Method for testing hydrogen absorption and hydrogen diffusion parameters of metal under stress field

Abstract

The application belongs to the technical field of material performance testing, and provides a method for testing hydrogen absorption and hydrogen diffusion parameters of metal under a stress field. The method extracts a sample after hydrogen removal, performs compression loading, controls hydrogen concentration during gas-phase hydrogen charging, performs short-time and long-time heat preservation diffusion in stages, tests the sample, sequentially measures hydrogen distribution before hydrogen charging, after hydrogen charging, after short-time heat preservation, and after long-time heat preservation, analyzes stress distribution of the self-loaded sample by using a finite element method, calculates hydrogen absorption rates at different stresses, and fits a change relationship formula of the hydrogen absorption rate with respect to stress parameters, establishes a relationship between hydrogen chemical potential and stress, constructs a finite element model with the distribution after hydrogen charging as an initial state, uses a flux equation, iteratively adjusts a diffusion coefficient related to stress, matches a simulated short-time diffusion distribution with actual test data, and determines a change rule of the diffusion coefficient with respect to stress. The application can meet the requirements of high-temperature testing and simultaneous testing of multiple stresses.

Description

Technical Field

[0001] This application belongs to the field of materials performance testing technology, and in particular relates to a method for testing hydrogen absorption and hydrogen diffusion parameters of metals under stress. Background Technology

[0002] Zirconium alloys and metals with similar hydrogen absorption properties (such as titanium and yttrium, hereinafter collectively referred to as zirconium-like alloys) readily absorb hydrogen at higher temperatures. Hydrogen-induced delayed cracking is one of the key mechanisms of failure in zirconium-like alloys. Stress has a significant impact on hydrogen absorption, hydrogen diffusion, and hydrogen redistribution (approximate to the distribution of hydrogen chemical potential) in materials. Therefore, it is crucial to accurately measure parameters such as hydrogen absorption, hydrogen diffusion, and hydrogen chemical potential of metallic materials under stress.

[0003] Currently, the main method for this test involves applying a uniform stress field to the test area of ​​the material, then using a dual-electrolysis cell method to test various parameters of hydrogen permeation, and finally obtaining the influence of stress on these parameters. However, existing methods have several problems:

[0004] First, the testing temperature of the dual electrolytic cell method is usually no more than 95°C, which is difficult to meet the requirements of high-temperature testing and cannot test zirconium-like alloys that diffuse very slowly at low temperatures.

[0005] Second, each test targets only one type of stress, which is inefficient.

[0006] Third, it cannot test the chemical potential of hydrogen under different stress conditions, making it difficult to apply to practical devices under complex stress. Summary of the Invention

[0007] The purpose of this application is to overcome the shortcomings of the prior art and provide a method for testing the hydrogen absorption and diffusion parameters of metals under stress, so as to meet the needs of high-temperature testing and simultaneous testing of multiple stresses.

[0008] To achieve the above objectives, this application provides the following technical solution:

[0009] A method for testing hydrogen absorption and diffusion parameters of metals under stress, comprising:

[0010] Step 1: After the sample is dehydrogenated by vacuum thermal extraction, it is processed into a sample, compressed and loaded, hydrogen is charged in the gas phase and the hydrogen concentration is controlled, and short-term and long-term heat preservation diffusion is carried out in stages.

[0011] Step 2: Test the sample and measure the hydrogen distribution in sequence before hydrogen charging, after hydrogen charging, and after short-term and long-term heat preservation.

[0012] Step 3: Analyze the stress distribution of the self-loaded sample using the finite element method, calculate the hydrogen absorption rate at different stresses, and fit the relationship between the hydrogen absorption rate and parameters such as stress; establish the relationship between hydrogen chemical potential and stress based on the steady-state hydrogen concentration distribution; construct a finite element model with the hydrogen-filled distribution as the initial state, use the flux equation, iteratively adjust the stress-related diffusion coefficient D, match the simulated short-term diffusion distribution with the actual test data, and determine the variation law of D with stress.

