Prediction method of creep mechanical properties of precipitation hardened nickel-based alloys based on microstructure

Abstract

The invention discloses a method for predicting creep mechanical properties of a precipitation-hardened nickel-based alloy based on microstructure, which relates to the technical field of performance prediction and includes the following steps: S1, obtaining characteristic parameters of the nickel-based alloy; S2, constructing a creep performance prediction model; S3, optimizing the creep performance prediction model using the characteristic parameters of the nickel-based alloy; S4, completing performance prediction using the optimized creep performance prediction model. The invention is based on a model of the initial microstructure, and can predict the creep properties of an unknown material by artificially inputting different microscopic parameters, so as to obtain the microstructure characteristics that a material with good creep performance should have.

Description

Technical Field

[0001] The invention relates to the technical field of performance prediction, and in particular to a method for predicting creep mechanical properties of a precipitation-hardened nickel-based alloy based on microstructure. Background Art

[0002] Nickel-based alloys are widely used in hot-end engine components, such as turbine disks and blades, due to their excellent high-temperature mechanical properties. During high-temperature service, creep will occur when the material stress or strain state remains unchanged. Its size will slowly elongate due to creep, and once creep fracture occurs in engine components, serious consequences will occur. Establishing creep properties based on microstructural evolution to evaluate its service reliability and provide a reference for microstructural regulation in the material development process is the key to further improving its service performance, and has important strategic significance for the defense industry and other fields.

[0003] At present, the microscopic models mainly focus on the interaction between dislocations and precipitations, and the continuous damage mechanics method is often used to consider the microscopic damage in the creep process, such as precipitation coarsening and creep voids. However, these models only consider part of the microscopic evolution mechanism of the alloy in the process, and are only applicable to specific creep conditions. They cannot simulate the creep properties of the alloy at different temperatures and stresses and their corresponding different microscopic evolution mechanisms. For example, at intermediate temperatures, stacking fault shear is dominant, while at high temperatures, dislocation slip and creep voids are dominant. In addition, the existing models are unable to predict the evolution of the microstructure during the creep process. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a method for predicting creep mechanical properties of precipitation hardened nickel-based alloy based on microstructure.

[0005] The technical solution of the present invention is: a method for predicting creep mechanical properties of precipitation hardened nickel-based alloy based on microstructure comprises the following steps:

[0006] S1. Obtain characteristic parameters of nickel-based alloy;

[0007] S2. Using the creep strain rate caused by dislocation slip and the creep strain rate caused by stacking fault shear, a creep performance prediction model is constructed;

[0008] S3. Optimizing the creep performance prediction model using characteristic parameters of nickel-based alloys;

[0009] S4. Use the optimized creep performance prediction model to complete performance prediction.

[0010] Furthermore, in S1, the characteristic parameters of the nickel-based alloy include shear modulus, Poisson's ratio, Burgers vector, dislocation density, grain size, precipitate phase size and precipitate phase volume fraction.

[0011] Furthermore, S2 includes the following sub-steps:

[0012] S21. Calculate the creep strain rate caused by dislocation slip;

[0013] S22, determining an evolution rate equation of stacking fault density according to the initial length of the stacking fault shear strengthening phase, and calculating the creep strain rate caused by stacking fault shear using the evolution rate equation of stacking fault density;

[0014] S23. Calculate creep damage of creep holes;

[0015] S24. Calculate creep damage of carbide coarsening;

[0016] S25. A creep performance prediction model is constructed based on the creep strain rate caused by dislocation slip, the creep strain rate caused by stacking fault shear, the creep damage of creep holes, and the creep damage of carbide coarsening.

[0017] Furthermore, in S21, the creep strain rate caused by dislocation slip is The calculation formula is:

[0018] ;

[0019] In the formula, ρ m represents movable dislocation, b represents the Burgers vector of nickel-based high-temperature alloy, v g represents the dislocation sliding velocity, and M represents the Taylor factor.

