Method for calculating creep rate of oxide dispersion strengthened steel in irradiation environment

Abstract

The application relates to a method for calculating the creep rate of oxide dispersion strengthened steel in a radiation environment. The method effectively combines the theory of radiation-induced point defect evolution, the Ostwald ripening theory of oxide particle coarsening in a radiation environment, the theory of dislocation loop hardening caused by radiation, and the oxide dispersion strengthening theory of oxide particle size distribution and spatial distribution. The method considers the effects of the specific point defect evolution, oxide particle coarsening, dislocation loop hardening, and size distribution and spatial distribution of the oxide particles in a radiation environment on the performance of the oxide dispersion strengthened steel, so as to realize quantitative calculation and analysis of the creep rate of the oxide dispersion strengthened steel in a radiation environment. The threshold stress obtained by the method is in good agreement with the experimental results. The related strengthening mechanisms analyzed in the application have important significance for studying and analyzing the mechanical properties of the oxide dispersion strengthened steel at different temperatures and radiation times in a radiation environment. Through the analysis method provided by the application, the temperature of the radiation environment is changed, the value of the radiation time is regulated, the micro defect evolution and the creep rate of the oxide dispersion strengthened steel under different conditions are studied, and thus theoretical guidance is provided for the design of high-performance oxide dispersion strengthened steel.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of creep rate calculation under irradiation environment, and particularly relates to the theory of irradiation-induced point defect evolution, the Ostwald ripening theory of oxide particle coarsening under irradiation environment, the theory of dislocation loop hardening caused by irradiation, the oxide dispersion strengthening theory, and the establishment of a theoretical model considering the evolution of micro defects in the matrix and the coarsening of oxide particles under irradiation environment, so as to realize the analysis of the creep rate of oxide dispersion strengthened steel under irradiation environment. BACKGROUND

[0002] Oxide dispersion strengthened (ODS) steels are one of the most promising materials for the construction of future fourth generation nuclear fission reactors and nuclear fusion devices. Compared with traditional ferritic steels, they exhibit superior performance when subjected to a large amount of neutron irradiation and high operating temperatures. The dispersed oxide nanoparticles in the matrix can produce a high density of particle-matrix interfaces, small grain sizes, and high dislocation densities. These microstructural features can act as sinks for irradiation-induced point defects, thereby making ODS steels perform better in terms of resistance to radiation hardening and swelling. Many studies have shown that ODS steels as reactor structural materials have stability within a certain temperature and dose rate range. However, under long-term irradiation conditions, it is unlikely that the oxide particles will retain their original structure, and larger particles will significantly decrease in size after irradiation. Therefore, it is necessary to have a deep understanding of the microstructural evolution and the degree to which point defects produced during irradiation act as sinks, thereby affecting the creep rate of the material.

[0003] The study of the effects of changes induced by neutron irradiation on microstructure and mechanical properties is a key to the successful application of ODS steels to advanced fission and fusion reactor components. Current studies have verified the structure and properties of ODS steels under irradiation conditions by neutron irradiation. The nanoindentation deformation behavior of heavy ion irradiation was studied, and the results showed that the irradiated material exhibited a lower strain rate during the loading stage, while the strain rate of the irradiated material was higher than that of the unirradiated material after reaching the maximum load. The microstructure evolution was studied from low to high doses, and only a small amount of dislocation loops was observed at low doses, and cavities were preferentially formed at the oxide / matrix interface. As the dose increased, the dislocation loops evolved into dislocation networks, and the cavities gradually accumulated at the grain boundaries and dislocation lines. The effect of fast neutron irradiation on the tensile properties of ODS steel cladding rings for fast reactors was studied, and the results showed that the tensile strength did not change significantly at irradiation temperatures below 923 K, while at neutron irradiation temperatures above 1023 K, the tensile strength decreased by up to 20% to 33 dpa. There are many other studies on irradiation, such as the effect of irradiation dose and dose rate on the evolution of dislocation loops and cavities in Fe-9%Cr oxide dispersion strengthened steel and commercial ferritic-martensitic steels HCM12A and HT9. The mechanical response of the second-generation ODS Eurofer97 steel after neutron irradiation at 300°C was studied. The irradiation creep and microstructure changes of two ferritic ODS steels containing 12% and 14% Cr under uniaxial tensile stress from 40 to 300 MPa were investigated. The effects of material composition, ODS particle size, and bombarding particles on irradiation creep flexibility were studied.

