CN212159392U

CN212159392U - Experimental device for measuring fatigue crack propagation under high-temperature conductive solution

Info

Publication number: CN212159392U
Application number: CN202020286317.7U
Authority: CN
Inventors: 杨中燕; 张青; 周泓全; 王庆东; 张小康
Original assignee: Shanghai Cor Force Stress Corrosion Testing Equipment Co ltd
Current assignee: Shanghai Cor Force Stress Corrosion Testing Equipment Co ltd
Priority date: 2020-03-10
Filing date: 2020-03-10
Publication date: 2020-12-15
Anticipated expiration: 2030-03-10

Abstract

The utility model discloses an experimental device for measuring fatigue crack propagation in high-temperature conductive solution, which comprises a fixed bracket, a loading shaft, a conductive rod, a detection device for measuring the displacement of the conductive rod and a controller; one end of the loading shaft is fixed with the sample, and the other end of the loading shaft penetrates through the cover body and is connected with external power; one end of the conducting rod is connected to the sample, and the other end of the conducting rod penetrates through the cover body and is connected with the detection device; the loading shaft stretches the sample, fatigue cracks are generated on the sample under the action of the tensile force, and the displacement of the sample is converted into the displacement of the conducting rod and is detected by an external detection device. The deformation of the sample is led to the outside of the kettle body through the conducting rod, so that the deformation can be easily measured by the detection device, the data is read by the controller, the fatigue crack propagation rate of the sample can be solved through calculation, and the technical problem that the fatigue crack propagation measurement cannot be directly carried out on the sample under the condition of high-temperature conducting solution is solved.

Description

Experimental device for measuring fatigue crack propagation under high-temperature conductive solution

Technical Field

The utility model relates to a measure experimental apparatus of fatigue crack growth, be particularly useful for carrying out the measurement of fatigue crack growth to the CT sample under the condition of high temperature conducting solution.

Background

In many fields, many engineering components are often subjected to periodic loads, so that the fatigue crack of the components is initiated and propagated, and the engineering components are also likely to be corroded by a corrosive environment to cause accelerated fatigue crack propagation, so that the measurement of the fatigue crack propagation rate of the material in the special corrosive environment is a simulation of real working conditions and is extremely important for evaluating the performance of the material.

At present, two modes for measuring the fatigue crack propagation rate exist in the testing machine industry, one mode is a COD gauge measuring method, and the other mode is a DCPD measuring mode. The two modes generally adopt CT type samples, and are convenient to measure and calculate.

The COD gauge measurement mode adopts a COD gauge to directly measure the opening amount of the CT sample, obtains the relation between the opening amount and the crack length through elastic fracture mechanics, and substitutes the known opening amount of the CT sample into a formula to calculate the crack propagation length, so that the fatigue crack propagation of the CT sample can be indirectly measured. However, the COD gauge cannot be used in a high-temperature conductive solution, so that the fatigue crack propagation rate of the CT sample cannot be measured directly under the condition of the high-temperature conductive solution.

The principle of the DCPD measurement method is that constant current is applied to two ends of a sample to generate a constant electric field in the thickness direction of the sample, the potential distribution in a CT sample is influenced by the shape and the size of a crack, when the length of the crack changes, the potential changes, and the fatigue crack propagation of the CT sample is measured by the principle, but the DCPD measurement method cannot be applied to a conductive solution, so that the fatigue crack propagation rate of the CT sample cannot be measured by the DCPD measurement method on the conductive high-temperature conductive solution.

The measurement experiment for fatigue crack propagation of the CT sample has strict requirements on the accuracy of the measurement result, particularly the measurement difficulty for fatigue crack propagation of the CT sample under the condition of high-temperature conductive solution is very high, and almost all sensors cannot directly measure the fatigue crack propagation of the CT sample under the condition of high-temperature conductive solution.

Based on the above considerations, it is urgently needed to research an experimental device capable of measuring fatigue crack propagation under a high-temperature conductive solution.

SUMMERY OF THE UTILITY MODEL

The utility model provides an experimental device for measure fatigue crack extension under high temperature conducting solution can solve the above-mentioned defect among the prior art.

