Structure inspection device and method

Abstract

To provide a structure inspection system and method capable of precisely estimating the occurrence of stress corrosion cracking.SOLUTION: The structure inspection system includes: a stress loading direction estimation unit that estimates macroscopic stress loading direction acting on a structure; a collective tissue measuring unit that measures a collective tissue of the structure; a crystal orientation analysis unit that analyzes the crystal orientation of the structure based on the macroscopic stress loading direction and the collective tissue; a microscopic stress estimation unit that estimates the microscopic stress based on the crystal orientation; and a probability of stress corrosion cracking occurrence estimation unit that estimates the probability of stress corrosion cracking in the structure based on the magnitude of the microscopic stress.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a structure inspection device. [Background technology]

[0002] When evaluating the occurrence of damage to a structure, for example, the occurrence of stress corrosion cracking (SCC) in the structure is evaluated. Conventional evaluation methods estimate the stress in a target part of the structure through numerical analysis, experiments, etc., and predict the SCC initiation life and propagation life based on the known relationship between stress and SCC initiation time and the relationship between stress and crack propagation rate. Examples of such conventional structure evaluation methods include those described in the following patent documents. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-175563 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-130588 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional structural evaluation methods evaluate the occurrence of stress corrosion cracking based on the macroscopic stress acting on the structure, but it is difficult to accurately evaluate the occurrence of stress corrosion cracking based solely on the macroscopic stress acting on the structure.

[0005] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a structure inspection device and method that enable the occurrence of stress corrosion cracking to be estimated with high accuracy. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the structure inspection device of the present disclosure includes a stress load direction estimation unit that estimates the macroscopic stress load direction acting on the structure, a texture measurement unit that measures the texture of the structure, a crystal orientation analysis unit that analyzes the crystal orientation of the structure based on the macroscopic stress load direction and the texture, a microscopic stress estimation unit that estimates microscopic stress based on the crystal orientation, and a stress corrosion cracking occurrence probability estimation unit that estimates the probability of stress corrosion cracking occurrence in the structure based on the magnitude of the microscopic stress.

[0007] In addition, the method for inspecting a structure disclosed herein includes the steps of estimating a direction of macroscopic stress applied to the structure, measuring the texture of the structure, analyzing the crystal orientation of the structure based on the direction of macroscopic stress applied and the texture, estimating microscopic stress based on the crystal orientation, and estimating the probability of occurrence of stress corrosion cracking in the structure based on the magnitude of the microscopic stress. [Effects of the Invention]

[0008] According to the structure inspection device and method disclosed herein, the occurrence of stress corrosion cracking can be estimated with high accuracy. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the structure inspection system. [Figure 2] FIG. 2 is a schematic diagram showing a method for measuring texture in a structure. [Figure 3] FIG. 3 is a graph showing stress versus the degree of integration of the slip surface. [Figure 4] FIG. 4 is a graph showing the probability of SCC occurrence versus the small von Mises equivalent stress. [Figure 5] FIG. 5 is a flowchart showing the structure inspection method of the first embodiment. [Figure 6] FIG. 6 is a flowchart showing a structure inspection method according to the second embodiment. [Figure 7]FIG. 7 is a flowchart showing a structure inspection method according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes configurations that combine the embodiments. Furthermore, the components in the embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially identical, and those that are within the so-called equivalent range.

[0011] [First embodiment] In the following embodiments, the structure is described as being applied to a pressure vessel, piping, or the like that constitutes a nuclear reactor. Therefore, the structure is made of, for example, a nickel-based alloy or austenitic stainless steel. However, the structure is not limited to the components of a nuclear reactor, and the material is not limited to a nickel-based alloy or austenitic stainless steel.

[0012] <Inspection system> FIG. 1 is a schematic diagram showing the structure inspection system.

[0013] As shown in FIG. 1, a structure inspection system (hereinafter simply referred to as an inspection system) 10 includes an inspection device 11, an operation unit 12, a detection device 13, a storage unit 14, and an output unit 15.

[0014] The inspection device 11 estimates the probability of occurrence of stress corrosion cracking in a structural member. The inspection device 11 is a control device. The control device as the inspection device 11 is a controller, and is realized by, for example, a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) executing various programs stored in the storage unit 214 using RAM as a working area.