[0013] In some embodiments, in step 1, the sample is processed into a U-shaped or C-shaped specimen.

[0014] In some embodiments, in step 1, the average diffusion distance is approximately 1 / 4 of the sample thickness d for short-term diffusion and twice the sample extension length L for long-term diffusion.

[0015] In some embodiments, step 1 specifically includes:

[0016] Step 1.1: Remove hydrogen from the raw material using a vacuum thermal extraction method, process it into a self-loading U-shaped or C-shaped sample, compress the sample under a universal testing machine, record the pressure when compressed to a specific position, unload and then load it with bolts to compress it to the same position.

[0017] Step 1.2: Use a gas phase hydrogen charging device to charge the loaded sample with hydrogen. Before charging, calculate the maximum amount of hydrogen that can be charged and the corresponding maximum charging pressure based on the solubility of hydrogen in the material. The average hydrogen concentration should be no less than 5 ppm. The surface oxide film of the hydrogen-charged sample should be completely removed and the sample should be loaded under inert gas protection.

[0018] Step 1.3: Short-term heat preservation diffusion. Heat preservation diffusion is carried out directly in the air environment. The average diffusion distance of short-term heat preservation diffusion is 1 / 4 of the sample thickness d.

[0019] Step 1.4: Long-term heat preservation diffusion, the average diffusion distance is twice the sample extension length L.

[0020] In some embodiments, in step 2, a hydrogen concentration distribution test is performed after gas-phase hydrogen charging to obtain the hydrogen content distribution of the sample after gas-phase hydrogen charging, and the hydrogen absorption rate is calculated accordingly.

[0021] In some embodiments, in step 2, a hydrogen concentration distribution test is performed after short-term heat preservation to obtain the hydrogen content distribution of the sample after short-term heat preservation and diffusion.

[0022] In some embodiments, in step 2, a hydrogen concentration distribution test is performed after long-term heat preservation to obtain the hydrogen content distribution of the sample after long-term heat preservation and diffusion in order to calculate the hydrogen chemical potential.

[0023] In some embodiments, in step 3, the hydrogen absorption rate at different stresses is calculated based on the pressure drop curve during the hydrogen charging process, the hydrogen concentration distribution after gas-phase hydrogen charging, and the initial hydrogen concentration distribution, and the relationship between the hydrogen absorption rate and parameters such as stress is fitted.

[0024] In some embodiments, in step 3, after prolonged heat preservation, the hydrogen concentration distribution reaches a steady state. The hydrogen chemical potential gradient is the sum of the hydrogen concentration gradient and the chemical potential gradient caused by stress. When the steady state is reached, the chemical potential gradient caused by stress is equal in magnitude and opposite in direction to the concentration gradient, as shown in the formula:

[0025]

[0026] In the formula, M is the proportionality coefficient and D is the diffusion coefficient. The hydrogen chemical potential gradient caused by stress. For the concentration gradient.

[0027] In some embodiments, in step 3, diffusion parameters are calculated. When the hydrogen concentration is low, it is assumed that the diffusion coefficient does not change with the hydrogen concentration. A finite element diffusion model is established, and the hydrogen concentration distribution after hydrogen filling in the gas phase is taken as the initial state of diffusion. The diffusion flux equation is:

[0028]

[0029] When using u = -c to obtain the variation law of u with stress, let M = D, first assume a function of D as a function of stress, substitute the short-term heat preservation time, calculate the hydrogen concentration distribution after diffusion, and compare it with the actual hydrogen concentration distribution after short-term heat preservation. Then, gradually adjust the function of D as a function of stress until the two match, and finally obtain the function of D as a function of stress.