The technical scheme of the utility model as follows:

an experimental device for measuring fatigue crack propagation in a high-temperature conductive solution comprises a fixed support, a loading shaft, a conductive rod and a detection device for measuring the displacement of the conductive rod;

the fixed support is fixed on a cover body, the cover body covers a kettle body, the fixed support is positioned in the kettle body, and the sample is fixed on the fixed support; one end of the loading shaft is fixed with the sample, the other end of the loading shaft penetrates through the cover body and is connected with external power, and the loading shaft is connected with the cover body in a sliding mode and can slide up and down; the conduction rods are arranged in pairs, at least one pair of conduction rods is arranged, each pair of conduction rods comprises a first conduction rod and a second conduction rod, one end of each first conduction rod is connected to a preset position, close to the loading shaft, on the sample, and the other end of each first conduction rod penetrates through the cover body; one end of the second conduction rod is connected to a preset position, far away from the loading shaft, on the sample, and the other end of the second conduction rod penetrates through the cover body; fixing a sample in a kettle body of the reaction kettle through a fixing support, stretching the sample by the loading shaft under the action of external power, generating fatigue cracks on the sample under the action of the tension, converting the displacement of the sample into the relative displacement of the first conducting rod and the second conducting rod of each pair of conducting rods, and detecting the relative displacement by an external detection device; the device also comprises a controller, wherein the controller is in communication connection with the detection device, and reads the measurement result of the detection device according to the received electric signal fed back by the detection device.

The deformation of the sample is led out of the kettle body through the conducting rod, so that the deformation can be easily measured by the detection device, the data is read by the controller, the fatigue crack propagation rate of the sample can be solved through calculation, and the technical problem of performing fatigue crack propagation measurement on the CT sample under the condition of high-temperature conducting solution is solved.

Preferably, the fixed bolster includes fixed plate and a plurality of connecting rod, each the connecting rod is fixed respectively on the lid and to the internal extension of cauldron, the fixed plate is fixed on each the connecting rod, the sample is fixed on the fixed plate. A plurality of connecting rods can provide stable connection effect for the fixed plate to fix the sample in the reation kettle cauldron is internal stable.

Preferably, a plurality of the connecting rods are uniformly distributed along the circumferential direction of the cover body, and the fixing plate is fixed at the free end of each connecting rod. The connecting rod of equipartition makes the fixed plate under the pulling force of loading axle, makes its atress even to avoid producing the skew and influencing the test result at tensile in-process fixed plate, the free end at the connecting rod is fixed to the fixed plate simultaneously, receives the pulling force effect when the fixed plate, and the connecting rod can provide stable reaction force for the fixed plate, makes fixed bolster and sample can stabilize more.

Preferably, every of every pair the conduction pole in all be equipped with an extraction piece outside the cauldron body, be fixed with first extraction piece on the first conduction pole, be fixed with second extraction piece on the second conduction pole, first extraction piece the second extraction piece sets up with the mode of staggering along the axial, detection device includes the COD rule, the COD rule card is established first extraction piece with between the second extraction piece, be used for measuring every right the relative displacement volume of conduction pole. The detection device is difficult to directly measure the displacement of each conduction pole, leads out the piece through setting up, and the indirect measurement of COD rule again leads out the distance between the piece to it is every right to obtain the upper and lower displacement volume of conduction pole, has simple structure, and measuring result is more accurate advantage.

Preferably, each pair of the conducting rods is provided with a second fixing plate, the second fixing plate is located outside the kettle body, the first conducting rod and the second conducting rod are movably connected to the second fixing plate through a linear bearing respectively, and the first conducting rod and the second conducting rod can freely move upwards or downwards along the axial direction; a clamping block is fixed on the circumferential direction of the loading shaft, and the second fixing plate is fixed on the clamping block; when the loading shaft moves up and down, the second fixing plate, the linear bearing and the clasping block follow the loading shaft, so that accurate guide is provided for the first conducting rod and the second conducting rod.

