientation differences, and determining the change rule of the linear density of the grain boundary defects along with the grain boundary orientation differences;
(2) Testing the fatigue performance of the prepared material through a high-temperature fatigue experiment;
(3) Obtaining key parameters (A, n and β) of the prepared material by fitting fatigue strength/life data;
(4) And (3) according to the key parameters obtained in the step (4), carrying out high-temperature fatigue performance prediction of the bicrystal material prepared by other same process under any grain boundary orientation difference by utilizing a quantified bicrystal high-temperature fatigue strength/life prediction model.
In the step (1), the grain boundary is observed through microscopic experiments, the grain boundary orientation difference is determined, the double crystals, especially the grain boundary region, are required to maintain the original morphology (before deformation), the double crystals are gradually focused on the grain boundary region from low power to high power during observation, and the double crystals are observed by microscopic equipment with a grain boundary orientation analysis function.
In the step (1), the same process refers to a preparation process with unchanged material components (element proportions) and technological parameters in material preparation. The different grain boundary orientation differences are different grain boundary orientation differences of the prepared double crystal grain boundary by changing the relative rotation angle between the same orientations of seed crystals in the preparation of the double crystal material (the selection of a fatigue test sample is carried out under the different grain boundary orientation differences of the same process, and more than 3 double crystal materials with the grain boundary orientation differences of less than 15 degrees and larger differences are selected to carry out the fatigue performance test of the step (2); the grain boundary precipitation phase line density f is considered to be changed in proportion to the grain boundary orientation difference theta, the proportionality coefficient is 1/k, and the proportionality coefficient can be determined by fitting the situation that the grain boundary defects (micropores, carbides and the like) under different grain boundary orientation differences are changed along with the orientation differences.
In the step (3), the key parameters of the prepared material obtained by fitting fatigue strength/life data are as follows: fitting the fatigue strength data of more than 3 groups obtained in the step (2) by using a formula (1) to obtain corresponding intrinsic parameters n andand substituting the value of n into the formula (2), and fitting the plurality of groups (more than 3 groups) of fatigue life data obtained in the step (2) by using the formula (2) to obtain a plurality of groups (more than 3 groups) of values of parameters A and beta, wherein the average value of A and beta is the intrinsic A value and the intrinsic beta value related to the bicrystal component.
Wherein: sigma (sigma) FS Is fatigue strength;Θ is the work hardening rate, b is the modulus of the dislocation Berth vector, l is the average distance of dislocation motion, ρ c For fatigue damage dislocation density tolerance, a may be defined as the strengthening coefficient of the material; n is the sensitivity index of the fatigue damage of the material to the grain boundary defect; beta is the dislocation density conversion rate of fatigue damage; sigma (sigma) max Is the maximum stress of the fatigue test.
In the step (4), the quantitative twin-crystal fatigue high-temperature strength/life prediction model can be obtained by obtaining the key parameters, namely intrinsic parameters A, n and beta, in the step (3) and substituting the parameters into formulas (1) and (2), so that the high-temperature fatigue strength/life of any twin-crystal material with poor grain boundary orientation under the same technological conditions of specific components can be predicted.
The invention has the following advantages and beneficial effects:
1. the method of the invention uses a fatigue experiment under a small amount of grain boundary orientation differences as a basic guiding idea to predict the fatigue performance under other grain boundary orientation differences. By establishing the intrinsic relation among the fatigue strength, the fatigue life and the grain boundary orientation difference, the high-temperature fatigue strength/life prediction of the nickel-based superalloy bicrystal material with any grain boundary orientation difference under all the same treatment processes can be realized by only testing the high-temperature fatigue performance of a sample with a small amount of grain boundary orientation difference. By utilizing the method, fatigue experiments in the process of engineering material development, evaluation and selection can be effectively reduced, the traditional anti-fatigue design mode of repeated testing is hopeful to be replaced, and the efficient prediction of fatigue performance is realized.
