Device for measuring micro-region hydrogen diffusion coefficient of welded joint, measuring method and application thereof

Abstract

The present invention provides a device for measuring the hydrogen diffusion coefficient in the micro-region of a welded joint, a measuring method thereof and an application. A cathode electrolyte is filled in a cathode cell, and the auxiliary electrode of the cathode cell is connected to the positive pole of a DC constant current power supply through a wire; an anode electrolyte is filled in an anode cell, and the auxiliary electrode and the reference electrode of the anode cell both extend into the anode electrolyte and are respectively connected to an electrochemical workstation through wires, and the electrochemical workstation is connected to a computer; circular truncated cone-shaped through holes are respectively formed oppositely on the side walls of the cathode cell and the anode cell, and a specimen to be tested is arranged between the through hole of the cathode cell and the through hole of the anode cell. The specimen to be tested is respectively connected to the negative pole of the DC constant current power supply and the electrochemical workstation through wires. By adjusting the cone angle range of the circular truncated cone-shaped through hole and the bottom diameter of the circular truncated cone, the hydrogen diffusion coefficient in a tiny region of the welded joint is measured. The area range of the micro-region exposed to the electrolyte is 0.20 - 1.13 cm<supgt;2< / supgt;, and the cone angle range of the circular truncated cone-shaped through hole in contact with the specimen to be tested is 30 - 70°.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical testing of metal corrosion, and more specifically to a device for determining a hydrogen diffusion coefficient of a micro-region of a welding joint, a determination method and an application thereof. Background Art

[0002] The corrosion problem of metal materials is prevalent in all areas of the national economy and society. The direct or indirect economic losses caused by corrosion failure are often incalculable, and will also cause serious damage to people's production and life. Since the presence of hydrogen cannot be avoided in the environmental medium, hydrogen embrittlement is the most common form of corrosion failure. Hydrogen embrittlement has no obvious signs before fracture, and is generally a sudden damage, and it is a brittle fracture that is not easy to detect. In the corrosion damage of metal welded joints, the number of sudden accident cases caused by hydrogen-induced fracture in local areas is particularly obvious. This is because under the action of welding thermal cycles, the welds, heat-affected zones and parent materials in the welded joints have different chemical compositions and microstructures, and the mechanical properties of each area are also significantly different. This inhomogeneity of microstructure and mechanical properties often leads to different adsorption and diffusion behaviors of hydrogen in each microregion of the welded joint. Therefore, paying more attention to the hydrogen penetration and cracking mechanism of each microregion of the welded joint can help researchers adopt more suitable welding processes or more effective protection measures to prevent the occurrence of local hydrogen embrittlement in the welded joint.

[0003] The hydrogen diffusion coefficient is the main parameter that characterizes the hydrogen permeation process. Generally, there are two main methods for measuring the hydrogen diffusion coefficient: the gas phase method and the electrochemical method. Compared with the former, which requires a high vacuum environment and expensive equipment, the latter is currently a more widely used and easier to operate hydrogen permeation technology. The electrochemical hydrogen permeation method for measuring the hydrogen diffusion coefficient was first proposed by Devanathan and Stachurski in 1962, using a double electrolytic cell to charge and detect the material. With the advancement of science and technology, most of the current electrochemical hydrogen permeation devices are improved on the basis of the Devanathan-Stachurski double electrolytic cell method. The principle of this improved dual electrolytic cell technology is: the test material is sandwiched between two electrolytic cells with circular holes as the working electrode, and the two sides of the working electrode are exposed to the electrolyte solution through the circular holes; the cathode electrolytic cell is used as a hydrogen charging cell, and a constant current is applied between the working electrode and the corresponding auxiliary electrode (usually a platinum electrode) to generate hydrogen atoms in the electrolyte, which are adsorbed on the surface of the working electrode and diffused into the material; the anode electrolytic cell is used as a detection cell, and a constant potential is applied between the working electrode and the auxiliary electrode to electrolyze the hydrogen atoms diffused from the hydrogen charging cell, and the corresponding current generated will be recorded in real time, thereby drawing a hydrogen diffusion curve. By analyzing this time-current curve containing the diffusion characteristics of hydrogen in the material, the relevant diffusion kinetic parameters, especially the hydrogen diffusion coefficient, can be obtained.