[0030] Compared with existing technologies, the method for testing hydrogen absorption and diffusion parameters of metals under stress fields provided in this application has the following advantages:

[0031] 1. This application uses a gas-phase hydrogen charging and thermal diffusion method, which has a wider applicable temperature range, exceeding 95°C;

[0032] 2. A single test can reveal the influence patterns of various stress states, from compressive stress to tensile stress;

[0033] 3. This application can obtain a quantitative law on the influence of stress on the hydrogen absorption rate in the gas phase of the material;

[0034] 4. This application can obtain the quantitative influence law of stress on the chemical potential of hydrogen in materials. Attached Figure Description

[0035] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the technical description will be briefly introduced below.

[0036] Figure 1 A flowchart of the method for testing hydrogen absorption and hydrogen diffusion parameters of metals under stress field provided in this application;

[0037] Figure 2 A schematic diagram of the test and calculation process for hydrogen absorption and hydrogen diffusion parameters of metals under stress field provided in this application;

[0038] Figure 3 A front view of the C-type specimen provided in this application;

[0039] Figure 4 A side view of the C-type specimen provided in this application. Detailed Implementation

[0040] The following detailed description provides further details on specific implementation methods.

[0041] like Figure 1 and Figure 2 As shown. This application provides a method for testing hydrogen absorption and hydrogen diffusion parameters of a metal under a stress field, including:

[0042] Step 1: Sample preparation. After dehydrogenation by vacuum thermal extraction, the sample is processed into U-shaped or C-shaped specimens. It is then loaded under compression and inert gas protection, followed by gas-phase hydrogen charging and control of hydrogen concentration. Subsequently, short-term and long-term heat preservation diffusion are carried out in stages to optimize hydrogen distribution.

[0043] Step 2: Sample Testing. The sample is tested using neutron scattering (with a control sample) or multi-point sampling. The hydrogen distribution is measured sequentially before hydrogen charging, after hydrogen charging, and after short-term and long-term heat preservation. These measurements are used for background subtraction, hydrogen absorption rate calculation, diffusion coefficient determination, and chemical potential analysis.

[0044] Step 3: Parameter Calculation. Calculate the stress distribution, hydrogen absorption parameters, hydrogen chemical potential, and diffusion parameters. Analyze the stress distribution of the self-loaded sample using the finite element method. Combine the hydrogen charging pressure drop curve with the concentration distribution difference to calculate the hydrogen absorption rate in each stress zone, and establish a mathematical model of its relationship with stress and hydrogen pressure. Based on the steady-state hydrogen concentration distribution, establish the relationship between hydrogen chemical potential and stress. By constructing a finite element model with the hydrogen distribution after charging as the initial state, use the diffusion equation to iteratively adjust the stress-related diffusion coefficient D (such as a polynomial function) to match the simulated short-term diffusion distribution with the actual test data, and finally determine the variation of D with stress.

[0045] Step 1 specifically includes:

[0046] Step 1.1: Sample preparation, including three steps: raw material processing, sample preparation, and loading. The raw material should contain as little hydrogen as possible. If the raw material has a high hydrogen content, it can be removed using vacuum thermal extraction, i.e., the material is placed in a high-vacuum chamber (typically at a pressure below 4 × 10⁻⁶). -6 (Pa), then heat it to a higher temperature that does not cause tissue changes, releasing the hydrogen. Afterwards, referring to GB / T15970.3 and GB / T15970.5, process it into a self-loading U-shaped or C-shaped specimen, such as... Figure 3 and Figure 4 As shown in the figure, L represents the length direction, w represents the width direction, d represents the thickness direction, A represents the position of maximum tensile stress, B represents the position of maximum compressive stress, and C represents the position of near-stress-free stress. The specimen was compressed under a universal testing machine, and the pressure at a specific compression point was recorded. After unloading, a bolt was used to reload the specimen, compressing it to the same position. At this point, the stress on the specimen was consistent with the previous compressor pressure. To avoid the influence of the bolt on hydrogen diffusion in the specimen, a ceramic gasket was used to separate the bolt and the specimen.

