Method and device for testing hydrogen permeation of metal material under moisture condition

Abstract

The invention discloses a method for testing hydrogen permeation of a metal material under a moisture condition, which comprises the following steps of: contacting one surface of a tested sample with electrochemical liquid, and applying voltage to the electrochemical liquid; enabling the other surface of the tested sample to be in contact with moisture with set conditions for a period of time, and monitoring the hydrogen permeation current density of the tested sample in the period of time; acquiring the steady-state current density corresponding to the moisture; calculating a steady-state hydrogen diffusion flux based on the steady-state current density; calculating the surface adsorbed hydrogen concentration of the tested sample based on the steady-state hydrogen diffusion flux; and calculating the concentration of the diffusible hydrogen atoms in the tested sample based on the surface adsorption hydrogen concentration of the tested sample. Correspondingly, the invention further discloses a testing device for hydrogen permeation of the metal material under the moisture condition.

Description

Technical Field

[0001] The invention relates to a testing method and a device, and in particular to a hydrogen permeation testing method and a device. Background Art

[0002] During the service of wet gas pipelines, H2S, CO2 and other acidic gases greatly deteriorate the corrosion environment of metal pipes and increase the risk of hydrogen-induced cracking of pipes. This is because acidic gases form weak acids after dissolving in water, which can cause electrochemical corrosion to steel. The anode process of the reaction is the dissolution of iron and the formation of iron-sulfur compounds, and the cathode process is the hydrogen ion reduction reaction. In addition to causing electrochemical corrosion, H2S can also cause more harmful hydrogen-induced cracking (HIC) and sulfide stress corrosion cracking (SSC).

[0003] The use of hydrogen permeation testing will provide a more reliable basis for the study of hydrogen-induced cracking and SSC caused by acidic gases such as H2S. More importantly, through the research, more in-depth and more practical results can be obtained on hydrogen-induced damage to materials.

[0004] The electrochemical hydrogen permeation method proposed by Devanathan is currently widely used to measure hydrogen permeation. This method can determine the diffusion coefficient, permeation rate, surface concentration of hydrogen in metals and the amount of hydrogen permeation during the corrosion process.

[0005] However, the above method is only for hydrogen permeation under solution conditions and is not suitable for hydrogen permeation testing under wet conditions. Summary of the invention

[0006] One of the purposes of the present invention is to provide a test method for hydrogen permeation of metal materials under wet conditions, which is not only applicable to steel products in service under wet conditions, but also applicable to hydrogen permeation simulation tests of metal materials under other dry-wet mixed conditions. Through this method, the influence of factors such as humidity, temperature and acid gas concentration on hydrogen permeation current and other parameters of pipeline steel can be obtained, thereby analyzing and evaluating the hydrogen embrittlement risk of metal materials under different environments, and providing guidance for reducing the risk of hydrogen embrittlement of metal materials, such as pipeline steel, under service conditions.

[0007] In order to achieve the above object, the present invention provides a method for testing hydrogen permeation of metal materials under humid conditions, which comprises the steps of:

[0008] Bringing one surface of the test sample into contact with an electrochemical solution and applying a voltage to the electrochemical solution;

[0009] The other surface of the tested sample is contacted with moisture having set conditions for a period of time, and the hydrogen permeation current density of the tested sample during the period of time is monitored;

[0010] Obtaining the steady-state current density corresponding to the moisture;

[0011] Calculate the steady-state hydrogen diffusion flux based on the steady-state current density;

[0012] The surface adsorbed hydrogen concentration of the tested sample is obtained by calculation based on the steady-state hydrogen diffusion flux;

[0013] The concentration of diffusible hydrogen atoms in the tested sample is calculated based on the surface adsorbed hydrogen concentration of the tested sample.

[0014] In the present invention, the setting conditions of moisture may include: type, concentration, humidity and temperature of gas.

[0015] Furthermore, the testing method for hydrogen permeation of metal materials under humid conditions of the present invention further comprises the step of: calculating the hydrogen permeability based on the steady-state hydrogen diffusion flux.