[0004] Among the many studies on hydrogen diffusion characteristics using the Devanathan-Stachurski double electrolytic cell method, no analysis of hydrogen diffusion behavior has been specifically conducted on welded joints and their micro-regions, especially for flat plate or steel pipe welded joints with small thickness. Each micro-region, especially the heat-affected zone, is affected by the size, and the extracted hydrogen permeation sample will be smaller. However, most of the current double electrolytic cell devices are designed for larger uniform materials, and the diameter of the circular holes between the double electrolytic cells is generally larger. The heat-affected zone of the welded joint is small, so this double electrolytic cell with a larger aperture cannot be used. Reducing the diameter of the circular hole of the electrolytic cell will block the current path between the electrolyte and the working electrode because the hydrogen bubbles generated on the surface of the working electrode cannot be discharged from the circular hole in time, making it impossible to collect data stably.

[0005] Although patent CN 104950024 A discloses an improved Devanathan-Stachurski double electrolytic cell device for measuring the hydrogen diffusion coefficient, it is not suitable for smaller welding heat affected zones due to its large circular hole diameter (about 2.3 cm).

[0006] Patent CN 109883942 A discloses a test method for electrochemical testing of micro-areas of welded joints based on a microscope. However, this method can only test the open circuit potential and polarization curve of the micro-area, and cannot obtain the hydrogen diffusion coefficient of each micro-area. Summary of the invention

[0007] The present invention overcomes the shortcomings of the prior art. The existing hydrogen diffusion coefficient determination method is not applicable to the welding heat affected zone with a small size, and the hydrogen diffusion coefficient of each micro-zone cannot be obtained. A device for determining the hydrogen diffusion coefficient of a welded joint micro-zone and its determination method and application are provided. By using an experimental device for hydrogen permeation of metal material micro-zones at room temperature and pressure, the hydrogen permeation process can be more quickly and reliably performed on the welded joint micro-zone exposed to the electrolyte. The exposed area range of the micro-zone is 0.20-1.13 cm 2 In order to obtain its hydrogen diffusion coefficient and clarify the hydrogen diffusion behavior and hydrogen embrittlement mechanism of the micro-region of the metal material welded joint.

[0008] The purpose of the present invention is achieved through the following technical solutions.

[0009] A device for measuring hydrogen diffusion coefficient of micro-area of ​​welding joint comprises a cathode electrolytic cell hydrogen charging system, an anode electrolytic cell hydrogen measuring system, a sample to be tested and a computer.

[0010] The cathode electrolytic cell hydrogen charging system comprises a DC constant current power supply, a cathode cell and a cathode cell auxiliary electrode, wherein the cathode cell is filled with a cathode electrolyte, the cathode cell auxiliary electrode extends into the cathode electrolyte, the cathode cell auxiliary electrode is connected to the positive electrode of the DC constant current power supply via a wire, and a cathode cell through hole is provided on the side wall of the cathode cell;

[0011] The anode electrolytic cell hydrogen measurement system comprises an electrochemical workstation, an anode cell, an anode cell auxiliary electrode and an anode cell reference electrode, wherein the anode cell is filled with an anode electrolyte, the anode cell auxiliary electrode and the anode cell reference electrode both extend into the anode electrolyte, the anode cell auxiliary electrode and the anode cell reference electrode are connected to the electrochemical workstation, and the electrochemical workstation is connected to the computer, an anode cell through hole is provided on the side wall of the anode cell, and the cathode cell through hole and the anode cell through hole are arranged opposite to each other;

[0012] The test sample is arranged between the cathode pool through hole and the anode pool through hole, the surface of the test sample with a nickel coating faces the anode pool, and the surface of the test sample without a nickel coating faces the cathode pool. The test sample is connected to the negative electrode of the DC constant current power supply and the electrochemical workstation through wires.

[0013] The exposed surface area of ​​the sample to be tested in contact with the cathode electrolyte and the anode electrolyte is 0.20-1.13 cm 2 .

[0014] A first communication sealing ring is further provided between the sample to be tested and the cathode pool through hole, and a second communication sealing ring is further provided between the sample to be tested and the anode pool through hole.

[0015] The current output range of the DC constant current power supply is 0-3A, and the control current output accuracy is 1mA.

[0016] The electrochemical workstation has a current measurement range of 0-3A, a current measurement accuracy of 10pA, a voltage output range of 0-30V, and a control voltage output accuracy of 0.01mV.