[0047] Step 1.2: Gas-phase hydrogen charging. The loaded sample is charged with hydrogen using a gas-phase hydrogen charging device. Before charging, the maximum chargeable hydrogen amount and corresponding maximum charging pressure should be calculated based on the solubility of hydrogen in the material at the test temperature. The actual charging pressure should be lower than the maximum charging pressure. Simultaneously, considering the accuracy of subsequent tests, the average hydrogen concentration used in this embodiment is not less than 5 ppm (mass fraction). The charging temperature can be flexibly selected based on the actual service temperature of the material or the accelerated testing temperature, but should not exceed the stress relief temperature of the material. Under inert gas protection, the inner and outer surfaces of the sample are gently polished with fine sandpaper to remove the oxide film (the oxide film on the side of the sample is retained to avoid side hydrogen absorption), and then the sample is loaded to minimize the obstruction of hydrogen absorption by the oxide film on the inner and outer surfaces and improve the hydrogen absorption rate. The charging time should be short, and the average diffusion distance should preferably not exceed 1 / 20 of the sample thickness d to reduce internal diffusion.

[0048] Step 1.3: Short-duration heat preservation diffusion. Zirconium-like alloys have extremely low hydrogen equilibrium partial pressures at relatively low temperatures (below the stress-relief temperature), so there's no need to consider hydrogen release into the air. Furthermore, heating in air quickly forms an oxide film on the surface, and the oxide film also eliminates the need to consider hydrogen absorption from the air. Therefore, heat preservation diffusion can be carried out directly in an air environment. For short-duration heat preservation diffusion, the average diffusion distance d1 should ideally be approximately 1 / 4 of the sample thickness d. The diffusion time is calculated using the following formula:

[0049]

[0050] In the formula, t is the heat preservation diffusion time, d1 is the average diffusion distance, and D is the diffusion coefficient (the diffusion coefficient under no stress can be used here).

[0051] Step 1.4: Long-term heat preservation diffusion. For long-term heat preservation diffusion, the average diffusion distance should ideally be approximately twice the specimen's extension length L. The calculation method for the heat preservation diffusion time is the same as above. Based on this and the acceptable heat preservation time, the size of the U-shaped specimen can be designed in reverse.

[0052] In step 2, the hydrogen distribution test is performed using neutron scattering along the direction perpendicular to the U-shaped surface (i.e., along the width w). (Since the sample has an oxide film on its sides, it can be assumed that the sides do not absorb hydrogen, only the inner and outer surfaces absorb hydrogen. Therefore, it can be reasonably assumed that the hydrogen distribution in the w direction is uniform, and the subsequent hydrogen absorption diffusion model can be simplified to a two-dimensional model). During the neutron scattering test, samples of the same material and width but different hydrogen concentrations (prepared using gas phase absorption) can be placed simultaneously as calibration samples to improve test accuracy. When neutron scattering test conditions are unavailable, a multi-point sampling test method is used (specific test methods include vacuum thermal extraction-mass spectrometry, inert gas melting-thermal conductivity, etc.). Since the latter is a destructive test method, multiple samples need to be prepared, and at least one sample must be taken for testing in each step.

[0053] In step 2, an initial hydrogen distribution test is performed. The hydrogen content distribution of the sample gas phase before hydrogen charging is obtained and used as a background, which needs to be considered in subsequent calculations.

[0054] In step 2, the hydrogen concentration distribution after gas-phase hydrogen charging is tested. The difference between the hydrogen content distribution after gas-phase hydrogen charging and the initial hydrogen content distribution is the absorbed hydrogen content, and the hydrogen absorption rate is calculated accordingly.

[0055] In step 2, the hydrogen concentration distribution after short-term heat preservation is tested. The hydrogen content distribution after short-term heat preservation and diffusion is obtained and used for diffusion coefficient calculation.