[0004] Most of the research projects so far have relied on experimental verification results, and theoretical research is relatively less, so understanding the mechanism of defect formation is very important for understanding the effect of ODS particles on radiation resistance and the relationship between irradiation-altered microstructure and mechanical properties. Defect clusters can have a detrimental effect on structural materials. Irradiation can lead to the formation of nanoscale dislocation loops, cavities, and other defects, ultimately leading to an increase in material hardness and a brittle temperature transition. As a result, the material becomes fragile and the toughness decreases. In this study, we calculated the evolution of point defects under irradiation by the rate equation and studied the coarsening of the oxide particles. The effect of sink on irradiation damage was studied, the effect of dislocation loops on the creep resistance of the material was studied, and the relationship between the activation energy and the creep lifetime at different temperatures was studied. SUMMARY

[0005] The purpose of the present application is to propose a quantitative calculation and analysis method of the creep rate of oxide dispersion strengthened steel based on experimental data combined with consideration of the theory of irradiation-induced point defect evolution, the Ostwald ripening theory of oxide particle coarsening under irradiation environment, the dislocation loop hardening theory caused by irradiation, and the oxide dispersion strengthening theory.

[0006] The technical solution of the present application is:

[0007] The material parameters of the used ODS steel are determined, including the related parameters of the physical parameters of elements. The material used in the present application is Fe-13Cr-2W-0.4Ti-0.6Zr (wt%), and the material parameters are as shown in Table 1:

[0008] Table 1: Physical parameters of each element.

[0009]

[0010] The generation and evolution of point defects (self-interstitial atoms, vacancies) and dislocation loops caused by ion irradiation are analyzed using the rate model. The growth and shrinkage of dislocation loops depend on the balance of point defects entering and flowing out of the dislocation loop, which corresponds to the absorption and emission of point defects. We assume that point defects are generated at a constant rate and are mobile before recombination with another point defect. The rate of change of the concentration of self-interstitial atoms and vacancies is described as follows:

[0011]

[0012] where C V is the concentration of interstitial atoms, C I is the vacancy concentration. G0 is the irradiation flux, which is used to describe the generation of point defects caused by radiation. D V and D I are the diffusion coefficients of vacancies and interstitial atoms, respectively. R is the recombination term, which can be expressed as:

[0013]

[0014] where d rec is the Frenkel pair radius. V at is the atomic volume. The absorption body intensity depends on the geometry and spatial distribution of the absorber. For a spherical geometry of the absorber, the absorption body intensity is given by the following formula:

[0015] k s = 4πR s Cs (3)

[0016] where Rs is the capture radius and Cs is the concentration at the sink. The number density and radius of dislocation loops during irradiation are described as follows:

[0017]

[0018] C L is the number density, r L is the radius of the dislocation loop. Z I and Z V are the capture efficiencies.

[0019] We explained the phenomenon that the coarsening of large nano-oxide particles during irradiation is at the expense of the dissolution of small nano-oxide particles using the Oswald ripening. The average size of the nano-oxide particles can be expressed as:

[0020]

[0021] where r is the average radius of the nano-oxide particles, r0 is the initial radius of the nano-oxide particles, γ is the surface free energy of the ODS interface, D is the diffusion coefficient, C ∞ is the limiting solubility of the ODS interface, V m is the molar volume, t is time, R is the universal gas constant, and T is temperature. Here, an approximation method was used in the derivation of the formula, i.e., C P -C r ≈ C P -C ∞ , where C r is the solubility at the interface of the oxide particles with a radius of curvature r.

[0022] Considering that the irradiation dose is proportional to the irradiation time, the average size of the oxide particles is expressed as:

[0023]

[0024] where k d is a constant proportional to the diffusion coefficient. The constant k d was fitted as a function of temperature k d = 0.031T-23.612. φ is the total irradiation dose obtained by the product of the irradiation rate and time, expressed as φ = G0t.

[0025] We used the FKH model to calculate the hardening of dislocation loops caused by irradiation. This model provides a mechanism to explain the phenomenon of material hardening caused by irradiation by considering the hindering effect of defects on dislocation motion. Its expression is:

[0026]

[0027] Where M is the Taylor factor, G is the shear modulus, and b is the Burgers vector of the dislocation. d and N are the defect size and defect number density, respectively.

