CN115046915A - Heat transfer pipe indentation preparation device and indentation induced stress corrosion cracking test method - Google Patents

Abstract

The invention discloses a heat transfer pipe dent preparation device and a test method, wherein the heat transfer pipe dent preparation device comprises: a base; the bracket is arranged on the base; the upper end of the swing rod is rotatably connected to the bracket, so that the swing rod can swing relative to the bracket; the positioning fixture is arranged on the base and positioned on a swinging path of the swinging rod, and is used for clamping a heat transfer pipe sample with a C-shaped cross section; the punch comprises a counterweight part and a punch body, the counterweight part is detachably connected to the lower end of the swing rod, and the punch body is arranged on one side, facing the positioning fixture, of the counterweight part. The heat transfer pipe indentation preparation device can process indentations with different depths and shapes on the outer surface of a heat transfer pipe sample, so that related experiments can be conducted to research the stress corrosion cracking mechanism of the heat transfer pipe with the indentations under the coupling of a plurality of variable factors.

Description

Heat transfer tube dent preparation device and test method for dent-induced stress corrosion cracking

technical field

The invention relates to the technical field of nuclear power, in particular to a device for preparing dents of a heat transfer tube and a test method for stress corrosion cracking caused by dents.

Background technique

In the prior art, the heat transfer tube of the steam generator is used as the heat exchange hub for the primary water and the secondary water in the PWR nuclear power plant. Specifically, the inner side of the heat transfer tube is the primary water, and the outer side of the heat transfer tube is the secondary circuit. Water makes its service environment harsh and complex, so the heat transfer tube is a sensitive part prone to stress corrosion cracking.

The on-site investigation found that after a certain period of service of the heat transfer tube, there will be many dents with different depths and shapes on the outer surface. Therefore, it is speculated that the above-mentioned dents may cause stress corrosion cracking of the heat transfer tubes in the secondary circuit water environment. Since the actual damage of the heat transfer tube cannot be detected by the existing detection technology during the service period, and the influence of the above-mentioned dents on the service life of the heat transfer tube cannot be theoretically evaluated, it is necessary to simulate the heat transfer tube through experiments. The dents formed by the impact on the outer surface of the heat transfer tubes are used to study the influence of the above dents on the service life of the heat transfer tubes. Factors such as temperature, medium concentration, pH value and the stress on the heat transfer tube will also affect the service life of the heat transfer tube, so it is necessary to couple the stress of the dented heat transfer tube under the coupling of multiple variable factors. The corrosion cracking mechanism is studied, so as to more accurately evaluate the influence of the above dents on the service life of heat transfer tubes, and then provide a theoretical basis for seeking effective means to improve the service life of heat transfer tubes.

SUMMARY OF THE INVENTION

The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a heat transfer tube dent preparation device, which can process dents with different depths and shapes on the outer surface of the heat transfer tube sample, so as to facilitate relevant experiments to study multiple variable factors Stress corrosion cracking mechanism of dented heat transfer tubes under coupling.

The present invention also provides a test method for dent-induced stress corrosion cracking based on the above-mentioned heat transfer tube dent preparation device.

According to the first aspect of the present invention, the device for preparing dents for heat transfer tubes includes: a base; a bracket, the bracket is arranged on the base; and a swing rod, the upper end of the swing rod is rotatably connected to the a bracket, so that the pendulum rod can swing relative to the bracket; a positioning fixture, the positioning fixture is arranged on the base and located on the swing path of the pendulum rod, and the positioning fixture is used for clamping the cross-section of the C-type heat transfer tube sample; punch, the punch includes a weight part and a punch main body, the weight part is detachably connected to the lower end of the swing rod, and the punch main body is arranged on the The weight portion faces one side of the positioning fixture.

The device for preparing a heat transfer tube dent according to an embodiment of the present invention has at least the following beneficial effects: when in use, the heat transfer tube sample is first clamped on the positioning fixture, and then an external force is applied to drive the pendulum rod relative to the The bracket swings, so that the punch is far away from the heat transfer tube sample, and then the applied external force is removed, so that the punch drives the swing rod to swing relative to the bracket under the action of the gravity of the counterweight, thereby The punch body is made to strike the outer surface of the heat transfer tube sample and dents are machined on the outer surface of the heat transfer tube sample, wherein the position of the punch can be adjusted to remove the applied external force. The height of the dent can be adjusted to adjust the depth of the processed dent, and at the same time, the punch with different shapes of the punch body can be replaced to process the dent of different shapes, so that the above-mentioned heat transfer tube dent preparation device can The outer surface of the sample is machined with dents of different depths and shapes, so that relevant experiments can be carried out to study the stress corrosion cracking mechanism of heat transfer tubes with dents under the coupling of multiple variables.