[0056] In step 2, the hydrogen concentration distribution after long-term heat preservation is tested. The hydrogen content distribution after long-term heat preservation and diffusion is obtained and used for hydrogen chemical potential calculation.

[0057] In step 3, stress distribution calculation is performed. The stress distribution in the self-loaded sample is calculated using the finite element method.

[0058] In step 3, hydrogen absorption parameters are calculated. Based on the pressure drop curve during the hydrogen charging process, the hydrogen concentration distribution after gas-phase hydrogen charging, and the initial hydrogen concentration distribution, the hydrogen absorption rate at different stress points is calculated (when the total amount of hydrogen absorbed is small, it can be reasonably assumed that the ratio of the hydrogen absorption rate at different locations remains constant throughout the hydrogen absorption process), and the relationship between the hydrogen absorption rate and parameters such as stress and upstream pressure is fitted.

[0059] In step 3, the hydrogen chemical potential is calculated. After prolonged heat preservation, the hydrogen concentration distribution reaches a steady state, meaning the hydrogen chemical potential at different locations reaches equilibrium. The hydrogen chemical potential gradient is the sum of the hydrogen concentration gradient and the chemical potential gradient caused by stress. In other words, when the steady state is finally reached, the chemical potential gradient caused by stress at different locations is equal in magnitude and opposite in direction to the concentration gradient. The formula is:

[0060]

[0061] In the formula, M is the proportionality coefficient, i.e., the generalized diffusion coefficient, and D is the diffusion coefficient. The hydrogen chemical potential gradient caused by stress. For the concentration gradient.

[0062] Therefore, the relationship between stress and hydrogen chemical potential caused by stress can be calculated based on stress and hydrogen concentration at different locations. If only the effects of these two factors on diffusion are considered, without regard to dimensional differences, and only considering numerical values, and setting M = D, it can be simplified to the following formula:

[0063] u＝ -c(Equation 2)

[0064] In the formula, u is the hydrogen chemical potential caused by stress, and c is the hydrogen concentration.

[0065] In step 3, diffusion parameters are calculated. When the hydrogen concentration is low, it can be reasonably assumed that the diffusion coefficient does not change with the hydrogen concentration. First, a finite element diffusion model is established, with the hydrogen concentration distribution after hydrogen filling in the gas phase as the initial state of diffusion. The diffusion flux equation is:

[0066]

[0067] When using Equation 2 to obtain the variation law of u with stress, we can let M = D, first assume a function of D value with stress (the greater the tensile stress, the faster the diffusion, for example, a polynomial function can be taken), substitute the short-term heat preservation time, calculate the hydrogen concentration distribution after diffusion, and compare it with the actual hydrogen concentration distribution after short-term heat preservation. Then, we gradually adjust the function of D value with stress until the two match well, and finally obtain the function of D value with stress.

[0068] Therefore, the method for testing hydrogen absorption and diffusion parameters of metals under stress field provided in this application mainly includes sample preparation, gas-phase hydrogen filling, thermal diffusion, hydrogen distribution testing, and calculation.

[0069] (1) Sample preparation. Use self-loading specimens such as U-shaped or C-shaped specimens. For specific preparation methods, please refer to GB / T15970.3 and GB / T15970.5.

[0070] (2) Gas-phase hydrogen charging. A gas-phase hydrogen charging device is used to charge the loaded sample with hydrogen. The charging time should be short to reduce internal diffusion. The charging temperature can be flexibly selected based on the material's actual service temperature or accelerated testing temperature, but should not exceed the material's stress relief temperature.

[0071] (3) Thermal diffusion. The hydrogen-filled sample is subjected to thermal diffusion to allow the hydrogen to redistribute freely. The thermal diffusion temperature can be flexibly selected according to the actual service temperature of the material or the accelerated test temperature, but it shall not exceed the stress relief temperature of the material. There are several options for the thermal diffusion time: when the time is long enough (i.e., hydrogen diffuses to a steady state), the hydrogen distribution is related to the chemical potential; when the thermal diffusion time is relatively short, the hydrogen distribution is related to the hydrogen diffusion process.