[0028] Oxide diffusion strengthening is controlled by two mechanisms, the cross-strengthening mechanism τ cutting 、Orowan bypasses the reinforcement mechanism τ orowan and the climbing mechanism τ climb The critical shear stress model of oxide particles can be expressed as:

[0029]

[0030] τ=min(τ climb ,τ orowan ,τ cutting ) (9)

[0031] Among them, A and B are constant parameters, D is the diameter of the particle in space, L is the distance between particles, r a is the dislocation core radius, assumed to be the magnitude of the Burgers vector. ε is the misfit strain, calculated as ε = b / 4r, where r is the radius of the oxide particle, which can be obtained experimentally. τ represents the minimum stress for the three interaction mechanisms.

[0032] As attached Figure 1 Given τ cutting and τ Orowan As shown in the curve, there is a critical size r for the transition of the interaction mechanism between dislocations and oxide particles. Critical When r≤r Critical When r>r Critical When the oxide diffusion strengthening is Orowan bypass strengthening mechanism. Figure 2 (a) and (b) show that the dislocation is r≤r Critical When the oxide particles are cut, the cutting strengthening mechanism is triggered; when the dislocation is r>r Critical When the oxide particles are cut, the Orowan bypass strengthening mechanism is triggered, which well explains the spatial distribution of the oxide particles. Figure 2 As shown in (a), region AB triggers the shear strengthening mechanism, and region OA triggers the Orowan bypass strengthening mechanism. The triggering probability of different oxide diffusion strengthening mechanisms can be calculated by the ratio of the distance from the center of the interaction surface A to point B to the radius r of the spherical oxide particle. It can be seen that for the shear strengthening mechanism region, the triggering probability is:

[0033]

[0034] For the Orowan bypassing strengthening mechanism, the triggering probability is:

[0035] p1(r) = 1 - p2(r) (11)

[0036] For the climb strengthening mechanism, the triggering probability p0 is obtained by comparing the applied shear stress and the critical shear stress (CRSS).

[0037] The recalculation of the oxide dispersion strengthening mechanism considering the spatial distribution by the differential quadrature method can be expressed as:

[0038]

[0039] where τ climb (r), τ cutting (r) and τ orowan (r) represent the critical disintegration shear stress of the climb mechanism, the cutting mechanism and the Orowan mechanism.

[0040] And the size distribution is to consider that the average size of the individual oxide particles distributed in the matrix is different, and the average size values present a normal distribution law, and the probability formula is:

[0041]

[0042] where μ and σ are the geometric mean and geometric standard deviation of ln(r).

[0043] Based on the above, the coupling processing of the above strengthening mechanism formula (irradiation-induced point defect strengthening, oxide particle coarsening mechanism in irradiation environment, dislocation loop hardening mechanism caused by irradiation, oxide dispersion strengthening mechanism considering spatial distribution and size distribution) can obtain a new threshold stress model of oxide dispersion strengthened steel in irradiation environment:

[0044]

[0045] where r m is the maximum size of the particle, r c is the critical size of the particle, and f(r) is the normal distribution function.

[0046] The coupled threshold stress can be regarded as the coupling creep resistance of defects, dislocation loops and oxide particles in the irradiation environment. The creep rate unified equation considering the irradiation-induced point defect evolution theory, the Ostwald ripening theory of oxide particle coarsening in irradiation environment, the dislocation loop hardening theory caused by irradiation, and the oxide dispersion strengthening theory is:

[0047]

[0048] τ L is the dislocation line tension, τL = 0.5 Gb 2 .c L is the strain hardening parameter, c L = 10. Alpha is the Taylor constant depending on the lattice structure, alpha = 0.33. N is the dislocation mobility, which depends on the applied stress, threshold stress and temperature. The dislocation mobility is described by the following equation:

[0049]

[0050] D 0sd is the pre-exponential factor, k B is the Boltzmann constant, Q sd is the self-diffusion activation energy, R g is the gas constant, R m is the tensile strength.

[0051] Finally, the calculation results are processed and data analyzed to obtain the comparison of the model with experimental data and the trend of the creep rate and the creep strain changing with the irradiation applied time at different temperatures.

[0052] Advantages

[0053] The present application proposes a method for calculating the creep rate of oxide dispersion strengthened steel in an irradiation environment, which considers the irradiation-induced point defect evolution theory, the Ostwald ripening theory of oxide particles in the irradiation environment, the dislocation loop hardening theory caused by irradiation, and the oxide dispersion strengthening theory of the size distribution and spatial distribution of oxide particles to realize the analysis of the creep rate of oxide dispersion strengthened steel with time in the irradiation environment. The method is based on a solid theoretical foundation, a clear modeling process and clear physical meaning.