Preferably, the test sample is connected with the fixing support and/or the loading shaft through a fixture fixing head respectively, a fixing rod is arranged on the fixture fixing head, a pin is arranged on the test sample, and the fixing rod and the pin are arranged perpendicular to the stretching direction respectively; the test sample fixing device is characterized by further comprising a connecting sheet, wherein the connecting sheet is provided with at least two through holes, and the through holes of the connecting sheet are respectively sleeved on the pin and the fixing rod, so that the test sample is fixed. The sample is fixed with the fixture fixing head through the connecting piece, and the fixture fixing head has the advantages of simple structure and stable connection.

Preferably, the upper end and the lower end of the sample are respectively provided with a through hole, the pin is fixed in the through holes, one end of the pin is connected with the fixture fixing head through the connecting piece, and the other end of the pin is connected with the first conducting rod or the second conducting rod. The conducting rod is led out of the kettle body through the pins fixed in pin holes at two ends of the sample, so that the problem that the conducting rod cannot be directly led out from the opening of the sample is solved, and the leading-out mode is simpler and more convenient. The fixing rod penetrates through the end part of the fixing head of the clamp, and two end parts of the fixing rod are connected with the pin through the connecting pieces respectively, so that the sample is stably fixed between the fixing support and the loading shaft.

Preferably, the conduction rod and the loading shaft are respectively and tightly connected with the kettle cover through O-shaped sealing rings. The conducting rod and the loading shaft can freely move up and down, and the O-shaped sealing ring is arranged concentrically with the conducting rod and the loading shaft respectively to play a role in sealing. The sealing mode of the O-shaped ring is adopted, and the positive pressure in the kettle is larger than the positive pressure in the kettle borne by the sealing mode of the corrugated pipe.

The friction effect takes place between the in-process that reciprocates between conduction pole, loading axle and the O type sealing washer, in order to prevent that O type sealing washer is overheated and inefficacy, still include a water-cooling jacket, the water-cooling jacket is fixed in the lid surface, O type sealing washer is located in the water-cooling jacket upper end notch, O type sealing washer with water-cooling jacket zonulae occludens, just, the conduction pole the loading axle respectively with correspond O type sealing washer zonulae occludens.

Preferably, the sample is connected to the first conducting rod and the second conducting rod through an L-shaped connector, and two free ends of the L-shaped connector are fixed to the sample and the first conducting rod or the second conducting rod, respectively. Connect through L type connecting piece, the displacement volume when the sample produced the crackle can be accurate transmission to the conduction pole to improve the accuracy of test. The first conducting rod and the second conducting rod of each pair of conducting rods are respectively arranged on two sides of the sample, so that the accuracy of the test is prevented from being influenced when the single side of the sample is stressed.

Compared with the prior art, the beneficial effects of the utility model are as follows:

the utility model discloses a simple and easy effectual device, draw the position of the pin of CT sample outside the cauldron body, measure the displacement difference between two pins of CT sample just directly to the upper and lower displacement volume of first conducting rod, second conducting rod outside the cauldron through detection device, measure the deflection of CT sample promptly, rethread formula and size conversion can solve the fatigue crack length of CT sample, and then realize the measurement to the fatigue crack growth rate of CT sample under the high temperature conducting solution environment, solved present COD rule measuring mode and DCPD measuring mode and can not directly carry out fatigue crack growth measuring current situation to the CT sample under the high temperature conducting solution; the relative displacement of the conduction rod can be easily measured by clamping the COD gauge between the two leading-out pieces, and the measurement is accurate and effective; in addition, the device adopts the sealing mode of O-shaped rings for the loading shaft and the conduction rod, and compared with the sealing mode of a corrugated pipe, the device bears larger positive pressure in the kettle; the method that the conducting rod is fixed in pin holes at two ends of the CT sample through pins to lead the conducting rod out of the kettle body is unprecedented, and the method solves the problem that the conducting rod cannot be directly led out from the opening of the CT sample, so that the leading-out mode is simpler and more convenient.

Of course, it is not necessary for any particular product to achieve all of the above-described advantages at the same time.

