In-situ stress corrosion monitoring system and monitoring method

Abstract

The invention relates to an in-situ stress corrosion monitoring system and method, the system comprises a stress measurement assembly, an electrochemical measurement assembly, a stress corrosion assembly and a control assembly, the electrochemical measurement assembly is used for placing a working electrode in the electrochemical measurement assembly in the stress corrosion assembly and providing an electrochemical environment for the stress corrosion assembly; the stress corrosion assembly is used for corroding the working electrode in the electrochemical environment; the stress measurement assembly is used for carrying out stress test on the corroded working electrode; the control assembly is connected with the stress measurement assembly, the electrochemical measurement assembly and the stress corrosion assembly and used for controlling work of all the assemblies. According to the invention, the test area is narrowed through the slit, so that the test area is smaller than the crack width, thereby improving the test precision of the stress corrosion cracking position; x-ray focusing before stress testing is carried out in time through the clamp base with the adjustable length, and the testing speed is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of stress and static load stress corrosion detection, and in particular relates to an in-situ stress corrosion monitoring system and a monitoring method. Background Art

[0002] Stress corrosion refers to the damage behavior caused by tensile stress in a corrosive medium. Under the action of the corrosive medium, corrosion pits often form on the surface of the material. At the same time, under the action of external loads, cracks often form at the bottom of the corrosion pits, leading to stress corrosion cracking. This is often the cause of major safety accidents such as bridge collapse, plane crashes, and pipeline leaks. There are often no signs before stress corrosion occurs. Once it occurs, the crack propagation rate is fast, and the stress causing damage is much smaller than the yield stress. Stress corrosion behavior is generally closely related to the loading force, loading time, and the material's own organizational structure. Although a large number of researchers have conducted relevant research on stress corrosion behavior, the location, time, and process of stress corrosion cracking need to be further explored.

[0003] As the name implies, stress corrosion is related to stress. Although the strain gauge method can measure surface stress, the strain gauge will corrode in a corrosive environment, which will affect the measurement results. Therefore, non-contact stress detection technology is more suitable for this condition. X-ray diffraction technology is a material analysis and detection technology that can calculate the stress magnitude by comparing the difference between the Debye ring under stress-free conditions and the deformed Debye ring under stress. However, there is currently no in-situ device and method for stress corrosion research in X-ray stress testing. In addition, a single electrochemical in-situ test has been used to study stress corrosion and its cracking behavior. Patent No. CN202410623959.4 discloses a stress corrosion sample preparation device and method that can be used for electrochemical testing, which can realize in-situ electrochemical testing during stress corrosion. Patent No. CN201910480721.X discloses an online monitoring device and analysis method for stress corrosion cracking based on electrochemical noise, which can distinguish different stages of stress corrosion crack extension through different types of current / potential noise peaks. However, a single electrochemical in-situ detection cannot determine the location of stress corrosion cracking and subsequent stress release. In order to further explore the stress corrosion cracking behavior, there is an urgent need for a device that can coordinate multiple in-situ detection functions for stress corrosion research. Summary of the invention

[0004] In order to overcome the above problems existing in the prior art, the present invention provides an in-situ stress corrosion monitoring system and a monitoring method, which are used to solve the above problems existing in the prior art.

[0005] An in-situ stress corrosion monitoring system, comprising: a stress measurement component, an electrochemical measurement component, a stress corrosion component and a control component.

[0006] The electrochemical measurement component is used to place the working electrode therein in the stress corrosion component and provide an electrochemical environment for the stress corrosion component;

[0007] The stress corrosion component is used to corrode the working electrode in the electrochemical environment;

[0008] The stress measurement assembly is used to perform stress testing on the corroded working electrode;

[0009] The control component is respectively connected to the stress measurement component, the electrochemical measurement component and the stress corrosion component to control the work of each component.

[0010] According to the aspects described above and any possible implementation, an implementation is further provided, wherein the stress measurement assembly includes an X-ray stress tester and a slit and a mechanical arm connected thereto, and the mechanical arm is used to adjust the height and angle of the X-ray stress tester and the slit.

[0011] According to the aspects described above and any possible implementation methods, an implementation method is further provided, wherein the stress corrosion assembly includes a corrosion container and a stress corrosion fixture, a positioning block, a main bolt, an auxiliary bolt and a fixture base arranged therein; one end of the main bolt and the auxiliary bolt are connected to the stress corrosion fixture, and the other end of the main bolt and the auxiliary bolt are connected to the positioning block arranged in the stress corrosion fixture; one end of the fixture base is connected to the stress corrosion fixture, and the other end is fixed to the corrosion container.

