JP4851993B2 - Stress corrosion cracking test method - Google Patents

Description

  The present invention relates to a stress corrosion cracking test method for suitably acquiring stress corrosion cracking data relating to stress corrosion cracking (SCC) occurring on the surface of a specimen.

  For example, in a nuclear power plant, stress corrosion cracking occurs in in-core equipment in a boiling water reactor, which threatens structural integrity. For this reason, the test method for acquiring the stress corrosion crack generation data efficiently is an examination subject.

  In general, the stress corrosion cracking test is performed with a set of data on the relationship between the immersion time in the test environment until cracking occurs (that is, the cracking life), the strain at the cracking position, and the size of the crack. This is a test to acquire crack occurrence data. In this stress corrosion crack occurrence test, one set of stress corrosion crack occurrence data is acquired for each specimen.

  That is, the conventional stress corrosion cracking test method is a test in a state where uniform strain is generated in the test body, or a test focusing only on the maximum strain generated in the test body. The stress corrosion crack occurrence data is about one set.

  For example, in the stress corrosion cracking generation test in which uniform strain is generated in the specimen, a jig 3 having a curved surface 2 having a constant curvature radius R is prepared as shown in FIG. The test body 1 is brought into close contact and fixed, and the same strain generated in the test body 1 is measured by a strain gauge 4 installed at an arbitrary position of the test body 1, and the stress per one test body 1 is measured. One set of corrosion cracking data has been acquired.

  In addition, the stress corrosion cracking generation test for generating uniform strain on the test body is performed by bending the test body and engaging both ends thereof with fasteners as described in Patent Document 1, so that the test body is uniform. It has also been proposed to obtain a stress corrosion crack occurrence data by generating a large strain and measuring the strain with a strain gauge installed at an arbitrary position of the specimen. Also in this case, one set of stress corrosion cracking data is obtained for one test specimen.

On the other hand, in the stress corrosion cracking test focusing on only the maximum strain generated in the test body 1, for example, as shown in FIG. 13, both ends of the test body 1 are supported by a pair of support parts 5. A force F is applied to the central position in the direction, and the maximum strain generated at the position where the force F is applied is measured by the strain gauge 6 to obtain stress corrosion crack occurrence data. In this case as well, one set of stress corrosion cracking data is acquired for one specimen 1.
JP 2006-258500 A

  However, since the stress corrosion crack occurrence data varies widely, it is necessary to statistically evaluate the obtained data, which requires a large amount of data. However, a test method for efficiently acquiring such a large amount of data has not yet been established. For this reason, in order to acquire a lot of stress corrosion crack occurrence data, there is a problem that it is necessary to repeatedly perform the stress corrosion crack occurrence test with a great amount of test time.

  An object of the present invention is to provide a stress corrosion cracking test method capable of acquiring a plurality of stress corrosion cracking data with a single test body.

In the present invention, in the same temperature state as the test environment , both end portions of the test body are pressed against the test jig, and the test body is subjected to bending deformation so that the radius of curvature of the test body is different at each position on the surface . In this state, the strain distribution of the surface is obtained in advance from strain values at a plurality of positions on the surface of the test body, and then the test body is taken out after being immersed in a test environment for a predetermined time and cracked in the surface of the test body. The stress corrosion cracking data is obtained when the test occurs, and the test body to which the bending deformation is applied is again immersed in the test environment, taken out from the test environment after a predetermined time, and the surface of the test body is obtained. If new cracks have occurred, the stress corrosion cracking data is added and acquired.The stress corrosion cracking data is obtained when bending stress is applied to the specimen and tensile stress is applied. The trial And the immersion time in the test environment of the body, is to the distortion value at the crack occurrence position, characterized in that characterized in that the crack size is obtained by a set.

In addition, the present invention presses both ends of the test body against the test jig while the test body is immersed in the test environment, and the test body is bent and deformed so that the radius of curvature of the test body is different at each position on the surface. In this state, the strain is measured at a plurality of positions on the surface of the test body to obtain a strain distribution on the surface, and after the predetermined time has elapsed since the bending deformation is applied to the test body, the test body is Take out from the test environment, acquire stress corrosion cracking data when a crack occurs on the surface of the test body , and further immerse the test body to which the bending deformation is applied in the test environment for a predetermined time. If a new crack has occurred on the surface of the specimen after the test environment has been removed, the stress corrosion crack occurrence data is additionally acquired, and the stress corrosion crack occurrence data is bent on the specimen. Deformation Those wherein the immersion time in the given has been of the test body in the state where a tensile stress is given test environment, and the distortion value at the crack occurrence position, that the crack size is obtained by a set is there.

