Method for determining specific precipitation time and morphology of t3 phase, t6 phase and t7 phase in reactor pressure vessel steel

Abstract

Embodiments of the present application relate to the technical field of computer materials science, in particular to a method for determining specific precipitation time and morphology of t3 phase, t6 phase and t7 phase in reactor pressure vessel steel, comprising: determining chemical free energy, gradient free energy and elastic free energy of t3 phase, t6 phase and t7 phase in reactor pressure vessel steel, and determining total free energy of a five-element four-phase system composed of Fe, Cu, Mn, Ni, Si five-element alloy, t3 phase, t6 phase, t7 phase and matrix phase, with the addition of interface interaction of t3 phase, t6 phase, t7 phase and matrix phase; determining interface mobility of t3 phase, t6 phase and t7 phase in matrix phase; determining element distribution in reactor pressure vessel steel according to the total free energy; and determining specific precipitation time and morphology of t3 phase, t6 phase and t7 phase according to the total free energy, interface mobility and distribution. The method is conducive to realizing high-precision prediction of specific precipitation time and morphology of t3 phase, t6 phase and t7 phase precipitated after long-term service of reactor pressure vessel steel.

Description

Technical Field

[0001] The embodiments of this application relate to the field of computer materials science and technology, specifically to a method for determining the specific precipitation time and morphology of the t3, t6, and t7 phases in reactor pressure vessel steel. Background Technology

[0002] The statements herein are provided merely as background information in connection with this application and do not necessarily constitute prior art.

[0003] The reactor pressure vessel (RPV) is a critical, irreplaceable component in a nuclear power plant. Its main material is RPV steel, which is primarily composed of a five-element alloy of Fe, Cu, Mn, Ni, and Si. Due to the long-term operation of the reactor pressure vessel under neutron irradiation and high-temperature, high-pressure environments, Cu, Mn, Ni, and Si elements in the reactor pressure vessel steel will segregate. In high-copper alloys, Cu segregation is dominant, resulting in the precipitation of a copper-rich phase. In low-copper alloys, Mn, Ni, and Si segregation is dominant, and t3, t6, and t7 phases will precipitate in the matrix phase. This leads to irradiation embrittlement of the alloy, significantly reducing impact toughness and fracture toughness, and exacerbating the deterioration of material properties.

[0004] Therefore, there is an urgent need for a method that can accurately predict the formation process of the t3, t6, and t7 phases in reactor pressure vessel steel, so as to predict the mechanical properties of reactor pressure vessel steel, thereby accurately assessing the irradiation life of nuclear reactor pressure vessels and ensuring the safe operation of nuclear power plants. Summary of the Invention

[0005] A brief overview of this application is provided below to offer a basic understanding of certain aspects thereof. It should be understood that this overview is not an exhaustive summary of the application. It is not intended to identify key or essential parts of the application, nor is it intended to limit its scope. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0006] This application provides a method for determining the specific precipitation time and morphology of the t3, t6, and t7 phases in reactor pressure vessel steel. The reactor pressure vessel steel is composed of a five-element alloy of Fe, Cu, Mn, Ni, and Si. The method includes the following steps: S10: Determining the chemical free energy, gradient free energy, and elastic free energy caused by the precipitation of the t3, t6, and t7 phases in the reactor pressure vessel steel; S20: Based on the chemical free energy, gradient free energy, and elastic free energy of the t3, t6, and t7 phases determined in step S10, determining the precipitation time and morphology of the five-element alloy of Fe, Cu, Mn, Ni, and Si, the t3, t6, and t7 phases, and the matrix phase. The total free energy of the five-element four-phase system involving the interaction of the t3, t6, t7 phases and the matrix phase interfaces was determined in step S20; S30: the interfacial migration rates of the t3, t6, and t7 phases in the matrix phase of the reactor pressure vessel steel were determined; S40: based on the total free energy of the five-element four-phase system determined in step S20, the distribution of Fe, Cu, Mn, Ni, and Si in the reactor pressure vessel steel was determined; S50: based on the total free energy of the five-element four-phase system determined in step S20, the interfacial migration rates of the t3, t6, and t7 phases in the matrix phase of the reactor pressure vessel steel determined in step S30, and the distribution of Fe, Cu, Mn, Ni, and Si in the reactor pressure vessel steel determined in step S40, the specific precipitation time and morphology of the t3, t6, and t7 phases in the reactor pressure vessel steel were determined.

[0007] The method provided in this application for determining the specific precipitation time and morphology of the t3, t6, and t7 phases in reactor pressure vessel steel is based on the chemical free energy, gradient free energy, and elastic free energy data caused by precipitation of the t3, t6, and t7 phases in reactor pressure vessel steel. It introduces the total free energy of a five-element four-phase system composed of a five-element alloy of Fe, Cu, Mn, Ni, and Si, the t3, t6, t7 phases, and the matrix phase, incorporating the interfacial interactions between the t3, t6, t7 phases, and the matrix phase. This integrates the influence of the gradient energy of interfacial interactions between different phases on the evolution of the multiphase interface, reflecting the contribution of different elements and phases to the energy of the five-element four-phase system, thus achieving a complete description. The thermodynamic properties of the five-element, four-phase system facilitate the accurate determination of the distribution of Fe, Cu, Mn, Ni, and Si in reactor pressure vessel steel based on free energy, ensuring consistency with actual conditions. Furthermore, by combining the thermodynamic and kinetic parameters of the five-element, four-phase system—namely, the total free energy and the interfacial migration rates of the t3, t6, and t7 phases within the matrix phase—it is possible to achieve high-precision prediction of the specific precipitation time and morphology of the t3, t6, and t7 phases precipitated in reactor pressure vessel steel after prolonged service. This provides reliable technical support for accurately predicting the mechanical properties of reactor pressure vessel steel and assessing the irradiation life of nuclear reactor pressure vessels. Attached Figure Description

[0008] Other objects and advantages of this application will become apparent from the following description of embodiments of this application with reference to the accompanying drawings, and will help to provide a comprehensive understanding of this application.

