JP4830907B2 - Stress corrosion cracking test specimen manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a test body in which a crack simulating stress corrosion cracking is applied to a welded portion.

  In nuclear power plants, etc., nondestructive inspection such as ultrasonic flaw inspection is performed on each part of various equipment, but it is said that it is particularly difficult to detect defects in welded parts, and the accuracy of nondestructive inspection technology is improved. It is necessary to plan. In order to improve the accuracy of non-destructive inspection technology, non-destructive inspection is performed to detect SCC using a test specimen in which SCC (stress corrosion cracking) is artificially applied to the weld. It is necessary to study about.

  When applying the SCC to the welded part of the specimen, it is necessary to generate a predetermined tensile stress at the site where the SCC is applied in the welded part. Conventionally, in the case of a plate-like or tubular specimen, the specimen is immersed in a solution in a state where tensile stress is generated at a site to which SCC is applied by bending the specimen (three-point bending or four-point bending). By doing so, SCC was provided to the weld of the specimen. Such a method for producing a stress corrosion cracking test specimen is also described in Patent Documents 1 and 2 and the like.

JP 2005-61914 A JP 2006-118862 A

  In the conventional method, it was effective for a specimen having a uniform thickness, but for a specimen having a complex shape with a non-uniform thickness, stress concentration was generated at a desired site. It was difficult to give SCC to the site.

  Although cited document 1 describes a method of applying SCC to a test specimen having a non-uniform thickness (see paragraphs 0032 to 0041 of cited document 1, FIG. 3 and the like), this method uses an actuator. Since the load is applied to the test body, the configuration is complicated, and it is difficult to apply to a small test body.

  Accordingly, an object of the present invention is to provide a method for producing a stress corrosion cracking test specimen that can impart a crack simulating stress corrosion cracking to a desired site in a test specimen having a non-uniform thickness and a complex shape. There is.

In order to achieve the above object, the present invention provides a method of manufacturing a test body in which a crack simulating stress corrosion cracking is imparted to a welded portion, and a pair of the test body is provided so as to sandwich a portion where the crack of the welded portion is imparted. The columnar member is attached, and a bolt is screwed into the free end portion of one of the pair of columnar members and the tip of the bolt is brought into contact with the free end portion of the other columnar member. Then, by tightening the bolt, separating the parts on the free end side of the pair of columnar members and generating a tensile stress at the site where the crack of the weld is applied, the crack is applied to the site, and then In this method, the pair of columnar members are removed from the test body, and a plate-like member is bridged between the pair of columnar members, and the space surrounded by the pair of columnar members and the plate-like member is provided. Put the solution By, when tightening the bolt, it is obtained so as to hold the weld corrosive environment.

Here, a transparent acrylic plate may be used as the plate member .

  According to the present invention, there is an excellent effect that a crack simulating a stress corrosion crack can be imparted to a desired site in a complex-shaped specimen having a non-uniform thickness.

  Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a front view of a test body for explaining a method for producing a stress corrosion cracking test specimen according to an embodiment of the present invention. 2 is a view taken along the line II-II in FIG.

  As shown in FIGS. 1 and 2, the test body 10 connects the base material 11, the base material 12 having a thickness larger than that of the base material 11 and abutted against the base material 11, and the base materials 11 and 12. And a welded portion (butt welded portion) 13 formed on the surface. The base materials 11 and 12 and the welded portion 13 are made of a material (for example, a nickel-based alloy) having SCC (Stress Corrosion Cracking) sensitivity. The test body 10 of the present embodiment is obtained by dividing the shape of the control rod guide tube installed at the bottom of the reactor pressure vessel into four in the circumferential direction.

  A method for producing a stress corrosion cracking test specimen according to this embodiment will be described.

  First, the build-up welding seat 14 is formed by welding so as to cover a portion A (see FIGS. 1 and 2) to which a crack (a crack simulating SCC) in the welded portion 13 of the test body 10 is applied. The overlay welding seat 14 is made of a material (for example, a nickel-based alloy) having SCC sensitivity. Next, the groove 15 is formed by cutting out the center portion of the overlay welding seat 14 by machining or the like. In the present embodiment, the bottom surface of the groove 15 is above the surface of the welded portion 13, but the bottom surface of the groove 15 and the surface of the welded portion 13 may be matched.

  Next, a pair of columnar members 16 and 17 are welded to the build-up weld seat 14 formed on the test body 10 so as to sandwich the groove 15 of the build-up weld seat 14, that is, the portion A that gives the crack of the welded portion 13. Install. As a result, the columnar member / building weld weld 18 is formed between the columnar members 16 and 17 and the overlay welding seat 14.

  Here, the columnar members 16 and 17 are for generating a tensile stress in the width direction of the test body 10 at a site A where the crack of the welded portion 13 is imparted. Without these columnar members 16, 17, it is difficult to generate a tensile stress in the width direction of the test body 10 at the site A where the welded portion 13 is cracked.