[0015] The operation unit 12 can be operated by an operator to input various commands and various data to the inspection device 11. The operation unit 12 is, for example, a keyboard or a touch-type display. The detection device 13, which will be described later, measures the metal structure of a specific location on the structure. The memory unit 14 stores various programs executed by the inspection device 11. The various programs include a program for diagnosing the occurrence of stress corrosion cracking in the structure. The memory unit 14 also stores microscopic stress maps and stress corrosion cracking occurrence probability determination maps for each material required for diagnosis by the inspection device 11. The output unit 15 can output the processing contents of the inspection device 11. The output unit 15 is, for example, a monitor or a printer.

[0016] <Inspection equipment> Typical structural inspection methods estimate the occurrence of stress corrosion cracking based on the macroscopic stress acting on the structure. However, it has been confirmed that the occurrence of stress corrosion cracking is caused by local stresses that occur at grain boundaries, etc. In other words, the relationship between the microscopic stresses that occur, which reflect the material structure that makes up the structure, and the probability of stress corrosion cracking occurring has been experimentally obtained. For example, the probability of stress corrosion cracking occurring increases at grain boundaries where microscopic stresses that exceed 20% of the macroscopic stress occurring in the structure occur.

[0017] They discovered that microscopic stress depends on the texture of the material. By changing the crystal orientation and examining how microscopic stress occurs when a certain macroscopic stress is applied, they found that in metallic materials with a specific crystal structure, microscopic stress is low when a specific crystal plane is oriented in the direction of tension (or compressive stress). For example, microscopic stress is low in materials in which the crystal orientation is largely oriented in the normal direction of the slip plane in the direction of tension (or compressive stress).

[0018] In this embodiment, based on such knowledge, local stress is estimated from the results of measuring the texture of the material, and the probability of occurrence of stress corrosion cracking is quantitatively estimated.

[0019] Figure 2 is a schematic diagram showing a method for measuring texture in a structure, Figure 3 is a graph showing stress versus slip plane integration, and Figure 4 is a graph showing the SCC occurrence probability versus micro-Mises equivalent stress.

[0020] As shown in FIG. 1, the inspection device 11 includes a stress load direction estimation unit 21, a texture measurement unit 22, a crystal orientation analysis unit 23, a microscopic stress estimation unit 24, and a stress corrosion cracking occurrence probability estimation unit 25.

[0021] As shown in FIGS. 1 and 2, a pipe 101 as a structure is arranged along an axis O. Note that the structure is not limited to the pipe 101. The stress load direction estimation unit 21 estimates the macroscopic stress load direction acting on the pipe 101. Specifically, the stress load direction estimation unit 21 estimates the macroscopic stress load direction acting on the pipe 101 by material mechanics calculation or the finite element method. For example, since a pressure fluid flows inside the pipe 101, a radial pressure acts on the pipe 101 from the pressure fluid. Therefore, a macroscopic stress that extends in the circumferential direction acts on the pipe 101, and the macroscopic stress load direction is the circumferential direction.

[0022] Texture measurement unit 22 measures the texture of pipe 101. Specifically, texture measurement unit 22 performs texture measurement on the outer peripheral surface of pipe 101 by X-ray diffraction using the back reflection method. Texture measurement unit 22 has X-ray source 31, slit plate 32, and detector 33. When X-ray source 31 irradiates X-rays, some of the X-rays pass through slit holes in slit plate 32 and are irradiated as slit X-rays onto measurement range 102 on the outer peripheral surface of pipe 101. Detector 33 detects the X-rays reflected from measurement range 102 and determines Miller indices (orientation indices) of the texture in measurement range 102.

[0023] As shown in Figure 1, the crystal orientation analysis unit 23 analyzes the crystal orientation of the pipe 101 based on the macroscopic stress load direction and texture. The crystal orientation analysis unit 23 estimates the concentration, which is the proportion of crystal orientations in the normal direction of the slip plane in the crystal structure among crystal orientations along the direction (axial center O direction) perpendicular to the macroscopic stress load direction (circumferential direction). In this case, the crystal orientation analysis unit 23 determines the concentration as the volume fraction of crystals in the normal direction of the slip plane within a predetermined angle based on the direction (axial center O direction) perpendicular to the macroscopic stress load direction.