[0017] The cathode pool through hole and the anode pool through hole both adopt a truncated cone through hole structure, and the cone angle of the cathode pool through hole and the anode pool through hole ranges from 30 to 70 degrees.

[0018] The cathode electrolyte used 0.5 mol / L H 2 SO 4 With 3g / L NH 4 The mixed solution of SCN, the anode electrolyte is 0.1 mol / L NaOH solution.

[0019] The cathode pool and the anode pool are both made of acrylic glass.

[0020] The cathode pool auxiliary anode and the anode pool auxiliary electrode both use platinum mesh electrodes, and the first connecting sealing ring and the second connecting sealing ring both use silicone gaskets.

[0021] A method for determining the hydrogen diffusion coefficient of a welded joint micro-area is carried out according to the following steps:

[0022] Step 1: Make the small heat affected zone extracted from the weld joint into an area of ​​1.0 cm 2 The thin sheet sample with a thickness of 1.2 mm was polished to 1000# by sandpaper step by step, and then ultrasonically cleaned in acetone and alcohol solution respectively, and then the surface of the sample was electroplated with nickel coating, and one surface of the nickel-plated thin sheet sample was polished to 1000# sandpaper to remove the nickel coating on the surface, while the other surface retained the nickel coating, and finally the sample was ultrasonically cleaned in acetone and rinsed with deionized water to prepare a thin sheet to be tested;

[0023] Step 2, placing the thin sheet-like test sample prepared in step 1 between the first connecting sealing ring and the second connecting sealing ring, and making the surface of one side of the test sample with the nickel coating face the anode cell, and fixing the measuring device under the premise of ensuring good sealing and no leakage, and then installing the anode cell auxiliary electrode and the anode cell reference electrode in the anode cell, and connecting them with the test sample and the electrochemical workstation to form an anode electrolytic cell hydrogen measurement system, and connecting the anode electrolytic cell hydrogen measurement system to a computer;

[0024] Step 3, injecting 0.1 mol / L NaOH anolyte into the anode cell, adjusting the reference potential of the electrochemical workstation to 300 mV, and starting the entire anode electrolytic cell hydrogen measurement system;

[0025] Step 4: When the hydrogen permeation current value displayed by the computer drops below 1.0 μA, the recording is paused and the data recorded by the computer is cleared. Then, a cathode auxiliary electrode is installed in the cathode cell, and the positive and negative electrodes of the DC constant current power supply are connected to the cathode auxiliary electrode and the test sample respectively. At the same time, 0.5 mol / L H 2 SO 4 With 3g / L NH 4 The mixed solution of SCN was used as the cathode electrolyte. The DC constant current power supply was turned on and the output current density was controlled to be 5 mA / cm 2 , and restart recording test data;

[0026] Step 5, after the hydrogen permeation current data recorded by the computer in step 4 no longer increases with time and remains stable for a period of time, the hydrogen permeation experiment is terminated, the DC constant current power supply and the electrochemical workstation are turned off, and the experimental data are saved on the computer. Finally, the cathode electrolyte and the anode electrolyte in the cathode cell and the anode cell are emptied respectively, and the test sample sandwiched between the two electrodes is taken out. After processing the obtained data, the hydrogen diffusion curve is obtained, and the hydrogen diffusion coefficient of the micro-area of ​​the weld joint can be calculated using the known formula.

[0027] The beneficial effects of the present invention are as follows: compared with the prior art, the present invention has the following obvious outstanding substantial advantages:

[0028] a. The present invention designs a truncated cone-shaped through hole on the cell wall of the double electrolytic cell, which reduces the area of ​​the sample to be tested exposed to the solution and expands the escape space of hydrogen bubbles as much as possible, so that the influence of the accumulated hydrogen bubbles on the test results is reduced to a lower level, which greatly improves the accuracy and reliability of the test results of the micro area of ​​the weld joint;

[0029] b. The device of the present invention is simple in equipment, easy to process, convenient to assemble and low in cost;

[0030] c. The device of the present invention can achieve the purpose of testing the hydrogen diffusion characteristics of the material under different exposure areas by simultaneously adjusting the cone angle of the truncated cone through hole and the size of the diameter of the bottom surface of the truncated cone. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 1 is a schematic diagram of the structure of the device of the present invention, wherein 1 is a DC constant current power supply, 2 is a cathode pool, 3 is a cathode pool auxiliary electrode, 4 is a cathode electrolyte, 5 is a cathode pool through hole, 6 is a first connecting seal ring, 7 is an electrochemical workstation, 8 is a computer, 9 is an anode pool, 10 is an anode pool auxiliary electrode, 11 is an anode pool reference electrode, 12 is an anode electrolyte, 13 is a second connecting seal ring, and 14 is a sample to be tested;