[0016] Furthermore, in the test method for hydrogen permeation of metal materials under humid conditions described in the present invention, a voltage is applied to the electrochemical liquid until the monitored background current density drops to a set value, and then the other surface of the test sample is brought into contact with moisture having set conditions.

[0017] This measure is to make the final measurement result more accurate.

[0018] Furthermore, in the test method for hydrogen permeation of metal materials under humid conditions of the present invention, the humid gas is formed by heating and evaporating deionized water and mixing it with a test acidic gas.

[0019] In some more specific embodiments, a heating device is used to heat deionized water, and the humidity is controlled by controlling the heating temperature range and different heating times. After a liquid film is formed on the surface of the test sample, the acid gas required for the test is introduced, and the flow rate is controlled at 0-500 ml / min as required. The acid gas introduction time is controlled according to the test requirements, and the hydrogen permeation current is continuously monitored until it reaches stability, and the steady-state current density is recorded.

[0020] Furthermore, in the testing method for hydrogen permeation of metal materials under humid conditions described in the present invention, the electrochemical liquid is an alkaline liquid.

[0021] Furthermore, in the test method for hydrogen permeation of metal materials under humid conditions described in the present invention, before one surface of the test sample is brought into contact with the electrochemical liquid, the surface of the test sample is pretreated.

[0022] Another object of the present invention is to provide a testing device for hydrogen permeation of metal materials under humid conditions, which is used to implement the above-mentioned testing method.

[0023] Based on the above invention objectives, the present invention also provides a testing device for hydrogen permeation of metal materials under humid conditions, which comprises:

[0024] A hydrogen measuring electrolytic cell, which is arranged on one side of the sample to be measured, and the hydrogen measuring electrolytic cell contains an electrochemical liquid;

[0025] A hydrogen permeation electrolytic cell is arranged on the other side of the sample to be tested, the hydrogen permeation electrolytic cell is filled with moisture, and the hydrogen permeation electrolytic cell is connected to an air inlet pipeline and an air outlet pipeline;

[0026] The electrochemical workstation has a counter electrode and a reference electrode inserted into an electrochemical solution, and a working electrode used to connect with a sample to be tested. The electrochemical workstation also monitors hydrogen permeation current density.

[0027] Furthermore, the testing device of the present invention also includes a heating device, which heats the hydrogen permeation electrolytic cell.

[0028] Furthermore, the heating device is connected to a heating controller.

[0029] Furthermore, in the testing device described in the present invention, a flow control element is provided on the air intake pipeline.

[0030] The method and device for testing hydrogen permeation of metal materials under humid conditions of the present invention have the following beneficial effects:

[0031] The test method and device for hydrogen permeation of metal materials under wet conditions described in the present invention can analyze the effect of acidic gases with a certain humidity such as hydrogen sulfide and carbon dioxide on metal materials, such as hydrogen embrittlement of pipeline steel. The present invention realizes the simulation and reproduction of actual working conditions, and at the same time uses devices such as flow meters and temperature controllers to accurately control gas, moisture, etc., and can accurately control various influencing factors, thereby realizing accurate analysis of the effects of various influencing factors, and can provide guidance for pipeline steel safety evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The schematic diagram of the structure of the testing device for hydrogen permeation of metal materials under humid conditions according to the present invention in one embodiment is shown schematically.

[0033] Figure 2 The figure shows a hydrogen permeation curve of a specific example of the test method for hydrogen permeation of a metal material under humid conditions according to the present invention.

[0034] Figure 3 The figure shows a hydrogen permeation curve of another specific example of the testing method for hydrogen permeation of metal materials under humid conditions according to the present invention. DETAILED DESCRIPTION

[0035] The test method and device for hydrogen permeation of metal materials under humid conditions described in the present invention will be further explained and illustrated below in conjunction with the drawings and specific embodiments of the specification. However, such explanation and illustration do not constitute an improper limitation on the technical solution of the present invention.

[0036] Figure 1 The schematic diagram of the structure of the testing device for hydrogen permeation of metal materials under humid conditions according to the present invention in one embodiment is shown schematically.