2. The invention establishes a brand new high-temperature alloy fatigue damage theoretical model based on grain boundary orientation difference, namely a fatigue deformation dislocation accumulation model based on dislocation accumulation and fatigue damage related theory and combines a system verification experiment, and the fatigue strength, the fatigue life and the grain boundary orientation difference intrinsic relation are established for the first time. By using the model, fatigue performance prediction of the nickel-based superalloy bi-crystal material with poor grain boundary orientation under all similar treatment processes can be realized only by a small amount of fatigue tests. In addition, by combining a material performance database, quantitative prediction of fatigue performance corresponding to any grain boundary orientation difference under various treatment processes of various bicrystal materials is expected to be realized. The method can effectively reduce a large number of experimental tests in the process of developing, evaluating and optimizing engineering materials containing grain boundaries, and truly realize the theoretical efficient prediction of the material performance.
3. At present, the tissue structure and performance optimization of the grain boundary-containing material mainly depend on a large number of repeated trial and error experiments, wherein the repeated experiments comprise repeated component adjustment, process adjustment, grain boundary structure adjustment and fatigue experiment, and the period and cost of material development are greatly increased. In practice, the problem of comparison of fatigue performance among grain boundary-containing materials with the same basic components and the same treatment process is frequently faced in the development, evaluation and selection processes of the grain boundary-containing materials, the main parameters of the formula related in the invention can be regarded as constants for different grain boundary orientation differences, and specific numerical values can be determined only by a small amount of fatigue tests, so that the relationship between the fatigue performance and the grain boundary orientation differences of the series of materials is obtained, and a large amount of grain boundary characteristic fumbling and experimental test work is omitted. The method not only realizes the mutual correlation of fatigue properties among materials in different states, but also successfully realizes the rapid prediction of fatigue properties based on poor grain boundary orientation, and saves a large amount of test and evaluation cost.
Drawings
FIG. 1 is a flow chart for rapidly predicting the high-temperature fatigue performance of the nickel-base superalloy material of the present invention.
Fig. 2 is a schematic diagram of grain boundary damage "short plate effect".
FIG. 3 is a model of the validation of fatigue deformation dislocation volume for different nickel-base superalloy materials; wherein: (a) A fatigue data verification model of the high-temperature alloy DD10 under the maximum stress of 380 MPa; (b) Fatigue data verification models of the high-temperature alloy DD5 blade under two maximum stresses (400 MPa and 500 MPa); (c) Fatigue data verification models of the superalloy DD5 under two maximum stresses (350 MPa and 400 MPa); (d) And comparing the fatigue strength measured by the DD5 experiment of the high-temperature alloy with the predicted fatigue strength of the model.
FIG. 4 is a quantitative prediction of fatigue performance of a nickel-base superalloy DD5 for a particular composition and process; wherein: (a) The fatigue strength of the DD5 is a prediction result of the change rule of the fatigue strength of the DD5 along with the grain boundary orientation difference; (b) And predicting the fatigue life of the DD5 after three-stage aging treatment along with the grain boundary orientation difference and the maximum stress change rule.
FIG. 5 is a fatigue curve and a fatigue strength curve of a nickel-base superalloy DD 5; wherein: (a) a fatigue curve; (b) fatigue strength curve.
FIG. 6 is a key parameter fit in example 1; wherein: (a) Obtaining key parameters n and parameter combinations for fitting fatigue strength data(b) Fitting the fatigue life data to obtain the key parameters A and beta.
FIG. 7 is a graph showing the predicted fatigue performance of the DD5 nickel-base superalloy (red spheres in the graph represent experimental data); wherein: (a) The fatigue strength prediction result is obtained under different grain boundary orientations; (b) The fatigue life prediction results are obtained under different grain boundary orientations and maximum stress.
Detailed Description
The present invention will be described in detail below with reference to the drawings and examples.
The invention relates to a rapid prediction method for high-temperature fatigue performance of a nickel-based superalloy small-angle grain boundary, which is shown in a figure 1 in the operation flow, and comprises the following four steps: (1) Selecting more than 3 groups of bimorph materials with different quality orientation differences (determining the change rule of the grain boundary orientation differences and the grain boundary defect line density along with the grain boundary orientation differences); (2) testing the high temperature fatigue properties of each group of materials; (3) fitting fatigue data to obtain key parameters; (4) predicting high-temperature fatigue performance;
the technical proposal is as follows:
the invention adopts a fatigue deformation dislocation product model of fatigue performance to realize prediction, the name is derived from the gradual dislocation product at the grain boundary during fatigue deformation, and the basic form of the formula is as follows:
in the formulas (1) - (2), a and β are material composition parameters, the basic composition is defined, the two parameters are constants, n is a process parameter, the process type is defined (such as rolling, pre-deformation, heat treatment, etc.), and n is defined. These three parameters can be obtained in practice by more than 3 fatigue tests. After the parameter values are determined, the fatigue strength and fatigue life for a given grain boundary orientation difference can be predicted according to the formulas (1) and (2), thereby achieving efficient prediction of structure-performance.