[0012] According to the aspects described above and any possible implementation method, an implementation method is further provided, wherein the electrochemical measurement component includes an annular platinum electrode, a reference electrode, a working electrode and an electrochemical workstation; the annular platinum electrode and the reference electrode are arranged inside the cavity of the corrosion container and are connected to the electrochemical workstation through a wire; the working electrode is fixed between the stress corrosion fixture and the positioning block, and is connected to the electrochemical workstation.

[0013] According to the above aspects and any possible implementation, an implementation is further provided, wherein the annular platinum electrode is arranged between the slit and the working electrode, the diameter of the central hole of the annular platinum electrode is 1 to 10 mm, and the width of the slit is 0.05 to 0.1 mm.

[0014] According to the aspects described above and any possible implementation, there is further provided an implementation, wherein the control component is a computer, and the system further comprises a motion platform connected to the computer, and the motion platform is disposed at the bottom of the corrosion container.

[0015] According to the aspects described above and any possible implementation method, an implementation method is further provided, wherein the stress corrosion component also includes four ceramic rods, two outer ceramic rods are connected to the four-point bending fixture by a key connection, and two inner ceramic rods are connected to the positioning block by a key connection, and the other sides of the inner and outer ceramic rods are in contact with the working electrode.

[0016] According to the aspects described above and any possible implementation method, an implementation method is further provided, wherein the robotic arm includes a motor and a reducer, and the control component controls the motor and the reducer so that the robotic arm can reciprocate in the horizontal, vertical and vertical directions, and the movement speed is 0.1mm / s to 0.5mm / s, thereby adjusting the position of the X-ray stress tester and the slit.

[0017] The present invention also provides a monitoring method of an in-situ stress corrosion monitoring system, which is implemented by the system, and includes: (1) fixing a working electrode using a stress corrosion fixture, a positioning block and a ceramic rod, adjusting the working electrode through an auxiliary bolt so that it remains horizontal in an unloaded state, and performing stress loading through a main bolt, selecting a fixture base of a corresponding length specification according to the loading force, connecting the stress corrosion fixture to a corrosion container, and pouring a corrosion solution into the corrosion container;

[0018] (2) Place the annular platinum electrode just above the stress loading area of ​​the working electrode, place the reference electrode inside the cavity of the corrosion container, turn on the computer and the X-ray stress tester, adjust the position of the motion platform, the angle and height of the robotic arm, so that the X-rays are emitted from the slit and the center hole of the annular platinum electrode to the area to be tested, and ensure that the X-ray diffraction line is emitted from the center hole of the annular platinum electrode and received by the X-ray stress tester;

[0019] (3) Pour the corrosion solution into the corrosion container so that the liquid level of the corrosion solution is higher than a certain height of the central area of ​​the working electrode, turn on the power of the electrochemical workstation, so that the corrosion solution, the reference electrode, the annular platinum electrode and the working electrode form a path and an oxidation-reduction reaction occurs, and start the stress and electrochemical impedance test. The computer receives the electrical signals from the X-ray stress tester, the robotic arm, the electrochemical workstation and the motion platform to output the cracking position and time, the stress distribution cloud map and the stress and impedance spectrum change curves over time.

[0020] According to the above aspects and any possible implementation manner, an implementation manner is further provided, wherein the certain height is 0.1 mm to 2 mm.

[0021] Beneficial Effects of the Invention

[0022] (1) The present invention is easy to operate and does not damage the surface of the material; at the same time, the device is suitable for different types of stress corrosion fixtures;

[0023] (2) In the present invention, the test area is reduced by the slit so that the test area is smaller than the crack width, thereby improving the test accuracy of the stress corrosion cracking position; the X-ray focusing before the stress test is carried out in time by the length-adjustable fixture base, thereby improving the test speed;

[0024] (3) The present invention obtains a stress distribution cloud map of the loading area to determine the location and cracking time of stress corrosion cracking, and can also obtain the in-situ change curve of the surface stress and electrochemical impedance spectrum over time during the stress corrosion process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the device for in-situ monitoring of surface stress and corrosion resistance during stress corrosion of the present invention;

[0026] Figure 2 It is a schematic diagram of the cross-section of part of the structure of the device.