[0072] (4) Hydrogen distribution test. When there is a standard sample of the same material and thickness, the neutron scattering method is preferred; other methods include multiple local sampling tests, and then fitting the hydrogen concentration distribution based on the concentration at multiple points.

[0073] (5) Calculations. These mainly include stress distribution calculation, hydrogen absorption parameter calculation, hydrogen chemical potential calculation, and hydrogen diffusion calculation. The stress distribution is calculated using the finite element method based on the sample's mechanical properties, dimensions, loading parameters, and test temperature. The hydrogen absorption parameter is calculated as a function of stress variation. First, the ratio of hydrogen absorption rates at different locations is obtained from the hydrogen distribution after hydrogen filling (assuming this ratio remains constant during hydrogen filling). Then, it is calculated based on the pressure-time curve during hydrogen filling. The hydrogen chemical potential as a function of stress variation can be calculated based on the hydrogen distribution in a sample with a sufficiently long holding time (hydrogen concentration is proportional to the absolute value of the hydrogen chemical potential). The hydrogen diffusion coefficient as a function of stress variation is calculated as follows: based on the hydrogen distribution after gas-phase hydrogen filling (i.e., the initial state of diffusion), the hydrogen diffusion coefficient as a function of stress variation (first assumed, then gradually optimized), the hydrogen chemical potential as a function of stress variation, the holding temperature, and the diffusion time, the hydrogen distribution at the end of the holding period is calculated and compared with the hydrogen distribution test results. The hydrogen diffusion coefficient as a function of stress variation is gradually optimized until the calculated hydrogen distribution matches the test results.

[0074] Through the above tests and calculations, we can obtain the hydrogen absorption parameters, hydrogen chemical potential, and diffusion coefficient of zirconium-like alloys as a function of stress.

[0075] The above description is only a specific embodiment of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application.

Claims

1. A method for testing hydrogen absorption and diffusion parameters of a metal under a stress field, characterized in that, include: Step 1: After vacuum thermal extraction to remove hydrogen, the sample is processed into a specimen, compressed and loaded, subjected to gas-phase hydrogen charging with controlled hydrogen concentration, and subjected to short-term and long-term heat preservation diffusion in stages; Step 1 includes: Step 1.1: Remove hydrogen from the raw material using a vacuum thermal extraction method and process it into a self-loading U-shaped or C-shaped sample; the specific steps of processing it into a self-loading U-shaped or C-shaped sample include: compressing the sample under a universal testing machine to form a U-shaped or C-shaped sample, recording the pressure when compressed to a specific position, unloading and then loading it with bolts to compress it to the same position, thereby obtaining a self-loading U-shaped or C-shaped sample; Step 1.2: Use a gas-phase hydrogen charging device to charge the self-loaded U-shaped or C-shaped sample with hydrogen; Step 2: Test the self-loaded U-shaped or C-shaped sample, and measure the hydrogen concentration distribution before hydrogen filling, after hydrogen filling, and after short-term and long-term heat preservation and diffusion in sequence. Step 3: Analyze the stress distribution of the self-loaded sample using the finite element method, calculate the hydrogen absorption rate at different stresses, and fit the relationship between the hydrogen absorption rate and parameters, including stress; based on the steady-state hydrogen concentration distribution, establish the relationship between the hydrogen chemical potential caused by stress and stress; by constructing a finite element model, taking the hydrogen concentration distribution after hydrogen filling as the initial state, and using the diffusion flux equation, iteratively adjust the stress-related diffusion coefficient D to match the simulated hydrogen concentration distribution after short-term heat preservation diffusion with the actual tested hydrogen concentration distribution after short-term heat preservation diffusion, and determine the variation law of the stress-related diffusion coefficient D with stress; The total hydrogen chemical potential gradient is the sum of the hydrogen concentration gradient and the stress-induced chemical potential gradient. After long-term heat preservation and diffusion, the hydrogen concentration distribution reaches a steady state. At the steady state, the stress-induced hydrogen chemical potential gradient is equal in magnitude and opposite in direction to the hydrogen concentration gradient, as shown in the formula: In the formula, M is the proportionality coefficient, and D is the diffusion coefficient. The hydrogen chemical potential gradient caused by stress. For hydrogen concentration gradient; To calculate the diffusion coefficient, when the hydrogen concentration is low, it is assumed that the diffusion coefficient does not change with the hydrogen concentration. A finite element diffusion model is established, with the hydrogen concentration distribution after hydrogen filling in the gas phase as the initial state of diffusion. The diffusion flux equation is: When using u =- c When obtaining the variation law of u with stress, let M=D, first assume a function of D value with stress, substitute the short-time heat preservation diffusion time, calculate the hydrogen concentration distribution after short-time heat preservation diffusion, and compare it with the actual hydrogen concentration distribution after short-time heat preservation diffusion. Then, gradually adjust the function of D value with stress until the two match, and finally obtain the function of D value with stress.