[0024] The piping 101 has a face-centered cubic lattice crystal structure. A face-centered cubic lattice structure is a crystal lattice in which the same type of particles are arranged at the vertices and the center of each face of a unit cell, the smallest unit of a crystal's periodic structure. Metallic materials with a face-centered cubic lattice structure include aluminum (Al), copper (Cu), and gold (Au). Structural materials that correspond to this structure include austenitic stainless steel and nickel-based alloys. Plastic deformation of metallic materials is a slip deformation caused by the movement of atoms due to dislocation motion, and they have slip planes. For example, in a face-centered cubic lattice structure, the slip plane is a plane represented by Miller indices {111}. The Miller indices {hkl}, which represent a plane, are expressed as h, k, and l, respectively, and are the reciprocal of the intercept of a plane in a crystal that intersects the coordinate axes X, Y, and Z, divided by the atomic spacing. When a metallic material undergoes deformation along its respective slip planes, local stress (microstress) is generated between adjacent crystal grains.

[0025] In other words, when estimating the occurrence of cracks in the stress load direction (circumferential direction) of the metal material of the pipe 101, which has a face-centered cubic lattice structure, the crystal orientation analysis unit 23 defines the volume fraction of crystals whose normal direction to the slip plane {111} is oriented within a predetermined angle with the direction (axial center O direction) perpendicular to the stress load direction (circumferential direction) as a characteristic quantity of the pipe 101, and defines it as the concentration degree of the slip plane {111}.

[0026] Here, the predetermined angle is preferably 15 degrees, which is the angle of a high-angle grain boundary, but the predetermined angle is not limited to this angle. Here, the predetermined angle is used because it is the misorientation that is a condition for a random grain boundary, but it may be in the range of, for example, 5 degrees to 30 degrees, and may be set appropriately depending on the type of metal material, the application environment, etc.

[0027] In addition, when the stress load direction of the metal material of the pipe 101 is the direction of the axis O and the occurrence of a crack in the direction of the axis O is estimated, the crystal orientation analysis unit 23 defines the volume fraction of crystals whose slip plane {111} is oriented within a predetermined angle with the direction (circumferential direction) perpendicular to the stress load direction (direction of the axis O) as a feature of the pipe 101 and as the accumulation degree of the slip plane {111}.

[0028] Furthermore, when the crystal structure of the pipe 101 is a body-centered cubic lattice structure, the body-centered cubic lattice structure is a crystal lattice in which particles of the same type are arranged at each vertex of a solid and at the center of the solid. Metal materials having a body-centered cubic lattice structure include iron (Fe), chromium (Cr), and molybdenum (Mo). The body-centered cubic lattice structure has slip planes {111}, {112}, and {123}. As described above, the crystal orientation analysis unit 23 estimates the degree of integration using the slip planes {110}, {112}, and {123}.

[0029] The microscopic stress estimation unit 24 estimates the microscopic stress based on the crystal orientation. The microscopic stress estimation unit 24 estimates the microscopic stress based on the integration degree analyzed by the crystal orientation analysis unit 23. In this case, a microscopic stress map showing the microscopic stress relative to the integration degree is set in advance for each constituent material of the pipe 101, and the microscopic stress estimation unit 24 estimates the microscopic stress using the integration degree and the microscopic stress map.

[0030] Figure 3 shows a microstress map showing the microstress versus the integration level. As shown in Figure 3, the horizontal axis represents the integration level of the {111} slip plane, and the vertical axis represents the micro-Mises equivalent stress (microstress), which is the stress value corresponding to the cumulative 95% of the minimum value of the distributed microstress. The microstress map was created by performing numerical analysis using the crystal plasticity finite element method (FEM) with a polycrystalline model with various crystal orientations. The microstress map shows the relationship between the microstress value and the SCC probability, as described below, based on experimental data. Specifically, when the microstress is close to the macrostress σb, the SCC probability is low, and when the microstress exceeds 1.2 times the macrostress σb (1.2σb), the SCC probability is estimated to be high.