The theoretical basis of the method is a fatigue deformation dislocation product model reflecting the physical process of fatigue damage: d (D) i ＝1/N f ＝(ρ i /ρ c ) β The main inferences include: relationship between fatigue strength and grain boundary orientation differenceRelationship between fatigue life and grain boundary orientation difference>
The scientific principle is as follows:
the fatigue deformation dislocation product model adopted in the method is strictly derived based on related knowledge, and is verified by a large number of system experiments, and the main derivation links are as follows:
first, by movable dislocation density and slip system actuation analysis, the grain boundary dislocation bulk density was deduced: wherein ρ is θ The bulk density of the motion dislocation caused by the grain boundary structure per se in each load cycle; ρ d The bulk density of the dislocation of the motion caused by the grain boundary defects in each load cycle; sigma (sigma) max Is the maximum stress during the load cycle; omega shape 0 The expression of the corresponding Schmitt factor of the slip system representing the bicrystal basis injury is omega 0 ＝V A Ω A +V B Ω B ，V A And V B The volume fraction of single crystal grains at two sides of the grain boundary, omega A And omega B The Schmitt factors of a single grain start slip system at two sides of the grain boundary respectively; ΔΩ is the difference between the schmitt factors of the single-grain start slip system on both sides of the grain boundary; Θ is the work hardening rate; b is the modulus of the dislocation berkovich vector; l is the average distance of dislocation movement.
Secondly, by combining experimental rules and analysis of the characteristics of the grain boundary damage, a 'short plate effect' of the grain boundary defect on the fatigue damage of the grain boundary is provided:wherein ρ is i The total amount of dislocation volume caused by grain boundaries during each load cycle; n is the sensitivity index of the fatigue damage of the material to the grain boundary defect, namely the degree reflecting the short-plate effect; f is the linear density of grain boundary defects. The short plate effect is schematically shown in figure 2.
Then, according to the idea that dislocation accumulation causes fatigue damage accumulation and leads to failure fracture, a fatigue process based on dislocation accumulation density is proposed: d (D) i ＝1/N f ＝(ρ i /ρ c ) β . Wherein D is i The ratio of damage in each load cycle is averaged; ρ c The volume density of grain boundary dislocation, i.e., the tolerance of the dislocation density of fatigue damage, required for the material to fail in fatigue; beta is the fatigue damage dislocation density conversion.
Based on the dislocation volume density related to the grain boundary orientation difference, the 'short slab effect' of the grain boundary fatigue damage and the fatigue process based on the dislocation volume density, a reasonable and convenient fatigue deformation dislocation volume model is deduced:wherein (1)>N f ＝10 7 The corresponding maximum stress is regarded as fatigue strength sigma FS The setting has engineering significance on the premise of meeting theoretical deduction. The basic expression of the dislocation product model can be used for giving the corresponding relation between any grain boundary orientation difference and the fatigue property (fatigue strength and fatigue life) of the bimorph material under specific components and process conditions.
The technical effects are as follows: the fatigue deformation dislocation product model is well matched with the experimental result. Although the fatigue deformation dislocation product model is derived based on a microscopic deformation mechanism, whether the model is scientific and practical must be verified through experiments. Compared with various fitting models which are proposed in the past, the dislocation space model not only accurately gives quantitative relations of poor orientation, components, process parameters and fatigue performance, but also predicts fatigue ranges to span low-cycle fatigue and high-cycle fatigue, and simultaneously shows sensitivity of fatigue damage to grain boundary defects, so that the dislocation space model may be more advantageous in terms of accuracy and applicability. In order to fully test the effect of the model in predicting the fatigue performance of the grain boundary-containing material, a plurality of nickel-based superalloy DD10 samples, nickel-based superalloy DD5 samples and nickel-based superalloy DD5 blade samples with different grain boundary orientations are selected and prepared. And respectively carrying out fatigue tests on the samples, then predicting fatigue performance by using a dislocation-stuffing model, and finally comparing test results with predicted results, wherein the results are shown in figure 3. It can be seen that the experimental result is well matched with the fatigue deformation dislocation accumulation model prediction result, the error between the prediction value and the actual measurement value is small, and the sensitivity of the fatigue damage to the grain boundary orientation difference or the grain boundary defect is also disclosed, so that the rationality of the model is proved, and the model can realize the accurate prediction of the fatigue strength and the fatigue life of the grain boundary-containing material.