[0054] The present application takes Fe-13Cr-2W-0.4Ti-0.6Zr (wt%) oxide dispersion strengthened steel as an example, selects Y2O3 as the added oxide particles, uses the related data measured by experiments, realizes the calculation of the qualitative and quantitative relationship of the alloy creep rate through the strength theoretical model in the calculation method, and the result is in good agreement with the experiment, so that the evolution curve of the creep rate and the creep strain changing with the irradiation applied time at different temperatures is obtained, which provides theoretical guidance for analyzing the defect evolution and anti-creep property of oxide dispersion strengthened steel in the irradiation environment. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 is the corresponding oxide dispersion strengthening mechanism under different oxide particle radii.

[0056] Figure 2 is a schematic diagram of dislocation bypassing oxide particles. (a) spherical oxide particles; (b) dislocation shearing or bypassing oxide particles.

[0057] Figure 3 is the comparison of experimental data with the current model.

[0058] Figure 4 is (a) the change of creep strain with irradiation time of oxide dispersion strengthened steel at different temperatures under irradiation environment; (b) the change of creep rate with irradiation time of oxide dispersion strengthened steel at different temperatures under irradiation environment; (c) the change of radius of oxide particles with irradiation time at different temperatures under irradiation environment; (d) the change of radius of dislocation loop in the matrix of oxide dispersion strengthened steel with irradiation time at different temperatures under irradiation environment. DETAILED DESCRIPTION

[0059] The following description will be given in conjunction with the accompanying drawings Figure 1 The oxide dispersion strengthening mechanisms corresponding to different oxide particle radii are given in the accompanying drawings, and the schematic diagram of the interaction between dislocations and oxide particles is given. Figure 2 The oxide dispersion strengthening steel creep rate model under irradiation considers the theoretical model and specific examples of four effects, i.e., the interaction mechanism between dislocations and oxide particles, the irradiation-induced point defect evolution theory, the Ostwald ripening theory of oxide particle coarsening under irradiation environment, and the dislocation loop hardening theory caused by irradiation. The technical scheme is further described, and the present application is not limited to the following examples. Any design idea using the present application falls within the protection scope of the present application.

[0060] Oxide dispersion strengthening refers to adding a certain amount of thermodynamically stable oxides in high-temperature alloys, so that the oxides are dispersedly distributed in the matrix to form an oxide dispersion phase insoluble in the matrix. The new phase hinders the movement of dislocations, thereby strengthening the mechanical properties of the material. Irradiation-induced point defect evolution is a phenomenon that atoms in the metal matrix obtain energy higher than the displacement threshold energy and deviate from the original lattice point position during irradiation. These point defects migrate, aggregate, recombine, and annihilate at a certain temperature, thereby forming various mesoscale defect clusters and affecting the microstructure of the material and further affecting its macroscopic properties. During irradiation, the oxide particles will coarsen, and the Ostwald ripening theory explains that the coarsening of large nanometer oxide particles during irradiation is at the expense of the dissolution of small nanometer oxide particles. The dislocation loops in the matrix under irradiation environment will significantly hinder the movement of dislocations, thereby severely hindering the movement of dislocations and causing the hardness and yield strength of the material to increase.

[0061] Specific steps: collect the experimental data of Fe-13Cr-2W-0.4Ti-0.6Zr (wt%) with added oxide particles Y2O3 to obtain the material parameters involved in the method, as shown in Table 2.

[0062] Table 2: Various material parameters

[0063]

[0064]

[0065] By fitting the relevant experimental data of oxide dispersion strengthened steel in irradiation environment, the threshold stress experimental results, comparison of the current model are obtained Figure 3 It can be seen from the attached Figure 3 After considering the various coupling strengthening theories mentioned in this paper, the calculation accuracy of the current model is higher.

[0066] The attached Figure 4 (a, b) is to predict the change of creep strain and creep rate with irradiation time under the condition of applying stress σ APP =100MPa at different temperature environments. The attached Figure 4 (a) can be seen that temperature has a considerable influence on the creep strain of oxide dispersion strengthened steel in irradiation environment, the lowest creep strain is 1.2% at 500℃, while the creep strain is as high as 3.1% at 800℃, the creep strain increases by about two times. With the increase of environmental temperature, the creep strain increases. In the attached Figure 4 (b), the creep strain and creep rate show the same trend, both gradually increase with the increase of irradiation time. At different irradiation times, the response trend of creep strain and creep rate to temperature change is the same, but the change rate is different with the increase of irradiation time. However, at the same temperature, the change of creep rate and creep strain with irradiation time is small.