According to some embodiments of the present invention, the punch is connected to the swing rod through a bolt and a nut, the lower end of the swing rod is provided with a connecting portion, and the connecting portion is provided with a first hole for passing the bolt. An installation hole, the top of the counterweight portion is provided with an installation slot for embedding the connecting portion, and the counterweight portion corresponding to the first installation hole is provided with a counterweight portion for passing through the counterweight portion. the second installation hole of the bolt, the connecting part is embedded in the installation groove, the bolt is penetrated in the first installation hole and the second installation hole, and the nut is threadedly connected to the the shank of the bolt so that the weight is sandwiched between the nut and the head of the bolt.

According to some embodiments of the present invention, two punch main bodies are disposed on the counterweight portion, and the two punch main bodies are respectively disposed on opposite sides of the counterweight portion.

According to some embodiments of the present invention, a dial is fixedly arranged on the bracket corresponding to the pendulum rod.

According to some embodiments of the present invention, the swing rod is detachably connected to the bracket, an adjustment structure is provided between the swing rod and the bracket, and the adjustment structure can adjust the punch to be in a free hanging state height at time.

According to some embodiments of the present invention, the adjustment structure includes a connecting shaft rotatably disposed on the bracket, the connecting shaft is provided with a third mounting hole for penetrating the swing rod, the swing rod The upper end of the connecting shaft passes through the third installation hole, the connecting shaft is provided with a fourth installation hole that communicates with the third installation hole, the fourth installation hole is a threaded hole, and the fourth installation hole The inner thread is connected with a jack screw whose end part is abutted against the swing rod.

According to some embodiments of the present invention, the diameter of the lower part of the pendulum rod is larger than the diameter of the upper part of the pendulum rod, and the lower part of the pendulum rod is provided with an external thread structure, so that the lower part of the pendulum rod can be installed with a threaded hole External counterweight.

According to some embodiments of the present invention, the positioning fixture includes a positioning pin and a rod-shaped positioning body, and a side of the positioning body facing the counterweight portion is provided with an inner surface for fitting the heat transfer tube sample. An arc-shaped portion is provided with a positioning pin hole for inserting the positioning pin.

The test method for dent-induced stress corrosion cracking according to the embodiment of the second aspect of the present invention, which is based on the device for preparing a dent of a heat transfer tube according to the embodiment of the first aspect of the present invention, includes the following steps: preparing a heat transfer tube sample , using the heat transfer tube of the steam generator to prepare a heat transfer tube sample with a C-shaped cross section; impact dents, using the above-mentioned heat transfer tube dent preparation device to impact dents on the outer surface of the heat transfer tube sample; Apply stress to the heat transfer tube sample, use a stress corrosion fixture to clamp the heat transfer tube sample and apply a preset stress to the heat transfer tube sample; put the heat transfer tube sample into the reactor, and pour it into the reactor at the same time. Enter the pre-configured solution for simulating the service environment of the heat transfer tube; set the temperature, pressure, flow rate and other parameters in the reaction kettle; after a preset time, take out the heat transfer tube sample for observation.

The test method for dent-induced stress corrosion cracking according to the embodiment of the present invention has at least the following beneficial effects: during the experiment, multiple groups of control experimental groups can be set, wherein the variables of each group are the depth of the dent and the shape of the dent respectively. , the stress of the heat transfer tube sample, the pH value of the solution, the concentration of the solution, the temperature in the reactor, the pressure in the reactor, the flow rate in the reactor and other parameters, so that the coupling of multiple variables can be studied. Stress corrosion cracking mechanism for pitted heat transfer tubes.

According to some embodiments of the present invention, the stress corrosion fixture includes a screw rod, a limit nut, an adjustment nut and a compression spring, the screw rod is used to pass through the heat transfer tube sample, and the limit nut is threadedly connected to the One end of the screw is used to limit the heat transfer tube sample, the adjusting nut is threadedly connected to the other end of the screw, the compression spring is sleeved on the screw, and one end of the compression spring abuts On the adjusting nut, the other end of the compression spring is used to press the heat transfer tube sample.