[0009] Figure 1 This is a distribution diagram of Cu in reactor pressure vessel steel under irradiation conditions at different times according to an embodiment of this application; Figure 2 This is a distribution diagram of Mn in reactor pressure vessel steel under irradiation conditions at different times according to an embodiment of this application; Figure 3 This is a distribution diagram of Ni in reactor pressure vessel steel under irradiation conditions at different times according to an embodiment of this application; Figure 4 This is a distribution diagram of Si in reactor pressure vessel steel under irradiation conditions at different times according to an embodiment of this application; Figure 5 This is a morphology diagram of the t3 phase precipitation in reactor pressure vessel steel under low Mn content conditions according to an embodiment of this application. Figure 6 This is a morphology diagram of the t6 phase precipitation in reactor pressure vessel steel under low Mn content conditions according to an embodiment of this application. Figure 7These are morphological images of the t3 and t6 phases of reactor pressure vessel steel under high Mn content conditions according to embodiments of this application. Figure 8 This is a particle size distribution diagram of the t3 phase in reactor pressure vessel steel with high Mn content according to an embodiment of this application. Figure 9 This is a particle size distribution diagram of the t6 phase in reactor pressure vessel steel with high Mn content, according to an embodiment of this application.

[0010] It should be noted that the accompanying drawings are not necessarily drawn to scale, but are shown only in a schematic manner without affecting the reader's understanding. Detailed Implementation

[0011] Exemplary embodiments of this application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the development of any such actual embodiment to achieve the developer's specific goals, such as complying with constraints related to the system and business, and these constraints may vary depending on the implementation. Furthermore, it should be understood that while development work can be very complex and time-consuming, such development work is merely a routine task for those skilled in the art who benefit from the content of this application.

[0012] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the equipment structure and / or processing steps closely related to the solution according to this application are shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0013] The inventors of this application have discovered that, in simulating the elemental segregation and multiphase precipitation process of reactor pressure vessel steel, the phase field simulation methods commonly used in the prior art can generally only simulate the simple coexistence of two phases precipitated in reactor pressure vessel steel, ignoring the influence of the interaction between the interfaces of the multiphases on the multiphase precipitation evolution, resulting in low simulation accuracy for the precipitation evolution of the t3 phase, t6 phase, and t7 phase.

[0014] Based on this, embodiments of this application provide a method for determining the specific precipitation time and morphology of the t3, t6, and t7 phases in reactor pressure vessel steel. The reactor pressure vessel steel is composed of a pentagonal alloy of Fe, Cu, Mn, Ni, and Si, and the method includes the following steps: S10: Determine the chemical free energy of the t3, t6, and t7 phases in reactor pressure vessel steel, the gradient free energy of the t3, t6, and t7 phases in reactor pressure vessel steel, and the elastic free energy caused by the precipitation of the t3, t6, and t7 phases in reactor pressure vessel steel.

[0015] S20: Based on the chemical free energy, gradient free energy, and elastic free energy of the t3, t6, and t7 phases in the reactor pressure vessel steel determined in step S10, determine the total free energy of the five-element four-phase system consisting of the five-element alloy of Fe, Cu, Mn, Ni, and Si, the t3 phase, the t6 phase, the t7 phase, and the matrix phase, which incorporates the interfacial interactions of the t3, t6, t7 phases and the matrix phase.

[0016] S30: Determine the interfacial migration rates of the t3, t6, and t7 phases in the matrix phase of reactor pressure vessel steel.

[0017] S40: Based on the total free energy of the five-element four-phase system determined in step S20, determine the distribution of Fe, Cu, Mn, Ni, and Si in the reactor pressure vessel steel.

[0018] S50: Based on the total free energy of the five-element four-phase system determined in step S20, the interfacial migration rates of the t3, t6, and t7 phases in the matrix phase of the reactor pressure vessel steel determined in step S30, and the distribution of Fe, Cu, Mn, Ni, and Si in the reactor pressure vessel steel determined in step S40, determine the specific precipitation time and morphology of the t3, t6, and t7 phases in the reactor pressure vessel steel.

[0019] The method provided in this application for determining the specific precipitation time and morphology of the t3, t6, and t7 phases in reactor pressure vessel steel is based on the chemical free energy, gradient free energy, and elastic free energy data caused by precipitation of the t3, t6, and t7 phases in reactor pressure vessel steel. It introduces the chemical free energy of a five-element four-phase system composed of a five-element alloy of Fe, Cu, Mn, Ni, and Si, the t3, t6, t7 phases, and the matrix phase, incorporating the interfacial interactions between the t3, t6, t7 phases, and the matrix phase. This integrates the influence of the gradient energy of interfacial interactions between different phases on the evolution of the multiphase interface, reflecting the contribution of different elements and phases to the energy of the five-element four-phase system, thus achieving a complete description. The thermodynamic properties of the five-element, four-phase system facilitate the accurate determination of the distribution of Fe, Cu, Mn, Ni, and Si in reactor pressure vessel steel based on the total free energy, ensuring consistency with actual conditions. Furthermore, by combining the thermodynamic and kinetic parameters of the five-element, four-phase system—namely, the total free energy and the interfacial migration rates of the t3, t6, and t7 phases within the matrix phase—it becomes possible to achieve highly accurate predictions of the specific precipitation times and morphologies of the t3, t6, and t7 phases that precipitate in reactor pressure vessel steel after prolonged service. This provides reliable technical support for accurately predicting the mechanical properties of reactor pressure vessel steel and assessing the irradiation life of nuclear reactor pressure vessels.

[0020] In some embodiments, determining the gradient free energies of the t3, t6, and t7 phases in the reactor pressure vessel steel in step S10 may further include the following steps: S11: Determine the gradient free energy coefficients of the matrix phase and t3 phase, the matrix phase and t6 phase, the matrix phase and t7 phase, the t3 phase and t6 phase, the t3 phase and t7 phase, and the t6 phase and t7 phase in the reactor pressure vessel steel.

[0021] S12: Based on the gradient free energy coefficients between the matrix phase and the t3 phase, the matrix phase and the t6 phase, the matrix phase and the t7 phase, the t3 phase and the t6 phase, the t3 phase and the t7 phase, and the t6 phase and the t7 phase, determined in step S11, determine the gradient free energy of the t3 phase, t6 phase, and t7 phase in the reactor pressure vessel steel.