[0027] The marks in the figure are: 1-X-ray stress tester, 2-slit, 3-mechanical arm, 4-annular platinum electrode, 5-reference electrode, 6-working electrode, 7-electrochemical workstation, 8-four-point bending fixture, 9-positioning block, 10-ceramic rod, 11-main bolt, 12-auxiliary bolt, 13-main thread, 14-auxiliary thread, 15-through hole thread, 16-fixture base, 17-corrosion container, 18-computer, 19-motion platform. DETAILED DESCRIPTION

[0028] In order to better understand the technical solution of the present invention, the content of the present invention includes but is not limited to the specific implementation methods described below, and similar technologies and methods should be considered to be within the scope of protection of the present invention. In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments.

[0029] It should be clear that the embodiments described in the present invention are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0031] The present invention provides an in-situ stress corrosion monitoring system, which comprises: a stress measurement component, an electrochemical measurement component, a stress corrosion component and a control component.

[0032] The electrochemical measurement component is used to place the working electrode therein in the stress corrosion component and provide an electrochemical environment for the stress corrosion component;

[0033] The stress corrosion component is used to corrode the working electrode in the electrochemical environment;

[0034] The stress measurement assembly is used to perform stress testing on the corroded working electrode;

[0035] The control component is respectively connected to the stress measurement component, the electrochemical measurement component and the stress corrosion component to control the work of each component.

[0036] Specifically, if Figure 1 As shown, the in-situ stress corrosion monitoring system includes a stress measurement component, an electrochemical measurement component, a stress corrosion component and a control component, and the control component is implemented by a computer 18;

[0037] The stress measurement assembly includes an X-ray stress tester 1, a slit 2 and a mechanical arm 3. The slit 2 is tightly connected to the X-ray stress tester 1 by welding, mortise and tenon connection, or bolt connection. The slit 2 is used to reduce the test area so that the test range is smaller than the crack width to determine the stress corrosion cracking position. The inside of the slit is rectangular. If the slit width is too large so that the test area is larger than the crack width, it will be impossible to accurately determine the position of crack initiation. Therefore, the slit width is selected to be 0.05mm to 0.1mm, and the corresponding slit width is selected according to the type of test material. The mechanical arm 3 includes a motor and a reducer, and is connected to a computer 18. The computer 18 controls the motor and the reducer so that the mechanical arm 3 can reciprocate horizontally, vertically, and vertically. The movement speed range is 0.1mm / s to 0.5mm / s, which satisfies the X-ray stress tester 1 and the slit 2 to achieve three-dimensional movement, and is convenient for the early parameter debugging of the stress test. The X-ray stress tester 1 can realize surface stress detection and has the characteristics of fast test speed, high portability, high sensitivity, etc. The test speed range is 2 min / point to 4 min / point. The X-ray stress tester 1 and the electrochemical workstation 7 are connected to the computer 18;

[0038] The stress corrosion assembly includes a corrosion stress fixture, a positioning block 9, a ceramic rod 10, a main bolt 11, an auxiliary bolt 12, a main thread 13, an auxiliary thread 14, a through-hole thread 15, a fixture base 16 and a corrosion container 17, wherein the corrosion stress fixture adopts different types of loading methods such as a three-point bending fixture, a four-point bending fixture, a U-bend fixture, etc. according to needs. The present invention preferably adopts a four-point bending fixture 8 to achieve; Figure 2 As shown, one end of the main bolt 11 passes through the through hole ( Figure 2The auxiliary bolt 12 is connected to the four-point bending fixture 8 at one end through the through-hole thread 15, and the other end of the main bolt 11 is connected to the positioning block 9 through the main thread 13. The main bolt 11 is used for stress loading, and the other end of the auxiliary bolt 12 is connected to the positioning block 9 through the auxiliary thread 14. The change in the surface deflection of the working electrode is calculated by the loading force. The auxiliary bolt 12 is used to adjust the working electrode 6 to remain horizontal in the unloaded state, which is convenient for reducing the uneven stress distribution caused by the stress loading process, and stress loading is performed through the main bolt 11; the fixture base 16 is connected to the four-point bending fixture 8 by bolt connection or welding. The present invention preferably connects by threaded connection, and the fixture base 16 is connected to the corrosion container 17 by threaded connection. The length specification of the fixture base 16 can be replaced accordingly according to the different loading forces of the working electrode 6, and the length range of the fixture base 16 is 10mm to 80mm. When the loading force of the working electrode 6 is large, a shorter fixture base 16 needs to be replaced. When the loading force is small, a longer fixture base 16 needs to be replaced. This is convenient for timely adjusting the height difference between the working electrode 6 to be tested and the surface of the corrosion solution under the premise of ensuring that the X-ray stress tester 1 does not move during stress testing, so as to quickly focus the rays and improve the test accuracy. The ceramic rods 10 include several, and four are provided in the present invention. Two outer ceramic rods 10 arranged on the outside are connected to the four-point bending fixture 8 through a key connection, and two inner ceramic rods 10 arranged on the inside are connected to the positioning block 9 through a key connection, and the inner and outer ceramic rods 10 are in contact with the working electrode 6, that is, the outer ceramic rod 10 on the outside is located above the end of the working electrode 6, and the inner ceramic rod 10 on the inside adjacent to the outer ceramic rod 10 on the outside is provided below the working electrode 6.