Drawings

FIG. 1 is a sectional view showing the overall structure of an experimental apparatus according to embodiment 1 of the present invention;

FIG. 2 is a schematic view of the overall structure of the experimental apparatus of embodiment 1 of the present invention;

fig. 3 is a schematic view of a CT sample according to embodiment 1 of the present invention;

FIG. 4 is a partial view of a CT sample holder according to embodiment 1 of the present invention;

FIG. 5 is a schematic view of a part of the experimental apparatus of example 1 of the present invention outside the autoclave body.

Reference numerals: a kettle body 1; a kettle cover transition disc 2; a lid body 3; a water cooling jacket 5; a COD gauge 6; a linear bearing 7; a loading shaft 8; a conductive rod 9; a sample pin 11; a CT sample 12; a hugging block 13; a second fixing plate 14; an O-ring 15; a clamp fixing head 16; a fixing lever 161; a full-thread screw 17; an L-shaped connector 18; a connecting piece 19; a perforation 191; a fixed bracket 20; a fixing plate 22; a connecting rod 21; a through hole 121; a first conductive rod 91; a second conductive rod 92; a first lead-out 101; a second lead-out member 102.

Detailed Description

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The present invention will be further described with reference to the following specific examples. It should be understood that these examples are only for illustrating the present invention, and are not intended to limit the scope of the present invention. In practical applications, the improvement and adjustment made by those skilled in the art according to the present invention still belong to the protection scope of the present invention.

Example 1

The embodiment provides an experimental device for measuring fatigue crack propagation in a high-temperature conductive solution, and referring to fig. 1-5, the experimental device comprises a fixed support 20, a loading shaft 8, a conductive rod 9 and a detection device for measuring the displacement of the conductive rod;

the fixed support 20 is fixed on a cover body 3, the cover body 3 covers a kettle body 1, the fixed support 20 is positioned in the kettle body 1, and the CT sample 12 is fixed on the fixed support 20; one end of the loading shaft 8 is fixed with the CT sample 12, the other end of the loading shaft penetrates through the cover body 3 and is connected with external power, and the loading shaft 8 is in sliding connection with the cover body 3 and can slide up and down; at least one pair of conducting rods 9 is arranged, and comprises a first conducting rod 91 and a second conducting rod 92, one end of the first conducting rod 91 is connected to the CT sample 12 and close to the preset position of the loading shaft 8, and the other end of the first conducting rod 91 penetrates through the cover body 3; the second conductive rod 92 has one end connected to the CT specimen 12 at a predetermined position away from the loading shaft 8 and the other end penetrating the cover 3. The loading shaft 8 stretches the CT sample 12 under the action of external power, cracks are generated on the CT sample 12, and the displacement of the CT sample 12 is converted into the displacement of the conducting rod 9 and is detected by an external detection device; the device also comprises a controller, the controller is electrically connected with the detection device, and the controller reads and displays the measurement result of the detection device according to the received electric signal fed back by the detection device.

The displacement of the CT sample 12 is converted into the vertical movement amount between the first conducting rod 91 and the second conducting rod 92, so that the vertical movement amount is measured by a detection device outside the kettle body 1, the data is read by a controller, and the fatigue crack propagation rate of the CT sample 12 can be solved through calculation, thereby realizing the measurement of the fatigue crack propagation of the CT sample under the condition of high-temperature conducting solution.

Specifically, referring to fig. 1, a high-temperature conductive corrosive solution is filled in a kettle body 1 of the reaction kettle, a kettle cover transition disc 2 is fixed on the kettle body 1 in a screw connection mode, and a kettle cover 3 is fixed on the kettle cover transition disc 2 in a screw connection mode, so that the kettle body 1, the kettle cover transition disc 2 and the kettle cover 3 jointly form a high-temperature closed environment. As shown in fig. 2, the fixing bracket 20 includes a fixing plate 22 and a plurality of connecting rods 21, the upper ends of the connecting rods 21 are fixed on the kettle cover 3 in a threaded connection manner, there are four connecting rods 21 in total, and the connecting rods are uniformly distributed below the kettle cover 3 with the central axis of the kettle cover 3 as a reference, and the lower ends of the four connecting rods 21 are fixed together with the fixing plate 22 in a threaded nut manner. The plurality of connecting rods 21 can provide stable connecting action for the fixing plate 22, so that the CT sample 12 is stably fixed in the reaction kettle body 1. The connecting rods 21 uniformly distributed enable the fixing plate 22 to be stressed uniformly under the tension of the loading shaft 8, so that the fixing plate 22 is prevented from being deviated in the stretching process to influence the test result.