[0022] This embodiment considers the pairwise gradient coefficients among the t3, t6, t7, and matrix phases in reactor pressure vessel steel, namely the gradient free energy coefficients between the matrix phase and the t3, t6, and t7 phases, the gradient free energy coefficients between the t3 phase and the t6, t7 phases, and the gradient free energy coefficients between the t6 phase and the t7 phase. By integrating the interaction gradient energies between the interfaces of the two phases in the t3, t6, t7, and matrix phases, the prediction accuracy of the element concentration gradient at the interface is improved. This improves the degree of conformity between the determined gradient free energies of the t3, t6, and t7 phases in the reactor pressure vessel steel and the actual situation. Consequently, it facilitates a complete description of the thermodynamic properties of the five-element four-phase system, accurately determines the total free energy of the five-element four-phase system composed of Fe, Cu, Mn, Ni, Si alloy, t3, t6, t7, and matrix phases, including the interaction of the interfaces of the t3, t6, t7, and matrix phases, and effectively enhances the authenticity and accuracy of the prediction.

[0023] In some embodiments, in step S12, the gradient free energy coefficients of the matrix phase and t3 phase, the matrix phase and t6 phase, the matrix phase and t7 phase, the t3 phase and t6 phase, the t3 phase and t7 phase, the t6 phase and t7 phase, and the gradient free energy of the t3, t6, and t7 phases in the reactor pressure vessel steel conform to the following relationship: .

[0024] in, This represents the gradient free energy of the t3, t6, and t7 phases in the reactor pressure vessel steel. The gradient free energy coefficients between the matrix phase and the t3 phase are given. The gradient free energy coefficients between the matrix phase and the t6 phase are given. The gradient free energy coefficients between the matrix phase and the t7 phase are given. The gradient free energy coefficients for phases t3 and t6 are given. The gradient free energy coefficients for phases t3 and t7 are given. The gradient free energy coefficients for phases t6 and t7 are given. For the order parameter of the matrix phase, For the sequence parameter of phase t3, For the sequence parameter of phase t6, For the t7 phase sequence parameter.

[0025] In this embodiment, the gradient free energy coefficients of the matrix phase and the t3, t6, and t7 phases, the gradient free energy coefficients of the t3 phase and the t6, t7 phases, and the gradient free energy coefficients of the t6 phase and the t7 phases are established. By specifically considering the interaction between the interfaces of different phases, the gradient energy of the interface interaction between different phases is integrated, thereby accurately determining the gradient free energy of the t3, t6, and t7 phases in the reactor pressure vessel steel.

[0026] Specifically, in the aforementioned relation, This represents the gradient free energy generated by the interfacial interactions between the matrix phase and phases t3, t6, and t7. This represents the gradient free energy generated by the interfacial interactions between phases t3, t6, and t7. This represents the gradient free energy generated between phases t6 and t7 due to interfacial interaction.

[0027] In some embodiments, determining the chemical free energies of the t3, t6, and t7 phases in the reactor pressure vessel steel in step S10 may further include the following steps: S13: Determine the proportions of Mn, Ni, and Si in the t3, t6, and t7 phases of the reactor pressure vessel steel.

[0028] S14: Determine the service temperature of the reactor pressure vessel steel.

[0029] S15: Based on the Mn, Ni, and Si ratios of the t3, t6, and t7 phases in the reactor pressure vessel steel determined in step S13, and the service temperature of the reactor pressure vessel steel determined in step S14, determine the chemical free energies of the t3, t6, and t7 phases in the reactor pressure vessel steel. In some embodiments, determining the elastic free energy caused by the precipitation of the t3, t6, and t7 phases in the reactor pressure vessel steel in step S10 may further include the following steps: S16: Determine the intrinsic strain tensors of the t3, t6, and t7 phases relative to the matrix phase, as well as the sequence parameters of the t3, t6, and t7 phases in the reactor pressure vessel steel.

[0030] S17: Determine the elastic stiffness tensor of the steel matrix phase of the reactor pressure vessel.

[0031] S18: Based on the intrinsic strain tensors of phases t3, t6, and t7 relative to the matrix phase determined in step S16, and the sequence parameters of phases t3, t6, and t7, determine the spatial distribution of the local effective intrinsic strain tensor of the reactor pressure vessel steel.

[0032] S19: Based on the elastic stiffness tensor of the matrix phase determined in step S17 and the spatial distribution of the local effective intrinsic strain tensor determined in step S18, determine the elastic free energy caused by the precipitation of t3, t6 and t7 phases in the reactor pressure vessel steel.

[0033] In this embodiment, by considering stress interference during the multiphase precipitation process, the spatial distribution of the local effective intrinsic strain tensor of reactor pressure vessel steel is determined using the intrinsic strain tensors of t3, t6, and t7 phases relative to the matrix phase, as well as the order parameters of t3, t6, and t7 phases. Based on this, combined with the elastic stiffness tensor of the matrix phase of reactor pressure vessel steel, it is beneficial to improve the degree of conformity between the determined elastic free energy caused by the precipitation of t3, t6, and t7 phases in reactor pressure vessel steel and the actual situation. This is beneficial to ensure that the total free energy of the subsequently determined five-element four-phase system can accurately reflect the energy contribution of different elements and different phases relative to the five-element four-phase system, thereby facilitating a more accurate prediction of the true morphological characteristics of each precipitated phase under stress interference.

[0034] In some embodiments, step S11 may further include the following steps: S111: Determine the interfacial energies of the t3, t6, and t7 phases in the matrix phase of reactor pressure vessel steel.

[0035] S112: Determine the size range of the t3, t6, and t7 phases in the reactor pressure vessel steel.

[0036] S113: Based on the size range of the t3 phase, t6 phase, and t7 phase in the reactor pressure vessel steel determined in step S112, determine the interface width in the five-element four-phase system composed of the five-element alloy of Fe, Cu, Mn, Ni, and Si, the t3 phase, the t6 phase, the t7 phase, and the matrix phase used to simulate the reactor pressure vessel steel.

[0037] S114: Based on the interfacial energies of the t3, t6, and t7 phases in the reactor pressure vessel steel determined in step S111, and the interfacial widths in the five-element four-phase system composed of the Fe, Cu, Mn, Ni, and Si five-element alloys, t3, t6, t7 phases, and matrix phase used to simulate the reactor pressure vessel steel determined in step S113, determine the gradient free energy coefficients between the matrix phase and the t3 phase, the gradient free energy coefficients between the matrix phase and the t6 phase, the gradient free energy coefficients between the matrix phase and the t7 phase, the gradient free energy coefficients between the t3 phase and the t6 phase, the gradient free energy coefficients between the t3 phase and the t7 phase, and the gradient free energy coefficients between the t6 phase and the t7 phase in the reactor pressure vessel steel.