[0037] like Figure 1 As shown, in this embodiment, the testing device for hydrogen permeation of metal materials under humid conditions includes:

[0038] The hydrogen measuring electrolytic cell 1 is arranged on one side of the sample 3 to be measured, and the hydrogen measuring electrolytic cell 1 contains an electrochemical liquid. The hydrogen permeation electrolytic cell 2 is arranged on the other side of the sample 3 to be measured, and the hydrogen permeation electrolytic cell 2 contains deionized water. The hydrogen permeation electrolytic cell 2 is connected to the air inlet pipeline 6 and the air outlet pipeline 7 respectively, and the air inlet pipeline 6 is provided with a flow control element 9. The counter electrode C and the reference electrode R of the electrochemical workstation 8 are inserted into the electrochemical liquid, and the working electrode W is connected to the sample 3 to be measured. The electrochemical workstation also monitors the hydrogen permeation current density. The heating device 4 is used to heat the hydrogen permeation electrolytic cell 2, and the heating device 4 is connected to the heating controller 5.

[0039] In some more specific embodiments, the heating device 4 is configured as a heating belt, so that it can be more conveniently wound around the outer wall of the hydrogen permeation electrolytic cell 2 .

[0040] In some more specific embodiments, the material of the hydrogen measurement electrolytic cell 1 may be polyethylene, and the material of the hydrogen permeation electrolytic cell 2 may be stainless steel.

[0041] Another embodiment of the present invention also provides a method for testing hydrogen permeation of metal materials under humid conditions, which comprises the steps of:

[0042] 100: Making a sample to be tested. In a specific example, the sample to be tested is made into a table tennis racket shape, with a diameter of 55 mm and a total length of 80 mm.

[0043] 200: Pre-treat the surface of the sample to be tested; in a specific example, use alcohol ultrasound for 15 minutes to remove surface oil on both sides of the surface, then use sandpaper to grind to 1000#, and polish for 10 minutes after double-sided grinding, and measure the thickness L of the sample to be tested.

[0044] 300: Place the sample under test in Figure 1 In the middle of the test device shown, a sealing ring and bolts are used to ensure that the specimen is tightened after installation.

[0045] Add alkaline liquid as electrochemical liquid to the hydrogen measuring electrolytic cell 1, for example, add 500 ml of 0.2 mol / L NaOH solution. The test method uses the current-time method, sets the potential to 0.2 V vs SCE, and uses an electrochemical workstation to monitor until the background current drops to the set value, for example, 1 uA / cm 2 . The background current is reduced to 1uA / cm 2 Then add 100m-500ml of deionized water to the hydrogen permeation electrolytic cell 2. Use the heating device 4 and the heating controller 5 to raise the temperature in the hydrogen permeation electrolytic cell 2 to the required temperature, for example, a temperature value within the range of 20°C-80°C, and control the humidity of the hydrogen permeation electrolytic cell 2 by controlling the heating time. After the liquid film is formed on the surface of the test sample, the acid gas required for the test is introduced, and the flow rate is controlled at 0-500ml / min according to the requirements. The time at this time is recorded, and the acid gas introduction time is controlled according to the test requirements. The hydrogen permeation current density is continuously monitored until it reaches stability, and the steady-state current density i corresponding to the moisture is obtained. ∞ .

[0046] 400: Based on steady-state current density i ∞ Calculation of the steady-state hydrogen diffusion flux J ∞ :

[0047]

[0048] Where F is the Faraday constant, which is 96500C / mol; n is the number of electrons transferred in the reaction.

[0049] 500: Based on steady-state hydrogen diffusion flux J ∞ Calculate the surface adsorbed hydrogen concentration C of the tested sample 0 :

[0050]

[0051]

[0052] Where, L represents the thickness of the sample being measured, and its unit parameter is cm; D eff is the effective diffusion coefficient, t 0.63 It is the time when the instantaneous hydrogen diffusion flux reaches 0.63 times the steady-state hydrogen diffusion flux, and its unit parameter is s. Compared with the thickness of the tested sample, its area is large enough, so it is believed that when the hydrogen permeation behavior reaches a steady state, a one-dimensional diffusion perpendicular to the sample penetration surface can be established. According to Fick's first law J = -D (dc / dx), and the hydrogen concentration on the test surface of the tested sample is 0, the adsorbed hydrogen concentration C on the surface of the tested sample can be calculated. 0 .