[0020] Furthermore, in S22, the evolution rate equation of the stacking fault density is The expression is:

[0021] ;

[0022] In the formula, r shear represents the initial length of the stacking fault shear strengthening phase, ρ SF represents the stacking fault density, represents the radius of the precipitated phase, represents the amount of precipitated phase involved in shearing, Г SF represents the stacking fault shear frequency.

[0023] Furthermore, in S22, the creep strain rate caused by stacking fault shear is The calculation formula is:

[0024] ;

[0025] Where b represents the Burgers vector of nickel-based superalloy, ΔL SF represents the stacking fault shear distance, ρSF Represents the stacking fault density.

[0026] Furthermore, in S23, the creep damage D of the creep hole c The calculation formula is:

[0027] ;

[0028] Where B represents the material constant, represents the creep strain rate, and ε represents the creep strain.

[0029] Furthermore, in S24, the creep damage D carbide The calculation formula is:

[0030] ;

[0031] Where D carbide,i represents the diameter of the i-th carbide, and i represents the number of carbide species.

[0032] Furthermore, in S25, the creep performance prediction model The expression is:

[0033] ;

[0034] In the formula, represents the creep strain rate caused by dislocation slip, D carbide represents the creep damage of carbide coarsening, D c represents the creep damage of creep holes, A represents the temperature-related coefficient, T represents the creep temperature, represents the creep strain rate caused by stacking fault shear.

[0035] The beneficial effects of the present invention are:

[0036] (1) The present invention can accurately simulate the time-dependent change of creep strain of high-temperature alloys under different temperatures and stresses. 4 The long-term creep test of 1 hour usually only takes 1 hour to complete the calculation. The creep performance prediction efficiency is four orders of magnitude higher than that of traditional experimental methods, which greatly saves the manpower and time costs required for the test.

[0037] (2) The present invention can well simulate the creep properties under different test conditions. Compared with other models that only consider dislocation slip or stacking fault and are only valid under specific test conditions, the present model can predict the creep properties of materials in a wider temperature and stress range.

[0038] (3) The present invention can predict the creep properties of nickel-based alloys with different initial microstructure parameters and different grades under different working conditions, thereby improving the versatility and universality of the prediction;

[0039] (4) The present invention can provide information on the microscopic evolution of materials during creep, provide assistance for material failure analysis, and to a certain extent provide a reference for subsequent material development and material modification;

[0040] (5) The present invention is based on the model of the initial microstructure, and can predict the creep properties of unknown materials by artificially inputting different microscopic parameters, so as to obtain the microstructure characteristics that materials with good creep properties should have. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Flow chart of the method for predicting creep mechanical properties of precipitation hardened nickel-based alloys based on microstructure. DETAILED DESCRIPTION

[0042] The embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

[0043] like Figure 1 As shown, the present invention provides a method for predicting creep mechanical properties of precipitation hardened nickel-based alloy based on microstructure, comprising the following steps:

[0044] S1. Obtain characteristic parameters of nickel-based alloy;

[0045] S2. Using the creep strain rate caused by dislocation slip and the creep strain rate caused by stacking fault shear, a creep performance prediction model is constructed;

[0046] S3. Optimizing the creep performance prediction model using characteristic parameters of nickel-based alloys;

[0047] S4. Use the optimized creep performance prediction model to complete performance prediction.

[0048] The present invention embeds the continuous damage mechanics model into the Orowan equation describing dislocation density and strain, and considers the influence of microevolution mechanisms such as recovery, precipitation coarsening, stacking fault shear and creep voids on the creep process. A creep performance prediction model based on the initial micromorphology of the material (grain size, dislocation density and stacking fault energy, etc.) is constructed to achieve high-precision prediction of the creep life of nickel-based alloys and the microevolution of the creep process. Finally, by comparing the creep data output by the model with the microstructural parameters obtained by microstructural characterization, the feasibility of the MAR-M247 high-temperature alloy creep model based on microstructure is verified.