[0038] This embodiment considers the interfacial energies of the t3, t6, and t7 phases in the reactor pressure vessel steel and the matrix phase, as well as the interfacial widths in the five-element four-phase system composed of the Fe, Cu, Mn, Ni, and Si alloys, the t3, t6, t7 phases, and the matrix phase used to simulate the reactor pressure vessel steel. This method determines the pairwise gradient free energy coefficients between the t3, t6, t7 phases, and the matrix phase in the reactor pressure vessel steel. This avoids tedious calculations, improves data accuracy, and thus effectively enhances simulation efficiency and feasibility while ensuring simulation accuracy.

[0039] In some embodiments, in step S20, the chemical free energies of the t3, t6, and t7 phases in the reactor pressure vessel steel, the elastic free energies caused by the precipitation of the t3, t6, and t7 phases in the reactor pressure vessel steel, the gradient free energies of the t3, t6, and t7 phases in the reactor pressure vessel steel, and the total free energy of the five-element four-phase system composed of the five-element alloy of Fe, Cu, Mn, Ni, and Si, the t3, t6, t7 phases, and the matrix phase, which incorporates the interfacial interactions of the t3, t6, t7 phases, and the matrix phase, conform to the following relationship: .

[0040] in, To disregard the free energies of the pentagonal alloy of Fe, Cu, Mn, Ni, and Si phases t3, t6, and t7, The chemical free energies of the t3, t6, and t7 phases in reactor pressure vessel steel are given. The elastic free energy caused by the precipitation of t3, t6, and t7 phases in reactor pressure vessel steel , The total free energy of a five-element four-phase system consisting of a five-element alloy of Fe, Cu, Mn, Ni, and Si, comprising the t3 phase, t6 phase, t7 phase, and matrix phase, with the interfacial interactions of the t3 phase, t6 phase, t7 phase, and matrix phase incorporated. This represents the gradient free energy of the t3, t6, and t7 phases in reactor pressure vessel steel.

[0041] In this embodiment, the relationship between chemical free energy, gradient free energy, elastic free energy, and the total free energy of the five-element four-phase system is specifically established. Without considering the free energy of the five-element alloy of Fe, Cu, Mn, Ni, and Si in the t3, t6, and t7 phases, the chemical free energy and gradient free energy of the t3, t6, and t7 phases in reactor pressure vessel steel, as well as the elastic free energy caused by the precipitation of the t3, t6, and t7 phases in reactor pressure vessel steel, are combined to determine the total free energy of the new five-element four-phase system by considering the interaction between the interfaces of different phases. This helps to further ensure the accuracy of the prediction of the specific precipitation time and morphology of the t3, t6, and t7 phases in reactor pressure vessel steel.

[0042] Among them, the free energies of the pentagonal alloys of Fe, Cu, Mn, Ni, and Si, without considering the t3, t6, and t7 phases, are those that can be determined by those skilled in the art.

[0043] In some embodiments, step S30 may further include the following steps: S31: Determine the molar volumes of the t3, t6, and t7 phases in the reactor pressure vessel steel.

[0044] S32: Determine the diffusion coefficients of Mn, Ni, and Si in the steel matrix phase of the reactor pressure vessel.

[0045] S33: Determine the interfacial energies of the t3, t6, and t7 phases in the matrix phase of the reactor pressure vessel steel, as well as the size range of the t3, t6, and t7 phases in the reactor pressure vessel steel.

[0046] S34: Based on the size range determined in step S33, determine the interface width in the five-element four-phase system composed of the five-element alloy of Fe, Cu, Mn, Ni, and Si, the t3 phase, the t6 phase, the t7 phase, and the matrix phase used to simulate reactor pressure vessel steel.

[0047] S35: Based on the interfacial energies of the t3, t6, and t7 phases in the matrix phase of the reactor pressure vessel steel determined in step S33, the interfacial widths in the five-element four-phase system composed of the five-element alloy of Fe, Cu, Mn, Ni, and Si, the t3, t6, t7 phases, and the matrix phase determined in step S34, the molar volumes of the t3, t6, and t7 phases in the reactor pressure vessel steel determined in step S31, and the diffusion coefficients of Mn, Ni, and Si in the matrix phase of the reactor pressure vessel steel determined in step S32, determine the interfacial mobility of the t3, t6, and t7 phases in the matrix phase of the reactor pressure vessel steel.

[0048] This embodiment considers the molar volumes of the t3, t6, and t7 phases in reactor pressure vessel steel, as well as the diffusion coefficients of Mn, Ni, and Si in the matrix phase. It also combines the interfacial energies of the t3, t6, and t7 phases in the matrix phase with the interfacial widths in the five-element four-phase system composed of the Fe, Cu, Mn, Ni, and Si five-element alloy, the t3, t6, t7 phases, and the matrix phase used to simulate reactor pressure vessel steel. This method determines the interfacial migration rates of the t3, t6, and t7 phases in the matrix phase of reactor pressure vessel steel with higher accuracy and efficiency. It helps to effectively improve the accuracy of the kinetic parameters driving element migration, thereby further ensuring the accuracy and feasibility of predicting the specific precipitation time and morphology of the t3, t6, and t7 phases in reactor pressure vessel steel.

[0049] In some embodiments, step S40 may further include the following steps: S41: Determine the content of Fe, Cu, Mn, Ni, and Si elements in reactor pressure vessel steel, as well as the sequence parameters of t3, t6, and t7 phases in reactor pressure vessel steel.

[0050] S42: Determine the diffusion coefficients of Cu, Mn, Ni, and Si elements in the matrix phase, and the diffusion coefficients of Mn, Ni, and Si elements in the t3, t6, and t7 phases, respectively.

[0051] S43: Based on the initial contents of Fe, Cu, Mn, Ni, and Si elements in the reactor pressure vessel steel determined in S41, the order parameters of the t3, t6, and t7 phases in the reactor pressure vessel steel, the diffusion coefficients of Cu, Mn, Ni, and Si elements in the matrix phase determined in S42, and the diffusion coefficients of Mn, Ni, and Si elements in the t3, t6, and t7 phases respectively, determine the alloy element migration rates of Fe, Cu, Mn, Ni, and Si elements at specific spatial locations and times.

[0052] S44: Based on the migration rates of alloying elements determined in S43 and the total free energy of the five-element four-phase system determined in S20, determine the distribution of Fe, Cu, Mn, Ni, and Si in reactor pressure vessel steel.