As shown in fig. 3 and 4, one through hole 121 is provided at each of the upper and lower ends of the CT sample 12, one sample pin 11 is inserted into each of the two through holes 121, and the sample pin 11 and the CT sample 12 are fixed to each other by a screw nut. The CT sample 12 is connected to the fixing bracket 20 and the loading shaft 8 through a fixture fixing head 16, respectively, the fixture fixing head 16 is provided with a fixing rod 161 along a direction perpendicular to the axial direction, and the fixture fixing head 16 is provided with an internal thread in the axial direction. The center of the fixing plate 22 is connected with a full-thread screw 17, the full-thread screw 17 is fixed on the fixing plate 22 through a threaded connection mode, the upper clamp fixing head 16 is fixed on the loading shaft 8 through a threaded connection, and the lower clamp fixing head 16 is fixed on the full-thread screw 17 of the fixing plate 22 through a threaded connection. The CT sample fixing device further comprises a connecting piece 19, wherein the upper end and the lower end of the connecting piece 19 are respectively provided with a through hole 191, the through holes 191 of the connecting piece 19 are respectively hooked on the sample pin 11 and the fixing rod 161 and are fixed through nuts, and therefore the CT sample 12 is fixed between the fixing plate 22 and the loading shaft 8. Fix through the connection piece, have simple structure, connect stable advantage.

The fixing rod 161 is connected to the end of the fixture fixing head 16 in a penetrating manner and fixed on the fixture fixing head 16 in a threaded manner, so that two sides of the CT sample 12 are connected with the fixing rod 161 of the fixture head through a connecting piece 19, and the stability of connection between the CT sample 12 and the fixture fixing head 16 is further increased.

Preferably, a first leading-out piece 101 is fixed on the first conducting rod 91, a second leading-out piece 102 is fixed on the second conducting rod 92, the first leading-out piece 101 and the second leading-out piece 102 are arranged outside the kettle body 1 in a staggered mode along the axial direction, the detection device comprises a COD gauge 6, and the COD gauge 6 is clamped between the first leading-out piece 101 and the second leading-out piece 102 and used for measuring the relative displacement along the axial direction between the first conducting rod 91 and the second conducting rod 92. Through the mode that sets up the extraction, measure the distance of axial displacement between first extraction 101 and the second extraction 102 by COD rule 6 to obtain the upper and lower displacement volume of first transmission pole 91, second transmission pole 92, have simple structure, advantage that the measuring result is more accurate.

Referring to fig. 5, a second fixing plate 14 is disposed on the conducting rod 9, the second fixing plate 14 is located outside the reaction kettle body 1, the first conducting rod 91 and the second conducting rod 92 are movably connected to the second fixing plate 14 through a linear bearing 7, and the first conducting rod 91 and the second conducting rod 92 can freely move up or down along the axial direction. A clasping block 13 is fixed on the circumferential direction of the loading shaft 8, and a second fixing plate 14 is fixed on the clasping block; when the loading shaft 8 moves up and down, the second fixing plate 14, the linear bearing 7 and the clasping block 13 follow up, so as to provide accurate guidance for the first conductive rod 91 and the second conductive rod 92.