[0031] In the microscopic stress map, as the degree of integration increases, the microscopic stress decreases and approaches the macroscopic generated stress. Conversely, as the degree of integration decreases, the microscopic stress increases and moves away from the macroscopic generated stress. Experiments and analysis have shown that focusing on the {111} slip plane is sufficient. In the pipe 101, which has a face-centered cubic lattice structure, the {111} slip plane is aligned with the normal direction. In other words, the higher the degree of integration of the {111} slip plane, the lower the microscopic stress. This crystallographic interpretation means that crystal slip is less likely to occur, making it less likely for one crystal grain to intrude into an adjacent crystal grain. Conversely, the lower the degree of integration of the {111} slip plane, the higher the microscopic stress. This crystallographic interpretation means that crystal slip is more likely to occur, making it more likely for one crystal grain to intrude into an adjacent crystal grain.

[0032] The microscopic stress estimation unit 24 applies the integration degree analyzed by the crystal orientation analysis unit 23 to a microscopic stress map, and obtains the microscopic stress relative to the integration degree.

[0033] The stress corrosion cracking occurrence probability estimation unit 25 estimates the probability of stress corrosion cracking occurrence in the piping 101 based on the magnitude of the microscopic stress. In this case, a stress corrosion cracking occurrence probability determination map showing the probability of stress corrosion cracking occurrence relative to the microscopic stress is set in advance for each constituent material of the piping 101, and the stress corrosion cracking occurrence probability estimation unit 25 estimates the probability of stress corrosion cracking occurrence using the microscopic stress and the stress corrosion cracking occurrence probability determination map.

[0034] Figure 4 is a stress corrosion cracking probability determination map for a nickel-based alloy under a specified environment. As shown in Figure 4, the horizontal axis represents the micro-Mises equivalent stress (microstress), and the vertical axis represents the SCC occurrence probability. When the microscopic stress is close to the macroscopic stress σb, the SCC occurrence probability is low. On the other hand, when the microscopic stress exceeds 1.2 times the macroscopic stress σb (1.2σb), the SCC occurrence probability increases sharply. The stress corrosion cracking occurrence probability estimation unit 25 applies the microscopic stress calculated by the microscopic stress estimation unit 24 to the stress corrosion cracking occurrence probability determination map to determine the SCC occurrence probability for the microscopic stress.

[0035] Therefore, as shown in Figure 3, the inspection device 11 diagnoses that the probability (risk) of SCC occurrence is high when the slip plane {111} integration rate is less than 50% from the microscopic stress map. When the slip plane {111} integration rate is less than 50%, the SCC occurrence probability can be quantitatively estimated from the stress corrosion cracking occurrence probability determination map, as shown in Figure 4. Therefore, depending on the level of the SCC occurrence probability, measures such as strengthened inspections, stress reduction work, and pipe replacement can be taken.

[0036] The stress corrosion cracking probability assessment map is experimental data for a specific metallic material under a specific environment, and it is preferable to obtain experimental data for each specific environment or for each specific metallic material. In this case, the assessment value for the SCC probability was set to 1.2 times the macroscopic stress σb (1.2σb), i.e., a slip plane {111} integration degree of 50%, but this value is not limitative. Depending on the environment and material, the assessment value can be set appropriately within a range of slip plane {111} integration degree of 5% to 50%, for example.

[0037] <Testing method> FIG. 5 is a flowchart showing the structure inspection method of the first embodiment.

[0038] The structure inspection method includes the steps of estimating the macroscopic stress load direction acting on the pipe 101, measuring the texture of the pipe 101, analyzing the crystal orientation of the pipe 101 based on the macroscopic stress load direction and the texture, estimating microscopic stress based on the crystal orientation, and estimating the probability of stress corrosion cracking occurring in the pipe 101 based on the magnitude of the microscopic stress.

[0039] 1 and 5, in step S11, stress load direction estimation unit 21 estimates the macroscopic stress load direction acting on pipe 101 by material mechanics calculation or finite element method. For example, the macroscopic stress load direction of pipe 101 is the circumferential direction. In step S12, texture measurement unit 22 performs texture measurement on the outer surface of pipe 101 by X-ray diffraction using the back reflection method, and determines Miller indices for the texture in measurement range 102.