[0053] In this embodiment, the different diffusion coefficients of Fe, Cu, Mn, Ni, and Si elements in different phases of reactor pressure vessel steel are comprehensively considered to fully account for the driving forces experienced by the elements in different phases. This improves the accuracy of the determined migration rates of Fe, Cu, Mn, Ni, and Si elements at specific spatial locations and times. Based on this, the total free energy of the five-element four-phase system is combined to further ensure that the determined distribution of Fe, Cu, Mn, Ni, and Si in the reactor pressure vessel steel can reflect its actual service situation in the reactor. This helps to further ensure the accuracy of the prediction of the specific precipitation time and morphology of the t3, t6, and t7 phases in the reactor pressure vessel steel.

[0054] In some embodiments, in step S43, the initial contents of Fe, Cu, Mn, Ni, and Si elements in the reactor pressure vessel steel, the order parameters of the t3, t6, and t7 phases in the reactor pressure vessel steel, the diffusion coefficients of Cu, Mn, Ni, and Si elements in the matrix phase, the diffusion coefficients of Mn, Ni, and Si elements in the t3, t6, and t7 phases respectively, and the migration rates of Fe, Cu, Mn, Ni, and Si elements at specific spatial locations and times conform to the following relationships: .

[0055] in, Let k be the migration rate of the alloying element in space r and time t. Let k be the specific content of element k in space r and time t. This represents the initial content of potassium (k) in the reactor pressure vessel steel. Let K be the diffusion coefficient of element k in the matrix phase. Let K be the diffusion coefficient of element k in phase t3. Let K be the diffusion coefficient of element k in phase t6. Let be the diffusion coefficient of element k in phase t7, where k represents the five elements Fe, Cu, Mn, Ni, and Si; This represents the order parameter of the matrix phase in reactor pressure vessel steel. This represents the order parameter of the t3 phase in reactor pressure vessel steel. This refers to the order parameter of the t6 phase in reactor pressure vessel steel. denoted as t7, the sequence parameter of the t7 phase in the reactor pressure vessel steel, where r represents the specific spatial location, t represents time, R represents the ideal gas constant, and T represents temperature.

[0056] In this embodiment, by establishing the relationship between the initial content of elements, the content of t3, t6, and t7 phases, the diffusion coefficients of Cu, Mn, Ni, and Si elements in the matrix phase, the diffusion coefficients of Mn, Ni, and Si elements in the t3, t6, and t7 phases respectively, and the migration rates of Fe, Cu, Mn, Ni, and Si elements at specific spatial locations and times, it is beneficial to accurately determine the migration rates of Fe, Cu, Mn, Ni, and Si elements at specific spatial locations and times, thereby improving the accuracy of the distribution of Fe, Cu, Mn, Ni, and Si in reactor pressure vessel steel.

[0057] Specifically, in step S43, the migration rates of Fe, Cu, Mn, Ni, and Si alloying elements at specific spatial locations and times can be determined using the aforementioned relationships. When determining the migration rate of Cu, the diffusion coefficient of Cu in the matrix phase is considered. When determining the migration rates of alloying elements such as Mn, Ni, and Si, their diffusion coefficients in the matrix phase, t3 phase, t6 phase, and t7 phase, respectively, are considered. , , , , , , , as well as , , , .

[0058] In some embodiments, step S44 may further include the following steps: S441: Based on the total free energy of the five-element four-phase system consisting of the five-element alloy of Fe, Cu, Mn, Ni, Si, t3 phase, t6 phase, t7 phase, and matrix phase, determined in step S20, and the stability factor of the five-element four-phase system consisting of the five-element alloy of Fe, Cu, Mn, Ni, Si, t3 phase, t6 phase, t7 phase, and matrix phase, and the stability factor of the five-element four-phase system consisting of the five-element alloy of Fe, Cu, Mn, Ni, Si, t3 phase, t6 phase, t7 phase, and matrix phase, and the stability factor of the five-element four-phase system consisting of the five-element alloy of Fe, Cu, Mn, Ni, Si, t3 phase, t6 phase, t7 phase, and matrix phase, and the stability factor of the five-element four-phase system, determined in step S20, and the five-element four-phase system, and the five-element four-phase system, including the five-element alloy of Fe, Cu, Mn, Ni, Si, t3 phase, t6 phase, t7 phase, and matrix phase, including the five-element four-phase system ...

[0059] S442: Based on the stability factor of the five-element four-phase system determined in step S441, the total free energy of the five-element four-phase system determined in step S20, and the migration rates of Fe, Cu, Mn, Ni, and Si elements at specific spatial locations and times determined in step S43, determine the distribution of Fe, Cu, Mn, Ni, and Si in the reactor pressure vessel steel.

[0060] In this embodiment, the stability factor of the five-element four-phase system, considering the interaction between interfaces, is determined by the total free energy of the five-element four-phase system. This stability factor can accurately reduce the errors and numerical mistakes caused by large time steps, allowing for simulations with longer durations and larger time spans. By combining the total free energy of the five-element four-phase system with the migration rates of alloying elements Fe, Cu, Mn, Ni, and Si at specific spatial locations and times, and by comprehensively considering the factors affecting element segregation and precipitation—namely, the thermodynamic properties, stability, and migration rates of each element in the five-element four-phase system—the distribution of Fe, Cu, Mn, Ni, and Si in reactor pressure vessel steel can be accurately simulated. This further restores the actual situation in the late stage of reactor service, thereby effectively ensuring the prediction accuracy of the specific precipitation time and morphology of the t3, t6, and t7 phases in reactor pressure vessel steel.

[0061] Please see Figures 1-4 , Figure 1 The diagram shows the distribution of Cu in the reactor pressure vessel steel of an embodiment of this application at different times under irradiation conditions. Figure 2 The diagram shows the distribution of Mn in the reactor pressure vessel steel of an embodiment of this application at different times under irradiation conditions. Figure 3 The diagram shows the distribution of Ni in the reactor pressure vessel steel of an embodiment of this application at different times under irradiation conditions. Figure 4 This diagram illustrates the distribution of Si in the reactor pressure vessel steel of an embodiment of this application at different times under irradiation conditions. Figures 1-4 The figures, from left to right, show the distribution of Cu, Mn, Ni, and Si elements in reactor pressure vessel steel after irradiation for 1500 days, 2000 days, and 2200 days, respectively. As can be seen from the figures, under irradiation conditions, Cu, Mn, Ni, and Si elements tend to agglomerate and form clusters.