[0053] 600: Based on the surface adsorbed hydrogen concentration of the tested sample, the concentration of diffusible hydrogen atoms in the tested sample H is calculated. m :

[0054]

[0055] Where A represents the area of ​​one side of the sample being tested.

[0056] In addition, in some embodiments, the steady-state hydrogen diffusion flux J ∞ Calculation of hydrogen permeability

[0057]

[0058] Below, this technical solution will use specific embodiment data to further describe the technical solution of this case and prove the beneficial effects of this case:

[0059] Example 1

[0060] X70 pipeline steel was selected as the tested material to measure its hydrogen permeation curve and hydrogen embrittlement performance in H2S wet environment. The specific steps are as follows:

[0061] The samples were cut into a table tennis racket shape with a diameter of 55 mm and a total length of 80 mm.

[0062] The inner and outer surfaces of the sample to be tested were cleaned of surface oil using alcohol ultrasound for 15 minutes, and then sanded to 1000# with sandpaper. After double-sided sanding, the sample was polished for 10 minutes to measure the sample thickness L.

[0063] Place the sample under test in Figure 1 In the middle of the test device shown, a sealing ring and bolts are used to ensure that the specimen is tightened after installation.

[0064] Add 500 ml of 0.2 mol / L NaOH solution to the left hydrogen electrolytic cell 1, set the anode potential to 0.2 V vs SCE, and monitor using an electrochemical workstation until the background current drops to 1 uA / cm 2 .

[0065] Background current drops to 1uA / cm 2 Then, 200 ml of deionized water was added to the right hydrogen permeation electrolytic cell 2. The temperature was raised to 35° C. by using the heating device and the heating controller for 4 hours.

[0066] Open the gas cylinder and introduce H2S gas into the hydrogen permeation electrolytic cell 2 through the gas inlet pipe 6. The flow rate is controlled at 50 ml / min. The time at this time is recorded. The gas introduction time is controlled to 4 hours. The hydrogen permeation current density is continuously monitored until it reaches stability. The hydrogen permeation curve is obtained as shown in the figure below. Figure 2 As shown, a steady-state current density is obtained.

[0067] The results of various hydrogen permeation parameters calculated based on the steady-state current density are listed in Table 1.

[0068] Table 1. X70 hydrogen permeation parameters under H2S wet conditions

[0069]

[0070] Example 2

[0071] X52 pipeline steel was selected as the tested material to measure its hydrogen permeation curve and hydrogen embrittlement performance at different temperatures in a H2S wet environment. The specific steps are as follows:

[0072] The samples were cut into a table tennis racket shape with a diameter of 55 mm and a total length of 80 mm.

[0073] The inner and outer surfaces of the sample to be tested were cleaned of surface oil using alcohol ultrasound for 15 minutes, and then sanded to 1000# with sandpaper. After double-sided sanding, the sample was polished for 10 minutes to measure the sample thickness L.

[0074] Place the sample under test in Figure 1 In the middle of the test device shown, a sealing ring and bolts are used to ensure that the specimen is tightened after installation.

[0075] Add 500 ml of 0.2 mol / L NaOH solution to the left hydrogen electrolytic cell 1, set the anode potential to 0.2 V vs SCE, and monitor using an electrochemical workstation until the background current drops to 1 uA / cm 2 .

[0076] Background current drops to 1uA / cm 2 Then, 200 ml of deionized water was added to the right hydrogen permeation electrolytic cell 2. The temperature of the wet gas was controlled to 30° C., 35° C. and 40° C. respectively by using the heating device and the heating controller, and the heating time was 2 h.

[0077] Open the gas cylinder and introduce H2S gas into the hydrogen permeation electrolytic cell 2 through the gas inlet pipe 6. The flow rate is controlled at 50 ml / min. The time at this time is recorded. The gas introduction time is controlled to 1 hour. The hydrogen permeation current density is continuously monitored until it reaches stability. The hydrogen permeation curve is obtained as shown in the figure below. Figure 3 As shown, a steady-state current density is obtained.