With continued reference to fig. 1, 2, and 5, the predetermined positions of the kettle cover 3 are respectively provided with a mounting hole (not shown in the figure), the first conducting rod 91, the second conducting rod 92, and the loading shaft 8 respectively penetrate through the kettle cover 3 in a clearance fit manner, and in order to achieve a sealing effect, the first conducting rod 91, the second conducting rod 92, and the loading shaft 8 are respectively and tightly connected with the kettle cover 3 through an O-ring 15. The friction action occurs among the loading shaft 8, the conduction rod 9 and the O-shaped sealing ring 15, and the water cooling jacket 5 is further included for preventing the O-shaped sealing ring 15 from being overheated and losing efficacy. The three water cooling jackets 5 are respectively fixed in the mounting holes of the kettle cover 3 in a threaded manner, the O-shaped sealing ring 15 is arranged at the upper end of the water cooling jacket 5, and the O-shaped sealing ring 15 is arranged in the notch at the upper end of the water cooling jacket 5 and is tightly matched with the water cooling jacket 5. The O-shaped sealing ring 15 is made of rubber, namely the loading shaft 8 and the conduction rod 9 can slide up and down in the O-shaped sealing ring 15 and can ensure the sealing property.

The CT sample 12 is connected to the first conductive rod 91 and the second conductive rod 92 through an L-shaped connector 18, and two free ends of the L-shaped connector 18 are fixed to the sample pin 11 of the CT sample 12 and the first conductive rod 91 or the second conductive rod 92, respectively. Through the connection of the L-shaped connecting piece 18, the displacement when the CT sample 12 cracks can be accurately transmitted to the conducting rod 9, so that the test accuracy can be improved. The first conductive rod 91 and the second conductive rod 92 are respectively arranged on two sides of the CT sample 12, so that the accuracy of the test is prevented from being influenced when the sample is stressed on one side.

The utility model discloses an experimental apparatus's working process as follows:

in the process that the loading shaft 8 stretches up and down under the action of external power, the loading shaft 8 drives the clamp fixing head 16 at the upper end to move together, the clamp fixing head 16 at the upper end drives the CT sample 12 to stretch through various connections as shown in FIG. 4, the deformed displacement of the CT sample 12 is transmitted to the conduction rod 9 through the sample pin 11, so that the displacement of the CT sample 12 is converted into the up-and-down movement of the conduction rod 9, the up-and-down movement of the conduction rod 9 drives the up-and-down movement of the leading-out piece 10, the up-and-down movement displacement difference of the first leading-out piece 101 and the second leading-out piece 102 is measured through the COD gauge 6 and is also the displacement difference of the first conduction rod 91 and the second conduction rod 92, namely the deformation of the CT sample 12, the measured value of the COD gauge 6 is transmitted to the controller through an electric signal, the controller reads the measured values of the two COD gauges 6, and the controller averages the measured values of the two COD gauges 6 to, finally, the deformation of the CT sample 12 is measured, and the opening of the CT sample is calculated. And then according to elastic fracture mechanics, the fatigue crack length of the CT sample can be solved through a formula and size conversion, and finally the measurement of the fatigue crack propagation rate of the CT sample in a high-temperature conductive solution is realized.

In this embodiment, the controller is of the type EAU-2200, and the brand: kelfu, the controller can also select current model, only needs to read the data of two sets of COD rule 6 and carries out and get the average value, again with the result show to the display screen can, the model of controller is not used for the restriction the utility model discloses a protection scope.

The above disclosure is only illustrative of the preferred embodiments of the present invention. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention. The present invention is limited only by the claims and their full scope and equivalents.

Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An experimental device for measuring fatigue crack propagation in a high-temperature conductive solution is characterized by comprising a fixed support, a loading shaft, a conductive rod and a detection device for measuring the displacement of the conductive rod;

the fixed support is fixed on a cover body, the cover body covers a kettle body, the fixed support is positioned in the kettle body, and the sample is fixed on the fixed support;

one end of the loading shaft is fixed with the sample, the other end of the loading shaft penetrates through the cover body and is connected with external power, and the loading shaft is connected with the cover body in a sliding mode and can slide up and down;

the conduction rods are arranged in pairs, at least one pair of conduction rods is arranged, each pair of conduction rods comprises a first conduction rod and a second conduction rod, one end of each first conduction rod is connected to a preset position, close to the loading shaft, on the sample, and the other end of each first conduction rod penetrates through the cover body; one end of the second conduction rod is connected to a preset position, far away from the loading shaft, on the sample, and the other end of the second conduction rod penetrates through the cover body;

the loading shaft stretches the sample under the action of external power, the sample generates fatigue cracks under the action of the tension, the displacement of the sample is converted into the relative displacement of the first conducting rod and the second conducting rod of each pair of conducting rods, and the relative displacement is detected by the external detection device;

the device also comprises a controller, wherein the controller is in communication connection with the detection device, and reads the measurement result of the detection device according to the received electric signal fed back by the detection device.