[0062] In some embodiments, step S50 may further include the following steps: S51: Based on the total free energy of the five-element four-phase system determined in step S20, determine the local phase transformation driving force for the precipitation of t3, t6, and t7 phases in the reactor pressure vessel steel.

[0063] S52: Based on the local phase transformation driving force determined in step S51 and the interfacial migration rates of the t3, t6, and t7 phases in the matrix phase of the reactor pressure vessel steel determined in step S30, determine the kinetic evolution rate of the t3, t6, and t7 phase sequence parameters over time.

[0064] S53: Based on the kinetic evolution rate of the t3, t6, and t7 phase sequence parameters over time determined in step S52, and the distribution of Fe, Cu, Mn, Ni, and Si in the reactor pressure vessel steel determined in step S40, determine the sequence parameter distribution of the t3, t6, and t7 phases at specific spatial locations under continuous time steps.

[0065] S54: Based on the sequence parameter distribution determined in S53, determine the specific precipitation time and morphology of the t3, t6, and t7 phases in the reactor pressure vessel steel.

[0066] In this embodiment, the local phase transformation driving force for the precipitation of t3, t6, and t7 phases in the reactor pressure vessel steel is determined by the total free energy of the five-element four-phase system. This strictly transforms the thermodynamic parameters of the five-element four-phase system into local phase transformation driving forces controlling the microscopic phase transformation process. Using the local phase transformation driving force and the interface migration rate determined in step S30, the kinetic evolution rate of the t3, t6, and t7 phase sequence parameters over time is determined. This strictly transforms the kinetic parameters into the kinetic evolution rate of the sequence parameters controlling the microscopic phase transformation process. By establishing a clear mapping path from macroscopic thermodynamics to microscopic kinetics, and based on this, the order parameter distribution is determined by combining the distribution of Fe, Cu, Mn, Ni, and Si. Based on this, the specific precipitation times and morphologies of the t3, t6, and t7 phases in reactor pressure vessel steel are determined, ensuring that the determined specific "precipitation times" have true physical meaning. In turn, this accurately reflects the kinetic competition mechanism and morphological evolution characteristics of the t3, t6, and t7 phases at different stages such as nucleation, growth, and coarsening, effectively improving prediction accuracy.

[0067] Please see Figure 5 and Figure 6 , Figure 5 The diagram shows the morphology of the t3 phase precipitation in reactor pressure vessel steel under low Mn content conditions according to an embodiment of this application. Figure 6 This image shows the t6 phase precipitation morphology of reactor pressure vessel steel under low Mn content conditions, according to an embodiment of this application. From... Figure 5 and Figure 6 A unique t6-t3 core-shell structure can be clearly observed. The t6 phase precipitates first and dominates, while a very thin t3 phase shell forms at the outer interface at the end of the t6 phase growth. After the appearance of the t3 phase, the volume expansion of the entire precipitated phase almost stops. This demonstrates the high precision and microscopic capture capability of the method provided in this application, and proves that the method can accurately capture and reproduce the dynamic solute depletion effect in complex multiphase systems, that is, the t6 phase consumes a large amount of Ni, leading to the relative enrichment of Mn at the interface, thereby inducing the formation of the t3 phase.

[0068] Please see Figures 7-9 , Figure 7The diagrams show the morphology of the t3 and t6 phases in reactor pressure vessel steel under high Mn content conditions according to embodiments of this application. Figure 8 The diagram shows the particle size distribution of the t3 phase in reactor pressure vessel steel with high Mn content, according to an embodiment of this application. Figure 9 This diagram shows the grain size distribution of the t6 phase in reactor pressure vessel steel with a high Mn content, according to an embodiment of this application. From... Figure 7 As can be seen, under high Mn content conditions, the previous core-shell structure is broken, and the t6 and t3 phases transform into a state of independent precipitation and random coexistence. This phenomenon is observed through... Figure 8 and Figure 9 The particle size distribution was further quantified. In the high-Mn system, the average particle size of the t3 phase was significantly larger than that of the t6 phase, and the particle size distribution curve of the t3 phase showed greater broadening, exhibiting a non-uniform size distribution phenomenon with both large and extremely small particles. This proves that the method provided in this application can sensitively and accurately quantify and predict the controlling effect of different alloying element concentrations on the competition mechanism of precipitates.

[0069] Regarding the embodiments of this application, it should also be noted that, without conflict, the embodiments of this application and the features in the embodiments can be combined with each other to obtain new embodiments.

[0070] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. The scope of protection of this application shall be determined by the scope of the claims.

Claims

1. A method for determining the specific precipitation time and morphology of a t3 phase, a t6 phase, and a t7 phase in a reactor pressure vessel steel composed of a five-component alloy of Fe, Cu, Mn, Ni, and Si, characterized by, It includes the following steps: ​ S10: Determine the chemical free energies of the t3, t6, and t7 phases in the reactor pressure vessel steel, the gradient free energies of the t3, t6, and t7 phases in the reactor pressure vessel steel, and the elastic free energies caused by the precipitation of the t3, t6, and t7 phases in the reactor pressure vessel steel. S20: Based on the chemical free energy, gradient free energy, and elastic free energy of the t3, t6, and t7 phases in the reactor pressure vessel steel determined in step S10, determine the total free energy of the five-element four-phase system consisting of the five-element alloy of Fe, Cu, Mn, Ni, and Si, the t3 phase, the t6 phase, the t7 phase, and the matrix phase, which incorporates the interfacial interactions of the t3 phase, the t6 phase, the t7 phase, and the matrix phase; S30: Determine the interfacial migration rates of the t3, t6, and t7 phases in the matrix phase of reactor pressure vessel steel; S40: Based on the total free energy of the five-element four-phase system determined in step S20, determine the distribution of Fe, Cu, Mn, Ni, and Si in the reactor pressure vessel steel; S50: Based on the total free energy of the five-element four-phase system determined in step S20, the interfacial migration rates of the t3, t6, and t7 phases in the matrix phase of the reactor pressure vessel steel determined in step S30, and the distribution of Fe, Cu, Mn, Ni, and Si in the reactor pressure vessel steel determined in step S40, determine the specific precipitation time and morphology of the t3, t6, and t7 phases in the reactor pressure vessel steel.