[0039] The stress corrosion assembly also includes a motion platform 19, which includes a driving motor. The motion platform 19 is connected to a computer 18 and has a built-in motor. The motion platform 19 is also connected to the bottom of the corrosion container 17 by welding or threading, so as to drive the corrosion container to move. The computer 18 controls the motor to make the motion platform 19 and the corrosion container 17 reciprocate in the horizontal and vertical directions, with a step speed of 0.5 mm / s to 1 mm / s, so as to realize stress testing in the horizontal and vertical directions.

[0040] The electrochemical measurement assembly includes an annular platinum electrode 4, a reference electrode 5, a working electrode 6 and an electrochemical workstation 7. The annular platinum electrode 4 and the reference electrode 5 act as cathode and anode respectively to generate redox reaction. The working electrode 6 corrodes. The reference electrode 5 controls the electrode potential of the working electrode 6. The electrochemical workstation 7 is used for power on and parameter control. The annular platinum electrode 4 and the reference electrode 5 are located inside the cavity of the corrosion container 17 and are connected to the electrochemical workstation 7 through a wire. The working electrode 6 is fixed by a four-point bending fixture 8, a positioning block 9 and a ceramic rod 10. The working electrode 6 is connected to the wire by welding or threading, and is connected to the electrochemical workstation 7. A 1 cm gap is reserved on the upper surface of the working electrode 6. 2 ~3cm 2 The electrochemical measurement is carried out in the area, and other parts such as welding parts are evenly coated by silicone coating or spraying to prevent the metal in other parts from being exposed to the corrosive liquid and affecting the test results; the outer ceramic rod 10 is connected to the four-point bending fixture 8 by a key connection, and the inner ceramic rod 10 is connected to the positioning block 9 by a key connection. The other side of the inner and outer ceramic rods 10 is in contact with the working electrode 6; one end of the computer 18 is connected to the X-ray stress tester 1 by a wire, and the other end is connected to the electrochemical workstation 7 by a wire. The electrochemical workstation 7 is used for power on and parameter control; the annular platinum electrode 4 is located inside the cavity of the corrosion container 17 and between the slit 2 and the working electrode 6. The incident and diffracted X-rays pass through the center hole of the annular platinum electrode 4, thereby realizing in-situ detection. The diameter of the center hole of the annular platinum electrode 4 should be determined according to the different materials of the working electrode 6 and the test crystal planes where different metals diffract, so as to meet the maximum width of the diffraction cone is less than the diameter of the center hole of the annular platinum electrode 4, and the diameter of the center hole is 1mm to 10mm. The working electrode 6 is a rectangular parallelepiped with a thickness of 0.5 mm to 25 mm. The working electrode 6 is made of steel or aluminum alloy. The length and width of the rectangular parallelepiped are 20 mm and 5 mm respectively, and the thickness is 1 mm or 10 mm. For details, please refer to the description of the following embodiments.

[0041] The computer 18 is used to start the X-ray stress tester 1, the robotic arm 3, the electrochemical workstation 7 and the motion platform 19, control the sliding distance of the motion platform 19, the angle and height of the robotic arm 3, transmit and identify the test results of the X-ray stress tester 1 and output the stress distribution cloud map on the computer 18. The software of the computer 18 converts and processes the electrical signals of the X-ray stress tester 1, the robotic arm 3, the electrochemical workstation 7 and the motion platform 19, and finally converts them into in-situ output stress and impedance spectrum change curves over time from the early stage of stress corrosion to the process of stress corrosion cracking.