According to the present invention, both ends of the test specimen are pressed against the test jig, and the test specimen is subjected to bending deformation so that the radius of curvature of the test specimen is different at each position on the surface . Since the strain distribution of the surface is obtained from the strain values at a plurality of positions on the surface, the strain value at the crack generation position can be grasped even when a crack occurs at any position on the surface of the test body. In addition, by repeatedly immersing the specimen in the test environment for a predetermined time, a plurality of cracks can be generated in the specimen. From these facts, it is possible to obtain a plurality of stress corrosion crack occurrence data including a strain value at the crack occurrence position with an integrated test body without producing a large number of test bodies.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, the present invention is not limited to these embodiments.

[A] First embodiment (FIGS. 1 and 2)
FIG. 1 is a process diagram showing a first embodiment of a stress corrosion cracking test method according to the present invention. FIG. 2 is a flowchart showing the stress corrosion crack occurrence test method of FIG.

  In the stress corrosion crack occurrence test of the present embodiment, the test body 11 is immersed in the test environment 10A of the test apparatus 10 in a state where bending deformation is applied to the test body 11 and tensile stress is applied. This is a test for acquiring stress corrosion crack occurrence data related to stress corrosion cracks (cracks) generated on the surface of the body 11. The stress corrosion crack occurrence data includes a set of the immersion time of the test body 11 in the test environment 10A in a state where the tensile stress is applied to the test body 11, the strain value at the crack generation position, and the crack size. This is a data set.

  As shown in FIG. 1B, the test method for the stress corrosion cracking test is such that bending deformation is imparted to the flat plate-shaped test body 11 and tensile stress is applied in the same temperature state as the test environment 10A. In this state, strain is measured at a plurality of positions on the surface 12 of the test body 11, and the strain distribution of the surface 12 is obtained from the strain value. In the present embodiment, the test environment 10A is an atmosphere filled with a liquid at room temperature (for example, salt water) in which the test body 11 can be immersed. Further, the surface 12 of the test body 11 for which a strain distribution is required is a surface on the side where the stress becomes tensile due to bending deformation.

  Next, as shown in FIG. 1C, the test body 11 is immersed in the test environment 10 </ b> A of the test apparatus 10 for a predetermined time in a state where bending deformation is applied to the test body 11 and tensile stress is applied. After the predetermined time has elapsed, the test body 11 is taken out from the test environment 10A, and it is observed whether or not a stress corrosion crack (crack) has occurred on the surface 12 of the test body 11. Then, when the surface 12 of the test body 11 is cracked, stress corrosion crack occurrence data is acquired.

  The above test method will be described in more detail with reference to FIG.

  First, a plurality of strain gauges 13 are attached to the surface 12 of the test body 11 (S11). As described above, the surface 12 to which the strain gauge 13 is attached is a surface on the side where the stress becomes tensile when bending deformation is applied to the test body 11. As shown in FIG. 1A, the plurality of strain gauges 13 are affixed to almost the entire surface 12 of the test body 11 with almost no gap.

  Next, the test body 11 is fixed to the test jig 14, and bending deformation is applied (S12). As shown in FIG. 1B, the bending deformation is performed by pressing both ends of the test body 11 against the test jig 14 and fixing them with bolts 15 so that the radius of curvature of the test body 11 is different at each position on the surface 12. The test body 11 is bent and deformed. As a result, uneven distortion occurs on the surface 12 of the test body 11.

  Next, as shown in FIG. 1B, the surface of the test body 11 is subjected to bending deformation in the same temperature state as the test environment 10A, that is, in this embodiment, at room temperature. The strain generated at a plurality of 12 positions is measured by the strain gauge 13, and the strain distribution of the surface 12 is measured from the measured strain value (S13).