2. The experimental device for measuring the fatigue crack propagation under the high-temperature conductive solution as claimed in claim 1, wherein the fixing bracket comprises a fixing plate and a plurality of connecting rods, each connecting rod is fixed on the cover body and extends into the autoclave body, the fixing plate is fixed on each connecting rod, and the test sample is fixed on the fixing plate.

3. The experimental device for measuring the fatigue crack propagation under the high-temperature conductive solution as claimed in claim 2, wherein a plurality of the connecting rods are uniformly distributed along the circumferential direction of the cover body, and the fixing plate is fixed at the free end of each connecting rod.

4. The apparatus according to claim 1, wherein each of the conducting rods of each pair of conducting rods has an outlet, the first outlet is fixed to the first conducting rod, the second outlet is fixed to the second conducting rod, the first and second outlets are arranged in an axially staggered manner, and the detecting device comprises a COD gauge clamped between the first and second outlets for measuring a relative displacement of each pair of conducting rods.

5. The experimental device for measuring fatigue crack propagation under high-temperature conductive solution according to claim 1, wherein each pair of conducting rods is provided with a second fixing plate, the second fixing plate is located outside the kettle body, and the first conducting rod and the second conducting rod are movably connected to the second fixing plate through a linear bearing respectively; a clamping block is fixed on the circumferential direction of the loading shaft, and the second fixing plate is fixed on the clamping block; when the loading shaft moves up and down, the second fixing plate, the linear bearing and the clasping block follow up, so that accurate guide is provided for the first conducting rod and the second conducting rod.

6. The experimental device for measuring fatigue crack propagation under high-temperature conductive solution as claimed in claim 1, wherein the sample is connected to the fixing bracket and/or the loading shaft through a fixture fixing head, respectively, the fixture fixing head is provided with a fixing rod, the upper and lower ends of the sample are provided with pins, respectively, and the fixing rod and the pins are arranged perpendicular to the stretching direction; the test sample fixing device further comprises a connecting piece, wherein the connecting piece is provided with at least two through holes, and the at least two through holes of the connecting piece are respectively hooked on the pin and the fixing rod so as to fix the test sample.

7. The experimental device for measuring the fatigue crack propagation under the high-temperature conductive solution according to claim 6, wherein a through hole is respectively formed at the upper end and the lower end of the sample, the pin is fixed in the through hole, one end of the pin is connected with the fixture fixing head through the connecting piece, and the other end of the pin is connected with the first conducting rod or the second conducting rod; the fixing rod penetrates through the end part of the fixing head of the clamp, and two end parts of the fixing rod are connected with the pin through the connecting pieces respectively.

8. The experimental device for measuring fatigue crack propagation under high-temperature conductive solution according to claim 1, wherein each pair of the conductive rod and the loading shaft are tightly connected with the cover body through an O-shaped sealing ring respectively.

9. The experimental device for measuring the fatigue crack propagation under the high-temperature conductive solution as claimed in claim 8, further comprising a water cooling jacket, wherein the water cooling jacket is fixed on the outer surface of the cover body, the O-ring is disposed in a notch at the upper end of the water cooling jacket, the O-ring is tightly connected with the water cooling jacket, and each pair of the conduction rod and the loading shaft is tightly connected with the corresponding O-ring.

10. The experimental device for measuring fatigue crack propagation under high-temperature conductive solution according to claim 1, wherein the test specimen is connected to the first conductive rod and the second conductive rod through an L-shaped connector, and two free ends of the L-shaped connector are fixed to the test specimen and the first conductive rod or the second conductive rod respectively; the first conducting rod and the second conducting rod of each pair of conducting rods are respectively arranged on two sides of the sample, so that the accuracy of the test is prevented from being influenced when the single side of the sample is stressed.