(2) The technical effects are as follows: nickel-base superalloy high-temperature fatigue properties under different grain boundary orientations and different stresses of grain boundary-containing materials under specific component & processCan be predicted quantitatively. There are three parameters A, n and β in the fatigue deformation dislocation product model, where a=Θbl ρ c ，Θ、b、l、ρ c N and β are related to the material composition, which is quantitatively related to the composition & process. Thus, parameters A, n and β are intrinsic parameters of the composition & process decision, and A, n and β for materials under different conditions can be obtained by computational or experimental methods. The relationship between the grain boundary orientation difference, stress and high-temperature fatigue property under the specific composition & process is shown in FIG. 4. It can be seen that for specific components & processes, the quality orientation difference and stress are given, the corresponding high-temperature fatigue life can be predicted by using our model, and the corresponding high-temperature fatigue strength of the specific grain orientation difference can be obtained by using the change conditions of the fatigue life and stress.
Example 1:
the embodiment is a fatigue performance prediction method for the nickel-based superalloy DD5 containing the small-angle grain boundary, and the specific process is as follows:
(1) Materials:
the preparation process of the 7-grain boundary orientation difference nickel-based superalloy DD5 bicrystal (grain boundary orientation difference is set to 0 degree, 2 degree, 4 degree, 6 degree, 8 degree, 10 degree and 12 degree, 0 degree bicrystal is single crystal, and each preset orientation difference bicrystal is prepared by a plurality of steps of: placing seed crystal pairs according to the set orientation difference, carrying out directional solidification and casting on the twin crystals, and carrying out three-stage aging heat treatment (1300 ℃/2h/AC+1120 ℃/4h/AC+1080 ℃/4h/AC+900 ℃/4 h/AC).
(2) The flow is as follows:
step 1: the grain boundary orientation difference theta is determined through microscopic experiments, 7 groups of materials with larger and more reasonable grain boundary orientation difference (the grain boundary orientation difference is 0 degree, 2.60 degree, 4.92 degree, 6.88 degree, 8.49 degree, 10.31 degree and 13.23 degree respectively), the change rule of the grain boundary defect linear density f along with the grain boundary orientation difference is f=theta/21.64 degree is determined to prepare a uniform-size platy fatigue sample (the diameter of a sample gauge length part is 3mm, the length of a gauge length section is 10 mm), and then a high-temperature (980 ℃) stress fatigue experiment is carried out to obtain the fatigue life and the fatigue strength under 7 grain boundary orientation differences, as shown in fig. 5.
Step 2: and (5) fitting key parameters. Fitting the fatigue strength data and the fatigue life data by using a formula 1 and a formula 2 respectively to obtain three important parameters: the strengthening coefficient A, the index n of sensitivity of fatigue damage to grain boundary defects and the dislocation density conversion rate beta of the fatigue damage are shown in figure 6.
Step 3: fatigue performance is predicted. The fatigue properties of the current composition and the rest of the conditions (the rest of the grain boundary orientations are poor) are predicted according to the formula (1) and the formula (2), respectively, using the parameters obtained by fitting in the step 2, and the results are shown as a curve in fig. 7. It can be seen that under this composition and process conditions, with the aid of the fatigue damage dislocation volume model, the fatigue strength of the material can be predicted by a given grain boundary orientation difference, and the fatigue life of the material can be predicted by a given stress and grain boundary orientation difference.