[0040] In step S13, the crystal orientation analysis unit 23 calculates the volume fraction of crystals in the normal direction of the slip plane {111} within a predetermined angle (e.g., 15 degrees) with respect to the direction perpendicular to the macroscopic stress load direction (axis O direction) as the integration degree. In step S14, the microscopic stress estimation unit 24 estimates the microscopic stress using a microscopic stress map based on the integration degree analyzed by the crystal orientation analysis unit 23. In step S15, the stress corrosion cracking occurrence probability estimation unit 25 estimates the SCC occurrence probability using a stress corrosion cracking occurrence probability determination map based on the microscopic stress calculated by the microscopic stress estimation unit 24.

[0041] [Second embodiment] Fig. 6 is a flowchart showing a structure inspection method according to the second embodiment. The basic configuration of the second embodiment is the same as that of the first embodiment described above, and will be described using Fig. 1. Members having the same functions as those in the first embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0042] As shown in FIG. 1, the inspection device 11 includes a stress load direction estimation unit 21, a texture measurement unit 22, a crystal orientation analysis unit 23, a microscopic stress estimation unit 24, and a stress corrosion cracking occurrence probability estimation unit 25.

[0043] The stress load direction estimation unit 21 is the same as in the first embodiment. The texture measurement unit 22 measures the texture of the pipe 101. Specifically, the texture measurement unit 22 collects a sample from the outer peripheral surface of the pipe 101 and measures the texture by performing backscattered electron diffraction on the collected sample. That is, the texture measurement unit 22 measures the orientation distribution of crystal grains in the texture of the measurement range 102 by backscattered electron diffraction on the sample. The crystal orientation analysis unit 23, the microscopic stress estimation unit 24, and the stress corrosion cracking occurrence probability estimation unit 25 are the same as in the first embodiment.

[0044] 1 and 6, in step S21, stress load direction estimation unit 21 estimates the macroscopic stress load direction acting on pipe 101 by material mechanics calculation or the finite element method. For example, the macroscopic stress load direction of pipe 101 is the circumferential direction. In step S22, texture measurement unit 22 measures the orientation distribution of crystal grains in the texture of measurement range 102 by backscattered electron diffraction of a sample taken from the outer circumferential surface of pipe 101.

[0045] In step S23, the crystal orientation analysis unit 23 calculates the volume fraction of crystals in the normal direction of the slip plane {111} within a predetermined angle (e.g., 15 degrees) with respect to the direction perpendicular to the macroscopic stress load direction (axis O direction) as the integration degree. In step S24, the microscopic stress estimation unit 24 estimates the microscopic stress using a microscopic stress map based on the integration degree analyzed by the crystal orientation analysis unit 23. In step S25, the stress corrosion cracking occurrence probability estimation unit 25 estimates the SCC occurrence probability using a stress corrosion cracking occurrence probability determination map based on the microscopic stress calculated by the microscopic stress estimation unit 24.

[0046] [Third embodiment] Fig. 7 is a flowchart showing a structure inspection method according to the third embodiment. The basic configuration of the third embodiment is the same as that of the first embodiment described above, and will be described using Fig. 1. Members having the same functions as those in the first embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0047] As shown in FIG. 1, the inspection device 11 includes a stress load direction estimation unit 21, a texture measurement unit 22, a crystal orientation analysis unit 23, a microscopic stress estimation unit 24, and a stress corrosion cracking occurrence probability estimation unit 25.

[0048] The stress load direction estimation unit 21 is the same as in the first embodiment. The texture measurement unit 22 measures the texture of the pipe 101. Specifically, the texture measurement unit 22 collects a sample from the outer peripheral surface of the pipe 101 and measures the texture by performing backscattered electron diffraction on the collected sample. That is, the texture measurement unit 22 measures the orientation distribution of crystal grains in the texture of the measurement range 102 by backscattered electron diffraction on the sample. The crystal orientation analysis unit 23 analyzes the crystal orientation of the texture measured by the texture measurement unit 22. The microscopic stress estimation unit 24 analyzes the crystal orientation analyzed by the crystal orientation analysis unit 23 using a crystal plasticity finite element method to estimate microscopic stress. The stress corrosion cracking occurrence probability estimation unit 25 is the same as in the first embodiment.