2. The method for testing hydrogen absorption and hydrogen diffusion parameters of metals under stress field according to claim 1, characterized in that, In step 1, the average diffusion distance for short-term heat preservation diffusion is 1 / 4 of the sample thickness d, and the average diffusion distance for long-term heat preservation diffusion is twice the sample extension length L.

3. The method for testing hydrogen absorption and hydrogen diffusion parameters of metals under stress field according to claim 1, characterized in that, Step 1 also includes: Step 1.2: Use a gas phase hydrogen charging device to charge the self-loaded U-shaped or C-shaped sample with hydrogen. Before charging, calculate the maximum amount of hydrogen that can be charged and the corresponding maximum charging pressure based on the solubility of hydrogen in the material. The average hydrogen concentration should be not less than 5 ppm. The surface oxide film of the hydrogen-charged sample should be completely removed and the sample should be loaded under inert gas protection. Step 1.3: Short-term heat preservation diffusion. Heat preservation diffusion is carried out directly in the air environment. The average diffusion distance of short-term heat preservation diffusion is 1 / 4 of the sample thickness d. Step 1.4: Long-term heat preservation diffusion. The average diffusion distance of long-term heat preservation diffusion is twice the sample extension length L.

4. The method for testing hydrogen absorption and hydrogen diffusion parameters of metals under stress field according to claim 1, characterized in that, In step 2, the hydrogen concentration distribution after gas-phase hydrogen charging is tested to obtain the hydrogen content distribution of the sample after gas-phase hydrogen charging, and the hydrogen absorption rate is calculated accordingly.

5. The method for testing hydrogen absorption and hydrogen diffusion parameters of metals under stress field according to claim 1, characterized in that, In step 2, the hydrogen concentration distribution after short-term heat preservation and diffusion is tested to obtain the hydrogen content distribution of the sample after short-term heat preservation and diffusion.

6. The method for testing hydrogen absorption and hydrogen diffusion parameters of metals under stress field according to claim 1, characterized in that, In step 2, the hydrogen concentration distribution after long-term heat preservation and diffusion is tested to obtain the hydrogen content distribution of the sample after long-term heat preservation and diffusion in order to calculate the hydrogen chemical potential.

7. The method for testing hydrogen absorption and hydrogen diffusion parameters of metals under stress field according to claim 1, characterized in that, In step 3, based on the pressure drop curve during the hydrogen charging process, the hydrogen concentration distribution after gas-phase hydrogen charging, and the initial hydrogen concentration distribution, the hydrogen absorption rate at different stress points is calculated, and the relationship between the hydrogen absorption rate and the parameters is fitted.

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