[0032] Figure 2 Schematic diagram of the sampling method of different micro-areas of the weld joint of the present invention;

[0033] Figure 3 It is a hydrogen diffusion curve diagram obtained by measuring the micro area of ​​the weld joint using the present invention. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described below through specific embodiments.

[0035] Embodiment 1

[0036] A device for measuring hydrogen diffusion coefficient of a weld joint micro-area, comprising a cathode electrolytic cell hydrogen charging system, an anode electrolytic cell hydrogen measuring system, a sample to be tested 14 and a computer 8,

[0037] The cathode electrolytic cell hydrogen charging system comprises a DC constant current power supply 1, a cathode cell 2 and a cathode cell auxiliary electrode 3. The cathode cell 2 is filled with a cathode electrolyte 4, the cathode cell auxiliary electrode 3 extends into the cathode electrolyte 4, the cathode cell auxiliary electrode 3 is connected to the positive electrode of the DC constant current power supply 1 through a wire, and a cathode cell through hole 5 is opened on the side wall of the cathode cell 2;

[0038] The anode electrolytic cell hydrogen measurement system comprises an electrochemical workstation 7, an anode cell 9, an anode cell auxiliary electrode 10 and an anode cell reference electrode 11. The anode cell 9 is filled with an anode electrolyte 12. The anode cell auxiliary electrode 10 and the anode cell reference electrode 11 are both extended into the anode electrolyte 12. The anode cell auxiliary electrode 10 and the anode cell reference electrode 11 are connected to the electrochemical workstation 7. The electrochemical workstation 7 is connected to a computer 8. An anode cell through hole is opened on the side wall of the anode cell 9. The cathode cell through hole 5 and the anode cell through hole are arranged opposite to each other.

[0039] The test sample 14 is arranged between the cathode pool through hole 5 and the anode pool through hole, the surface of the test sample 14 with nickel coating faces the anode pool 9, and the surface of the test sample 14 without nickel coating faces the cathode pool 2. The test sample 14 is connected to the negative pole of the DC constant current power supply 1 and the electrochemical workstation 7 through wires.

[0040] Embodiment 2

[0041] Based on the first embodiment, the exposed surface area of ​​the test sample 14 in contact with the cathode electrolyte 4 and the anode electrolyte 12 is 0.20-1.13 cm 2 .

[0042] A first communication sealing ring 6 is further provided between the sample to be tested 14 and the cathode cell through hole 5, and a second communication sealing ring 13 is further provided between the sample to be tested 14 and the anode cell through hole.

[0043] The current output range of the DC constant current power supply 1 is 0-3A, and the control current output accuracy is 1mA.

[0044] The current measurement range of the electrochemical workstation 7 is 0-3A, the current measurement accuracy is 10pA, the voltage output range is 0-30V, and the control voltage output accuracy is 0.01mV.

[0045] Embodiment 3

[0046] On the basis of the second embodiment, the cathode pool through hole 5 and the anode pool through hole both adopt a truncated cone through hole structure, and the cone angle of the cathode pool through hole 5 and the anode pool through hole ranges from 30° to 70°.

[0047] The cathode electrolyte 4 uses 0.5 mol / L H 2 SO4 With 3g / L NH 4 The mixed solution of SCN, the anolyte 12 is a 0.1 mol / L NaOH solution.

[0048] The cathode pool 2 and the anode pool 9 are both made of acrylic glass.

[0049] The cathode pool auxiliary anode 3 and the anode pool auxiliary electrode 10 both use platinum mesh electrodes, and the first communication sealing ring 6 and the second communication sealing ring 13 both use silicone gaskets.