[0049] 1 and 7, in step S31, stress load direction estimation unit 21 estimates the macroscopic stress load direction acting on pipe 101 by material mechanics calculation or the finite element method. For example, the macroscopic stress load direction of pipe 101 is the circumferential direction. In step S32, texture measurement unit 22 measures the orientation distribution of crystal grains in the texture of measurement range 102 by backscattered electron diffraction of a sample taken from the outer circumferential surface of pipe 101.

[0050] In step S33, crystal orientation analysis unit 23 analyzes the crystal orientation of the texture measured by texture measurement unit 22. In step S34, microscopic stress estimation unit 24 estimates microscopic stress by analyzing the crystal orientation analyzed by crystal orientation analysis unit 23 using a crystal plasticity finite element method. In step S35, stress corrosion cracking occurrence probability estimation unit 25 estimates the SCC occurrence probability using a stress corrosion cracking occurrence probability determination map based on the microscopic stress determined by microscopic stress estimation unit 24.

[0051] [Effects of this embodiment] The structure inspection device of the first embodiment includes a stress load direction estimation unit 21 that estimates the macroscopic stress load direction acting on a pipe (structure) 101, a texture measurement unit 22 that measures the texture of the pipe 101, a crystal orientation analysis unit 23 that analyzes the crystal orientation of the pipe 101 based on the macroscopic stress load direction and the texture, a microscopic stress estimation unit 24 that estimates microscopic stress based on the crystal orientation, and a stress corrosion cracking occurrence probability estimation unit 25 that estimates the probability of stress corrosion cracking occurring in the pipe 101 based on the magnitude of the microscopic stress.

[0052] The structure inspection device according to the first aspect estimates the microscopic stress acting on the pipe 101, and estimates the probability of occurrence of stress corrosion cracking in the pipe 101 based on the magnitude of the estimated microscopic stress. Therefore, it is possible to estimate the occurrence of stress corrosion cracking with high accuracy.

[0053] In the structure inspection device according to the second aspect, the crystal orientation analysis unit 23 estimates the accumulation index, which is the proportion of crystal orientations in the normal direction to the slip plane in the crystal structure among the crystal orientations in the normal direction perpendicular to the macroscopic stress load direction, and the microscopic stress estimation unit 24 estimates the microscopic stress based on the accumulation index. When a metal material is displaced and deformed in the slip plane direction, microscopic stress occurs as a localized stress. Therefore, the lower the accumulation index, which is the proportion of crystal orientations in the normal direction to the slip plane in the crystal structure, the higher the microscopic stress. Therefore, by using the accumulation index of the slip plane, the microscopic stress can be estimated with high accuracy.

[0054] In the structure inspection device according to the third aspect, the crystal orientation analysis unit 23 determines the density as the volume fraction of crystals in the normal direction of the slip plane within a predetermined angle set in advance with respect to the direction orthogonal to the macroscopic stress load direction, thereby enabling the density of the slip plane to be appropriately estimated.

[0055] In the structure inspection device according to the fourth aspect, a microscopic stress map showing microscopic stress relative to the integration degree is set in advance for each constituent material of the pipe 101, and the microscopic stress estimation unit 24 estimates the microscopic stress using the integration degree and the microscopic stress map. This makes it possible to estimate the microscopic stress easily and with high accuracy.

[0056] In the structure inspection device according to the fifth aspect, texture measurement unit 22 measures the texture by X-ray diffraction of pipe 101 or backscattered electron diffraction of a sample collected from pipe 101. This makes it possible to easily measure the texture of pipe 101.

[0057] In the structure inspection device according to the sixth aspect, texture measurement unit 22 measures the texture by backscattered electron diffraction of a sample taken from pipe 101, crystal orientation analysis unit 23 analyzes the crystal orientation of the texture, and microscopic stress estimation unit 24 analyzes the crystal orientation by the crystal plasticity finite element method to estimate microscopic stress. This makes it possible to estimate microscopic stress without using the degree of accumulation of slip planes, thereby simplifying the processing.