[0078] The results of various hydrogen permeation parameters calculated based on the steady-state current density are listed in Table 2.

[0079] Table 2.

[0080]

[0081] It can be seen that the present invention can be used to analyze the effects of acidic gases with a certain humidity such as hydrogen sulfide and carbon dioxide on metal materials, such as hydrogen embrittlement of pipeline steel, thereby realizing the simulation and reproduction of actual working conditions. At the same time, devices such as flow meters and temperature controllers are used to accurately control gases, moisture, etc., and various influencing factors can be accurately regulated, thereby realizing accurate analysis of the effects of various influencing factors, and providing guidance for the safety evaluation of pipeline steel.

[0082] It should be noted that the prior art in the protection scope of the present invention is not limited to the embodiments given in the present application documents. All prior art that does not contradict the solutions of the present invention, including but not limited to prior patent documents, prior public publications, prior public uses, etc., can be included in the protection scope of the present invention.

[0083] In addition, the combination of the various technical features in this case is not limited to the combination described in the claims of this case or the combination described in the specific embodiments. All technical features recorded in this case can be freely combined or combined in any way unless there is a contradiction between them.

[0084] It should also be noted that the above-listed embodiments are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made therewith can be directly derived or easily associated with by those skilled in the art from the contents disclosed in the present invention, and all should belong to the protection scope of the present invention.

Claims

1. A method for testing hydrogen permeation of metal materials under humid conditions, characterized in that: Includes steps: Bringing one surface of the test sample into contact with an electrochemical solution and applying a voltage to the electrochemical solution; The other surface of the tested sample is contacted with moisture having set conditions for a period of time, and the hydrogen permeation current density of the tested sample during the period of time is monitored; Obtaining the steady-state current density corresponding to the moisture; Calculate the steady-state hydrogen diffusion flux based on the steady-state current density; The surface adsorbed hydrogen concentration of the tested sample is obtained by calculation based on the steady-state hydrogen diffusion flux; The concentration of diffusible hydrogen atoms in the tested sample is calculated based on the surface adsorbed hydrogen concentration of the tested sample.

2. The method for testing hydrogen permeation of metal materials under humid conditions as claimed in claim 1, characterized in that: The method further comprises the step of calculating the hydrogen permeability based on the steady-state hydrogen diffusion flux.

3. The method for testing hydrogen permeation of metal materials under humid conditions as claimed in claim 1, characterized in that: A voltage is applied to the electrochemical solution until the monitored background current density drops to a set value, and then the other surface of the sample under test is contacted with moisture having set conditions.

4. The method for testing hydrogen permeation of metal materials under humid conditions as claimed in claim 1, characterized in that: The moisture is formed by heating deionized water to evaporate and mixing with the test acid gas.

5. The method for testing hydrogen permeation of metal materials under humid conditions as claimed in claim 1, characterized in that: The electrochemical liquid is an alkaline liquid.

6. The method for testing hydrogen permeation of metal materials under humid conditions as claimed in claim 1, characterized in that: Before a surface of the test sample is brought into contact with the electrochemical solution, the surface of the test sample is pretreated.

7. A testing device for hydrogen permeation of metal materials under humid conditions, which implements the testing method according to any one of claims 1 to 6, characterized in that: The testing device comprises: A hydrogen measuring electrolytic cell, which is arranged on one side of the sample to be measured, and the hydrogen measuring electrolytic cell contains an electrochemical liquid; A hydrogen permeation electrolytic cell is arranged on the other side of the sample to be tested, the hydrogen permeation electrolytic cell is filled with moisture, and the hydrogen permeation electrolytic cell is connected to an air inlet pipeline and an air outlet pipeline; The electrochemical workstation has a counter electrode and a reference electrode inserted into an electrochemical solution, and a working electrode used to connect with a sample to be tested. The electrochemical workstation also monitors hydrogen permeation current density.

8. The testing device according to claim 7, characterized in that: The invention also comprises a heating device for heating the hydrogen permeation electrolytic cell.

9. The testing device according to claim 8, characterized in that: The heating device is connected with a heating controller.

10. The testing device according to claim 7, characterized in that: A flow control element is arranged on the air intake pipeline.

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