[0067] The attached Figure 4 (c, d) shows the evolution of oxide particle radius and dislocation loop radius with irradiation time at different temperatures. The attached Figure 4 (a) shows that for oxide particles, the radius increases linearly with time. Its coarsening rate is a function of temperature; the higher the temperature, the greater the coarsening rate. The attached Figure 4 (d) shows that the radius of dislocation loop increases rapidly before 200 hours of irradiation time, and reaches a maximum of 8.4nm at about 400 hours.

[0068] Therefore, the present application has good analysis accuracy of creep rate of oxide dispersion strengthened steel in irradiation environment, and can effectively predict the influence of irradiation time on alloy creep rate under different temperatures and applied stress, providing a reliable theoretical model for analyzing the micro defect evolution and creep resistance of oxide dispersion strengthened steel in irradiation environment.

Claims

1. A method for calculating the creep rate of oxide-dispersion-strengthened steel under irradiation, combining the theory of radiation-induced point defect evolution, the Ostwald ripening theory of oxide particle coarsening under irradiation, the theory of radiation-induced dislocation loop hardening, and the oxide dispersion strengthening theory of oxide particle size and spatial distribution with a creep rate model. The method is characterized by: The strengthening effects of oxide particles, defect evolution, and dislocation loops in oxide-dispersion-strengthened steel under irradiation were considered. Defect evolution and dislocation loops in the material are generated when the matrix is ​​in the irradiation environment, while oxide particles are added during processing. By considering the strengthening model of oxide-dispersion-strengthened steel under irradiation that couples multiple influencing mechanisms, quantitative analysis of the creep rate of oxide-dispersion-strengthened steel under irradiation is achieved. While the application time and irradiation dose rate of the irradiation environment can be controlled, the creep rate and threshold stress of oxide-dispersion-strengthened steel under irradiation conditions are obtained, providing guidance for the design of oxide-dispersion-strengthened steels with better performance. The method specifically involves the following steps: determining the basic material parameters required in the model and collecting relevant physical parameters of the relevant materials; calculating the strength values ​​contributed by the various strengthening mechanisms, including oxide dispersion strengthening theory, radiation-induced point defect evolution theory, Ostwald ripening theory of oxide particle coarsening under irradiation, and radiation-induced dislocation loop hardening theory; and coupling the above strengthening mechanisms to obtain the threshold stress of oxide dispersion-strengthened steel under irradiation: in, σ thr (r) is the threshold stress, M is the Taylor constant, r m is the maximum oxide particle size, r c is the critical size of the oxide particles, τ climb is the climbing mechanism, τ cutting is the cutting strengthening mechanism, τ orowan is the Orowan bypass reinforcement mechanism, f(r) is the normal distribution function, Δσ y It is dislocation loop hardening; The coupled threshold stress can be regarded as the coupled creep resistance of defects, dislocation loops, and oxide particles in the irradiation environment. Considering the theory of irradiation-induced point defect evolution, the Ostwald ripening theory of oxide particle coarsening in the irradiation environment, the theory of irradiation-induced dislocation loop hardening, and the theory of oxide dispersion strengthening, the creep rate of oxide dispersion strengthened steel is expressed as: Among them, τ L is the dislocation line tension, τ L =0.5Gb 2 ; G is the shear modulus, b is the Burgers vector, N is the dislocation mobility, c L is the strain hardening parameter, c L =10; α depends on the lattice constant, α = 0.33; the dislocation mobility is described by the following formula: Among them, D osd is the pre-exponential factor, k B is the Boltzmann constant, T is the temperature, Q sd is the self-diffusion activation energy, R g is the gas constant, R m is the tensile strength; Oxide particles also have a strengthening effect on the mechanical properties of materials by hindering dislocation movement. The main mechanism of oxide particle strengthening is the cutting strengthening mechanism τ cutting 、Orowan bypasses the reinforcement mechanism τ orowan and the climbing mechanism τ climb ; Their expressions are: τ=min(τ climb ,t orowan ,t cutting ) Where A and B are constants, L is the interparticle distance, D is the diameter of the particle in space, and r a is the dislocation core radius, assumed to be the magnitude of the Burgers vector; ε is the misfit strain, ε = b / 4r; τ represents the minimum stress for the three interaction mechanisms; There is a critical size r for the transition of the interaction mechanism between dislocations and