[0058] In the structure inspection device according to the seventh aspect, a stress corrosion cracking occurrence probability determination map showing the probability of stress corrosion cracking occurrence relative to microscopic stress is set in advance for each constituent material of the piping 101, and the stress corrosion cracking occurrence probability estimation unit 25 estimates the probability of stress corrosion cracking occurrence using the microscopic stress and the stress corrosion cracking occurrence probability determination map. This makes it possible to estimate the probability of stress corrosion cracking occurrence easily and with high accuracy.

[0059] The structure inspection method according to the eighth aspect includes the steps of estimating the direction of macroscopic stress applied to a pipe (structure) 101, measuring the texture of the pipe 101, analyzing the crystal orientation of the pipe 101 based on the macroscopic stress direction and the texture, estimating microscopic stress based on the crystal orientation, and estimating the probability of occurrence of stress corrosion cracking in the pipe 101 based on the magnitude of the microscopic stress. This allows the occurrence of stress corrosion cracking to be estimated with high accuracy. [Explanation of symbols]

[0060] 10 Structural Inspection Systems 11 Inspection equipment 12 Control section 13 Detection equipment 14 Storage section 15 Output section 21 Stress load direction estimation section 22 Texture measurement section 23 Crystal orientation analysis department 24 Microscopic stress estimation section 25 Stress corrosion cracking probability estimation section 31 X-ray source 32 Slit plate 33 Detector 101 Piping (Structures) 102 measurement range

Claims

1. a stress load direction estimation unit that estimates a macroscopic stress load direction acting on the structure; a texture measurement unit for measuring the texture of the structure; a crystal orientation analysis unit that analyzes the crystal orientation of the structure based on the macroscopic stress loading direction and the texture; a microscopic stress estimation unit that estimates microscopic stress based on the crystal orientation; a stress corrosion cracking occurrence probability estimation unit that estimates the probability of stress corrosion cracking occurring in the structure based on the magnitude of the microscopic stress; A structure inspection device comprising:

2. The crystal orientation analysis unit estimates an accumulation degree, which is a ratio of crystal orientations in a normal direction of a slip plane in a crystal structure to crystal orientations along a direction orthogonal to the macroscopic stress load direction, and the microscopic stress estimation unit estimates the microscopic stress based on the accumulation degree. The structure inspection device according to claim 1 .

3. the crystal orientation analysis unit defines the volume fraction of crystals in the normal direction of the slip plane within a predetermined angle set in advance with respect to a direction orthogonal to the macroscopic stress load direction as the degree of accumulation; The structure inspection device according to claim 2.

4. a microscopic stress map representing the microscopic stress relative to the integration degree is set in advance for each constituent material of the structure, and the microscopic stress estimation unit estimates the microscopic stress using the integration degree and the microscopic stress map; The structure inspection device according to claim 3.

5. the texture measurement unit measures the texture by X-ray diffraction of the structure or backscattered electron diffraction of a sample taken from the structure. The structure inspection device according to any one of claims 1 to 4.

6. the texture measurement unit measures the texture by backscattered electron diffraction of a sample taken from the structure, the crystal orientation analysis unit analyzes the crystal orientation of the texture, and the microscopic stress estimation unit analyzes the crystal orientation by a crystal plasticity finite element method to estimate the microscopic stress. The structure inspection device according to claim 1 .

7. a stress corrosion cracking occurrence probability determination map showing the stress corrosion cracking occurrence probability for the microscopic stress is set in advance for each constituent material of the structure, and the stress corrosion cracking occurrence probability estimation unit estimates the stress corrosion cracking occurrence probability using the microscopic stress and the stress corrosion cracking occurrence probability determination map; The structure inspection device according to any one of claims 1 to 6.

8. A step of estimating a macroscopic stress load direction acting on the structure; measuring the texture of the structure; analyzing the crystal orientation of the structure based on the macroscopic stress loading direction and the texture; estimating microstress based on the crystal orientation; a step of estimating the probability of occurrence of stress corrosion cracking in the structure based on the magnitude of the microscopic stress; A method for inspecting a structure having the above structure.

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