Additional aspects and advantages of the present invention will be set forth, in part, from the following description, and in part will be apparent from the following description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of embodiments taken in conjunction with the accompanying drawings, wherein:

1 is a schematic structural diagram of a heat transfer tube dent preparation device according to an embodiment of the present invention;

2 is a schematic structural diagram of a pendulum rod according to an embodiment of the present invention;

3 is a schematic top view of a punch according to an embodiment of the present invention;

Fig. 4 is the assembly schematic diagram of the pendulum rod, the punch and the connecting shaft according to the embodiment of the present invention;

5 is a schematic partial cross-sectional view of the structure shown in FIG. 4 from another perspective;

6 is a schematic structural diagram of a positioning fixture according to an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a stress corrosion jig according to an embodiment of the present invention after clamping a heat transfer tube sample.

Reference number:

Heat transfer tube sample a, base 100, bracket 200, swing rod 300, connecting portion 310, first mounting hole 311, abutting surface 320, positioning fixture 400, positioning body 410, arc portion 420, positioning pin hole 430, Punch 500, counterweight 510, mounting groove 511, second mounting hole 512, punch body 520, dial 600, connecting shaft 700, third mounting hole 710, fourth mounting hole 720, pointer 800, stress corrosion jig 900, screw 910, limit nut 920, adjustment nut 930, compression spring 940, washer 950.

Detailed ways

The following describes in detail the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary, only used to explain the present invention, and should not be construed as a limitation of the present invention.

In the description of the present invention, it should be understood that if the orientation description is involved, for example, the orientation or positional relationship indicated by up, down, front, rear, left, right, etc. is based on the orientation or positional relationship shown in the drawings, only It is to facilitate the description of the present invention and to simplify the description, rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention.

In the description of the present invention, if there are words such as several, greater than, less than, more than, above, below, within, etc., where the meaning of several is one or more, the meaning of multiple is two or more, greater than, less than, more than etc. shall be understood as not including this number, and above, below, within, etc., shall be understood as including this number.

In the description of the present invention, if words such as first and second appear, they are only used for the purpose of distinguishing technical features, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicit Indicates the order of the indicated technical features.

In the description of the present invention, unless otherwise clearly defined, words such as setting, installation, connection should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

Referring to FIG. 1 , an apparatus for preparing a heat transfer tube dent according to an embodiment of the present invention includes a base 100 , a bracket 200 , a swing rod 300 , a positioning fixture 400 and a punch 500 .

The bracket 200 is disposed on the base 100, and the upper end of the swing rod 300 is rotatably connected to the bracket 200, so that the swing rod 300 can swing relative to the bracket 200, the positioning fixture 400 is disposed on the base 100 and is located on the swing path of the swing rod 300, The positioning fixture 400 is used for clamping the heat transfer tube sample a with a C-shaped cross section. The punch 500 includes a counterweight portion 510 and a punch body 520. The counterweight portion 510 is detachably connected to the lower end of the pendulum rod 300. The head body 520 is disposed on the side of the weight portion 510 facing the positioning fixture 400 .

When in use, the heat transfer tube sample a is first clamped on the positioning fixture 400, and then an external force is applied to drive the pendulum rod 300 to swing relative to the bracket 200, so that the punch 500 is far away from the heat transfer tube sample a, and then the applied external force is removed. , so that the punch 500 drives the pendulum rod 300 to swing relative to the bracket 200 under the gravity of the counterweight portion 510, so that the punch body 520 hits the outer surface of the heat transfer tube sample a and hits the outer surface of the heat transfer tube sample a. A dent is processed on the outer surface, wherein the depth of the processed dent can be adjusted by adjusting the height of the punch 500 when the applied external force is removed (that is, adjusting the swing angle of the pendulum rod 300 ), and at the same time, it can be replaced The punch 500 with the punch body 520 of different shapes is used to process dents of different shapes, so that the above-mentioned heat transfer tube dent preparation device can process the outer surface of the heat transfer tube sample a with different depths and different shapes. dents in order to conduct relevant experiments to study the stress corrosion cracking mechanism of dented heat transfer tubes under the coupling of multiple variable factors.