2. The method according to claim 1, characterized in that, In step S10, determining the gradient free energies of the t3, t6, and t7 phases in the reactor pressure vessel steel also includes the following steps: S11: Determine the gradient free energy coefficients of the matrix phase and t3 phase, the matrix phase and t6 phase, the matrix phase and t7 phase, the t3 phase and t6 phase, the t3 phase and t7 phase, and the t6 phase and t7 phase in the reactor pressure vessel steel. S12: Based on the gradient free energy coefficients of the matrix phase and t3 phase, the matrix phase and t6 phase, the matrix phase and t7 phase, the t3 phase and t6 phase, the t3 phase and t7 phase, and the t6 phase and t7 phase in the reactor pressure vessel steel determined in step S11, determine the gradient free energy of the t3 phase, t6 phase, and t7 phase in the reactor pressure vessel steel.

3. The method according to claim 2, characterized in that, In step S12, the gradient free energy coefficients of the matrix phase and t3 phase, the matrix phase and t6 phase, the matrix phase and t7 phase, the t3 phase and t6 phase, the t3 phase and t7 phase, the t6 phase and t7 phase, and the gradient free energies of the t3, t6, and t7 phases in the reactor pressure vessel steel conform to the following relationship: ， in, This represents the gradient free energy of the t3, t6, and t7 phases in the reactor pressure vessel steel. The gradient free energy coefficients of the matrix phase and the t3 phase are given. The gradient free energy coefficients of the matrix phase and the t6 phase are given. The gradient free energy coefficients of the matrix phase and the t7 phase are given. The gradient free energy coefficients of phases t3 and t6 are given. The gradient free energy coefficients of phases t3 and t7 are given. The gradient free energy coefficients of phases t6 and t7 are given. For the order parameter of the matrix phase, For the sequence parameter of phase t3, For the sequence parameter of phase t6, For the t7 phase sequence parameter.

4. The method according to claim 1, characterized in that, In step S10, determining the chemical free energies of the t3, t6, and t7 phases in the reactor pressure vessel steel also includes the following steps: S13: Determine the proportions of Mn, Ni, and Si in the t3, t6, and t7 phases of the reactor pressure vessel steel; S14: Determine the service temperature of the reactor pressure vessel steel; S15: Based on the Mn, Ni, and Si ratios of the t3, t6, and t7 phases in the reactor pressure vessel steel determined in step S13 and the service temperature of the reactor pressure vessel steel determined in step S14, determine the chemical free energies of the t3, t6, and t7 phases in the reactor pressure vessel steel.

5. The method according to claim 1, characterized in that, Step S10, which determines the elastic free energy caused by the precipitation of the t3, t6, and t7 phases in the reactor pressure vessel steel, also includes the following steps: S16: Determine the intrinsic strain tensors of the t3, t6, and t7 phases relative to the matrix phase, as well as the sequence parameters of the t3, t6, and t7 phases in the reactor pressure vessel steel; S17: Determine the elastic stiffness tensor of the steel matrix phase of the reactor pressure vessel; S18: Based on the intrinsic strain tensors of the t3 phase, t6 phase, and t7 phase relative to the matrix phase determined in step S16, and the order parameters of the t3 phase, t6 phase, and t7 phase, determine the spatial distribution of the local effective intrinsic strain tensor of the reactor pressure vessel steel. S19: Based on the elastic stiffness tensor of the matrix phase determined in step S17 and the spatial distribution of the local effective intrinsic strain tensor determined in step S18, determine the elastic free energy caused by the precipitation of t3, t6 and t7 phases in the reactor pressure vessel steel.

6. The method according to claim 2, characterized in that, Step S11 also includes the following steps: S111: Determine the interfacial energies of the t3, t6, and t7 phases in the matrix phase of the reactor pressure vessel steel; S112: Determine the size range of the t3 phase, t6 phase, and t7 phase in the reactor pressure vessel steel; S113: Based on the size range of the t3 phase, t6 phase, and t7 phase in the reactor pressure vessel steel determined in step S112, determine the interface width in the five-element four-phase system composed of the five-element alloy of Fe, Cu, Mn, Ni, and Si, the t3 phase, the t6 phase, the t7 phase, and the matrix phase used to simulate the reactor pressure vessel steel. S114: Based on the interfacial energies of the t3, t6, and t7 phases in the matrix phase of the reactor pressure vessel steel determined in step S111, and the interfacial widths in the five-element four-phase system composed of the Fe, Cu, Mn, Ni, and Si five-element alloy, t3, t6, t7 phases, and matrix phase determined in step S113, determine the gradient free energy coefficients between the matrix phase and the t3 phase, the gradient free energy coefficients between the matrix phase and the t6 phase, the gradient free energy coefficients between the matrix phase and the t7 phase, the gradient free energy coefficients between the t3 phase and the t6 phase, the gradient free energy coefficients between the t3 phase and the t7 phase, and the gradient free energy coefficients between the t6 phase and the t7 phase in the reactor pressure vessel steel.

7. The method according to claim 1, characterized in that, In step S20, the chemical free energies of the t3, t6, and t7 phases in the reactor pressure vessel steel, the gradient free energies of the t3, t6, and t7 phases in the reactor pressure vessel steel, the elastic free energies caused by the precipitation of the t3, t6, and t7 phases in the reactor pressure vessel steel, and the total free energy of the five-element four-phase system composed of the Fe, Cu, Mn, Ni, and Si five-element alloy, the t3, t6, t7 phases, and the matrix phase, which incorporates the interfacial interactions of the t3, t6, t7 phases, and the matrix phase, conform to the following relationship: ， in, To disregard the free energies of the pentagonal alloy of Fe, Cu, Mn, Ni, and Si phases t3, t6, and t7, The chemical free energies of the t3, t6, and t7 phases in the reactor pressure vessel steel are given. The elastic free energy caused by the precipitation of the t3, t6, and t7 phases in the reactor pressure vessel steel. , The total free energy is the total free energy of the five-element four-phase system consisting of the pentagonal alloy of Fe, Cu, Mn, Ni, and Si, the t3 phase, the t6 phase, the t7 phase, and the matrix phase, which incorporates the interfacial interactions of the t3 phase, the t6 phase, the t7 phase, and the matrix phase. This represents the gradient free energy of the t3, t6, and t7 phases in the reactor pressure vessel steel.