  After the strain measurement, the strain gauge 13 is removed from the surface 12 using an organic solvent or the like so as not to damage the surface 12 of the test body 11 (S14). In this state, as shown in FIG. 1C, the test body 11 in a state where bending deformation is applied by the test jig 14 and tensile stress is applied is immersed in the test environment 10A of the test apparatus 10 (S15). ).

  After the elapse of a predetermined time from this immersion, the test body 11 is taken out from the test environment 10A, and it is observed whether or not a crack is generated on the surface 12 of the test body 11 in a state where bending deformation is applied by the test jig 14 ( S16). When the occurrence of a crack is recognized, the immersion time of the test body 11 in the test environment 10A, the strain value measured in advance at the crack generation position, and the stress corrosion crack occurrence data with one set of crack dimensions are recorded. (S17). When a plurality of cracks are generated on the surface 12 of the test body 11, a plurality of sets of stress corrosion crack occurrence data are recorded.

  Furthermore, when the test body 11 to which this bending deformation is imparted is again immersed in the test environment 10A, the surface 12 of the test body 11 is observed after taking out from the test environment 10A after a predetermined time has elapsed, and a new crack has occurred. In addition, stress corrosion crack occurrence data is additionally acquired (S15 to S17). This procedure S15 to S17 is repeated once or a plurality of times to complete the test.

  According to the present embodiment, the following effect (1) is obtained.

  (1) In a state where bending deformation is applied to the test body 11, strain is measured by the strain gauges 13 at a plurality of positions on the surface 12 of the test body 11, and the strain distribution on the surface 12 of the test body 11 is calculated from the strain value. Since it is obtained in advance, the strain value at the crack occurrence position can be grasped even when a crack occurs at any position on the surface 12 of the test body 11. Moreover, a plurality of cracks can be generated in the test body 11 by repeatedly immersing the test body 11 in the test environment 10A for a predetermined time. From these facts, a plurality of pieces of stress corrosion crack occurrence data including strain values at the crack occurrence positions can be acquired by one test piece 11 without manufacturing a large number of test pieces 11. As a result, it is possible to efficiently maintain a database of stress corrosion crack occurrence data that is required in large numbers because of a large variation.

[B] Second embodiment (FIGS. 3 and 4)
FIG. 3 is a process diagram showing a second embodiment of the stress corrosion cracking test method according to the present invention. FIG. 4 is a flowchart showing the stress corrosion crack occurrence test method of FIG. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description will be simplified or omitted.

  This embodiment is different from the first embodiment in that a strain gauge 13 is attached to a surface 16 (FIG. 3A) opposite to the surface 12 of the test body 11.

  In other words, the strain gauge 13 is affixed to the substantially entire surface of the surface 16 on the side where the stress is compressed when bending deformation is applied to the test body 11 with almost no gap. The strain gauge 13 measures strain generated on the surface 16 side when bending deformation is applied to the test body 11. Then, the strain distribution of the surface 12 is obtained by setting the value obtained by inverting the sign of the measured value as the strain value generated on the surface 12 on the side where the stress is tensile in the test body 11.

  The stress corrosion crack occurrence test method of the present embodiment will be further described in detail with reference to FIG.

  First, the strain gauge 13 is affixed to almost the entire surface 16 on the side where the stress is compressed when bending deformation is applied to the test body 11 (S21). Next, steps S22 and S23 similar to the steps S12 and S13 of the first embodiment are performed, and as shown in FIG. 3B, the surface 16 of the test body 11 to which bending deformation is applied is formed. The strain value is measured by the strain gauge 13.

  Next, the sign of the strain value measured by the strain gauge 13 is reversed, and the strain value of the surface 12 on the side where the stress becomes tensile is obtained in the specimen 11 to which bending deformation is applied (S24). This is because the strain value of the surface 12 where the stress is tensile when the bending deformation is applied to the test body 11 is a neutral axis of the stress when the test body 11 is a thin plate (for example, a thickness of about 0.05 to 3 mm). This is because the sign of the strain value measured on the surface where the stress is compressed is inverted because the value is at the center of the thickness of the test body 11.

  Thereafter, as shown in FIG. 3C, the test body 11 to which bending deformation is applied is immersed in the test environment 10A without removing the strain gauge 13 from the test body 11 (S25). Then, steps S26 and S27 are executed in the same manner as steps S16 and S17 of the first embodiment, and stress corrosion crack occurrence data when a crack occurs on the surface 12 of the test body 11 is acquired. By repeating these steps S25, S26, and S27, a plurality of sets of stress corrosion crack occurrence data are acquired for one test body 11.