1 to 3 , in some of the embodiments, the punch 500 is connected to the swing rod 300 through a bolt (not shown in the figure) and a nut (not shown in the figure), and the lower end of the swing rod 300 is provided with a connection part 310, the connecting part 310 is provided with a first mounting hole 311 for piercing the bolt, the top of the counterweight part 510 is provided with a mounting groove 511 for embedding the connection part 310, and the counterweight part 510 corresponds to the first mounting hole 311 A second mounting hole 512 is provided which penetrates through the counterweight portion 510 and is used to pass through the bolt. The connecting portion 310 is embedded in the mounting groove 511, and the bolt is passed through the first mounting hole 311 and the second mounting hole 512. The nut thread Connected to the shank of the bolt so that the counterweight 510 is sandwiched between the nut and the head of the bolt, the structure is simple and easy to install and remove the punch 500 . Specifically, the shape of the punch body 520 includes hemispherical and pyramidal shapes. Of course, the shape of the punch body 520 may also include other shapes, which are not limited here. In addition, the material used for the punch body 520 is tool steel, high-speed steel , Die steel, carbide steel and other high-hard wear-resistant materials.

Referring to FIGS. 1 , 3 and 5 , in some embodiments, two punch bodies 520 are provided on the counterweight portion 510 , and the two punch bodies 520 are respectively disposed on opposite sides of the counterweight portion 510 , During assembly, the restriction of the installation direction can be reduced, which is beneficial to improve the assembly efficiency. At the same time, the two punch bodies 520 can be set to different shapes, so that the same punch 500 can process dents of two different shapes.

Referring to FIG. 1 , in some of the embodiments, a dial 600 is fixedly provided on the bracket 200 corresponding to the swing rod 300 , so as to adjust the depth of the processed indentation through the swinging angle of the swing rod 300 .

It should be noted that, in some of the embodiments, the swing rod 300 is detachably connected to the bracket 200, and an adjustment structure is provided between the swing rod 300 and the bracket 200, and the adjustment structure can adjust when the punch 500 is in a free hanging state ( That is, the height of the pendulum rod 300 in a vertical state), so as to meet different test requirements.

Referring to FIGS. 1 , 4 and 5 , in some of the embodiments, the adjustment structure includes a connecting shaft 700 rotatably disposed on the bracket 200 , and the connecting shaft 700 is provided with a third installation for passing through the swing rod 300 Hole 710, the upper end of the pendulum rod 300 is penetrated in the third installation hole 710, the connecting shaft 700 is provided with a fourth installation hole 720 communicated with the third installation hole 710, the fourth installation hole 720 is a threaded hole, and the fourth installation hole 720 is a threaded hole. The hole 720 is threadedly connected with a top wire (not shown in the figure) whose end abuts on the pendulum rod 300. When it is necessary to adjust the height of the punch 500 in a suspended state, loosen the top wire to make the end of the top wire Separated from the swing rod 300, the swing rod 300 can be driven to adjust the length of the swing rod 300 passing through the third mounting hole 710, so as to adjust the height of the punch 500 when it is in a suspended state, and after the adjustment is completed, tighten the top wire to make the top wire It is only necessary to abut the end of the pendulum rod 300 and restrict the movement of the pendulum rod 300 relative to the connecting shaft 700. The structure is simple and easy to implement. Correspondingly, the dial 600 is provided with an escape hole through which the connecting shaft 700 can pass. , wherein, one end of the connecting shaft 700 away from the bracket 200 is fixedly provided with a pointer 800 linked with the connecting shaft 700 corresponding to the dial 600 , so as to observe the swinging angle of the pendulum rod 300 .

2, 4 and 5, in some of the embodiments, the upper part of the pendulum rod 300 is provided with a planar abutment surface 320 corresponding to the end of the top wire, which is beneficial to increase the distance between the end of the top wire and the top wire. The contact area of the pendulum rod 300 enables the top wire to more stably restrict the movement of the pendulum rod 300 relative to the connecting shaft 700 .

It should be noted that, in some other embodiments, the swing rod is provided with a waist-shaped hole arranged along its length direction, the connecting shaft is fixedly arranged on the bracket, the connecting shaft passes through the waist-shaped hole, and the swing rod is provided with There is a threaded hole communicated with the waist-shaped hole, and the threaded hole is threadedly connected with a jack screw whose end is abutted against the connecting shaft, which is not limited here.

4 and 5, in some embodiments, the diameter of the lower part of the swing rod 300 is larger than the diameter of the upper part of the swing rod 300, and the lower part of the swing rod 300 is provided with an external thread structure, so that the lower part of the swing rod 300 can be installed with The external counterweight of the threaded hole can adjust the counterweight at the lower part of the pendulum rod 300. When the depth of the dent to be processed is deep, only adjusting the swing angle of the pendulum rod 300 can no longer meet the processing requirements. The manner of adjusting the counterweight at the lower part of the pendulum rod 300 assists in adjusting the depth of the machined dent.