[0042] Preferably, the system of the present invention also includes a software system, which is loaded into the computer 18. The software includes but is not limited to the control of system signal acquisition, data storage, processing and analysis, motion platform displacement control and output of analysis results.

[0043] As an embodiment disclosed in the present invention, the present invention discloses a monitoring method of an in-situ stress corrosion monitoring system, which is implemented by the system of the present invention and includes the following steps:

[0044] (1) The working electrode 6 is fixed by using a four-point bending fixture 8, a positioning block 9, and inner and outer ceramic rods 10. The working electrode 6 is adjusted by an auxiliary bolt 12 so that it remains horizontal in an unloaded state. A fixture base 16 of a corresponding length specification is selected according to a pre-set loading force, and the four-point bending fixture 8 is connected to a corrosion container 17;

[0045] Among them, the working electrode 6 is stress-loaded by the main bolt 11. The maximum elastic stress of the working electrode 6 during the loading process appears in the middle part of the working electrode. The maximum deflection of the working electrode 6 corresponding to different loading forces is calculated according to the loading stress calculation formula. The loading stress and the maximum deflection satisfy the following calculation formula:

[0046]

[0047] In the formula, σ max is the maximum elastic stress in the middle of the working electrode 6, is the quantity to be determined, y is the maximum deflection of the working electrode 6, the maximum deflection value is a known quantity, E is the elastic modulus, the elastic modulus is a known quantity, t is the thickness of the working electrode, H is the distance between the two outermost outer ceramic rods, and A is the distance between the two innermost inner ceramic rods.

[0048] (2) Place the annular platinum electrode 4 just above the stress loading area of ​​the working electrode 6, place the reference electrode 5 inside the cavity of the corrosion container 17, turn on the computer 18 and the X-ray stress tester 1, adjust the position of the motion platform 19, the angle and height of the mechanical arm 3, so that the X-rays emitted by the X-ray stress tester 1 are emitted from the slit 2 and the center hole of the annular platinum electrode 4 to the stress loading area, and ensure that the X-ray diffraction line is emitted from the center hole of the annular platinum electrode 4 and is received by the X-ray stress tester 1. The X-ray diffraction line is obtained for the X-ray stress tester 1 to perform stress calculation, and the X-ray stress tester 1 sends the calculation results to the computer 18;

[0049] (3) Pour the corrosion solution into the corrosion container 17 so that the liquid level of the corrosion solution is 0.1 mm to 2 mm higher than the central area of ​​the working electrode 6. Turn on the power of the electrochemical workstation 7 so that the corrosion solution, the reference electrode 5, the annular platinum electrode 4 and the working electrode 6 form a pathway and undergo redox reaction. Start stress and electrochemical impedance testing. The computer 18 receives electrical signals from the X-ray stress tester 1, the robotic arm 3, the electrochemical workstation 7 and the motion platform 19 to output the cracking position and time, the stress distribution cloud map and the stress and impedance spectrum change curves over time.

[0050] Furthermore, the method for determining the cracking position and cracking time is as follows: first, stress test is performed on the stress loading area of ​​the working electrode, the computer 18 controls the motor to make the motion platform 19 reciprocate in the horizontal and vertical directions, and the stepping speed meets 0.5mm / s~1mm / s, so as to realize stress test in the horizontal and vertical directions, and the X-ray stress tester 1 transmits the calculation results to the computer 18, and the software in the computer 18 automatically calculates the stress value. Subsequently, the software in the computer 18 records the initial stress value after loading, which is measured by the X-ray stress tester 1, and the stress value change tested by the X-ray stress tester 1 during the loading process is monitored in situ. The software in the computer 18 determines whether cracking occurs according to the decrease in the stress value at the corresponding position (>±20MPa), and finally outputs the stress distribution cloud map to determine the cracking position and cracking time. For tests under other loading stresses, the working electrode 6 is stress relaxed by the main bolt 11, the working electrode 6 is removed and replaced, and steps (1)-(3) are repeated. The following is explained in conjunction with a specific embodiment.