  Therefore, according to the present embodiment, in addition to the same effect as the effect (1) of the first embodiment, the following effect (2) is achieved.

  (2) When bending deformation is applied to the test body 11, the strain gauge 13 is stuck on the surface 16 on the compression side, not on the surface 12 on the side where the stress is tensile, so that the crack in the surface 12 Can be observed without removing the strain gauge 13. As a result, it is possible to omit the trouble of removing the strain gauge 13 from the test body 11 when the test body 11 to which bending deformation is imparted is immersed in the test environment 10A.

[C] Third embodiment (FIGS. 5 and 6)
FIG. 5 is a process diagram showing a third embodiment of the stress corrosion cracking test method according to the present invention. FIG. 6 is a flowchart showing the stress corrosion crack occurrence test method of FIG. In the third embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description will be simplified or omitted.

  This embodiment is different from the first embodiment in that the strain at a plurality of positions on the surface 12 of the specimen 11 to which bending deformation is applied is measured by a non-contact strain measurement method instead of the strain gauge 13. Is a point.

  That is, in the present embodiment, in the atmosphere at the same temperature as the test environment 10A, the test specimen 11 is subjected to bending stress using the test jig 14 and the bolt 15, and the stress is tensile in the test specimen 11. The strain at a plurality of positions of the surface 12 on the side to be measured is measured by a non-contact strain measurement method, and the strain distribution of the surface 12 is obtained from this strain value. Here, a typical non-contact strain measurement method is a moire method or a laser speckle method. Further, the test environment 10A in the present embodiment is an atmosphere filled with a liquid (for example, salt water) into which the test body 11 can be immersed, and the liquid temperature is a temperature other than room temperature, for example, a high temperature equal to or higher than room temperature. .

  The stress corrosion crack occurrence test method of the present embodiment will be further described in detail with reference to FIG.

  First, in the same atmosphere as the test environment 10A, as shown in FIG. 5 (A), before the bending deformation is applied to the test body 11, the stress is pulled when the bending deformation is applied. The surface state of the surface 12 is measured using, for example, the laser speckle strain measuring device 17 (S31). This laser speckle strain measuring device 17 is a strain measuring device to which a laser speckle method is applied. Instead of the laser speckle strain measuring device 17, a strain measuring device to which the moire method is applied may be used.

  Next, in the atmosphere at the same temperature as the test environment 10A, as shown in FIG. 5B, bending deformation is applied to the test body 11 using the test jig 14 and the bolt 15, and at this time, the stress is tensile. The surface state of the surface 12 on the side to be formed is measured using a laser speckle strain measuring device 17. Then, the strain of the surface 12 is measured from the change in the surface state of the surface 12 before and after applying the bending deformation to the test body 11, and the strain distribution of the surface 12 is obtained from the strain value (S32). Also in this case, instead of the laser speckle strain measuring device 17, a strain measuring device to which the moire method is applied may be used.

  Thereafter, the test body 11 to which bending deformation is applied is immersed in the test environment 10A as shown in FIG. 5C (S33). Then, procedures S34 and S35 are executed in the same manner as procedures S16 and S17 of the first embodiment, and stress corrosion crack occurrence data when a crack occurs on the surface 12 of the test body 11 is acquired. By repeating these steps S35, S36, and S37, a plurality of sets of stress corrosion crack occurrence data are acquired for one specimen 11.

  Therefore, according to this embodiment, in addition to the same effect as the effect (1) of the first embodiment, the following effects (3) and (4) are achieved.

  (3) In the test body 11 in the bent state, the strain on the surface 12 on which the stress becomes tensile is measured by a non-contact strain measuring method such as a moire method or a laser speckle method. Since the work of applying and removing the strain gauge 13 is not required, the work time can be saved.

  (4) Similarly, in the test body 11 in a bent state, the strain on the surface 12 on which the stress becomes tensile is measured by a non-contact strain measurement method such as a moire method or a laser speckle method. If the strain measuring apparatus to which the measurement method is applied is in a temperature range in which strain measurement can be performed, the strain measurement can be preferably performed even at room temperature.