  Next, the part A which gives the crack of the welded part 13 is kept in a corrosive environment. In the present embodiment, the solution A is immersed (applied) in a site A that gives a crack in the welded portion 13 so that the site A that gives a crack in the welded portion 13 is kept in a corrosive environment. Specifically, in the present embodiment, a plate-like member 20 is bridged between a pair of columnar members 16, 17, and a space surrounded by the pair of columnar members 16, 17 and the plate-like member 20 (of the build-up welding seat 14. The solution 19 is placed in the groove 15). As the solution 19, for example, a potassium tetrathionate solution can be used. As the plate-like member 20, for example, a member made of a transparent material such as an acrylic plate can be used, and by doing so, it becomes easy to observe the occurrence and progress of cracks. Further, a sealing member (not shown) made of silicon or the like may be interposed between the columnar members 16 and 17 and the plate-like member 20 for sealing.

  Next, the bolt hole 21 provided in the portion on the free end side of one columnar member 16 out of the pair of columnar members 16 and 17 in a state where the portion A to which the crack of the welded portion 13 is given is held in a corrosive environment. The bolt 22 is screwed and the tip of the bolt 22 is brought into contact with the free end portion of the other columnar member 17. In this state, the bolts 22 are tightened to separate the portions on the free end side of the pair of columnar members 16 and 17. At this time, the tensile stress P (refer FIG. 1) generate | occur | produces in the site | part A which provides the bottom part of the groove | channel 15 of the overlay welding seat 14, and the crack of the welding part 13. FIG.

  When tensile stress P is generated in the bottom portion of the groove 15 of the build-up welding seat 14 and the portion A that gives cracks in the welded portion 13 in a state where the portion A that gives cracks in the welded portion 13 is maintained in a corrosive environment, A crack is generated in the bottom surface of the groove 15 of the prime welding seat 14, and the crack progresses toward the welded portion 13 below the bottom surface of the groove 15. Then, the solution 19 enters the crack.

  The determination as to whether or not a crack has occurred in the part A to which the crack of the welded part 13 is given is, for example, by measuring the potential across the part A to which the crack of the welded part 13 is given and based on the change (decrease) in the potential. Do.

  And if the crack was provided to the site | part A which gives the crack of the welding part 13 by tensile stress, as shown in FIG. 3, while removing the columnar members 16 and 17 from the test body 10, and overlay welding seat 14 grade | etc., Remove. If it does so, only the front-end | tip part of the crack formed in the welding part 13 will remain. Since the tip of the crack is minute and is a simulated SCC, the specimen 10 can be used for research on nondestructive inspection for detecting SCC.

  According to the present embodiment, the pair of columnar members 16 and 17 are attached so as to sandwich the portion A that gives the crack of the welded portion 13 to the test body 10, and one columnar member 16 of the pair of columnar members 16 and 17 is attached. The bolt 22 is screwed into the free end portion of the first member, the tip of the bolt 22 is brought into contact with the free end portion of the other columnar member 17, the bolt 22 is tightened, and the pair of columnar members 16, 17 are free. Since the end portions are separated from each other and a tensile stress is generated in the portion A that gives the crack of the welded portion 13, the portion A is cracked. Even if it is the test body 10, by attaching the columnar members 16 and 17 so as to sandwich the part A to be cracked, stress concentration is generated in a desired part, and a crack simulating SCC is given to the part. OK To become.

  In addition, since an actuator or the like is not required and the configuration is compact, it can be easily applied to a small specimen. Therefore, in order to accelerate the corrosion of the welded portion 13, it is possible to pressurize the test body 10 using an autoclave (pressure kettle).

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, It is possible to take other various embodiment.

  For example, the test body 10 may be plate-shaped or tubular.

It is a front view of the test body for demonstrating the stress corrosion cracking provision test body manufacturing method which concerns on one Embodiment of this invention. It is the II-II arrow directional view of FIG. It is side sectional drawing of a test body, and shows the state which removed the columnar member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Test body 13 Welding part 16 Columnar member 17 Columnar member 22 Bolt

Claims (2)

In a method of manufacturing a test body in which a crack simulating stress corrosion cracking is applied to a weld,
A pair of columnar members are attached to the test body so as to sandwich the portion where the crack of the welded portion is sandwiched, and a bolt is screwed into a portion of one of the pair of columnar members on the free end side, and the bolt Of the other columnar member is brought into contact with the portion on the free end side, the bolt is tightened, and the portions on the free end side of the pair of columnar members are separated from each other to pull the welded portion to a crack. By generating stress, it is a method of giving a crack to the part, and then removing the pair of columnar members from the test body ,
A plate-like member is bridged between the pair of columnar members, and a solution is put into a space surrounded by the pair of columnar members and the plate-like member, so that when the bolt is tightened, the welded portion is corrosive environment. A method for producing a stress corrosion cracking test specimen, wherein The method for producing a stress corrosion cracking test specimen according to claim 1, wherein a transparent acrylic plate is used as the plate-like member .

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