Claims (5)
1. A rapid prediction method for high-temperature fatigue performance of a nickel-based superalloy small-angle grain boundary is characterized by comprising the following steps: according to the method, fatigue experiments are carried out on different grain boundary orientation difference nickel-based superalloy bi-crystal materials prepared by the same process, and fatigue performance of any grain boundary orientation difference nickel-based superalloy bi-crystal material prepared by other same processes is predicted according to obtained experimental data; the method specifically comprises the following steps:
(1) Selecting more than 3 groups of bimorph materials prepared by the same process with different grain boundary orientation differences, and determining the change rule of the linear density of the grain boundary defects along with the grain boundary orientation differences; the grain boundary phase line density f is considered to be changed in proportion to the grain boundary orientation difference theta, the proportionality coefficient is 1/k, and the proportionality coefficient can be determined by fitting the situation that the grain boundary defects under different grain boundary orientation differences are changed along with the orientation difference;
(2) Testing the fatigue performance of the prepared material through a high-temperature fatigue experiment;
(3) Obtaining key parameters A, n and beta of the prepared material by fitting fatigue strength/life data;
(4) According to the key parameters obtained in the step (3), carrying out high-temperature fatigue performance prediction of the nickel-based superalloy bi-crystal material under any grain boundary orientation difference by utilizing a quantified bi-crystal high-temperature fatigue strength/life prediction model through other same processes;
in step (3), the pass fatigue strength/life dataThe key parameters for fitting to obtain the prepared material are: fitting the plurality of groups of fatigue strength data obtained in the step (2) by using a formula (1) to obtain corresponding intrinsic parameters n and A/10 7/β Substituting the value of n into a formula (2), and fitting the plurality of groups of fatigue life data obtained in the step (2) by using the formula (2) to obtain a plurality of groups of values of parameters A and beta, wherein the average value of A and beta is the intrinsic A value and the intrinsic beta value related to the bicrystal component;
wherein: sigma (sigma) FS Is fatigue strength;Θ is the work hardening rate, b is the modulus of the dislocation Boehringer's vector, I is the average distance of dislocation motion, ρ c For fatigue damage dislocation density tolerance, a may be defined as the strengthening coefficient of the material; n is the sensitivity index of the fatigue damage of the material to the grain boundary defect; beta is the dislocation density conversion rate of fatigue damage; delta max Maximum stress for fatigue test;
in the step (4), the quantitative twin-crystal high-temperature fatigue strength/life prediction model can be obtained by obtaining the key parameters, namely intrinsic parameters A, n and beta, in the step (3) and substituting the parameters into formulas (1) and (2), so that the high-temperature fatigue strength/life of any grain boundary orientation difference twin-crystal material under the same process conditions of specific components can be predicted.
2. The method for rapidly predicting the low-angle grain boundary high-temperature fatigue performance of the nickel-based superalloy according to claim 1, wherein the method comprises the following steps: in the step (1), the grain boundary is observed through microscopic experiments, the grain boundary orientation difference is determined, the original morphology before deformation is required to be kept for the twinning during observation, the twinning is gradually focused on the grain boundary region from low power to high power during observation, and microscopic equipment with a grain boundary orientation analysis function is adopted for observing the twinning.
3. The method for rapidly predicting the low-angle grain boundary high-temperature fatigue performance of the nickel-based superalloy according to claim 1, wherein the method comprises the following steps: in the step (1), the grain boundary is observed through microscopic experiments, the grain boundary orientation difference is determined, the original appearance of the grain boundary region before deformation is required to be maintained during observation, the grain boundary region is gradually focused from low power to high power during observation, and the bicrystal is observed by adopting microscopic equipment with a grain boundary orientation analysis function.
4. The method for rapidly predicting the low-angle grain boundary high-temperature fatigue performance of the nickel-based superalloy according to claim 1, wherein the method comprises the following steps: in the step (1), the same process refers to a preparation process in which the material components and the process parameters are not changed in the preparation of the material; the different grain boundary orientation differences are different grain boundary orientation differences of the prepared double crystal grain boundary by changing the relative rotation angle between the same orientations of seed crystals in the preparation of the double crystal material, wherein the selection of fatigue test samples is carried out under the different grain boundary orientation differences of the same process, and more than 3 double crystal materials with the grain boundary orientation differences smaller than 15 degrees and larger differences are selected for the fatigue performance test of the step (2).
5. The method for rapidly predicting the low-angle grain boundary high-temperature fatigue performance of the nickel-based superalloy according to claim 1, wherein the method comprises the following steps: the method is suitable for various face-centered cubic metal materials, and the applicable process is one or a combination of several of various rolling, pre-deformation and heat treatment processes.
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