[0049] In the embodiment of the present invention, in S1, the characteristic parameters of the nickel-based alloy include shear modulus, Poisson's ratio, Burgers vector, dislocation density, grain size, precipitate phase size and precipitate phase volume fraction.

[0050] In this embodiment of the present invention, S2 includes the following sub-steps:

[0051] S21. Calculate the creep strain rate caused by dislocation slip;

[0052] S22, determining an evolution rate equation of stacking fault density according to the initial length of the stacking fault shear strengthening phase, and calculating the creep strain rate caused by stacking fault shear using the evolution rate equation of stacking fault density;

[0053] S23. Calculate creep damage of creep holes;

[0054] S24. Calculate creep damage of carbide coarsening;

[0055] S25. A creep performance prediction model is constructed based on the creep strain rate caused by dislocation slip, the creep strain rate caused by stacking fault shear, the creep damage of creep holes, and the creep damage of carbide coarsening.

[0056] In the embodiment of the present invention, in S21, the creep strain rate caused by dislocation slip The calculation formula is:

[0057] ;

[0058] In the formula, ρ m represents movable dislocation, b represents the Burgers vector of nickel-based high-temperature alloy, v g represents the dislocation sliding velocity, and M represents the Taylor factor.

[0059] Total dislocation density ρ in nickel-based alloys t It can be expressed as the movable dislocation ρ m , boundary dislocation ρ d and dipole dislocation ρ b The sum of is calculated as: t =ρ m +ρ d +ρ b .

[0060] Mobile dislocations refer to dislocations that can slide freely within a grain under stress; boundary dislocations refer to dislocations that form subgrain boundaries; and dipole dislocations refer to dislocations that form dipole or multipolar bundles. During creep, these mobile dislocations will form dipole dislocations, which will further evolve into boundary dislocations. Therefore, the density of mobile dislocations during creep will be mainly determined by Calculate, where represents the rate at which mobile dislocations increase in number, is the mobile dislocation annihilation rate, represents the rate of conversion to boundary dislocations, which is calculated as ; In the formula, v c is the dislocation climb velocity, d spon represents the critical distance for spontaneous annihilation of dislocations, L represents the average secondary crystal diameter, and Λ represents the slip distance of mobile dislocations.

[0061] In the embodiment of the present invention, in S22, the evolution rate equation of the stacking fault density is The expression is:

[0062] ;

[0063] In the formula, r shear represents the initial length of the stacking fault shear strengthening phase, ρ SF represents the stacking fault density, represents the radius of the precipitated phase, represents the amount of precipitated phase involved in shearing, Г SF represents the stacking fault shear frequency.

[0064] In the embodiment of the present invention, in S22, the creep strain rate caused by stacking fault shear The calculation formula is:

[0065] ;

[0066] Where b represents the Burgers vector of nickel-based superalloy, ΔL SF represents the stacking fault shear distance, ρ SF Represents the stacking fault density.

[0067] The initial length r of the stacking fault shear strengthening phase shear The calculation formula is , where represents the average distance between two adjacent stacking fault shear strengthening phases, r represents the stacking fault width, γ APB represents the antiphase boundary energy, γ SFE Represents stacking fault energy.

[0068] Considering that stacking faults do not interact with all stacking fault shear strengthening phases, we introduce The term is used to represent the probability of stacking fault shearing, thereby deriving the evolution equation of stacking fault density.

[0069] In the embodiment of the present invention, in S23, the creep damage D of the creep hole c The calculation formula is:

[0070] ;

[0071] Where B represents the material constant, represents the creep strain rate, and ε represents the creep strain.

[0072] In the embodiment of the present invention, in S24, the creep damage D of carbide coarsening carbide The calculation formula is:

[0073] ;

[0074] Where D carbide,i represents the diameter of the i-th carbide, and i represents the number of carbide species.