[0051] Example 1

[0052] A rectangular parallelepiped sample of steel material with a length, width and thickness of 20 mm, 5 mm and 1 mm respectively was used as the working electrode 6, and a 300 MPa stress loading was performed through a four-point bending fixture 8, with a slit width of 0.1 mm. The stress corrosion cracking time and position were determined, and the stress and impedance spectrum change curves during the stress corrosion cracking process were measured.

[0053] (1) Calculate the change in surface deflection of the working electrode 6 corresponding to the pre-set loading stress of 300 MPa, apply stress to the working electrode 6 through the main bolt 11, the height of the fixture base 16 is 50 mm, and the four-point bending fixture is connected to the corrosion container 17, and a 3.5 wt.% NaCl corrosion solution is poured into the corrosion container 17, and the liquid level of the corrosion solution is 0.5 mm higher than the central area of ​​the working electrode 6;

[0054] (2) Place the annular platinum electrode 4 just above the working electrode 6 and the stress loading area, and place the reference electrode 5 inside the cavity of the corrosion container 17. Turn on the computer 18 and the X-ray stress tester 1, adjust the position of the motion platform 19, and adjust the height and angle of the mechanical arm 3 so that the X-rays are emitted from the slit 2 and the center hole of the annular platinum electrode 4 to the area to be tested, and ensure that the X-ray diffraction line is emitted from the center hole of the annular platinum electrode 4 and is received by the X-ray stress tester;

[0055] (3) Turn on the electrochemical workstation, start stress and electrochemical impedance testing, and use the computer software to identify the cracking location (2 mm from the center line) and time (375 h). The computer 18 outputs the stress distribution cloud map and the stress and impedance spectrum change curves over time.

[0056] Example 2

[0057] A rectangular sample of aluminum alloy material with a length, width and thickness of 20 mm, 5 mm and 1 mm respectively was used as the working electrode 6, and a 200 MPa stress was applied through a four-point bending fixture 8, with a slit width of 0.08 mm. The stress corrosion cracking time and position were determined, and the stress and impedance spectrum change curves during the stress corrosion cracking process were measured.

[0058] (1) Calculate the change in surface deflection of the working electrode 6 corresponding to the pre-set loading stress of 200 MPa, apply stress to the working electrode 6 through the main bolt 11, the height of the fixture base 16 is 50 mm, and the four-bend fixture is connected to the corrosion container 17, and a 3.5 wt.% NaCl corrosion solution is poured into the corrosion container 17;

[0059] (2) Place the annular platinum electrode 4 just above the working electrode 6 and the stress loading area, and place the reference electrode 5 inside the cavity of the corrosion container 17. Turn on the computer 18 and the X-ray stress tester 1, adjust the position of the motion platform 19, and adjust the height and angle of the mechanical arm 3 so that the X-rays are emitted from the slit 2 and the center hole of the annular platinum electrode 4 to the area to be tested, and ensure that the X-ray diffraction line is emitted from the center hole of the annular platinum electrode 4 and is received by the X-ray stress tester;

[0060] (3) Turn on the electrochemical workstation, start stress and electrochemical impedance testing, and the computer software identifies the crack position (1.6 mm from the center line) and time (86 h), and outputs the stress distribution cloud map, stress and impedance spectrum change curves over time on the computer 18.

[0061] Example 3

[0062] A rectangular sample of aluminum alloy material with a length, width and thickness of 20 mm, 5 mm and 1 mm respectively was used as the working electrode 6, and a 100 MPa stress was applied through a four-point bending fixture 8, with a slit width of 0.05 mm. The stress corrosion cracking time and position were determined, and the stress and impedance spectrum change curves during the stress corrosion cracking process were measured.

[0063] (1) Calculate the change in surface deflection of the working electrode 6 corresponding to the pre-set loading stress of 100 MPa, apply stress to the working electrode 6 through the main bolt 11, the height of the fixture base 16 is 60 mm, and the four-bend fixture is connected to the corrosion container 17, and a 3.5 wt.% NaCl corrosion solution is poured into the corrosion container 17, and the liquid level of the corrosion solution is 0.5 mm higher than the central area of ​​the working electrode 6;

[0064] (2) Place the annular platinum electrode 4 just above the working electrode 6 and the stress loading area, and place the reference electrode 5 inside the cavity of the corrosion container 17. Turn on the computer 18 and the X-ray stress tester 1, adjust the position of the motion platform 19, and adjust the height and angle of the mechanical arm 3 so that the X-rays are emitted from the slit 2 and the center hole of the annular platinum electrode 4 to the area to be tested, and ensure that the X-ray diffraction line is emitted from the center hole of the annular platinum electrode 4 and is received by the X-ray stress tester;

[0065] (3) Turn on the electrochemical workstation, start stress and electrochemical impedance testing, and the computer software identifies the crack position (1.9 mm from the center line) and time (98 h), and outputs the stress distribution cloud map, stress and impedance spectrum change curves over time on the computer 18.