[D] Fourth embodiment (FIGS. 7 and 8)
FIG. 7 is a process diagram showing the fourth embodiment of the stress corrosion cracking test method according to the present invention. FIG. 8 is a flowchart showing the stress corrosion crack occurrence test method of FIG. In the fourth embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description will be simplified or omitted.

  This embodiment differs from the first embodiment in that a simulated specimen 18 (FIG. 7A) configured with the same material and dimensions as the specimen 11 is used. The strain at the time of bending deformation is measured, and this measured value is regarded as a strain value in the test environment 10A of the test body 11.

  That is, in the simulated test body 18, a fine grid 20 is formed on the surface 19 on the side where the stress becomes tensile when bending deformation is applied. The strain on the surface 19 when bending deformation is applied to the simulation specimen 18 prepared in this way is measured from the amount of change of the grid 20 in the atmosphere at the same temperature as the test environment 10A. This measured value is regarded as the strain value of the surface 12 on the side where the stress is tensile of the test body 11 to which bending deformation is applied in the test environment 10A, and thereby the strain distribution of the surface 12 is obtained.

  Here, 10 A of test environments in this Embodiment are the atmosphere filled with the liquid (for example, salt water) which can immerse the test body 11, and the said liquid temperature is a temperature other than room temperature, for example, when it is high temperature above room temperature, for example. is there.

  The stress corrosion crack occurrence test method of the present embodiment will be further described in detail with reference to FIG.

  First, as shown in FIG. 7 (A), a fine grid 20 is formed on the surface 19 of the simulated test specimen 18 that is exactly the same as the test specimen 11, that is, the same material and dimensions as the test specimen 11. It is formed by baking (S41).

  Next, as shown in FIG. 7B, the simulated specimen 18 prepared in this way is exposed to the atmosphere at the same temperature as the test environment 10A, and the simulated specimen 18 before bending deformation is applied. The surface 19 is photographed by the camera 21, and the interval of the grid 20 is measured on the image by the photographic method or the laser measuring method to measure the initial value of the distortion (S42).

  Next, as shown in FIG. 7 (C), the simulated specimen 18 is exposed to the atmosphere at the same temperature as the test environment 10A, or is taken out from the atmosphere, and the simulated specimen 18 is placed in the test jig. Bending deformation is applied using 14 and the bolt 15 (S43). At this time, the bending deformation applied to the simulated specimen 18 is the same amount of bending deformation as the bending deformation applied to the specimen 11 before being immersed in the test environment 10A. Further, in the simulated specimen 18 to which this bending deformation is applied, the surface 19 is a surface on the side where the stress is tensile.

  Next, the simulated specimen 18 to which the bending deformation is applied is exposed to the atmosphere at the same temperature as the test environment 10A, and the surface 19 of the simulated specimen 18 is photographed using the camera 21, and is photographed or laser-measured. According to the method, the amount of change in the interval between the grids 20 is measured on the image, and the amount of change is converted into strain to measure the strain value. Then, the measured value is regarded as the strain value of the surface 12 on the tension side where the stress of the test body 11 to which bending deformation is applied in the test environment 10A (S44).

  Thereafter, as shown in FIG. 7D, the test body 11 is subjected to bending deformation using the test jig 14 and the bolt 15 and immersed in the test environment 10A (S45). Then, steps S46 and S47 are executed in the same manner as steps S16 and S17 of the first embodiment, and stress corrosion crack occurrence data when a crack occurs on the surface 12 of the test body 11 is acquired. By repeating these steps S45, S46 and S47, a plurality of sets of stress corrosion crack occurrence data are acquired for one test body 11.

  Therefore, according to this embodiment, in addition to the same effect as the effect (1) of the first embodiment, the following effect (5) is obtained.

  (5) A simulated specimen 18 made of the same material and dimensions as the specimen 11 is bent and deformed with the same bending amount as the specimen 11, and the specimen is simulated in the atmosphere at the same temperature as the test environment 10A. The strain generated on the surface 19 of 18 is measured by a photographic method or a laser measurement method, and this measured value is regarded as a strain value in the test environment 10A of the test body 11. From this, within the temperature range in which the above photographic method or laser method can be used, strain measurement of the surface 19 of the simulated specimen 18 can be performed even at room temperature, and consequently, the strain distribution of the surface 12 of the specimen 11 is measured. Can be obtained.