8. The method according to claim 1, characterized in that, Step S30 also includes the following steps: S31: Determine the molar volumes of the t3, t6, and t7 phases in the reactor pressure vessel steel; S32: Determine the diffusion coefficients of Mn, Ni, and Si in the steel matrix phase of the reactor pressure vessel; S33: Determine the interfacial energy of the t3, t6, and t7 phases in the matrix phase of the reactor pressure vessel steel, as well as the size range of the t3, t6, and t7 phases in the reactor pressure vessel steel; S34: Based on the size range determined in step S33, determine the interface width in the five-element four-phase system composed of the five-element alloy of Fe, Cu, Mn, Ni, and Si, the t3 phase, the t6 phase, the t7 phase, and the matrix phase used to simulate the reactor pressure vessel steel. S35: Based on the interfacial energies of the t3, t6, and t7 phases in the matrix phase of the reactor pressure vessel steel determined in step S33, the interfacial widths in the five-element four-phase system composed of the Fe, Cu, Mn, Ni, and Si five-element alloy, t3, t6, t7 phases, and matrix phase determined in step S34, the molar volumes of the t3, t6, and t7 phases in the reactor pressure vessel steel determined in step S31, and the diffusion coefficients of Mn, Ni, and Si in the matrix phase of the reactor pressure vessel steel determined in step S32, determine the interfacial mobility of the t3, t6, and t7 phases in the matrix phase of the reactor pressure vessel steel.

9. The method according to claim 1, characterized in that, Step S40 also includes the following steps: S41: Determine the content of Fe, Cu, Mn, Ni, and Si elements in the reactor pressure vessel steel, as well as the sequence parameters of the t3, t6, and t7 phases in the reactor pressure vessel steel; S42: Determine the diffusion coefficients of Cu, Mn, Ni, and Si elements in the matrix phase, and the diffusion coefficients of Mn, Ni, and Si elements in the t3, t6, and t7 phases, respectively; S43: Based on the initial contents of Fe, Cu, Mn, Ni, and Si elements in the reactor pressure vessel steel determined in S41, the order parameters of the t3, t6, and t7 phases in the reactor pressure vessel steel, the diffusion coefficients of Cu, Mn, Ni, and Si elements in the matrix phase determined in S42, and the diffusion coefficients of Mn, Ni, and Si elements in the t3, t6, and t7 phases respectively, determine the alloy element migration rates of Fe, Cu, Mn, Ni, and Si elements at specific spatial locations and times. S44: Based on the migration rate of the alloying elements determined in S43 and the total free energy of the five-element four-phase system determined in S20, determine the distribution of Fe, Cu, Mn, Ni, and Si in the reactor pressure vessel steel.

10. The method according to claim 9, characterized in that, In step S43, the initial contents of Fe, Cu, Mn, Ni, and Si elements in the reactor pressure vessel steel, the order parameters of the t3, t6, and t7 phases in the reactor pressure vessel steel, the diffusion coefficients of Cu, Mn, Ni, and Si elements in the matrix phase, the diffusion coefficients of Mn, Ni, and Si elements in the t3, t6, and t7 phases respectively, and the migration rates of Fe, Cu, Mn, Ni, and Si elements at specific spatial locations and times conform to the following relationships: ， in, Let k be the migration rate of the alloying element in space r and time t. Let k be the specific content of element k in space r and time t. This represents the initial content of potassium (k) in the reactor pressure vessel steel. Let K be the diffusion coefficient of element k in the matrix phase. Let K be the diffusion coefficient of element k in phase t3. Let K be the diffusion coefficient of element k in phase t6. Let be the diffusion coefficient of element k in phase t7, where k represents the five elements Fe, Cu, Mn, Ni, and Si; This represents the order parameter of the matrix phase in reactor pressure vessel steel. The t3 phase is the order parameter in the reactor pressure vessel steel. The t6 phase is the order parameter in reactor pressure vessel steel. The t7 phase is the sequence parameter in the reactor pressure vessel steel, r represents the specific spatial location, t represents the time, R represents the ideal gas constant, and T represents the temperature.

11. The method according to claim 9, characterized in that, Step S44 also includes the following steps: S441: Based on the total free energy of the five-element four-phase system consisting of the five-element alloy of Fe, Cu, Mn, Ni, Si, t3 phase, t6 phase, t7 phase, and matrix phase, determined in step S20, and the stability factor of the five-element four-phase system consisting of the five-element alloy of Fe, Cu, Mn, Ni, Si, t3 phase, t6 phase, t7 phase, and matrix phase, and the stability factor of the five-element four-phase system consisting of the five-element alloy of Fe, Cu, Mn, Ni, Si, t3 phase, t6 phase, t7 phase, and matrix phase, and the stability factor of the five-element four-phase system, determined in step S20, and the five-element alloy of Fe, Cu, Mn, Ni, Si, t3 phase, t6 phase, t7 phase, and matrix phase, and the stability factor of the five-element four-phase system, determined in step S20, and the five-element four-phase system, and the five-element four-phase system, including the five-element alloy of Fe, Cu, Mn, Ni, Si, t3 phase, t6 phase, t7 phase, and matrix phase, including the five-element four-phase system ... S442: Based on the stability factor of the five-element four-phase system determined in step S441, the total free energy of the five-element four-phase system determined in step S20, and the migration rates of the Fe, Cu, Mn, Ni, and Si elements at specific spatial locations and times determined in step S43, determine the distribution of Fe, Cu, Mn, Ni, and Si in the reactor pressure vessel steel.

12. The method according to claim 1, characterized in that, Step S50 also includes the following steps: S51: Based on the total free energy of the five-element four-phase system determined in step S20, determine the local phase transformation driving force for the precipitation of t3, t6, and t7 phases in the reactor pressure vessel steel; S52: Based on the local phase transformation driving force determined in step S51 and the interfacial migration rate of the t3, t6, and t7 phases in the reactor pressure vessel steel within the matrix phase determined in step S30, determine the kinetic evolution rate of the t3, t6, and t7 phase sequence parameters over time. S53: Based on the kinetic evolution rate of the sequence parameters of phases t3, t6, and t7 over time as determined in step S52, and the distribution of Fe, Cu, Mn, Ni, and Si in the reactor pressure vessel steel as determined in step S40, determine the sequence parameter distribution of phases t3, t6, and t7 at specific spatial locations under continuous time steps. S54: Based on the sequence parameter distribution determined in S53, determine the specific precipitation time and morphology of the t3, t6, and t7 phases in the reactor pressure vessel steel.

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