[0066] Example 4

[0067] Aluminum alloy material, a rectangular parallelepiped sample with a length, width and thickness of 20mm, 5mm and 10mm respectively, is used as the working electrode 6, and a 200MPa stress is applied through a four-point bending fixture 8, with a slit width of 0.08mm. The stress corrosion cracking time and position are determined, and the stress and impedance spectrum change curves during the stress corrosion cracking process are measured.

[0068] (1) Calculate the change in surface deflection of the working electrode 6 corresponding to the pre-set loading stress of 200 MPa, apply stress to the working electrode 6 through the main bolt 11, the height of the fixture base 16 is 45 mm, and the four-bend fixture is connected to the corrosion container 17, and a 3.5 wt.% NaCl corrosion solution is poured into the corrosion container 17, and the liquid level of the corrosion solution is 0.5 mm higher than the central area of ​​the working electrode 6;

[0069] (2) Place the annular platinum electrode 4 just above the working electrode 6 and the stress loading area, and place the reference electrode 5 inside the cavity of the corrosion container 17. Turn on the computer 18 and the X-ray stress tester 1, adjust the position of the motion platform 19, and adjust the height and angle of the mechanical arm 3 so that the X-rays are emitted from the slit 2 and the center hole of the annular platinum electrode 4 to the area to be tested, and ensure that the X-ray diffraction line is emitted from the center hole of the annular platinum electrode 4 and is received by the X-ray stress tester;

[0070] (3) Turn on the electrochemical workstation, start stress and electrochemical impedance testing, and use the computer software to identify the cracking position (0.8 mm from the center line) and time (105 h). The computer 18 outputs the stress distribution cloud map and the stress and impedance spectrum change curves over time.

[0071] Example 5

[0072] Aluminum alloy material, a rectangular parallelepiped sample with a length, width and thickness of 20mm, 5mm and 1mm respectively, was used as the working electrode 6, and a 200MPa stress loading was performed through a three-point bending fixture with a slit width of 0.08mm. The stress corrosion cracking time and position were determined, and the stress and impedance spectrum change curves during the stress corrosion cracking process were measured.

[0073] (1) Calculate the change in surface deflection of the working electrode 6 corresponding to the pre-set loading stress of 200 MPa, apply stress to the working electrode 6 through the main bolt 11, the height of the fixture base 16 is 50 mm, and the four-bend fixture is connected to the corrosion container 17, and a 5.0 wt.% NaCl corrosion solution is poured into the corrosion container 17;

[0074] (2) Place the annular platinum electrode 4 just above the working electrode 6 and the stress loading area, and place the reference electrode 5 inside the cavity of the corrosion container 17. Turn on the computer 18 and the X-ray stress tester 1, adjust the position of the motion platform 19, and adjust the height and angle of the mechanical arm 3 so that the X-rays are emitted from the slit 2 and the center hole of the annular platinum electrode 4 to the area to be tested, and ensure that the X-ray diffraction line is emitted from the center hole of the annular platinum electrode 4 and is received by the X-ray stress tester;

[0075] (3) Turn on the electrochemical workstation, start stress and electrochemical impedance testing, and use the computer software to identify the cracking location (1.5 mm from the center line) and time (72 h). The computer 18 outputs the stress distribution cloud map and the stress and impedance spectrum change curves over time.

[0076] The above description shows and describes several preferred embodiments of the present invention, but as mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not depart from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. An in-situ stress corrosion monitoring system, characterized in that: The system comprises: a stress measurement component, an electrochemical measurement component, a stress corrosion component and a control component. The electrochemical measurement component is used to place the working electrode therein in the stress corrosion component and provide an electrochemical environment for the stress corrosion component; The stress corrosion component is used to corrode the working electrode in the electrochemical environment; The stress measurement assembly is used to perform stress testing on the corroded working electrode; The control component is respectively connected to the stress measurement component, the electrochemical measurement component and the stress corrosion component to control the work of each component.