[E] Fifth embodiment (FIG. 9)
FIG. 9 is a flowchart showing a fifth embodiment of the stress corrosion cracking test method according to the present invention. In the fifth embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description will be simplified or omitted.

  This embodiment differs from the first embodiment in that the surface 12 on the side where the stress becomes tensile in the state where the test body 11 is subjected to bending deformation in the same temperature state as the test environment 10A. This is the point of obtaining the strain distribution of the surface 12 by calculating the strain at a plurality of positions from the analysis result obtained by numerical analysis such as the finite element method.

  Here, the test environment 10A in the present embodiment is an atmosphere filled with a liquid (for example, water) in which the test body 11 can be immersed, and the liquid temperature is room temperature or a temperature other than room temperature. .

  The stress corrosion crack occurrence test method of the present embodiment will be further described in detail with reference to FIG.

  First, in the same temperature state as the test environment 10A, the strain at a plurality of positions on the surface 12 on which the stress becomes tensile when bending deformation is applied to the test body 11 is calculated by numerical analysis such as a finite element method. Obtain (S51).

  Next, bending deformation is given to the test body 11 using the test jig 14 and the bolt 15 (S52). After this bending deformation, the test body 11 is immersed in the test environment 10A in a state where the bending deformation is applied (S53).

  Thereafter, steps S54 and S55 are executed in the same manner as steps S16 and S17 of the first embodiment, and stress corrosion crack occurrence data when a crack occurs on the surface 12 of the specimen 11 is acquired. By repeating these steps S53, S54, and S55, a plurality of sets of stress corrosion crack occurrence data are acquired for one specimen 11.

  Therefore, according to this embodiment, in addition to the same effect as the effect (1) of the first embodiment, the following effect (6) is achieved.

  (6) Since the strain value at the crack generation position is obtained from the analysis result of numerical analysis such as the finite element method, it is not necessary to actually measure the strain using the strain gauge 13 or the like, so the stress corrosion crack generation test is simplified. Can be implemented.

[F] Sixth embodiment (FIGS. 10 and 11)
FIG. 10 is a process diagram showing the sixth embodiment of the stress corrosion cracking test method according to the present invention. FIG. 11 is a flowchart showing the stress corrosion crack occurrence test method of FIG. In the sixth embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description will be simplified or omitted.

  The difference between the present embodiment and the first embodiment is that the test body 11 has strain at a plurality of positions on the surface 12 on the side where the stress becomes tensile when bending deformation is applied to the test body 11. It is a point which measures in the state immersed in the test environment 10A.

  That is, in the test method of the present embodiment, first, bending deformation is applied to the test body 11 in a state where the test body 11 is immersed in the test environment 10A. Next, in this state, in the test body 11, the strain on the surface 12 on the side where the stress is tensile is indirectly measured to obtain the strain distribution on the surface 12. Then, after a predetermined time has elapsed since the bending deformation is applied to the test body 11, the test body 11 is taken out from the test environment 10 </ b> A, and when a crack occurs on the surface 12 of the test body 11, stress corrosion crack occurrence data is acquired. To do.

  In the test body 11, the strain on the surface 12 on which the stress is tensile is indirectly measured using a strain gauge 22 attached to the surface 16 on the side where the stress is compressed. That is, the strain gauge 22 is affixed to almost the entire surface 16 of the test body 11 with almost no gap, and the strain generated when bending deformation is applied is measured by the strain gauge 22. Since the test body 11 is a thin plate and the central axis of the stress is the center of the thickness of the test body 11, the value obtained by inverting the sign of the measurement value of the strain gauge 22 is the value of the surface 12 on the side where the stress is tensile. It becomes possible to set it as a distortion value.

  Here, 10 A of test environments in this Embodiment are the atmosphere filled with the liquid (for example, salt water) which can immerse the test body 11, and the said liquid temperature is a temperature other than room temperature, for example, when it is high temperature above room temperature, for example. is there. The strain gauge 22 can be used at the same temperature as the test environment 10A, and is a high-temperature strain gauge, for example. A high temperature cable 23 is connected to each of the strain gauges 22 and the output of the strain gauges 22 is taken out.