[0050] Embodiment 4

[0051] A method for determining the hydrogen diffusion coefficient of a welded joint micro-area is carried out according to the following steps:

[0052] Step 1, according to Figure 2 The sampling method is to make the small heat-affected zone extracted from the weld joint into a sample with an area of ​​1.0 cm 2 The thin sheet sample with a thickness of 1.2 mm was polished to 1000# by sandpaper step by step, and then ultrasonically cleaned in acetone and alcohol solution respectively, and then the surface of the sample was electroplated with nickel coating, and one surface of the nickel-plated thin sheet sample was polished to 1000# sandpaper to remove the nickel coating on the surface, while the other surface retained the nickel coating, and finally the sample was ultrasonically cleaned in acetone and rinsed with deionized water to prepare a thin sheet to be tested;

[0053] Step 2, placing the thin sheet-like test sample prepared in step 1 between the first connecting sealing ring and the second connecting sealing ring, and making the surface of one side of the test sample with the nickel coating face the anode cell, and fixing the measuring device under the premise of ensuring good sealing and no leakage, and then installing the anode cell auxiliary electrode and the anode cell reference electrode in the anode cell, and connecting them with the test sample and the electrochemical workstation to form an anode electrolytic cell hydrogen measurement system, and connecting the anode electrolytic cell hydrogen measurement system to a computer;

[0054] Step 3, injecting 0.1 mol / L NaOH anolyte into the anode cell, adjusting the reference potential of the electrochemical workstation to 300 mV, and starting the entire anode electrolytic cell hydrogen measurement system;

[0055] Step 4: When the hydrogen permeation current value displayed by the computer drops below 1.0 μA, the recording is paused and the data recorded by the computer is cleared. Then, a cathode auxiliary electrode is installed in the cathode cell, and the positive and negative electrodes of the DC constant current power supply are connected to the cathode auxiliary electrode and the test sample respectively. At the same time, 0.5 mol / L H 2 SO 4 With 3g / L NH 4The mixed solution of SCN was used as the cathode electrolyte. The DC constant current power supply was turned on and the output current density was controlled to be 5 mA / cm 2 , and restart recording test data;

[0056] Step 5, after the hydrogen permeation current data recorded by the computer in step 4 no longer increases with time and remains stable for a period of time, the hydrogen permeation experiment is terminated, the DC constant current power supply and the electrochemical workstation are turned off, and the experimental data are saved on the computer. Finally, the cathode electrolyte and the anode electrolyte in the cathode pool and the anode pool are emptied respectively, and the test sample sandwiched between the two electrodes is taken out. After processing the obtained data, the hydrogen diffusion curve is obtained, as shown in FIG. Figure 3 As shown, the hydrogen diffusion coefficient of the micro-region of the weld joint can be calculated using the known formula.

[0057] The present invention is described above by way of example. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by those skilled in the art without inventive effort falls within the protection scope of the present invention.

Claims

1. A device for measuring the hydrogen diffusion coefficient of a welded joint micro-area, Features: It includes the cathode electrolytic cell hydrogen charging system, the anode electrolytic cell hydrogen measuring system, the test sample and the computer. The cathode electrolytic cell hydrogen charging system comprises a DC constant current power supply, a cathode cell and a cathode cell auxiliary electrode, wherein the cathode cell is filled with a cathode electrolyte, the cathode cell auxiliary electrode extends into the cathode electrolyte, the cathode cell auxiliary electrode is connected to the positive electrode of the DC constant current power supply via a wire, and a cathode cell through hole is provided on the side wall of the cathode cell; The anode electrolytic cell hydrogen measurement system comprises an electrochemical workstation, an anode cell, an anode cell auxiliary electrode and an anode cell reference electrode, wherein the anode cell is filled with an anode electrolyte, the anode cell auxiliary electrode and the anode cell reference electrode both extend into the anode electrolyte, the anode cell auxiliary electrode and the anode cell reference electrode are connected to the electrochemical workstation, and the electrochemical workstation is connected to the computer, an anode cell through hole is provided on the side wall of the anode cell, and the cathode cell through hole and the anode cell through hole are arranged opposite to each other; The test sample is arranged between the cathode pool through hole and the anode pool through hole, the surface of the test sample with a nickel coating faces the anode pool, and the surface of the test sample without a nickel coating faces the cathode pool, and the test sample is connected to the negative pole of the DC constant current power supply and the electrochemical workstation through wires respectively; the cathode pool through hole and the anode pool through hole both adopt a truncated cone through hole structure, and the cone angle range of the cathode pool through hole and the anode pool through hole is 30-70°.

2. A device for measuring hydrogen diffusion coefficient of a weld joint micro-area according to claim 1, Features: The exposed surface area of ​​the sample to be tested in contact with the cathode electrolyte and the anode electrolyte is 0.20-1.13 cm2.