2. The in-situ stress corrosion monitoring system according to claim 1, characterized in that: The stress measurement assembly includes an X-ray stress tester and a slit and a mechanical arm connected thereto, wherein the mechanical arm is used to adjust the height and angle of the X-ray stress tester and the slit.

3. The in-situ stress corrosion monitoring system according to claim 1 or 2, characterized in that: The stress corrosion assembly includes a corrosion container and a stress corrosion fixture, a positioning block, a main bolt, an auxiliary bolt and a fixture base arranged therein; one end of the main bolt and the auxiliary bolt are connected to the stress corrosion fixture, and the other end of the main bolt and the auxiliary bolt are connected to the positioning block arranged in the stress corrosion fixture; one end of the fixture base is connected to the stress corrosion fixture, and the other end is fixed to the corrosion container.

4. The in-situ stress corrosion monitoring system according to claim 3, characterized in that: The electrochemical measurement component includes a ring-shaped platinum electrode, a reference electrode, a working electrode and an electrochemical workstation; the ring-shaped platinum electrode and the reference electrode are arranged inside the cavity of the corrosion container and are connected to the electrochemical workstation through a wire; the working electrode is fixed between the stress corrosion fixture and the positioning block as a working electrode, and is connected to the electrochemical workstation.

5. The in-situ stress corrosion monitoring system according to claim 4, characterized in that: The annular platinum electrode is arranged between the slit and the working electrode, the diameter of the central hole of the annular platinum electrode is 1-10 mm, and the width of the slit is 0.05-0.1 mm.

6. The in-situ stress corrosion monitoring system according to claim 4, characterized in that: The control component is a computer, and the system further comprises a motion platform connected to the computer, wherein the motion platform is arranged at the bottom of the corrosion container.

7. The in-situ stress corrosion monitoring system according to claim 4, characterized in that: The stress corrosion assembly also includes four ceramic rods, two outer ceramic rods are connected to the four-point bending fixture through a key connection, two inner ceramic rods are connected to the positioning block through a key connection, and the other sides of the inner and outer ceramic rods are in contact with the working electrode.

8. The in-situ stress corrosion monitoring system according to claim 2, characterized in that: The robotic arm includes a motor and a reducer. The control component controls the motor and the reducer so that the robotic arm can reciprocate in the horizontal, vertical and perpendicular directions. The movement speed is 0.1 mm / s to 0.5 mm / s, thereby adjusting the position of the X-ray stress tester and the slit.

9. A monitoring method for an in-situ stress corrosion monitoring system, characterized in that: The method is implemented by the system of any one of claims 1 to 8, comprising: (1) fixing the working electrode using a stress corrosion fixture, a positioning block and a ceramic rod, adjusting the working electrode to keep it horizontal in an unloaded state through an auxiliary bolt, and performing stress loading through a main bolt, selecting a fixture base of a corresponding length specification according to the magnitude of the loading force, connecting the stress corrosion fixture to a corrosion container, and pouring a corrosion solution into the corrosion container; (2) Place the annular platinum electrode just above the stress loading area of ​​the working electrode, place the reference electrode inside the cavity of the corrosion container, turn on the computer and the X-ray stress tester, adjust the position of the motion platform, the angle and height of the robotic arm, so that the X-rays are emitted from the slit and the center hole of the annular platinum electrode to the area to be tested, and ensure that the X-ray diffraction line is emitted from the center hole of the annular platinum electrode and received by the X-ray stress tester; (3) Pour the corrosion solution into the corrosion container so that the liquid level of the corrosion solution is higher than a certain height of the central area of ​​the working electrode, turn on the power of the electrochemical workstation, so that the corrosion solution, the reference electrode, the annular platinum electrode and the working electrode form a path and an oxidation-reduction reaction occurs, and start the stress and electrochemical impedance test. The computer receives the electrical signals from the X-ray stress tester, the robotic arm, the electrochemical workstation and the motion platform to output the cracking position and time, the stress distribution cloud map and the stress and impedance spectrum change curves over time.

10. The monitoring method of the in-situ stress corrosion monitoring system according to claim 9, characterized in that: The certain height is 0.1 mm to 2 mm.

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