  Unlike the test jig 14 and the bolt 15 of the first to fifth embodiments, what imparts bending deformation to the test body 11 in the present embodiment is a load device 24 equipped in the test apparatus 10. . The load device 24 includes a pair of support portions 25 that respectively support both end portions of the test body 11, and a press drive portion that presses the substantially central position in the longitudinal direction of the test body 11 that is supported at both end portions by the support portions 25. 26. When the pressing drive unit 26 presses the test body 11, bending deformation is imparted to the test body 11.

  The test method of the present embodiment will be further described in detail with reference to FIG.

  First, as shown in FIG. 10A, when bending deformation is applied to the test body 11, the strain gauge 22 is affixed to almost the entire surface 16 on the side where the stress is compressed (S61). . With the strain gauge 22 applied, the test body 11 is immersed in the test environment 10A as shown in FIG. 10B (S62). And before giving a bending deformation to the test body 11 with the load apparatus 24, when this test body 11 becomes the same temperature as the test environment 10A, the strain value of the surface 16 is measured by the strain gauge 22 as an initial value. (S63).

  Next, as shown in FIG. 10C, the test body 11 is pressed by the pressing drive unit 26 of the load device 24 in a state in which the test body 11 is immersed in the test environment 10 </ b> A, and bent to the test body 11. Deformation is given (S64). In this state, the strain on the surface 16 of the test body 11, that is, the surface 16 on the side where the stress is compressed is measured by the strain gauge 22 (S65).

  Then, the sign of the measurement value obtained by the strain gauge 22 is reversed, and the strain value of the surface 12 on the side where the stress is tensioned is obtained in the bent specimen 11 (S66).

  The test body 11 is taken out from the test environment 10A without removing the strain gauge 22 from the test body 11 after a lapse of a predetermined time from the time when the bending deformation is applied by the load device 24 while the test body 11 is immersed in the test environment 10A. The presence or absence of cracks is observed (S67). If cracking is observed, stress corrosion cracking is generated by setting the immersion time in the test environment 10A from the time when bending deformation is applied to the specimen 11, the strain value at the cracking position, and the crack size as one set. Data is recorded (S68).

  Thereafter, the procedures S62 and S64 to S68 are repeated once or a plurality of times to acquire a plurality of sets of stress corrosion crack occurrence data in one test body 11, and the test is terminated.

  Therefore, the present embodiment also has the same effect as the effect (1) of the first embodiment. In the present embodiment, the strain gauge 22 may be attached to the surface 12 on the side where the stress becomes tensile when bending deformation is applied to the test body 11. However, in this case, as in the first embodiment, it is necessary to remove the strain gauge 22 from the surface 12 of the test body 11 when observing a crack on the surface 12 of the test body 11.

FIGS. 3A to 3C are process diagrams showing a first embodiment of a stress corrosion cracking test method according to the present invention. The flowchart which shows the stress corrosion crack generation | occurrence | production test method of FIG. FIGS. 4A to 4C are process diagrams showing a second embodiment of the stress corrosion cracking test method according to the present invention. Flowchart showing the stress corrosion cracking occurrence test method of FIG. FIGS. 4A to 4C are process diagrams showing a third embodiment of the stress corrosion cracking test method according to the present invention. 6 is a flowchart showing a stress corrosion crack occurrence test method in FIG. 5. FIGS. 4A to 4D are process diagrams showing a fourth embodiment of the stress corrosion cracking test method according to the present invention. The flowchart which shows the stress corrosion crack generation | occurrence | production test method of FIG. The flowchart which shows 5th Embodiment of the stress corrosion crack generation | occurrence | production test method which concerns on this invention. FIGS. 9A to 9C are process diagrams showing a sixth embodiment of the stress corrosion cracking occurrence test method according to the present invention. 11 is a flowchart showing a stress corrosion crack occurrence test method of FIG. The side view which shows the conventional stress corrosion crack occurrence test method. The side view which shows the other conventional stress corrosion crack generation | occurrence | production test method.