Referring to FIG. 6 , in some of the embodiments, the positioning fixture 400 includes a positioning pin (not shown in the figure) and a rod-shaped positioning body 410 . The arc portion 420 on the inner surface of the heat transfer tube sample a is provided with a positioning pin hole 430 for inserting the positioning pin on the arc portion 420, wherein the heat transfer tube sample a is provided with a positioning pin for passing through it. When clamping the heat transfer tube sample a, first make the inner surface of the heat transfer tube sample a fit on the arc-shaped part 420, and then pass the positioning pins on the heat transfer tube sample a for piercing It is enough to set the through hole of the positioning pin and insert the positioning pin into the positioning pin hole 430. The structure is simple and easy to implement. Of course, the above-mentioned positioning pin can also be replaced with a screw. Correspondingly, the positioning pin hole is replaced by a screw. It may be a threaded hole, which is not limited here.

The test method for dent-induced stress corrosion cracking according to an embodiment of the present invention is based on the above-mentioned heat transfer tube dent preparation device, and includes the following steps: preparing a heat transfer tube sample a, using a heat transfer tube of a steam generator to prepare Heat transfer tube sample a with a C-shaped cross section; impact dents, use the above-mentioned heat transfer tube dent preparation device to impact dents on the outer surface of heat transfer tube sample a; apply stress to heat transfer tube sample a , use the stress corrosion fixture 900 to clamp the heat transfer tube sample a and apply a preset stress to the heat transfer tube sample a; put the heat transfer tube sample a into the reaction kettle, and pour the pre-configured into the reaction kettle at the same time. A good solution for simulating the service environment of the heat transfer tube, specifically, the solution can be a sodium hydroxide solution, or a mixed solution (boric acid + lithium hydroxide + water) for simulating primary water; set the reaction Parameters such as temperature, pressure and flow rate in the kettle; after a preset time, take out the heat transfer tube sample a for observation.

During the experiment, multiple groups of control experiment groups can be set, wherein the variables of each group are the depth of the dent, the shape of the dent, the stress on the sample a of the heat transfer tube, the pH value of the solution, the concentration of the solution, the reaction The temperature in the kettle, the pressure in the reactor, the flow rate in the reactor and other parameters can be used to study the stress corrosion cracking mechanism of the heat transfer tube with dents under the coupling of multiple variables.

Referring to FIG. 7, in some embodiments, the stress corrosion fixture 900 includes a screw rod 910, a limit nut 920, an adjustment nut 930 and a compression spring 940. The screw rod 910 is used to pass through the heat transfer tube sample a, and the limit The nut 920 is threadedly connected to one end of the screw rod 910 and is used to limit the heat transfer tube sample a, the adjusting nut 930 is screwed to the other end of the screw rod 910, the compression spring 940 is sleeved on the screw rod 910, and one end of the compression spring 940 is against the Connected to the adjustment nut 930, the other end of the compression spring 940 is used to press the heat transfer tube sample a, wherein the heat transfer tube sample a is provided with a through hole for passing the screw 910, which can be adjusted by screwing during use. The nut 930 is used to adjust the stress on the heat transfer tube sample a. Specifically, spacers 950 are provided between the adjusting nut 930 and the compression spring 940 , between the compression spring 940 and the heat transfer tube sample a, and between the heat transfer tube sample a and the limit nut 920 . Among them, the preparation method, clamping method and stress calculation formula of heat transfer tube sample a can be found in the national standard GB/T15970.5-1998 "Corrosion Stress Corrosion Test of Metals and Alloys Part 5: Preparation of C-ring Samples" and Applications".

In the description of this specification, if referring to the description of reference terms such as "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example" and "some examples", it means A particular feature, structure, material, or characteristic described in connection with this embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, The scope of the invention is defined by the claims and their equivalents.