oxide particles. c ; when r≤r c When r>r c When the oxide diffusion strengthening is the Orowan bypass strengthening mechanism, and the dislocation is r≤r c When the oxide particles are cut, the cutting strengthening mechanism is triggered; when the dislocation is r>r c When the oxide particles are cut, the Orowan bypass strengthening mechanism is triggered; the formula considering the spatial distribution of each oxide diffusion strengthening component can be written as: For the area that cuts through the strengthening mechanism, the probability of triggering p2 is: For Orowan bypassing the reinforcement mechanism, the probability of triggering p1 is: p1(r)=1-p2(r) For the climb strengthening mechanism, the probability of triggering p0 is obtained by comparing the applied stress with the critical shear stress; In the oxide dispersion strengthened Fe-13Cr-2W-0.4Ti-0.6Zr steel, the contents of each component are expressed in mass percentages, and the sizes of the oxide particles are normally distributed: When r≤r c When r>r c When , the oxide dispersion strengthening is the Orowan bypass strengthening mechanism; through calculus, the oxide particle size distribution radius area is divided into n parts, and the oxide dispersion strengthening formula of size distribution can be expressed as: To calculate the defect evolution in an irradiated environment, it is assumed that point defects are generated at a constant rate and are mobile before recombination with another point defect; the concentration change rate of self-interstitial atoms and vacancies is described as follows: Among them, C V is the interstitial atom concentration, C I is the vacancy concentration, D V is the vacancy diffusion coefficient, D I is the interstitial atomic diffusion coefficient; G0 is the irradiation flux, which is used to describe the generation of point defects caused by radiation; R is a composite term, which can be expressed as: Among them, d rec is the Frenkel pair radius, V at is the atomic volume; the absorber strength depends on the absorber geometry and spatial distribution; for a spherical absorber, the absorber strength is given by the following formula: k s =4πR s C s Among them, R s is the capture radius, C s is the concentration at the convergence point; the number density and radius of the dislocation loop during irradiation are described as follows: Among them, C L is the number density of dislocation loops, r L is the radius of the dislocation loop, Z I and Z V is the capture efficiency; The coarsening of oxide particles in the irradiation environment is calculated, and the characteristic is that the Oswald ripening is used to explain the phenomenon that the coarsening of large nano-oxide particles during irradiation is at the expense of the dissolution of small nano-oxide particles; the size of the nano-oxide particles can be expressed as: where r0 is the initial radius of the nano-sized oxide particle, γ is the surface free energy of the oxide particle interface, D is the diffusion coefficient, and C P is the solubility at the oxide particle interface, C ∞ is the limiting solubility at the oxide particle interface, V m is the molar volume, t is the time, R o is the universal gas constant, T is the temperature; an approximation is used in the derivation of the formula, namely C P -C r ≈C P -C ∞ , here C r is the solubility at the interface of oxide particles with a curvature radius of r; Considering that the irradiation dose is proportional to the irradiation time, the average size of the oxide particles is expressed as follows: Among them, k d is a constant proportional to the diffusion coefficient and is fitted as a function of temperature k d =0.031T-23.612; φ is the total radiation dose obtained by multiplying the irradiation rate and time, expressed as φ=G0t; Calculate the hardening value of dislocation loops in an irradiated environment; use the FKH model to calculate the radiation-induced dislocation loop hardening. This model provides a mechanism to explain the radiation-induced material hardening phenomenon by considering the obstruction of dislocation motion by defects. Its expression is: Among them, D d and W are the defect size and defect number density, respectively.

2. The method for calculating creep rate of oxide dispersion strengthened steel under irradiation environment according to claim 1, characterized in that The inherent parameters of the elements in the material and the existing experimental data are used to accurately calculate the creep rate and threshold stress changes with irradiation at different temperatures for the defect evolution and strength and creep rate models involved.

3. The method for calculating creep rate of oxide dispersion strengthened steel under irradiation environment according to claim 1, characterized in that: Determine the effective material parameters; the material used is Fe-13Cr-2W-0.4Ti-0.6Zr steel with oxide particles as Y2O3, in which the mass fractions of the elements Cr, W, Ti, Zr, Si, Y2O3, and Fe are 13%, 2%, 0.4%, 0.6%, 0.3%, 0.24%, and 83.46%, respectively.

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