[0075] In the embodiment of the present invention, in S25, the creep performance prediction model The expression is:

[0076] ;

[0077] In the formula, represents the creep strain rate caused by dislocation slip, D carbide represents the creep damage of carbide coarsening, D c represents the creep damage of creep holes, A represents the temperature-related coefficient, T represents the creep temperature, represents the creep strain rate caused by stacking fault shear.

[0078] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A method for predicting creep mechanical properties of precipitation-hardened nickel-based alloys based on microstructure, characterized in that: The following steps are involved: S1. Obtain characteristic parameters of nickel-based alloy; S2. Using the creep strain rate caused by dislocation slip and the creep strain rate caused by stacking fault shear, a creep performance prediction model is constructed; S3. Optimizing the creep performance prediction model using characteristic parameters of nickel-based alloys; S4. Complete performance prediction using the optimized creep performance prediction model; The S2 comprises the following sub-steps: S21. Calculate the creep strain rate caused by dislocation slip; S22, determining an evolution rate equation of stacking fault density according to the initial length of the stacking fault shear strengthening phase, and calculating the creep strain rate caused by stacking fault shear using the evolution rate equation of stacking fault density; S23. Calculate the creep damage of creep holes; S24. Calculate creep damage of carbide coarsening; S25, constructing a creep performance prediction model based on the creep strain rate caused by dislocation slip, the creep strain rate caused by stacking fault shear, the creep damage of creep holes, and the creep damage of carbide coarsening; The S25 creep performance prediction model The expression is: ； In the formula, represents the creep strain rate caused by dislocation slip, D carbide represents the creep damage of carbide coarsening, D c represents the creep damage of creep holes, A represents the temperature-related coefficient, T represents the creep temperature, represents the creep strain rate caused by stacking fault shear.

2. The method for predicting creep mechanical properties of precipitation-hardened nickel-based alloys based on microstructure according to claim 1, characterized in that: In S1, the characteristic parameters of the nickel-based alloy include shear modulus, Poisson's ratio, Burgers vector, dislocation density, grain size, precipitate phase size and precipitate phase volume fraction.

3. The method for predicting creep mechanical properties of precipitation-hardened nickel-based alloys based on microstructure according to claim 1, characterized in that: The S21 is the creep strain rate caused by dislocation slip. The calculation formula is: ； In the formula, ρ m represents movable dislocation, b represents the Burgers vector of nickel-based high-temperature alloy, v g represents the dislocation sliding velocity, and M represents the Taylor factor.

4. The method for predicting creep mechanical properties of precipitation-hardened nickel-based alloys based on microstructure according to claim 1, characterized in that: In S22, the evolution rate equation of stacking fault density is The expression is: ； In the formula, r shear represents the initial length of the stacking fault shear strengthening phase, ρ SF represents the stacking fault density, represents the radius of the precipitated phase, represents the amount of precipitated phase involved in shearing, Г SF Represents the stacking fault shear frequency.

5. The method for predicting creep mechanical properties of precipitation-hardened nickel-based alloys based on microstructure according to claim 1, characterized in that: In S22, the creep strain rate caused by stacking fault shear The calculation formula is: ； Where b represents the Burgers vector of nickel-based superalloy, ΔL SF represents the stacking fault shear distance, ρ SF Represents the stacking fault density.

6. The method for predicting creep mechanical properties of precipitation-hardened nickel-based alloys based on microstructure according to claim 1, characterized in that: In S23, the creep damage D of the creep hole c The calculation formula is: ； Where B represents the material constant, represents the creep strain rate, and ε represents the creep strain.

7. The method for predicting creep mechanical properties of precipitation-hardened nickel-based alloys based on microstructure according to claim 1, characterized in that: In the S24, the creep damage of carbide coarsening D carbide The calculation formula is: ； Where D carbide,i represents the diameter of the i-th carbide, and i represents the number of carbide species.

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