Claims (10)

1. A heat transfer tube dent preparation device, characterized in that, comprising: base(100); a bracket (200), the bracket (200) is arranged on the base (100); a swing rod (300), the upper end of the swing rod (300) is rotatably connected to the bracket (200), so that the swing rod (300) can swing relative to the bracket (200); A positioning fixture (400), the positioning fixture (400) is arranged on the base (100) and is located on the swing path of the swing rod (300), and the positioning fixture (400) is used for clamping the cross-section in the shape of a C-type heat transfer tube sample; A punch (500), the punch (500) includes a counterweight (510) and a punch body (520), the counterweight (510) being detachably connected to the lower end of the swing rod (300) , the punch main body (520) is arranged on the side of the counterweight part (510) facing the positioning fixture (400). 2. The heat transfer tube dent preparation device according to claim 1, wherein the punch (500) is connected to the swing rod (300) through bolts and nuts, and the swing rod (300) is The lower end is provided with a connecting portion (310), the connecting portion (310) is provided with a first mounting hole (311) for passing the bolt, and the top of the counterweight portion (510) is provided with a mounting hole (311) for embedding the bolt. The mounting groove (511) of the connecting portion (310), the counterweight portion (510) corresponding to the first mounting hole (311) is provided with a passage through the counterweight portion (510) for passing the bolts The second installation hole (512) of the connecting part (310) is embedded in the installation groove (511), the bolt is penetrated in the first installation hole (311) and the second installation In the hole (512), the nut is threadedly connected to the shank of the bolt, so that the weight portion (510) is sandwiched between the nut and the head of the bolt. 3. The heat transfer tube dent preparation device according to claim 1, characterized in that, the counterweight portion (510) is provided with two punch bodies (520), and the two punch bodies are (520) are respectively disposed on opposite sides of the counterweight portion (510). 4. The heat transfer tube dent preparation device according to claim 1, wherein a dial (600) is fixedly provided on the bracket (200) corresponding to the pendulum rod (300). 5. The heat transfer tube dent preparation device according to claim 1, characterized in that, the swing rod (300) is detachably connected to the bracket (200), and the swing rod (300) is connected to the An adjustment structure is arranged between the brackets (200), and the adjustment structure can adjust the height of the punch (500) when it is in a free hanging state. 6. The heat transfer tube dent preparation device according to claim 5, wherein the adjustment structure comprises a connecting shaft (700) rotatably arranged on the bracket (200), the connecting shaft ( 700) is provided with a third installation hole (710) for passing through the swing rod (300), the upper end of the swing rod (300) is passed through the third installation hole (710), and the connection The shaft (700) is provided with a fourth mounting hole (720) communicating with the third mounting hole (710), the fourth mounting hole (720) is a threaded hole, and the fourth mounting hole (720) is inside A jack screw whose end portion is abutted against the swing rod (300) is screwed. 7. The heat transfer tube dent preparation device according to claim 5, wherein the diameter of the lower part of the swing rod (300) is larger than the diameter of the upper part of the swing rod (300), and the swing rod (300) The lower part of the swing rod (300) is provided with an external thread structure, so that the lower part of the swing rod (300) can be installed with an external counterweight with a threaded hole. 8. The heat transfer tube dent preparation device according to claim 1, wherein the positioning fixture (400) comprises a positioning pin and a rod-shaped positioning body (410), the positioning body (410) facing the One side of the counterweight portion (510) is provided with an arc-shaped portion (420) for fitting the inner surface of the heat transfer tube sample, and the arc-shaped portion (420) is provided with a positioning pin for inserting the locating pin hole (430). 9. A test method for dent-induced stress corrosion cracking, characterized in that it comprises the following steps: Prepare heat transfer tube samples, and use the heat transfer tube of the steam generator to prepare a heat transfer tube sample with a C-shaped cross section; Impact dents, using the heat transfer tube dent preparation device according to any one of claims 1 to 8 to impact dents on the outer surface of the heat transfer tube sample; Apply stress to the heat transfer tube sample, use a stress corrosion fixture (900) to clamp the heat transfer tube sample and apply a preset stress to the heat transfer tube sample; Put the heat transfer tube sample into the reaction kettle, and at the same time pour the pre-configured solution for simulating the service environment of the heat transfer tube into the reaction kettle; Set parameters such as temperature, pressure and flow rate in the reactor; After a preset time, the sample of the heat transfer tube was taken out for observation. 10. The test method for dent-induced stress corrosion cracking according to claim 9, wherein the stress corrosion fixture (900) comprises a screw (910), a limit nut (920), an adjustment nut (930) and A compression spring (940), the screw rod (910) is used to pass through the heat transfer tube sample, and the limit nut (920) is threadedly connected to one end of the screw rod (910) and used to test the heat transfer tube The adjustment nut (930) is threadedly connected to the other end of the screw rod (910), the compression spring (940) is sleeved on the screw rod (910), and the compression spring (940) One end of the spring is abutted on the adjusting nut (930), and the other end of the compression spring (940) is used to press the heat transfer tube sample.

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