3. A device for measuring hydrogen diffusion coefficient of a welded joint micro-area according to claim 1, Features: A first communication sealing ring is further provided between the sample to be tested and the cathode pool through hole, and a second communication sealing ring is further provided between the sample to be tested and the anode pool through hole.

4. A device for measuring hydrogen diffusion coefficient of a weld joint micro-area according to claim 1, Features: The current output range of the DC constant current power supply is 0-3A, and the control current output accuracy is 1mA; the current measurement range of the electrochemical workstation is 0-3A, and the current measurement accuracy is 10pA, the voltage output range is 0-30V, and the control voltage output accuracy is 0.01mV.

5. The device for measuring the hydrogen diffusion coefficient of a welded joint micro-area according to claim 1, Features: The cathode electrolyte is a mixed solution of 0.5 mol / L H2SO4 and 3 g / L NH4SCN, and the anode electrolyte is a 0.1 mol / L NaOH solution.

6. A device for measuring hydrogen diffusion coefficient of a weld joint micro-area according to claim 1, Features: The cathode pool and the anode pool are both made of acrylic glass.

7. A device for measuring hydrogen diffusion coefficient of a weld joint micro-area according to claim 3, Features: The cathode pool auxiliary electrode and the anode pool auxiliary electrode both use platinum mesh electrodes, and the first connecting sealing ring and the second connecting sealing ring both use silicone gaskets.

8. A method for measuring the hydrogen diffusion coefficient of a weld joint micro-area based on the measuring device according to any one of claims 1 to 7, Features: Follow the steps below: Step 1, the tiny heat-affected zone extracted from the weld joint is made into a thin sheet sample with an area of ​​1.0 cm2 and a thickness of 1.2 mm, which is polished step by step to 1000# with sandpaper, and then ultrasonically cleaned in acetone and alcohol solution respectively, and then the surface of the sample is electroplated with nickel coating, and one surface of the nickel-plated thin sheet sample is polished to 1000# sandpaper to remove the nickel coating on the surface, while the other surface retains the nickel coating, and finally the sample is ultrasonically cleaned in acetone and rinsed with deionized water to make a thin sheet of test sample; Step 2, placing the thin sheet-like test sample prepared in step 1 between the first connecting sealing ring and the second connecting sealing ring, and making the surface of the test sample with the nickel coating face the anode cell, fixing the measuring device under the premise of ensuring good sealing and no leakage, then installing the anode cell auxiliary electrode and the anode cell reference electrode in the anode cell, and connecting them with the test sample and the electrochemical workstation to form an anode electrolytic cell hydrogen measurement system, and connecting the anode electrolytic cell hydrogen measurement system to a computer; Step 3, inject 0.1 mol / L NaOH anolyte into the anode cell, adjust the reference potential of the electrochemical workstation to 300 mV, and start the entire anode electrolytic cell hydrogen measurement system; Step 4, when the hydrogen permeation current value displayed by the computer drops below 1.0 μA, the recording is suspended and the data recorded by the computer is cleared, and then a cathode auxiliary electrode is installed in the cathode cell, and the positive and negative electrodes of the DC constant current power supply are connected to the cathode auxiliary electrode and the test sample respectively, and at the same time, a mixed solution of 0.5 mol / L H2SO4 and 3 g / L NH4SCN is injected into the cathode cell as a cathode electrolyte, and the DC constant current power supply is turned on, and the current density of its output is controlled to be 5 mA / cm2, and the test data is recorded again; Step 5, after the hydrogen permeation current data recorded by the computer in step 4 no longer increases with time and remains stable for a period of time, the hydrogen permeation experiment is terminated, the DC constant current power supply and the electrochemical workstation are turned off, and the experimental data are saved on the computer. Finally, the cathode electrolyte and the anode electrolyte in the cathode cell and the anode cell are emptied respectively, and the test sample sandwiched between the two electrodes is taken out. After processing the obtained data, the hydrogen diffusion curve is obtained, and the hydrogen diffusion coefficient of the micro-area of ​​the weld joint can be calculated using the known formula.

9. A device for determining the hydrogen diffusion coefficient of a micro-region of a weld joint as described in any one of claims 1 to 7, which belongs to the application in the field of electrochemical testing technology for metal corrosion.

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