Explanation of symbols

10A Test environment 11 Specimen 12 Surface 13 Strain gauge 16 Surface 17 Laser speckle strain measuring device 18 Simulated specimen 19 Surface 20 Grid 21 Camera 22 Strain gauge

Claims (10)

In the same temperature state as the test environment , both ends of the test body are pressed against the test jig, and the test body is subjected to bending deformation so that the radius of curvature of the test body is different at each position on the surface. Obtain the strain distribution of the surface in advance from the strain values at multiple positions on the surface of the specimen,
Next, the test specimen is taken out after being immersed in a test environment for a predetermined time,
Acquire stress corrosion cracking data when a crack occurs on the surface of the specimen ,
Further, the test body to which this bending deformation is applied is immersed again in the test environment, and when a predetermined crack has occurred on the surface of the test body after taking out from the test environment after a predetermined time has passed, Acquire additional corrosion cracking data,
This stress corrosion cracking data includes the time of immersion of the specimen in the test environment with the bending stress applied to the specimen, the strain value at the crack occurrence position, and the crack size. Stress corrosion crack occurrence test method characterized by being a set . The strain distribution on the surface of the test specimen is determined by applying a plurality of strain gauges to the surface on which the stress becomes tensile when a bending deformation is applied to the test specimen. Obtained by measuring,
The stress corrosion cracking occurrence test method according to claim 1, wherein the strain gauge is removed from the test body before the test body is immersed in a test environment. The strain distribution on the surface of the test specimen is determined by applying a plurality of strain gauges to the surface on which stress is compressed when bending deformation is applied to the test specimen, and the strain generated when the bending deformation is applied by the strain gauge. The stress corrosion crack occurrence test method according to claim 1, wherein the stress corrosion crack occurrence test method according to claim 1, wherein the stress corrosion crack occurrence test method is obtained by measuring and reversing the sign of the measured value as a strain value of a surface where stress becomes tensile. The strain distribution on the surface of the test specimen is measured by the non-contact strain measurement method in the atmosphere at the same temperature as the test environment, with the test specimen being subjected to bending deformation, at multiple positions on the surface of the test specimen. The stress corrosion cracking occurrence test method according to claim 1, wherein the stress corrosion crack occurrence test method is obtained. The stress corrosion crack occurrence test method according to claim 4 , wherein the non-contact strain measurement method is a laser speckle method or a moire method. The strain distribution on the surface of the specimen is composed of the same material and dimensions as the specimen, and a simulated specimen having a grid formed on the surface is prepared. The distortion of the surface of the simulated specimen when deformation is applied is measured by the amount of change in the grid interval in the atmosphere at the same temperature as the test environment, and this measured value is the strain value in the test environment of the specimen. The stress corrosion cracking occurrence test method according to claim 1, wherein the stress corrosion crack occurrence test method is obtained by regarding The stress corrosion cracking occurrence test method according to claim 1, wherein the strain distribution on the surface of the test body is obtained from an analysis result obtained by numerical analysis such as a finite element method. In a state where the test body is immersed in the test environment, both end portions of the test body are pressed against the test jig , and bending deformation is applied to the test body so that the radius of curvature of the test body is different at each position on the surface .
In this state, strain is measured at a plurality of positions on the surface of the test body to obtain a strain distribution on the surface,
After a predetermined time has elapsed since the bending deformation of the test body, the test body is taken out from the test environment,
Acquire stress corrosion cracking data when a crack occurs on the surface of the specimen ,
Further, the test body to which this bending deformation is applied is immersed again in the test environment, and when a predetermined crack has occurred on the surface of the test body after taking out from the test environment after a predetermined time has passed, Acquire additional corrosion cracking data,
This stress corrosion cracking data includes the time of immersion of the specimen in the test environment with the bending stress applied to the specimen, the strain value at the crack occurrence position, and the crack size. Stress corrosion crack occurrence test method characterized by being a set . Strain distribution of the surface of the specimen, according to claim 8, wherein obtaining the strain value measured is plural affixed to the surface of the specimen, the strain gauges can be used in the test environment the same temperature Stress corrosion cracking test method. The strain distribution on the surface of the test specimen is determined by applying a plurality of strain gauges to the surface on which stress is compressed when bending deformation is applied to the test specimen, and the strain generated when the bending deformation is applied by the strain gauge. The stress corrosion cracking occurrence test method according to claim 8 or 9 , wherein the stress corrosion crack occurrence test method according to claim 8 or 9 , wherein a value obtained by measuring and reversing the sign of the measured value is obtained as a strain value of a surface where the stress becomes tensile.

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